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~tH-21-1`J`J`j 1-r2~ lit Ntk'HL LT~~'III.FIL L~CS P. 02108 . t r 1 • 3,759,328 +x t( ~aa- =compo mg '+cntf of~c of parti~Ics rlxen[al I~ x- ~ne of dCt- 1 t a sigrrjfi- c, v. hicf~ is tog of hot :d by a fir .' temper- = tempefa- mch a per rut signiG• Ies of the ~.rea of cz- for lavers it cLCnla- he rate of roportidn rucula tfd 'Iy heated not aquc- _arbona[e the (low zpansion nd main- ; the" f ari, n tnarv, ip he spacq ~rtien o! the too( Is of the he Iota= cavem~ aqucou~ The hob e g , ail ban the: ale for ' ~d con carbon' ~c nor-: station ~ oC [hc: ng hot td ere- . alo nq , path lissolu , rrbble. ~ .rd tan , ~ axtUft or ' ns,`,. kc, or as an 4hcre ~seous :gttifi- a3 whin The inflowing hot aqueous fluid can be heated by means oC surface located andlor dowrhole located, steam gencre[ors, water heaters, or the hke. Alrcma- tivcly, or adduionally, such heating can be effected or supplemented in an insitu combustion w~thm the oil shale (Donation. The tcmpcrature of [he inlloving hot aqueous fluid tan range from about 2S0' F to one tuffs eient to cause n relatively rapid oil shale pyrol)•sis, e.g , a tcmpcrature of from about 600' to 1000°F- The inll0wing aqueous liquid phau of the hot aque- ous fluid dissolves naturally water soluble minerals such u nahcolitc, trona, hoists, or the like, and/or water soluble decomposition products from a heat sen- sitive carbonate ma[crial, such u nahcolttt, etc., w create solid-free apace within nc~ oil shale. Various water soluble mrncrals, such as nahocolite (NaHCO,), may drssOlve prior to any thermal decomposition. if the pressure is su~ciendy high at the tcmpcrature of the intlowing fluid. Alttmatively, bath mrncrsls may be partially or wholly decomposed to gaseeus fluids and sodium carbonate before dittolution. Although [hr. portion of oil shale lorma:inn which u treated in aceOrdanee with the prescnt invention must contain a significant amount Of heat unsitivc carbon ate material, i[ may tents in aee[jens, or vertical inter- vals of as much as several tens of feet thick, which arc substantially devoid of heat unsitivc andlor warty solo ble mint-rats. In such heterogeneous regions, the heat sensitive or soluble minerals ate converted or dictOlved and removed. Ponjons of the socOnvcrted dd Shalt materials become incompetent and break into pieces under the ezisung local stress field. Such ptcces, or chunks, of oil shalt mina al mamrials tend to accumu- late en top of ledges Of oil shale that contains pule ^r no hwt sensitive or soluble material. The accumulation of weight from such chunks, together with the existing strew field, cause such ledges to break into pieces and fall to a lower level. The action of converting kerogen into shale oil matcnals such as gauuus ar.d liquid hy- drocarbons enhances bath an opcratton and, where the oil shah rs relauvdy lean a•rdr reaper to heat unsr[ive and soluble materials, the use of hot aqueous fluid heat to a kcrogen~pyrolyzing eemperamre is dcscahlc. Also hydrocarbons can be extracted Crom the rubbled ail shale by solvent means such as by use oC phenols, aro- matic solvents, e.g ,benzene, zylcnc, etc Duc to mechantsma such as those mentinncd above, the application of the presto[ process sautes a gener- ally vertical cavernous zone t0 grow in a horizontal di- rection. The rate of growth will vary departing upon the heat tcnsrtrve and water soluble mineral content oC the particular zone. The outer boundary of the zone will gene ally be very irregular wrth parsons extending sevcrpl tens of Cctr further than others. In ordu to en- hance forizontal growth while injecting a hot aqueous (laid that is prctlominantly liquid, it is gcnc:911y desir- able to maintain roost or all of the rubbletontaining cavern full of liquid. Alternatively, when NC infected hot aqucou6 fluid is steam, i[ is generally preferably [o keep much of the rubble-containing kcrogcn 611cA with steam and/or gas. A particularly suitable annngement of (low paths to be weed rn the prescnt process is shown m FIG. 2. At Itast two horizontally scpnrated wells arc opened into e region oCoil shale that contain heat sensitive tar bon- ptc mineral and is located immediately shoot a layer or zone of oil shale nr other earth formptton ma:etiel Chet • 6 is rich in water soluble mina al nndlot heat unsitivc carbonate mineral. Such wd(t arc tu:ed to Corm nn in- flow path 14 and an oudlow path 15 that are intercon- netted by a path extending through an areally extensive 3 cavern 6. As utdirated by Ne arrows, hot aqucatu fluid rs in(lowed into contact tvj[h oil shalt containing heat tcnsitive carbonate materta] at a relatively shallow depth, flowed down along a vertical section of such oil shale, flowed along the roof Of a horizontally extensive 10 tavern vvjthin Such oil shale, and, liquid Containing dis- solved mineral material u removed from wtthin [he horizontally cztcnsive raven. Such a horizontally ex- ecnsrvr. cavern can advantageously be Corned by means Of mechanical fracturing, and/or aOlution mining teeh- t 5 ntques, for example, 6y one or more o(cueh techniques descnbcd in the above mentioned copending patent ap- plications. A principle advantage O[ a flow path of the type shown in F1G. 2 u the heat economy and the (act that =0 much larger volumes of oil shale can be cobbled per unit time than eO01d be achieved by tither a horizontal or vertical nibbling by itself. Relative to horizontal r~b- bling from a single well, the eonttrrrent vertical and horizorsul rabbling b capable of providing much higher 'z-5 oil production rates, particularly in the early stages of the process. Such a Oow path can be utilized to produce a raises vcly cool fluid with much of the produced hy- drocarbon and inlccttd fluid being outflowed in the Ilq- uid phase. ~0 A Dow path of the type shown in FIG. 2 can be int[i- ated bctw•een one or more pairs of wells. Initial cOmmu- r.icauon is prcfcnbly achrcvcd by fracturing or dissOly- mg within the layer of water soluble material until fluid rnyected in one well can be produced from another. Hot J5 aqueous tluid is then injceted at the cop of an injceted well and fluid tt produced from within a generally hori- zontal cavern Or flow path through a production well. The apps[ parson of the injection weQ will enlaigc 1at- crally and the lower portion or rubble-containing cav- a0 em will enlarge verdeaily so that the permeable zone is expanded both laterally and vertically. It is in the IUwq region O! the rubble-containing eavcm that heat improvemenu arc made. With such a ^ow path, the in- flovnng fluid preferably has a temperature below one a[ 43 v,hicli the pyrolysis oC kerogcn is rapid. Where it is de- sricd to rubble large volumes oC oil shale while remov- ingsolid materials and prthcating she shale Cor later py- rolysis, such a use o(a relatively low Icmperamrc re- sulu u: sign¢icant heat economy. lleommunication be- 50 [wean d~ffcrent patteme o! injection and production wetly is desvrd the depth of the location from which liquid rs produced can be kept relatively deep within [hc soluble layer so that the circulating fluid will ~orta~~ 55 rue to enlarge the azcal extent oC the dissolved lone. Whcrc communication lx twecn dine rent wet! patterns is not desired, the prtduction point and production rate can be adjusted to leave a substantially sa[uratcd liquid solution in the soluble layer in ocder to prevent its fur- 60 ihcr grow•tIt Stith a versatility wth respect to the size and shape of the cavernous zones thin arc formed before andlor dur{ng a recovery of shalt oil is a umqur advantage of the prescnt process. For example, where the oil shale 65 is shirk, large arnauntt of shalt Od can be recorcrcd from a arses of zone that art ve Ritafly eztcnsjvt hue arc horuontally spaced us that problems due to subsi- dence arc avoided For cramnl. ,...u. ~.. , ~f.,~uti ,.r