US2974937A - Petroleum recovery from carbonaceous formations - Google Patents

Description

March 14, 1961 o. M. KIEL 2,974,937

PETROLEUM RECOVERY FROM CARBONACEOUS FORMATIONS Filed NOV. 5, 1958 PRODUCED S OIL SHALE HOT GASESVK INJECTED Orhor M. Kiel lnveniop By M Q. Attorney United States Patent O PETROLEUM RECOVERY FROM CARBONACEOUS FORMATIONS Othar M. Kiel, Tulsa, Okla., assignor to Jersey Production Research Company, a corporation of Delaware Filed Nov. 3, 1958, Ser. No. 771,435

2 Claims. c1. 262-3) This invention relates to a method for recovering petroleum oil from earthen formations containing hydrocarbons. The invention is specifically adapted to the production of petroleum from subterranean formations of low permeability and those formations in which the petroleum oil is closely bound to the formation material.

Large reserves of crude oil in the form of shale oil are potentially available in large deposits in both this country and abroad. Present methods of recovering this oil have rendered shale oil as a source of additional oil completely infeasible from the present economic viewpoint. It is known in the art that the conventional methods of obtaining petroleum oil from oil shale usually involve the minfrom such retorts then must be disposed of. Even though potential recovery of the oil may approximate 25-75 gallons per ton of shale processed, the aggregate m-imng and processing costs impose such aneconomic burden that shale oil is not at present a commercially feasible source of supply for petroleum.

Accordingly, it is an objective of the present invention to provide an oil recovery method wherein crude oil is readily recovered from oil bearing sub-strata. More specifically, this invention is a process for the in situ dissooiation of petroleum oil within oil shale deposits whereby the petroleum is readily removed and high recovery of oil in place is obtained. It is especially an object of the invention to provide a method for petroleum recovery which is rapid and efiicient. These and related objects of this invention will become more apparent from the ensumg description.

In the operation according to this invention, petroleum oil is separated from oil-bearing shale so that its recovery is readily realized. The first step in the process lies in providing a direct application of heat to an exposed surface of virgin strata. The heat and the application thereof are always applied directly to the surface of untreated strata. Treated strata or an oil-bearing formation is caused to disintegrate and fall away from the untreated oil-bearing formation. That is, the process may be called a selfstoping process which leaves a continuous face of virgin oil shale available for the application of heat to extract the oil therefrom. More particularly, the invention accomplishes in situ decomposition of the oil shale and induces the separation of the oil from the strata in a manner which permits the oil to be produced by a practical thermal activated oil recovery method.

In the process 'of this invention, oil shaleis heated in situ at a temperature above 600 F. and generally withr I expansion of the oil and its dissociation from the stratum the stratum to disintegrate. Thus the earthen 2,974,937. Patented Mar. 14, 1961 ICC 2 material contained in the stratum will separate and fall away from the oil-bearing formation. This leaves a fresh oil-bearing surface exposed to the hot gases.- 7

The process of this invention may be controlled in various ways. In general, the rate of injection of the hot gases may be readily adjusted and controlled by simply regulating the flow and temperature of hot gases onto the face of the shale deposit containing oil. High volumes of high temperature gases will tend to accelerate the rate of production; and, conversely, low volumes and temperatures will tend to retard the process.

In carrying out the present process, drifts or tunnels are made into an oil-containing shale wherein conduits 'or tubing containing perforations are placed along the base of an oil stratum. Well bores laterally spaced from an entrance of the drifts are also drilled as necessary. Tubing which has been placed along the base of the oil shale terminates at these well bores, with oil being produced through these boreholes. Tubing or pipes which are placed along the base of the oil strata are perforated along their lengths to disperse the hot gases onto the face of an oil shale. Further, drifts through which this perforated pipe or tubing is placed are made of sufficient size so that as the oil in the roof is extracted, the roof will stope or fall into the drift, exposing new formations t be treated. The invention may be better understood by reference to the attached figures which schematically depict the em-. bodiment of the invention contemplated to illustrate the best mode of carrying out the invention. a

Figure 1 illustrates a vertical crosssection through an oil-bearing stratum; and

iF-lglllB 2 illustrates avertical cross-section across Figure 1 along the lines I I'II and'further depicts steps in installation of the apparatus and operation of 'this'oilproducing process.

With reference to the drawings, especially to Figure 1,

the numeral 1' designates an oil-bearing formation above which is a relatively non oil-bearing impervious shale stratum 2 and below which is another relatively impervious stratum 3. Further, this deposit is shown outcrop material in a conventional manner. The casing placed in.

this manner leaves a borehole within the oil stratum which is completely uncased and will allow unrestricted flow of vapor from theupper part of the drift into the borehole.

As in conventional oil field practice, the casing may also be extended through the oil-bearing formation and, after being sealed in place, perforated by conventional means whereby produced fluid will pass through the perforations into the borehole to be produced to the surface. By using this technique of placing the casing and then per forating the casing at desired points, control of the production points for fluids from the formation may be effected.

As beforementioned, drifts or tunnels 12 are made into the oil-bearing stratum 1. These tunnels are directed to terminate at the well bore 10. Tubing 11 is then placed in the tunnel, the tubing containing perforations 14 and a pipe cap 16. A cap 15-which fits snugly around tubing 11is placed against the outcropping face of strata 1 and 3. Although not shown, cap 15 may be made of a size to extend over the outcropping face of the shale to seal on both formations 2 and 3 as well as caps of laterally spaced drifts preventing escape of gases therefrom. In the usual 3 case such a large cap is not necessary as oil shale is essentially impermeable to flow of fluids.

To better describe installation of the equipment and the operation of the process in this invention, attention is now directed to Figure 2. First referring to the portion of the figure above letter A, it can be seen that the producing well has been drilled to the top of stratum 3. A drift or tunnel 12 has been completed to the base of this production well 10. Now referring to the figure above the letter B, it can be seen that perforated tubing 11 has been placed in the tunnel 12. Thence looking at the drawing above the letter C, hot gases are being injected through tubing 11. Stoping or disintegration of the shale has started. The stoped shale is shown in the bottom of the drift 12 and is designated by numeral 20. Then on this same figure the illustration above the letter D shows the tunnel or drift 12 becoming larger, and more stoped formation material 20 gathering in this drift. Although material 20 is not shown in Figure 2 to cover tubing 11, it will do so except for perforations 14.

The 'stoped material falling from the roofs of the tunnels or drifts serves as direction batfies for the hot gases. That is, the stoped material falls around the upwardly directed hot gas jets which are injected from the perfora- "tions in the pipe. This stoped material will cover the tubing 11 between perforations 14 but not the perforations themselves, as the force of the upwardly directed hot gases will direct material 28 away from the perforations. There is adequate space for the spent shale in the drifts without covering perforations 14, since for each volume of oil shale that is treated 15 to 50 percent of shale oil will be removed leaving from 85 to 50 percent spent shale. These percentages correspond to the recoveries of oil from oil shale described earlier. The spent shale falling around perforations 14 will form baffles to direct the hot gases upward. These stoped material battles thus direct the hot gases onto the face of the shale and -.prevent the hot gas bypassing from the perforations of the pipe directly through the drift to a production well.

As'may be noted, the surface equipment which would normally be employed for producing and injecting the hot gases as well as the separation equipment for separating the injected gas from the produced oil vapors are not shown. Such equipment would be conventional, and its inclusion here is not considered essential for the purposes of this description.

The underground or in-place separation of the earthen material from the oil as carried out in accordance with the instant process reduces the large mining, crushing, and retorting costs involved in the methods presently used at the earths surface.

While the foregoing description has been directed toward an embodiment of the invention which is considered to constitute the best mode of carrying out the invention, it will be recognized that numerous modifications, additions, and subtractions may be made to the illustrated embodiment without departing from the spirit or scope of this invention.

The invention claimed is:

l. A method for producing oil from a stratum of oil shale comprising driving a drift along the lower portion of the stratum and placing a perforated conduit therein which is capped at its inner end, said drift terminating at a substantially vertical hole drilled from the ground surface, passing hot gases through the conduit toward said borehole at a temperature above 600 F. to vaporize at least a portion of the oil within the shale whereby stoping of the stratum occurs, and recovering oil from said borehole.

2. A method for producing oil from oil-bearing shale formation which :comprises driving a drift at the base of a formation and placing a perforated conduit therein, said drift terminating at a substantially vertical borehole drilled from the ground surface, passing hot gases at a temperature above 600 F. through the perforated conduit to the face of the oil-bearing shale so as to vaporize oil from said shale whereby said shale will stope into the drift leaving virgin oil-bearing shale continuously eX- posed to the hotgases, and producing oil fromv said borehole.

References (Jited in the file of this patent UNITED STATES PATENTS 2,813,583 Marx et al Nov. 19, 1957 2,876,838 Williams Mar. 10, 1959 FOREIGN PATENTS 164,551 Australia Aug. 11, 1955

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