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<br />sla- The in0ou•ing hot aqueous fluid can be heated by is rich in water soluble ml
<br />neral and(or heat unsitive
<br />:composing means of surface located and/or downhole located, carbonate mineral. Such wells arc uxd to form an in-
<br />tents o(:Ihe seam generators, water heaters, or the like. AI[ema• (low path 14 and an outflow path 15 that are intereon-
<br />of partiulles Lively, or additionally, such heating can be effected or netted by a path eztnding through an areally extensive
<br />I
<br />:izontal ez• supplemented in an insitu combustion within the oil 5 cavern 6. As indicated by the arrows, hot aqueous fluid
<br />~ane of pcr• shale formation. The temperature of the inllowing hot
<br />° is inflowed into contact with oil shale containing heat
<br /> aqueous fluid can range from about 250
<br />F w one sufli- sensitive carbonate material at a relatively shallow
<br />.s a signifi- cient to tauu a relatively rapid oil shale pyrolysis, e.g.,
<br />°
<br />° depth, (lowed down along a vertical section of such oil
<br />e, whic)i is a temperature oC from about 600
<br />to 5000
<br />F. shale, flowed along the root ota horizontally extensive
<br />~
<br />:ing of hot The inflou~ing aqueous liquid phau oC the hot aqua- 10 coven within such oil shale, and, liquid containing dis-
<br />:d by a Cir• ous fluid dissolves naturally water soluble minerals solved mineral material u removed from within the
<br />v tempera- such as nahcolite, trona, halite, or the like, and/or horizontally extensive cavern. Such a horizontally ez-
<br />tempera- water soluble decomposition products from a heat un- tensive coven can advantageously be formed by means
<br />such a pre- sitive carbonate material, such as nahcolite, eft., to of mechanical hacturing, and/or solution mining tech-
<br />zut signifi- create solid•frce space within the oil shale. Various IS piques, for example, by one or more of such techniques
<br />-Its of the ss•atcr soluble mincrals, such as nahrxolite (NaHCO,), described N the about mentioned copending patent ap-
<br />:rea of ex• may dissolve prior to any thermal decomposition, if the plications.
<br />for lavers pressure is su~cientJy high at the temperature of the A principle advantage of a flow path of the type
<br />~t circula- inflowing fluid. Alternatively, such minerals may be shown in FIG. 2 u the heat economy and the fact that
<br />.he rate of partially or wholly decompoud to gauous fluids and 20 much larger volumes of oil shale can be rubbled per
<br />roportidn sodium carbonate before dissolution. unit time than could be achieved by either a horizontal
<br />:irculated Al[hough the portion of oil shale formation which is or vertical rabbling by itself. Relative to horizontal rub-
<br />'Is' heated treated in accordance with the preunt inr'ention must tiling from a single well, the eoncurrcnt vertical and
<br />not aoue- contain a signincant amount of heat xnsitive carbon- horizontal rvbbling is capable of providing much higher
<br />:arbonaie ate material, it may contain uc[ions, or vertical inter- ''-5 oil production rates, particularly in [he early stages of
<br />the flow vats of as much az several tens of feet thick, which are the process. Such a flow path can be utilized to produce
<br /> substantially devoid o(heat sensitive and/or u~atet solu- a «latively cool fluid with much o! the produced hy
<br />.:xpansioh tilt minerals. In such heterogeneous regions, the heat drocarbon and injected fluid being outflowed in the liq-
<br />nd main- sensitive or soluble mincrals are convened or dissolved aid phase.
<br />th•~ ~( and removed. Portions of the so-convened oil shale 30 A flow path oC the type shown in FIG. 2 can be initi-
<br />a~ n materials become incompetent and break into pieces a[ed between one or more pairs of wells. Initial comm~-
<br />tnan~, in under the existing local stress field. Such pieces, or nication is preferably achieved by fracturing or dissoly-
<br />he space chunks, of oil shale mineral materials tend to accumu• ing within the layer of water soluble material until (laid
<br />onion o[ late on top of {edges of oil shale that contains little or injected in one well can be produced from another. Ho[
<br />the too( no heat sensitive or soluble material. The accumulation ~S aqueous fluid is then injected at the top o(an injected
<br />.:Is of the o(weight from such chunks, together with the existing well and Fluid is produced from within a generall• hor~~
<br />he loco= stress field, cause such ledges to break into pieces and zontal cavern or flow path through a production well.
<br />I fall to a lower level. The action of converting kerogen The upper portion o(the injection well will enlarge lat-
<br />C1z.e~; into shaft oil materials such az gaseous and liquid hy- orally and the lower portion or rubble-containing cav-
<br />aqueous drocarbons enhances such an operation and, where the a0 em will enlarge vertcally so that the permeable zone
<br />The hot oil shale is relatively lezn with respect [o heat unsitis'e is expanded both laterally and vertically. ]t is in the
<br />~ g at. and soluble mzterials, the use o(hot aqueous fluid heat lower region of the rubbletontaining cavern that heat
<br />hart the. to a kerogen-pyrolyzing temperature is desirable. Also improvements are made. With such a flow path, nc~ m-
<br />ale for-~ hydrocarbons can be extracted from the iubbled oil (lowing fluid preferably has a temperature below one at
<br />yid con-; shale by solvent means such as b}• use of phenols, aro- a5 which the pyrolysis of kerogen is rapid. Where it is de-
<br />tarbon: matte solvents, e.g., benzene, xylene, etc. sired to rabble large volumes of oil shale while remov-
<br />~e nor-: Due to mechanisms such az those mentioned above, ing solid materials and preheating the shale for later py-
<br />eration ~ ~ the application of the preunt process causes a gaper- rolysis, such a use oC a relatively low temperature re-
<br />o(the : ally vertical cavernous zone to grow N a horizontal di- subs in significan[ hea[ economy. ucommunication be-
<br /> rection. The ra[e of growth will vary depending upon 50
<br />tu~een different pattems oC injection and production
<br />ng hot : the heat sensitive and water soluble mineral con[en[ of wells is desired the depth of the location from which
<br />.td ere-' ~ the particular zone. The outer boundary of the zone liquid is produced can be kept relatively deep within
<br />;along . "ill generally be very irregular with portions extending the soluble layer so that the circulating fluid will contai-
<br />F. pad several tens of feet to rther than others. in order to cn- ss nut to enlarge the areal extent of the dissolved zone.
<br />~.issolu- hence horizontal growth while injecting a hot aqueous 14'here communication between different well pattems
<br />ubblc- I fluid that is prcdominently liquid, it is generally desir• is not desired, the production point and production ra[e
<br />;id can i I able to maintain moat or all of the rubble{ontaining can be adjusted to leave a substantially saturated liquid
<br />:izture + cavern full of liquid. Altcmativcly, when the injected solution in the soluble la}'er in order to prevent its tut-
<br />or , hot aqueous fluid is steam, it is generally preferably to 60 the; groulh.
<br />ns,'~ keep much o(thc rubble-containing kerogen filled with Such a versatility with respect to the size and shape
<br />.ke, or steam end/or gaz. of the cavernous zones that are formed before and/or
<br />az an A particularly suitable arrangement of (low paths to during a recovery of shale oil is a unique advantage of
<br />Vhcrc be used in the present process u shown in FIG. 2. At the preunt process. For example, where the oil shale
<br />-stows (cast two horizontally separated wells arc opened into 6y is thick, large amounts of shale oil can be recovered
<br />:gnifi- a region of oil shale that contains heat sensitive carbon- from a cries o(zones that are vertically extensive but
<br />.'ithin ate mineral and is located immediately about a layer or arc horizontally spaced so that problems due to subsi-
<br /> zone of oil shale or other earth (ormetion ma[erial that dance arc avoided. For example w~llc in , olurali tv mC
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