CN105178931A - Method for increasing initial production speed of SAGD (Steam Assisted Gravity Drainage) - Google Patents
Method for increasing initial production speed of SAGD (Steam Assisted Gravity Drainage) Download PDFInfo
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Abstract
The invention provides a method for increasing initial production speed of SAGD (Steam Assisted Gravity Drainage). The method comprises the steps as follows: minimum principal stress of reservoirs of an oil deposit is ensured to be in the horizontal direction; 2), a steam injection well and a production well are arranged in the vertical direction of the oil deposit respectively; 3), a liquid-phase mixed solvent is injected into the production well and the steam injection well by stages, so that inter-well pressure is formed and the wells are communicated; besides, a vertical dilatation zone is formed above the horizontal wells; 4), after the liquid-phase mixed solvent is enabled to enter the dilatation zone and is immersed, a vertical low-viscosity region is formed above the steam injection well; 5), steam is injected into the two horizontal wells, or steam is injected into the production well separately, and circulating preheating is carried out; and 6), a semi-SAGD stage is shifted to, and when injection withdrawal balance between the two wells is realized and the production well and the steam injection well are in the same pressure system, a normal SAGD stage is shifted to. According to the method, the initial low-yielding time of traditional SAGD is reduced; the initial production speed and the initial oil-producing rate of the SAGD are increased; the arrival of the peak oil production is accelerated; and the economic benefit of the project is increased.
Description
Technical field
The present invention relates to a kind of method improving product speed on the SAGD initial stage, belong to field of petroleum exploitation.
Background technology
Crude viscosity under reservoir temperature is reached to the heavy crude reservoir of 10000mPas, SAGD is a kind of development technique of high-efficiency and economic, it by making a call to the horizontal well pair of a pair vertical distance 5 meters bottom oil reservoir, in upper water horizontal well, inject steam continuously, in bottom water horizontal well, pump extraction goes out viscous crude and the condensed water of heating.
SAGD produce oil rule (as shown in Figure 1) is generally divided into: the three phases such as the plateau (vapor chamber is extending transversely) after rising (corresponding vapor chamber uphill process), peak value, oil production decay (vapor chamber decline).The rate of climb slow (as shown in Figure 6) of usual initial stage vapor chamber, for one be deployed in SAGD well in 30 meters of thick oil pays for, production cycle average out to about 10 years, and vapor chamber may need 2-3 to top, this stage oil production is low, steam consumption is large, and cause whole SAGD cumulative gas-oil ratio low, economy is not good.
Therefore, improve product speed on the SAGD initial stage and become one of this area problem demanding prompt solution.
Summary of the invention
For solving the problems of the technologies described above, the object of the present invention is to provide a kind of method improving product speed on the SAGD initial stage, the method is by geostatic stress regulable control, solvent soaking and oil recovery by heating, traditional SAGD initial stage low yield time can be reduced, improve product speed and initial stage produce oil speed on the SAGD initial stage, accelerate the arrival of peak value output, improve Project Economy Benefit.
For achieving the above object, the invention provides a kind of method improving product speed on the SAGD initial stage, the method comprises the following steps:
Step one, determine that the reservoir minimum principal stress of oil reservoir (puts before this and could produce vertical dilatation band) in the horizontal direction;
Step 2, dispose a pair horizontal well in the vertical direction of described oil reservoir, wherein, the horizontal well on vertical direction top is steam injection well, and the horizontal well of vertical direction bottom is producing well;
Step 3, in described producing well and steam injection well, inject liquid phase mixed solvent stage by stage, described producing well and described gas injection well is made to form inter-well pressure UNICOM, and above described horizontal well, form vertical dilatation band (technical scheme provided by the invention can, in the process of reservoir being carried out to extending capacity reformation, be avoided destroying cap rock or form not controlled large fracture equivalent risk in reservoir by injecting liquid phase mixed solvent stage by stage);
Step 4, in the dilatation band described liquid phase mixed solvent being entered formed in step 3, soak, in the vertical low-viscosity region of the aboveground square one-tenth of described steam injection (by soaking, liquid phase mixed solvent can dissolve to adjacent viscous crude is middle mutually, diffusion, the low-viscosity region that formation one is vertical above steam injection well), viscosity in this low-viscosity region is less than the viscosity of reservoir viscous crude, and (this Di Nian district is relative reservoir viscous crude, its size depends on the dilatation district of the aboveground square one-tenth of steam injection, the viscosity scope in this low-viscosity region is subject to the kind of solvent, the impact of the factors such as the content of solvent and the viscosity of reservoir viscous crude, experimentally measurement result, for xylene solvent, the quality percentage of solvent is 10%, and the viscosity of reservoir viscous crude 50 DEG C time is 100000mPas, and the viscosity after mixing 70 DEG C time is 1000mPas),
Step 5, inject steam to described producing well and steam injection well, or inject steam to described producing well separately, carry out cyclic preheat, when described producing well and described steam injection well form Jing Jian heating power UNICOM, stop injecting steam;
Step 6, proceeded to for half SAGD stage, when described producing well and described steam injection well form balanced flood, and described producing well and described steam injection well when being in same pressure system (producing well and steam injection well inter-well pressure UNICOM even), stop half SAGD operation, proceed to the normal SAGD stage (after above-mentioned steps three end, pressure UNICOM is defined between well, but because between well, Viscosity of Heavy Crude Oil is high, stress reaction is delayed larger, in half SAGD operation, not only noted but also adopted (when injecting steam to steam injection well by steam injection well, inject from long tube, short tube returns row) and producing well only adopt and do not note, the object of Jing Jian heating power UNICOM and fluid communication can be reached, now the crude oil that is heated of top can leak in producing well very smoothly under gravity, if and do not add this step, possible part Jing Jian heating power UNICOM or fluid communication are not set up completely, turning by force SAGD can cause pressure reduction between well large, part well section breaks through UNICOM, and other parts cannot UNICOM on horizontal segment.Thus half SAGD is one and falls low-risk transitional link).
Technical scheme provided by the invention creatively proposes: first determine reservoir minimum principal stress in the horizontal direction, then according to this prerequisite at the vertical dilatation band being full of solvent of the aboveground square one-tenth one of steam injection, and by soaking the vertical low-viscosity region of formation one, impel after turning SAGD, vapor chamber is grown fast in this low-viscosity region, and fast to top, thus improve the draining speed at SAGD initial stage.
In the above-mentioned methods, preferably, step at the beginning before, also be included on the well group in territory, same oil Tibetan area and carry out detecting earth stress, test the step (this step can obtain reservoir minimum principal stress, the secure reference data as subsequent operation) of minimum principal stress of the cap rock of same layer position, reservoir, substrate rock stratum respectively.
In the above-mentioned methods, preferably, in step 2, the distance bottom described producing well distance oil reservoir is less than 1m; More preferably, described producing well and described horizontal well distance are in the vertical direction 5m.
In the above-mentioned methods, preferably, in step 3, the composition of described liquid phase mixed solvent comprises dimethylbenzene and/or gas-oil (gas-oil is on-the-spot reservoir viscous crude through air-distillation, the mixture of boiling point in diesel oil section that extract), but be not limited thereto, those skilled in the art can consider according to the safety of execute-in-place, heat stability, cost, the combined factors such as ready availability, select suitable liquid phase mixed solvent, in the application dimethylbenzene and gas-oil used in combination time, the mixed proportion both can controlling according to the needs of actual cost; More preferably, the viscosity of described liquid phase mixed solvent is less than 1cP, and viscosity is low is conducive to the diffusion of pressure in down-hole, accelerates the enforcement of this measure.
In the above-mentioned methods, preferably, in step 3, comprise the following steps when injecting liquid phase mixed solvent stage by stage in described producing well and described steam injection well:
A, starting stage: inject liquid phase mixed solvent to improve down-hole pressure to described producing well and described steam injection well simultaneously, in the process improving down-hole pressure, the down-hole pressure reduction between described producing well and described steam injection well is kept to be less than 500kPa, and the injection rate of monitor well downforce and liquid phase mixed solvent;
B, pressure test stage: the down-hole pressure reducing wherein a bite well, maintain that the down-hole pressure of another mouthful of well is constant carries out pressure test, whether exist by the pressure field judging centered by producing well and steam injection well and influence each other, influence each other if existed, stop pressure test, proceed to the operation of step c; Otherwise continue the operation of above-mentioned steps a;
C, crack initiation UNICOM stage: continue the down-hole pressure improving steam injection well, when the down-hole pressure of steam injection well continues to rise, when starting to decline after reaching peak value, the injection flow maintaining liquid phase mixed solvent in steam injection well is constant, maintain near stable pressure to make down-hole pressure and fluctuate, now form the microfissure of some UNICOMs between producing well and gas injection well, what fill in these microfissures is the liquid phase mixed solvent injected, the dilatation band that above two horizontal wells, formation one is vertical; Wherein, described peak value is the initial cracking pressure in crack, and described stable pressure is the propagation pressure in crack; More preferably, improve in step a in the process of down-hole pressure, the hoisting velocity of controlled pressure (in the hoisting velocity of starting stage control well downforce within 0.4KPa/h, can be avoided injecting the too fast formation causing large fracture, even destroy cap rock) within 0.4KPa/h.
In the above-mentioned methods, preferably, after step c terminates, the method also comprises the step of carrying out the test of inter-well pressure UNICOM, the operating process of this step comprises the down-hole pressure improving producing well, the down-hole pressure maintaining steam injection well is constant, then inter-well pressure UNICOM situation is observed, when inter-well pressure presents the servo-actuated of a kind of large time delay on pressure-detecting device, the success of explanation extending capacity reformation, when inter-well pressure responds fast on pressure-detecting device, then illustrate and formed the large fracture run through between well, extending capacity reformation failure.
In the above-mentioned methods, preferably, in step c, when the down-hole pressure of steam injection well continues to rise, after reaching peak value, the method also comprises the step of pressure when taking the mode of closing well to test closing up of cracks, wherein, pressure during described closing up of cracks is reservoir minimum principal stress.
In the above-mentioned methods, preferably, in step 4, in the dilatation band described liquid phase mixed solvent being entered formed in step 3, soak, the low-viscosity region vertical at the aboveground square one-tenth of described steam injection comprises following operating procedure:
Improve the down-hole pressure of described steam injection well, when the reservoir minimum principal stress of described down-hole pressure higher than described oil reservoir, control the actual flow injection flow-liquid phase mixed solvent of this flow=liquid phase mixed solvent (return discharge capacity) entering the liquid phase mixed solvent of reservoir, guarantee that the down-hole pressure of described steam injection well is less than the cap rock main stress bar of described oil reservoir, the liquid phase mixed solvent major part now injecting reservoir enters in dilatation band; When the injection rate of liquid phase solvent in described steam injection well reaches preset value, (this preset value is relevant with the dilatation district size that expection is formed, depend primarily on the thickness of oil reservoir, degree of porosity etc., in the pressure limit of safe and reasonable, the dilatation district of the larger formation of amount of injecting is larger, 3% of the dilatation district volume that during field operation, this preset value can be formed according to expection calculates), stop injecting, closing well soaks; More preferably, the time that described closing well soaks is 1 day.
In the above-mentioned methods, preferably, in immersion process, the method also comprises monitor well downforce, fills into liquid phase mixed solvent to maintain down-hole pressure, to expand the step of described low-viscosity area thickness, the thickness in low-viscosity region is larger, then the volume in this low-viscosity region is also larger, the speed of SAGD initial stage vapor chamber expansion is faster, business efficiency is better, but increase the factor such as diffusion velocity, injection pressure size, injection quantity of solvent that thickness is limited by solvent, thus should increase its thickness as much as possible in safety, the acceptable situation of cost.
In the above-mentioned methods, preferably, described down-hole pressure is calculated by well head pressure+vertical section head of liquid and obtains; More preferably, described raising down-hole pressure is by improving clean injection rate, namely maintains the injection constant flow of described liquid phase mixed solvent, and that reduces described liquid phase solvent returns that discharge capacity carries out operating.
In the above-mentioned methods, preferably, in step 5, inject steam to described producing well and steam injection well, or when injecting steam to described producing well separately, control the pressure of described steam higher than reservoir hole pressure, and lower than reservoir minimum principal stress; More preferably, when carrying out cyclic preheat, described preheating time is 1 week.
In the above-mentioned methods, preferably, in step 6, the described half SAGD stage comprises carries out vapor recycle to described steam injection well injection steam, adopts the step of liquid from described producing well; The described normal SAGD stage comprises injects steam to described steam injection well, from the step that producing well recovers the oil.
In the above-mentioned methods, preferably, in step 2, described producing well and described steam injection well adopt barefoot completion and in horizontal well under enter cutting seam sieve tube completion; In cutting seam sieve tube, enter down each one of length oil pipe respectively, wherein, described short tube oil pipe is positioned at the horizontal segment starting point of horizontal well, and long tube is positioned at the horizontal segment terminal of horizontal well.
In the above-mentioned methods, preferably, after step 2 terminates, before step 3 starts, the method also comprises carries out pretreated step to the pit shaft of described producing well and described steam injection well, more preferably, described pretreatment comprises use clear water and carries out cleaning rear (can ensure that the liquid phase mixed solvent injected from well head enters reservoir by carrying out the borehole wall cleaning) to the borehole wall of described pit shaft, use on-the-spot high temperature mineralized water to carry out circulating in described producing well and described steam injection well (use high temperature mineralized water carry out circulating repeatedly heated well wall energy enough make the viscosity of near wellbore zone part viscous crude decline) or described liquid phase mixed solvent to be injected in described producing well and described steam injection well and the step of soaking (use liquid phase mixed solvent soaks, liquid phase mixed solvent can dissolve in viscous crude, diffusion, thus reduce the viscosity of viscous crude).
Beneficial effect of the present invention:
1) traditional scheme mainly concentrates on quick, the even UNICOM between dual horizontal well, and technical scheme provided by the invention creatively proposes: first determine reservoir minimum principal stress in the horizontal direction, then above horizontal well, a vertical dilatation band being full of solvent is formed according to this prerequisite, and by soaking the vertical low-viscosity region of formation one, impel after turning SAGD, vapor chamber is grown fast in this viscosity region, ground, and fast to top;
2) compared with traditional scheme, the fluid column effective height the highest (having arrived top) that technical scheme provided by the invention is formed due to the crude oil that is heated, thus gravity drainage speed is fast;
3) compared with traditional scheme, in the technical scheme that the invention provides, steam is larger with the contact area not employing heavy crude reservoir, and heat-transfer effect is better, and economic benefit significantly improves.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of SAGD produce oil rule;
Fig. 2 is the 3 D stereo schematic diagram after reservoir injection liquid phase mixed solvent carries out extending capacity reformation;
Fig. 3 is the effect schematic diagram that reservoir injects liquid phase mixed solvent and carries out after extending capacity reformation on the vertical cross-section crossing horizontal well;
Fig. 4 is that reservoir injects liquid phase mixed solvent and carries out after extending capacity reformation perpendicular to the effect schematic diagram on the vertical cross-section of horizontal well;
Fig. 5 is the development models schematic diagram using liquid phase mixed solvent to carry out vapor chamber after dilatation;
Fig. 6 is the development models schematic diagram in conventional vapor chamber.
Detailed description of the invention
In order to there be understanding clearly to technical characteristic of the present invention, object and beneficial effect, existing following detailed description is carried out to technical scheme of the present invention, but can not be interpreted as to of the present invention can the restriction of practical range.
Following examples are carried out following target reservoir, this target reservoir buried depth 440m, and average Crude viscosity during 50 DEG C, this oil reservoir is 106000mPas, oil density is 0.9677g/cm, degree of porosity is 30%, and permeability is 1.4 darcies, and on-the-spot test minimum principal stress is 6.3MPa.
Embodiment
Present embodiments provide a kind of method improving product speed on the SAGD initial stage, it comprises the following steps:
1) bore completion: bore well-completing process with traditional dual horizontal well SAGD and require identical, first at the location arrangements bottom water horizontal well being less than 1 meter bottom oil reservoir, be designated as producing well (P well); Then, under the guiding of magnetic steering, a parallel horizontal well is made a call at 5 meters of above it, is designated as steam injection well (I well); Horizontal segment length 400 meters, borehole diameter 8.5in; The projection in the horizontal plane of horizontal well group is selected at biggest principal stress direction as far as possible; Barefoot completion and in horizontal well under enter cutting seam sieve tube completion; Tubular column structure is identical with traditional dual horizontal well SAGD, each one of length oil pipe is entered down respectively in cutting seam sieve tube, wherein short tube is lowered near the horizontal segment starting point of horizontal well, and long tube is lowered into the afterbody of horizontal segment, and in well under enter corresponding temperature, pressure monitoring pipeline;
2) pit shaft pretreatment: use clear water repeatedly to clean borehole wall mud after boring completion, do acidification if desired, ensures that injecting fluid from well head can enter into reservoir; On-the-spot high temperature mineralized water (after boiler wastewater process) can be used in dual horizontal well inner loop, and method injects from long tube, returns out from short tube, or inverse operation, and after repeatedly heating the borehole wall, near wellbore zone part Viscosity of Heavy Crude Oil declines; Or, also after having cleaned mud, mixed solvent can be injected and soaks, rely on the dissolving of solvent in viscous crude, spread the viscosity reducing viscous crude;
3) detecting earth stress: select other representative well group of same block (namely to refer to represent the well group of the crustal stress states of this block from geomechanics angle, the well group using block edges, have the situations such as intrinsic fracture growth should be avoided), test the minimum principal stress with the cap rock of layer position, reservoir, substrate rock stratum, obtain the reference data of minimum principal stress;
4) extending capacity reformation: first (the liquid phase mixed solvent that the present embodiment uses is dimethylbenzene and gas-oil to IP well simultaneous implantation liquid phase mixed solvent, both mixed proportions can control according to the needs of running cost) to improve the down-hole pressure of IP well, (down-hole pressure is drawn by well head pressure+vertical section head of liquid reckoning, the mode of operation of pressure-raising is that to maintain the injection flow of liquid phase mixed solvent constant, that reduces liquid phase mixed solvent returns discharge capacity, namely clean injection rate is improved), in the process improving down-hole pressure, the down-hole pressure reduction between described producing well and described steam injection well is kept to be less than 500kPa, simultaneously, the hoisting velocity of controlled pressure is within 0.4KPa/h, the fluid liquid measure of continuous monitor well downforce and injection reservoir, the liquid measure that this process enters reservoir is very low,
Then reduce the down-hole pressure of I well or P well, maintain the down-hole pressure of another mouthful of well, test between two wells whether have certain stress reaction, when low pressure borehole pressure slowly slightly rises, show to there is stress reaction between two wells, stop test;
Then the crack initiation UNICOM stage is proceeded to: (mode of operation of pressure-raising is the same: maintain injection flow constant for the pressure first further in the slow I of raising well, reduce and return discharge capacity), continue to rise when monitoring down-hole pressure, when falling after rise after peaking, (this surge pressure is fracture initiation pressure, after reaching fracture initiation pressure, pressure when taking the mode of closing well to test closing up of cracks, be minimum principal stress), change the injection constant flow keeping liquid phase mixed solvent into, the situation of change of strict monitor well downforce, when maintaining fluctuation (this comparatively stable force value is propagation pressure) near a comparatively stable force value after down-hole pressure falls after rise,
Next, can reverse operating, namely improve the injection pressure in P well, the down-hole pressure maintaining I well is constant, the fluid communication between strengthening IP well;
Carry out the test of pressure UNICOM subsequently, namely reduce the down-hole pressure of a certain well, maintain the down-hole pressure of another well, observe pressure UNICOM situation, if extending capacity reformation success, pressure can present the servo-actuated of a kind of large time delay, if responded fast, the large fracture having been formed between well and run through is described, transforms unsuccessfully;
After extending capacity reformation success, a vertical dilatation band above horizontal well, can be formed, as shown in Figure 2,3, 4 (σ H – reservoir-level major principal stress in Fig. 2; The vertical main stress bar of σ v-reservoir; σ h-reservoir-level minimum principal stress);
5) soak: shut-down operation after P well maintenance down-hole pressure, inject liquid phase mixed solvent by the long tube of I well, short tube pressurized control liquid phase mixed solvent returns out, and improve constantly well head pressure, reservoir operating pressure also constantly rises; After down-hole pressure is higher than reservoir minimum principal stress, the actual flow (this flow=injection flow-return discharge capacity) entering the liquid phase mixed solvent of reservoir of strict control, guarantee that down-hole pressure rises no longer fast, even close to cap rock main stress bar (if there is this trend, suitably can improve discharge speed), the fluid major part now injecting reservoir enters dilatation district, this process lasts slowly carries out, till the injection rate reaching setting (injection rate of this setting can be formulated according to the imbibition ability of unit length net horizontal section during on-the-spot Jing Jian UNICOM); Then close note, valve door, in the change of well head monitoring pressure, if pressure drop slowly, can keep this state and closing well soaks more than one day, in immersion process, the aboveground side of steam injection can form a vertical low-viscosity region; If pressure declines fast, and when pressing close to reservoir hole, a certain amount of solvent can be supplemented again, maintain down-hole pressure, expand the thickness in low-viscosity region;
6) high steam circulation between IP well: when high pressure hydration is after more than a day, in P well, inject high temperature and high pressure steam carry out circulating (or IP well inject steam circulate) simultaneously, steam injects from long tube, returns out from short tube, and steam pressure should higher than reservoir hole pressure and lower than reservoir minimum principal stress; Cyclic preheat is after one week, thermal communication state between testing well, method of testing is: take P well (to enter temperature test pipeline under generally in P well, due to long-term steam injection in I well, generally no longer dispose temperature measuring equipment) stop vapor recycle, the change of monitoring downhole temperature; When downhole temperature first decline afterwards go up response fast time, can judge that the thermal communication situation in this well section is better; If UNICOM's degree of whole net horizontal section reaches design objective, HTHP steam injected cycle can be stopped;
7) in the half SAGD stage: then proceeded to for half SAGD stage, still maintain higher operating pressure, this stage I well continues steam injected cycle, and (short tube injects, and long tube returns out; Or contrary), P well only adopts liquid from short tube, and the middle steam injection amount maintaining I well is constant, and that constantly reduces I well returns discharge capacity, the Liquid output of monitoring P well and temperature, pressure change; When the Liquid output in P well increases fast, whole well to reaching balanced flood, and when P well and I well are in same pressure system completely, can stop half SAGD operation;
8) the normal SAGD stage:
1. high pressure SAGD: proceed to the SAGD initial stage, still maintain operation with high pressure, reduce low-viscosity fluid in I aboveground side low-viscosity region by quick extraction (if low-viscosity fluid is by quick extraction as far as possible, the thickness in low-viscosity region can be made to reduce on the one hand, the viscosity of low-viscosity region inner fluid can be made to increase on the other hand, be unfavorable for that vapor chamber Rapid development is to top); This stage I well is steam injection (generally from short tube steam injection, if need to improve the pressure uniform degree in steam injection amount, the section of improving the standard, can simultaneously from length pipe steam injection) only, and steam injection pressure is higher than reservoir hole pressure and lower than reservoir minimum principal stress; P well is pump under short tube tail end then, and pump extraction oil, maintains the saturated-steam temperature higher than fluid actual temperature (difference is subcool) about 10 DEG C that producing well flowing bottomhole pressure (FBHP) is corresponding; In this later stage in stage, vapor chamber is by Rapid development to top (as shown in Figure 5), and oil production can obviously significantly rise;
2. the low pressure SAGD stage: when the produce oil speed monitoring this well group rises fast, and during apparently higher than the performance of same other well group of block, proceed to low pressure SAGD operation in good time, control the injection pressure of steam close to reservoir hole pressure (be conducive to like this reducing heat waste, improve economy).
Site test results shows: traditional scheme mainly concentrates on quick, the even UNICOM between dual horizontal well, technical scheme provided by the invention can form a vertical dilatation band being full of solvent above horizontal well compared with traditional scheme, and by soaking the vertical low-viscosity region of formation one, after turning SAGD, vapor chamber is grown fast in this low-viscosity region, and fast to top, the fluid column effective height the highest (arrive top) that the crude oil that makes to be heated is formed, the quickening of gravity drainage speed; Meanwhile, compared with traditional scheme, in the technical scheme that the invention provides, steam is larger with the contact area not employing heavy crude reservoir, and heat-transfer effect is better, and economic benefit significantly improves.
Claims (12)
1. improve a method for product speed on the SAGD initial stage, the method comprises the following steps:
Step one, determine the reservoir minimum principal stress of oil reservoir in the horizontal direction;
Step 2, dispose a pair horizontal well in the vertical direction of described oil reservoir, wherein, the horizontal well on vertical direction top is steam injection well, and the horizontal well of vertical direction bottom is producing well;
Step 3, in described producing well and steam injection well, inject liquid phase mixed solvent stage by stage, make described producing well and described gas injection well form inter-well pressure UNICOM, and above described horizontal well, form vertical dilatation band;
In step 4, the dilatation band that described liquid phase mixed solvent entered formed in step 3, soak, in the low-viscosity region that the aboveground square one-tenth of described steam injection is vertical, the viscosity in described low-viscosity region is less than the viscosity of stratum viscous crude;
Step 5, inject steam to described producing well and steam injection well, or inject steam to described producing well separately, carry out cyclic preheat, when described producing well and described steam injection well form Jing Jian heating power UNICOM, stop injecting steam;
Step 6, proceeded to for half SAGD stage, when described producing well and described steam injection well form balanced flood, and when described producing well and described steam injection well are in same pressure system, stop half SAGD operation, proceed to the normal SAGD stage.
2. method according to claim 1, wherein: step at the beginning before, be also included on the well group in territory, same oil Tibetan area and carry out detecting earth stress, test the step of minimum principal stress of the cap rock of same layer position, reservoir, substrate rock stratum respectively.
3. method according to claim 1, wherein: in step 2, the distance bottom described producing well distance oil reservoir is less than 1m;
Preferably, described producing well and described horizontal well distance are in the vertical direction 5m.
4. method according to claim 1, wherein: in step 3, the composition of described liquid phase mixed solvent comprises dimethylbenzene and/or gas-oil, and wherein, described gas-oil is on-the-spot stratum viscous crude through air-distillation, the mixture of boiling point in diesel oil section that extract;
Preferably, the viscosity of described liquid phase mixed solvent is less than 1cP.
5. method according to claim 1, wherein: in step 3, comprises the following steps when injecting liquid phase mixed solvent stage by stage in described producing well and described steam injection well:
A, starting stage: inject liquid phase mixed solvent to improve down-hole pressure to described producing well and described steam injection well simultaneously, in the process improving down-hole pressure, the down-hole pressure reduction between described producing well and described steam injection well is kept to be less than 500kPa, and the injection rate of monitor well downforce and liquid phase mixed solvent;
B, pressure test stage: the down-hole pressure reducing wherein a bite well, maintain that the down-hole pressure of another mouthful of well is constant carries out pressure test, whether exist by the pressure field judging centered by producing well and steam injection well and influence each other, influence each other if existed, stop pressure test, proceed to the operation of step c; Otherwise continue the operation of above-mentioned steps a;
C, crack initiation UNICOM stage: continue the down-hole pressure improving steam injection well, when the down-hole pressure of steam injection well continues to rise, when starting to decline after reaching peak value, the injection flow maintaining liquid phase mixed solvent in steam injection well is constant, maintains near stable pressure fluctuate to make down-hole pressure; Wherein, described peak value is the initial cracking pressure in crack, and described stable pressure is the propagation pressure in crack;
Preferably, improve in the process of down-hole pressure in step a, the hoisting velocity of controlled pressure is within 0.4KPa/h.
6. method according to claim 5, wherein: after step c terminates, the method also comprises the down-hole pressure improving producing well, maintains the step that the down-hole pressure of steam injection well is constant.
7. method according to claim 5, wherein: after step c terminates, the method also comprises the step of carrying out the test of inter-well pressure UNICOM.
8. method according to claim 5, wherein: in step c, when the down-hole pressure of steam injection well continues to rise, after reaching peak value, the method also comprises the step of pressure when taking the mode of closing well to test closing up of cracks, and wherein, pressure during described closing up of cracks is reservoir minimum principal stress.
9. method according to claim 1, wherein: in step 4, in the dilatation band described liquid phase mixed solvent being entered formed in step 3, soak, the low-viscosity region vertical at the aboveground square one-tenth of described steam injection comprises following operating procedure:
Improve the down-hole pressure of described steam injection well, when the reservoir minimum principal stress of described down-hole pressure higher than described oil reservoir, control the actual flow entering the liquid phase mixed solvent of reservoir, guarantee that the down-hole pressure of described steam injection well is less than the cap rock main stress bar of described oil reservoir;
When in described steam injection well, the injection rate of liquid phase solvent reaches preset value, stop injecting, closing well soaks;
Preferably, the time that described closing well soaks is 1 day.
10. method according to claim 9, wherein: in immersion process, the method also comprises monitor well downforce, fills into liquid phase mixed solvent to maintain down-hole pressure, to expand the step of described low-viscosity area thickness.
11. methods according to any one of claim 5-10, wherein: described down-hole pressure is calculated by well head pressure+vertical section head of liquid and obtains;
Preferably, described raising down-hole pressure is by improving clean fluence, namely maintains the injection constant flow of described liquid phase mixed solvent, and that reduces described liquid phase solvent returns that discharge capacity carries out operating.
12. methods according to claim 1, wherein: in step 5, inject steam to described producing well and steam injection well, or when injecting steam to described producing well separately, control the pressure of described steam higher than reservoir hole pressure, and lower than reservoir minimum principal stress;
Preferably, when carrying out cyclic preheat, described preheating time is 1 week.
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| CN201510559419.5A CN105178931B (en) | 2015-09-06 | 2015-09-06 | A kind of method that speed is produced on raising SAGD initial stages |
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| CN107313756A (en) * | 2017-07-04 | 2017-11-03 | 中国石油大学(北京) | The jet connection of SAGD mudstone foundations is made to squeeze sour remodeling method |
| CN108119113A (en) * | 2016-11-30 | 2018-06-05 | 中国石油天然气股份有限公司 | The method of heavy crude producing |
| CN112392472A (en) * | 2019-08-19 | 2021-02-23 | 中国石油天然气股份有限公司 | Method and device for determining integrated development mode of shale and adjacent oil layer |
| CN112443302A (en) * | 2019-08-28 | 2021-03-05 | 中国石油天然气股份有限公司 | SAGD production method |
| CN112746830A (en) * | 2019-10-30 | 2021-05-04 | 中国石油天然气股份有限公司 | Oil reservoir two-stage branch SAGD reservoir deep expansion oil extraction method |
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| CN108119113A (en) * | 2016-11-30 | 2018-06-05 | 中国石油天然气股份有限公司 | The method of heavy crude producing |
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| CN112392472A (en) * | 2019-08-19 | 2021-02-23 | 中国石油天然气股份有限公司 | Method and device for determining integrated development mode of shale and adjacent oil layer |
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| CN112746830A (en) * | 2019-10-30 | 2021-05-04 | 中国石油天然气股份有限公司 | Oil reservoir two-stage branch SAGD reservoir deep expansion oil extraction method |
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| CN105178931B (en) | 2017-11-07 |
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