CA1112561A - Method of thermal-mine recovery of oil and fluent bitumens - Google Patents

Abstract

METHOD OF THERMAL-MINE RECOVERY OF OIL AND FLUENT
BITUMENS

ABSTRACT OF THE DISCLOSURE
The method of thermal-mine recovery of oil and fluent bitumens or kerogens includes providing a system of mine workings above an oil-bearing formation and drilling from these workings and from the ground surface a series of injecti-on wells into the oil-bearing formation. An operation gallery is provided within the oil-bearing formation, from which a system of horizontal and inclined recovery wells is drilled. Then a heat carrier is positively injected into the oil-bearing formation to heat it to a temperature whereat the oil attains the required fluidity within the formation.
Then a fluid is charged into the formation to force the oil from the oil-bearing formation into the horizontal and inclined recovery wells, toward the operation gallery, from which the oil is directed to the ground surface. The improvement of the method resides in that the heat carrier is injected into the formation through the horizontal and inclined recovery wells extending substantially across the predominant direction of the highly permeable zones of the oil-bearing formation, and, following the heating of the formation to the above said temperature, the injection of the heat carrier is terminated, and the fluid is charged into the injection wells having minimized association with the highly permeable zones of the oil-bearing formation, to force the oil from the oil-bearing formation through the recovery wells toward the recovery gallery.

Description

Z56:1 ~}IO~ Ol~ L~rIIl~E læC0-~3RY 0~ OI~ i`ii~ r~
Bl~ S

~ he iilvention rela-tes to recovering oil ~rom hi-~;h~
viscous oii-b~arin~ ~orma-tions, and, more particularly;
it relates to a me-thod of thermal-mine recovery of Gil and fluent bitumens or l~erogens.
~ he invention ca~ be utilized -to utmos-t e~fectiveness for recovering oil from fissured and incoherent oil-bearina s-trata.
~ he invention can be also utilizee for recoverin~
o~ rom exhausted oil-bearing strata.
At present 9 oil-bearing ~ormations of -the abovementioned kinds cannot be developed by the conventional technique o-~drillin~ boreholes ana wells ~rom -the ground sur~ace 9 on account of the oil yield bein~ in such cases -too small ~or practical purpose s.
~ ere is known a method o~ mining recovery of highly viscous oil from oil-bearin~ forma-tions or beds, according -to which oil is removed to -the ~round surface -ts~e-ther ~jith the oil-bearing shale or rock. ~le me-thod încludes recover~
o~ oil b~ providin~ subterranian mine worl{in~s within the oil-bearir~ formation, a~d subsequent imploding o, -t,~lese ~orkin~s (see9 for e~.ample, the US Pa-tent No. ~9437,373;
~l. 299-2, filed ~ebruar~ 02, 19679 dated A~ril 03, 1964~.
~ his known method, ho~ever~ is labour-consumi~ and costly.
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~ 2s des, it i~lvolves defirlite hazarGs co~ c~d -;i-;
the s.ibsequent implodin3 o~ -the mine l.o~kings.
In add.tion to that~ the method affects ~hr worki.l;
environmrn-t and sa~ety of -the perso~nel, because whe~ Oil is rernoved to~ether wi-t~ the rock or shale con~ainir~ it~ as the mine workinOs are bein~ excavated7 gases and oil issue irom the oil-beari~ forma-tion into these ~vorkinOs; further~o-re, P~hen cil is recavered ~rom an incohere,lt oil-bearirlg bed, spo~-taneous caving-in of the workinOs might OGCU~v There is further known a mining method of recove~i~g oil from oil-bearing beds, accordir~ to wnich mine workirlgs are provided in impermeable rock underlyinO the oil-bearin,, formation, and series o~ wells are drilled therefrom.
~hen high-velocity whirlir~ je-ts o~ liauid are directed through these wells into the oil-beari~g bed; to fo~ a slurry whic~ is withdrawn from the bed (see the US Pa-tent No. 3,934,935; Cl. 299-2, da-ted January 27, 1976)/
However, this method, too, is e~cessively labour-consuming and costlg. ~urthermore~ it is significantly compl-icated in its implementation, o~ account oï the great quantities of sand washed awa~ wi-th the oil from -the oil--bearir~ bed.
~ here is knowrl still another method of mininO recovery of oil from an oil-bearing bed, without rerrlovin~ the rock or shale containinO oiI to the ground surface ( see article by V.P. ~abakov "On Influence OL ~lell Netl,york I~ensitv ~"~pon :`
Oil ~ield, as Illustra~ed by Yarega Field EY.perience`' /in Russian/~ in ScientiYic-Engineering ~qanual on Oil Pxoduc-tion9 ~o. 41~ VNIIN2ft, "NEDRA" Publishers, Mosc~ 197'i, p. 155).
~ he method includes providing a system o~ minc worki~s above the oil-bearing bed. ~he mining ~ield is divided into a plurality o~ levels. ~ongitudinal field dri~ts are provi-ded intermediate the levels, and drilling chambers are made ;therein. ~rom these drilling chambers inclined and vertical wells are drilled into the oil-bearing bed, down to the bottom o~ the bed. The wells are uni~ormly spaced throughout the oil~bearing bed.
;~he spacing o~ the well ~aces, the number o~ the wells and the pattern of the mine workings may vary as this method is implemented, depe~ding on the properties o~ the oil--bearin~ bed, its thickness and physical-chemical properties o~ the oil.
The structure of the wells re~uires their provision with casi~g columns, the voids between the casing pipes and the well wall at the well mouth being sealed with a cemen~ing composition. The well ~aces remain open. A lift pipe string is lowexed i~to t~e casing column, and ditches are made at the well mouths along the mine worki~gs with an appropriate sloping angie ~or exposed ~rae gravity ~10YJ 0~ oil ~rom t_e wells tovard colle_tion tanks.

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~ t -the ini~ial stage of the opera-tion ol the -.,ells oil, as a rule9 Oushes there~rom, and -vhen the Oushin~ ~ es a~iay, air is pu~ped into the space between the casing anG
the li~t pipes.
To p:rovide ~or better gravi-ty flow of oil, water is supplied into the di-tches o-~ ~he mine workings. Oil collect-ed in the tan~s is separa-ted from water, heated up and pumped to the ~round sur~ace.
However, experience shows that ~Ihen the last-descIibed method is implemented in oil-bearin~ beds with hi6rhly viscous oil~ the yield is too low.
~ urthe~ore, the implementatlon o~ this method involves a great volume o~ mining wor~ and drillin~ a Oreat amount o~ wells uniformly spaced -throughout the oil-bearin~ ~ors1a-tion.
The above-mentioned method requires hi~her costs ~`or ting oil after its gushing is stopped.
3esides, -the ~reat number of operating wells uni-~or~ly spaced throuOhout the oil-bearing formation compllcates the monitoring OL the performance o~ individual wells, their maintenance and repairs.
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The abovediscussed di~ficulties have brought about the need for developin~ oil recovery methods based on exerting ph~Jsical-chemical action on -the oil-bearing bed itself;
and on the fluid saturating this bed.
There is further know~ a thermal-mine method o~ oil ~ 5 recovery by exer-ti~ steam and heat ac-tion upon an eil~
-beari~ bed (see article by ~.M. Rusin "~periellce in PUmP~ -team into ~issured-Porous Bed of Yare~a Field ~in ~ussian/, in the already mentioned Scie~ti~ic-En~ineerin~
Mallual on Oil Production, ~o 41, V~ Teft, "l'~E~ ' Publishers~
~o~cowt 1~71, p. 109).
The method includes providi~g a s~ste~ o~ mine work-ings above an oil-bearing bed.
Vertical and inclined wells are drilled ~rom thes~
mine workin~s. Pipelines are constructed in these above--bed mine worki~s for the heat-carrier SUpply9 and sone of the wells are connected thereto. ~hese wells are operated as injection ones, through which the heat carrier, e.~.
steam is injected or char~ed into the oil-bearin~ bed to heat the bed and to force oil in-to the rest o~ the wells~
operated as recovery ones. The injection and recovery wells are al-ternated and spaced uniforr~ly throughou-t -the oil-bea-rinO ~ormatio~ The mouths ol the recovery wells are open, for free gravity flow of oil dow~ the inclined di-tches OL the mine wor~in~s toward collecti~g tanks. The ~ouths of bo~h injection and recovery wells are provided with gate means.
At the inital period of the operation, with the oil--bearing bed being heated up with the heat-carrier, oil ~ushes from the wells, and when the gushing dies awaJ7 air is purnped into the space between the casing and the lift _O_ pipes to recover oil through the w.ells.
Ho~ever9 this knovJn method requires the drillin~; OL
a great amount o~ wells, since a single well is ins~f~icien-~
eit~er to heat up the oil-bearin~r bed or to recover oil there~rom,particularly, i~ the bed is relatively thin.
: ~urthermore~ the method involves addi~ional costs connected Y~ith supplying compressed air to li~t oil throw~h ; the wells.
Moreover, with the same mine ~orkin~s housir~r both heat-carrier injection wells and oil recovery viells, the temperature and gas-content conditions of the v~hole a~mosphere in the mine are a~ected; the wo~king environ~ent and sa~ety of -the personnel are impaired.
; Besides~ there is an eventuality o~ the heat-carri~r ~indin~ i-ts way and bursting into the open recover~ wells.
Such breakthrough o~ the heat-carrier into ventilated rnine : workings significantl~ steps up the consumption of the heat carrier per one wei~ht unit o~ recovered oil.
: Breaks in the operation o~ the recovery and injection wells resul~ in sand pluos ~ormin~, therein, and lead to a co.nsiderable amount of dowrltime of the wells for maintenance : and repair ~ork, which af~ects the per day rate o~ ~he oil yield of` the oil-bearin~ ~ormation.
~ here is also known a thermal-mine metrlod o~ oil reoovery, wherein s system o~ mine workLn s is proviàed sbove .

t`le oil-beariIl;r bed, i~clined at a~l a~,le irol 1 to 3i -to a nori~ontal pla~e (see9 for e~ar~ple, the SU Inver~-tor?s Certificate ~o. 46~ 9 529).
~ rom ~hese rnine workings in~ectio~ wells are drilled ~or chargin~ the heat-carrier and its uni~orm propa~ation chrough the oil-bearing bed. A slope and a r~an way are rov~-ded into the lowar paxt ol the oil-bearîng bed~ and a recovery gallery is provided in this part o~ the bed.
~ ro~ vhe recovery ~allery a sys-tem o~ horizon-tal a~
inclined oil recovery wells is drilled. ~he heat ca~rier is charged into the said injection wells for its uniforrn propa-gation ~hrou~hout -the oil-bearin~ bed and for ~orcirlæ oil into t~e said horizontal and inclined recovery wells;
-toward the said recovery gallery from which oil is wi-thdrawn to thc ground sur~ace.
HoY~ever; the irnplementation o~ -this rnelhod inYolves the drilling OL a great number of injection wells~ to provide ~or uniform distribution ol the heat-caxrier through the oil--bearin~ bed, since a sin~le heat-carrier injection well is by ~ar i~su~icien~ ~or ~aking care of the whole oil-beari~g bed9 particularly wher. the latter is relativelJ
thin.
Furthermore, witn a smaller ~umber o~ inaection w~lls the rate o~ heatin~ of the oil-~earinO bed is loW7 whereby the yield is lil~.ewise low~ which considerab:Ly increases the time of developing the oil-bearin~ ~orma-tion.

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Ver~ non-homoC~eneit~ G the oil-beari.:g j -~ aL'd the lac-t that in most ca.es -the bed has fissures t..erein ould not enable to conduct i~l -the mos-t ef~icient .~anilGr the L~orcin~ of oil by the heat-carrier into -the horizorital j and inclinSed re.covery wells, toward the recovery vallery, .. ~ on accoullt o~ the dor.1inatin~ in~iltration and pro~agation.. o-~ -the lorcing-out flu.id throu311 these fissures and the .~ highly permeable ~.On2S 0~ the oil-bearing bed, which also af~ects the oil yield ar.d prolongs the devsloprrlen-t of the oi~-bearin~ ~orr~ation.
Be~ides, the per day yield of the oil-beari~ bed is a~fected by the ~act that the heat-caxrier is charc,ed throuOh the injection wells, while the near-!ace areas o~
; the reoovery vwells are less heated~ and it is here ~here tne : oil ~low rneets the stron~es-t resistance to its proOress.
In addi-tion to tha~t, the charginO OL the hea-t carrie-into the injection wells drilled ~ro~ the c1ine workings overlyin~ the oil-bearing bed results in eveLI-tual break-throu~h o~ the hea-t-carrier into the inclined and horiz-ontal recovery wells and into the recovery ~allery~ which ~. sharply decreases the rate o~ heatin3 -the oil-bearin~
bed, increases the consumption o~ the heat-carrier~ aL~LDects the ~vorkîng environri~ent and sa~ety o~ the personnel.
~ part ~ro~ ~that, the supply OI -the heat-carrier into : the great number o~ -the re~uiI~ed injection wells drilled _9_ ~`rom -the miile~ ~orkings overlyinO the oil-bearin~ bed~ --o unlLorm propaga-tio~ of the heat-carrier throu~hout -the bed5 steps up -the cost o~ ventilation of the mining workinOs~
on accoun-t of a hi~h degree o~ dissipation of heat into these workings.
It is -the mai~ object OLf the present invention to provide a method of thermal-mine recovery of oi~, which should enable to increase -the per day and total yield of an oil-bearing bed and to cut down the time of i-ts development.
It is a not less important object OL the present in-vention to provide a method o~ ~hermal-mine recovery of oil, which should enable to reducè the cos-t of recovering oil from an oil-bearing bed, to reduce the number of the ~ells required ~or chargin~ the heat-carrier and withdrawin2 oil~
and to mi~imize the complications associated with preparing the oil bed ~or de~elopment and with reco~ering the oil, on account of grea-t quantities of sand evolving from this oil--bearing bed.
It is still another object of the present inverltion to provide a method o~ thermal-mine recover~ of oil; W'!liCh should enable to cut do-~ the cost of ven-tiiation o4 ~he ; mine workings required ~or maintaining the neces~ary ~as--content and ter~perature characteristics OL the atmosphere the mine, to enhance the working environmen-t and safety o~ the personnel.
These and other objects are a-ktained by t~e creatiGn . -'1 0-o~ the riiethod of thermal-mine recovery of oil7 includi~:
providing a system o~ mine working above an oil-bearin~
for~ation or bed; drillin~ from these mine workings and/or fror~ the ground sur~ace a plurality o~ injection well 5 ~or charging a fluid into the oil-bearing bed; providing a slope and a man way in the area o~ the oil-bearing bedj providing a recovery gallery in this area of the oil--bearing bed; drilling from the recovery gallery a system o~ horizontal and incli~ed recovTer~ wells for recovering oil9 charging a heat-carrier into the oil-bearing bed for heatin~ same to a tempera-ture whereat oil attains su~icient ~luidity wi-thin the oil-bearin~ bed; char~ing a pressurized ~luid into the oil-bearing bed to ~orce oil from the oil--bearing bed into the horizontal and inclined recovery wells toward the recovery gallery; and withdrawing oil Lrom the recover~ ~allery to the ground surface 9 in ~T7hich method, i~ accordance wi-th the invention, the heat-carrier is charged into the oil-bearing bed through the horizontal and inclined recovery wells extending substantial.ly across the dominating direction o~ the highlg permeable zones of the oil-bearing bed, and, ~ollowing t~e hea~ing o~ -the oil-bearing bed to -the required temperature, the heat-carrier supply to the recovery wells is terminated, and the prassuri-zed fluid is charged into the injection wells minimally as-sociated ~ith the highly permeable zones ol the oil~beari~g ., .

be;' 9 to iorce oil ~rom the oil-bearin~ oed into the norizGn~al and inclined recovery wells to~ard the recovery gallery.
The me~thod enables to increase the yield oY the oil--beari~g bed a~d to cut dow~ the period of its developm-3n-t - oviing to the enhanced penetration of -the heaJ-carrier i~to the oil-bearing bed and to the stepped-up ra-te o~ the heating of -the oil bearing bed through the latter's greater volumeg as well as to reduce the resistance to the oil flow encoun-te-red at the near-~ace areas o~ the recovery wells and in the hi~hly permeable zones o~ the oil-bearinO bed, connected therewith, at the inf~ tratio~ o~ oil therein; the method ~urther expandi~g the borders o~ the process o~ ~cing oil ~rom the oil-beari~g bed.
~ he me-thod enables to cut down the costs o~ recovering oil ~rom an oil-bearing bed, owing to the improved pa~tern o~ the layout o~ the recovery wells throughout the bed~
extendi~g as they do across the direc-tion of the hi~hly--permeable zones of the bed, and also owing to t~e bet-ter yeld of these wells and the possibility of reducing -their number, as well as the number of the mine workings w~ich ha~v to be provided tl drill the recovery wells -therefrom.
~ he operating co~ts o~ the ~Jell system are reduced by the lesser number of the recovery wells required, by the reduced ingress o~ sand ~rom t~e oil-bearing bed i~to the recovery wells a~d b~ the minimized even~ualit~ of sand -~2-, plugs ~orming therein and involving addit o~al eflorts of eliminating these plu~s~
~ he method ~urther enables to cut down the cost of ventilating the mine workings, in order to maintain therei~
acceptable atmospheric conditions, and to enhance the working environment and sa~ety o~ the personnel5 owing to the reduced number o~ ventilated mine workings.
It ls expedient that the recovery ~aller~ should be provided in t~e lo~;er part o~ the oil-bearing bed.
This would enable to utilize in the ~ullest de~ree both the phenome~on ol ~orcing-out the oil ~ith the pressuri-zed ~luid, and the phe~omenon o~ gravity ~low O:e oil into the reco-~ery wells~
Alternatively, when oil is recovered from an incoherent oil-bearinæ ~ormation, particularly, one dacreasing i-ts stab-ility upon being heated, it may be pre~erable that the reco-~ery galler.~ sho~ld be provided below the oil-bearing bed7 so that it should be separated ~rom the bed by a low-permeabi-lity stable interbed of rock.
~ his ~Jould enable, when recovering oil ~rom an incohe-rent oil-bearing bed, to reduce the cost o~ providing mine workings~ by making them in rock ~ore suitable for the purposeS and also to reduce the u~desirabla propa~ation o~ heat ~rom thG oil-oearing bed into the ~ine worki~gs.
It is also expedie~t that the heat-carrier should be . .

5~1 .~ chargecl into the oil-bearing bed through the hoiizon~al and inclined recovery wells to hea~ the oil-~earing ~ed until the latter is heated up to a temperature above ~nich the : viscosit~ o~ -the oil at further heating is reduccd but insignifican~l7.
~ his would enable to reduce the consumption o~ -the heat-carrier b~ t~e oil reoove~ process and to enhance the quali-ty of the atmospkere in -the mins.
It is ~urther expedient, if the injection ~ells penet-rate the highly permeable zones o~ t~e oil-bearing bed, ; prior to charging the ~luid into the injection wells, to ~ill the hivhly-permeable zones of the oil-beari~g bed commun-icating ~ith these wells wi-th a plugging composition retaini~g oil-permeabilit~ OL the porous body of the oil-bearinO bed.
~ his enables to enhance the homo~eneit~ of -the oil-bea-.. ring bed~ to conduct the ~orcing-out of oil by the ~luid in an efficient wa~ and to increase the yield of the oil-bea- ring bed.
: It may be also expedient, if one a~d the same recovery of the gallery has some recovery wells penetrating the hir~hly permeable zones o~ the oil-bearing bed and other recovery wells not communicating with these highly permeable zones, to per~orm, si~ultaneously with the char~ing of the heat-carrier into the oil-bearing bed throuOh the horizontal : and inclined recovery wells e~teading substantially across - , ', : ' :' .

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-the dcmi~atin~ dircc-tion ox the hiohly pe.nmeable ~oncs o~ the oil-oearing bedt recoverin~ of oil throuOh ~hose of the horizon-tal and inclined recovery wells which have the mini~um co~rnu~a~ion with the highl~ permea~le zo~es o~ the oil-beari~g bed.
T~is enable6 to recover oil simultaneousl~ with the heating of -the oil-bearin~ bed and to accelerate the neatin~
of the oil-bearing bed itself with partial heatinæ a~d crea-ting i~proved conditions ~or the propagation of the heat : -carrier into the porosi-ty space of the oil-bearing bed.
It is further expedient that at a later stage of the ~ cil recovery from ~he oil-bearing bed the reco~er~ gallery . , .
should be periodically filled with a fluid of a density in excess of that of the oil.
~ his enables to i~crease the total yield of the oil-bearing bed, by creatin~ a non-stationary duty of the performance of the bed, the variation of the direction of in-filtration flo~s i~ the bed and its be-tter capillary ir~pregna-tion.
Furthermore9 i-t enables to reduce the degree of break-through of -t~e heat-carrier into the recovery gallerJ, and thus to irilprove the ~orking enviro~ment and to reduce the ~e~tilation costs.
It is expedient, in the case of an incohere~-t oil-beari~g bed~ ~ith the recovery gallery having been provided under the bed~ prior to -the char~ing of -the fluid -into this in-`~

coi~elent oil-bearing .bed~to wash out wi-th a liquid -through the injec-tion ~ells an area in the lo~er part o,~
the bed, and then to supply into this area matexials forl-2i~
a stable s-tron~ structure permeable ~or the oil~ and to drill asce~dil~ recovery wells into this area.
~ his enables to bri~Y~ nown the cost of drilling asceil-dirlg recovely ~Jells in an incoheren-t oil-bearing bed ~hich is unstable duriLY~ -the hea-ting and under the ac-tion of a flushing liquid, -to reduce the ingress of big quantities o~ sa,nd into the ascendi,Y~ recovery wells a~d into ~e reco-very galler~-~, and to operate these wells e~ficientl~ and without undue complications.
It is likewise e~pedient, in -the case of consolidat-ion of the lower part of the oil-bearing bed throu~rh the injection wells drilled fro~ t,he ground suxface, to provide the recovery gallery below this oil-beari~g bed and to drill there~rom ascendir~ recovery wells into the col~solidated area of the oil-beariY~ bed, and also -to seal the faces of -the injec-tion wells and to charge the fluid throu~h the injection ~lells irlto t~e area of' the oil-~earing bed, di.sposed above the consolidated area of the bed 9 SO as to f'orce oil from the oil-bcarlr~ bed into the ascerlding recovery wells to~vard the recovery gallery.
~ his erlables to use in the most e~ficîent wa~ the phe~omenon of ~orcing oil by -the fluid in cernbination with ~6~

the gravi~y flow o-~ oil~ to minimize -the possi)ility o~ t`ne , luid breaking -through directl~ into t1~e ascendirlg recovery ~e11S drilled ~rom the recovery gallery underlyi~ the oil-beari~r bed arld to reduce ~,he in3ress o~ sa~d into tne ascendin~ recovery wells~
It is further expedient, i~ the ~luid i~iltrates into the ascending recov~ry wells, to close periodically the ascending recovery wells simultaneously with t~e feeding of t~e ~luid into the injection wells, and, ~ollowi~g this closing, to withdraw oil ~rom the area underlying the closing poi~ts.
~ his enables to step up the oil yield o~ the oil-bearing bed, on ~ccount o~ periodic en~orced fluid recoverg, cleating non-stationar~ mode o~ its per~ormance, ~ith periodic with-drawal o~ oil and clsaning o~ the near-~ace areas o~ the ascending recove.ry wells, and also to control -the propagation of the heat-carrier through the oil-beari~æ bed, for the latter -to be heated Gvenly throughout its volume.
iIihe inverltion will be ~urther describ~d in connect~o~
with an embodiment thereo~, with re~e~ence beinæ made to the appended drawings~ wherein;
FIG. 1 is a pla~ view of a system of developirlg a single mini~ element or block o~ an oil-bearing bed~ v~itn mine ~Jorkings and wells indicated;
. 2 is a sectional view taken on line TI~II of ~IG~ 1;
~IG. 3 is a sectional view o~ a sin~le mining bloc~

o~ the oil-bearin~ bed9 with mine workings and ~Jel-s drilled , rom the mine workings within the oil-bearing bed and Lrom the ground sur~ace;
~ IG. 4 i s a sectional view of a single mining ~lock of the oil-bearing bed, with the mine wor~ings therein and wells drilled ~rom the mine Y~orkings below the oil-bearing bed and from t~e ground surface;
~ IG.`5 is a sectional view o~ a single mining block of a fissured oil-beari~g bed being ~eat~d;
~ IG. 6 is a sectional view o~ a single miningr block of a fissurad oil-bearing bed bei~g h~ated, with simultaneous recovery of oil;
~ IG~ 7 is a sectional view of a single mining block of a fissured oil-bearing bed during the oil recovery stage;
~ IG. 8 is a view in plan o~ the sectio~ of ~IG. 7 along line VIII-VIII;
~ IG. 9 is a se¢tional view of a single mining block of an oil~bearing bed, wi-th t~e ~ine workin~s therein and wells drilled ~rom the mine workings underlying the oil-bea-ring bed and ~rom the ground ~ur~aca;
~ IG~ 1~ is a sectional view taken on line X-X o~
~IG. 9 o~ a portio~ o~ a single mining block o~ an oil-bearing bed, with the mi.ne workings underl~ing the oil-bearing bed and wells drilled therefrom;
~ IG. 11 is a sectio~al ~iew of a portion o~ a single mining block, with the mi~e workings underl~ing the oil-bea-ring bed and wells drilled there~rom.

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The herein disclosed method is preferably perXor[~ed~ a.s ~ollows.
~ he entire oil-bearing ~ormation or bed is subdivided into a plurality OL mining elements or blocks 1 (~IG, 1).
A system ol mine workings 2 is provided above the oil-bearing ~ormation or bed 3 (~IG. 2) in low-permeability above--bed rock 4.
Then from ~hese mine e~orkings 2 there are drilled vertical and inclined injection walls 5 for chargi~g a fluid into the oil-beari~g bed ~ practical, e.g, in case of shallowl~J
e~tending oil-bearin~ beds 3, t~e vertical and inclined injection wells 5 are drilled ~rom the ground sur~ace, ~hen a slope 6 and a man ~ay 7 (~IG. 1) are provided into the oil--bearing bed 3, a~d a recovery gallery 8 is excavated wi~hin the oil~bearing bed 3.
The slope 6 and the man way 7 (~IG. 1) are descend-ing mine workings extending toward the area o~ the oil-bcaring bed 3 (~IG. 2) and necessary for the provision o~ the rscover~
gallery 8. Alternatively, the slope 6 and the man wag 7 (FIG, 1) may be vertical. Here and in the disclo.sure to follo~ the expression "the area o~ the oil bearing be~" is used to describe the oil-bearing bed ~ per se and the under-bed rock 9 (~IG. 3) adjoining the bed.
Provided intermediate the slope 6 and the man wa~ 7 (~IG. 1) is a pumping ohamber 10 to accommodate pumps oper-able to raise oil to t~e ground sur~ace~ ~he recovery ~allery ,' 8 is used to clrill there~rom horizontal recovery ~Jells 11 (FIG. 2) and inclined recovery wells 12.
The term "inclined wells 12'~, as used here, is meant to describe both ascending and descending wells.
~ hile providing the mine workings 2 above the oil-bearing bed, the slope 6, the man way 7 (~IG. 1) and the recovery gallery (~IG. 2)~ and while drilling the injectio~
ells 5 and the recovery wells 11, 12, there is conducted a structural analysis o~ the geological ~ormation of the oil--beari~g bed ~, and t~ex~ is determined the direction OL -the highly permeable ~ones o~ this oil-bearing bed; there is also investigaced the relationship between these zones and the injection wells 5, and the recovery wells 11 and 12.
~ he expression "~ighly permeable 30nes o~ the oil-beari~g bed 3" is used here to describe oriented abnormally per-meable zones in the porous body o~ the oil-bearing bed 3, i.e. these ~ones o~ the oil-beari~ bed o~ ~hich the permeabi-lit~ is several times t~at o~ the main body of the oil-beari~g bed,as well as ~issures 13 (~IG. 5).
I~ case of a~ absence i~ t~e oil-beari~$ bed 3 of a sy~tem a~ natural ~issures ~3, or else of ab~ormally pe~eable æones in the porous body of the oil-beari~g bed 3~ man-made fissures are provided therein~ e.g. by conductinO hydraulic :
fracturing o~ the oil-bearing bed 3, e.g. by charging thr~ugh the recovery wells 11 and 12 a liquid with a brakdown agent~

, :

:

under a pressure in excess of -the rock pressure.
~ ollowing the preparation of the oil-bearin~ bed Lor the development, a heat-carrier7 e.g. steam is ~ed through a system o~ pipelines into the horizon-~al recovery wells 11 and inclined wells 12 extending substantially across the dominating direction o~ t~e highly permeable zo~es, e.g.
fissUes 13 of the oil-bearing be~, to heat the latter to a temperature whereat oil acquires su~ficient ~luidity within the oil-bearing bed 3. Instead o~ steam the heat-carrier may be in the ~or~ of warm or hot water, as well as of steam--water mixtures with sur~ace-active age~ts or ~ases. Arrows "A" in the drawings indicate the direction of propagation of the heat-carrier through the oil-beari~g bed.
As a result of the heat-carrier being charOad into the ~orizon-tal recovery wells 11 and inclined recovery wells 12 extending across the dominating direction of the highly permeable zones, e.g. of the~main pattern o~ the fissures 13 of the oil-bearing bed 3, the heat-carrier uni~ormly a~d swi~tly propagates throughout the body o~ the oi~-bearing bed 3. ~hus1 to heat up the oil-bearing bed 37 there is utilized the maximum available surface o~ t~e reoovery wells 11, 12 and of the ~issures 13 o~ the oil-bearing bed 3, which is of a particular importance at the initial sta~e of the de~elopment o~ the oil-bearing bed, when the viscous low--flue~t oil opposes the access of the heat-carrier into ., ' ` ;:`

the po~ous body o~ the oil-bearing bed, and the heat trans~er to the oil-bearin~ bed can be ef~ected practically exclusively owi~g ~o its heat conductivity. ~his enhances ~he opti~um impact of the action of the heat-carrier upon -the oil-bearin~ bed 3, speeds up the heating-up o~ this oil-bearing bed 3 and rapidly reduces the viscosity o~ oil, so that the latter at$ains su~icient ~luidity in the porous body o~ the oil-bearing bed 39 which cu~s down the oil field development time.
The greater sur~ace of the opening-up o~ the oil-~earing bed 3 by the recovery wells 11 and 12 and by the fissures 13 associated and communicating therewith enables to reduce significantl~ the number o~ the wells required ~ox oil recovery, and thus to save the cost of drilling and operating these wells.
~ his also cuts down the volume of the mining work associated with the provision o~ thc mine workings, such as the slope 6 (~IG. 1), man way 7 and recov~xy gallery 8 required for drilling the recovery wells 11 tFIG 2) and 12 ~ he gr~ater sur~ace area o~ t~e opening-up o~ the oil-bearing bed 3 also eliminates the necessity o~ charging the heat-carrier into th~ ~ormation under a ver~ hig~ press-ure9 which helps prevent breakthrough o~ the heat-carrier into the mine workings 2 overlying the oil-bearing bed, into the slope 6 (~IG. 1~ man way 7 and recover~ gallery 8 (~I~. 2) ..,~ , :
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1~ 6 L

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and its ~leeding beyoncl the ar~a of the portion OL the oil-bearing bed 3, which is bein~ developed; and which also improves the working enviro~ment in the mine worki~gs and enhances safe ~Jorking conditions. ~he co~sumption o~ t~e heat-carrier is reduced, too.
The heating of the oil-beari~g bed 3 ~rom 'he recovery wells 11 and 12 enables to bring down considerablY the infiltration resistance to the flow o~ oil from the oil-beari~g bed 3 into the fissures 13 (~qG. 5) and the recovery wells 11 and ~2.
This ~act, in its turn, enables to increass signi~`icant-ly the per day ~ield of the oil-bearing bed, as well as to preve~t t~e ingress of g æ at quantities of sa~d i~to the recovery wells 1~ a~d 12, and thus to preclude e~entual faults in the opera~ion of thesc wells.
Upon the oil-bearing bed 3 having been heated up to a temperature whexeat the oil acquires sufficient fluidi~y withi~ the oil-bearing bed 3, the feed o~ the heat-carrier -into the recover~ wells 11 and 12 is discontinued.
The~ a pressurized ~luid, e.g. warm water is charged i~to the i~aection wells 5 which are minimally associated with the highly permeable zoneæ, e.g. ~issures of the oil-beari~g bed 3, to ~orce oil from this oil-bearing bed 3 into the horizontal recovery wells 11 and i~clined recovery wells ~2 toward the gallery 8.

; 23-~ . .

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~ he direction o~ propagation o~ the ~luid throuOrh the oil-beariL~ bed ~ is indicated i~ the draviings with arrows IGS~ 7 and 8)-~ he direction o~ the ~low o~ oil ~orced from the oil--bearing bed 3 is indicated in the drawings wi.th arrows "C".
From the recovery galler~ 8 oil is li~ted to the ~round sur~ace by pu~ps installed in the pumping chamber 10 (~IG. 1).
~ he charging o~ the ~luid through the injection wells ~ (~IGS. 7 and 8) minimally associated wi~h the ~issures 13 enhances ~he ef~iciency o~ the ~orcing o~ oil ~rom the oil-bearing ~ed into the recovery wells 11 and 12 (~lG. 7) a~d ~teps up the oil yield of the oil-bearing bed ~.
~ his also enables to minimize the eventualit~ of the fluid breakin~r through into the recovery wells 11 and 12, as well as to reduce the amount o~ the fluid re~uired ~or for¢ing oil ~rom the oil-bearin~ bed 3. ~he conditions for the ingress o~ sand ~rom the oil-bearing bed 3 into tke recov~-ry wells 11 and 12 are likewise impaired, thus eliminati~gr eventual ~aults in the performance of these wells.
~ ith oil bein~ ~orced ~rom the oil-bearin~ bed by the ~luid into the horizontal recovery wells 11 and inclined recovery wells 12 o~ which the in~iltratiol~ area is more heated tha~ the rest o~ the zones o~ the formatlon~ so that oil therei~ has the lowes~t ~iscosit~, the oil ~ield of the oil-bearing bed 3 is stepped up, and the productivity .

i;6 1 of the recovery wells 11 and 12 is maintained at ~he maximum.
~ he utilization of the horizontal recover~ wells 11 a~d inclined recovery wells 12 opening up to the maxi~um the highly permeable zones, e.g, ~issures 13 o~ the oil-bearing bed ~or charging the heat-carrier therethrou~h at the bed-heatil~ stage~ and, ~ollowing -the heatinæ up o~ the oil-bearing bed 3, for collecting therein the oil ~orced by the ~luid charged into the injection wells 5 saves the cost of driIling extra wells and providing either e~tra or greater mine workin~s, such as the slope 6 (FIG. 1), man way 7 and recovery gallery 8; it further saves ventil:ation C05tS associated with ventilation o~ greater mine workings, and cuts down the time of the davelopment of the oil-bearing bed ~ (~IG. 7).
~ o utilize to the ~ullest possible degree the phenomenon of gravity flow of oil ~or oil recovery into the recovery wells 11 and 129 simultaneously with the ~orcing o~ oil by the ~luid into the same wolls 11 and 12, in one embodiment of the present inventio~ the slope 6 and the man way 7 (~IG. 1) are provided into the lower part o~ the oil-bearing bed 3 (FIG. 3), and then there is provided in this low~r part o~
the oil-bearing bed 3 the recovery gallery 8 from which the horizontal recovery wells 11 and the inclined recovery wells 12 are drilled.
This enables to step up the producti~ity of the recover~

.

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L

vlells 11 and 12 and to increase the per day ~ield o~ -~he oil--bearing bed 3.
In anot~er embodiment o~ the invention, in the case of recoveri~g oil from an i~coherent oil-bearinO bed 3 becoming unstable when heat~d7 the slope 6 and -the man w~y 7 (~IG. 1) are provided into low-permeability stable roc~
9 underlying the oil-bearing bed 3.
~ hen the recovery gallery 8 is provided so that it is separated f~om ~he incohere~t oil-beari~g bed ~ b~ a loYi-permeability steady interbed 14 (~IG, 4) of the roc~ 9.
~hen ascendi~g recovery wells 15 are drilled from this recovery gallery.
In this case the cost of the provision of the recovery gallery 8 is reduced, the undesirable propa~ratio~ Qf heat ~rom the oil-bearing bed ~ into this recovery gallery 8 bei~g curbed down9 and the ventilation costs being reduced, too.
I~ a preferred embodiment o~ the present invention, the heat-carrier i8 ~ed i~t~ the ~ beari~g bed 3 through the recovery wells 11, 12 a~d 15 until t~e oil-bearing bed 3 is heated up to a temperatu.r3 above which the viscosity ~o~ the oil is practically not reduced by furthex heatin~.
; ~he practical experience o~ -the inventors has proved that various crude oil grades with aif~erent cornpositions have each a definite temperature above which this oil grade does ~ot become more fluid at further heating.

~26-

2~1 If the oil-bearing bed 3 is inadequately hea-ted, i.e.
if it is ~ot heated to re~uce the oil ~iscosity to the ~ecess-ary level, the e~icie~cy o~ the forcing out of oil by the pressurîzed ~luid is affected; howe~er, o~ ~he other ha~d, excessive heating of the oil-bearing bed ~ would not signi~-icantly enhanc~ this ef~iciency and increase the oil yield.
~ he heating of the oil-beari~g bed 3 to the abovamenti-; oned optimum temperature reduces the overall consumption of the heat-carrier by the oil recovery process~ I~ this way excessive heating o~ the oil-bearinO bed 3 is precluded, the atmosphere in the mine workings is improved, and the~
. o~
costs ventilation o~ the mine workings 2 (~IG. 1) above the oil-bearin~ bed 3, o~ the slope 6 and of the man way 8 are reduced.
In another embodiment of the present invention, in the case of the prese~ce i~ the oil-bearing bed (FIG. 5) of a dense network of natural high-permeabilit~ zones, e g.
fissures 13, the injection wells 5 drilled from the mine workings 2 and ~rom the grou~d sur~ace inadvertentl~ penetrate or open up at lea.st some of these ~issures 13.
~herefore, prior to ~orcing oil bg the pressu~ zed fluid into the recovery wells 11, 12 and 15 (~IG. 4) toward the recovery gallery 8, there is charged into those of the inaection wells 5 (~IG. 5), which are communicati~g with the ~issures 13, a plugging composition selected to retain the `:~

~, .
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oil-per~ea~ility o~ the porous body o~ tha oil-bearing bed, e.g. a binder based on a mixture of phenols with vlater, a solvent and a setting agent.
~ he~ into the sa~e inaection wells 5 there is charged a neU~ral liquid, eO~. crude oil, to force the plugging solution ~rom these injection wells 5 into the fissures 13 oP the oil-bearingr bed 3.
And only then the pressurized Lluid is charged into the inj~ction wells 5 to Porcç oil Prom the oil-bearing bed

3 into the recovery wells 11, 12 and 15 (~IG. 4), toward tha recovory galler~ 8.
~ he filling up of the ~issures 13 (FIG. 5) associated with at least some of the injection wells 5 with -the plugging solution enables to level out the homogeneity of the oil-bearing bed 3 as far as its oil-permeabili-ty is concerned~
and to enhance the efficiency o~ the forcing--out o~ oil ~rom this oil-bearing bed 3 by the pressuriæed ~luid. ~his enables to increase the oil yield oP the oil-bearing bed 3, to prev~t ~reakthrou~h o~ the pressurized ~luld via the fissures 13 into the recovery wolls 11~ 12 and 15, and to reduce the amount o~ the pressurized fluid required ~or forci~g out oil.
In another embodiment of` the invention, in a case when the amount of' the ~issures 13 in the oil-bearin~r bed 3 is relativel~ small, and some of the recovery wells 11, 12 and 15 (FIG. 4) do not penetrate these fissures 13 (FIG. 5) of the oil-bearing bed 3,the heat-carrier is~arged into the recovery wells 11, 12 and 15 extenaing ac~oss the direc-tion of the main system o~ the fissures 131 and simultaneously oil is collected from the oil-bearing 4ed 3 through those o~ the recovery wells 11, 12 and 15 which have the minimum degree of communicatio~ or associatio~ with the ~issures 13 (FIG. 6).
~ his enables to recover oil simultaneously ~ith the heating o~ the oil-bearing bed 3, to relieve partly the porous spaoe of the oil-bearing bed 3 from oil, thus offering this space for better propagation of the heat-carrier thereinto and to speed up the heating o~ the oil-bearing bed 3, owing to the greater area of the co~tact of the heat-carrier witi, the oil-baaring bed 3.
~ ollowing t~e heating up o~ the oii-bearing bed to the predetermined temperature, the feed o~ the heat-carrier into the recover~ wells 11 and 12 is discontinued, and the pressurized ~luid is charged into the in~ectio~ well~ 5 to ~orce oil from the oil-bearing bed 3 into the reoovery wells 11 and 12, toward the re¢overy gallery 8.
However, in certain pra¢tical ca:ses, at a later stage of the oil production process the oil-bearing bed 3 becomes partly exhaustsd, and the produotivity of the recovery wells 11 and 12 becomes insufficient.

.
' In this case the recovery gallery 8 (~IG~. 2 and 3) provided within the oil~bearing bed ~ i~ preferably ~illed with a ~luid havil~ a density i~ e~cess o~ that of oil, e,~, with warm water.
~hen a heat carxier under a relatively high pressure, e.g. steam is charged as the pressurized fluid into those ~ o~ the injection wolls 5, which have the minimum commu~ication - or association wi-th the ~issures 13.
This feed of the heat-carrier into the oil-bearing bed 3 is carried out until the latter is heated to a predetermined higher temperature.
~- ~hen the ¢har~ing o~ the heat-carrier into the said injection wells 5 is terminated, warm water is char~ed there-into as the pressurized ~luid, and ~rom th~ rccovery galler~
8 the ~luid, e.g. water is pumped by pumps installed in the pumping chamber 10 (PIG. 1) into the mine workings 2 (~IG. 2) overlying the oil-bearing bed 3 and~ or to the grou~d surface, to charge this fluid once again into the said in~ection wells 5.
; Following the pumping out o~ water ~rom the recovery gallery 8, the opera-tion o~ ~orcing out oil from the oil--bearing bed ~ by the pressurized fluid into the recovery wells 11 and 12 toward the recovery gallery 8 is continued as long as the productivit~ of these wolls 11 and 12 remains at a satis~actory leYelA

-3~-., Z~

Upon the reduction of the productivity of the recovery ~ wells 11 a~d 12 below the said level, the recovery gallery 3 is once a~ai~ ~illed with warm water, and the heat-carrier iB charged into the injection wells 5.
~he abovedescribed pattern o~ ~illing the recovery : gallery 8 with water and pumping water there~rom is repeated periodically, as long as the oil-bearing bed 3 remains adequately heated, and the productivity o~ the recovery wells 11 and 12 rema~ns at the satisfactory level.
~: ~he recurrent filling o~ the recovery gallery 8 with the fluid, e.g. water enables to charge the heat-carri~r at a high pressure through the inje~tion wells 5, and thus .,, to increase the rate and to enhance the ef~iciency of the heating-up of the oil-bearin~ bed 3 and o~ the forcing -out of oil therefrom, while reliably seali~g away the recov-ery wells 11 and 12 and precluding the breakthrouzh of the heat-~arrier, e.g. condensed steam into the recovery -. galler~ 8 and into the mine workinss 2 overlying the oil--bearing bed 3, including the slope 6 ~nd the man way 7 (~IG. 1 In this way the costs of ventilation of the said mine ~:
workings are subs-tantiall~ reduced, and ~he working environ--; me~t and safet~ of t~e personnel are enhanced.
~ he filling up o~ the reco~er~ gallery 8 (FIG. 2) extending within the oil-bearing bed 3 with the fluid, e.g.

: -3~-:

5-~;1 water providcs for a substantial increase in the ~ater-sa-turation o~ the oil-bearing bed 3, o~ing to the water inflo~
through the recovery v~ells 11 and 12 and the fissures 13 associated therewith, and for mor intenfie capillary impreg-nation o~ -the oil-bearing bed 3, while the pumpi~g out o~
this ~luid ~rom the recovery gallery 8 provides for enforced recovery of liquid ~rom the oil-bearing bed 3.
In this manner a non-stationary mode o~ performance of the oil-bearing bed 3 is pro~ided for, with rec~urrent -oscillations o~ the liquid ~low rates and variation of the velocit~ and direction of the infiltration flows~ which enables to involve into the development by the recovery wells 11 and 12 o~ low-permeability intervening portions of the bed 3, its bli~d portions, the lea~t heated portions, and the like.
~ he abovedescribed processes increase the productivity of the recovery wells and cut dow~ tha time of the total oil production ~rom the oil-b~aring bed 30 I~ another embodiment of the present invention, when oil is to be recovered from a~ incoherent oil-bearing bed 3 (~IG. 9), particularly a bed that become~ unstable upon being heated, following the drilling from either the mine workings 2 or from the ground sur~ace R the injection wells 5 into the oil-bearing bed 3 to the bottom thereof, t~e slope 6 and the man way 7 are excavated into the low-permeability rock ~ormation 9 underlyi~g the oil-bearing bed 3.

-32- .

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Then t~e recovery gallery 8 i5 provided under thc oil--bearin~ bed 3 50 that it is sep~rated from the latter by a low-permeability stable interbed ~4 of the rock 9.
Following this, the casings o~ the injection wells 5 are perforated at poi~ts 16 within the lower part of the oil-bearîng bed9 and through the per~orations there i~
charged i~to this incoherent oil-bearing bed 3 under a hydrau-lic ~xactu~ing presæur~, i.e. a preasure in excess o~ tho rock pressure, a cold liquid, e.g. water containing an expan-ding agent, e.g. ~and.
~ ollowin~ the hydraulic ~ractuxing of -the oil-bearing bed 3 bet~een the injection ~lls 5, cold liquid is pu~p~d through the latter to wash away an area in the lower part of the oil-bearing bed 3.
Ih~n materials are ~ed i~to this washed-awa~ part of tho oil~b~aring bed, e~g. a binding a~ent based on a mixture o~ phenols with water, a sol~ent and a se-ttin~ agent, to form a stable stronæ structure 17 of adequate oil permeability.
~ o enhance t~e permeability o~ this consolidated area, the binding or consolidating agent is preferably supplied into the wash0d away area o~ the oil-beari~g bed together with granulated materials, and, also pre~erably, the bindi~g or consolidati~ agent is ~orced through into the peripheral por~ions of the washed awa~ area being consolidated by chargi~g into the injec-~ion wells 5 a liquid which is neutral with respect of this agent, e.g. oil.
- ~ollowing the consolidation o~ this area of the incoherent -. oil-bearin~ bed 3, ascending recovery wel~s 15 are drilled;~ from the recovery gallery 8 into t~is consolidated area 17 o~ the oil-bearing bed 3.
~ hen the heat-carrier is charged through these recovery w~lls 15 into the oil-bearing bed ~ until at least the bottom part o~ the latter i~ heate~ up to a temperature ~Jhere-at oil acquires the nece~sary ~luidity within the oil-bearing . bed 3.
With t.his attained, the charging of the heat-carrier through the reaovery wells 15 is discontinued, and the press-urized ~luid, e.g. steam is charged into the oil-bearing ` bed 3 throug~ the injectia~ wells 5 to ~or¢e oil into the reaovery wells 15 toward ~he recovery gallery 8.
~ he consolidatio~ o~ the inaohercnt oil-bearing bed 3 .~ through the injection wells 5 drilled either ~rom the ground sur~ace or from the mine workings 2 overlying the oil-bearing bed ~, and the subse~uent drilling o~ the recovery wells 15 into the consolidated and adequately permeable area 17 enable to preolude complicabions otherwi~a associated with the drilling o~ the asoanding recover~ wells 15 in the inooh-erenb oil-bearing bed 3, e.g. bhe in~low from the bed 3 o~ bi~ quantities o~ sand on a¢cou~b o~ b~e action upon this bed ~ with the drilling tools and the drill mud. ~hus, :

~ .

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the cost of drilling the ascending recovery wells 15 is reduced.
Furthermore, the conditio~s o~ cxeating an infiltratio~
zones o~ the as¢e~di~g reoovery wells ~5 in the incoherent oil-bearing bed ~ are signi~ioa~ly facilitated; the compl~ca-tions involved in the oreation of such zones are precluded, and co~ditions are created for supplying into the oil-bearîng bed 3 greater volumes of the required filtratio~ materials, including gra~ulated material~.
There ~s provided a possibility o~ cr~ating an infil~ra-tio~ ZOD~ of a great area ad~acent to t~e ascending recovery wells 15 with the use of granulated materials, which enables to impiove its permeability and to enhance the productivity of the recover~ells 15~
~ he complicatio~ associated with the operatin~ of the ascending recovar~ells ars also mi~imized, owing ~o the mi~imized ing~ess o~ great ~ua~titie8 o~ sand ~rom the incoherent oil bearing bed 3 into these wells, which also increase~ the productivity o~ these wells 15~
~ e utilizatio~ o~ a large volume of granulated material ~ox consolidation o~ the i~iltration zone o~ the ascending recovery wells 15 in the lower portion of the incoherent oil--bearing bed 3 provides for better drainin~ coverage by the re¢overy wells 15 of ~ greater area o* the oil-beari~g bed 3 a~d steps up the productivity o~ the wells.

.

. ' ' Ulti~ately, this enables to reduce the volume and number o~ ~he mine wor~ings whi¢h are to be provided, i.e. o~ ~e -slope 6 ~FIG. 1), of the man way 7 a~d o-f the recovery æallery or galleries 8, owing to the smaller number of t~e recovery wells (~IG. 9) required ~or the development o~ the oil-bearing bed 3.
- In still another embodime~t o~ the present invention, to enhance the ef~iciency of forcing out oil by the pressurized ~luid i~o the recov~r~ wQlls 15 t~ward ~he recoveIy gallery 8 and to utilize to the ~ullest degree the phenomenon o~
gravity flow of oil into the reco~ery wells 15, prior to charging the pressurized ~luid into tb~ injection wells 5 to force out oil from the incoherent oil-beari~ bed 39 the faces of the injectio~ wells 5 are sealed, e.g. with aid of packers 18. ~hen perforations 19 are made through the re~pective ca-sing5 of the injection well~ 5 centrally of the oil-bearing bed 3, and the ~eat-¢arrier is charged into the i~jection wells 5 as the pressurized fluid, e.g. steam, to ~orce oil into th~
ascending recovary wells 15 toward the reco~ery gallery 8.
~ his enables to enhance the efficiency of the utiliza-tio~ o~ ~he pressuri~ed ~luid, e.g~ steam as both the a~ent for forci~g -out oil and as the heat-carrier for heati~g the oil--bearing bed, and t~us to reduce the consumption of this presswrized fluid.
~ he sealing of the faces o:~ the injectio~:L wells 5 with S~ i the packers 18 and the charging of the pressurized ~luid into the central part of the incoherent oil-bearing bed 3 prevents hreakthrough o~ thi~ ~luid, e.g. o~ con~ensed ~team, into the ascending recovery well~ 15 and in~o the mine workings 2 overlying the oil-bearing bed 3, the slope - 6, the man way 7 and the reoovery gallery 8, which improves - the state o~ the atmosphere in the mine and reduces the ventîlation costs.
~ he charging of the pressurized ~lu~d into the centra~
part of the inooherent oil-bearing bed 3 also prevents the ingr~ss of great quantities of sa~d i~to the ascending reaovery wells 15.
As the pressurized fluid, e.g. steam is charged through ., w the injeation ells 5 i~to $he incoherent oil-bearin~ bed to force oil therefrom into the asoending recovery wells 15 toward the reoovery gallery 8, the portion of the in-ooher0nt oil-bearing bed 3 intermediate the well~ 5 and 15 is under the aotion of the most pronou~ced pressure drop ~; (or, as it i8 sometimes said, under the grea~e~t depression).
011 within thi ~ortio~ of the oil-bearing bed 3 is under the most pro~ounced action o~ the pressurized fluid e.g of steam, and is the ~irst to be forced out into the recovery wells 15, i.e. this portîon i8 the ~irst to become ; highly permeable ~or the pressurized ~luid, e.g. steam.
Co~de~sed steam becomes capable of breaking through , ~

into the ascending recovery wells 15, a~ecting thereby the state o~ the mine atmosphere a~d do~ng ~o useful work o~
~orai~g oil from the oil-bearing bed 3. Besides, the break-through of the pressurîzed ~luid directly in-to the recovery wells 15 sharply incre~ses the quantity of sand carried into these v~ells and clogs their infiltration zone with sand.
In this case, according to a ~urther embodiment o~ the present i~vention, simultanoously with the chargi~g o~ the pressurized ~luid into the inaestion wells 5, the ascending recovery wells 15 (~IG. 10) arc periodically closed of~, e.g. with a gate 20. ~ollowing their closing~of~, oil is pumped from a zone underlying -the closing-of~ point9 i.e.
from th~ recovery well 15 below the gate 20, anl from th~
oil-Gollecting ma~i~old 21 through the recovery gallery 8 to the ground suI~ace.
~ he period between the opening and closing of the recovery well 15, during which oil is recovered ~rom the open well 15, is set to aorrespond to the satis~actory producti vity o~ the well 15 and to the tolarable co~ ent o~ the ~luid, e.g. o~ condensed steam in its product.
As soo~ as the said parameters fail to meet the pre-determined standards, the ascending recovery well 15 is closed o~ with the ~a-to 20, and recovery o~ oil therefrom is discontinued ~or the preassessed period o~ restoration o~ these parameters to th~ preset norm, during which period oil is recovered ~rom the ad~acent open recovery well~ 15.

With the abovementioned period having lapsed, the said ascending recovery well 15 i8 reopened, and the liquid having in the meantime acoumulated in this reco~ery well 15 ~low~ at a high rat~ into the empty oil collector 21, c~using a pressure drop at the face o~ the well 15.
~ he periodi¢ closi~ of the ascending reco~ery vJalls 15 enables to vary the direc~ion o~ infiltration ~lows o~ the fluid in the incoherent oil--bearing bed 3 and to increase the oil yield ~her~o~; and whe~ the heat-carrier is charged through the in~ection wQll~ 5 as the pressuriz~d ~luid ~r ~orci~g ~u~ oil, there ls ensured the regulation of the thermal action upo~ the incoherent oil-boari~g bed b~ maintaining the uniformity o~ the propagation o~ the heat-carrier thr~u~hout the volume o~ the bed; moreover, the conditions ~or the heat-carrier breaking through into the ascending recovery wells 15 are minimized.
~ hi~ decreases the ~aluc o~ the consumption o~ the heat-carrier per weight unit o~ recovcr~d oil and enhan¢es the state of the atraosphero in the mine.
~ he periodic closing o~ the a~cending recov~ry wells 15, followed by withdrawal o~ oil from the zone underlying the closing spot through the recovery gallery 8 to the ground suI~ace also enables, and that without additional cost~ to periodically create depressions acting upon the oil-bearing bed and to clear the ~ear-face areas o~ the ascendin~s recovery wells 1 5.

.

~ his enables to st~p up the productivi~ v~ the recovery wells 15.
~ he charging o~ the heat-oarrier through the a~cending reaovery wells 15 into the oil-bearing bed 3 at the stage o~ heating the latter to a temperature whereat oil acquire~
. ~ suf~i¢ient fluidity in the oil-bearing bed ~ i~ preferabl~
e~fected via tubes 22 (~IG. 11) accommodated within the casings 2~ o~ the a~cending recovery well~ 15.
: ~he about-tube space intermediate the casing 23 and ~ the tubes 22 is sealed away at the mouth of the well with : ~ a plugging ~olution, e.g. one oontaining a liquid hydrooarbon and a pulverulent mineral weighing agent, such as finely ground ~ilica with particle size short o~ 1 micron.
~ he said solution i9 to have a high boiling poi~t, to prevent evaporati~ thereo~ in the outside-~ube space, as it i~ heated by the heat-carrier.
~ he solution, which aan bo an~ suitable known per se one, is to be adequately ~table, proo~ against disintegration ; within a preset t~me, ~u~iciently de~se and Yi~CoUs at elevated temperatures, o~ low he~t conductivit~ and o~ fine sealing properties.
; ~he sealing away of the mouths of the ascendin~ rQcov~ry ~ wells ~5 at the ~ta~e of thQ char~ing of the heat carrier at .,.~ ...
an elevated temperature into the oil-bearing ~ormation enable~
to prevent the brea~through o~ the heat-carrier into the recovery gallery 8 and to reduce the e.manation o~ heat into the reco~er~ gallcry 8 o~ account o~ heat co~ductivity. ~his en~ances th~ state o~ the mining atmosphere and reduce~ the ventilation costs.
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Claims (25)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of thermal-mine recovery of oil and fluent bitumens, comprising: providing a system of mine working overlying an oil-bearing formation; drilling from said mine working and from the ground surface a plurality of injection wells adapted for charging a pressurized fluid therethrough into the oil-bearing formation; providing a slope and a man way in the area of the oil-bearing formation, where the provision of a recovery gallery is envisaged; providing the recovery gallery in this area of the oil-bearing formation; drilling from said recovery gallery a system of horizontal and inclined oil recovery wells which are separate from the injection wells;
charging a heat-carrier into the recovery wells extending sub-stantially across the dominating direction of the highly permeable zones of the oil-bearing formation, for uniform distribution thereof throughout the volume of the oil-bearing formation and for heating the latter to a temperature at which the oil acquires sufficient fluidity within the oil-bearing formation;
terminating the charging of the heat-carrier into said re-covery wells upon the oil-bearing formation having attained the said temperature; charging a pressurized fluid into the injection wells which are separate from the recovery wells, and minimally associated with the highly permeable zones of the oil-bearing formation, to thereby directly supply the pressurized fluid through the injection well into and to force oil from the oil-bearing formation into said horizontal and inclined recovery wells, toward said recovery gallery; and withdrawing oil from said recovery gallery to the ground surface.

2. A method of claim 1, wherein said recovery gallery is provided in the lower part of the oil-bearing formation.

3. A method of claim 1, wherein said recovery gallery is provided below the oil-bearing formation, to be separated therefrom by a low-permeability stable rock interbed.

4. A method of claim 1, wherein the heat-carrier is charged into the oil-bearing formation through the horizontal and inclined recovery wells to heat up the oil-bearing formation until the latter is heated to a temperature above which the viscosity of the oil decreases but insignificantly at subsequent heating.

5. A method of claim 1, wherein, prior to charging the pressurized fluid through the injection wells, the highly permeable zones of the oil-bearing formation communicating with these injection wells are filled with a plugging composition retaining oil permeability of the porous body of the oil-bearing formation.

6. A method of claim 1, wherein, simultaneously with the charging of the heat-carrier into the oil-bearing formation through the horizontal and inclined recovery wells extending substantially across the dominating direction of the highly permeable zones of the oil-bearing formation, oil is being collected through those of the horizontal and inclined recovery wells, which have minimal communication with the highly permeable zones of the oil-bearing formation.

7. A method of Claim 1, wherein at a later stage of the oil recovery from the oil-bearing formation the recovery gallery is periodically filled with a fluid of a density in excess of that of the oil.

8. A method of Claim 1, wherein, prior to charging the pressurized fluid into the incoherent oil-bearing formation, an area is washed away with a liquid in the lower part of this formation, into which area materials are supplied to form a stable oil-permeable structure, whereafter ascending recovery wells are drilled into this consolidated area of the oil-bearing formation.

9. A method of Claim 8, wherein the faces of the injection wells are sealed, and the pressurized fluid is charged through the injection wells into the area of the oil-bearing formation, overlying the said consolidated area thereof, to force oil from the oil-bearing formation into the ascending recovery wells toward the recovery gallery.

10. A method of Claim 8, wherein, simultaneously with the charging of the pressurized fluid into the injection wells, the ascending recovery wells are periodically closed, and following this closing, oil is recovered from the area underlying the closing points.

11. A method of Claim 2, wherein, the heat-carrier is charged into the oil-bearing bed through the horizontal and inclined recovery wells to heat the oil-bearing bed until the latter is heated up to a temperature above which the visco-sity of the oil at further heating is reduced but insignificantly

12. A method of Claim 11 wherein, prior to charging the fluid into the injection wells, the highly permeable zones of the oil-bearing bed communicating with these wells are filled with a plugging composition retaining oil-permeability of the porous body of the oil-bearing bed.

13. A method of Claim 11, wherein, simultaneously with the charging of the heat-carrier into the oil-bearing bed through the horizontal and inclined recovery wells extending substantial-ly across the dominating direction of the highly permeable zones of the oil-bearing bed, oil is recovered through these of the horizontal and inclined recovery wells which have the minimum communication with the highly permeable zones of the oil-bearing bed.

14. A method of Claim 11, wherein, at a later stage of the oil recovery from the oil-bearing bed the recovery gallery is periodically filled with a fluid of a density in excess of that of the oil bed.

15. A method of Claim 3, wherein, the heat-carrier is charged into the oil-bearing bed through the horizontal and inclined recovery wells to heat the oil-bearing bed until the latter is heated up to a temperature above which the viscosi-ty of the oil at further heating is reduced but insignificantly.

16. A method of Claim 15, wherein prior to charging the fluid into the injection wells, the highly permeable zones of the oil-bearing bed communicating with these wells are filled with a plugging composition retaining oil-permeability of the porous body of the oil-bearing bed.

17. A method of Claim 15, wherein, simultaneously with the charging of the heat-carrier into the oil-bearing bed through the horizontal and inclined recovery wells extending substantially across the dominating direction of the highly permeable zones of the oil bearing bed, oil is recovered through those of the horizontal and inclined recovery wells which have the minimum communication with the highly permeable zones of the oil-bearing bed.

18. A method of Claim 15, wherein, prior to the charging of the pressurized fluid into an incoherent oil-bearing bed an area in the lower part thereof is washed out with a liquid through the injection wells, whereupon said area is supplied with materials forming a stable oil-permeable structure and ascending recovery wells are drilled into this consolidated area of the oil-bearing bed.

19. A method of Claim 4, wherein, prior to charging the fluid into the injection wells, the highly permeable zones of the oil-bearing bed communication with the wells are ed with a plugging composition retaining oil-permeability of the porous body of the oil bearing bed.

20. A method of Claim 19, wherein simultaneously with the charging of the heat-carrier into the oil-bearing bed through the horizontal and inclined recovery wells extending substantially across the dominating direction of the highly permeable zones of the oil-bearing bed, oil is recovered through those of the horizontal and inclined recovery wells which have the minimum communication with the highly permeable zones of the oil-bearing bed.

21. A method of Claim 19 wherein, at a later stage of the oil recovery from the oil-bearing bed the recovery gallery is periodically filled with a fluid of a density in excess of that of the oil.

22. A method of Claim 19, wherein prior to the charging of the pressurized fluid into an incoherent oil-bearing bed an area in the lower part thereof is washed out with a liquid through the injection wells, whereupon said area is supplied with materials forming a stable oil-permeable structure and ascending recovery wells are drilled into this consolidated area of the oil-bearing bed.

23. A method of Claim 5, wherein simultaneously with the charging of the heat-carrier into the oil-bearing bed through the horizontal and inclined recovery wells extending substantially across the dominating direction of the highly permeable zones of the oil-bearing bed, oil is recovered through those of the horizontal and inclined recovery wells which have the minimum communication with the highly permeable zones of the oil-bearing bed.

24. A method of Claim 23, wherein, at a later stage of the oil recovery from the oil-bearing bed the recovery galle ry is periodically filled with a fluid of a density in excess of that of the oil.

25. A method of Claim 23, wherein prior to the charging of the pressurized fluid into an incoherent oil-bearing bed an area in the lower part thereof is washed out with a liquid through the injection wells, whereupon said area is supplied with materials forming a stable oil-permeable structure and ascending recovery wells are drilled into this consolidated area of the oil-bearing bed.