US3386508A - Process and system for the recovery of viscous oil - Google Patents

Description

June 4, 1968 w. J. BIELSTEIN ETAL 3,386,508

PROCESS AND SYSTEM FOR THE RECOVERY OF VISCOUS OIL Filed Feb. 21, 1966 2 Sheets-Sheet 1 SHALE SLOTTED CASING I I INVENT0R$ l m rum .LBIELSTEII, l BY mum mun,

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June 4, 1968 PROCESS AND SYSTEM FOR THE RECOVERY OF VISCOUS OIL Filed Feb. 21, 1966 W. J. BIELSTEIN ETAL INJECTION FLUlD $TE/AM & nor WATER- now SLOTTED sscnou 21 STEAM & HOT WATER FLOW 2 Sheets-Sheet 2 IIIIIIIIIIIIIIIIIHHI:

- INVENTORS,

.BIELSTEII, GJIHL,

United States Patent 3,386,508 PROCESS AND SYSTEM FOR THE RECOVERY OF VISCOUS OIL Walter J. Bielstein and Lawrence G. Raw], Houston, Tex., assignors to Esso Production Research Company Filed Feb. 21, 1966, Ser. No. 529,020 10 Claims. (Cl. 166-11) ABSTRACT OF THE DISCLOSURE A well bore is drilled into a subsurface formation containing viscous oil and then a plurality of wells is drilled to intersect the well bore and hot fluid is injected into the formation through the plurality of wells to cause viscous hydrocarbons to flow into the well bore.

The present invention is directed to recovery of viscous oil. More particularly, the invention is concerned with the recovery of viscous oils by the use of heat. In its more specific aspects, the invention is concerned with the recovery of viscous oils in which heated fluids are injected into a subsurface earth formation containing the viscous oils.

The present invention may be briefly described as a method of recovering viscous hydrocarbons from a subsu-rfiace earth formation containing the viscous hydrocarbons in which a well bore is drilled at least into the subsurface earth formation containing the viscous hydrocarbons. This well bore may be relatively large and may have a diameter ranging from about 1 to about 10 feet. Preferably, it will have a diameter in the range from about 2 to about 5 feet. The well bore may be drilled to provide a sump in which the viscous oil may accumulate. A plurality of wells is then drilled to intersect the well bore in the subsurface formation at a point preferably above the bottom of the well .bore. The well bore and the plurality of wells communicate fluidly with the subsurface formation. A heated fluid which may be air, steam, hot water, combustion products or the like may be injected into the formation from the plurality of wells. Injection of the heated fluid causes heating of the subsurface formation and, therefore, causes the viscosity of the viscous hydrocarbons to be reduced to the extent that the viscous hydrocarbons flow into and accumulate in the well bore. The heated viscous hydrocarbons may flow through the formation to the well bore and/or into the plurality of wells and thence into the well bore. Ordinarily, both flows may occur. Thereafter, the viscous hydrocarbons may be removed from the well bore such as by pumping.

The temperature of the heated fluid, whether it be steam, hot water, air or combustion products, should be sufficient to heat the formation and to cause the viscous hydrocarbons to flow. A suitable temperature of the heated fluids may range from about 150 F. to about 650 F.

In the practice of the present invention, it is contemplated that the well bore Will be of relatively large diameter such as a diameter in the range of about 1 to about feet. A well bore ranging in diameter from about 2 to about 5 feet may be satisfactory. Likewise, in accordance with the present invention, the well bore should be drilled into the formation a suflicient distance "ice to provide a sump in which the viscous hydrocarbons accumulate. Thus, the well bore may be drilled completely through the subsurface formation containing the viscous hydrocarbons to provide a sump for the viscous hydrocarbons. The well bore may or may not be cased or lined with pipe.

Conversely, the wells Which intersect the Well bore should intersect the well bore at a point above the bottom of the well bore such that a Sump is provided for accumulation of viscous hydrocarbons in the well bore.

In accordance with the present invention, it is contemplated that the heated fluid will be injected selectively from the plurality of wells into the subsurface formation to cause heating of same and reduction of viscosity of the viscous hydrocarbons. Preferably, the heated fluid is injected selectively near the top of the viscous hydrocarbon-containing subsurface earth formation, but it is within the contemplation of the present invention that the heated fluid may be injected at any selected point in the subsurface formation. This may be accomplished by providing a vertically movable valved injector pipe or tubing in each of the Wells. The pipe is valved at its lower end and is also provided with a packer means just above the valve. A section of the pipe is slotted or perforated above the packer to allow fluid communication between the interior and exterior of the pipe. The valve means may be opened by response to certain temperatures or pressures. As the pipe is moved downwardly in the Well, the packer and closed valve control the area of fluid injection into the formation.

Another means of injecting the heated fluid at a selected point is to provide a valved pipe similar to that mentioned above with the added provision of two packers spaced apart, above and below the perforated or slotted section. In either case, all or part of the heated fluids may be pumped into the formation or through the well bore to the recovery well.

The present invention also involves a system for recovery of viscous hydrocarbons from a subsurface earth formation containing the viscous hydrocarbons which involves a well bore penetrating the subsurface formation having openings or perforations into the subsurface formation. A plurality of wells intersect the well bore in the subsurface formation and extend laterally through the subsurface formation, each of the plurality of wells having openings or perforations into the subsurface formation. Means are provided in each of the plurality of wells for injecting a heated fluid from the wells at least at a selected point into the subsurface earth formation. Means are provided in the Well bore for recovering viscous hydro-carbons which flow into and accumulate in the well bore. Such means may include a pumping or other lifting means. The present invention is quite advantageous and useful in that it allows substantially complete recovery of viscous hydrocarbons from subsurface earth formations which heretofore has been accomplished only with difficulty.

The present invention will be further illustrated by reference to the drawing in which:

FIGURE 1 is a sectional view of a system in which the present invention may be employed;

FIGURE 2 is a top view looking down on an arrangement of wells in accordane with the present invention;

FIGURE 3 is an enlarged fragmentary view of a por- 3 'tion of FIGURE 1 illustrating fluid action or flow during operation of the present invention; and

FIGURE 4 is a view partly in section illustrating a modification of the device of FIGURE 3.

Referring now to the drawing and particularly to FIG- URES 1 and 2, numeral 11 designates the earths surface from which a well bore 12 has been drilled by well known means to penetrate a subsurface earth formation 13 and to extend therethrough into an impervious formation 14. Also drilled into the subsurface earth formation 13 which contains viscous oil is a plurality of wells 15, 16, 17 and 18 which are drilled through the formation 13 and intersect the well bore 12. Extending from the earths surface into the well bore 12 is a tubing string 19 carrying a pump means 20 or other oil lifting means which is arranged adjacent the bottom of the well bore 12. Each of the wells 15, 16, 17 and 18 is provided, respectively, with casings 21, 22, 23 and 24.

The section of the well bore 12 below the casing 25 is suitably a slotted liner 26. Similarly, the sections of the casings 21, 22, 23 and 24 in the subsurface earth formation 13 may be slotted liners 27, 28, 29 and 30. Such slotted liners are well known.

The arrangement of the well bore 12 and the wells such as and 16 is shown in FIGURE 2 as a top view. Although only four injection wells are shown in FIGURE 1, it will be evident from FIGURE 2 that any desired number of wells may be drilled about the recovery well 12 to adequately blanket the desired area of recovery.

Each of the well casings 21-24 have positioned therein an injector pipe or tubing 31 which is movable vertically within the casing such as 21, illustrated in FIGURE 3. Tubing 31 has valve means 32 positioned at its lower end and also a packer means 33 just above the valve means. The section of tubing just above the packer 33 is provided with slots or perforations 34. The upper end of tubing 31 passes through a pack-off wellhead 35 (see FIGURE 1) and is valved at its upper end and also connected to a source of heated fluid. The wellhead 35 is also provided with a valved conduit 36 which is also connected to the source of fluid. The conduit 36 fluidly connects with the annulus between the casing and tubing. The valves are operably responsive (for opening and closing) to specific temperatures or pressures.

Referring now to FIGURE 4, it will be seen that the tubing such as 31A has been modified to provide two packer means such as 33 and 33A which are positioned, respectively, below and above the perforations 34 to afford a straddle pack effect. The tubing 31A is also provided with the valve means 32 at its lower end below packer means 33.

The present invention operates as follows. It will be assumed that the wells 12-18 have been drilled as in dicated and the tubing strings 19 and located as shown. A heated fluid such as air, steam or hot water, or flue gases at a temperature in the range indicated is then introduced into the formation surrounding the slotted sections of the wells 15, 16, 17 and 18. The tubing during this injection operation may be moved up and down in the casing with the valve 32 open or closed depending on the operation. Fluid such as steam may be introduced through the tubing and tubing-casing annulus A for the purpose of maintaining the heat in the formation adjacent the perforated liner. Until a large amount of heat has been dissipated into the formation, steam will need to be cycled through the injected well bores.

As the formation surrounding the slotted section, such as 27 shown in FIGURE 3, is heated, the viscosity of the oil is reduced to a point such that it flows into the well bore below the packer 33 and, hence, into the recovery well 12 and forms a body of oil 40 which may be then lifted to the surface by means of the pump 20 and tubing string 19. Although much of the lowered viscosity oil fiows through the various drain Wells to the recovery well, it

is evident that part of the oil may flow directly from the formation into the sump of the recovery well 12.

As the formation surrounding the slotted section, such tion is indicated by the short, arrowed lines while steam and hot water flow is indicated by the long curved arrowed lines. The flow of oil and water into the recovery well 12 is indicated by the heavy arrowed lines.

While it may be preferred to introduce the hot or heated fluid into the formation 13 adjacent the top thereof as shown in FIGURE 3, it is within the contemplation of the present invention to introduce the hot fluid selectively into any portion of the formation 13. Thus, at the beginning of the operation, it may be desirable to introduce the hot fluid near the top of the formation 13 and thereafter selectively and/or progressively introduce the hot fluid at lower points in the formation. This may be accomplished also by moving a tubing string such as 31 carrying a valve, such as 32, and packer 33 down any of the wells 15, 16, 17 or 18 and causing same to open by pressure differential, specific temperature, or by manipulation by wire lines from the surface as may be desired. For specific spotting of injection fluids into the formation, it is evident that the straddle packers of FIG- URE 4 would be more desirable.

The techniques for drilling large shafts ranging in diameter from 1 to 10 feet are well known and, therefore, will not be described further herein. Likewise, the techniques for drilling directional wells are well known and need not be described further.

As examples of types of viscous oil which may be recovered in accordance with the present invention, there are oil fields in California, Kansas and Texas, and elsewhere in the world which are susceptible to treatment in accordance with the present invention and recovery of hydrocarbons therefrom. Thus, the present invention is quite important and useful and also advantageous.

Ths nature and objects of the present invention having been completely described and illustrated, and the best mode and embodiment contemplated set forth, what we wish to claim as new and useful and secure by Letters Patent is:

1. A method of recovering viscous oil from a subsurface formation containing said viscous oil which comprises:

drilling a well bore at least into said subsurfaces formation;

drilling a plurality of wells to intersect said well bore in said subsurface formation;

said well bore and said plurality of wells communicating fluidly with said subsurface formation; injecting a heated fluid into said formation from said plurality of wells;

thereby causing said viscous oil to flow into and accumulate in said well bore; and

recovering said viscous oil from said well bore.

2. A method in accordance with claim 1 in which the heated fluid is steam.

3. A method in accordance with claim 1 .in which the heated fluid is hot water at a temperature sufiiciently above formation temperature to cause said viscous oil to flow.

4. A method in accordance with claim 1 in which the heated fluid is a gas.

5. A method in accordance with claim 1 in which the well bore is of a diameter substantially greater than the diameter of each of said plurality of wells and said well bore extends below the point where said Wells intersect the well bore.

6. A method in accordance with claim 1 in which heated fluid is injected selectively from said plurality of wells at a point adjacent the top of said subsurface formation.

7. A method in accordance with claim 1 in which said viscous oil is recovered from said well bore by pumping.

8. A method in accordance with claim 1 in which the plurality of wells is directionally drilled from horizontally spaced-apart points on the earths surface from said well 5 bore through said subsurface formation to expose a large area of each of said plurality of wells to said subsurface formation.

9. A method in accordance with claim 1 in which the heated fluid is injected into said subsurface formation from selected points in said plurality of wells.

10. A system for recovery of viscous oil from a subsurface earth formation containing viscous oil which comprises:

a well bore penetrating said subsurface formation having openings into said subsurface formation;

a plurality of wells intersecting said well bore in said subsurface formation extending laterally through and having openings into said subsurface formation;

means in said wells for injecting a heated fluid from said wells at least at a selected point into said subsurface formation; and

means adjacent the bottom of said well bore for recovering viscous oil which flow into and accumulate in said well bore.

References Cited UNITED STATES PATENTS Pevere et a1 166-11 Hennig 166-11 Tek et al 166-11 Woodruff 16611 X Rogers et al. 166-11 Cryer 16652 Hamilton et al 16611 X Thompson et al. 166-41 Dougan 16611 STEPHEN I. NOVOSAD, Primary Examiner.

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