CA2931882A1 - Method for forced steam cycle preheating dual horizontal well in middle-deep layer reservoir under a constant temperature difference - Google Patents
Method for forced steam cycle preheating dual horizontal well in middle-deep layer reservoir under a constant temperature difference Download PDFInfo
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- 230000009977 dual effect Effects 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000010793 Steam injection (oil industry) Methods 0.000 claims abstract description 84
- 238000004519 manufacturing process Methods 0.000 claims abstract description 65
- 238000002347 injection Methods 0.000 claims abstract description 25
- 239000007924 injection Substances 0.000 claims abstract description 25
- 239000007788 liquid Substances 0.000 claims abstract description 20
- 239000003921 oil Substances 0.000 claims description 49
- 238000010796 Steam-assisted gravity drainage Methods 0.000 claims description 18
- 239000000295 fuel oil Substances 0.000 claims description 16
- 238000012544 monitoring process Methods 0.000 claims description 16
- 230000035699 permeability Effects 0.000 claims description 12
- 238000011161 development Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 238000009529 body temperature measurement Methods 0.000 claims description 7
- 239000013307 optical fiber Substances 0.000 claims description 7
- 239000012530 fluid Substances 0.000 claims description 6
- 238000005086 pumping Methods 0.000 description 13
- 238000004891 communication Methods 0.000 description 12
- 230000008878 coupling Effects 0.000 description 8
- 238000010168 coupling process Methods 0.000 description 8
- 238000005859 coupling reaction Methods 0.000 description 8
- 238000009413 insulation Methods 0.000 description 8
- 238000007789 sealing Methods 0.000 description 8
- 239000010779 crude oil Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000010924 continuous production Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000009421 internal insulation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
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Abstract
A method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, comprising: a step A
of selecting a qualified reservoir; a step B of providing, in the qualified reservoir, dual horizontal wells; a step C of conducting steam huff and puff exploitation in the upper horizontal well and the lower horizontal well at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa; a step D of placing an upper horizontal well steam injection string and an upper horizontal well mechanical lifting string down into the upper horizontal well of the dual horizontal wells, and placing a lower horizontal well steam injection string and a lower horizontal well mechanical lifting string down into the lower horizontal well of the dual horizontal wells; and a step E of conducting cycle preheating, wherein continuous injection and production is performed in the upper horizontal well and the lower horizontal well perform at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile a condensed liquid is extracted by the mechanical lifting, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and a condensed liquid in the lower horizontal well being extracted by the lower horizontal well.
of selecting a qualified reservoir; a step B of providing, in the qualified reservoir, dual horizontal wells; a step C of conducting steam huff and puff exploitation in the upper horizontal well and the lower horizontal well at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa; a step D of placing an upper horizontal well steam injection string and an upper horizontal well mechanical lifting string down into the upper horizontal well of the dual horizontal wells, and placing a lower horizontal well steam injection string and a lower horizontal well mechanical lifting string down into the lower horizontal well of the dual horizontal wells; and a step E of conducting cycle preheating, wherein continuous injection and production is performed in the upper horizontal well and the lower horizontal well perform at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile a condensed liquid is extracted by the mechanical lifting, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and a condensed liquid in the lower horizontal well being extracted by the lower horizontal well.
Description
_ Method for Forced Steam Cycle Preheating Dual Horizontal Well in Middle-Deep Layer Reservoir under a Constant Temperature Difference Technical Field The present invention relates to the field of oil injection and production, and in particular to a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, i.e., a method of realizing an efficient and balanced preheating startup of SAGD (Steam Assisted Gravity Drainage) for dual horizontal wells in a middle-deep layer super heavy-oil reservoir.
Background Art Steam Assisted Gravity Drainage (SAGD) is an effective technical means of exploiting a heavy oil reservoir. As for high viscous crude oil having no flowing capacity under the original conditions of stratum, a preheating phase of the reservoir is necessary so as to realize thermal communication between injection and production wells, and sufficiently preheating the reservoir is the premise of realizing gravity drainage.
In order to establish the thermal communication between dual horizontal wells combined with SAGD injection and producing wells, generally, two preheating manners, i.e., steam huff and puff preheating and steam cycle preheating, are adopted.
The steam huff and puff preheating means that steam huff and puff exploitation is performed simultaneously in the upper and lower horizontal wells, for the purpose of reducing pressure of the stratum and establishing the thermal communication. At the huff and puff preheating stage, it is able to finally cause interwell communication temperature of the horizontal wells to reach 80 C, the pressure to be reduced to about 3 MPa, and the stage production degree can reach 21%. However, the steam huff and puff preheating is incapable of uniformly heating a horizontal section, and with the increase of rounds of huff and puff, a thermal field develops successively, and heterogeneity degree becomes more severe.
Therefore, if the purpose of thermal communication is achieved completely depending on high-pressure huff and puff production, it often causes the horizontal section to be unable to be heated uniformly, which will certainly restrict the production effect after transferring into ....
Background Art Steam Assisted Gravity Drainage (SAGD) is an effective technical means of exploiting a heavy oil reservoir. As for high viscous crude oil having no flowing capacity under the original conditions of stratum, a preheating phase of the reservoir is necessary so as to realize thermal communication between injection and production wells, and sufficiently preheating the reservoir is the premise of realizing gravity drainage.
In order to establish the thermal communication between dual horizontal wells combined with SAGD injection and producing wells, generally, two preheating manners, i.e., steam huff and puff preheating and steam cycle preheating, are adopted.
The steam huff and puff preheating means that steam huff and puff exploitation is performed simultaneously in the upper and lower horizontal wells, for the purpose of reducing pressure of the stratum and establishing the thermal communication. At the huff and puff preheating stage, it is able to finally cause interwell communication temperature of the horizontal wells to reach 80 C, the pressure to be reduced to about 3 MPa, and the stage production degree can reach 21%. However, the steam huff and puff preheating is incapable of uniformly heating a horizontal section, and with the increase of rounds of huff and puff, a thermal field develops successively, and heterogeneity degree becomes more severe.
Therefore, if the purpose of thermal communication is achieved completely depending on high-pressure huff and puff production, it often causes the horizontal section to be unable to be heated uniformly, which will certainly restrict the production effect after transferring into ....
2 ..
SAGD development and thus reduce final recovery ratio.
The cycle preheating refers to that high-temperature steam heats the reservoir without entering the reservoir (or minute quantity of the high-temperature steam entering the reservoir), the steam only cycles in one loop in the horizontal well, which accordingly is called as cycle preheating. Theoretically, after long enough time (two to four months) of steam cycle in the injection and production wells, thermal communication between the injection and production wells can be established, and the horizontal section can be heated uniformly. However, in the practical application, steam self-cycle preheating is realized only in a shallow heavy oil reservoir, and as for a middle-deep layer heavy oil reservoir (600-1000 m), since the steam huff and puff pressure is lower than that of the shallow heavy oil reservoir, for example, pressure of the exploited reservoir is reduced to 3-4 MPa in the steam huff and puff, and in the middle-deep layer heavy oil reservoir, it is difficult for high-temperature hot water to perform self-cycle, the cycle preheating of the middle-deep layer heavy oil reservoir is difficult to realize, which restricts the exploitation of the middle-deep layer heavy oil reservoir.
Summary of the Invention The present invention provides a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, which aims at the problem of cycle preheating of the middle-deep layer heavy oil reservoir, and mainly solves the problem that it is difficult to realize the cycle preheating of the middle-deep heavy oil reservoir.
For this purpose, the present invention provides a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, comprising of:
a step A: selecting a qualified reservoir, geological parameters of which satisfy the following conditions: a buried depth of the reservoir is 600-1000 m, the thickness of the continuous reservoir is more than or equal to 10 m, and a ratio of a vertical permeability to a horizontal permeability is greater than 0.3;
a step B: providing, dual horizontal wells in the qualified reservoir, while the dual horizontal wells comprises an upper horizontal well and a lower horizontal well with a distance of 4-6 m therebetween, wherein a well depth of the dual horizontal wells is less than ....
SAGD development and thus reduce final recovery ratio.
The cycle preheating refers to that high-temperature steam heats the reservoir without entering the reservoir (or minute quantity of the high-temperature steam entering the reservoir), the steam only cycles in one loop in the horizontal well, which accordingly is called as cycle preheating. Theoretically, after long enough time (two to four months) of steam cycle in the injection and production wells, thermal communication between the injection and production wells can be established, and the horizontal section can be heated uniformly. However, in the practical application, steam self-cycle preheating is realized only in a shallow heavy oil reservoir, and as for a middle-deep layer heavy oil reservoir (600-1000 m), since the steam huff and puff pressure is lower than that of the shallow heavy oil reservoir, for example, pressure of the exploited reservoir is reduced to 3-4 MPa in the steam huff and puff, and in the middle-deep layer heavy oil reservoir, it is difficult for high-temperature hot water to perform self-cycle, the cycle preheating of the middle-deep layer heavy oil reservoir is difficult to realize, which restricts the exploitation of the middle-deep layer heavy oil reservoir.
Summary of the Invention The present invention provides a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, which aims at the problem of cycle preheating of the middle-deep layer heavy oil reservoir, and mainly solves the problem that it is difficult to realize the cycle preheating of the middle-deep heavy oil reservoir.
For this purpose, the present invention provides a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, comprising of:
a step A: selecting a qualified reservoir, geological parameters of which satisfy the following conditions: a buried depth of the reservoir is 600-1000 m, the thickness of the continuous reservoir is more than or equal to 10 m, and a ratio of a vertical permeability to a horizontal permeability is greater than 0.3;
a step B: providing, dual horizontal wells in the qualified reservoir, while the dual horizontal wells comprises an upper horizontal well and a lower horizontal well with a distance of 4-6 m therebetween, wherein a well depth of the dual horizontal wells is less than ....
3 ..
1600 m, and the length of horizontal sections of the dual horizontal wells is more than or equal to 300 m;
a step C: conducting steam huff and puff exploitation in the upper horizontal well and the lower horizontal well at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa;
a step D: then, placing an upper horizontal well steam injection string and an upper horizontal well mechanical lifting string down into the upper horizontal well of the dual horizontal wells, such that the upper horizontal well steam injection string extends to a position at 2/3 of the horizontal section of the upper horizontal well, and placing a lower horizontal well steam injection string and a lower horizontal well mechanical lifting string down into the lower horizontal well of the dual horizontal wells, such that the lower horizontal well steam injection string extends to a tiptoe of the horizontal section of the lower horizontal well; and a step E: then conducting cycle preheating, wherein continuous injection and production is performed in the upper horizontal well and the lower horizontal well at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile a condensed liquid is extracted by the mechanical lifting, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and the condensed liquid in the lower horizontal well being extracted by the lower horizontal well.
Further, the method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference further comprises a step F : after the cycle preheating lasts for two to four months, transferring to Steam Assisted Gravity Drainage development, in which the steam is injected by a steam injection well, and a production well is depressurized for production, wherein the upper horizontal well is the steam injection well and the lower horizontal well is the production well.
Further, in the step C, the steam huff and puff exploitation is performed in the upper horizontal well and the lower horizontal well at the same time, such that the reservoir is depressurized to 3 to 3.5 MPa.
Further, super heavy oil in a reservoir block of the qualified reservoir has fluid characteristics as follows: degassed oil viscosity under reservoir temperature is more than 50000 mPais, and relative density is more than 0.98 g/cm3.
Further, the step F specifically comprises transferring to the Steam Assisted Gravity Drainage development or continuously injecting the steam by the steam injection well and - .
1600 m, and the length of horizontal sections of the dual horizontal wells is more than or equal to 300 m;
a step C: conducting steam huff and puff exploitation in the upper horizontal well and the lower horizontal well at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa;
a step D: then, placing an upper horizontal well steam injection string and an upper horizontal well mechanical lifting string down into the upper horizontal well of the dual horizontal wells, such that the upper horizontal well steam injection string extends to a position at 2/3 of the horizontal section of the upper horizontal well, and placing a lower horizontal well steam injection string and a lower horizontal well mechanical lifting string down into the lower horizontal well of the dual horizontal wells, such that the lower horizontal well steam injection string extends to a tiptoe of the horizontal section of the lower horizontal well; and a step E: then conducting cycle preheating, wherein continuous injection and production is performed in the upper horizontal well and the lower horizontal well at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile a condensed liquid is extracted by the mechanical lifting, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and the condensed liquid in the lower horizontal well being extracted by the lower horizontal well.
Further, the method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference further comprises a step F : after the cycle preheating lasts for two to four months, transferring to Steam Assisted Gravity Drainage development, in which the steam is injected by a steam injection well, and a production well is depressurized for production, wherein the upper horizontal well is the steam injection well and the lower horizontal well is the production well.
Further, in the step C, the steam huff and puff exploitation is performed in the upper horizontal well and the lower horizontal well at the same time, such that the reservoir is depressurized to 3 to 3.5 MPa.
Further, super heavy oil in a reservoir block of the qualified reservoir has fluid characteristics as follows: degassed oil viscosity under reservoir temperature is more than 50000 mPais, and relative density is more than 0.98 g/cm3.
Further, the step F specifically comprises transferring to the Steam Assisted Gravity Drainage development or continuously injecting the steam by the steam injection well and - .
4 ..
conducting continuous production by the production well, when temperature between the steam injection well and the production well is higher than 90 C, and temperature of more than 80% of the horizontal sections of the steam injection well and the production well reaches 150 C.
Further, the step A specifically comprises a step Al of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: the buried depth of the reservoir is 995 m, degassed oil viscosity under 50 C is 53450-72340 mPa.s, and the thickness of the continuous reservoir is equal to 15 m;
The step B specifically comprises a step B1 of providing, in the qualified reservoir, two pairs of dual horizontal wells, each pair including an upper horizontal well and a lower horizontal well with a distance of 5 m therebetween;
The step E specifically comprises a step El in which a working steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t;
and The step F specifically comprises a step Fl of conducting the cycle preheating for four months, a production-injection ratio being between 0.8 to 1.2.
Further, the step D further comprises a step DI in which the upper horizontal well is used as a monitoring well and an optical fiber temperature measurement system is placed down into the upper horizontal well.
Further, through forced circulation by the mechanical lifting, the steam is not simulated to enter the reservoir; heat is transferred mainly in the manner of heat conduction, and the stratum is heated depending only on the manner of heat conduction caused by temperature difference between the temperature of the steam and that of the stratum; the extracted liquid is the condensed water formed after the injected steam is cooled, with the production-injection ratio being maintained at 1Ø
Further, the step A specifically comprises a step A2 of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: the buried depth of the reservoir is 680 m, degassed oil viscosity under 50 C is 147500¨'485400 mPa.s, and the thickness of the continuous reservoir is equal to 80 m.
The upper horizontal well mechanical lifting string is disposed at an angle building section of the upper horizontal well, and the lower horizontal well mechanical lifting string is disposed at an angle building section of the lower horizontal well.
Compared to a traditional cycle preheating manner for the middle-deep layer reservoir, the present invention places mechanical lifting strings down into the dual horizontal wells before the cycle preheating, so as to be able to lift and extract high-temperature hot water by - .
..
mechanical lifting of the mechanical lifting strings in the process of cycle preheating, and force the steam to circulate to achieve uniform heating under a constant temperature difference of the same reservoir, thereby overcoming the defect that it is difficult to realize cycle preheating in the middle-deep reservoir by the traditional cycle preheating manner.
conducting continuous production by the production well, when temperature between the steam injection well and the production well is higher than 90 C, and temperature of more than 80% of the horizontal sections of the steam injection well and the production well reaches 150 C.
Further, the step A specifically comprises a step Al of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: the buried depth of the reservoir is 995 m, degassed oil viscosity under 50 C is 53450-72340 mPa.s, and the thickness of the continuous reservoir is equal to 15 m;
The step B specifically comprises a step B1 of providing, in the qualified reservoir, two pairs of dual horizontal wells, each pair including an upper horizontal well and a lower horizontal well with a distance of 5 m therebetween;
The step E specifically comprises a step El in which a working steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t;
and The step F specifically comprises a step Fl of conducting the cycle preheating for four months, a production-injection ratio being between 0.8 to 1.2.
Further, the step D further comprises a step DI in which the upper horizontal well is used as a monitoring well and an optical fiber temperature measurement system is placed down into the upper horizontal well.
Further, through forced circulation by the mechanical lifting, the steam is not simulated to enter the reservoir; heat is transferred mainly in the manner of heat conduction, and the stratum is heated depending only on the manner of heat conduction caused by temperature difference between the temperature of the steam and that of the stratum; the extracted liquid is the condensed water formed after the injected steam is cooled, with the production-injection ratio being maintained at 1Ø
Further, the step A specifically comprises a step A2 of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: the buried depth of the reservoir is 680 m, degassed oil viscosity under 50 C is 147500¨'485400 mPa.s, and the thickness of the continuous reservoir is equal to 80 m.
The upper horizontal well mechanical lifting string is disposed at an angle building section of the upper horizontal well, and the lower horizontal well mechanical lifting string is disposed at an angle building section of the lower horizontal well.
Compared to a traditional cycle preheating manner for the middle-deep layer reservoir, the present invention places mechanical lifting strings down into the dual horizontal wells before the cycle preheating, so as to be able to lift and extract high-temperature hot water by - .
..
mechanical lifting of the mechanical lifting strings in the process of cycle preheating, and force the steam to circulate to achieve uniform heating under a constant temperature difference of the same reservoir, thereby overcoming the defect that it is difficult to realize cycle preheating in the middle-deep reservoir by the traditional cycle preheating manner.
5 Brief Description of the Drawings FIG. 1 is a schematic view showing the working principle of a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to an embodiment of the present invention;
FIG. 2 is a front schematic cross-sectional view showing the structure of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure according to the embodiment of the present invention;
FIG. 3 is a front schematic cross-sectional view showing the structure of a wellhead valve system of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure according to the embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view in a horizontal direction showing the structure of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure which pipes are located in a vertical section of an intermediate casing according to the embodiment of the present invention;
FIG. 5 is a schematic cross-sectional view in a vertical direction showing the structure of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure which pipes are located in a horizontal section of an intermediate casing according to the embodiment of the present invention; and FIG. 6 is a schematic cross-sectional view (in a side view direction) showing the structure of an integral joint tubing hanger of a wellhead valve system of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure according to the embodiment of the present invention.
List of reference signs:
1. upper horizontal well; 10. horizontal section; 13. angle building section;
15. upper ..
FIG. 2 is a front schematic cross-sectional view showing the structure of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure according to the embodiment of the present invention;
FIG. 3 is a front schematic cross-sectional view showing the structure of a wellhead valve system of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure according to the embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view in a horizontal direction showing the structure of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure which pipes are located in a vertical section of an intermediate casing according to the embodiment of the present invention;
FIG. 5 is a schematic cross-sectional view in a vertical direction showing the structure of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure which pipes are located in a horizontal section of an intermediate casing according to the embodiment of the present invention; and FIG. 6 is a schematic cross-sectional view (in a side view direction) showing the structure of an integral joint tubing hanger of a wellhead valve system of an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure according to the embodiment of the present invention.
List of reference signs:
1. upper horizontal well; 10. horizontal section; 13. angle building section;
15. upper ..
6 ..
horizontal well mechanical lifting string; 17. upper horizontal well steam injection string 3. lower horizontal well; 30. horizontal section; 33. angle building section;
35. lower horizontal well mechanical lifting string; 17. lower horizontal well steam injection string 101. intermediate casing; 102. steam injection string; 103. mechanical lifting string; 104.
oil pumping pump; 105. tail end screen; 106. screen pipe hanger of the horizontal well; 107.
vertical section of the steam injection string; 108. horizontal section of the steam injection string; 109. integral joint tubing; 110. continuous tubing; 202. steam inlet;
203. casing annulus inlet and outlet; 204. polish rod; 205. polish rod sealer; 206. rubber gate;
207. remote hydraulic sealer; 208. integral joint tubing hanger; 209. thick flange sealing body; 304:
pumping pipe coupling; 305: thermal insulation pipe; 306. thermal insulation layer; 307.
thermal insulation inner pipe Detailed Description of the Embodiments In order to more clearly understand technical features, objects and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.
As shown in FIG 1, the present invention provides a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, comprising of:
a step A: selecting a qualified reservoir, and confirming the feasibility of implementing the present invention according to known geological parameters of the reservoir and fluid characteristics of super heavy oil, wherein the geological parameters of the qualified reservoir of the present invention satisfy the following conditions: the middle-deep layer reservoir has a buried depth of the reservoir of 600-1000 m, the thickness of the continuous reservoir is more than or equal to 10 m, a ratio of a vertical permeability to a horizontal permeability is greater than 0.3, and wherein the present invention is aimed at a middle-deep layer reservoir with a buried depth of the reservoir being 600-1000 m, because preheating a shallow reservoir does not need the process method of the present invention, and a too deep reservoir needs a more complicated process and equipment;
a step B: providing, in the qualified reservoir, dual horizontal wells which comprises an upper horizontal well 1 and a lower horizontal well 3 with a distance of 4-6 m therebetween, wherein a well depth of the dual horizontal wells is less than 1600 m, and the length of respective horizontal sections of the dual horizontal wells is more than or equal to 300 m, and wherein the arrangement of the dual horizontal wells and their parameters ensue the
horizontal well mechanical lifting string; 17. upper horizontal well steam injection string 3. lower horizontal well; 30. horizontal section; 33. angle building section;
35. lower horizontal well mechanical lifting string; 17. lower horizontal well steam injection string 101. intermediate casing; 102. steam injection string; 103. mechanical lifting string; 104.
oil pumping pump; 105. tail end screen; 106. screen pipe hanger of the horizontal well; 107.
vertical section of the steam injection string; 108. horizontal section of the steam injection string; 109. integral joint tubing; 110. continuous tubing; 202. steam inlet;
203. casing annulus inlet and outlet; 204. polish rod; 205. polish rod sealer; 206. rubber gate;
207. remote hydraulic sealer; 208. integral joint tubing hanger; 209. thick flange sealing body; 304:
pumping pipe coupling; 305: thermal insulation pipe; 306. thermal insulation layer; 307.
thermal insulation inner pipe Detailed Description of the Embodiments In order to more clearly understand technical features, objects and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.
As shown in FIG 1, the present invention provides a method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, comprising of:
a step A: selecting a qualified reservoir, and confirming the feasibility of implementing the present invention according to known geological parameters of the reservoir and fluid characteristics of super heavy oil, wherein the geological parameters of the qualified reservoir of the present invention satisfy the following conditions: the middle-deep layer reservoir has a buried depth of the reservoir of 600-1000 m, the thickness of the continuous reservoir is more than or equal to 10 m, a ratio of a vertical permeability to a horizontal permeability is greater than 0.3, and wherein the present invention is aimed at a middle-deep layer reservoir with a buried depth of the reservoir being 600-1000 m, because preheating a shallow reservoir does not need the process method of the present invention, and a too deep reservoir needs a more complicated process and equipment;
a step B: providing, in the qualified reservoir, dual horizontal wells which comprises an upper horizontal well 1 and a lower horizontal well 3 with a distance of 4-6 m therebetween, wherein a well depth of the dual horizontal wells is less than 1600 m, and the length of respective horizontal sections of the dual horizontal wells is more than or equal to 300 m, and wherein the arrangement of the dual horizontal wells and their parameters ensue the
7 subsequent cycle preheating;
a step C: conducting steam huff and puff exploitation simultaneously on the upper horizontal well 1 and the lower horizontal well 3 at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa, so as to prepare pressure and temperature conditions for the subsequent cycle preheating, for example, by conducting steam huff and puff exploitation by placing down a string for steam huff and puff exploitation, and then lifting the string for steam huff and puff exploitation out after the qualified reservoir is depressurized to below 3.5 MPa;
a step D: after the qualified reservoir is depressurized to below 3.5 MPa, placing down an upper horizontal well steam injection string 17 and an upper horizontal well mechanical lifting string 15 into the upper horizontal well 1 of the dual horizontal wells, so that the upper horizontal well steam injection string 17 extends to a position at 2/3 of the horizontal section 10 of the upper horizontal well, i.e., at a distance of 1/3 of length of the horizontal section 10 of the upper horizontal well from a tail end of the horizontal section 10 of the upper horizontal well, and placing down a lower horizontal well steam injection string 37 and a lower horizontal well mechanical lifting string 35 into the lower horizontal well 3 of the dual horizontal wells, so that the lower horizontal well steam injection string 37 extends to a tiptoe of the horizontal section 30 of the lower horizontal well, wherein the upper horizontal well mechanical lifting string 15 is disposed at an angle building section 13 or a heel of the upper horizontal well, and the lower horizontal well mechanical lifting string 35 is disposed at an angle building section 33 or a heel of the lower horizontal well; the above-described parameters are set by taking into consideration thermal communication between horizontal wells and a preheating effect of the overall horizontal section of the upper horizontal well and a preheating effect of the overall horizontal section of the lower horizontal well, to ensure the condensed liquid in the horizontal wells to be forced to circulate;
a step E: then conducting cycle preheating, including performing continuous injection and production in the upper horizontal well and the lower horizontal well at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile a condensed liquid is extracted by the mechanical lifting, i.e., high-temperature steam is condensed into the condensed liquid after going down into the well from the wellhead, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and the condensed liquid in the lower horizontal well being extracted by the lower horizontal well, and wherein the steam enters and outlets from the well to form a complete cycle, so as to achieve the purpose of cycle preheating the middle-deep layer
a step C: conducting steam huff and puff exploitation simultaneously on the upper horizontal well 1 and the lower horizontal well 3 at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa, so as to prepare pressure and temperature conditions for the subsequent cycle preheating, for example, by conducting steam huff and puff exploitation by placing down a string for steam huff and puff exploitation, and then lifting the string for steam huff and puff exploitation out after the qualified reservoir is depressurized to below 3.5 MPa;
a step D: after the qualified reservoir is depressurized to below 3.5 MPa, placing down an upper horizontal well steam injection string 17 and an upper horizontal well mechanical lifting string 15 into the upper horizontal well 1 of the dual horizontal wells, so that the upper horizontal well steam injection string 17 extends to a position at 2/3 of the horizontal section 10 of the upper horizontal well, i.e., at a distance of 1/3 of length of the horizontal section 10 of the upper horizontal well from a tail end of the horizontal section 10 of the upper horizontal well, and placing down a lower horizontal well steam injection string 37 and a lower horizontal well mechanical lifting string 35 into the lower horizontal well 3 of the dual horizontal wells, so that the lower horizontal well steam injection string 37 extends to a tiptoe of the horizontal section 30 of the lower horizontal well, wherein the upper horizontal well mechanical lifting string 15 is disposed at an angle building section 13 or a heel of the upper horizontal well, and the lower horizontal well mechanical lifting string 35 is disposed at an angle building section 33 or a heel of the lower horizontal well; the above-described parameters are set by taking into consideration thermal communication between horizontal wells and a preheating effect of the overall horizontal section of the upper horizontal well and a preheating effect of the overall horizontal section of the lower horizontal well, to ensure the condensed liquid in the horizontal wells to be forced to circulate;
a step E: then conducting cycle preheating, including performing continuous injection and production in the upper horizontal well and the lower horizontal well at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile a condensed liquid is extracted by the mechanical lifting, i.e., high-temperature steam is condensed into the condensed liquid after going down into the well from the wellhead, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and the condensed liquid in the lower horizontal well being extracted by the lower horizontal well, and wherein the steam enters and outlets from the well to form a complete cycle, so as to achieve the purpose of cycle preheating the middle-deep layer
8 , .
reservoir.
By providing the dual horizontal wells, providing the mechanical lifting strings in the dual horizontal wells, and selecting suitable process parameters, it is possible to realize the forced steam circulation in the dual horizontal wells of the middle-deep layer reservoir and to realize uniform heating under a constant temperature difference, so that the reservoir between the dual horizontal wells has been sufficiently preheated and reached the thermal communication condition.
Further, the method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference also comprises a step F
of, after the cycle preheating lasts for two to four months, transferring to Steam Assisted Gravity Drainage development in which the steam is injected by a steam injection well, and a production well is depressurized for production, wherein the upper horizontal well is the steam injection well and the lower horizontal well is the production well, so as to allow a reservoir fluid to enter the production well, perform continuous production by mechanical lifting and realize gravity drainage development.
Further, in the step C, the steam huff and puff exploitation is performed simultaneously in the upper horizontal well and the lower horizontal well, such that the reservoir is depressurized to 3 to 3.5 MPa. This is because it is not advantageous for the lifting of high-temperature water or the condensed liquid that the pressure is reduced too much.
Further, a super heavy oil in a reservoir block of the qualified reservoir has fluid characteristics as follows: degassed oil viscosity under reservoir temperature is more than 50000 mPa.s, and relative density is more than 0.98 g/cm3. These parameters are suitable for the lifting and preheating process of the present invention.
Further, the step F specifically comprises: then transferring to the Steam Assisted Gravity Drainage development, in which the steam injection well is used for injecting the steam continuously and the production well is used for conducting continuous production, when the temperature of the reservoir between the steam injection well and the production well is higher than 90 C, and the temperature of more than 80% of the horizontal sections of the injection well and the production well reaches 150 C so that the reservoir between the injection and production wells has been sufficiently preheated and reached the thermal communication condition, .
Further, the step A specifically comprises a step Al of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: a buried depth of the reservoir is 995 m, degassed oil viscosity under 50 C is 53450-72340 mPa.s, and continuous ,
reservoir.
By providing the dual horizontal wells, providing the mechanical lifting strings in the dual horizontal wells, and selecting suitable process parameters, it is possible to realize the forced steam circulation in the dual horizontal wells of the middle-deep layer reservoir and to realize uniform heating under a constant temperature difference, so that the reservoir between the dual horizontal wells has been sufficiently preheated and reached the thermal communication condition.
Further, the method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference also comprises a step F
of, after the cycle preheating lasts for two to four months, transferring to Steam Assisted Gravity Drainage development in which the steam is injected by a steam injection well, and a production well is depressurized for production, wherein the upper horizontal well is the steam injection well and the lower horizontal well is the production well, so as to allow a reservoir fluid to enter the production well, perform continuous production by mechanical lifting and realize gravity drainage development.
Further, in the step C, the steam huff and puff exploitation is performed simultaneously in the upper horizontal well and the lower horizontal well, such that the reservoir is depressurized to 3 to 3.5 MPa. This is because it is not advantageous for the lifting of high-temperature water or the condensed liquid that the pressure is reduced too much.
Further, a super heavy oil in a reservoir block of the qualified reservoir has fluid characteristics as follows: degassed oil viscosity under reservoir temperature is more than 50000 mPa.s, and relative density is more than 0.98 g/cm3. These parameters are suitable for the lifting and preheating process of the present invention.
Further, the step F specifically comprises: then transferring to the Steam Assisted Gravity Drainage development, in which the steam injection well is used for injecting the steam continuously and the production well is used for conducting continuous production, when the temperature of the reservoir between the steam injection well and the production well is higher than 90 C, and the temperature of more than 80% of the horizontal sections of the injection well and the production well reaches 150 C so that the reservoir between the injection and production wells has been sufficiently preheated and reached the thermal communication condition, .
Further, the step A specifically comprises a step Al of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: a buried depth of the reservoir is 995 m, degassed oil viscosity under 50 C is 53450-72340 mPa.s, and continuous ,
9 reservoir thickness is equal to 15 m;
The step B specifically comprises a step B1 of providing, in the qualified reservoir, two pairs of dual horizontal wells, each pair including an upper horizontal well and a lower horizontal well with a distance of 5 m therebetween. In this way, efficiency and production can be improved;
The step E specifically comprises a step El in which a working steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t.
These parameters are advantageous for the reservoir between the injection and production wells to have been sufficiently preheated and reached the thermal communication condition.
The step F specifically comprises a step F 1 of conducting cycle preheating for four months to realize sufficient preheating, a production-injection ratio being between 0.8 and 1.2 to realize continuous cycle, and preferably, the production-injection ratio being 1, so that the cycle is relative ideal.
Further, the step D also comprises a step D1 of using the upper horizontal well as a monitoring well and placing an optical fiber temperature measurement system down into the upper horizontal well, for detecting downhole temperature. It has been shown from optical fiber temperature monitoring data for the upper horizontal well that, after the steam is injected into the lower horizontal well, temperature of the horizontal section rises gradually, a section of the well in thermal communication is long, and this shows that two wells are gradually communicated with each other.
For example, when the upper horizontal well serves as the monitoring well, the present invention adopts an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure in the following embodiment, to place down a steam injection string 102, a mechanical lifting string 103 and a continuous tubing at the same time, the continuous tubing is provided therein with an optical fiber temperature measurement system which comprises e.g., a capillary and multiple sets of thermocouple to realize organic combination of steam injection, lifting and temperature measurement in the same shaft, and the above-described three functions can be realized in the same shaft.
As shown in FIG. 2, the oil production process equipment having three pipes within the same shaft comprises: a wellhead valve system, a steam injection string 102, a mechanical lifting string 103, and an integral joint tubing 109.
An intermediate casing 101 is provided in the shaft of the horizontal well and comprises a vertical section of the intermediate casing and a horizontal section of the intermediate casing . .
, .
that are connected to each other; in a preferable embodiment, an inner diameter of the vertical section of the intermediate casing 101 is equal to or more than 220 mm, and an inner diameter of the horizontal section of the intermediate casing is equal to or more than 178 mm.
As shown in FIG. 3, the wellhead valve system is disposed at a wellhead of the shaft of 5 the horizontal well or at the ground, and is connected with the intermediate casing 101;
The steam injection string 102, the mechanical lifting string 103, and the integral joint tubing 109 are disposed in the intermediate tubing 101 respectively, as shown in FIGs. 4 and 5, and the steam injection string 102, the mechanical lifting string 103, and the integral joint tubing 109 are not contained within one another, or are not in built-in relationship, i.e. any one
The step B specifically comprises a step B1 of providing, in the qualified reservoir, two pairs of dual horizontal wells, each pair including an upper horizontal well and a lower horizontal well with a distance of 5 m therebetween. In this way, efficiency and production can be improved;
The step E specifically comprises a step El in which a working steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t.
These parameters are advantageous for the reservoir between the injection and production wells to have been sufficiently preheated and reached the thermal communication condition.
The step F specifically comprises a step F 1 of conducting cycle preheating for four months to realize sufficient preheating, a production-injection ratio being between 0.8 and 1.2 to realize continuous cycle, and preferably, the production-injection ratio being 1, so that the cycle is relative ideal.
Further, the step D also comprises a step D1 of using the upper horizontal well as a monitoring well and placing an optical fiber temperature measurement system down into the upper horizontal well, for detecting downhole temperature. It has been shown from optical fiber temperature monitoring data for the upper horizontal well that, after the steam is injected into the lower horizontal well, temperature of the horizontal section rises gradually, a section of the well in thermal communication is long, and this shows that two wells are gradually communicated with each other.
For example, when the upper horizontal well serves as the monitoring well, the present invention adopts an oil production process equipment having three pipes within the same shaft for steam injection into the horizontal well, oil production and real-time monitoring of temperature and pressure in the following embodiment, to place down a steam injection string 102, a mechanical lifting string 103 and a continuous tubing at the same time, the continuous tubing is provided therein with an optical fiber temperature measurement system which comprises e.g., a capillary and multiple sets of thermocouple to realize organic combination of steam injection, lifting and temperature measurement in the same shaft, and the above-described three functions can be realized in the same shaft.
As shown in FIG. 2, the oil production process equipment having three pipes within the same shaft comprises: a wellhead valve system, a steam injection string 102, a mechanical lifting string 103, and an integral joint tubing 109.
An intermediate casing 101 is provided in the shaft of the horizontal well and comprises a vertical section of the intermediate casing and a horizontal section of the intermediate casing . .
, .
that are connected to each other; in a preferable embodiment, an inner diameter of the vertical section of the intermediate casing 101 is equal to or more than 220 mm, and an inner diameter of the horizontal section of the intermediate casing is equal to or more than 178 mm.
As shown in FIG. 3, the wellhead valve system is disposed at a wellhead of the shaft of 5 the horizontal well or at the ground, and is connected with the intermediate casing 101;
The steam injection string 102, the mechanical lifting string 103, and the integral joint tubing 109 are disposed in the intermediate tubing 101 respectively, as shown in FIGs. 4 and 5, and the steam injection string 102, the mechanical lifting string 103, and the integral joint tubing 109 are not contained within one another, or are not in built-in relationship, i.e. any one
10 of the three strings or tubing is disposed outside the other two;
The integral joint tubing 109 comprises a vertical section of the integral joint tubing and a horizontal section of the integral joint tubing that are connected to each other, the vertical section of the integral joint tubing being positioned in the vertical section of the intermediate casing, the horizontal section of the integral joint tubing being positioned in the horizontal section of the intermediate casing, and a tail end of the integral joint tubing being positioned in front of a steam outlet of the steam injection string, for protecting the continuous temperature-pressure monitoring tubing;
As shown in FIGs. 4 and 5, the continuous tubing 110 disposed in the integral joint tubing 109 is provided therein with a capillary and multiple sets of thermocouples, and comprises a vertical section of the continuous tubing and a horizontal section of the continuous tubing that are connected to each other, the vertical section of the continuous tubing being positioned in the vertical section of the integral joint tubing, the horizontal section of the continuous tubing being positioned in the horizontal section of the integral joint tubing, and a tail end of the continuous tubing substantially corresponding to that of the integral joint tubing, for filling the capillary to measure pressure and the thermocouples to measure temperature; the capillary shall have a testing pressure of less than 15 MPa, and the multiple sets of thermocouples shall have a testing temperature of lower than 450 C, and heat-resistant protective materials are filled between the capillary, the multiple sets of thermocouple and the continuous tubing;
The steam injection string 102 comprises a vertical section 107 of the steam injection string and a horizontal section 108 of the steam injection string that are connected to each other, the vertical section of the steam injection string being positioned in the vertical section of the intermediate casing, the horizontal section of the steam injection string being positioned in the horizontal section of the intermediate casing, and the steam being injected from the tail -
The integral joint tubing 109 comprises a vertical section of the integral joint tubing and a horizontal section of the integral joint tubing that are connected to each other, the vertical section of the integral joint tubing being positioned in the vertical section of the intermediate casing, the horizontal section of the integral joint tubing being positioned in the horizontal section of the intermediate casing, and a tail end of the integral joint tubing being positioned in front of a steam outlet of the steam injection string, for protecting the continuous temperature-pressure monitoring tubing;
As shown in FIGs. 4 and 5, the continuous tubing 110 disposed in the integral joint tubing 109 is provided therein with a capillary and multiple sets of thermocouples, and comprises a vertical section of the continuous tubing and a horizontal section of the continuous tubing that are connected to each other, the vertical section of the continuous tubing being positioned in the vertical section of the integral joint tubing, the horizontal section of the continuous tubing being positioned in the horizontal section of the integral joint tubing, and a tail end of the continuous tubing substantially corresponding to that of the integral joint tubing, for filling the capillary to measure pressure and the thermocouples to measure temperature; the capillary shall have a testing pressure of less than 15 MPa, and the multiple sets of thermocouples shall have a testing temperature of lower than 450 C, and heat-resistant protective materials are filled between the capillary, the multiple sets of thermocouple and the continuous tubing;
The steam injection string 102 comprises a vertical section 107 of the steam injection string and a horizontal section 108 of the steam injection string that are connected to each other, the vertical section of the steam injection string being positioned in the vertical section of the intermediate casing, the horizontal section of the steam injection string being positioned in the horizontal section of the intermediate casing, and the steam being injected from the tail -
11 . , end of the steam injection string to the shaft of the horizontal well to realize crude oil exploitation and preheating of the reservoir; as shown in FIGs. 4 and 5, the steam injection string includes from outside to inside as follows: a thermal insulation outer pipe 305, a thermal insulation layer 306 and a thermal insulation inner pipe 307, wherein the thermal insulation layer 306 is interposed between the thermal insulation outer pipe 305 and the internal insulation inner pipe 307;
The mechanical lifting string 103 is disposed in the vertical section of the intermediate cashing, for lifting liquid (crude oil) in the shaft; as shown in FIG 5, the mechanical lifting string 103 includes oil pumping pipes that are connected by a pumping pipe coupling 304;
As shown in FIG. 6, the wellhead valve system includes a thick flange sealing body 209, an integral joint tubing hanger 208, a pumping pipe outlet 201, and a steam inlet 202 (as shown in FIG. 3), wherein the steam inlet 202 is disposed on the thick flange sealing body 209.
The integral joint tubing 109 and the continuous tubing 110 are hung from the integral joint tubing hanger 208, the mechanical lifting string 103 is connected with the pumping pipe outlet 201, and the steam injection string 102 is connected with the steam inlet 202. As shown in FIG. 6, the integral joint tubing hanger 208 is disposed on the thick flange sealing body 209, and the integral joint tubing hanger 208 contains a signal receiving system for converting the signal received in the continuous tubing 110 into temperature and pressure data.
Moreover, as shown in FIG. 3, the wellhead valve system further comprises a casing annulus inlet and outlet 203, a polish rod 204, a polish rod sealer 205, a rubber gate 206, and a remote hydraulic sealer 207.
Besides three strings or pipes disposed within the shaft at the same time, the present invention further differs obviously from an existing wellhead equipment at the wellhead. One main difference is that: in the present invention, the wellhead valve system is further provided at the wellhead with components for connecting or hanging the three strings or pipes, the mechanical lifting string being connected with the pumping pipe outlet 201, the steam injection string 102 being connected with the steam inlet 202, and the integral joint tubing 109 and the continuous tubing 110 being hung from the integral joint tubing hanger 208. That is to say, both the steam injection string and the mechanical lifting string are hung directly from the thick flange sealing body 209, the thick flange sealing body 209 being the original tubing hanger at the wellhead, which is the same as the prior art; however, besides this, in the present invention, the integral joint tubing hanger 208 is hung from the thick flange sealing body 209, for fixing and connecting the continuous tubing 110.
The mechanical lifting string 103 is disposed in the vertical section of the intermediate cashing, for lifting liquid (crude oil) in the shaft; as shown in FIG 5, the mechanical lifting string 103 includes oil pumping pipes that are connected by a pumping pipe coupling 304;
As shown in FIG. 6, the wellhead valve system includes a thick flange sealing body 209, an integral joint tubing hanger 208, a pumping pipe outlet 201, and a steam inlet 202 (as shown in FIG. 3), wherein the steam inlet 202 is disposed on the thick flange sealing body 209.
The integral joint tubing 109 and the continuous tubing 110 are hung from the integral joint tubing hanger 208, the mechanical lifting string 103 is connected with the pumping pipe outlet 201, and the steam injection string 102 is connected with the steam inlet 202. As shown in FIG. 6, the integral joint tubing hanger 208 is disposed on the thick flange sealing body 209, and the integral joint tubing hanger 208 contains a signal receiving system for converting the signal received in the continuous tubing 110 into temperature and pressure data.
Moreover, as shown in FIG. 3, the wellhead valve system further comprises a casing annulus inlet and outlet 203, a polish rod 204, a polish rod sealer 205, a rubber gate 206, and a remote hydraulic sealer 207.
Besides three strings or pipes disposed within the shaft at the same time, the present invention further differs obviously from an existing wellhead equipment at the wellhead. One main difference is that: in the present invention, the wellhead valve system is further provided at the wellhead with components for connecting or hanging the three strings or pipes, the mechanical lifting string being connected with the pumping pipe outlet 201, the steam injection string 102 being connected with the steam inlet 202, and the integral joint tubing 109 and the continuous tubing 110 being hung from the integral joint tubing hanger 208. That is to say, both the steam injection string and the mechanical lifting string are hung directly from the thick flange sealing body 209, the thick flange sealing body 209 being the original tubing hanger at the wellhead, which is the same as the prior art; however, besides this, in the present invention, the integral joint tubing hanger 208 is hung from the thick flange sealing body 209, for fixing and connecting the continuous tubing 110.
12 In order to ensure that three strings or pipes all can be connected or hung in the limited space of the wellhead valve system, in the present invention, besides the steam inlet 202 disposed on the thick flange sealing body 209, a space for disposing the integral joint tubing hanger 208 is further provided, so that the steam inlet 202 and the integral joint tubing hanger 208 do not affect each other or intervene with each other; the integral joint tubing hanger 208 is disposed at the side of the steam inlet 202, and it can be seen from FIG 3 that the integral joint tubing hanger 208 is disposed behind the steam inlet 202.
The present invention achieves steam injection, oil production and monitoring within the same shaft, so that steam injection, oil production and monitoring can be conducted within the same shaft at the same time, while the prior art only relates to steam injection and monitoring for huff and puff exploitation, and it is necessary to lift the steam injection and monitoring string out after the steam injection ends, and to place down a production string to conduct the oil production.
Further, as shown in FIG. 2, the oil production process equipment having three pipes within the same shaft also comprises an oil pumping pump 104 connected at a bottom end of the mechanical lifting string 103, for pumping steam condensed water in the horizontal well and crude oil doped in the steam condensed water. A piston of the oil pumping pump is connected with a sucker rod by a sucker rod releasing-connecting device. The depth L for which the oil pumping pump is placed down satisfies:
L>H-100(P-1) wherein, H is vertical depth of the reservoir, and P is stratum pressure.
Further, as shown in FIG. 2, the oil production process equipment having three pipes within the same shaft also comprises a horizontal well screen pipe hanger 106 disposed in the intermediate cashing, for hanging a screen pipe of the horizontal section of the horizontal well; a tail end screen 105 is located at a tail end of the screen pipe, for injecting steam into the horizontal section of the intermediate cashing.
Further, as shown in FIG 5, the sum of maximum outer diameters of the steam injection string, the mechanical lifting string, and the integral joint tubing is at least 10 mm less than an inner diameter of the vertical section of the intermediate cashing, to ensure that three strings or pipes all can be installed in the intermediate cashing. Further, an inner diameter of the vertical section of the intermediate cashing is equal to or more than 220 mm, to ensure that three strings or pipes all can be installed in the intermediate cashing.
Further, an inner diameter of the integral joint tubing shall be at least more than 40 mm, and an inner diameter of the continuous tubing shall be at least less than 38 mm, so that the . õ
The present invention achieves steam injection, oil production and monitoring within the same shaft, so that steam injection, oil production and monitoring can be conducted within the same shaft at the same time, while the prior art only relates to steam injection and monitoring for huff and puff exploitation, and it is necessary to lift the steam injection and monitoring string out after the steam injection ends, and to place down a production string to conduct the oil production.
Further, as shown in FIG. 2, the oil production process equipment having three pipes within the same shaft also comprises an oil pumping pump 104 connected at a bottom end of the mechanical lifting string 103, for pumping steam condensed water in the horizontal well and crude oil doped in the steam condensed water. A piston of the oil pumping pump is connected with a sucker rod by a sucker rod releasing-connecting device. The depth L for which the oil pumping pump is placed down satisfies:
L>H-100(P-1) wherein, H is vertical depth of the reservoir, and P is stratum pressure.
Further, as shown in FIG. 2, the oil production process equipment having three pipes within the same shaft also comprises a horizontal well screen pipe hanger 106 disposed in the intermediate cashing, for hanging a screen pipe of the horizontal section of the horizontal well; a tail end screen 105 is located at a tail end of the screen pipe, for injecting steam into the horizontal section of the intermediate cashing.
Further, as shown in FIG 5, the sum of maximum outer diameters of the steam injection string, the mechanical lifting string, and the integral joint tubing is at least 10 mm less than an inner diameter of the vertical section of the intermediate cashing, to ensure that three strings or pipes all can be installed in the intermediate cashing. Further, an inner diameter of the vertical section of the intermediate cashing is equal to or more than 220 mm, to ensure that three strings or pipes all can be installed in the intermediate cashing.
Further, an inner diameter of the integral joint tubing shall be at least more than 40 mm, and an inner diameter of the continuous tubing shall be at least less than 38 mm, so that the . õ
13 , integral joint tubing can accommodate the continuous tubing.
Further, the inner diameter of a vertical section of the intermediate cashing is equal to or more than 220 mm, and a maximum outer diameter of the mechanical lifting string is equal to or more than 70mm, so that a size of the outer diameter of the mechanical lifting string can be increased, and space for the other two strings or pipes can be increased;
further, the maximum outer diameters of the oil pumping pump body and the oil pumping pump coupling are both equal to or less than 92 mm, so as to obtain reasonable space distribution.
The inner diameter of the mechanical lifting string is equal to or more than 62 mm, to ensure the lifting efficiency. Further, the inner diameter of the steam injection string is equal to or more than 40mm to ensure the steam injection quality.
Further, a sum of the outer diameter of a coupling of the steam injection string and the maximum outer diameter of the integral joint tubing is at least 10 mm less than an inner diameter of the horizontal section of the intermediate cashing, such that the steam injection string can be disposed in the horizontal section of the intermediate cashing.
As a preferable selection, the inner diameter of the steam injection string 102 is equal to or more than 40 mm, and the outer diameter thereof is equal to or less than 89 mm; the outer diameter of the coupling of the steam injection string 102 is at least 1 Omm less than the inner diameter of the horizontal section of the intermediate cashing, and preferably, the outer diameter of the coupling of the steam injection string is equal to or more than 108 mm, and the coupling adopts a bidirectional chamfer for connection.
Preferably, the outer diameter of the mechanical lifting string 103 is equal to or more than 70 mm, and an inner diameter thereof is equal to or more than 62 mm; the sum of the maximum outer diameter of the steam injection string 102 and the maximum outer diameter of the mechanical lifting string 103 is at least 10 mm less than the inner diameter of the vertical section of the intermediate cashing 101, and the coupling of the mechanical lifting string 103 is about 89 mm.
Further, through forced circulation by mechanical lifting, the steam is not simulated to enter the reservoir, heat is transferred mainly in the manner of heat conduction, and the stratum is heated depending only on the manner of heat conduction caused by temperature difference between the temperature of the steam and that of the stratum (or oil reservoir); the produced liquid is the condensed water formed after the injected steam is cooled, with the production-injection ratio being maintained at 1Ø
Further, the step A specifically comprises a step A2 of selecting a qualified reservoir, geological parameters of which satisfy the following conditions: the buried depth of the
Further, the inner diameter of a vertical section of the intermediate cashing is equal to or more than 220 mm, and a maximum outer diameter of the mechanical lifting string is equal to or more than 70mm, so that a size of the outer diameter of the mechanical lifting string can be increased, and space for the other two strings or pipes can be increased;
further, the maximum outer diameters of the oil pumping pump body and the oil pumping pump coupling are both equal to or less than 92 mm, so as to obtain reasonable space distribution.
The inner diameter of the mechanical lifting string is equal to or more than 62 mm, to ensure the lifting efficiency. Further, the inner diameter of the steam injection string is equal to or more than 40mm to ensure the steam injection quality.
Further, a sum of the outer diameter of a coupling of the steam injection string and the maximum outer diameter of the integral joint tubing is at least 10 mm less than an inner diameter of the horizontal section of the intermediate cashing, such that the steam injection string can be disposed in the horizontal section of the intermediate cashing.
As a preferable selection, the inner diameter of the steam injection string 102 is equal to or more than 40 mm, and the outer diameter thereof is equal to or less than 89 mm; the outer diameter of the coupling of the steam injection string 102 is at least 1 Omm less than the inner diameter of the horizontal section of the intermediate cashing, and preferably, the outer diameter of the coupling of the steam injection string is equal to or more than 108 mm, and the coupling adopts a bidirectional chamfer for connection.
Preferably, the outer diameter of the mechanical lifting string 103 is equal to or more than 70 mm, and an inner diameter thereof is equal to or more than 62 mm; the sum of the maximum outer diameter of the steam injection string 102 and the maximum outer diameter of the mechanical lifting string 103 is at least 10 mm less than the inner diameter of the vertical section of the intermediate cashing 101, and the coupling of the mechanical lifting string 103 is about 89 mm.
Further, through forced circulation by mechanical lifting, the steam is not simulated to enter the reservoir, heat is transferred mainly in the manner of heat conduction, and the stratum is heated depending only on the manner of heat conduction caused by temperature difference between the temperature of the steam and that of the stratum (or oil reservoir); the produced liquid is the condensed water formed after the injected steam is cooled, with the production-injection ratio being maintained at 1Ø
Further, the step A specifically comprises a step A2 of selecting a qualified reservoir, geological parameters of which satisfy the following conditions: the buried depth of the
14 reservoir is 680m, degassed oil viscosity under 50 C is 147500-485400 mPa.s, and thickness of the continuous reservoir is equal to 80 m.
Several embodiments are described in more detail as follows:
Embodiment 1: a sandstone formation oil layer of a reservoir, namely, a sandstone formation reservoir, with the buried depth being 955 m, degassed oil viscosity under 50H
being 53450-72340 mPa.s, and the thickness of the reservoir being equal to 15 m; at the last stage of the steam huff and puff in a vertical well, in the reservoir area are arranged two pairs of horizontal well groups, including two horizontal steam injection wells, two horizontal production wells and one horizontal observation well, wherein the direction of the horizontal wells keeps substantially parallel with the construction line, and distance between upper and lower horizontal wells is 5 m. As for geological features of the reservoir and properties of crude oil, a cycle preheating testing on dual horizontal well pair is developed.
An average thickness of the reservoir is more than 15 m, and degree of porosity, permeability, and a ratio of vertical permeability to horizontal permeability being more than 0.3, are suitable for SAGD technical exploitation;
As for the undeveloped reservoir, well placing adopts dual horizontal well group, with distance between the upper and lower horizontal wells being 5 m;
A steam injection string, a lifting string, and a lifting equipment are placed down into each of the upper and lower horizontal well shafts, and meanwhile an optical fiber temperature measurement system is placed down into the upper horizontal well to monitor temperature change of the horizontal section;
Wet saturated steam is injected into the steam injection string, production is conducted by utilizing the lifting equipment, and forced steam is circulated, wherein a steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t, cycle preheating lasts for four months, and the production-injection ratio is 1.
The monitored data from the optical fiber temperature measurement in the upper horizontal well shows that, after injecting steam into the lower horizontal well, temperature of the horizontal section of the upper horizontal well rises gradually, a well section in thermal communication is 260 m, which occupies 58% of the overall horizontal section, and this shows that the two wells become communicated with each other gradually.
Embodiment 2: Guantao reservoir of an oil field is middle-deep layer super heavy oil reservoir, with the buried depth being 680 m, degassed oil viscosity under 50 C being 147500¨'485400 mPa.s, and thickness of the reservoir being equal to 80 m.
Prior to the * - CA 02931882 2016-05-27 . _ present invention, the reservoir adopts a combination manner of dual horizontal wells, and production course thereof is divided into a huff and puff stage and a huff-puff preheating stage; at the huff and puff stage, the lower horizontal well conducts huff and puff for four cycles; and after the upper horizontal well goes into operation, the well group conducts 5 huff-puff preheating for two cycle. Periodic oil production and a gas oil ratio are both decreased, and the degree of production is 18%.
As for geological features of the reservoir and properties of crude oil, the present invention implements a cycle preheating of the upper and lower horizontal wells.
(1) The average thickness of the reservoir is more than 15 m, and degree of porosity, 10 permeability, and a ratio of vertical permeability to horizontal permeability being more than 0.3, are suitable for SAGD technical exploitation;
(2) As for the developed reservoir, well placing adopts dual horizontal well group, with distance between upper and lower horizontal wells being 4 m;
(3) A stream injection string, a lifting string and a lifting equipment are placed down into
Several embodiments are described in more detail as follows:
Embodiment 1: a sandstone formation oil layer of a reservoir, namely, a sandstone formation reservoir, with the buried depth being 955 m, degassed oil viscosity under 50H
being 53450-72340 mPa.s, and the thickness of the reservoir being equal to 15 m; at the last stage of the steam huff and puff in a vertical well, in the reservoir area are arranged two pairs of horizontal well groups, including two horizontal steam injection wells, two horizontal production wells and one horizontal observation well, wherein the direction of the horizontal wells keeps substantially parallel with the construction line, and distance between upper and lower horizontal wells is 5 m. As for geological features of the reservoir and properties of crude oil, a cycle preheating testing on dual horizontal well pair is developed.
An average thickness of the reservoir is more than 15 m, and degree of porosity, permeability, and a ratio of vertical permeability to horizontal permeability being more than 0.3, are suitable for SAGD technical exploitation;
As for the undeveloped reservoir, well placing adopts dual horizontal well group, with distance between the upper and lower horizontal wells being 5 m;
A steam injection string, a lifting string, and a lifting equipment are placed down into each of the upper and lower horizontal well shafts, and meanwhile an optical fiber temperature measurement system is placed down into the upper horizontal well to monitor temperature change of the horizontal section;
Wet saturated steam is injected into the steam injection string, production is conducted by utilizing the lifting equipment, and forced steam is circulated, wherein a steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t, cycle preheating lasts for four months, and the production-injection ratio is 1.
The monitored data from the optical fiber temperature measurement in the upper horizontal well shows that, after injecting steam into the lower horizontal well, temperature of the horizontal section of the upper horizontal well rises gradually, a well section in thermal communication is 260 m, which occupies 58% of the overall horizontal section, and this shows that the two wells become communicated with each other gradually.
Embodiment 2: Guantao reservoir of an oil field is middle-deep layer super heavy oil reservoir, with the buried depth being 680 m, degassed oil viscosity under 50 C being 147500¨'485400 mPa.s, and thickness of the reservoir being equal to 80 m.
Prior to the * - CA 02931882 2016-05-27 . _ present invention, the reservoir adopts a combination manner of dual horizontal wells, and production course thereof is divided into a huff and puff stage and a huff-puff preheating stage; at the huff and puff stage, the lower horizontal well conducts huff and puff for four cycles; and after the upper horizontal well goes into operation, the well group conducts 5 huff-puff preheating for two cycle. Periodic oil production and a gas oil ratio are both decreased, and the degree of production is 18%.
As for geological features of the reservoir and properties of crude oil, the present invention implements a cycle preheating of the upper and lower horizontal wells.
(1) The average thickness of the reservoir is more than 15 m, and degree of porosity, 10 permeability, and a ratio of vertical permeability to horizontal permeability being more than 0.3, are suitable for SAGD technical exploitation;
(2) As for the developed reservoir, well placing adopts dual horizontal well group, with distance between upper and lower horizontal wells being 4 m;
(3) A stream injection string, a lifting string and a lifting equipment are placed down into
15 shafts of each of the upper and lower horizontal wells;
(4) Wet saturated steam is injected into the steam injection string, production is conducted by utilizing the lifting equipment, and forced steam is circulated, wherein a working steam injection rate is 110 t/d, wellhead dryness is 95%, single-well steam injection is 10000 t, cycle preheating lasts for four months, and the production-injection ratio is 1.
In the well group, 2/3 of the horizontal section that was not employed uniformed is employed uniformly by cycle preheating under constant temperature difference, so that temperature of all horizontal sections reaches 150 C. In addition, a better effect is achieved after transferring to SAGD development. The upper horizontal well transfers into injection with steam injection amount of 180 t/d, the lower horizontal well adopts a 0120 mm pump for opening and production, wherein a fluid production of the well group is 184 t/d, an oil production is 40.3 t/d containing 78.2% of water, an instantaneous gas-oil ratio is 0.19, and an instantaneous production-injection ratio is 0.87. At the SAGD stage, steam injection amount is 43164 tons, a stage liquid production amount is 48858 tons, a stage oil production amount is 7042 tons, a stage gas-oil ratio is 0.16, a stage production-injection ratio is 1.13, an average daily oil production amount is 32.8 t/d, which exceeds an average daily oil production amount of the previous huff-puff preheating.
The present invention can solve the problems of uneven employment and difficult preheating start of horizontal wells of the middle-deep layer super heavy oil reservoir due to reservoir heterogeneity, and plays an important role of improving utilization efficiency of the
(4) Wet saturated steam is injected into the steam injection string, production is conducted by utilizing the lifting equipment, and forced steam is circulated, wherein a working steam injection rate is 110 t/d, wellhead dryness is 95%, single-well steam injection is 10000 t, cycle preheating lasts for four months, and the production-injection ratio is 1.
In the well group, 2/3 of the horizontal section that was not employed uniformed is employed uniformly by cycle preheating under constant temperature difference, so that temperature of all horizontal sections reaches 150 C. In addition, a better effect is achieved after transferring to SAGD development. The upper horizontal well transfers into injection with steam injection amount of 180 t/d, the lower horizontal well adopts a 0120 mm pump for opening and production, wherein a fluid production of the well group is 184 t/d, an oil production is 40.3 t/d containing 78.2% of water, an instantaneous gas-oil ratio is 0.19, and an instantaneous production-injection ratio is 0.87. At the SAGD stage, steam injection amount is 43164 tons, a stage liquid production amount is 48858 tons, a stage oil production amount is 7042 tons, a stage gas-oil ratio is 0.16, a stage production-injection ratio is 1.13, an average daily oil production amount is 32.8 t/d, which exceeds an average daily oil production amount of the previous huff-puff preheating.
The present invention can solve the problems of uneven employment and difficult preheating start of horizontal wells of the middle-deep layer super heavy oil reservoir due to reservoir heterogeneity, and plays an important role of improving utilization efficiency of the
16 horizontal sections at an initial stage of SAGD and accelerating oil production rate of SAGD.
The above description is merely illustrative of specific embodiments of the present invention, but not intended for limiting the scope of the present invention.
In order that components of the present invention can be combined one another on the condition that they are not conflicted, equivalent changes and modifications made by persons skilled in the art without departing from structure and principle of the present invention should all pertain to the protection scope of the invention.
The above description is merely illustrative of specific embodiments of the present invention, but not intended for limiting the scope of the present invention.
In order that components of the present invention can be combined one another on the condition that they are not conflicted, equivalent changes and modifications made by persons skilled in the art without departing from structure and principle of the present invention should all pertain to the protection scope of the invention.
Claims (10)
1. A method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference, characterized in that, the method comprises of:
a step A: selecting a qualified reservoir, geological parameters of which satisfy the following conditions: a buried depth of the reservoir is 600-1000 m, the thickness of the continuous reservoir is more than or equal to 10 m, and a ratio of a vertical permeability to a horizontal permeability is greater than 0.3;
a step B: providing dual horizontal wells in the qualified reservoir, while the dual horizontal wells comprises an upper horizontal well and a lower horizontal well with a distance of 4-6 m therebetween, wherein a well depth of the dual horizontal wells is less than 1600 m, and the length of horizontal sections of the dual horizontal wells is more than or equal to 300 m;
a step C: conducting steam huff and puff exploitation in the upper horizontal well and the lower horizontal well at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa;
a step D: then, placing an upper horizontal well steam injection string and an upper horizontal well mechanical lifting string down into the upper horizontal well of the dual horizontal wells, such that the upper horizontal well steam injection string extends to a position at 2/3 of the horizontal section of the upper horizontal well, and placing a lower horizontal well steam injection string and a lower horizontal well mechanical lifting string down into the lower horizontal well of the dual horizontal wells, such that the lower horizontal well steam injection string extends to a tiptoe of the horizontal section of the lower horizontal well; and a step E: then conducting cycle preheating, wherein continuous injection and production is performed in the upper horizontal well and the lower horizontal well perform at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile condensed liquid is extracted by the mechanical lifting, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and the condensed liquid in the lower horizontal well being extracted by the lower horizontal well.
a step A: selecting a qualified reservoir, geological parameters of which satisfy the following conditions: a buried depth of the reservoir is 600-1000 m, the thickness of the continuous reservoir is more than or equal to 10 m, and a ratio of a vertical permeability to a horizontal permeability is greater than 0.3;
a step B: providing dual horizontal wells in the qualified reservoir, while the dual horizontal wells comprises an upper horizontal well and a lower horizontal well with a distance of 4-6 m therebetween, wherein a well depth of the dual horizontal wells is less than 1600 m, and the length of horizontal sections of the dual horizontal wells is more than or equal to 300 m;
a step C: conducting steam huff and puff exploitation in the upper horizontal well and the lower horizontal well at the same time, such that the qualified reservoir is depressurized to below 3.5 MPa;
a step D: then, placing an upper horizontal well steam injection string and an upper horizontal well mechanical lifting string down into the upper horizontal well of the dual horizontal wells, such that the upper horizontal well steam injection string extends to a position at 2/3 of the horizontal section of the upper horizontal well, and placing a lower horizontal well steam injection string and a lower horizontal well mechanical lifting string down into the lower horizontal well of the dual horizontal wells, such that the lower horizontal well steam injection string extends to a tiptoe of the horizontal section of the lower horizontal well; and a step E: then conducting cycle preheating, wherein continuous injection and production is performed in the upper horizontal well and the lower horizontal well perform at the same time, wherein the steam is injected into the upper horizontal well and the lower horizontal well at the same time, and meanwhile condensed liquid is extracted by the mechanical lifting, the condensed liquid in the upper horizontal well being extracted by the upper horizontal well, and the condensed liquid in the lower horizontal well being extracted by the lower horizontal well.
2. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 1, characterized in that, the method further comprising a step F : after the cycle preheating lasts for two to four months, transferring to Steam Assisted Gravity Drainage development, in which the steam is injected by a steam injection well, and a production well is depressurized for production, wherein the upper horizontal well is the steam injection well and the lower horizontal well is the production well.
3. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 1, characterized in that, in the step C, the steam huff and puff exploitation is performed in the upper horizontal well and the lower horizontal well at the same time, so that the reservoir is depressurized to 3 to 3.5 MPa.
4. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 1, characterized in that, super heavy oil in a reservoir block of the qualified reservoir has fluid characteristics as follows: degassed oil viscosity under reservoir temperature is more than 50000 mPa.cndot.s, and relative density is more than 0.98 g/cm3.
5. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 2, characterized in that, the step F specifically comprises: transferring to the Steam Assisted Gravity Drainage development, when temperature between the steam injection well and the production well is higher than 90°C, and temperature of more than 80% of the horizontal sections of the steam injection well and the production well reaches 150°C.
6. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 2, characterized in that, the step A specifically comprises a step Al of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: the buried depth of the reservoir is 995 m, degassed oil viscosity under 50°C is 53450~72340 mPa.s, and the thickness of the continuous reservoir is equal to 15 m;
the step B specifically comprises a step B1 of providing, in the qualified reservoir, two pairs of dual horizontal wells, each pair including an upper horizontal well and a lower horizontal well with a distance of 5 m therebetween;
the step E specifically comprises a step E1 in which a working steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t;
and the step F specifically comprises a step F1 of conducting the cycle preheating for four months, a production-injection ratio being between 0.8 to 1.2.
the step B specifically comprises a step B1 of providing, in the qualified reservoir, two pairs of dual horizontal wells, each pair including an upper horizontal well and a lower horizontal well with a distance of 5 m therebetween;
the step E specifically comprises a step E1 in which a working steam injection rate is 110 t/d, wellhead dryness is 95%, and single-well steam injection is 10000 t;
and the step F specifically comprises a step F1 of conducting the cycle preheating for four months, a production-injection ratio being between 0.8 to 1.2.
7. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 1, characterized in that, the step D also comprises a step D1 in which the upper horizontal well is used as a monitoring well and an optical fiber temperature measurement system is placed down into the upper horizontal well.
8. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 1, characterized in that, through forced circulation by the mechanical lifting, the steam is not simulated to enter the reservoir; heat is transferred mainly in the manner of heat conduction, and the stratum is heated depending only on the manner of heat conduction caused by temperature difference between the temperature of the steam and that of the stratum; the extracted liquid is the condensed water formed after the injected steam is cooled, with the production-injection ratio being maintained at 1Ø
9. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 1, characterized in that, the step A specifically comprises a step A2 of selecting the qualified reservoir, the geological parameters of which satisfy the following conditions: the buried depth of the reservoir is 680 m, degassed oil viscosity under 50°C is 147500~485400 mPa.s, and the thickness of the continuous reservoir is equal to 80 m.
10. The method for forced steam cycle preheating dual horizontal wells in a middle-deep layer reservoir under a constant temperature difference according to claim 1, characterized in that, the upper horizontal well mechanical lifting string is disposed at an angle building section of the upper horizontal well, and the lower horizontal well mechanical lifting string is disposed at an angle building section of the lower horizontal well.
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| PCT/CN2013/088023 WO2015077954A1 (en) | 2013-11-28 | 2013-11-28 | Method for isothermal differential forced steam cyclic pre-heating for twin horizontal wells of mid-depth layer of oil reservoir |
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| CN106368660A (en) * | 2015-07-20 | 2017-02-01 | 中国石油天然气股份有限公司 | Method for extracting petroleum |
| CN108049836B (en) * | 2017-12-28 | 2024-03-26 | 中国石油天然气集团公司 | Pressurized SAGD wellhead replacement device and replacement method thereof |
| CN108661588A (en) * | 2018-06-23 | 2018-10-16 | 中国石油集团渤海石油装备制造有限公司 | A kind of Multi-pipe crossing high temperature test wellhead assembly |
| CN111550222B (en) * | 2019-02-11 | 2022-07-05 | 中国石油天然气股份有限公司 | Method for exploiting natural gas hydrate by injecting steam |
| CN110029975A (en) * | 2019-03-21 | 2019-07-19 | 新疆中凌工程技术有限公司 | Mudstone foundation structure and construction method above the horizontal well group steam injection of SAGD are broken up using straight well |
| CN115217454A (en) * | 2022-05-30 | 2022-10-21 | 中国石油化工股份有限公司 | Exploitation method of shallow heavy oil reservoir near denudation surface |
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| CN201843600U (en) * | 2010-11-16 | 2011-05-25 | 中国石油天然气股份有限公司 | SAGD mechanical lifting circulating preheating equipment |
| CN102900415B (en) * | 2012-09-25 | 2014-12-24 | 中国石油天然气股份有限公司 | Deep and ultra-deep heavy oil reservoir double-horizontal well fire flooding oil drainage exploitation method |
| CN103174403B (en) * | 2013-03-08 | 2016-08-10 | 中国石油天然气股份有限公司 | Gravity and steam flooding combined mining method for thick-layer interlayer-containing common heavy oil reservoir |
| CN103615225B (en) * | 2013-11-28 | 2017-07-07 | 中国石油天然气股份有限公司 | Double-horizontal-well isothermal difference forced steam circulation preheating method for middle-deep layer oil reservoir |
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