PERMFILE126999 - Laserfiche WebLink

Home Browse Search

- .. ~ • 7 3,759,328 horizontally separated patterns that each contain one or more wells opening into a layer rich in water soluble minerals can be operated as described in connection with FIG. 2 to form horizontally expanding permeable zones and produce shale oil. The sizes of the permeable zones can bt monitored by means of acoustic, clccvo- magnetic the like mcasuremenu of the esunu a( the mbstantially void space and/or measurcmenu of the volume of fluids that arc contained into caverru. Thc horizontal expansi°n oC the eavcma tan be controlled to provide an efficient recovery of oil Gom nonintcr- sccting, generally vertically extensive zone6 that are spaced w that undisturbed columns capable of sup- porting the orcrburAcn art Icft between the depleted zonct. During the initial stages of tspanding a ruhble- eentaining cavern m accordance wth the present pro- cess, it is not necessary and is generally undesirable to use a trmperatuct high enough [o decompou a pre- dominant proportion of the fluid-contacud hear unsi- tirc eaibonetc material. Il u preferable to keep the eav- crn substantially full of aqueous liquid in which the car boosts material is soluble. This unds to provide the hest heat C<Onomy since ii minimizes the decomposi- tion reaction (which is an endothermic reaction that eomaumcs heal). In order to keep the cavem substan- tially filled with aqueous liquid it is preferable w main- tain [he pressure within the eavcrn abort the dec°mpo- sition pressure of the brat atnsltivt rarbonatc material at the temperature within the cavern. !n general the pressure within the cavem cannot be kept high enough . [o prevent such a decomposition during an oil recover- ing stage. The retorting and hydr°carbon recovery is preferably conducted at a [emperawre above about 500 F, and at the depths at which od shale is usually encountered, [he pressure in the cavem cannot be h,gh enough to prevent decomposition o! heat sensitive car- bonate material at Such a temperature, without a dan- ger of creating large eesle fractures which are extended into lOCatlOns in which fracwres art undesirable. When one or a plu slit}' of generally vertically extcn- sivc permeable xoncs have been capandcd horizontally t0 substantially the extent desired, the cir<ulaUOn of fluid within throne zones or caverns u preferably ad- justed to minimize the rate oChorizontal growth and/or mazimixc Iht rate of oil rerovery. Such an adjustment can be eKected by increasing [he temperature and/ot dccrcasing the aqueous liquid content of the fluid within the eavcrn. A higher temperature tends to in- crease the rate of oil rrr.overy (particularly with re- ^pect to the gaseous eomponenu of shale of ). AJtema- tively, a decrease in the aqueom liquid coots rat tends to redur. r. the rate of dissolution of aoluhlc mineral. Where the removal of solid material horn the oil shale la confined to a removal of the fluid products of the py- ralysi^ rcaeliun and/or the COs and water vapor pro- duced by the decomposition of hw[ semitive carbon• aces, the volume of the depleted oil shale unds to be sufficient, relative to the volume of wlids that are re- moved, to tcrminau the growth o(the permeable mne (unlcv the od shalt is one Nat contains an exec ption• ally large proporl5on °f heat scnsilive Carbonate min- eral). The aqueous liquid conunt o(Iht tluid within the eavcrn can be reduced by, for example, circulating m!} ctantially dry steam, nr a mizturc o(e dry steam and e.g„ carbon di°xid0. at a rate and tcmperawm et which GU _+ .J r 70J r . rJ~ YJCJ 8 aqueous liquid lift within thG eavcrn contains a rela- tively high proportion of inert inorganic salute. FlG. 3 shows downhole equipment of the type shown in FlG. 1 arranged to et7e[t a downholc xpuation of 5 the gaseous and liquid phases of the fluid being pro- duccd. particularly when the concentration o(heat sen- sitive carbonalt material is relatively high, and/or the temperature of the inflowing hot aqueous fluid u rela- tively high, a significant amount of gquous carbon di- 10 oxide and water will be formod. However, to the extent that it is feasible, it is desirable w produce a relatively tool liquid phase fluid that con[ainrs a zignificanl pf0- portion oC produced shale oil hydrocarbon. In [he ar- rangement shown in FlG. 3, borehole 20 is equrppcd 13 with pipe strings 21, 22 and 2J. Some or all o[ such pipes etc preferably thermally insulated, as indicated by coatings 2A on pipes 21 and 22- pipe 21, through which the hot aqueous fluid is inflowed, opens into the borehole et a relatively shallow depth. Pipe 22 extends 20 to an intermediate depth and is used to outlow fluid [he[ u relatively tool but is predominately gaseous. Pipe 23 extends to a relatively deep depth, is preferably equipped wish downhole pumping means (not shown), and is uxd w outflow fluid that is predominately liquid. 23 'pet vertical xction of bo[chule between the ends of pipcf 22 and 23 urvex as a downhole gravity of upara- tion chamber. Steam or a mix tore °C steam and hot aqueous liquid (hot water) it inflowed through pipe 21. Thc inflowing 30 hottest and lightest gaz tends to remain above the cooler and heavier gas and N situ generated carbon di- oxide. The cooler gaits outflow through pipe 22 while the hones and lighter inflowing gases tend to flow along the walls of the cavem. Where desirable a rclaucely 33 light and cool gas, such as methane, hydrogen, etc., can be maintained substantially static, or slowly injected, through anA around the upper p°rtion of the borehole and cavern. Once the nibbled oil shale cavem has been estab- 40 lished and the heat sensitive minerals and water-soluble carbonates removed as an aqueous solution, the hydro- carboru (oil)can be recovered by suitable means such az by contacting the nibbled oil shale within the tavern with a pyrolyring fluid to effect decomposition o! the 43 kcrogens to hydrocarbon which a removed from the formation. In recovering the hydr°carbons, the pyro- lyzing fluid can be injected (FIG. !) via 7 and reeov- ered via cubing g visa versa and in a dual sytem as shown in FIG. 3 the pyrolyring fluid ouch as steam can ' So be injected via mbing string 21 and the hydrocarbon ~ recovcrcd vie 22 or the proccse can be revcrxd. It is understood that various changes in the detailed described to captain the invention can be made by per- 55 sons skilled in the tit within the scope o(the invention as cxpsessed in the appended claims. - 1 claim az my mvcntion: t 1. In a process for expanding a zone of pcrmeahility within a subterranean oil Shale by forming a permeable ~ zone within a portion that eon[ains heat Xnsitive cu- bonatc mineral and circulating hot aqueous ^uid within the permeable zone, the improvement which com- p(IXS: irtflowing hot aqucoua fluid into contact with ssub- 63 Icrrancan portion of nil shalt that contains heat unsitive carbonate mineral at a relatively shallow depth, the tr.mpesatufc of acid inllowing fluid being