US3242989A

US3242989A - Apparatus for the extraction of underground bituminous deposits

Info

Publication number: US3242989A
Application number: US215494A
Authority: US
Inventors: Schlicht Erika Marie; Lange Hans
Original assignee: Deutsche Erdoel AG
Current assignee: Wintershall Dea Deutschland AG
Priority date: 1961-08-08
Filing date: 1962-08-06
Publication date: 1966-03-29
Anticipated expiration: 1983-03-29
Also published as: DE1190418B

Description

March 29, 1966 s. scHLlcHT ETAL 3,242,989

APPARATUS FOR THE EXTRACTION OF UNDERGROUND BITUMINOUS DEPOSITS Filed Aug. 6, 1962 2 Sheets-Sheet l GUN THE/2 SCHL/CH T HANS LANGE ATTORNEYS March 29, 1966 G. scHLlcHT ETAL 3,242,989

APPARATUS FOR THE EXTRACTION OF UNDERGROUND BITUMINOUS DEPOSITS 2 Sheets-Sheet 2 Filed Aug. 6, 1962 /N VENTORS F1a/o f E m m .N m me m W G 5N JA R Em. W ms MM GH United States Patent O 3,242,989 APPARATUS FOR THE EXTRACTION OF UNDER- GROUND BITUMINOUS DEPOSITS Gnther Schlicht, deceased, late of Hamburg-Othmarschen, Germany, by Erika Marie Schlicht, legal representative, Hamburg-Gthmarschen, Germany, and Hans Lange, Wietze, Kreis Celle, Germany, assignors to Deutsche Ertil-Aktiengesellschaft, Hamburg, Germany Filed Aug. 6, 1962, Ser. No. 215,494 Claims priority, application Germany, Aug. 8, 1961, Sch 30,105 4 Claims. (Cl. 166-52) The present invention relates to the extraction of highly Viscous or solidified bitumens from underground deposits, more particularly, to a process and apparatus for the extraction of such bitumens through the application of heat.

Highly viscous or solid underground bituminous deposits have been extracted both by mining methods and by various processes involving the application of heat including gasification and dry distillation. The necessary heat for the extraction of such deposits can be introduced into the deposit in sufficient quantities only if a circulation of the heating medium through the deposit can be achieved. The greatest diiculty in obtaining such a circulation in a deposit consists of initially establishing a suicient permeability in the deposit for the circulation of a liquid heating medium. It is not possible to carry out any of these extraction processes requiring the application of heat by relying solely upon the conduction of heat through the deposit in order to transfer sutcient quantities of heat into the deposit. The temperature decreases so rapidly in the direction of the heat flow that such a heat transfer is a Wholly unfeasible operation.

The extraction of low-viscosity bitumens presents relatively little problem but the difficulties increase as the viscosity of the bitumens increases. One proposed solution has been to increase the pressure of the liquid heating medium. Even when the highest possible pressure is applied over an extended period of time to such a bituminous deposit, a limit is soon reached at which it is no longer possible to cause a highly viscous or solidied bitumen to flow.

Various processes have been devised for treating such highly viscous or solidified bituminous deposits wherein some degree of permeability of the deposits were obtained. Such processes include the various fracture processes which can be employed in many different variations and which essentially consist of discharging a fluid under pressure from a bore into the deposit which pressure is higher than the pressure at which the deposit begins to break up.

In the fracture processes, liquids containing sands are employed for making passages in the deposits. The sand is for the purpose of keeping these passages open in the vicinity of the bore so as to enable the liquids to pass therethrough. Only after these preparatory processes have been carried out can the bitumens be extracted by the introduction of heat or by combustion thereof in situ. However, ditiiculties may arise when part of the bituminous deposit becomes plastic and llows to close the previously formed passages. The continuation of the in situ process is thus rendered virtually impossible when almost all of the porous spaces and passages in the deposit are iilled with the plastic bitumen.

It is therefore the principal object of the present inven tion to provide a novel and improved process and apparatus for exploiting underground deposits of highly viscous or solidified bitumens.

In the present invention an apparatus is disclosed which essentially comprises a bore drilled into the ground to an underground bituminous deposit and having three concentric tubular casings therein. The outer casing is provided with a plurality of passages in the Wall thereof, spaced at different heights along the casing. A source of heat energy is installed in the bottom of the bore. A pump is mounted abovegroundand has supply and return lines connected to the several tubular casings for the circulation of a uidheating medium down through the bore, outwardly into the deposit, and then returning to.

the bore through the openings in the outer casing.

A second bore is provided spaced from the tirst bore.

and similarly comprises a plurality of concentric tubular -casings and is connected to the same aboveground pump. However, the second bore is not provided with a source of heat energy and the accessory equipment for such a source.

In carrying out the process of the present invention, a.

liquid heating medium is pumped downwardly through a central casing into heat-exchange relationship with the heat source positioned at the bottom of the bore. The heated liquid is then discharged outwardly of the bore at the bottom thereof and ows upwardly through a porous layer immediately adjacent the lower portion of the outer surface of the outer casing of the tube. The heating medium then returns into the bore through a passage in.

the outer casing and ows upwardly to the aboveground pump to be recirculated again through the bore.y

As the heating medium flows upwardly through the porous layer adjacent the casing, heat is transferred to the surrounding portions of the bituminous deposit.

Continued heating of the deposit reduces the heated portions of the deposit to a flowable state. Accordingly, the heating medium is circulated in increasingly longer flow paths at greater distances from the bore to continue to heat unheated portions of the deposit and reduce them to a flowable state.

In order to increase the ow path of the heating medium through the deposit, the heating medium is returned to the bore at progressively higher points along the outer casing.

After a sufficient quantity of the bituminous deposit hasn been rendered owable, water is then introduced through the casing of the bore and carries the bitumens upwardly through the bore to a processing plant where the bitumens are Separated from the Water according to knownand` conventional procedures.

Other objects and advantages of the present invention will be apparent upon reference to the accompanying drawing wherein:

FIGURE l is a diagrammatic view of the apparatus showing two bores drilled in an underground deposit in accordance with the present invention, and showing also flow paths of the heating medium through the deposit;

FIGURE 2 is a diagrammatic view partially in cross,

section of one of the wells having the nuclear reactor;

FIGURE 3 is a cross-sectional view along the line III- III of FIGURE 2;

FIGURE 4 is a cross-sectional view along the line 1V-` Ix-Ix of FIGURE s; and

FIGURE l0 is a cross-sectional view along the line X-X of FIGURE 8. v

With reference to the drawing` FIGURE 1 shows the arrangement of the present invention comprising boreholes 3 I'and -II which are drilled downwardly through the earth from the surface indicated as 1 into .an underground deposit 2 of a highly viscous or solidified bitumen.

Borehole I comprises an outer casing 3 within which there are arranged concentrically and coaxially therewith, a center casing 4 and an inner casing 5. The upper portion of the casing 3 is secured in the ground by cementing at 45 to a subsurface layer of rock. The lower portion of the outer face of the outer casing 3 is covered with a permeable metallic vcoating 7. This permeable coating 7 extend-s for a distance of about one third of the vertical height of the underground deposit 2.

The outer surface of the casing 3 is provided with a plurality of

apertures

8, 9, and 10 to which are connected passages which are curved upwardly as shown in the drawing. These passages are located in the space between the outerf casing 3 and the center casing 4.' These openingsY 8, 9, and .10 are at different heights along the outer casing and are also staggeredly positioned with respect to each other.

Rotary Values

11, 12, and 13 shown in FIGURES 3, 4 and respectively are provided for selectively closing the passages 8, 9, and respectively. These valves are xedly connected to the center casing 4 which is rotatably mounted within the bore. Thus, by rotating of the center casing 4 through pre-determined angles, the passages in the outer casing at different levels may be opened and closed in sequence.

L In that portion of the outer casing 3 which is covered by the permeable coating 7, FIGURE 6 there is provided an additional opening 14 having a passage connected thereto and similarly opened and closed by -a rotary valve 15 which is alsolconnected to the rotatable center casing 4.

The source of energy for the bore comprises a nuclear reactor 16, such as a boiling-water reactor, rotatably connected to the center casing 4 by a connection 17. The nuclear reactor 16 is provided with an expansible shield 18 which is expanded outwardly as shown at 19 when the nuclear reactor is in operation. A neutron-reflecting substance, such .as ordinary water, is positioned in the space between the shield 18 and the nuclear reactor 16.

' For the heating of the deposit a fluid heating medium, such -as the oil obtained from the deposit, is supplied by an aboveground pump 21 through supply conduits 22 to the upper end of the center casing 4 through a connection 2-3 which is Stationary but permits rotation of the casing 4. The Huid medium is returned from the bore through return lines 24, which connect the outer casing 3 with an intermediate reservoir 25, which in turn is connected to the pump 21 at 26. e

The process of the present invention is carried out in the following manner:

A heating medium, such as oil from the deposit, liquid hydrocarbon or a mixture of benzene and kerosene, is pumped under pressure into the bore through supply line 22 and passes downwardly through the bore in the space between the center casingl 4 and the inner casing 5. The liquid medium then passes in heat-exchange relationship with the nuclear reactor 16 and is discharged from the bottom of the center casing 4 into the deposit 2. The greater the paraffin constituents having a high melting point (70 C.) in the deposit, the higher must be the temperature' of the heating medium.

At the beginning of the process, the deposit is relatively solid and the liquid heating medium then ows upwardly along the outer surface of the outer casing 3 through the permeable layer 7. The liquid medium then enters the aperture 10 into the space between the outer casing 3 and the center casing 4 and is returned through return line 24 and reservoir 25 to the pump 21 to be recirculated through the bore.

As the heated oil ows upwardly through the permeable layer 7, heat is transferred by conduction to the adjacent layer of' the deposit. The continued transfer of the heat will render this portion of the deposit permeable and 'eventually tlowable. As the bitumen becomes less viscous and is susceptible to ow, it is removed by the circulating heating medium. As soon as this heated portion of the deposit is removed, the heated oil comes in contact with the next adjacent layer of the deposit, which is relatively cold, and heat is again transferred from th-e heated oil to this relatively cold layer of a bitumen. Thus, short heat transmission paths lare formed extending into the bituminous deposit and away from that layer of the deposit whichis contacted by the heated oil, which is at a relatively high temperature. The process is characterized by heat transfer into the bituminous deposit, both by the direct contact of the heated oil with the bituminous deposit and the conduction of heat for relatively short distances into the bituminous deposit from the contacted surface thereof. The heated oil remains in close contact with the bituminous deposit because of the continuous melting of the deposit and the removal of the same by the owing oil.

As the heated oil begins to flow at a distance away from the bore, a path is followed according to the arrows 27a. As the heating process continues, the paths of the flow of the heating .medium progress outwardly to 27h and 27C. At the same time, as the path ofthe heating medium becomes greater, the opening 10 is closed and the opening 9 is opened by the rotation of the center casing 4 through a suticient distance to actuate the respective valves. The latter phenomenon occurs because the

rotatable valves

11, 12, 13 and 15 on the middle casing 4 are offset relative to one another in such a manner that only one of the passageways through the outer casing 3 will be open at any one time. If, therefore, at the time for the delivery of the heating medium to commence, said medium will flow through opening 10, and then

openings

8, 9 and 14 will be automatically closed.

In order to improve the eiciency of the process, the

passages

9 and 10 are closed and the passage 14 is open. Through the passage 14, a highly viscous liquid, whose viscosity is not changed when heated, is forced under pressure into the deposit in the directions as indicated at 28. Such liquids include mixtures of water and carboxymethyl cellulose having a viscosity of 50-2000 centipoises, solutions containing 0.2-2% of carboxymethyl cellulose, or calcium aluminum silicate with water. The injection of this liquid into the deposit hastens the achievement of the permeability of the deposit further out from the bore. During the introduction of the highly viscous liquid through conduit 3 and through opening 14, al-l other openings, namely 10, 9 and 8 are closed, because by rotating conduit 4 through a predetermined angle only' one pair of openings wil-l come into registration at any one time while the others will remain closed. The circulation of the heating medium is, therefore, interrupted during the injection of the highly viscous liquid. After this introduction of the liquid has been completed, the center casing 4 is again rotated to close the passage 14 and the

passages

9 and 10 may be open to continue the circulation of the heating medium.

I When a nuclear reactor is employed as a heating source in borehole I and has a sufficiently high capacity, the same reactor can be used for supplying a heating medium for circulation to a second similar borehole. As seen in the drawing, borehole II is provided spaced from borehole I and is similar in all respects except for the nuclear reactor and its auxiliary structures. The corresponding components lof borehole II are indicated with the same reference numerals as the components of borehole I except with the addition of A.

Under particular circumstances it may be desired that. the oil supply to supply Iline 22A to the center casing 4A should be further heated prior to being introduced into the deposit. The circulation of the oil in this event can be obtained in the following manner:

The heated oil, resulting from its passage in heatexchange relationship with the reactor 16, is still subject to the high pressure of supply pump 21. A portion f the oil discharged at the bottom of central casing 4 is introduced into the bottom of the inner casing through distributors 29. This oil then Hows upwardly through inner casing 5 and is discharged at 30 into a connection which introduces the heated oil into the inner casing 5A at 31. This oi-l then ows downwardly through inner casing 5A and is discharged as shown at 32 into the deposit. This discharge 32 is in front of the flow of oil pumped into the central casing 4A and discharged therefrom at 33.

As an alternative construction, the heated oil may be supplied from inner casing 5 into the reservoir 25 from which it is supplied to the pump 21 and introduced into borehole II through supply line 22A.

As the process employing the two boreholes continues, increasingly wider areas of the deposit are heated until the zones of the deposit heated by the individual boreholes contact each other at 34. At this point, the deposit is permeable between the two boreholes. Continued application of the process will heat portions of the deposit above the contact point 34 and between the bores. Various known heat calculations can be carried through to determine to what extent the deposit will be heated.

When suicient portions of the deposit have been heated as described above and the bitumens contained therein have been rendered liquid or at least owable, the bitumens can then be extracted from the deposit. This is carried out by introducing ushing water through the

inner casings

5 and 5A through the distributors 29 and 29A into the lower portion of the deposit and then upwardly through Ithe deposit in the direction of the arrows 35. The flushing water progressively urges the liquefied bitumens through the

valve passages

9 and 9A, 10 and A into the casings 3 and 3A. The liquid bitumens can then be tapped from the supply tube 36 extending from the pump 21.

During the extraction process the circulation of the heating medium through the pump and supply lines to boreholes I land II can be suspended. However, the heat may be transferred together with the ushing water in a horizontal direction a-l-ong the lower surface of the deposit as indicated at 37 to contact portions of the deposit which previously have not been sufciently heated. As this ushing progresses, the resulting bitumens can be extracted through the cam passages 8 and 8A.

When the bituminous deposit is located in a rock formation which has a relatively great thickness, the treatment of the deposit by the circulation of a heating medium therethrough can be started and carried out in the lower portions thereof. In a similar manner, when the bitumens are susceptible to ow after a sufficient heating, the bitumens can be extractedby introductions of flushing water. This lius'hing water will absorb heat from the rock formation wherein it has been stored and transfer the heat to various portions of the deposit through which the heating medium has not been circulated. Thus, these portions of the bituminous deposit will become owable and can then be washed out through the various passages of the bore in a manner as previously described.

The ooding or flushing extraction is preferably carried out by a flushing water whose viscosity and density are slightly higher than for ordinary water and which also has a slightly increased surface tension.

Thus it can be seen that the present invention provides an effective process and apparatus for the extraction of highly viscous or solidified underground bituminous deposits. By the application of heat to the underground deposit in a manner as previously described, virtually the entire deposit can be rendered ilowable and then extracted by the flushing of the deposit with water. At the beginning of the ilushing operation the water is warmed but as the flushing operation continues the warming of the water may be discontinued and the flushing water may be introduced at a somewhat lower temperature.

To further assist in the comprehension of the present invention, a specific operating example of the present process will next be described in detail.

A bituminous deposit positioned in -a depth of 350 m. and having a thickness of 60 m. and containing tar sands, in which the setting point of the bituminous contents is 70 C., was exploited according to the present invention.

2 bores each having a diameter of 311 mm. were drilled. The bore I was enlarged to a diameter of 520 mm. for a height of 2 rn. begining from the base of the bore,vin order to provide space to accommodate the expansible :shield of the reactor to be mounted therein. A 20 m. section of both bores extending upwardly from their bases was undercut to a diameter of 371 mm. This undercut section was coated with steel wool mats having a thickness of 30 mm. so that a porous layer was formed outwardly of the casing.

The casing consisted of 4an outer casing having a diameter of 188 mm. and center casing with a diameter of 108 mm. Centrally arranged in the center casing was an inner casing having a diameter of 55.9 mm. The -strings of casing were lowered one after the other together with the reactor. After the arrangement of the strings of casing was completed, the strings of casing were cemented into the bore beginning from the surface and extending down over a length of 200 m. The outer casing was provided in the zone of the deposit with apertures distributed over its periphery and the center casing is provided with gate valves, corresponding to each other, but which can be opened or closed, respectively, one after the other only by a rotary movement of the inner casing. The first apertures for introducing solidifying or setting means were arranged 15 m. above the base of the borehole. The first rows of apertures for admitting the circulating medium into the outer casing were positioned 0.2 m. above the porous layer. Further rows of apertures were 20 rn. higher.

After the reactor was lowered onto the base of the bore, its shield was expanded to fill the space provided by the undercutting of the bore.

After the nuclear reactor was charged with normal water, free from reactor poison, as a neutron reliecting layer, the reactor was then brought to its critical state. lts capacity .per hour amounts to 1,000,000 Cal., and its fuel charge is :calculated to deliver power for two years.

.After the reactor had become critical, 15 m.3/h. of light fuel oil were introduced under pressure from aboveground into the bore as a heating medium by means of the pump connected to bore I, through the center casing at a pressure of 60 atmospheres and heated to C. in the heat exchanger of the reactor. The hot oil owed through the porous layer `upwardly along the outer casing and then entered through the opened lowermost entrance aperture into the outer casing and was extracted in the upward direction. Then it was again introduced down through the center tubing by means of the pump. It was heated again in the heat exchanger and then recirculated into the deposit. After 15 days have elapsed, bore Il, which did not have an individual heat energy source, was connected to the circulation system via the center casing of bore I. After the entire system was filled up, the circulating quantity of oil was maintained constant. The pressure and the temperature as well as the quantity and the characteristic data of the oil supplied to the pump were continuously controlled. After 50 days, variations of the mentioned values indicated that the solid bituminous contents in the lower part of the deposit section surrounding the bore had liquefied to a far-reaching extent and were taking part in the heat circulation. By rotating the inner casing, the lower inlet aperture into the outer casing was closed and the inlet apertures positioned 20 m. higher were opened. Bore II was subjected to the same operation.

After another 30 days, the circulation was interrupted `and the inlet aperture into the outer casing closed by a corresponding rotation of the inner casing with the cams xed thereto, and the exit aperture positioned in the lower portion were simultaneously opened. Through the last-mentioned aperture, 6 m of cement milk were discharged at a pressure of 70 atmospheres for enlarging the heat circulation away from the bore and subsequently, after .a setting had occurred, switched over again to the heat circulation. Subsequently the same operation was carried through in bore II. l

50 days later the circulation was switched to the uppermost inlet aperture. The progress of the heat circulation was controlled by means of a temporary interruption of the oil supply to bore II and a simultaneous throttling of the oil discharge at bore I. After another 12'2 `days yan increase in the pressure at bore II indicated that a connection had been effected between the two bores and that the bituminous portion of the deposit contents located between them had been heated and liquefied.

After a total of 343 days had elapsed, the circulation o-f the heating medium was stopped. Subsequently, 6 m.3/h. offprepared liooding water were supplied to the base of the Ibore at a pressure of 60 atmospheres and the extraction of a quantity of heated deposit oil corresponding to the quantity of supplied water was started. A1- together 21,800 mf of oil have been extracted hitherto from the deposit and the extraction was still going on after 145 days of extraction.

Under favorable conditions in a deposit, several auxiliary bores can be concentrically arranged around the central bore being provided With the source of heat energy and connected to the latter one for providing heat circulations.

It will be understood that this invention is susceptible to further modification and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What is claimed is:

1. In an arrangement for the extraction of underground highly viscous bituminous deposits, the combination of a cent-er casing and a pair of inner and outer concentric tubular casings extending into an underground bituminous deposit, a source of heat energy connected to the center casing adjacent the lower end thereof, means dening a plurality of passages vertically spaced in said outer casing and staggeredly positioned thereon, rotary valve means for selectively .opening and closing said passages, a permeable layer of solid material on the lower end of the outer surface of said outer casing and extending over about one third the height of the deposit, and a pump connected in fluid communication with said outer and center casings for circulating a liquid therethrough.

2..In an arrangement for the extraction of underground highly viscous bituminous deposits, the combination of a center casing and a pair of inner and outer concentric tubular casings extending into an underground bituminous deposit with said center casing being rotatable, a source of heat energy connected to the center casing adjacent the lower end thereof, means defining a plurality of passages vertically spaced in said outer casing and staggeredly positioned thereon, rotary valve means actuated by said center casing for selectively opening and closing said passages, a permeable layer of solid material on the lower end of the outer surface of said outer casing and extending over labout one third the height of the deposit, and a pump connected in iiuid communication with said -outer and center casings for circulating a liquid therethrough.

3. In an arrangement for the extraction of underground highly viscous bituminous deposits, the combination of -a first-.bore having three concentric tubular casings extending into an underground bituminous deposit, a source of heat energy -connected to the center casing adjacent the lower end thereof, a second bore also having three concentric tubular casings extending into an underground bituminous deposit and spaced from said first bore, means for connect-ing the inner casings of said first and second bores so that a fluid medium heated by said source of heat energy in said first .bore can be circulated to said second bore, means defining a plurality of passages vertically spaced in said outer casings and rstaggeredly lpositioned thereon, rotary valve means for selectively opening and closing said passages, a permeable layer of solid material on the lower ends of the o-uter surfaces of said outer casings and extending over about one third the height lof the deposit, and a pump connected in uid communication with said outer and center casings of said bores for circulating a liquid therethrough.

4. In an arrangement for the extraction of underground highly viscous bituminous deposits, the combination of a first bore having three concentric tubular casings extending into an underground bituminous dexposit, a source of heat energy connected to the center casing adjacent the lower end thereof, a second bore also having three concentric tubular casings extending into an underground bituminous deposit and spaced from said first bore, means for connecting the inner casings of said rst and second bores so that a iiuid medium heated by said -source of heat energy in said first bore can be circulated to said second bore, means defining a lplurality of passages vertically spaced in said outer casings and staggeredly positioned thereon, rotary valve means for selectively opening and closing said passages, a permeable layer of solid material on the lower ends of the outer surfaces of said outer casings and extending over about one third the height of the deposit, an aboveground pump ydischarging into an intermediate tank, return lines from the outer casings of said first and second bores to said intermediate tank, and supply lines from said pump to the center casings of said first and second bores.

References Cited by the Examiner UNITED STATES PATENTS 895,612 8/1908 Bake-r 166--57 2,044,657 6/1936 Young 166-74 2,277,380 3/1942 Yancy 166-74 2,801,090 7/1957 Hoyer et al. 166-60 X 2,874,777 2/1959 Tadema 16S-ll 3,004,600 10/1961y Henderson et al. 166-39 3,055,423 9/ 1962 Parker 166-11 3,080,918 3/1963 Netland 166-11 3,120,264 2/1964 Barron 166--39 CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner.

S. I. NOVOSAD, Assistant Examiner.

Claims

1. IN AN ARRANGEMENT FOR THE EXTRACTION OF UNDERGROUND HIGHLY VICOUS BITUMINOUS DEPOSTIS, THE COMBINATION OF A CENTER CASING AND A PAIR OF INNER AND OUTER CONCENTRIC TUBULAR CASINGS EXTENDING INTO AN UNDERGROUND BITUMINOUS DEPOSIT, A SOURCE OF HEAT ENERGY CONNECTED TO THE CENTER CASING ADJACENT THE LOWER END THEREOF, MEANS DEFINING A PLURALITY OF PASSAGES VERTICALLY SPACED IN SAID OUTER CASING AND STAGGEREDLY POSITIONED THEREON, ROTARY VALVE MEANS FOR SELECTIVELY OPENING AND CLOSING SAID PASSAGES, A PERMEABLE LAYER OF SOLID MATERIAL ON