US2675081A - Method and apparatus for pumping and heating oil wells - Google Patents

Description

T. J. NOWAK April 13, 1954 METHOD AND APPARATUS FOR PUMPING AND HEATING OIL WELLS Filed Oct. 25, 1950 Illu) l .Ii .l1 |11 'Ill/lll will Patented Apr. 13, 1954 METHOD AND APPARATUS FUR PUMPING AND HEATING OIL WELLS Theodore J. Nowak, San Pedro, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application October 23, i956, Serial No. 191,575

This invention relates to a method and apparatus for heating oil wells whereby the rate of oil now and the net yieldof oil can be increased. More particularly, this invention relates to a method and apparatus for the combustion of busted within the welll bore. Such methods have generally met with Alittle` or no commercial suc,- cess partly due to the type'of apparatus employed andV poor heat `transfer obtained thereby and partly due to the fact that the hot oil is rapidly cooled during transitfrom the oil-bearing formation to the earth surface with the resultant deposition of wax and other materials. The wax and other deposits cause rapid plugging, fouling' of the rods, pumps and other elements.

A new method for heating wells has been discovered which combusts a minor portion of the oil by a submerged flame technique within the Well bore in close proximity to `the oil-bearing formation. The combustion gases are employed to transfer heat to the surrounding oil and assist in the pumping of the heated oil. The heated gases and oil are preferably also passed through a heat transfer zone, wherein a substantial portion of the heat generated' is transmitted'through I'.

radiation or convection to the surrounding oiloearing formation.

1t is an object oi this invention to heat an oilbearing formation and simultaneously recover oil from the oil-bearing formation whereina minor portion oi the oil production is combusted and the heated products from such combustion are passed through a heat transfer zone wherein a maior part of the heat generated thereby is transmitted to the oil-bearing formation.

It is another object of this invention to provide an apparatus for simultaneously pumping an oilbearingr formation and heating such oil-bearing 10 Claims. 4(Cl. 16B-17) formation, which apparatus employs a portion of v the oil flow as fuel therefor.

It is another object of this invention to decrease pumping costs in the production of waxy crude oil or other crudes which deposit gums or solids upon cooling;

It is another object of this invention to utilize a portion'of the oil production within a well bore in order to heat the oil-bearing formation and pump orassist in pumping such oil production from the oil pool at the bottom of the well.

It is another object of this invention to cornbust oil within an oil Well bore by a submerged combustion technique wherein a maximum transfer of heat from the combustion zone to the surrounding oil is effected and wherein the heated oil resulting therefrom is employed `to heat the oil-bearing formation.

Other objects of this invention will become apparent to those skilled in the art as the description thereof proceeds.

Briefly, this invention relates to a new method for heating oil-bearing formations 4and pumping the oil produced therefrom. The invention is in part based on a new submerged burner. Oxygen or other molecular oxygen-containing gas, with or without'preheating, is passed fromy the burner into a combustion zone which is surrounded by crude oil. A portion of the crude oil surrounding the combustion zone is drawn into contact with the oxygen and is combusted as a result thereof. The heat generated in the combustion zone is radiated or otherwise transmitted to the surrounding crude oil.

In a preferred modification of the invention the burner is located below the liquid level within the bore hole such that a continuous supply of crude oil may be drawn into contact with the combustion `zone and passed upwardly through a Venturi constriction and thence to the earths surface. A plurality of heat radiating varies surrounds the Venturi constriction to facilitate the transfer oi heat from the oil and gases carried therein to the surrounding media. In another modication of the invention a plurality of such burners may be employed in series with successive burners taking suction on the eluent oil from the preceding burner and Venturi yconstriction combination. In another modication of the invention a portion of the hot crude oil, after passage through the Venturi constriction, may be discharged through a suitable opening into the bore hole.

While the exact reasons for the increase of oil production upon heating are not known, it is quite possibly due to the decreased viscosity of the oil in the heated formation, the melting of wax deposits in the formation, the expansion of gas pockets in the formation during heating and the like.

Figure i shows `an elevation View` oi an oil well employing a plurality of burners in order to heat crude oil and the surrounding formation and also to provide energy for pumping the crude oil to the earth surface.

Figure 2 shows a partly sectional elevation View of the burner and Venturi constriction employed below the surface of the oil pool in Figure 1.

Figure 3 shows a cross-sectional view of Figure 2 taken through the plane 3 3.

Figure 4 shows a modification of the burner which is employed in Figure 1 above the surface of the oil pool.

Figure 5 shows a sectional elevation View of an alternative type burner which may be employed below the surface of an oil pool and wherein the -oxygen is supplied to the burner through a central coaxial pipe passing through the one or more Venturi constrictions and wherein part of or all of the heated oil may be recycled to the oil pool in contact with the formation.

Figure 6 shows a method for piping oxygencontaining gas through a plurality of burners by means of a central coaxial pipe.

Figure 7 shows a means for igniting a burner within the well bore.

Figure 8 shows a sectional elevation view of a conventional type pump which may be employed at any suitable distance in the tubing above the burner-pump of this invention.

Perhaps the method and apparatus of this invention can best be understood by reference to the drawings.

Referring now more particularly to Figure 1, oil well I I is drilled from earth surface I2 through various formations I3 into oil-bearing formation It. Casing I5 is tted with casing head i5 and passes downwardly through the well bore to within a short distance above oil-bearing formation i4. Casing I5 is fitted with a conventional gas outlet system indicated by pipe I'I.

Tubing I8 is tted with oil production line I9. Tubing IS passes downwardly through casing head I5 and through well I I to the bottom thereof. At the earths surface compressor takes suction on line 2I carrying oxygen-containing gas and forces such gas under pressure into oxygen f supply line 22 which passes downwardly through casing head I5 and into well I I.

The lower portion of tubing I8 is fitted with plug 23 for protection in case of fall. Above plug 23 is located burner housing 24 enclosing burner 25. Burner housing 24 is fitted with a series of ports 25 which permit the flow of oil from the external oil pool 2l' into contact with burner 25. Above burner housing 24 is located successively heat transfer unit 28, burner housing 29, heat transfer unit 35, coupling 3i, burner housing 32, heat transfer unit 3s and lconnecting tubing 34 which passes to the earths surface.

Heat generated by burner 25 is at least partially radiated by heat transfer unit 28 to the surrounding oil pool 2l which in turn heats the surrounding oil-bearing formation I4 by convection. The burner located within burner housing 29 and heatV transfer unit 3B are located above the liquid level of oil pool, 2l' and radiate heat from the het oi1 fiowing therethrough to the surround- `ing oil-bearing formation I4 through the intervening gaseous phase by means of radiation. The oil flow from the formation is increased as a result of the heating regardless of the method of transfer. More effective heat transfer to the formation is obtained by radiation through the gas phase, however.

At the earths surface electrical generator supplies a suitable current to ignite the various burners. The one terminal -of generator 35 is connected to insulated ignition rod 35 which passes downwardly through tubing head 31 and tubing I8. The lower tip 36 of ignition rod 35 is non-insulated and comprises an exposed electrically conductive surface. The other terminal of generator 35 is connected to tubing I8 through casing head I6 to which it is grounded. Ignition rod 35 is slideable through the several burner elements and when passed into the proximity of a burner can be momentarily charged by generating a current in generator 35 to produce a spark of electric arc in the vicinity of the burner in order to ignite the burner.

Referring now more particularly to Figure 2, which shows an enlarged cross-sectional portion of the burner and heat transfer unit assembly, air or other oxygen-containing gas is introduced through line 22 into burner 25 whence it passes into the combustion zone surrounding burner 25. Burner housing 24 is submerged in the oil pool 2'! and crude oil flows through the several ports 26 into contact with the combustion zone surrounding burner 25. A portion of such oil in contact with the combustion zone is continuously combusted in the ame to produce oxidation products which in turn transmit heat to the enveloping oil. The hot oil and gases flow upwardly through burner housing 24 and enter converging zone inlet 4I) whence they pass through constriction zone 4I and thence to diverging zone outlet 42. The inlet 4I) and outlet 42 of heat transfer unit 28 are surrounded by a plurality of heat transfer vanes 43 which transmit and radiate heat from the hot oil flowing within, through the chamber walls 44 to the surrounding media which may be either liquid or gaseous. The partially cooled oil leaving outlet 42 passes upwardly to a second burner housing 29 or other suitable coupling to thev well tubing.

While only a single burner and heat transfer unit of Figure-1 has been shown in detail, the remaining burners, burner housings, and heat transfer units are of substantially the same ccnstruction as has been shown in Figures 1 and 2 with the exception that plug 23 is replaced with a suitable nipple or other coupling. Where the burner housing is not located below the liquid level of the oil pool as in the case of burner housing 29 and burner housing 32 of Figure 1, no ports are provided for the inlet of oil. In certain cases small ports with or without attached ducts may be provided to discharge a portion of the hot oil from the tubing to the surrounding media in order to provide more eiiicient heat transfer to the surrounding media. In all such cases, however, the combustion zone of each of the burners is of the submerged type wherein a part of the oil or gas is burned beneath the oil surface so as to heat the oil simultaneously.

Referring more particularly to Figure 4, the oxygen containing gas may be introduced through line 5I) to a plurality of burners 5I and 52, respectively, which are suitably displaced to permit the coaxial passage of oxygen-containing lines, burner rods for igniting burners and the like. The burner housing 53 shown in Figure 4 has no ports for the entry of oil and may therefore be employed above the liquid level within well bore in those cases where it is not desired to recycle hot oil.

Referring more particularly to Figure 3, which is a cross-section of Figure 2 through the plane 3 3, the hot oil passes through the center con- Striction 4I. The walls 44 of the outlet 42 and 7 nby convection or by conduction in the oaseV of recycle oil. Furthermore, the combustion gases are not wasted but are employed to assist in pumping the oil and in maintaining such oil in a continual state of turbulence during its transport to the earth surface so as to minimize the normal deposition of wax which readily occurs under these circumstances.

Furthermore, this invention relates to a new type of subsurface burner and heat transfer system for use in oil wells which accomplish heating and pumping.

The method of use of the burners and heat transfer units of this invention depends primarily upon the desired result. Very often only a single burner and a single heat transfer section need be employed, particularly when the oil is readily pumpable, with only slight heating and when a conventional pump is to be employed in conjunction therewith. Where the production from the well is extremely low indications are that the well is very amenable to heat treatment and under these conditions a plurality of burners and heat transfer units are normally employed in proximity of the oil-bearing formation.

Where a plurality of units are employed, and

sometimes under other circumstances where but a single unit is employed, it is desirable that the heat transfer section be located above the liquid level of the oil pool and facing the exposed surface of the oil-bearing formation. Under these conditions there is obtained a maximum heat transfer from the heat transfer unit to the formation with a consequent maximum improvement in the iiow of oil from the formation.

A special feature of this invention lies in the fact that the combustion of the oil takes place within an envelope of oil which is simultaneously heated by .the combustion. In using the submerged heater the heat transfer from the flame to the formation is accomplished by a two-step process which may be arbitrarily designated as" 1) direct, and (2) indirect. The direct heat transfer process takes place where the heat of the ame, by virtue of its submergence, is transferred directly to the enveloping oil. In this step there are no hot gas-to-metal or metal-to-liquid interfaces such as are necessary in the conventional iiame heaters and accordingly the heater of this invention is not impaired by gas or liquid films, dirt, scale or other insulating barriers which might be deposited upon the burner surfaces. Thus the burner of this invention may be operated during long on-stream periods with a minimum of vmaintenance being required. Furthermore, the formation of hot spots due to corrosion or plugging within the metal tubes of the conventional heaters. is not a problem.

The heat absorbed Aby the'oil from theA submerged flame' is then transferred at least in part to the vanes surrounding the heat transfer section such as was shown in Figures l' and 2. The heat transferred through such vanes ultimately reaches the formation by radiation or convection. In this second part of the heat transfer, i. e. through the vanes, the problem of varying oil temperatures is not met and a maximum control of the heat transfer can be had.

The heat transfer unit of the apparatus provided by this invention preferably has a converging zone and a diverging zone of the Venturi type. Units of this type are well known and are described, for example, in Principles of Chemical Engineering vby Vilalker., Lewis, McAdamsA and Gilliland, i937 edition onpage 68 et seq. Pref- 8 l erably the converging zone has a total angle of about 25 and the diverging zone has a total angle of about 7.

The foregoing disclosure of this invention is not to be considered as limiting since many variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the following claims.

I claim:

1. In a method for increasing production from an oil well in which a well tubing communicates from the earth surface to a body of petroleum at the bottom of the well bore, the steps which comprise introducing a, stream of oxygen-containing gas directly into and below the surface of said body of petroleum and igniting the mixture of oxygen-containing gas and petroleum vapor which is thereby formed to produce a flame submerged in said body of petroleum, said stream of oxygen-containing gas being directed upwardly within said body of petroleum and towards the opening in said well tubing thereby causing said flameand the combustion products thereof to be directed upwardly and towards said opening in said well tubing.

2. The method of claim 1 wherein the oxygencontaining gas is air.

3. In a method for increasing production from an oil Well in which a well tubing communicates from the earth surface to a body of petroleum at the bottom of the well bore, the steps which comprise introducing a stream of oxygen-containing gas directly into and below the surface of said body of petroleum; igniting the mixture of oxygen-containing gas and petroleum vapor which is thereby formed to produce a flame submerged in said body of petroleum, said stream of oxygencontaining gas being directed upwardly within said body of petroleum and towards the opening in said well tubing thereby causing said flame and the combustion products thereof to be direoted upwardly and towards said opening in said well tubing and by their jet action to assist in raising non-combusted petroleum through said tubing; Awithdrawing said combustion products and non-combusted petroleum upwardly through said tubing, and transferring heat from said combustion products and non-combusted petroleum to the surrounding formation.

4. The method of claim 3 wherein the oxygencontaining gas is air.

-said body of petroleum.

6. The method of claim 3 wherein a portion of the non-'oombusted petroleum is returned to the body of petroleuin in the well boresubsequeni.`

to the transfer of heat therefrom.

7. A well heating apparatus comprising a combustion chamber having a fluid outlet in the upper surface thereof and at least one port adapted to permit the flow of liquid into said chamber when the latter is submerged in a body of said liquid, gas inlet means positioned within said chamber and directed towards the fluid outlet thereof, ignition means positioned within said chamber adjacent said gas inlet means, and heat transfer means having a uid outlet and a iiuid inlet, said heat transfer means being attached to said combustion chamber in such manner that the fluid inlet ofthe heat transfer means is in register with the iiuid outlet of the combustion chamber.

8. A well heating apparatus comprising a cylin drical combustion chamber having a closed lower surface, an open upper surface and a lateral surface provided with at least one port adapted to permit the flow of liquid into said chamber when the latter is submerged in a body of said liquid, gas inlet means positioned within said chamber and having a gas outlet directed towards the opening in the upper surface of said chamber, ignition means positioned within said chamber adjacent to said gas outlet, and tubular heat transfer means attached to said combustion chamber having a uid inlet in register with the opening in the upper surface of said combustion chamber and a fluid outlet adapted to being joined to a well tubing.

9. A well heating apparatus according to claim 8 wherein the tubular heat transfer means is of Venturi shape having exterior iins.

10. A well heating apparatus according to claim 8 and comprising means for withdrawing from the upper portion of the heat transfer means a portion of the uid passing through said heat transfer means.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,449,420 Kreager et al Mar. 27, 1923 1,473,348 Howard Nov. 6, 1923 1,554,444 Loomis Sept. 22, 1925 2.272,47? Pfleger Feb. 10, 1942 2,444,754 Steffen July 6, 1948 2,444,755 Steffen July 6, 1948 2,500,990 Higginbotham et al. Mar. 21, 1950 2,506,853 Berg et al. May 9, 1950

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