CA1221054A - Electro-osmotic production of hydrocarbons utilizing conduction heating of hydrocarbonaceous formations - Google Patents
Electro-osmotic production of hydrocarbons utilizing conduction heating of hydrocarbonaceous formationsInfo
- Publication number
- CA1221054A CA1221054A CA000452976A CA452976A CA1221054A CA 1221054 A CA1221054 A CA 1221054A CA 000452976 A CA000452976 A CA 000452976A CA 452976 A CA452976 A CA 452976A CA 1221054 A CA1221054 A CA 1221054A
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- CA
- Canada
- Prior art keywords
- electrodes
- formation
- row
- fluids
- electro
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000005755 formation reaction Methods 0.000 title claims abstract description 68
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 67
- 238000010438 heat treatment Methods 0.000 title claims abstract description 44
- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 16
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 16
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 11
- 238000000034 method Methods 0.000 claims abstract description 40
- 239000012530 fluid Substances 0.000 claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000000926 separation method Methods 0.000 claims abstract description 11
- 238000011065 in-situ storage Methods 0.000 claims abstract description 4
- 238000009835 boiling Methods 0.000 claims abstract 2
- 239000011244 liquid electrolyte Substances 0.000 claims abstract 2
- 239000003792 electrolyte Substances 0.000 claims description 16
- 238000005370 electroosmosis Methods 0.000 claims description 11
- 229920000642 polymer Polymers 0.000 claims description 6
- 239000004094 surface-active agent Substances 0.000 claims description 6
- 230000005484 gravity Effects 0.000 claims description 5
- 230000005684 electric field Effects 0.000 claims description 4
- 238000011084 recovery Methods 0.000 claims description 4
- 238000009834 vaporization Methods 0.000 abstract description 9
- 230000008016 vaporization Effects 0.000 abstract description 9
- 239000004020 conductor Substances 0.000 description 7
- 238000003491 array Methods 0.000 description 6
- 230000003247 decreasing effect Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000000295 fuel oil Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
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- 238000012545 processing Methods 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 241000331231 Amorphocerini gen. n. 1 DAD-2008 Species 0.000 description 1
- 244000240551 Brassica parachinensis Species 0.000 description 1
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 241000000239 Colwellia polaris Species 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000489861 Maximus Species 0.000 description 1
- 241000184339 Nemophila maculata Species 0.000 description 1
- 241001080526 Vertica Species 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/2401—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection by means of electricity
Abstract
ABSTRACT OF THE DISCLOSURE
An electro-osmotic method for the production of hydrocarbons utilizes in situ heating of earth formations having substantial electrical conductivity.
A particular volume of an earth formation is bounded with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array wherein the active electrode area and the row separation are chosen in reference to the deposit thickness to avoid heating barren layers. Electrical power is applied at no more than a relatively low frequency between respective rows of electrodes to deliver power to the formation while producing relatively uniform heating thereof and limiting the relative loss of heat to adjacent regions to less than a predetermined amount.
At the same time the temperature of the electrodes is controlled near the vaporization point of water to maintain an electrically conductive path between the electrodes and the formation. A heat sink is provided by supplying aqueous liquid electrolyte to space between the electrodes and the adjacent formation, thereby maintaining the temperature thereat no greater than about the boiling point of water and maintaining a conductive path between said formation. A d.c.
polarized potential is applied to enhance flow of reservoir fluid into a preselected row of electrodes, and collected reservoir fluids are removed from the electrodes in the preselected row.
An electro-osmotic method for the production of hydrocarbons utilizes in situ heating of earth formations having substantial electrical conductivity.
A particular volume of an earth formation is bounded with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array wherein the active electrode area and the row separation are chosen in reference to the deposit thickness to avoid heating barren layers. Electrical power is applied at no more than a relatively low frequency between respective rows of electrodes to deliver power to the formation while producing relatively uniform heating thereof and limiting the relative loss of heat to adjacent regions to less than a predetermined amount.
At the same time the temperature of the electrodes is controlled near the vaporization point of water to maintain an electrically conductive path between the electrodes and the formation. A heat sink is provided by supplying aqueous liquid electrolyte to space between the electrodes and the adjacent formation, thereby maintaining the temperature thereat no greater than about the boiling point of water and maintaining a conductive path between said formation. A d.c.
polarized potential is applied to enhance flow of reservoir fluid into a preselected row of electrodes, and collected reservoir fluids are removed from the electrodes in the preselected row.
Description
~:Z1~59L
EL~C'rRO-OSMOTIC PF~ODUCTION OF HYDP~OCARP,~NS U~ILIZI~G
CONDUCI'IOL~ HEATING OF ~YDROC~RBONACEOU5 FORMATIONS
BACKGROU~D OF THE I~VENTIO~
~This invention relates generally to the exploitation of hydrocarl~on-bearing formations having substantial electrieal conductivity, such as t~r sands and heavy oil deposits, by the applica-tion of eLectrical eneryy to heat the deposits. More specifically, the invention relates to the delivery of electrical power to a eonductive -formation at relatively low frequenc~ or d.c., whicll po~er is appliecl between rows of elongatec~
electrodes forming a waveguide structure bol1nding a particular volume of the formation, while at the same time the temperature of the eleetrodes is controlled.
Materials such as tar sands and heavy oil deposits are amenable to heat processing to produce gases and hydrocarbons. Generally the heat develops the porosity, permeability ancl/or mobility neeessary for reeovery. Some hydrocarbonaceous materials may be reeovered upon pyrolysis or distillation, others simply upon heating to inerease mobility.
Materials such as tar sands and heavy oil deposits are heterogeneous dieleetries. Sueh dielectric media exhibit very large values of conduetivity, relative dieleetrie eonstant, and loss tangents at low temperature, but at high temperatures exhibit lower values for these parameters. Such behavior arises beeause in sueh media, ionie eonducting paths or layers are established in the moisture contained in the interstitial spaces in the porous, relatively lo~
dieleetric eonstant and loss tangent rock matrix. IJpon heating, the moisture evaporates, l~hich radically reduces the bulk conductivity, relative clielectrie eonstant, and loss tangent to essentially that of the roek matrix.
It has been known to heat eleetrieally relatively large volumes of hydroearbonaeeous formations .,h ~221~5~
in si-tu. Briclges ancl Taflove Vnited States Reissue Patent No. Re. 30,73~ cliscloses a system and method for such ln _tu heat processing of llydrocarbonaceous earth formations wherein a plurality of elongated electrodes are inserted in formations and bound a particu]ar volume of a formation of interest. As used therein, the term "bounding a particular formation" means that the volume is enclosed on at least two sides thereof. The enclosed sides are enclosecl in an electrical sense with a ro-~l of cliscrete electrodes forming a par-ticular side.
Electrical excitation between rows of S-lCh electrodes established electrical fie]ds ;n the volume. As disclosed in such patent, the frequency of the excitation was selected as a function of the bollnded volume so as to establish a substantially nonradiating electric field which was confined substantially in the volume. The method and system of the reissue patent have particular application in the radio-frequency heating of moderately lossy dielectric formations at relatively high frequency. However, it is also useful in relatively lossy dielectric formations where relatively low frequency electrical power is utilizecl for heating largely by conduction. The present invention is directecd toward the improvement of such method and system for such heating of relatively conductive formations at relatively low frequency an~ to the application of such system for heating with d.c.
SUM~ARY OF THE IN~ENTION
An electro-osmotic method for the production ~f hydrocarbons utilizes in situ heating of earth for~ations having substantial electrical conductivity occasioned by the presence of water. A particular volume of an earth formation is bouncled with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array with the spacing between rows greater than the distance between electrodes in a row wherein the active electrode area ~2~1~5~
and tne row separation are chosen in reference to the formation thickness to avoid heating barren layers, the row separation being no greater than about the thickness of the formation. Electrical power is applied at no more than a relatlvely low frequency between respectlve rows of electrodes to dellver power to the houndecl volume of the formatlon wlllle produclng relatively uniform heating -thereof and llmltlng the re]ative loss of heat to adjacent reglons. A d.c. polari~ed potentlal is utilized to make the electrodes of one row anodlc and the electrodes of another row cathodic ancl thereby enhance the flow of reservoir fluid toward at least one preselecte-1 electrode. At the same time the temperature of the electrocles ls controlled to retain water and thereby maintain an electrically condllctive path between the electrodes and the formation. Reservolr flulds that have flowed between the rows toward the at least one preselected electrode are removed.
In one aspect of the invention a remote qround is used for cathodic contact.
These and other aspects and advantages of the present invention will become more apparent -from the following detailed description, partlcularly when taken in conjunction with the accompanying drawings.
~RIEF DESCRIPTIO~ OF THE DRAWINGS
FIGURE 1 is a vertical sectional view, partly diagrammatic, of a preferred em~odiment of a system for the conductive heating of an earth formation in accordance with t~e present invention, wherein an array of electrodes is emplaced vertically, the section belnq taken transversely of the rows of elec-trodes;
FIGURE 2 is a diagrammatlc plan view of the system shown in FIGURE l;
FIGURE 3 is an enlarged vertical sectional view, partly diagrammatic, of part of the system shown in FIGUR~ l;
~2210S~
. 4 FIGURE 4 is a vertica:L sectional view, partly diayramma~ic, of an alternative system for the conductive heating of an earth forTnati.on in accorclance with the presen-t invention, wherein an array of electrodes is emplaced hori~ontally, the section being taken longitudinally of the electrodes;
FIGURE 5 is a vertical sectional view, partly diagrammatic of the system shown in FIGURR ~, talcen along line 5-5 of FIGURr. 4;
FIGURE 6 is a vertical sectional view comparable to that of FIGURE ~ showing an alternative system with hori~ontal electrodes fed fxom both ends;
FIGUP~E 7 is a plan view, mostly diaqrammatic, of an alternative syste~ comparahle to that shown in FIGUXE 3, with cool walls adjacent electrodes;
FIGURE 8 is a vertical sectional view, part].y diagrammatic of the system shown in FIGURE 7, taken along line 8-8 of FIGURE 7;
E'IGURE 9 is a set of curves showing the relationship between a time dependent factor c and heat loss and a function of deposit temperature utilizing the present invention;
FIGURE 10 is a set of curves showing the temperature distribution at different heating rates when heat is delivered to a defined volume;
FIGURE 11 is a set of curves showing the relationship between time and temperature at different points when a formation is heated by a sparse array;
FIGURE 12 is a set of curves showin~ the relationship between time and temperature at ~ifferent points when a formation is heated in accordance with the present invention with electrode diameters of 32 inches;
and FIGURE 13 is a set of curves showing the relationship of time and temperature at the same points as in FIG~RE 12 in accordance with the present invention with electrode diameters of 1~ inches.
~2~S~
DETAIJ~ DESCRIPTIOi~, OF T~-IE PREFERRED EI~ODIMFNTS
, FIGURES 1, 2 and 3 i]lustrate a syste~ for heating conductive formations utilizing an array 10 of vertical electrodes 12, 14, the electrocles 12 beinq 5 grounded, ancl the electrodes 14 being enerqized by a low frec~uency or d.c. scurce 16 of electrical power by means of a coaxial line 17. r~le electrodes 12, 14 are disposed in respective parallel rows spacecl a spacing s apart with the electrodes spacecl apart a distance d in the respective rows. The electrode array 10 is A dense array, meaning tllat the spacing 5 between rows is greater than the distance _ between e]ectrodes in a row. The rows of electrocles 12 are longer than the rows of electrodes 14 to con~ine t~e electric fiel~s an~
consequent heating at the ends of the rows of electrodes 14.
The electrodes 12, 14 are tubular electrodes emplaced in respective boreholes 18. The electrodes may be emplacecl from a minecl drift 20 accessed through a shaft 22 from the surface 24 of the earth. rFhe electrodes 12 preferably extencl, as .shown, t11rougl~ a deposit 26 or earth formation containing the hydrocarbons to be produced. The electrodes 12 extend into the overburden 28 above the deposit 26 and into the 25 underburden 30 below the deposit 26. The electrodes 14, on the other hand, are shorter than the electrodes 12 and extend only part way through the deposit 26, short of the overburden 28 and underburden 30. In order to avoid heating the underburden and to provide the power connection, the lower portions of the electrodes 1~ may be insulated from the formations by insulators 31, which may be air. The effective lengths o-f the electrodes 14 therefore end at the insulators 31.
FIGURES 4 and 5 illustrate a system for heatinq conductive formations utilizing an array 32 o~
horizontal electrodes 34, 36 disposed in vertically spaced parallel rows, the electrodes 34 being in the ,~
lZ21~54 upper row and the elec-trodes 36 in the lower row. The upper electrodes 34 are preferably groundecl, and the lower electrodes 36 are energized by a low frequency or d.c. source 38 of e]ectrical power. I'he electrodes 34, 36 are disposed in parallel rows spaced apart a spacing s, t~ith the electrodes spaced apart a clistance d in the respective rows. rne electrode array 32 ls also a dense array. The upper row of electrodes 34 is longer than the lower row of electrodes 3~ to confine the electric fields from the electrodes 36. The electrodes 3~ extend beyond both ends of the electrodes 3G for the same reason. Grounding the upper electrodes 34 ]ceeps down stray fielc~s at t11e sur~ace 24 of the earth.
The electrodes 34, 36 are tubular e]ectrodes emplaced in respective boreholes 40 which may be drilled by well ]cnown directional drilling techniques to provide horizontal boreholes at the top and bottom of tlle deposit 2G between the overburden 28 and the underburden 30. Preferably the upper boreholes are at the interface between the deposit 26 and the overburden 28, and tlle lower boreholes are slightly above the interface between the deposit 26 and tihe underburden 30.
FIGURE 6 illustrates a system comparable to that shown in FIGURES 4 and 5 wherein the array is fed from both ends, a second power source 42 being connected at the end remote from the power source 38.
FIGURES 7 and 8 illustrate a system comparable to that of FIGURES 1, 2 and 3 with an array of vertical electrodes. In this system the rows of like electrodes 12, 14 are in spaced pairs to provide a low field region 44 therebetween that is not directly lleated to any qreat extent.
I'he deposit thickness h and the average or effective thermal diffusion properties determine the uniformity of the temperature distribution as a function of heating time t and can be generally described for any ~Z~1~54 thickness oE a deposit in the -terms of a deposit temperature profile factor c, such that c = kt/(h/2) where _ is the thermal diffusivity. FIGURE 9 ~resents a curve ~ showing the relationsh-ip between the factor c and the portion of a deposit above ~0% of the temperature rise oE the center of the deposit for a uniform heating rate through the heated volume. Note that at c = 0.1, about 75% of the heate~ volume 11~S a temperature rise ~Leater tllan ~30% of the temperature rise of the center of the heated volume.
FIGVRE 10 illustrates the heatinq profiles for three values of the factor c as a function of the distance from the center of the heated volume, the fraction of the temperature rise that would have been reached in -the heated ~7Olume in the absence of heat outflow. Note that where c = 0.1 or c - 0.2, the tota]
percentage of heat lost to adjacent formatlons is relatively small, about 10% to 15%. I~here low flnal temperatures, e.g., less than lO0DC, are suitable, c up to 0.3 can be accepted, as the heat lost, or extra heat needed to maintain the final temperature, is, while significant, economically acceptable. FIGURE 9, curve B, showing percent heat loss as a function of the factor c, shows percent heat loss to be less than 25~ at c =
0.3. On the other hand, if higher temperatures (e.q., about 200C) are desired to crack the bitumen, then higher central deposit temperatures above the design minimum are needed to process more of the deposit, especially if longer heating times are employe~l.
Moreover, the heat outflows at these higher temperatures are more economically disadvantageous. Thus a temperature profile factor of c 1ess than about 0.15 is required. In general the heating rate should be great enough that c is less than 30 times the inverse of the ultimate increase in temperature ~T in degrees ce]sius of the volume:
c < 0.3(100/~T) , ~' :~221~54 The lowest values of c are controllecl more l~y the excess temperature oE electxodes and are discllssed 'nelow.
The electrode spacing distance d and diameter a are determined by the maximum allowal~le electrocle temperature plus some excess if some local vaporization of the electrolyte ancl connate water can be tolerate-l.
In a reasonably dense array, t'ne hot regions aroun~ t'ne electrodes are confined to the immediate vicinity of the electrodes. On the other hand, in a sparse array, where s is no greater than d, the excess heat zone comprises a major portion of the deposi-t.
FIGURE ll i llustrates a gross]y excessive heat bulld-up on the electrodes as compared to the center of ~l~e deposit for a sparse array. In this exaJ~p1e ro~Y
spacing s was lOm, electrode spacing cl ]Om, electrode dlameter a 0.8m, and thermal diffusivity 10 m /s, with no fluid flow.
FIGURE 12 sho~s how the electrode temperature can be reduced by the use of a dense array. In this example row spacing s was lOm, electrode spacing d 4m, electrode diameter a O.~,m, and thermal diffusivity m2/s, with no fluid flow.
FIGURE 13 illustrates the effect of decreasing the diameter of the electrodes of the dense array of FIGURE 12 such that the temperature of the electrode is increased somewhat more re]ative to the main cleposit.
In this example row spacing s was lOm, electrode spacing d 4m, electrode diameter a 0.35m, and thermal diffusivity 10 6 m /s, with no fluid flow. The region of increased temperature is confined to the immediate vicinity of the electrode and does not constitute a major energy waste. ~lIIS, varying the electrode separation distance d and the diameter of the electrode a permlt controlling the temperature of t~e electrode either to prevent vapori~.ation or excessive vaporiæation of the electrolyte in the borehole and .,, ,. ~ . i, ~z~s~
connate water in the formations immediately acljacent the electrode.
The electrode spacing _ and diameter a are cllosen so that either electrode temperature is comparable to the vaporization temperature, or if some local vapori7.ation is tolerahle (as for a moderately den~e array), the unmodified electrode temperature rise without vapor cooling will not significantly exceed the vaporization temperature~
The means for providing water for hoth vaporization and for maintenance of electrical conduction is shown in the drawings, particularly i.n FIGUl~E 3 for vertical electrodes and in FIGURÆ 4 for llorizontal electrodes. As shown ln FIGURE 3, a reservoir ~6 of aclueous electrolyte provides a conductive solution that may be pumpecl by a flow regulator and pump 47 down the shaft 22 and up the interior of the electrodes 12 and into the spaces between the electrodes 12 and the forma-tion 2G. A vapor relief pipe 48, together with a pressure regulator and pump 50 returns excess electrolyte to the reservoir 46 and assures that the electrolyte always covers the electrodes 12. Similarly, a reservoir 52 provides sucll electrolyte down the shaft 22, whence it is driven by a pressure regulator and pump 53 up the interior of the electrodes 14 and into the spaces between the electrodes 14 and the formation 26. In this case the electrodes are energi~ed and not at ground potential. The conduits 54 carrying the electrolyte through the shaft 22 are therefore at the potential of the power supply an~ mllst be insulated from ~round, as is the reservoir 52. The conduits 54 are therefore in the central conductor of the coaxial line 17. The electrodes 14 have corresponding vapor relief pipes 56 and a related pressure reyulator and pump 58.
~ s shown in FIGU~E 4, electrolyte is provided as needed from reservoirs 60, 61 to the interior tubing ~2ZlC~;4 62 which also ac~s to connect the power source 38 to t'he respective electrodes 34, 36, the tubing being insulated from the overburden 28 ancl the deposit 26 hy insulation 64. The elec-trolyte goes down the tubing 62 to kee~ the spaces between the respective electrocles ~4, 36 and the deposit 26 full of conductive solution during heating.
The tubing to t'he lower electrode 36 may later be used to pump out the oil entering the lower electrode, using a positive dis,~lacement pump G6.
In either system, the electrolyte acts as a heat sink to assure cool electrodes and maintain conductive paths between the respective electrocles and the deposit. '~'~e water in the electrolyte may hoi] an~
thereby absorb heat to cool tlle electrodes, as the water is replenished~
The vaporization temperature is controllecl hy the maximu~ sustainable pressure of the deposit.
Typically for shallow to moderate depth deposits the gauge pressure can range from a few psig to 300 psig with a maximum of about 1300 psig for practical systems. The tightness of ad~acent formations also influences the maximum sustainable vapor pressure. In some cases, injection of inert gases to assist in maintaining de~osit pressure may be needed.
Another way to keep the electrodes cool is to position the electrodes adjacent a reduced field region on one side of an active electrode row. This reduces radically the heating rate in the region of the diminished field, thus creating in effect a heat sink which radically reduces the temperature of the electrodes, in the limiting case to ahout half the temperature rise of the center portion of the deposit.
As shown in FIGUR~S 7 and 8, in the case of vertical arrays, pairs of electro-]es 12, 14 can be installed from the same drift and the same potential is applied to each pair, thus the regions 44 between the pairs become low field regions. By proper selection of pZZ10~4 heating rates and pair separation, it is possible to control the temperature of the electroc1e at slightly below that for the cen-ter of the cleposit. The thickness of the cool wall region 44 can be sufficiently thin that the cool wall region can achieve a~out 90% of the maximum deposit temperature via therma] diffusion from the heated volume after -the application of power has ended.
A~ shown in F~GUR~S 4, 5 and 6 in the case of a horizontally enlarged biplate, a near zero field region exists on the barren side of the row of grounded upper electrodes 34 and a near zero field region exists on the barren si~e of the row of energize~ electro~es 36. Suc~
low field regions act as the regions 44 in the svstem shown in FI&~RES 7 and 8.
The arrangement of FIGURES 4, 5 and 6 with t11e upper electrodes groundecl is superior to other arrangements of horizontal electrodes in respect to safety. ~o matter how the biplate rows are energized and grounded (such as upper electrode energized and lower electrode grounded, vice versa or both symmetrically driven in respect to ground) leakage currents will flow near the surface 24 that may ~e small but significant in respect to safety and equipment protection. l~ese currents will create field gradients which, although small, can be sufficient to develop hazardous potentials on surface or near-surface objects 68, such as pipelines, fences and other long metallic structures, or may destroy operation of above-ground electrical equipment. To mitigate such effectsr ground mats can be employed near metallic structures to assure zero potential drops between any meta]lic structures likely to be touched by anyone.
These safety ground mats as well as electrical system grounds will collect the stray current from the biplate array. These grounds then serve in effect as additional ground electrodes of a line. Leakage ~2Z~L0~i4 currents between the grouncling apparatus at the surface and the biplate array also heat the overburden, especially if the uppermost row is exci-tecl and the deposit is shallow. Thus hiplate arrays, althollgh having two sets of electrodes of large areal extent, also implicitly contain a third but smaller set of electrodes 68 near tne surface a-t grouncl potential.
,~lthough this third set of e]ectrodes collects diminished currents, the design considerations previously discussed to prevent vaporlzat-ion of water in the earth adjacen-t the other electrodes must also be applied.
The near surface ground currents are minimize~
if the upper electrodes 34 are grounded ancl the lower electrodes 36 are energized. Also the grounded upper electrodes 34 can be extended in length and wlrlth to provide adcled shielding. This requires placing procluct collection apparatus at the potential of the energized lower set of electrodes by means of isolation insulation. However, this arrangement reduces leakacle energy losses as compared to other electrodes energizing arrangements. Such leakage currents tend to heat the overburden 2~ between the row of upper electrodes 34 and the above-ground system 6~, giving rise to unnecessary heat losses.
Short heating times stress the equipment, and therefore, the longest heating times consistent with reasonable heat losses are desirable. I~is is especially true for the horizontal biplate array. The conductors of an array in the biplate configuration, especially if it is fairly long, will inject or collect considerable current. The amount of current at the feed point will be proportional to the product of the conductor length Q, the distance d between electrodes within the row, and the current density J needed to heat the deposit to the required temperature in time t. Thus ~2Zl~ 4 the current I per condllctor becomes a-t the feed point (asswning small attenuation along the line):
I = (J) (Q) (cl) Note that J = [(~oules-to-heat)t-] /
and t = c(h/2) so tha t - I ~(joules-t-heat)Cl]c ] / (Q)(-l) C ( h/ 2 ) where c~ is the conductivity of the reservoir and joules-to-heat is the energy requirec1 to heat a cubic meter to the desired temperature. Thus the current carryincJ requirement of the concluctors at the feecl ~oints is reclucecl b~ increasing the heat up time t as determined by the maximum allowable temperature profile factor c ancl deposit thickness 'n. Further, making the array more dense, that is, decreasing cl, also reduces the current carrying requirements as well as decreasing Q. If conductor current at the feed point is excessive, heat will be generated in the electroae clue to I R losses along the conductor. The power dissipated in the electrode due to I2~ losses can significantly exceed the power dissipated in the reservoir immediately adjacent the electrode. This can cause excessive heating of the electrode in addition to the excess heat generated in the adjacent formation clue to the concentration of current near the electrocle.
Thus another criterion is that the I2R concluctor losses not be excessive compared to the power clissipated in the media due to narrowing of the current flow paths into the electrodes. Also the total collected current should not exceed the current carrying rating of the cable .eed systems.
Another cause oE excess temperature of the electrocles over that for the deposit arises from fringing fields near the sides of the row of excited electrodes. Here the outermo~t electrocles (in a ....
. .
1~2Z1~4 direction transverse to the electrode axis) carry additional charges and currents associa~ed with the fringing fields. As a consequence, both the ac1jacent reservoir dissipation ancl I2R Longituclir1al conductor losses will be significantly increased over those experienced for electrodes more central]y located. To control the temperature of these outermost electro~1es, several methods can be used, including: l) increasing the density of the array in the ou-termost regions, 2) relying on additional vaporization to cool these electrodes, and 3) enlarging the diameter of these electrocles. Some cooling benefit will also exist for the cool-wall approac1l, especially in the case of t~e vertical electrocle arrays if an additional portion of the deposit can be includecl in the reduced field region near the outermost electrodes. Applying proqressively smaller potentials as the outermost elec-trodes are neared is another option.
In the case of the biplate array, especially if it extends a great length into the deposit, such as over lOOm, special attention must be given to the path ]osses along the line. I'o alleviate the effects of such attenuation, the line may be fed from both ends, as shown in FIGURE G. At the higher fre~uencies, these are frequency dependent and are reduced as the frequency ;s decreased. Perhaps not appreciated in earlier work, is that there is a limit to how much the path attenuation can be reduced hy lowering the frequency. The prohlem i5 aggravated because, as the deposit is heated, it becomes more conducting.
A buried hip~ate array or triplate array exhibits a path loss attenuation ~ of ~ = 8.7 [(P~+j~L)(G~j~C)] / dB/m where R is the series resistance per meter of the buried line, which includes an added resistance contribution from skin effects in the conductor, if present, o~
L is tne series inductance per met~ o ~ u~ie~' line, G is the shunt conductance over a -e~er for -e line and is direc'ly propor.ional to 5, ~ ce-.a~_-ti~.~i'_v of the deposit, C is the shunt capaci.ance over a meter for .'se -line. ~;~ere conduction currents dominate, G>>~c, so that the attenuation ~ becomes ~ = 8.7 [(R+j~L)(G)]l/2 c13/-If the freauency ~ is reduced, ,~L is r~ i~?.ll~
reduced, R is partially decreased (owing to a reduc'ion in skin effect loss contribution) and G tends to remain more or less constant. Eventually, as frequ~nc~ ~ is decreased, R>>j~L, usually at a near zero frequencv condition, so that = 8.7 ~(~)(G)]l/2 ~.B/m If thin wall steel is used as the electrode material, unacceptable attenuation over fairlY lonq path lengths could occur, especially at the hig~er - 20 temperatures where conductance G and conductivity a are greater. If thin walled copper or aluminum is used for electrodes (these may be clad with steel to resist corrosion), the near zero-frequency attenuation can be acceptably reduced so that aQ = 8.7 [(R)(G)]1/2 (Q) < 2d~
for the single end feed of FIGURE 4 and less than 8dB
~; for the double end feed of FIGURE 6.
When d.c. power is applied, advantage may ~e taken of electro-osmosis to promote the production of liquid hydrocarbons. In the case of electro-osmosis, water and accompanying oil drops are usually attracted to the negative electrodes. ~le fac~ors affecting electro-osmosis are determined in part by the zeta potentials of the formation rock, and in some limited cases the zeta potentials may be such that ~ater and oil are attracted to the positive potentia] electrodes.
1~29~.,i4 ~ lectro-osmosis can also he used to cause slow migra-~ion of -the reservoir water toward one of the sets of electrodes preferentially. This preEerential migration wil] be toward the cathode for typical reservoirsO ~Iowever, depending upon the salinitY of t'ne reservoir fluids and the mineralogy of the reservoir matrix, the net movement uncler application of cl.c. can be toward the anocle. Remote ground can be used as an opposing electrode to facilitate this. Thi.s can be used to replenish conductivity in formations around the desired electrodes of sets of e]ectrodes hy resaturatinc the formation using reservoir fluids. This wil] permit resumption of heating.
In some cases, the presence of water fllls -the available pore spaces and thereby suppresses the flow of oil. Also in the case of a heavy oil ~eposit, influ~ of water from the lower reaches of the deposit may reach the proclucing electrodes such as electrodes 36 (FIGURE 6). Therefore, in some cases it may he desirable to place a potential onto both sets of electrodes 34, 36 such that water is drawn away from the array. ~his may be done by modifying the source 3~ such that the ground electrode arxay ~8 near the surface is p]aced at a negative poiential with respect to the entire set of deep electrodes 34, 36.
D.c. power applied for electro-osmosis can cause anodic dissolution of the metal electrodes, and hence, it will be preferahle to keep the d.c. power levels just high enough to cause miqration of flulds.
Such required d.c. power can either be added as a bias to a.c. power which provides the bulk of the energy required to heat the formation or be applied intermittently.
~hile the use of e]ectro-osmotic effects to enhance recovery from single wells or pairs of wells has been describecl, the employment of the dense array offers unique features heretofore unrecognizecl. For example, ~22~
- 1.7 -in the case of a pai.r of electrocles widely separated, the direct current emerges radiall~7 or spherically from the electrode. The radiallY divergent curren-t produces a radially divergent electric field, and since the electro-osmotic e-ffect is proportional to the electric fielcl, the heneficial effec-ts of electro-osmosis are evident only very near the electrocle. Further~ore, the amollnt of current which can be introduced by an electrode is restricted by vaporization consiclerations 1.0 or, if the deposit is pressurized, by a hiqh temperature colsiny condition which may pluy the producing capillary paths. On the o-ther hand, with the arrangement of the present invention, the large electrode surface area and the controlled temperature below the vaporiza-tion point allows substan-tially more cl.c. current to be introduced. Further, the effects of electro-osmosis are felt throughout the deposit, as uniform current Elow and electric Eielcls are established throughout the bulk of the deposit. Thus an electro-osmotic fluid drive phenomenon oE su~stantial magnitucle can be establis11ed throughou-t the deposit which can substantially enhance the procluction ra-tes.
Further, electrolyte fluicls will be drawn out o-f the electrocdes which are not used to coll.ect the water. Therefore, means to replace this electrolyte must be provided.
Production of liquid hyclrocarbons using electro-osmosis can also be practiced in combination with conventional recovery -techniq~es such as gravity drainaye. Electro-osmosls can be used to increase the rate of produc-tion o:E liquld hydrocarbons by gravity drainaye. For example, the polarit~ of the electrocle rows shown in FI~URE 5 can be so chosen such tha-t reservoir water will slowly move toward the upper ro~ of electrodes 34. This will cause a simultaneous increase in saturation of hydrocarbons toward the bottom row of elec-trocles 36. The rate of flow of hydrocarbons toward ~ %~ 4 these bottom electrodes 36 is directly proportional to the permeability of the formation near the elec-trodes to flow of h~drocarbons. ~'his in turn increases with increase in hyclrocarbon saturation. Thus, the rate of hydrocarbon prod11ction can be increased by forcing the reservoir water to move toward the upper part of the formation by electro-osmosis.
Althoug11 various preferred embodiments of the present invention have been described in some ~1etail, various modifications may be made therein within the scope oE the invention.
Several methods of production are possible beyond the unique features o~ electro-os~c~sis.
Typically, the oi] can be recovered via qravity or lS autogenously generated vapor drives into the perforated electrodes, which can serve as product collection paths. Provision for this type of procluct collection i9 illustrated in FIGURE 4, where a positive displacement pump 66 located in the lowest level of electrode 36 can be used to recover the product. Product can be collected in some cases during the heat-up period. For example, in FIGURE 4 the reservoir fluids will tencl to collect in the lower electrode array. If those are produced during heating, those fluids can provicle an additional or substitute means to control the temperature of the lower electrode. On the ot~er hand, it may not be desirable to produce a deposit, if ln situ cracking is planned, until the final temperature is reached.
Various "hybrid" production combinations may he considered to produce the deposit after heating. These could include fire-floods, steam flocds and surfactant/polymer water floods. In these cases, one row of electrodes can be used for fluid injections and the adjacent row fox fluid/product recovery.
In contrast with polarizing the electrodes so as to suppress the production of water, the ~2;2~0~
- 19 ~
electro-osmotic forces can be used as a drive mechanism whic11 exists volumetrically t~1roucJhout the deposit for a fluid replacement type flood. The principal henefits of using the electro-osmotic drive in conjunction with the electrode arrays discussed here is that the vo]uTnetric drive can be maintainecl without excessive heat being developed near the electrocle or without excessive electrolysis as might occur in a simple five-spot well arrangement.
The fluids injected at the electrocles can contain surfactants such as long chain sulfonates or amines or polymers such as polyaerylamides. The presence o~ surfactant~ will re~uce the interfacia]
tension between the injectecl fluic1s and the liquid hydrocarbons ancl will help in recovering the liqu;cl hycdrocarbons. Ad~1ition of polymers will increase the viscosity and cause an improvement in sweep efficienc~.
T1le applied d.c. power can act as the driving force for the migration of fluids towarcl the other set o electrodes, whereby the accompanying liquid hydrocarhons can be produced along with the drive fluid.
The foregoing discussion, for simplicity, has limited consideration to either vertical or horizonta]
electrode arrays. However, arrays employed at an angle with respect to the deposit may be useful to minimize the number of drifts and the number of horeholes. In this ease, the maximum row separation s is chosen to he midway between the vertical or horizontal situation, such that if largely vertical, the row separation s is not much greater than that found for the true vertical case. On the other hand, if the rows are nearly horizontal, then a va]ue of s closer to that chosen for a horizontal array should be usecl.
EL~C'rRO-OSMOTIC PF~ODUCTION OF HYDP~OCARP,~NS U~ILIZI~G
CONDUCI'IOL~ HEATING OF ~YDROC~RBONACEOU5 FORMATIONS
BACKGROU~D OF THE I~VENTIO~
~This invention relates generally to the exploitation of hydrocarl~on-bearing formations having substantial electrieal conductivity, such as t~r sands and heavy oil deposits, by the applica-tion of eLectrical eneryy to heat the deposits. More specifically, the invention relates to the delivery of electrical power to a eonductive -formation at relatively low frequenc~ or d.c., whicll po~er is appliecl between rows of elongatec~
electrodes forming a waveguide structure bol1nding a particular volume of the formation, while at the same time the temperature of the eleetrodes is controlled.
Materials such as tar sands and heavy oil deposits are amenable to heat processing to produce gases and hydrocarbons. Generally the heat develops the porosity, permeability ancl/or mobility neeessary for reeovery. Some hydrocarbonaceous materials may be reeovered upon pyrolysis or distillation, others simply upon heating to inerease mobility.
Materials such as tar sands and heavy oil deposits are heterogeneous dieleetries. Sueh dielectric media exhibit very large values of conduetivity, relative dieleetrie eonstant, and loss tangents at low temperature, but at high temperatures exhibit lower values for these parameters. Such behavior arises beeause in sueh media, ionie eonducting paths or layers are established in the moisture contained in the interstitial spaces in the porous, relatively lo~
dieleetric eonstant and loss tangent rock matrix. IJpon heating, the moisture evaporates, l~hich radically reduces the bulk conductivity, relative clielectrie eonstant, and loss tangent to essentially that of the roek matrix.
It has been known to heat eleetrieally relatively large volumes of hydroearbonaeeous formations .,h ~221~5~
in si-tu. Briclges ancl Taflove Vnited States Reissue Patent No. Re. 30,73~ cliscloses a system and method for such ln _tu heat processing of llydrocarbonaceous earth formations wherein a plurality of elongated electrodes are inserted in formations and bound a particu]ar volume of a formation of interest. As used therein, the term "bounding a particular formation" means that the volume is enclosed on at least two sides thereof. The enclosed sides are enclosecl in an electrical sense with a ro-~l of cliscrete electrodes forming a par-ticular side.
Electrical excitation between rows of S-lCh electrodes established electrical fie]ds ;n the volume. As disclosed in such patent, the frequency of the excitation was selected as a function of the bollnded volume so as to establish a substantially nonradiating electric field which was confined substantially in the volume. The method and system of the reissue patent have particular application in the radio-frequency heating of moderately lossy dielectric formations at relatively high frequency. However, it is also useful in relatively lossy dielectric formations where relatively low frequency electrical power is utilizecl for heating largely by conduction. The present invention is directecd toward the improvement of such method and system for such heating of relatively conductive formations at relatively low frequency an~ to the application of such system for heating with d.c.
SUM~ARY OF THE IN~ENTION
An electro-osmotic method for the production ~f hydrocarbons utilizes in situ heating of earth for~ations having substantial electrical conductivity occasioned by the presence of water. A particular volume of an earth formation is bouncled with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array with the spacing between rows greater than the distance between electrodes in a row wherein the active electrode area ~2~1~5~
and tne row separation are chosen in reference to the formation thickness to avoid heating barren layers, the row separation being no greater than about the thickness of the formation. Electrical power is applied at no more than a relatlvely low frequency between respectlve rows of electrodes to dellver power to the houndecl volume of the formatlon wlllle produclng relatively uniform heating -thereof and llmltlng the re]ative loss of heat to adjacent reglons. A d.c. polari~ed potentlal is utilized to make the electrodes of one row anodlc and the electrodes of another row cathodic ancl thereby enhance the flow of reservoir fluid toward at least one preselecte-1 electrode. At the same time the temperature of the electrocles ls controlled to retain water and thereby maintain an electrically condllctive path between the electrodes and the formation. Reservolr flulds that have flowed between the rows toward the at least one preselected electrode are removed.
In one aspect of the invention a remote qround is used for cathodic contact.
These and other aspects and advantages of the present invention will become more apparent -from the following detailed description, partlcularly when taken in conjunction with the accompanying drawings.
~RIEF DESCRIPTIO~ OF THE DRAWINGS
FIGURE 1 is a vertical sectional view, partly diagrammatic, of a preferred em~odiment of a system for the conductive heating of an earth formation in accordance with t~e present invention, wherein an array of electrodes is emplaced vertically, the section belnq taken transversely of the rows of elec-trodes;
FIGURE 2 is a diagrammatlc plan view of the system shown in FIGURE l;
FIGURE 3 is an enlarged vertical sectional view, partly diagrammatic, of part of the system shown in FIGUR~ l;
~2210S~
. 4 FIGURE 4 is a vertica:L sectional view, partly diayramma~ic, of an alternative system for the conductive heating of an earth forTnati.on in accorclance with the presen-t invention, wherein an array of electrodes is emplaced hori~ontally, the section being taken longitudinally of the electrodes;
FIGURE 5 is a vertical sectional view, partly diagrammatic of the system shown in FIGURR ~, talcen along line 5-5 of FIGURr. 4;
FIGURE 6 is a vertical sectional view comparable to that of FIGURE ~ showing an alternative system with hori~ontal electrodes fed fxom both ends;
FIGUP~E 7 is a plan view, mostly diaqrammatic, of an alternative syste~ comparahle to that shown in FIGUXE 3, with cool walls adjacent electrodes;
FIGURE 8 is a vertical sectional view, part].y diagrammatic of the system shown in FIGURE 7, taken along line 8-8 of FIGURE 7;
E'IGURE 9 is a set of curves showing the relationship between a time dependent factor c and heat loss and a function of deposit temperature utilizing the present invention;
FIGURE 10 is a set of curves showing the temperature distribution at different heating rates when heat is delivered to a defined volume;
FIGURE 11 is a set of curves showing the relationship between time and temperature at different points when a formation is heated by a sparse array;
FIGURE 12 is a set of curves showin~ the relationship between time and temperature at ~ifferent points when a formation is heated in accordance with the present invention with electrode diameters of 32 inches;
and FIGURE 13 is a set of curves showing the relationship of time and temperature at the same points as in FIG~RE 12 in accordance with the present invention with electrode diameters of 1~ inches.
~2~S~
DETAIJ~ DESCRIPTIOi~, OF T~-IE PREFERRED EI~ODIMFNTS
, FIGURES 1, 2 and 3 i]lustrate a syste~ for heating conductive formations utilizing an array 10 of vertical electrodes 12, 14, the electrocles 12 beinq 5 grounded, ancl the electrodes 14 being enerqized by a low frec~uency or d.c. scurce 16 of electrical power by means of a coaxial line 17. r~le electrodes 12, 14 are disposed in respective parallel rows spacecl a spacing s apart with the electrodes spacecl apart a distance d in the respective rows. The electrode array 10 is A dense array, meaning tllat the spacing 5 between rows is greater than the distance _ between e]ectrodes in a row. The rows of electrocles 12 are longer than the rows of electrodes 14 to con~ine t~e electric fiel~s an~
consequent heating at the ends of the rows of electrodes 14.
The electrodes 12, 14 are tubular electrodes emplaced in respective boreholes 18. The electrodes may be emplacecl from a minecl drift 20 accessed through a shaft 22 from the surface 24 of the earth. rFhe electrodes 12 preferably extencl, as .shown, t11rougl~ a deposit 26 or earth formation containing the hydrocarbons to be produced. The electrodes 12 extend into the overburden 28 above the deposit 26 and into the 25 underburden 30 below the deposit 26. The electrodes 14, on the other hand, are shorter than the electrodes 12 and extend only part way through the deposit 26, short of the overburden 28 and underburden 30. In order to avoid heating the underburden and to provide the power connection, the lower portions of the electrodes 1~ may be insulated from the formations by insulators 31, which may be air. The effective lengths o-f the electrodes 14 therefore end at the insulators 31.
FIGURES 4 and 5 illustrate a system for heatinq conductive formations utilizing an array 32 o~
horizontal electrodes 34, 36 disposed in vertically spaced parallel rows, the electrodes 34 being in the ,~
lZ21~54 upper row and the elec-trodes 36 in the lower row. The upper electrodes 34 are preferably groundecl, and the lower electrodes 36 are energized by a low frequency or d.c. source 38 of e]ectrical power. I'he electrodes 34, 36 are disposed in parallel rows spaced apart a spacing s, t~ith the electrodes spaced apart a clistance d in the respective rows. rne electrode array 32 ls also a dense array. The upper row of electrodes 34 is longer than the lower row of electrodes 3~ to confine the electric fields from the electrodes 36. The electrodes 3~ extend beyond both ends of the electrodes 3G for the same reason. Grounding the upper electrodes 34 ]ceeps down stray fielc~s at t11e sur~ace 24 of the earth.
The electrodes 34, 36 are tubular e]ectrodes emplaced in respective boreholes 40 which may be drilled by well ]cnown directional drilling techniques to provide horizontal boreholes at the top and bottom of tlle deposit 2G between the overburden 28 and the underburden 30. Preferably the upper boreholes are at the interface between the deposit 26 and the overburden 28, and tlle lower boreholes are slightly above the interface between the deposit 26 and tihe underburden 30.
FIGURE 6 illustrates a system comparable to that shown in FIGURES 4 and 5 wherein the array is fed from both ends, a second power source 42 being connected at the end remote from the power source 38.
FIGURES 7 and 8 illustrate a system comparable to that of FIGURES 1, 2 and 3 with an array of vertical electrodes. In this system the rows of like electrodes 12, 14 are in spaced pairs to provide a low field region 44 therebetween that is not directly lleated to any qreat extent.
I'he deposit thickness h and the average or effective thermal diffusion properties determine the uniformity of the temperature distribution as a function of heating time t and can be generally described for any ~Z~1~54 thickness oE a deposit in the -terms of a deposit temperature profile factor c, such that c = kt/(h/2) where _ is the thermal diffusivity. FIGURE 9 ~resents a curve ~ showing the relationsh-ip between the factor c and the portion of a deposit above ~0% of the temperature rise oE the center of the deposit for a uniform heating rate through the heated volume. Note that at c = 0.1, about 75% of the heate~ volume 11~S a temperature rise ~Leater tllan ~30% of the temperature rise of the center of the heated volume.
FIGVRE 10 illustrates the heatinq profiles for three values of the factor c as a function of the distance from the center of the heated volume, the fraction of the temperature rise that would have been reached in -the heated ~7Olume in the absence of heat outflow. Note that where c = 0.1 or c - 0.2, the tota]
percentage of heat lost to adjacent formatlons is relatively small, about 10% to 15%. I~here low flnal temperatures, e.g., less than lO0DC, are suitable, c up to 0.3 can be accepted, as the heat lost, or extra heat needed to maintain the final temperature, is, while significant, economically acceptable. FIGURE 9, curve B, showing percent heat loss as a function of the factor c, shows percent heat loss to be less than 25~ at c =
0.3. On the other hand, if higher temperatures (e.q., about 200C) are desired to crack the bitumen, then higher central deposit temperatures above the design minimum are needed to process more of the deposit, especially if longer heating times are employe~l.
Moreover, the heat outflows at these higher temperatures are more economically disadvantageous. Thus a temperature profile factor of c 1ess than about 0.15 is required. In general the heating rate should be great enough that c is less than 30 times the inverse of the ultimate increase in temperature ~T in degrees ce]sius of the volume:
c < 0.3(100/~T) , ~' :~221~54 The lowest values of c are controllecl more l~y the excess temperature oE electxodes and are discllssed 'nelow.
The electrode spacing distance d and diameter a are determined by the maximum allowal~le electrocle temperature plus some excess if some local vaporization of the electrolyte ancl connate water can be tolerate-l.
In a reasonably dense array, t'ne hot regions aroun~ t'ne electrodes are confined to the immediate vicinity of the electrodes. On the other hand, in a sparse array, where s is no greater than d, the excess heat zone comprises a major portion of the deposi-t.
FIGURE ll i llustrates a gross]y excessive heat bulld-up on the electrodes as compared to the center of ~l~e deposit for a sparse array. In this exaJ~p1e ro~Y
spacing s was lOm, electrode spacing cl ]Om, electrode dlameter a 0.8m, and thermal diffusivity 10 m /s, with no fluid flow.
FIGURE 12 sho~s how the electrode temperature can be reduced by the use of a dense array. In this example row spacing s was lOm, electrode spacing d 4m, electrode diameter a O.~,m, and thermal diffusivity m2/s, with no fluid flow.
FIGURE 13 illustrates the effect of decreasing the diameter of the electrodes of the dense array of FIGURE 12 such that the temperature of the electrode is increased somewhat more re]ative to the main cleposit.
In this example row spacing s was lOm, electrode spacing d 4m, electrode diameter a 0.35m, and thermal diffusivity 10 6 m /s, with no fluid flow. The region of increased temperature is confined to the immediate vicinity of the electrode and does not constitute a major energy waste. ~lIIS, varying the electrode separation distance d and the diameter of the electrode a permlt controlling the temperature of t~e electrode either to prevent vapori~.ation or excessive vaporiæation of the electrolyte in the borehole and .,, ,. ~ . i, ~z~s~
connate water in the formations immediately acljacent the electrode.
The electrode spacing _ and diameter a are cllosen so that either electrode temperature is comparable to the vaporization temperature, or if some local vapori7.ation is tolerahle (as for a moderately den~e array), the unmodified electrode temperature rise without vapor cooling will not significantly exceed the vaporization temperature~
The means for providing water for hoth vaporization and for maintenance of electrical conduction is shown in the drawings, particularly i.n FIGUl~E 3 for vertical electrodes and in FIGURÆ 4 for llorizontal electrodes. As shown ln FIGURE 3, a reservoir ~6 of aclueous electrolyte provides a conductive solution that may be pumpecl by a flow regulator and pump 47 down the shaft 22 and up the interior of the electrodes 12 and into the spaces between the electrodes 12 and the forma-tion 2G. A vapor relief pipe 48, together with a pressure regulator and pump 50 returns excess electrolyte to the reservoir 46 and assures that the electrolyte always covers the electrodes 12. Similarly, a reservoir 52 provides sucll electrolyte down the shaft 22, whence it is driven by a pressure regulator and pump 53 up the interior of the electrodes 14 and into the spaces between the electrodes 14 and the formation 26. In this case the electrodes are energi~ed and not at ground potential. The conduits 54 carrying the electrolyte through the shaft 22 are therefore at the potential of the power supply an~ mllst be insulated from ~round, as is the reservoir 52. The conduits 54 are therefore in the central conductor of the coaxial line 17. The electrodes 14 have corresponding vapor relief pipes 56 and a related pressure reyulator and pump 58.
~ s shown in FIGU~E 4, electrolyte is provided as needed from reservoirs 60, 61 to the interior tubing ~2ZlC~;4 62 which also ac~s to connect the power source 38 to t'he respective electrodes 34, 36, the tubing being insulated from the overburden 28 ancl the deposit 26 hy insulation 64. The elec-trolyte goes down the tubing 62 to kee~ the spaces between the respective electrocles ~4, 36 and the deposit 26 full of conductive solution during heating.
The tubing to t'he lower electrode 36 may later be used to pump out the oil entering the lower electrode, using a positive dis,~lacement pump G6.
In either system, the electrolyte acts as a heat sink to assure cool electrodes and maintain conductive paths between the respective electrocles and the deposit. '~'~e water in the electrolyte may hoi] an~
thereby absorb heat to cool tlle electrodes, as the water is replenished~
The vaporization temperature is controllecl hy the maximu~ sustainable pressure of the deposit.
Typically for shallow to moderate depth deposits the gauge pressure can range from a few psig to 300 psig with a maximum of about 1300 psig for practical systems. The tightness of ad~acent formations also influences the maximum sustainable vapor pressure. In some cases, injection of inert gases to assist in maintaining de~osit pressure may be needed.
Another way to keep the electrodes cool is to position the electrodes adjacent a reduced field region on one side of an active electrode row. This reduces radically the heating rate in the region of the diminished field, thus creating in effect a heat sink which radically reduces the temperature of the electrodes, in the limiting case to ahout half the temperature rise of the center portion of the deposit.
As shown in FIGUR~S 7 and 8, in the case of vertical arrays, pairs of electro-]es 12, 14 can be installed from the same drift and the same potential is applied to each pair, thus the regions 44 between the pairs become low field regions. By proper selection of pZZ10~4 heating rates and pair separation, it is possible to control the temperature of the electroc1e at slightly below that for the cen-ter of the cleposit. The thickness of the cool wall region 44 can be sufficiently thin that the cool wall region can achieve a~out 90% of the maximum deposit temperature via therma] diffusion from the heated volume after -the application of power has ended.
A~ shown in F~GUR~S 4, 5 and 6 in the case of a horizontally enlarged biplate, a near zero field region exists on the barren side of the row of grounded upper electrodes 34 and a near zero field region exists on the barren si~e of the row of energize~ electro~es 36. Suc~
low field regions act as the regions 44 in the svstem shown in FI&~RES 7 and 8.
The arrangement of FIGURES 4, 5 and 6 with t11e upper electrodes groundecl is superior to other arrangements of horizontal electrodes in respect to safety. ~o matter how the biplate rows are energized and grounded (such as upper electrode energized and lower electrode grounded, vice versa or both symmetrically driven in respect to ground) leakage currents will flow near the surface 24 that may ~e small but significant in respect to safety and equipment protection. l~ese currents will create field gradients which, although small, can be sufficient to develop hazardous potentials on surface or near-surface objects 68, such as pipelines, fences and other long metallic structures, or may destroy operation of above-ground electrical equipment. To mitigate such effectsr ground mats can be employed near metallic structures to assure zero potential drops between any meta]lic structures likely to be touched by anyone.
These safety ground mats as well as electrical system grounds will collect the stray current from the biplate array. These grounds then serve in effect as additional ground electrodes of a line. Leakage ~2Z~L0~i4 currents between the grouncling apparatus at the surface and the biplate array also heat the overburden, especially if the uppermost row is exci-tecl and the deposit is shallow. Thus hiplate arrays, althollgh having two sets of electrodes of large areal extent, also implicitly contain a third but smaller set of electrodes 68 near tne surface a-t grouncl potential.
,~lthough this third set of e]ectrodes collects diminished currents, the design considerations previously discussed to prevent vaporlzat-ion of water in the earth adjacen-t the other electrodes must also be applied.
The near surface ground currents are minimize~
if the upper electrodes 34 are grounded ancl the lower electrodes 36 are energized. Also the grounded upper electrodes 34 can be extended in length and wlrlth to provide adcled shielding. This requires placing procluct collection apparatus at the potential of the energized lower set of electrodes by means of isolation insulation. However, this arrangement reduces leakacle energy losses as compared to other electrodes energizing arrangements. Such leakage currents tend to heat the overburden 2~ between the row of upper electrodes 34 and the above-ground system 6~, giving rise to unnecessary heat losses.
Short heating times stress the equipment, and therefore, the longest heating times consistent with reasonable heat losses are desirable. I~is is especially true for the horizontal biplate array. The conductors of an array in the biplate configuration, especially if it is fairly long, will inject or collect considerable current. The amount of current at the feed point will be proportional to the product of the conductor length Q, the distance d between electrodes within the row, and the current density J needed to heat the deposit to the required temperature in time t. Thus ~2Zl~ 4 the current I per condllctor becomes a-t the feed point (asswning small attenuation along the line):
I = (J) (Q) (cl) Note that J = [(~oules-to-heat)t-] /
and t = c(h/2) so tha t - I ~(joules-t-heat)Cl]c ] / (Q)(-l) C ( h/ 2 ) where c~ is the conductivity of the reservoir and joules-to-heat is the energy requirec1 to heat a cubic meter to the desired temperature. Thus the current carryincJ requirement of the concluctors at the feecl ~oints is reclucecl b~ increasing the heat up time t as determined by the maximum allowable temperature profile factor c ancl deposit thickness 'n. Further, making the array more dense, that is, decreasing cl, also reduces the current carrying requirements as well as decreasing Q. If conductor current at the feed point is excessive, heat will be generated in the electroae clue to I R losses along the conductor. The power dissipated in the electrode due to I2~ losses can significantly exceed the power dissipated in the reservoir immediately adjacent the electrode. This can cause excessive heating of the electrode in addition to the excess heat generated in the adjacent formation clue to the concentration of current near the electrocle.
Thus another criterion is that the I2R concluctor losses not be excessive compared to the power clissipated in the media due to narrowing of the current flow paths into the electrodes. Also the total collected current should not exceed the current carrying rating of the cable .eed systems.
Another cause oE excess temperature of the electrocles over that for the deposit arises from fringing fields near the sides of the row of excited electrodes. Here the outermo~t electrocles (in a ....
. .
1~2Z1~4 direction transverse to the electrode axis) carry additional charges and currents associa~ed with the fringing fields. As a consequence, both the ac1jacent reservoir dissipation ancl I2R Longituclir1al conductor losses will be significantly increased over those experienced for electrodes more central]y located. To control the temperature of these outermost electro~1es, several methods can be used, including: l) increasing the density of the array in the ou-termost regions, 2) relying on additional vaporization to cool these electrodes, and 3) enlarging the diameter of these electrocles. Some cooling benefit will also exist for the cool-wall approac1l, especially in the case of t~e vertical electrocle arrays if an additional portion of the deposit can be includecl in the reduced field region near the outermost electrodes. Applying proqressively smaller potentials as the outermost elec-trodes are neared is another option.
In the case of the biplate array, especially if it extends a great length into the deposit, such as over lOOm, special attention must be given to the path ]osses along the line. I'o alleviate the effects of such attenuation, the line may be fed from both ends, as shown in FIGURE G. At the higher fre~uencies, these are frequency dependent and are reduced as the frequency ;s decreased. Perhaps not appreciated in earlier work, is that there is a limit to how much the path attenuation can be reduced hy lowering the frequency. The prohlem i5 aggravated because, as the deposit is heated, it becomes more conducting.
A buried hip~ate array or triplate array exhibits a path loss attenuation ~ of ~ = 8.7 [(P~+j~L)(G~j~C)] / dB/m where R is the series resistance per meter of the buried line, which includes an added resistance contribution from skin effects in the conductor, if present, o~
L is tne series inductance per met~ o ~ u~ie~' line, G is the shunt conductance over a -e~er for -e line and is direc'ly propor.ional to 5, ~ ce-.a~_-ti~.~i'_v of the deposit, C is the shunt capaci.ance over a meter for .'se -line. ~;~ere conduction currents dominate, G>>~c, so that the attenuation ~ becomes ~ = 8.7 [(R+j~L)(G)]l/2 c13/-If the freauency ~ is reduced, ,~L is r~ i~?.ll~
reduced, R is partially decreased (owing to a reduc'ion in skin effect loss contribution) and G tends to remain more or less constant. Eventually, as frequ~nc~ ~ is decreased, R>>j~L, usually at a near zero frequencv condition, so that = 8.7 ~(~)(G)]l/2 ~.B/m If thin wall steel is used as the electrode material, unacceptable attenuation over fairlY lonq path lengths could occur, especially at the hig~er - 20 temperatures where conductance G and conductivity a are greater. If thin walled copper or aluminum is used for electrodes (these may be clad with steel to resist corrosion), the near zero-frequency attenuation can be acceptably reduced so that aQ = 8.7 [(R)(G)]1/2 (Q) < 2d~
for the single end feed of FIGURE 4 and less than 8dB
~; for the double end feed of FIGURE 6.
When d.c. power is applied, advantage may ~e taken of electro-osmosis to promote the production of liquid hydrocarbons. In the case of electro-osmosis, water and accompanying oil drops are usually attracted to the negative electrodes. ~le fac~ors affecting electro-osmosis are determined in part by the zeta potentials of the formation rock, and in some limited cases the zeta potentials may be such that ~ater and oil are attracted to the positive potentia] electrodes.
1~29~.,i4 ~ lectro-osmosis can also he used to cause slow migra-~ion of -the reservoir water toward one of the sets of electrodes preferentially. This preEerential migration wil] be toward the cathode for typical reservoirsO ~Iowever, depending upon the salinitY of t'ne reservoir fluids and the mineralogy of the reservoir matrix, the net movement uncler application of cl.c. can be toward the anocle. Remote ground can be used as an opposing electrode to facilitate this. Thi.s can be used to replenish conductivity in formations around the desired electrodes of sets of e]ectrodes hy resaturatinc the formation using reservoir fluids. This wil] permit resumption of heating.
In some cases, the presence of water fllls -the available pore spaces and thereby suppresses the flow of oil. Also in the case of a heavy oil ~eposit, influ~ of water from the lower reaches of the deposit may reach the proclucing electrodes such as electrodes 36 (FIGURE 6). Therefore, in some cases it may he desirable to place a potential onto both sets of electrodes 34, 36 such that water is drawn away from the array. ~his may be done by modifying the source 3~ such that the ground electrode arxay ~8 near the surface is p]aced at a negative poiential with respect to the entire set of deep electrodes 34, 36.
D.c. power applied for electro-osmosis can cause anodic dissolution of the metal electrodes, and hence, it will be preferahle to keep the d.c. power levels just high enough to cause miqration of flulds.
Such required d.c. power can either be added as a bias to a.c. power which provides the bulk of the energy required to heat the formation or be applied intermittently.
~hile the use of e]ectro-osmotic effects to enhance recovery from single wells or pairs of wells has been describecl, the employment of the dense array offers unique features heretofore unrecognizecl. For example, ~22~
- 1.7 -in the case of a pai.r of electrocles widely separated, the direct current emerges radiall~7 or spherically from the electrode. The radiallY divergent curren-t produces a radially divergent electric field, and since the electro-osmotic e-ffect is proportional to the electric fielcl, the heneficial effec-ts of electro-osmosis are evident only very near the electrocle. Further~ore, the amollnt of current which can be introduced by an electrode is restricted by vaporization consiclerations 1.0 or, if the deposit is pressurized, by a hiqh temperature colsiny condition which may pluy the producing capillary paths. On the o-ther hand, with the arrangement of the present invention, the large electrode surface area and the controlled temperature below the vaporiza-tion point allows substan-tially more cl.c. current to be introduced. Further, the effects of electro-osmosis are felt throughout the deposit, as uniform current Elow and electric Eielcls are established throughout the bulk of the deposit. Thus an electro-osmotic fluid drive phenomenon oE su~stantial magnitucle can be establis11ed throughou-t the deposit which can substantially enhance the procluction ra-tes.
Further, electrolyte fluicls will be drawn out o-f the electrocdes which are not used to coll.ect the water. Therefore, means to replace this electrolyte must be provided.
Production of liquid hyclrocarbons using electro-osmosis can also be practiced in combination with conventional recovery -techniq~es such as gravity drainaye. Electro-osmosls can be used to increase the rate of produc-tion o:E liquld hydrocarbons by gravity drainaye. For example, the polarit~ of the electrocle rows shown in FI~URE 5 can be so chosen such tha-t reservoir water will slowly move toward the upper ro~ of electrodes 34. This will cause a simultaneous increase in saturation of hydrocarbons toward the bottom row of elec-trocles 36. The rate of flow of hydrocarbons toward ~ %~ 4 these bottom electrodes 36 is directly proportional to the permeability of the formation near the elec-trodes to flow of h~drocarbons. ~'his in turn increases with increase in hyclrocarbon saturation. Thus, the rate of hydrocarbon prod11ction can be increased by forcing the reservoir water to move toward the upper part of the formation by electro-osmosis.
Althoug11 various preferred embodiments of the present invention have been described in some ~1etail, various modifications may be made therein within the scope oE the invention.
Several methods of production are possible beyond the unique features o~ electro-os~c~sis.
Typically, the oi] can be recovered via qravity or lS autogenously generated vapor drives into the perforated electrodes, which can serve as product collection paths. Provision for this type of procluct collection i9 illustrated in FIGURE 4, where a positive displacement pump 66 located in the lowest level of electrode 36 can be used to recover the product. Product can be collected in some cases during the heat-up period. For example, in FIGURE 4 the reservoir fluids will tencl to collect in the lower electrode array. If those are produced during heating, those fluids can provicle an additional or substitute means to control the temperature of the lower electrode. On the ot~er hand, it may not be desirable to produce a deposit, if ln situ cracking is planned, until the final temperature is reached.
Various "hybrid" production combinations may he considered to produce the deposit after heating. These could include fire-floods, steam flocds and surfactant/polymer water floods. In these cases, one row of electrodes can be used for fluid injections and the adjacent row fox fluid/product recovery.
In contrast with polarizing the electrodes so as to suppress the production of water, the ~2;2~0~
- 19 ~
electro-osmotic forces can be used as a drive mechanism whic11 exists volumetrically t~1roucJhout the deposit for a fluid replacement type flood. The principal henefits of using the electro-osmotic drive in conjunction with the electrode arrays discussed here is that the vo]uTnetric drive can be maintainecl without excessive heat being developed near the electrocle or without excessive electrolysis as might occur in a simple five-spot well arrangement.
The fluids injected at the electrocles can contain surfactants such as long chain sulfonates or amines or polymers such as polyaerylamides. The presence o~ surfactant~ will re~uce the interfacia]
tension between the injectecl fluic1s and the liquid hydrocarbons ancl will help in recovering the liqu;cl hycdrocarbons. Ad~1ition of polymers will increase the viscosity and cause an improvement in sweep efficienc~.
T1le applied d.c. power can act as the driving force for the migration of fluids towarcl the other set o electrodes, whereby the accompanying liquid hydrocarhons can be produced along with the drive fluid.
The foregoing discussion, for simplicity, has limited consideration to either vertical or horizonta]
electrode arrays. However, arrays employed at an angle with respect to the deposit may be useful to minimize the number of drifts and the number of horeholes. In this ease, the maximum row separation s is chosen to he midway between the vertical or horizontal situation, such that if largely vertical, the row separation s is not much greater than that found for the true vertical case. On the other hand, if the rows are nearly horizontal, then a va]ue of s closer to that chosen for a horizontal array should be usecl.
Claims (29)
1. An electro-osmotic method for the production of hydrocarbons utilizing in situ heating of earth formations having substantial electrical conductivity occasioned by the presence of water, said method comprising bounding a particular volume of a said earth formation with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array with the spacing between rows greater than the distance between electrodes in a row wherein the active electrode area and the row separation are chosen in reference to the formation thickness to avoid heating barren layers, the row separation being no greater than about the thickness of said formation, applying electrical power at no more than a relatively low frequency between respective said rows of electrodes to deliver power to said bounded volume of said formation while producing relatively uniform heating thereof and limiting the relative loss of heat to adjacent regions, and utilizing a d.c. polarized potential to make the electrodes of one row anodic and the electrodes of another row cathodic and thereby enhance the flow of reservoir fluid toward at least one preselected electrode, at the same time controlling the temperature of said electrodes thereat to retain water and thereby maintain an electrically conductive path between said electrodes and said formation, and removing collected reservoir fluids that have flowed between said rows toward said at least one preselected electrode.
2. A method according to Claim 1 wherein said temperature of said electrodes is controlled by providing a heat sink adjacent said electrodes.
3. A method according to Claim 2 wherein said temperature of said electrodes is controlled by conducting heat from said electrodes to a cooler region outside said bounded volume.
4. A method according to Claim 2 wherein said heat sink is provided by supplying aqueous liquid electrolyte to space between said electrodes and the adjacent said formation, thereby maintaining the temperature thereat no greater than about the boiling point of water and maintaining a conductive path between said electrodes and said formation.
5. A method according to Claim 1 wherein a region of reduced electric field intensity is created adjacent said rows of electrodes outside said bounded volume.
6. An electro-osmotic method for the production of hydrocarbons utilizing in situ heating of earth formations having substantial electrical conductivity occasioned by the presence of water, said method comprising bounding a particular volume of a said earth formation with a waveguide structure formed of respective rows of discrete elongated electrodes in a dense array with the spacing between rows greater than the distance between electrodes in a row wherein the active electrode area and the row separation are chosen in reference to the formation thickness to avoid heating barren layers, the row separation being no greater than about the thickness of said formation, applying electrical power at no more than a relatively low frequency between respective said rows of electrodes to deliver power to said bounded volume of said formation while producing relatively uniform heating thereof and limiting the relative loss of heat to adjacent regions, and utilizing a d.c. polarized potential to make the electrodes of one row anodic with the use of a remote ground for cathodic contact and thereby enhance the flow of reservoir fluid toward at least one preselected electrode, at the same time controlling the temperature of said electrodes thereat to retain water and thereby maintain an electrically conductive path between said electrodes and said formation, and removing collected reservoir fluids that have flowed between said rows toward said at least one preselected electrode.
7. A method according to Claim 1 further including injecting electrolyte into said formation adjacent the electrodes in the row other than the row containing said at least one preselected electrode to maintain conduction and replace fluids that have migrated to a product collection electrode.
8. A method according to any one of Claims 2 to 4 further including injecting electrolyte into said formation adjacent the electrodes in the row other than the row containing said at least one preselected electrode to maintain conduction and replace fluids that have migrated to a product collection electrode.
9. A method according to either one of Claims 5 and 6 further including injecting electrolyte into said formation adjacent the electrodes in the row other than the row containing said at least one preselected electrode to maintain conduction and replace fluids that have migrated to a product collection electrode.
10. A method according to any one of Claims 1 to 3 wherein the applied d.c. potential is used to provide substantially all of the energy required to heat the formation to increase the mobility of the hydrocarbons.
11. A method according to any one of Claims 4 to 6 wherein the applied d.c. potential is used to provide substantially all of the energy required to heat the formation to increase the mobility of the hydrocarbons.
12. A method according to Claim 7 wherein the applied d.c. potential is used to provide substantially all of the energy required to heat the formation to increase the mobility of the hydrocarbons.
13. A method according to any one of Claims l to 3 wherein the applied d.c. potential is used both for heating of the formation and for providing an electro-osmotic drive for the recovery of the fluids.
14. A method according to any one of Claims 4, and 7 wherein the applied d.c. potential is used both for heating of the formation and for providing an electro-osmotic drive for the recovery of the fluids.
15. A method according to any one of Claims 1 to 3 wherein a.c. power is applied to provide primary heating of the formation and d.c. potential is utilized as a superimposed bias for providing electro-osmotic drive.
16. A method according to any one of Claims 4 to 6 wherein a.c. power is applied to provide primary heating of the formation and d.c. potential is utilized as a superimposed bias for providing electro-osmotic drive.
17. A method according to Claim 7 wherein a.c.
power is applied to provide primary heating of the formation and d.c. potential is utilized as a superimposed bias for providing electro-osmotic drive.
power is applied to provide primary heating of the formation and d.c. potential is utilized as a superimposed bias for providing electro-osmotic drive.
18. A method according to any one of Claims 1 to 3 wherein said electrodes are disposed substantially horizontally in rows spaced substantially vertically from one another, with the electrodes nearer the top of the formation being at a more positive d.c. potential than the lower electrodes to assist gravity drainage.
19. A method according to any one of Claims 4 to 6 wherein said electrodes are disposed substantially horizontally in rows spaced substantially vertically from one another, with the electrodes nearer the top of the formation being at a more positive d.c. potential than the lower electrodes to assist gravity drainage.
20. A method according to Claim 7 wherein said electrodes are disposed substantially horizontally in rows spaced substantially vertically from one another, with the electrodes nearer the top of the formation being at a more positive d.c. potential than the lower electrodes to assist gravity drainage.
21. A method according to any one of Claims l to 3 wherein fluids are added to replace fluids produced by electro-osmosis.
22. A method according to any one of Claims 4 to 6 wherein fluids are added to replace fluids produced by electro-osmosis.
23. A method according to Claim 7 wherein fluids are added to replace fluids produced by electro-osmosis.
24. A method according to any one of Claims 1 to 3 wherein fluids containing surfactants are added at respective electrodes.
25. A method according to any one of Claims 4 to 6 wherein fluids containing surfactants are added at respective electrodes.
26. A method according to Claim 7 wherein fluids containing surfactants are added at respective electrodes.
27. A method according to any one of Claims 1 to 3 wherein fluids containing polymers are added at respective electrodes.
28. A method according to any one of Claims 4 to 6 wherein fluids containing polymers are added at respective electrodes.
29. A method according to Claim 7 wherein fluids containing polymers are added at respective electrodes.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48974683A | 1983-04-29 | 1983-04-29 | |
| US489,746 | 1983-04-29 | ||
| US603,583 | 1984-04-25 | ||
| US06/603,583 US4645004A (en) | 1983-04-29 | 1984-04-25 | Electro-osmotic production of hydrocarbons utilizing conduction heating of hydrocarbonaceous formations |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1221054A true CA1221054A (en) | 1987-04-28 |
Family
ID=27049814
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000452976A Expired CA1221054A (en) | 1983-04-29 | 1984-04-27 | Electro-osmotic production of hydrocarbons utilizing conduction heating of hydrocarbonaceous formations |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4645004A (en) |
| CA (1) | CA1221054A (en) |
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| US4957393A (en) * | 1988-04-14 | 1990-09-18 | Battelle Memorial Institute | In situ heating to detoxify organic-contaminated soils |
| EP0387846A1 (en) * | 1989-03-14 | 1990-09-19 | Uentech Corporation | Power sources for downhole electrical heating |
| US5065819A (en) * | 1990-03-09 | 1991-11-19 | Kai Technologies | Electromagnetic apparatus and method for in situ heating and recovery of organic and inorganic materials |
| US5152341A (en) * | 1990-03-09 | 1992-10-06 | Raymond S. Kasevich | Electromagnetic method and apparatus for the decontamination of hazardous material-containing volumes |
| WO1991015248A1 (en) * | 1990-03-30 | 1991-10-17 | Iit Research Institute | Method and apparatus for treating hazardous waste or other hydrocarbonaceous material |
| US5835866A (en) * | 1990-03-30 | 1998-11-10 | Iit Research Institute | Method for treating radioactive waste |
| US5664911A (en) * | 1991-05-03 | 1997-09-09 | Iit Research Institute | Method and apparatus for in situ decontamination of a site contaminated with a volatile material |
| US5914020A (en) * | 1994-12-05 | 1999-06-22 | E. I. Du Pont De Nemours And Company | Electric field method and apparatus for decontaminating soil |
| GB2301125B (en) * | 1995-05-25 | 1999-01-27 | Norske Stats Oljeselskap | Treatment of subsurface hydrocarbon reservoirs |
| RU2104393C1 (en) * | 1996-06-27 | 1998-02-10 | Александр Петрович Линецкий | Method for increasing degree of extracting oil, gas and other useful materials from ground, and for opening and control of deposits |
| US5829528A (en) * | 1997-03-31 | 1998-11-03 | Enhanced Energy, Inc. | Ignition suppression system for down hole antennas |
| US6199634B1 (en) | 1998-08-27 | 2001-03-13 | Viatchelav Ivanovich Selyakov | Method and apparatus for controlling the permeability of mineral bearing earth formations |
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| US7073578B2 (en) * | 2002-10-24 | 2006-07-11 | Shell Oil Company | Staged and/or patterned heating during in situ thermal processing of a hydrocarbon containing formation |
| US7091460B2 (en) * | 2004-03-15 | 2006-08-15 | Dwight Eric Kinzer | In situ processing of hydrocarbon-bearing formations with variable frequency automated capacitive radio frequency dielectric heating |
| ATE392536T1 (en) | 2004-04-23 | 2008-05-15 | Shell Int Research | PREVENTING SCABING EFFECTS IN DRILL HOLES |
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| DE102008044955A1 (en) * | 2008-08-29 | 2010-03-04 | Siemens Aktiengesellschaft | Method and apparatus for "in situ" production of bitumen or heavy oil |
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| CA2974712C (en) | 2017-07-27 | 2018-09-25 | Imperial Oil Resources Limited | Enhanced methods for recovering viscous hydrocarbons from a subterranean formation as a follow-up to thermal recovery processes |
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-
1984
- 1984-04-25 US US06/603,583 patent/US4645004A/en not_active Expired - Fee Related
- 1984-04-27 CA CA000452976A patent/CA1221054A/en not_active Expired
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