CA1167374A - Method of mining an oil deposit - Google Patents
Method of mining an oil depositInfo
- Publication number
- CA1167374A CA1167374A CA000368205A CA368205A CA1167374A CA 1167374 A CA1167374 A CA 1167374A CA 000368205 A CA000368205 A CA 000368205A CA 368205 A CA368205 A CA 368205A CA 1167374 A CA1167374 A CA 1167374A
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- Prior art keywords
- oil
- recovery
- wells
- inlet
- bed
- Prior art date
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Abstract
Abstract of the Disclosure A method of mining an oil deposit, wherein a plurality of underground workings with inlet and recovery galleries are provided in an oil-bearing bed. From the inlet galleries in-let wells are drilled, and from the recovery galleries - re-covery wells. A heat carrier is supplied through the recovery wells to the oil-bearing bed and oil is extracted from the re-covery wells. In so doing, each inlet gallery is arranged in the bed between two recovery galleries and near the faces of the recovery wells, while the inlet and recovery wells in the oil-bearing bed portions between the inlet and recovery gall-eries are drilled towards each other such that they should al-ternate to envelop the oil-bearing bed in a uniform network of wells.
Description
'73'~ ~
~THOD OF ~INING AN OI~ DEPOSIT
The present invention relates to development of oil fields and, more particularl~, it relates to a method of ther-mal-mining production of oil and can be used in the ?etroleum industry.
This invention can be used most efficiently in the de-velopment of oil fields characterized by ~i~hly viscous oils and fluid asphalts.
The inven~ion can also be used for developing oil de-~osits with depleted reservoir energy.
At present, such deposits cannot be efficiently developed b~7 the conventional method wherein oil production is accom~lish ed with the aid of wells drilled from the ground surface. The resulting recovery is rather low.
Rnown in the art for developing oil fields with highly viscous oils and ~luid asphalts is a mining method of oil ~ro-duction without lifting oil-bearing rock to the earth's sur-face (cf., A.Ya. Krems et al., Shahtnaiya razrabotka neftianyh mestorozhdenii - ~he Mining of Oil Deposits, Gostoptehizdat Publishers, ~oscow, 1955).
Said prior art method comprises dr~ving, above the roof of the oil-bearing bed, a system of underground workings in-cluding fringe drifts with drill chambers. ~rom the drill cham-bers, inclined and straight wells are drilled whose denth de-pends on the thickness of the oil-bearing bed and the distance from its roof to the drill chambers. After drilling the wells, oil is reco~ered therefrom by the flowing method and then by air-lift.
','~
~ .
73'~1 -- 2 _ Wrhen employing the flowing method, oil is lifted from the oil-bearing bed throu~h the wells to the drill chambers by res~rvoir pressure; in the case of air-lift, compressed air is injected via pipes placed in the well. From the drill cham-bers, oil is delivered via underground workin~s to central un-derground oil collectors from ~hich it is pumped~ follo~?ing primary preparation and ~reheat, into tanks located on the ground surface.
This method helps increase the recovery by a factor of three and above as com~ared with the develo~ment by means of wells drilled from the earth's surface. However, the absol-ute value of recover~ amounts to only about 6~.
J.ow recovery caused a need to employ mining methods of oil production, which provide for ?hysically affectin~ an oil-bearing bed and the oil contained in the latter.
There is known in the art a method of thermal-minin~ ~ro-duction of oil involving the ex~osure of the bed to the effect of steam and heat (cf., V.N. Ihlishakov et al., O~yt primeneniya teplovyh metodov pri shahtnoi razrabotke mestorozhdenii vyso-koviazkih neftei - On the Use of Thermal Methods upon ~ining ~ighly Viscous Oil Deposits, in ~Teftianoye hozyiaistvo -Journal of Petroleum Industry, No~ 10, 197~, pp. 31-35).
Said prior art method ?rovides for driving above the oil-bearing bed a plurality of underground workings including shafts~ shaft workings, drifts and drill chambersO
From the drill chambers located in the drifts, straight and inclined inlet and recovery wells are drilled. A heat car-rier (steam) is supplied to the oil-bearing bed via inlet ~ i'7,3'79~
wells, which drives oil from the inlet wells to the recovery wells. ~rom the face of the recovery wells, oil is air-lifted to the drill chambers.
Said ~rior art method suffers from the sandin~ up of the recovery wells o?erating by the air-lift method and of the in-let wells. The recovery and inlet wells are clog~ed with sand from the bed.
In addition, the air-lift techni~ue of oil production calls for equi~ping the wells with special ripes or devices for closing and opening the supply of air, when reauired, whi-le considerable amounts of air are required for the delivery of liquid from the wells.
Said prior art method suffers from a low efficiency of the process of thermal~mining production of oil due to consid-erable heat losses through well walls into "barren", oil-free rock, as well as to large amount of drilling to be done in such rock.
According to still another prior art method of oil min-ing (cf., U.S. Patent No. 1,634,235), wells are drilled from underground ~workings located below the oil-bearing bed, and oil is extracted from shallow wells drilled from the bottom upwards. The underground workings are in this case arranged radially from the central shaft over the mining field area.
~ his ?rior art method ~rovides for extraction of oil from the bed by gravity while the face zone of the bed is heated by wa~ of supplying steam to the well face via pipes located in the wells.
Said method suffers from non-uniform arrangement of un-derground workings and wells over the mine field area. Mine 73~}4 field portions adjoining the shaft are developed with the aid of a dense network of wells. Bed portions remote from the shaft are developed with the aid of a s~arse network of wells.
Such an arrangement of wells resul~s in non-uniform mining of oil reserves.
~ here is further known a mining method of oil production (cf., U.~. Patent No. 1,520,737), according to which a vertic-al skaft is driven through the oil-bearing bed below which a drill chamber is arranged from which inclined and ascending wells are drilled in a radial direction.
A heat carrier ~steam) is su~plied to the oil-bearing bed through said wells via pipes having a diameter smaller than that of the well. Ileated oil ~lo~lJs down into the drill cham-ber after which it is ~umped up to the ground surface.
Although said prior art method makes for a si~nler pro-cess of oil recovery and an increased recovery, the bed por-tion under development is limited by the nossibilities of drilli~ the inclined wells or, to be more Drecise, by their length. Therefore, a limited bed ~ortion is to be provided with an individual shaft built from the earth's surface. This affects considerably the economic ~erformance of the latter ~rior art method.
Yet another mining method of developing an oil de~osit, known in the art, involves the heating of oil-bearing bed by ~eriodic injection of steam from underground workings located above a recovery gallery, via system of inlet wells.
~ ithout discontinuing the injection of steam, fluid such as oil and water is periodically extracted via recovery wells drilled from the recovery gallery located in the bottom ~or-l~tj~73'7 tion of the oil-bearing bed. This is followed by periodic injection of hot and then cold water, v~hile continuing the ex-traction of fluid via recovery wells.
This latter prior art method, regarded by the inventors as prototype of the method according to the present invention, is accom~lished in the form of either a two-horizon system or a two-stage system.
Both systems suffer from a non-uniform coverage of the oil-bearing bed by the displacement arocess and, as a result, from low recovery.
In the case of the two-horizon s~stem, large amounts of heat are lost to overlying rock through the walls of inlet wells, which affects the bed-heating efficiency.
In the case of the two-stage system, the bed-heating ef-ficiency is reduced considerably because of non-uniformity of thermal effect upon the oil-bearing bed, as a result of which the peripheral zones of the area under development are heated slowly and oil fails to assume desired fluidity, this leading to lower recovery.
It is the primary object of the present invention to de-velop a method of mining an oil deposit that would help in-crease the current oil production and the rate of oil extract-ion from the de~osit.
It is another object of this invention to develop a met-hod of mining an oil deposit that would help increase the ef-ficiency of thermal effect upon the bed.
It is still another object of the present invention to deveop a method of ~ining an oil deposit that would help re-73 y~
duce the amount of drilling to be done in "barren", oilfreerock.
Said and other objects of the present invention are ac-complished in the herein disclosed method of mining an oil deposit, which comprises:
- arran~ing a plurality of underground workings and re-covery galleries;
- drilling recovery wells in rows from said recovery ~Galleries;
- arranging inlet galleries, each of them in the bed bet-ween two recovery galleries near the faces of said recovery wells;
- drilling inlet wells from said inlet galleries towards said recovery wells such that said inlet and recovery wells should alternate in the oil-bearing bed portions between said inlet and recovery galleries to envelo~ the bed in a uniform networ~ of wells;
- force-feeding a heat carrier to the oil-bearing bed through said inlet ~ells for heating the bed to a temperature at which oil assumes desired fluidity in the latter and for dis~lacing oil to said recovery wells;
- extracting oil from the recovery wells to the recovery galleries; and - delivering oil from the recovery galleries via under-ground wcrkings to the ground surface.
The im~rovement of the method according to the present invention consists in that the inlet galle~ is arranged near the faces of the recoveFy wells, while ~he inlet and recovery y~
wells in the oil-bearing bed portion between the inlet and re-covery galleries are drilled towards each other such that they should envelop the bed in a uniform network of wells.
An increase of current oil ~roduction and of the rate of oil extraction from the oil-bearing bed is attained as a re-sult of heating the oil-bearin~ bed and oil contained in the latter and, consequently, as a result of reducing the oil vis-cosity, expanding oil and increasing reservoir ?ressure. Thanks to a better coverage of the bed by the ~rocess of oil displace-ment by the heat carrier and a more uniform heating of the bed, an increase in recovery is attained.
An increased efficiency of the bed heating process is attained as a result of reducing heat losses through the walls of inlet wells which are drilled in the oil-bearing bed, as well as owing to additional heating of the bed upon the in-flux of heated oil via shaft of the recovery well through less heated ~ortions of the bed.
The efficiency of the oil production process is attained owiDg to an increased recovery and higher rates of develo?-ing oil de~osits, as ~ell as owing to a manifold, sometimes complete, reduction of the amount of well drilling in "barren", oil-free rock.
The herein disclosed method provides for the maximum pos-sible degree of bed drainage by means of horizontal, flat-dipping and flat-raise wells which extend over the oil-bear-ing bed through dozens and hundreds of meters to interconnect its inhomogeneous zones, various channels, cracks and caverns and to increase the degree of bed completion.
J ~ti~73-~
The method of the invention further provides for ensur-in~, along ~ith the oil displacement mode, conditions requir-ed for a display of ~ravi-ty flow of oil, as well as the maxim-um possible simplification of the conditions of w211 o~eration It is exredient that in oil-bearing beds whose to~ ~or-tion is made u~ of poorly cemented loose rock or ~arkedly fis-sured rock, with hi~h-pressure water-bearing beds located be-low such oil-bearing beds, the inlet and recovery galleries should be located in the bottom portion of the oil-bearin~ bed ,'ith the inlet and recovery galleries located in the bot-tom Dortion of the bed, the inlet and recovery wells are fully located in ~he oil-bearing bed. Naturally, this hel~s fully eli-minate heat losses to "barren" rock through well walls due to heat conductivity. All of the heat is consumed for heating the oil-bearing bed.
It is further exnedient that in oil-bearing beds made u~
of ~oorly cemented and loose rock, with beds of stable and hard rock located therebelow, the inlet and recovery galleries should be located below the oil-bearin~ bed.
The arrangement of the recovery galleries below the oil--bearing bed makes for improved operating conditions of raise wells thanks to a reduced possibility of sand ~lugging. Under-ground air in the inlet and recovery galleries is im~roved owing to the location of said galleries in oilfree roc~.
Since the tops of the inlet and recovery wells are in a water-bearing bed, favorable conditions exist for their seal-ing. Shaft portions of wells drilled in water-bearing bed pre-sent, as a rule, an insignifacant fraction of the well lergth.
l~ti';''3'~'4 _ 9 ~
In this case, heat losses to "barren" rock are negligible owing, first, to a reliable insulation of the wells in the to~
portion and, second, to the tendency of heat to move upwards, i.e., to the zone of oil extraction from the derosit.
The present invention will be better understood u~on con-sidering the following detailed description of an exem?lary embodiment thereof, with due reference to the accomDanying drawings in which:
Figure 1 shows the variation of the mean tem?erature of the oil-bearing bed over the length of a horizontal inlet well;
Figure 2 is a plan view of a portion of oil-bearing bed under develo?ment with inlet and recovery wells and under-ground workings (underground workings and wells are conven-tionally superposed in a single horizontal plane);
Figure 3 is a section taken along the line III-III of Fig. 2 for the case when the inlet and recovery galleries are located in the bottom portion of the oil-bearing bed; ard Fi~ure 4 is a section taken along the line III-III of Fig. 2 for the case ~vhen the inlet and recovery galleries are located below the oil-bearing bed.
~ he herein disclosed method is realized in the follow-ing manner.
A plurality of underground workings is set up, including two shafts, namely, a winding shaft 1 (Figs. 2, 3) and a ven-tilating shaft 2, a mine yard 3 (Fig. 3), shaft workings which house a locomotive barn, a pumping station, storages etc. (not shown in the drawings), drifts 4, inclined workings 1 g ~;7374 5 and 6 (Figs. 2 and 3). The drifts 4 are driven sbove the roof of an oil-bearing bed 7 (~i~. 3) and inclined to the horizon at an angle of from 1 to 3.
The inclined Yorkings 5 and 6 are driven from the drifts 4 (Figs. 2 and 3) to the bottom portion of the bed or below the latter, where at least one inlet gallery 8 and recovery gallery 9 are set up.
The inlet galleries 8 are located near the faces of re-cover~7 wells (11). Both the inlet and ~ecoveI~ galleries (8 and 9, res~ectively) ma~ be rectilinear (as shown in ~ig. 2) or curvilinear, depending on the shape of the area under de-velopment.
Upon delivery of steam via horizontal or flat-raise inlet wells 10, pressure losses over the well length cause a nressu-re drop between the well top and face. At the same time, there is observed a tem~erature drop over the length of the inlet wells 10, caused by the transfer of heat to the oil-bearing bed 7 saturated Yiith liquids.
Since low delivery r!ressures are emplo~ed in oil ~ells, low-temperature steam arrives to the tops of the inlet wells 10, while it is practically a condensate (hot water) that ar-rives to the well faces. Curve A in ~i~. 1 indicates the mean temperature of the bed over the length of a horizontal well in one of the actual portions of the oil well.
~ n the bed zone adjoining the top portion of the inlet well 10 (~igs. 2 and 3), heating is carried out owing to heat conductivity inasmuch as this part of the well is cased witk a string. In the zone of the oil-bearing bed 7 (~ig~ 3) adjoin-3~
ing the face portion of the inlet well 10, the bed is heatedowing to convection heat transfer. In the face portion of said well, the pressure and tem~erature are rather low and have no considerable effect u?on the heating of the oil-bearin~ bed 7.
When delivering steam at low pressures, as is often the case, the heating of the oil-bearing bed 7 is ~ainl~ accomplish-ed owing to ~eat conductivity from the shafts of the horizontal inlet wells 10.
As seen from the chart (curve A) showing the well len~th dependence of the mean temperature (~ig. 1~, the hi~hest tem-perature is observed in the top portion of the well. ~his en-tails an increase ol the temDerature of the walls of the gal-lery 8 (~igs. 2 and 3) from which the wells are ~rilled, as well as an increased release of heat to underground air. If both inlet and recovery wells are located in one and the same gallery, this leads to aegravation of the workin~ conditions for the personnel engaged in the recovery of oil from the re-covery wells.
An increase of the amount of air used for airing caus-es large heat losses from the bed which, in turn, affects ad-versely the heatin~ efficiency and the heat balance of the rrocess of thermally influencing the oilbearln~ bed 7 (~ig. 3).
In order to eliminate the afore-described disadvantages, the inlet and recovery galleries (8 and 9, res~ectively) are located in the bottom portion of the oil-bearin~ bed 7 or be-low the latter, the inlet galleries 8 bein~ located near the faces of the bottom row of the recovery wells 11.
Oil assuming desired fluidity in the portions adjoining .the tops of the inlet wells 10 arrives to the faces of the ``` l.~ti'~3'~
recovery wells 11 and then, via shafts of the recovery wells 11, to the recovery gallery 9. The heat received by oil in said zone is partly transferred to the bed upon oil ~,ovement towards the recovery gallery 9. This r.a~es for the heating of the oilbearin~, bed 7 over the entire volume thereof thanks to a better coverage of the bed by the heat carrier ~:hich, in turn, helps increase the efficiency of heating the oil-bearing bed 7 and recovery factor thereo~.
At the same time, temperature conditions permissible from the standpoint of labor protection and safety regulations are maintained in the recovery gallery 9 ~Jhere most of the per-sonnel members are stationed.
The heating front having a ~reset temperature is grad-ually moving towards the recovery gallery 9 (in the direction of oil eYtraction via recovery wells) since the heat carrier is delivered via inlet wells 10 whose tops are near the faces of the recovery wells 11. Therefore, the extraction of oil and movement of the heating front are effected in the same direct-ion. The time of the heating front arrival to the recovery gal-lery 9 can be controlled by the delivery pressure and heat car-rier te~.perature, which, in turn, along with the better cover-age of the bed by the heat carrier, offers an im~ortant technol-ogical advantage such as the setting up of proper workin& con-ditions for the personnel in said recove~y gallery 9 owing to normalization of the tem~erature conditions of air in said gal-lery.
The inlet wells 10 and recovery wells 11 in the oil-bearin~ bed portion between the inlet gallery 8 and recovery ~i'73 gallery 9 are d~illed towards each other such that the~ should envelop the bed ~n a uniform network of ~ells.
The inlet ~ells 10 are drilled from the inlet ~allery 8 uniformly over the area under develo~ment. In ~articular, the inlet wells 10 may be drilled parallel to each other, as sho-:n in ~
The recovery wells 11 are drilled fro~ the reccvery gallery 9 (~igs. 2, 3) also uniformly over the area ~nder de-velo?ment such that the tops of the inlet ~ells be located near the faces o the recovery wells. In the case of a rectili-near recovery gallery 9, the recovery ~ells 11 are drllled pa-rallel to each other.
The heat carrier (for example, steam) is delivered to the tops of the inlet wells 10 from a boiler unit lc located on the ~round surface, via ground pipeline 13 throu~h a steam-supply well 14 and underground pipelines (not shown~ located in the drifts 4.
The heat carrier is injected into the oil-bearin~ bed 7 via system of inlet wells 10. Inasmuch as the to~s of the in-let wells 10 are located near the faces of the recovery wells 11, oil ~irst assumes desired fluidity in the portions of the oilbearing bed 7 adjoining the zone of the tops o~ the inlet wells 10.
Oil is fed via the shaft of the recovery well 11 to the recover~ gallery 9 and then to ditches or pipelines provided in the drifts 4.
Together with water supplied to the ditches or ?ipelin-es 9 oil is conveyed by gravity owing to the inclination of i'73~4 ~ 14 _ the workings to the horizon on the order of 1-3 toY~ards oil trapping units (not shown in the drawings) ~here it is sepa-rated from the bulk of water. Pumps can be used for conveying oil with associated ~ater to said units via pipelines. From the oil trappin~ units oil is ~umped over to central under-ground oil collectors (not sho~n in the dr2~!ings) from -nhich it is fed, followin~ ~rimary preparation and ?reheat, via Li-pelines and through special wells 15 or through the shaft in-to oil storage tanks 16 located on the ~round sur~ace.
The method will remain essentiall~ the same if the drifts 4 (~i~. 4) are provided below the oil-bearin~ bed 7.
r~oreover, such an arran~ement of the drifts offers better con-ditions for the delivery of oil thereinto from the recovery galleries 9.
In this case, the conveyance of oil can be effected by gravity from the top of the recovery wells 11 to the oil tran-ping units.
The inlet and recover~ ~alleries (8 and 9, res?ective-ly) may have the form of two twin workings (as shown in ~ig.2), as well as of a single workin~.
In any case, the extent of some or other ~alleries de-~ends, among other thi~s, upon the possibility of their re-liable airing in the course of driving and operation.
The oil well ventilation system should meet the re-ouirements of labor protection and safety regulations for the service personnel.
In another embodiment of the disclosed method, when the top portion of the oil-bearing bed 7 is made up of poorly 7~74 cemented, loose or markedly fissured rock, with a hi~h-~ressu-re water-bearin~ bed located below the oil-bearing bed, the in-let and recover~ galleries are located in the bottom ?ortion of the oil-bearin~ bed.
In this embodiment, follo~ing the settin~ u? o~ the ~lura-lity of underground workings (shafts, ~ine yard, s~aft .~.~orkin~s, drifts in the overlyin~ horizon, inclined workings), the method of the invention is accomplished by executin~ the following steps.
1~ Rectilinear recovery galleries 9 are ~rovided in the bottom portion of the oil-bearing bed 7 at a distance of 500--700 m from each other (~igs. 2, 3~;
~THOD OF ~INING AN OI~ DEPOSIT
The present invention relates to development of oil fields and, more particularl~, it relates to a method of ther-mal-mining production of oil and can be used in the ?etroleum industry.
This invention can be used most efficiently in the de-velopment of oil fields characterized by ~i~hly viscous oils and fluid asphalts.
The inven~ion can also be used for developing oil de-~osits with depleted reservoir energy.
At present, such deposits cannot be efficiently developed b~7 the conventional method wherein oil production is accom~lish ed with the aid of wells drilled from the ground surface. The resulting recovery is rather low.
Rnown in the art for developing oil fields with highly viscous oils and ~luid asphalts is a mining method of oil ~ro-duction without lifting oil-bearing rock to the earth's sur-face (cf., A.Ya. Krems et al., Shahtnaiya razrabotka neftianyh mestorozhdenii - ~he Mining of Oil Deposits, Gostoptehizdat Publishers, ~oscow, 1955).
Said prior art method comprises dr~ving, above the roof of the oil-bearing bed, a system of underground workings in-cluding fringe drifts with drill chambers. ~rom the drill cham-bers, inclined and straight wells are drilled whose denth de-pends on the thickness of the oil-bearing bed and the distance from its roof to the drill chambers. After drilling the wells, oil is reco~ered therefrom by the flowing method and then by air-lift.
','~
~ .
73'~1 -- 2 _ Wrhen employing the flowing method, oil is lifted from the oil-bearing bed throu~h the wells to the drill chambers by res~rvoir pressure; in the case of air-lift, compressed air is injected via pipes placed in the well. From the drill cham-bers, oil is delivered via underground workin~s to central un-derground oil collectors from ~hich it is pumped~ follo~?ing primary preparation and ~reheat, into tanks located on the ground surface.
This method helps increase the recovery by a factor of three and above as com~ared with the develo~ment by means of wells drilled from the earth's surface. However, the absol-ute value of recover~ amounts to only about 6~.
J.ow recovery caused a need to employ mining methods of oil production, which provide for ?hysically affectin~ an oil-bearing bed and the oil contained in the latter.
There is known in the art a method of thermal-minin~ ~ro-duction of oil involving the ex~osure of the bed to the effect of steam and heat (cf., V.N. Ihlishakov et al., O~yt primeneniya teplovyh metodov pri shahtnoi razrabotke mestorozhdenii vyso-koviazkih neftei - On the Use of Thermal Methods upon ~ining ~ighly Viscous Oil Deposits, in ~Teftianoye hozyiaistvo -Journal of Petroleum Industry, No~ 10, 197~, pp. 31-35).
Said prior art method ?rovides for driving above the oil-bearing bed a plurality of underground workings including shafts~ shaft workings, drifts and drill chambersO
From the drill chambers located in the drifts, straight and inclined inlet and recovery wells are drilled. A heat car-rier (steam) is supplied to the oil-bearing bed via inlet ~ i'7,3'79~
wells, which drives oil from the inlet wells to the recovery wells. ~rom the face of the recovery wells, oil is air-lifted to the drill chambers.
Said ~rior art method suffers from the sandin~ up of the recovery wells o?erating by the air-lift method and of the in-let wells. The recovery and inlet wells are clog~ed with sand from the bed.
In addition, the air-lift techni~ue of oil production calls for equi~ping the wells with special ripes or devices for closing and opening the supply of air, when reauired, whi-le considerable amounts of air are required for the delivery of liquid from the wells.
Said prior art method suffers from a low efficiency of the process of thermal~mining production of oil due to consid-erable heat losses through well walls into "barren", oil-free rock, as well as to large amount of drilling to be done in such rock.
According to still another prior art method of oil min-ing (cf., U.S. Patent No. 1,634,235), wells are drilled from underground ~workings located below the oil-bearing bed, and oil is extracted from shallow wells drilled from the bottom upwards. The underground workings are in this case arranged radially from the central shaft over the mining field area.
~ his ?rior art method ~rovides for extraction of oil from the bed by gravity while the face zone of the bed is heated by wa~ of supplying steam to the well face via pipes located in the wells.
Said method suffers from non-uniform arrangement of un-derground workings and wells over the mine field area. Mine 73~}4 field portions adjoining the shaft are developed with the aid of a dense network of wells. Bed portions remote from the shaft are developed with the aid of a s~arse network of wells.
Such an arrangement of wells resul~s in non-uniform mining of oil reserves.
~ here is further known a mining method of oil production (cf., U.~. Patent No. 1,520,737), according to which a vertic-al skaft is driven through the oil-bearing bed below which a drill chamber is arranged from which inclined and ascending wells are drilled in a radial direction.
A heat carrier ~steam) is su~plied to the oil-bearing bed through said wells via pipes having a diameter smaller than that of the well. Ileated oil ~lo~lJs down into the drill cham-ber after which it is ~umped up to the ground surface.
Although said prior art method makes for a si~nler pro-cess of oil recovery and an increased recovery, the bed por-tion under development is limited by the nossibilities of drilli~ the inclined wells or, to be more Drecise, by their length. Therefore, a limited bed ~ortion is to be provided with an individual shaft built from the earth's surface. This affects considerably the economic ~erformance of the latter ~rior art method.
Yet another mining method of developing an oil de~osit, known in the art, involves the heating of oil-bearing bed by ~eriodic injection of steam from underground workings located above a recovery gallery, via system of inlet wells.
~ ithout discontinuing the injection of steam, fluid such as oil and water is periodically extracted via recovery wells drilled from the recovery gallery located in the bottom ~or-l~tj~73'7 tion of the oil-bearing bed. This is followed by periodic injection of hot and then cold water, v~hile continuing the ex-traction of fluid via recovery wells.
This latter prior art method, regarded by the inventors as prototype of the method according to the present invention, is accom~lished in the form of either a two-horizon system or a two-stage system.
Both systems suffer from a non-uniform coverage of the oil-bearing bed by the displacement arocess and, as a result, from low recovery.
In the case of the two-horizon s~stem, large amounts of heat are lost to overlying rock through the walls of inlet wells, which affects the bed-heating efficiency.
In the case of the two-stage system, the bed-heating ef-ficiency is reduced considerably because of non-uniformity of thermal effect upon the oil-bearing bed, as a result of which the peripheral zones of the area under development are heated slowly and oil fails to assume desired fluidity, this leading to lower recovery.
It is the primary object of the present invention to de-velop a method of mining an oil deposit that would help in-crease the current oil production and the rate of oil extract-ion from the de~osit.
It is another object of this invention to develop a met-hod of mining an oil deposit that would help increase the ef-ficiency of thermal effect upon the bed.
It is still another object of the present invention to deveop a method of ~ining an oil deposit that would help re-73 y~
duce the amount of drilling to be done in "barren", oilfreerock.
Said and other objects of the present invention are ac-complished in the herein disclosed method of mining an oil deposit, which comprises:
- arran~ing a plurality of underground workings and re-covery galleries;
- drilling recovery wells in rows from said recovery ~Galleries;
- arranging inlet galleries, each of them in the bed bet-ween two recovery galleries near the faces of said recovery wells;
- drilling inlet wells from said inlet galleries towards said recovery wells such that said inlet and recovery wells should alternate in the oil-bearing bed portions between said inlet and recovery galleries to envelo~ the bed in a uniform networ~ of wells;
- force-feeding a heat carrier to the oil-bearing bed through said inlet ~ells for heating the bed to a temperature at which oil assumes desired fluidity in the latter and for dis~lacing oil to said recovery wells;
- extracting oil from the recovery wells to the recovery galleries; and - delivering oil from the recovery galleries via under-ground wcrkings to the ground surface.
The im~rovement of the method according to the present invention consists in that the inlet galle~ is arranged near the faces of the recoveFy wells, while ~he inlet and recovery y~
wells in the oil-bearing bed portion between the inlet and re-covery galleries are drilled towards each other such that they should envelop the bed in a uniform network of wells.
An increase of current oil ~roduction and of the rate of oil extraction from the oil-bearing bed is attained as a re-sult of heating the oil-bearin~ bed and oil contained in the latter and, consequently, as a result of reducing the oil vis-cosity, expanding oil and increasing reservoir ?ressure. Thanks to a better coverage of the bed by the ~rocess of oil displace-ment by the heat carrier and a more uniform heating of the bed, an increase in recovery is attained.
An increased efficiency of the bed heating process is attained as a result of reducing heat losses through the walls of inlet wells which are drilled in the oil-bearing bed, as well as owing to additional heating of the bed upon the in-flux of heated oil via shaft of the recovery well through less heated ~ortions of the bed.
The efficiency of the oil production process is attained owiDg to an increased recovery and higher rates of develo?-ing oil de~osits, as ~ell as owing to a manifold, sometimes complete, reduction of the amount of well drilling in "barren", oil-free rock.
The herein disclosed method provides for the maximum pos-sible degree of bed drainage by means of horizontal, flat-dipping and flat-raise wells which extend over the oil-bear-ing bed through dozens and hundreds of meters to interconnect its inhomogeneous zones, various channels, cracks and caverns and to increase the degree of bed completion.
J ~ti~73-~
The method of the invention further provides for ensur-in~, along ~ith the oil displacement mode, conditions requir-ed for a display of ~ravi-ty flow of oil, as well as the maxim-um possible simplification of the conditions of w211 o~eration It is exredient that in oil-bearing beds whose to~ ~or-tion is made u~ of poorly cemented loose rock or ~arkedly fis-sured rock, with hi~h-pressure water-bearing beds located be-low such oil-bearing beds, the inlet and recovery galleries should be located in the bottom portion of the oil-bearin~ bed ,'ith the inlet and recovery galleries located in the bot-tom Dortion of the bed, the inlet and recovery wells are fully located in ~he oil-bearing bed. Naturally, this hel~s fully eli-minate heat losses to "barren" rock through well walls due to heat conductivity. All of the heat is consumed for heating the oil-bearing bed.
It is further exnedient that in oil-bearing beds made u~
of ~oorly cemented and loose rock, with beds of stable and hard rock located therebelow, the inlet and recovery galleries should be located below the oil-bearin~ bed.
The arrangement of the recovery galleries below the oil--bearing bed makes for improved operating conditions of raise wells thanks to a reduced possibility of sand ~lugging. Under-ground air in the inlet and recovery galleries is im~roved owing to the location of said galleries in oilfree roc~.
Since the tops of the inlet and recovery wells are in a water-bearing bed, favorable conditions exist for their seal-ing. Shaft portions of wells drilled in water-bearing bed pre-sent, as a rule, an insignifacant fraction of the well lergth.
l~ti';''3'~'4 _ 9 ~
In this case, heat losses to "barren" rock are negligible owing, first, to a reliable insulation of the wells in the to~
portion and, second, to the tendency of heat to move upwards, i.e., to the zone of oil extraction from the derosit.
The present invention will be better understood u~on con-sidering the following detailed description of an exem?lary embodiment thereof, with due reference to the accomDanying drawings in which:
Figure 1 shows the variation of the mean tem?erature of the oil-bearing bed over the length of a horizontal inlet well;
Figure 2 is a plan view of a portion of oil-bearing bed under develo?ment with inlet and recovery wells and under-ground workings (underground workings and wells are conven-tionally superposed in a single horizontal plane);
Figure 3 is a section taken along the line III-III of Fig. 2 for the case when the inlet and recovery galleries are located in the bottom portion of the oil-bearing bed; ard Fi~ure 4 is a section taken along the line III-III of Fig. 2 for the case ~vhen the inlet and recovery galleries are located below the oil-bearing bed.
~ he herein disclosed method is realized in the follow-ing manner.
A plurality of underground workings is set up, including two shafts, namely, a winding shaft 1 (Figs. 2, 3) and a ven-tilating shaft 2, a mine yard 3 (Fig. 3), shaft workings which house a locomotive barn, a pumping station, storages etc. (not shown in the drawings), drifts 4, inclined workings 1 g ~;7374 5 and 6 (Figs. 2 and 3). The drifts 4 are driven sbove the roof of an oil-bearing bed 7 (~i~. 3) and inclined to the horizon at an angle of from 1 to 3.
The inclined Yorkings 5 and 6 are driven from the drifts 4 (Figs. 2 and 3) to the bottom portion of the bed or below the latter, where at least one inlet gallery 8 and recovery gallery 9 are set up.
The inlet galleries 8 are located near the faces of re-cover~7 wells (11). Both the inlet and ~ecoveI~ galleries (8 and 9, res~ectively) ma~ be rectilinear (as shown in ~ig. 2) or curvilinear, depending on the shape of the area under de-velopment.
Upon delivery of steam via horizontal or flat-raise inlet wells 10, pressure losses over the well length cause a nressu-re drop between the well top and face. At the same time, there is observed a tem~erature drop over the length of the inlet wells 10, caused by the transfer of heat to the oil-bearing bed 7 saturated Yiith liquids.
Since low delivery r!ressures are emplo~ed in oil ~ells, low-temperature steam arrives to the tops of the inlet wells 10, while it is practically a condensate (hot water) that ar-rives to the well faces. Curve A in ~i~. 1 indicates the mean temperature of the bed over the length of a horizontal well in one of the actual portions of the oil well.
~ n the bed zone adjoining the top portion of the inlet well 10 (~igs. 2 and 3), heating is carried out owing to heat conductivity inasmuch as this part of the well is cased witk a string. In the zone of the oil-bearing bed 7 (~ig~ 3) adjoin-3~
ing the face portion of the inlet well 10, the bed is heatedowing to convection heat transfer. In the face portion of said well, the pressure and tem~erature are rather low and have no considerable effect u?on the heating of the oil-bearin~ bed 7.
When delivering steam at low pressures, as is often the case, the heating of the oil-bearing bed 7 is ~ainl~ accomplish-ed owing to ~eat conductivity from the shafts of the horizontal inlet wells 10.
As seen from the chart (curve A) showing the well len~th dependence of the mean temperature (~ig. 1~, the hi~hest tem-perature is observed in the top portion of the well. ~his en-tails an increase ol the temDerature of the walls of the gal-lery 8 (~igs. 2 and 3) from which the wells are ~rilled, as well as an increased release of heat to underground air. If both inlet and recovery wells are located in one and the same gallery, this leads to aegravation of the workin~ conditions for the personnel engaged in the recovery of oil from the re-covery wells.
An increase of the amount of air used for airing caus-es large heat losses from the bed which, in turn, affects ad-versely the heatin~ efficiency and the heat balance of the rrocess of thermally influencing the oilbearln~ bed 7 (~ig. 3).
In order to eliminate the afore-described disadvantages, the inlet and recovery galleries (8 and 9, res~ectively) are located in the bottom portion of the oil-bearin~ bed 7 or be-low the latter, the inlet galleries 8 bein~ located near the faces of the bottom row of the recovery wells 11.
Oil assuming desired fluidity in the portions adjoining .the tops of the inlet wells 10 arrives to the faces of the ``` l.~ti'~3'~
recovery wells 11 and then, via shafts of the recovery wells 11, to the recovery gallery 9. The heat received by oil in said zone is partly transferred to the bed upon oil ~,ovement towards the recovery gallery 9. This r.a~es for the heating of the oilbearin~, bed 7 over the entire volume thereof thanks to a better coverage of the bed by the heat carrier ~:hich, in turn, helps increase the efficiency of heating the oil-bearing bed 7 and recovery factor thereo~.
At the same time, temperature conditions permissible from the standpoint of labor protection and safety regulations are maintained in the recovery gallery 9 ~Jhere most of the per-sonnel members are stationed.
The heating front having a ~reset temperature is grad-ually moving towards the recovery gallery 9 (in the direction of oil eYtraction via recovery wells) since the heat carrier is delivered via inlet wells 10 whose tops are near the faces of the recovery wells 11. Therefore, the extraction of oil and movement of the heating front are effected in the same direct-ion. The time of the heating front arrival to the recovery gal-lery 9 can be controlled by the delivery pressure and heat car-rier te~.perature, which, in turn, along with the better cover-age of the bed by the heat carrier, offers an im~ortant technol-ogical advantage such as the setting up of proper workin& con-ditions for the personnel in said recove~y gallery 9 owing to normalization of the tem~erature conditions of air in said gal-lery.
The inlet wells 10 and recovery wells 11 in the oil-bearin~ bed portion between the inlet gallery 8 and recovery ~i'73 gallery 9 are d~illed towards each other such that the~ should envelop the bed ~n a uniform network of ~ells.
The inlet ~ells 10 are drilled from the inlet ~allery 8 uniformly over the area under develo~ment. In ~articular, the inlet wells 10 may be drilled parallel to each other, as sho-:n in ~
The recovery wells 11 are drilled fro~ the reccvery gallery 9 (~igs. 2, 3) also uniformly over the area ~nder de-velo?ment such that the tops of the inlet ~ells be located near the faces o the recovery wells. In the case of a rectili-near recovery gallery 9, the recovery ~ells 11 are drllled pa-rallel to each other.
The heat carrier (for example, steam) is delivered to the tops of the inlet wells 10 from a boiler unit lc located on the ~round surface, via ground pipeline 13 throu~h a steam-supply well 14 and underground pipelines (not shown~ located in the drifts 4.
The heat carrier is injected into the oil-bearin~ bed 7 via system of inlet wells 10. Inasmuch as the to~s of the in-let wells 10 are located near the faces of the recovery wells 11, oil ~irst assumes desired fluidity in the portions of the oilbearing bed 7 adjoining the zone of the tops o~ the inlet wells 10.
Oil is fed via the shaft of the recovery well 11 to the recover~ gallery 9 and then to ditches or pipelines provided in the drifts 4.
Together with water supplied to the ditches or ?ipelin-es 9 oil is conveyed by gravity owing to the inclination of i'73~4 ~ 14 _ the workings to the horizon on the order of 1-3 toY~ards oil trapping units (not shown in the drawings) ~here it is sepa-rated from the bulk of water. Pumps can be used for conveying oil with associated ~ater to said units via pipelines. From the oil trappin~ units oil is ~umped over to central under-ground oil collectors (not sho~n in the dr2~!ings) from -nhich it is fed, followin~ ~rimary preparation and ?reheat, via Li-pelines and through special wells 15 or through the shaft in-to oil storage tanks 16 located on the ~round sur~ace.
The method will remain essentiall~ the same if the drifts 4 (~i~. 4) are provided below the oil-bearin~ bed 7.
r~oreover, such an arran~ement of the drifts offers better con-ditions for the delivery of oil thereinto from the recovery galleries 9.
In this case, the conveyance of oil can be effected by gravity from the top of the recovery wells 11 to the oil tran-ping units.
The inlet and recover~ ~alleries (8 and 9, res?ective-ly) may have the form of two twin workings (as shown in ~ig.2), as well as of a single workin~.
In any case, the extent of some or other ~alleries de-~ends, among other thi~s, upon the possibility of their re-liable airing in the course of driving and operation.
The oil well ventilation system should meet the re-ouirements of labor protection and safety regulations for the service personnel.
In another embodiment of the disclosed method, when the top portion of the oil-bearing bed 7 is made up of poorly 7~74 cemented, loose or markedly fissured rock, with a hi~h-~ressu-re water-bearin~ bed located below the oil-bearing bed, the in-let and recover~ galleries are located in the bottom ?ortion of the oil-bearin~ bed.
In this embodiment, follo~ing the settin~ u? o~ the ~lura-lity of underground workings (shafts, ~ine yard, s~aft .~.~orkin~s, drifts in the overlyin~ horizon, inclined workings), the method of the invention is accomplished by executin~ the following steps.
1~ Rectilinear recovery galleries 9 are ~rovided in the bottom portion of the oil-bearing bed 7 at a distance of 500--700 m from each other (~igs. 2, 3~;
2~ in the desi~n zone of the faces of the bottom row o~
the inlet wells 11 there are arranged rectilinear inlet Fal-leries 8 located between the recovery galleries 9 in the bot-tom portion o~ the bed (in the top portion of the zone of transition from oil to bottom water);
the inlet wells 11 there are arranged rectilinear inlet Fal-leries 8 located between the recovery galleries 9 in the bot-tom portion o~ the bed (in the top portion of the zone of transition from oil to bottom water);
3) recover~ and inlet wells (10 and 11, res?ectivel~) are drilled at a distance of 1O-L~O m between each other in the ~ortion of the oil-bearin~ between the inlet and recovery galleries (8 and 9, res?ectively). The wells are arran~ed in several rows (layers) over the bed thickness. ~n each row (la~7er), the inlet and recovery wells (10 and 11, respective-ly) are arranged alternately with each other or, de~ending up-on geological conditions, several (2 to 5) recovery wells 11 are located between two inlet v~ells 10.
4) the heat carrier (such as steam) is injected into the oil-bearing bed 7 v a inlet wells 10 at a pressure of from 3 to 10 kgf/cm S with time interYals of from 15 to 30 days and pauses of the same duration.
737~
Then, all of the inlet ~Jells 10 of the element (area3 under development are divided into grou?s, with the deliver~
of steam into each one of them bein~ effected alternately, with the afore-mentioned time intervals of steam injection and shutdo~n of inlet wells 10;
737~
Then, all of the inlet ~Jells 10 of the element (area3 under development are divided into grou?s, with the deliver~
of steam into each one of them bein~ effected alternately, with the afore-mentioned time intervals of steam injection and shutdo~n of inlet wells 10;
5) intermittent extraction of fluid (oil and water) is effected from the recovery wells 11;
6) the cgcles of heat carrier injection into the bed and oil extraction are repeated until full economicall~ rractical recovery of oil from the area under development.
In still another embodiment of the method of the inven-tion in the case of oil-bearing beds 7 made up of poorly cem-ented and loose rock, tl~ith beds of stable and hard rock locat-ed therebelow, inlet and recovery wells (8 and 9, res~ective-ly) (~ig. 4) are located below the oil-bearing bed.
In this latter case, the method of the invention can be accomplished mainly through the execution of the aforedescribed steps, ~ith due regard for the above-mentioned arran~ement of the inlet and recovery galleries (8 and 9, resnectively).
The operating conditions of the recover~ wells 11 accord-ing to said latter embodiment are improved over those described above Ovl!in~ to a reduced possibility cf sand ~lu~ging. Under-ground air in the workings is likewise improved owin~ to the location of the latter in oil-free rock.
The use of the herein disclosed method of mining an oil deposit results in an increased current ~roduction of oil and rate of oil extraction from the oil-bearing bed 7. Conditions are provided for a more uniform and in~ensive heating of the 3~4 oil-bearin~t bed, as well as for a fuller coverage of the bed by the ~rocess of oil dis~lacement by the heat carrier, which makes for an increased recovery and, as a result, for hi~her efficienc~ of the ~roduction of hi~-~hl~ viscous oil.
The r~resent invention can be used no less advanta~eously in the -?roduction of fluid as~halts.
In still another embodiment of the method of the inven-tion in the case of oil-bearing beds 7 made up of poorly cem-ented and loose rock, tl~ith beds of stable and hard rock locat-ed therebelow, inlet and recovery wells (8 and 9, res~ective-ly) (~ig. 4) are located below the oil-bearing bed.
In this latter case, the method of the invention can be accomplished mainly through the execution of the aforedescribed steps, ~ith due regard for the above-mentioned arran~ement of the inlet and recovery galleries (8 and 9, resnectively).
The operating conditions of the recover~ wells 11 accord-ing to said latter embodiment are improved over those described above Ovl!in~ to a reduced possibility cf sand ~lu~ging. Under-ground air in the workings is likewise improved owin~ to the location of the latter in oil-free rock.
The use of the herein disclosed method of mining an oil deposit results in an increased current ~roduction of oil and rate of oil extraction from the oil-bearing bed 7. Conditions are provided for a more uniform and in~ensive heating of the 3~4 oil-bearin~t bed, as well as for a fuller coverage of the bed by the ~rocess of oil dis~lacement by the heat carrier, which makes for an increased recovery and, as a result, for hi~her efficienc~ of the ~roduction of hi~-~hl~ viscous oil.
The r~resent invention can be used no less advanta~eously in the -?roduction of fluid as~halts.
Claims (3)
1. A method of mining an oil deposit, wherein: a plur-ality of underground workings and recovery galleries are arr-anged in the oil deposit;
recovery wells are drilled in rows from said recovery galleries;
inlet galleries are arranged, each located in a bed between two of said recovery galleries near the faces of said recovery wells; inlet wells are drilled from said inlet galleries to-wards said recovery wells such that said inlet and recovery wells alternate in oil-bearing bed portions between said inlet and recovery galleries to envelop the oil-bearing bed in a uniform network of wells;
a heat carrier is delivered to the oil-bearing bed through said inlet wells for heating the bed to a temperature at which oil assumes desired fluidity in said bed and for displacing oil to said recovery wells;
oil is extracted from said recovery wells to said recovery galleries;
oil is conveyed from said recovery galleries via said workings to the ground surface.
recovery wells are drilled in rows from said recovery galleries;
inlet galleries are arranged, each located in a bed between two of said recovery galleries near the faces of said recovery wells; inlet wells are drilled from said inlet galleries to-wards said recovery wells such that said inlet and recovery wells alternate in oil-bearing bed portions between said inlet and recovery galleries to envelop the oil-bearing bed in a uniform network of wells;
a heat carrier is delivered to the oil-bearing bed through said inlet wells for heating the bed to a temperature at which oil assumes desired fluidity in said bed and for displacing oil to said recovery wells;
oil is extracted from said recovery wells to said recovery galleries;
oil is conveyed from said recovery galleries via said workings to the ground surface.
2. A method as set forth in claim 1, wherein said inlet and recovery galleries are located in the bottom portion of the oil-bearing bed.
3. A method as set forth in claim 1, wherein said in-let and recovery galleries are located below the oil-bearing bed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000368205A CA1167374A (en) | 1981-01-09 | 1981-01-09 | Method of mining an oil deposit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000368205A CA1167374A (en) | 1981-01-09 | 1981-01-09 | Method of mining an oil deposit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1167374A true CA1167374A (en) | 1984-05-15 |
Family
ID=4118878
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000368205A Expired CA1167374A (en) | 1981-01-09 | 1981-01-09 | Method of mining an oil deposit |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1167374A (en) |
-
1981
- 1981-01-09 CA CA000368205A patent/CA1167374A/en not_active Expired
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