WO2015077954A1 - 中深层油藏双水平井等温差强制蒸汽循环预热方法 - Google Patents

中深层油藏双水平井等温差强制蒸汽循环预热方法 Download PDF

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WO2015077954A1
WO2015077954A1 PCT/CN2013/088023 CN2013088023W WO2015077954A1 WO 2015077954 A1 WO2015077954 A1 WO 2015077954A1 CN 2013088023 W CN2013088023 W CN 2013088023W WO 2015077954 A1 WO2015077954 A1 WO 2015077954A1
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Prior art keywords
horizontal well
steam
well
wells
horizontal
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PCT/CN2013/088023
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English (en)
French (fr)
Inventor
杨立强
杨建平
梁建宇
王宏远
鄢旭
侯国儒
魏耀
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中国石油天然气股份有限公司
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Application filed by 中国石油天然气股份有限公司 filed Critical 中国石油天然气股份有限公司
Priority to CA2931882A priority Critical patent/CA2931882C/en
Priority to PCT/CN2013/088023 priority patent/WO2015077954A1/zh
Publication of WO2015077954A1 publication Critical patent/WO2015077954A1/zh

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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

Definitions

  • the invention relates to the field of petroleum injection and production, and particularly relates to a method for pre-heating forced steam circulation preheating of a double horizontal well in a medium and deep reservoir, that is, a double horizontal well SAGD (steam assisted gravity drainage) for realizing a medium and deep super heavy oil reservoir. Efficient, balanced warm-up start method. Background technique
  • SAGD Steam-assisted gravity drainage
  • the thermal communication between the production wells generally adopts two preheating methods, namely steam preheating and steam cycle preheating.
  • steam preheating is the simultaneous development of steam stimulation at the upper and lower horizontal wells.
  • the purpose is to reduce the formation pressure and establish thermal communication.
  • the preheating stage of the throughput can finally reach the connection temperature between the horizontal wells to 80 °C, and the pressure drops to about 3 MPa.
  • the degree of recovery can reach 21%.
  • steam preheating does not uniformly heat the horizontal section.
  • the temperature field is inherited and the degree of heterogeneity is more serious. Therefore, relying on high-pressure throughput to achieve thermal connectivity often results in Uneven heating in the horizontal section will restrict the production of SAGD after development and reduce the ultimate recovery.
  • Circulating preheating means that the high temperature steam heats the oil layer without entering the oil layer (or a small amount entering the oil layer).
  • the steam circulates only once in the horizontal well, so it is called cycle preheating.
  • cycle preheating After a long enough (2-4 months) steam cycle in the injection-production well, thermal communication can be established between the injection-production wells, and the horizontal section can be uniformly heated.
  • self-circulation preheating of steam is only achieved in shallow heavy oil reservoirs. For medium and deep heavy oil reservoirs (600-1000 m), the pressure of steam is lower than that of shallow layers, for example, developed reservoirs.
  • the invention provides a method for pre-heating forced steam circulation preheating of a double horizontal well in a medium and deep reservoir to solve the problem of circulating preheating of a medium and deep heavy oil reservoir, and mainly solves the problem that the cyclic preheating of the middle and deep heavy oil reservoir is difficult to achieve. problem.
  • the present invention provides a method for pre-heating forced steam cycle preheating of a double horizontal well in a medium and deep reservoir, and the method for forcing a steam cycle preheating of a double horizontal well in a medium and deep reservoir includes:
  • Step A Select a qualified reservoir, the geological parameters of the qualified reservoir meet the following conditions:
  • the reservoir depth is
  • the thickness of the continuous oil layer is greater than or equal to 10m, and the ratio of the vertical permeability to the horizontal permeability is greater than 0.3;
  • Step B providing a double horizontal well in the qualified reservoir, the double horizontal well comprises: an upper horizontal well and a lower horizontal well with a well spacing of 4-6 m, and a well depth of the double horizontal well is less than 1600 m, a horizontal horizontal section of the double horizontal
  • the grading of the above-mentioned wells is reduced to 3. 5MPa or less;
  • Step D Then, in the upper horizontal well of the double horizontal well, the upper horizontal steam injection pipe column and the upper horizontal well mechanical lift pipe column are inserted, and the upper horizontal steam injection pipe column is deep to the upper horizontal well horizontal section. 2/3, in the lower horizontal well of the double horizontal well, the lower horizontal steam injection pipe column and the lower horizontal well mechanical lift pipe column are lowered, and the lower horizontal steam injection pipe column is deep to the toe of the horizontal section of the horizontal well;
  • Step E Then, the preheating is cycled, and the horizontal well and the lower horizontal well are simultaneously subjected to continuous injection and production, and steam is simultaneously injected into the upper horizontal well and the lower horizontal well, and the condensate is extracted by the mechanical lift, and the condensate in the horizontal well is used. It is produced by the upper horizontal well, and the condensate of the lower horizontal well is produced by the lower horizontal well.
  • the method for forcing steam cycle preheating of the double horizontal well in the medium and deep reservoir further comprises: Step F: After 2-4 months of circulating preheating, the steam is converted into steam assisted gravity drainage development, and the steam injection well is injected. The production well is depressurized, wherein the upper horizontal well is the steam injection well and the lower horizontal well is the production well.
  • step C the upper horizontal well and the lower horizontal well are simultaneously subjected to steam stimulation development to depressurize the reservoir to 3 to 3.5 MPa.
  • the characteristics of the super heavy oil in the reservoir block of the qualified reservoir are: the viscosity of the degassed crude oil at the oil layer temperature is greater than 50000 mPa*s, and the relative density is greater than 0.98 g/cm3.
  • the step F specifically includes: when the temperature between the steam well to be injected and the production well is greater than 90 ° C, and the temperature of the horizontal section of the steam injection well and the horizontal section of the production well reaches 150 ° C, the transfer is performed. Steam-assisted gravity drainage development, or continuous steam injection in steam injection wells, continuous production of horizontal wells.
  • the step A is specifically step A1: selecting a qualified reservoir, the geological parameter of the qualified reservoir satisfies the following conditions: the buried depth of the reservoir is 995 m, and the viscosity of the degassed crude oil at 50 ° C is 53450 to 72340 mPa. , the thickness of the continuous oil layer is equal to 15m;
  • the step B is specifically the step B1: two pairs of bi-level wells are disposed in the qualified reservoir, and each pair of the bi-level wells comprises: an upper horizontal well and a lower horizontal well having a well spacing of 5 m;
  • the step E is specifically the step E1: the working steam injection rate is 110t/d, the wellhead dryness is 95%, and the single well steam injection lOOOOt,
  • the step F is specifically step F1: the cycle is preheated for 4 months, and the ratio of the injection is between 0.8 and 1.2.
  • the step D further includes the step D1: the upper horizontal well is used as a monitoring well, and the optical fiber temperature measuring system is put into the upper horizontal well.
  • the mechanical circulation is forced to circulate, the steam is not excited to enter the oil layer, and the heat transfer mode is mainly heat conduction, and the formation is heated only by the heat conduction heat transfer method caused by the temperature difference between the steam and the formation temperature; the production liquid is cooled by the injected steam.
  • the condensed water is formed at a ratio of 1. 0.
  • step A is specifically step A2: selecting a qualified reservoir, the geological parameter of the qualified reservoir satisfies the following conditions: the reservoir is buried at a depth of 680 meters, and the viscosity of the degassed crude oil at 50 ° C is 147500 ⁇ 485400 mPa.
  • the continuous oil layer has a thickness of 80 meters.
  • the upper horizontal well mechanical lifting pipe string is disposed in the inclined section of the upper horizontal well, and the lower horizontal well mechanical lifting pipe string is disposed in the inclined section of the lower horizontal well.
  • the present invention inserts a mechanical lifting pipe column in the double horizontal well before the cycle preheating, in order to pass the mechanical lifting pipe column during the cycle preheating process.
  • the mechanical lift raises the high-temperature hot water back to the mining, and forces the steam circulation to achieve uniform heating of the oil layer.
  • FIG. 1 is a schematic view showing the working principle of an isothermal differential forced steam cycle preheating method for a double horizontal well in a medium and deep reservoir according to an embodiment of the present invention
  • FIG. 2 is a schematic structural view showing a main view direction of a horizontal well steam injection, oil recovery, and temperature and pressure real-time monitoring of a three-tube same well tubular oil production process device according to an embodiment of the present invention
  • FIG. 3 is a cross-sectional structural view showing a main well direction of a wellhead valve system of a horizontal well steam injection, oil recovery, and temperature and pressure real-time monitoring of a three-tube same well tubular production process apparatus according to an embodiment of the present invention
  • FIG. 4 is a schematic cross-sectional structural view of a horizontal well steam injection, oil recovery, and temperature and pressure real-time monitoring of a three-tube same wellbore production process equipment in a vertical section of a technical casing according to an embodiment of the present invention
  • Figure 5 is a horizontal well injection, oil recovery, and temperature in a horizontal section of a technical casing of an embodiment of the present invention. Pressure vertical monitoring of the vertical cross-sectional structure of the three-tube same well production process equipment;
  • FIG. 6 is a cross-sectional structural view (side view direction) of a jointless valve hanger of a wellhead valve system of a horizontal well steam injection, oil recovery, and temperature and pressure real-time monitoring of a three-tube same well tubular production process apparatus according to an embodiment of the present invention.
  • the present invention provides a method for pre-heating forced steam cycle preheating of a double horizontal well in a medium and deep reservoir, and the method for forcing a steam cycle preheating of a double horizontal well in a medium and deep reservoir includes:
  • Step A Select qualified reservoirs, confirm the feasibility of implementing the invention according to the known reservoir geological parameters and super heavy oil fluid characteristics; the geological parameters of the qualified reservoir of the present invention satisfy the following conditions:
  • the reservoir depth is 600-1000 m
  • the thickness of the continuous oil layer is greater than or equal to 10 m
  • the ratio of vertical permeability to horizontal permeability is greater than 0.3.
  • the present invention is directed to a medium-deep reservoir with a depth of 600-1000 m in the reservoir, and a shallow reservoir. Heat does not require the process of the present invention, too deep reservoirs require more complex processes and equipment;
  • Step B providing a double horizontal well in the qualified reservoir, the double horizontal well comprising: an upper horizontal well 1 and a lower horizontal well 3 having a well spacing of 4-6 m, and a well depth of the double horizontal well less than 1600 m, the double horizontal well
  • the length of each horizontal section is more than 300m, and the setting of the double horizontal wells and the parameters of the double horizontal wells provide guarantee for the subsequent cycle preheating;
  • Step C Simultaneously perform steam stimulation development on the upper level 1 well and the lower horizontal well 3, and depressurize the qualified reservoir to 3. 5 MPa or less, and prepare pressure and temperature conditions for subsequent cycle preheating, for example, by running in.
  • the steam pipe developed for steam stimulation is developed for steam stimulation. After the qualified oil pressure is reduced to 3.5 MPa or less, it will be used for steam stimulation. The developed pipe string is lifted out;
  • Step D After the qualified reservoir is depressurized to 3. 5 MPa or less, the upper horizontal well injection pipe column 17 and the upper horizontal well mechanical lift pipe column 15 are lowered into the upper horizontal well 1 of the double horizontal well, and the water is discharged.
  • the horizontal well injection pipe column 17 is deep to 2/3 of the horizontal section 10 of the upper horizontal well, that is, the end of the horizontal section 10 of the upper horizontal well is 1/3 of the length of the horizontal section 10 of the upper horizontal well, in the double horizontal well
  • the lower horizontal well 3 is lowered into the lower horizontal steam injection pipe column 37 and the lower horizontal well mechanical lifting pipe column 35, the lower horizontal well steam injection pipe column 37 is deep to the toe of the horizontal horizontal section 30; the upper horizontal well mechanical lifting pipe
  • the column 15 is disposed at the inclined section 13 or the heel of the upper horizontal well, and the lower horizontal well mechanical lifting column 35 is disposed at the inclined section 33 or the heel of the lower horizontal well;
  • Step E Then, the cycle preheating is performed, and the horizontal well and the lower horizontal well are simultaneously subjected to continuous injection and production, and the steam is simultaneously injected in the upper horizontal well and the lower horizontal well, and the condensed liquid is recovered by mechanical lifting, and the high temperature steam is from the wellhead to After the well, it is condensed into condensate.
  • the condensate in the horizontal well is produced by the upper horizontal well.
  • the condensate from the lower horizontal well is produced by the lower horizontal well.
  • the steam is returned in the well to form a complete cycle, reaching the middle and deep reservoir.
  • the purpose of cycle preheating is performed, and the horizontal well and the lower horizontal well are simultaneously subjected to continuous injection and production, and the steam is simultaneously injected in the upper horizontal well and the lower horizontal well, and the condensed liquid is recovered by mechanical lifting, and the high temperature steam is from the wellhead to After the well, it is condensed into condensate.
  • the condensate in the horizontal well is produced by the
  • the method for forcing steam cycle preheating of the double horizontal wells in the middle and deep reservoirs further comprises: Step F: After 2-4 months of circulating preheating, the steam is converted into steam assisted gravity drainage development, and the steam injection well is injected Production wells are produced by pressure reduction.
  • the upper horizontal well is the steam injection well
  • the lower horizontal well is the production well
  • the oil layer fluid enters the production well
  • the mechanical lift is used for continuous production to realize the gravity drainage development.
  • step C the upper horizontal well and the lower horizontal well are simultaneously subjected to steam stimulation development to depressurize the reservoir to 3 to 3.5 MPa. Because the pressure drop is too low, it is not conducive to the rise of high temperature water or condensate.
  • the characteristics of the super heavy oil in the reservoir block of the qualified reservoir are: the viscosity of the degassed crude oil at the oil layer temperature is greater than 50000 mPa*s, and the relative density is greater than 0.98 g/cm3. These parameters are suitable for the lift and warm-up process of the present invention.
  • the step F specifically includes: when the temperature of the oil layer between the steam well to be injected and the production well is greater than 90 ° C, and the temperature of the horizontal section of the steam injection well and the horizontal section of the production well reaches 150 ° C, The oil layer between the injection-production wells has been fully preheated and reached the thermal connection condition, and then transferred to the steam-assisted gravity drainage development, that is, the steam injection well is continuously injected. Horizontal wells are continuously produced.
  • step A is specifically step A1: selecting a qualified reservoir, the geological parameter of the qualified reservoir satisfies the following conditions: the buried depth of the reservoir is 995 m, and the viscosity of the degassed crude oil at 50 ° C is 53450 to 72340 mPa.
  • the continuous oil layer thickness is equal to 15m;
  • the step B is specifically the step B1: two pairs of bi-level wells are disposed in the qualified reservoir, and each pair of the bi-level wells comprises: an upper horizontal well and a lower horizontal well having a well spacing of 5 m, so that Increase efficiency and output;
  • the step E is specifically the step E1: the working steam injection rate is 110t/d, the wellhead dryness is 95%, and the single well steam injection is 10000t. These parameters are beneficial to the oil layer between the injection and production wells being fully preheated and achieving thermal communication. condition.
  • the step F is specifically the step F1: the cycle is preheated for 4 months, and the full preheating can be achieved, and the ratio of the injection is between 0.8 and 1.2, to achieve continuous circulation. 1, the cycle is ideal.
  • the step D further includes the step D1: the upper horizontal well is used as a monitoring well, and the optical horizontal temperature measuring system is used for detecting the downhole temperature in the upper horizontal well, and the monitoring data is displayed by the upper horizontal well optical fiber temperature monitoring data.
  • the temperature in the horizontal section gradually increases, and the thermal communication section is longer, indicating that the two wells are gradually connecting.
  • the present invention adopts the horizontal well steam injection, oil recovery, and temperature pressure of the following embodiment to monitor the three-tube same well production process equipment in real time, so as to simultaneously inject the steam column 102, machinery.
  • the lifting pipe column 103 and the coiled tubing are provided with a fiber optic temperature measuring system, for example, including a capillary tube and a plurality of thermocouples, to realize an organic combination of steam injection, lifting, and temperature measurement in the same wellbore, in the same In the wellbore, the above three functions can be realized.
  • a fiber optic temperature measuring system for example, including a capillary tube and a plurality of thermocouples
  • the three-tube same wellbore production process equipment includes: a wellhead valve system, a steam injection pipe string 102, a mechanical lift pipe column 103, and a couplingless oil pipe 109.
  • the technical casing 101 is disposed in a wellbore of a horizontal well, the technical casing comprising: a vertical section of the interconnected technical casing and a horizontal section of the technical casing; in a preferred embodiment, the technical casing 101
  • the inner diameter of the vertical section is 220 mm
  • the inner diameter of the horizontal section of the technical sleeve is 178.
  • the wellhead valve system as shown in Fig. 3, is disposed at the wellhead or the ground of the wellbore of the horizontal well, and is connected with the technical casing 101; the steam injection pipe column 102, the mechanical lifting pipe string 103, and the jointless oil pipe 109 are respectively disposed at Technical casing
  • the steam injection pipe column 102, the mechanical lift pipe column 103, and the jointless oil pipe 109 do not include each other, or the steam injection pipe column 102, the mechanical lift pipe column 103, and none.
  • the coupling oil pipe 109 has no socket relationship, and any one of the three pipe columns or pipes is disposed outside the other two;
  • the jointless oil pipe 109 includes: a vertical section of the jointless jointless oil pipe and a horizontal section of the jointless oil pipe; a vertical section of the jointless oil pipe is located in a vertical section of the technical casing, The horizontal section of the couplingless tubing is located In the horizontal section of the technical casing, the end of the jointless tubing string is located at the front of the steam outlet of the steam injection pipe, and is used for protecting the temperature and pressure monitoring coiled tubing;
  • the coiled tubing 110 is disposed in the jointless oil pipe 109.
  • the coiled tubing is provided with a capillary tube and a plurality of thermocouples, and the coiled tubing comprises: interconnected coiled tubing a vertical section and a horizontal section of the coiled tubing, wherein a vertical section of the coiled tubing is located in a vertical section of the jointless tubing, and a horizontal section of the coiled tubing of the coiled tubing is located in a horizontal section of the jointless tubing
  • the end of the coiled tubing is substantially equivalent to the end of the jointless tubing, and is used for filling capillary pressure measurement and thermocouple temperature measurement; the capillary test pressure should be less than 15 MPa, and the plurality of thermocouple test temperatures should be less than 450 ° C,
  • the coiled tubing is filled with a heat-resistant protective material; the steam-injecting pipe string 102 includes: a vertical section 107
  • the steam injection pipe column includes from the outside to the inside: an insulated outer tube 305, a heat insulating layer 306, and a heat insulating inner tube 307, and the heat insulating layer 306 is sandwiched between Between the insulated outer tube 305 and the insulated inner tube 307; the mechanical lifting column 103 is disposed in a vertical section of the technical casing for lifting liquid (crude oil) in the wellbore;
  • the mechanical lift string 103 includes a pumping pipe connected by a pumping pipe coupling 304;
  • the wellhead valve system includes: a thick flange seal body 209, a jointless tubing hanger 208, a pumping pipe outlet 201, and a steam inlet 202 (FIG. 3), and the steam inlet 202 is disposed on the thick flange sealing body. 209.
  • the jointless oil pipe 109 and the coiled tubing 110 are suspended on the jointless oil pipe hanger 208, and the mechanical lift pipe column 103 is connected to the oil suction pipe outlet 201, and the steam injection pipe column 102 is connected to the Steam inlet 202.
  • the jointless tubing hanger 208 is disposed on the thick flange seal body 209.
  • the jointless tubing hanger 208 has a signal receiving system for converting the signals received in the coiled tubing 110 into temperature and pressure data.
  • the wellhead valve system further includes: a casing annulus 203, a polished rod 204, a polished rod sealer 205, a rubber gate 206, and a remote hydraulic sealer 207.
  • the present invention is significantly different from the existing wellhead equipment at the wellhead.
  • the present invention is provided at the wellhead, that is, at the wellhead valve system, there are components for connecting or suspending three pipe columns or pipes, and the mechanical lifting pipe column is connected to the oil pipe outlet 201, and the steam pipe column is injected. 102 connects the steam inlet 202, and the jointless oil pipe 109 and the coiled tubing 110 are suspended from the jointless oil pipe hanger 208.
  • both the steam injection pipe column and the mechanical lift pipe column are directly suspended on the thick flange sealing body 209, which is the original oil pipe hanger of the wellhead, which is the same as the prior art, but otherwise
  • the present invention also suspends the jointless tubing hanger 208 on the thick flange seal body 209 for securing and connecting the coiled tubing 110.
  • the present invention has a steam inlet 202 on the thick flange sealing body 209, and is also a couplingless tubing hanger 208.
  • the jointless tubing hanger 208 is disposed laterally of the steam inlet 202. As seen from Figure 3, the jointless tubing hanger 208 is disposed at the steam inlet. The rear of 202.
  • the invention realizes steam injection, oil recovery and monitoring in the same wellbore, so that steam injection, oil recovery and monitoring can be carried out simultaneously in the same wellbore, while the prior art only performs steam injection and monitoring for throughput development, and needs to be finished at the steam injection. After the steam injection and monitoring of the pipe string and the entry into the production pipe string, the oil production operation can be carried out.
  • the three-tube same wellbore production process equipment further includes: a pumping pump 104 connected to the lower bottom end of the mechanical lifting column 103 for extracting steam condensed water and steam condensation in the horizontal well Crude oil doped in water.
  • the piston of the oil pump is connected to the sucker rod by a sucker rod disconnector.
  • the pumping depth D is satisfied:
  • the three-tube same wellbore oil recovery process equipment further includes: a horizontal well screen hanger 106, disposed in the technical casing, in a horizontal section of the horizontal well, and an end screen 105. Located at the end of the screen for injecting steam into the horizontal section of the technical casing.
  • the sum of the maximum outer diameter of the steam injection pipe string, the mechanical lift pipe column and the maximum outer diameter of the jointless oil pipe is at least 10 mm smaller than the inner diameter of the vertical section of the technical casing to ensure three Each string or pipe can be installed in a technical casing.
  • the vertical portion of the technical sleeve has an inner diameter of 220 mm to ensure that all three columns or pipes can be installed in the technical casing.
  • the inner diameter of the jointless oil pipe should be at least 40 mm, and the inner diameter of the coiled oil pipe should be at least 38 mm so that the jointless oil pipe accommodates the coiled oil pipe.
  • the inner diameter of the vertical portion of the technical sleeve is 220 mm
  • the maximum outer diameter of the mechanical lifting column is 70, so that the outer diameter of the mechanical lifting column can be reduced, and the other two columns can be added.
  • the space of the pipeline further, the maximum outer diameter of the pump body and the oil pump coupling are both 92 mm to obtain a reasonable space allocation.
  • the mechanical lifting column has an inner diameter of 62 mm to ensure lifting efficiency.
  • the steam injection pipe has an inner diameter of 40 mm to ensure the steam injection quality.
  • the sum of the outer diameter of the coupling of the steam injection pipe string and the maximum outer diameter of the jointless oil pipe is at least 10 mm smaller than the inner diameter of the horizontal section of the technical casing, so that the steam injection pipe column can be disposed at In the horizontal section of the technical casing.
  • the outer diameter of the coupling of the pipe string is 108 mm, and the coupling is connected by a two-way chamfer.
  • the outer diameter 70 of the mechanical lift column 103 allows the inner diameter 62 to be; the sum of the maximum outer diameter of the steam injection string 102 and the maximum outer diameter of the mechanical lift tube 103 column.
  • the inner diameter of the vertical portion of the sleeve 101 is at least 10 mm smaller, and the coupling of the mechanical lift column 103 is approximately 89 mm.
  • the mechanical circulation is forced to circulate, the steam is not excited to enter the oil layer, and the heat transfer mode is mainly heat conduction, and the formation is heated only by the heat conduction heat transfer method caused by the temperature difference between the temperature of the steam and the formation (or the oil layer); the production liquid is injected 0 ⁇ The condensed water formed by the cooling, the injection ratio is maintained at 1.0.
  • step A is specifically step A2: selecting a qualified reservoir, the geological parameter of the qualified reservoir satisfies the following conditions: the reservoir is buried at a depth of 680 meters, and the viscosity of the degassed crude oil at 50 ° C is 147500 ⁇ 485400 mPa.
  • the continuous oil layer has a thickness of 80 meters.
  • Example 1 A sandstone group reservoir of a reservoir is a sandstone reservoir with a depth of 955 m.
  • the viscosity of degassed crude oil at 50 °C is 53450 ⁇ 72340 mPa ⁇ s, and the thickness of the reservoir is 15 m, at the end of vertical steam stimulation.
  • Two pairs of horizontal well groups are deployed in the reservoir area, including 2 horizontal steam injection wells, 2 horizontal production wells, and 1 horizontal observation well.
  • the horizontal well direction is basically parallel with the construction line, and the distance between the upper and lower horizontal wells is It is 5 meters. According to the geological characteristics of the reservoir and the nature of the crude oil, a cyclic preheating test of the double horizontal well pair was carried out.
  • the oil layer has an average thickness of more than 15 meters, and the porosity, permeability, vertical permeability and horizontal permeability ratio are greater than 0.3, which is suitable for SAGD technology mining;
  • the well pattern is a double horizontal well group, and the upper and lower horizontal wells are 5 meters apart;
  • the upper horizontal well fiber optic temperature monitoring data shows that after the horizontal well injection, the temperature of the horizontal section of the upper horizontal well gradually increases, and the thermal communication section is 260 m, accounting for 58% of the total horizontal section, indicating that the two wells are gradually connecting.
  • Example 2 The oil layer of Guantao Formation in an oilfield is a medium-deep super-heavy oil reservoir with a depth of 680 m.
  • the viscosity of degassed crude oil at 50 °C is 147500 ⁇ 485400mPa.s, and the thickness of the oil layer is 80m.
  • the reservoir adopts a dual horizontal well combination method, and its production process is divided into two stages of throughput and throughput preheating. In the throughput stage, the lower horizontal well is swallowed for four cycles, and after the upper horizontal well is put into operation, the well group is preheated by the throughput. Two cycles. The cycle oil production and oil-to-gas ratio are both decreasing, and the degree of recovery is 18%.
  • the present invention implements cyclic preheating of the upper and lower horizontal wells.
  • the average thickness of the oil layer is greater than 15 m, the porosity, permeability, vertical permeability and horizontal permeability ratio are greater than 0.3, suitable for SAGD technology mining;
  • the reservoir has been developed, and the well pattern is a combination of double horizontal wells, and the distance between the upper and lower horizontal wells is 4 meters;
  • the well group was uniformly warmed by the isothermal differential cycle preheating, and the 2/3 horizontal section that did not reach uniform utilization was uniformly used, and the temperature of all the horizontal sections reached 150 °C. And after transferring to SAGD development, it achieved good results.
  • the upper horizontal well is transferred, the daily injection steam is 180 tons, the lower horizontal well is produced by ⁇ 120 ⁇ pumping, the well group is 184 tons of daily production, the daily production is 40. 3 tons, the water content is 78.2%, the instantaneous oil-air ratio is 0. 19, instantaneous The sampling ratio is 0.87.
  • 43164 tons of steam were injected, 48858 tons of liquid produced in the stage, 7042 tons of oil produced in the stage, and the stage oil-gas ratio was 0.16.
  • the stage production ratio was 1.13.
  • the average daily oil production was 32. 8t/d, exceeding the average preheating of the previous throughput. Nissan oil quantity.
  • the invention can solve the problem that the horizontal well of the middle-deep super-heavy oil reservoir is caused by the heterogeneity of the reservoir and the difficulty of warming up, and the utilization efficiency of the horizontal section of the SAGD is improved and the oil production rate of the SAGD is accelerated. Important promotion.

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Abstract

一种中深层油藏双水平井等温差强制蒸汽循环预热方法，所述中深层油藏双水平井等温差强制蒸汽循环预热方法包括：步骤A：选择合格油藏；步骤B：在所述合格油藏中部署双水平井；步骤C：对上水平井和下水平井同时进行蒸汽吞吐开发，使所述合格油藏降压至3.5MPa以下；步骤D：在所述双水平井的上水平井中下入上水平井注汽管柱和上水平井机械举升管柱，在双水平井的下水平井中下入下水平井注汽管柱和下水平井机械举升管柱；步骤E：循环预热，上水平井和下水平井同时进行连续的注入采出，将蒸汽在上水平井和下水平井内同时注入，同时利用机械举升回采冷凝液，上水平井内的冷凝液由上水平井采出，下水平井的冷凝液由下水平井采出。

Description

中深层油藏双水平井等温差强制蒸汽循环预热方法
技术领域
本发明涉及石油注采领域， 具体涉及一种中深层油藏双水平井等温差强制蒸汽循环 预热方法， 即一种实现中深层超稠油油藏双水平井 SAGD (蒸汽辅助重力泄油）高效、均 衡预热启动方法。 背景技术
蒸汽辅助重力泄油 （SAGD )是开发稠油油藏的有效技术手段， 对于在地层原始条件 下没有流动能力的高粘度原油， 需经历油层预热阶段， 实现注采井之间的热连通， 充分 预热油层是实现重力泄油的前提。
为建立双水平井组合 SAGD注、 采井之间的热连通一般采取两种预热的方式， 即蒸 汽吞吐预热和蒸汽循环预热。
其中蒸汽吞吐预热是上下水平井同时进行蒸汽吞吐开发， 目的是降低地层压力， 建 立热连通， 吞吐预热阶段最终可使水平井井间连通温度达到 80 °C， 压力下降至 3MPa左 右， 阶段采出程度可达到 21%。 但是蒸汽吞吐预热不能均匀加热水平段， 随着吞吐轮次 的增加， 温场呈继承性发展， 非均质程度更加严重， 所以， 完全依靠高压吞吐生产来达 到取得热连通目的， 往往会造成水平段加热不均匀， 必将制约转入 SAGD开发后生产效 果， 降低最终采收率。 循环预热是指高温蒸汽在不进入油层 （或极少量进入油层） 的情况下加热油层， 蒸 汽仅在水平井内循环一圈，故称循环预热。从理论上讲在注采井中进行足够长时间（2-4 个月） 的蒸汽循环后， 注采井间能够建立热连通， 且水平段可得到均匀加热。 但是实际 应用中仅在浅层稠油油藏实现了蒸汽的自循环预热，对于中深层稠油油藏（600-1000m)， 由于蒸汽吞吐压力较浅层更低， 例如， 已开发油藏在蒸汽吞吐降压至 3-4MPa， 在中深层 稠油油藏， 高温热水难以实现自循环， 中深层稠油油藏的循环预热难以实现， 限制了中 深层稠油油藏的开采。 发明内容 本发明提供一种中深层油藏双水平井等温差强制蒸汽循环预热方法， 以针对中深层 稠油油藏的循环预热问题， 主要解决中深层稠油油藏的循环预热难以实现的问题。
为此， 本发明提出一种中深层油藏双水平井等温差强制蒸汽循环预热方法， 所述中 深层油藏双水平井等温差强制蒸汽循环预热方法包括：
步骤 A : 选择合格油藏， 所述合格油藏的地质参数满足以下条件： 油藏埋深为
600-1000m, 连续油层厚度大于等于 10m， 垂向渗透率与水平渗透率比例大于 0. 3 ;
步骤 B: 在所述合格油藏中设置双水平井， 所述双水平井包括： 井距为 4-6m的上水 平井和下水平井， 双水平井的井深小于 1600米， 双水平的水平段长度在 300m以上； 步骤 C: 对上水平井和下水平井同时进行蒸汽吞吐开发， 使所述合格油藏降压至 3. 5MPa 以下；
步骤 D: 然后， 在所述双水平井的上水平井中下入上水平井注汽管柱和上水平井机 械举升管柱， 上水平井注汽管柱下深到上水平井水平段的 2/3处， 在所述双水平井的下 水平井中下入下水平井注汽管柱和下水平井机械举升管柱， 下水平井注汽管柱下深到下 水平井水平段的脚尖处；
步骤 E: 然后循环预热， 上水平井和下水平井同时进行连续的注入采出， 将蒸汽在 上水平井和下水平井内同时注入， 同时利用机械举升回采冷凝液， 上水平井内的冷凝液 由上水平井采出， 下水平井的冷凝液由下水平井采出。
进一步地， 中深层油藏双水平井等温差强制蒸汽循环预热方法还包括： 步骤 F: 在 循环预热 2-4个月后， 转为蒸汽辅助重力泄油开发， 注汽井注汽， 生产井降压生产， 其 中， 上水平井为注汽井， 下水平井为生产井。
进一步地， 步骤 C中， 上水平井和下水平井同时进行蒸汽吞吐开发使油藏降压至 3 至 3· 5MPa。
进一步地， 所述合格油藏的油藏区块中的超稠油流体特性为： 油层温度下脱气原油 粘度大于 50000mPa* s， 相对密度大于 0. 98g/cm3。
进一步地， 步骤 F具体包括： 待注汽井和生产井之间的温度大于 90 °C， 注汽井的水 平段和生产井的水平段的 80%以上区域温度达到 150 °C时，转入蒸汽辅助重力泄油开发， 或者注汽井连续注汽， 水平井连续生产。
进一步地， 所述步骤 A具体为步骤 A1 : 选择合格油藏， 所述合格油藏的地质参数满 足以下条件： 油藏埋深为 995m， 50 °C下脱气原油粘度为 53450〜72340mPa. s， 连续油层 厚度等于 15m; 所述步骤 B具体为步骤 Bl :在所述合格油藏中设置两个成对的双水平井，每对所述 双水平井包括： 井距为 5m的上水平井和下水平井；
所述步骤 E具体为步骤 E1 : 工作注汽速率为 110t/d， 井口干度为 95%， 单井注汽 lOOOOt,
所述步骤 F具体为步骤 F1 : 循环预热 4个月， 采注比在 0. 8至 1. 2之间。
进一步地， 所述步骤 D还包括步骤 D1 : 所述上水平井做为监测井， 在所述上水平井 下入光纤测温***。
进一步地，通过机械举升强制循环，蒸汽不激励进入油层，传热方式以热传导为主， 仅靠蒸汽与地层温度的温差引起的热传导传热方式加热地层； 采出液为注入的蒸汽冷却 后形成的冷凝水， 采注比保持在 1. 0。
进一步地， 所述步骤 A具体为步骤 A2: 选择合格油藏， 所述合格油藏的地质参数满 足以下条件： 油藏埋深 680米， 50°C下脱气原油粘度为 147500〜485400mPa. s， 连续油 层厚度为 80米。
上水平井机械举升管柱设置在所述上水平井的造斜段， 下水平井机械举升管柱设置 在所述下水平井的造斜段。
相对于中深层油藏传统的循环预热方式，本发明在循环预热之前在双水平井中下入 了机械举升管柱， 以在循环预热的过程中， 能够通过机械举升管柱的机械举升将高温热 水举升回采， 强制蒸汽循环， 达到等油层的温差均匀加热， 这样， 就克服了传统的循环 预热方式在中深层油藏难以实现循环预热的缺点。
附图说明
图 1为根据本发明实施例的中深层油藏双水平井等温差强制蒸汽循环预热方法的工 作原理示意图；
图 2为本发明实施例的水平井注汽、 采油、 以及温度压力实时监测三管同井筒采油 工艺设备的主视方向的结构示意图；
图 3为本发明的实施例的水平井注汽、 采油、 以及温度压力实时监测三管同井筒采 油工艺设备的井口阀门***的主视方向的剖视结构示意图；
图 4为本发明的实施例的位于技术套管的垂直段中的水平井注汽、 采油、 以及温度 压力实时监测三管同井筒采油工艺设备的水平方向剖面结构示意图；
图 5为本发明的实施例的位于技术套管的水平段中的水平井注汽、 采油、 以及温度 压力实时监测三管同井筒采油工艺设备的垂直方向剖面结构示意图；
图 6为本发明的实施例的水平井注汽、 采油、 以及温度压力实时监测三管同井筒采 油工艺设备的井口阀门***的无接箍油管悬挂器的剖视结构示意图 （侧视方向）。
附图标号说明：
1、 上水平井 10、 水平段 13、 造斜段 15、 上水平井机械举升管 柱 17、 上水平井注汽管柱
3、 下水平井 30、 水平段 33、 造斜段 35、 下水平井机械举升管 柱 17、 下水平井注汽管柱
101技术套管 102注蒸汽管柱 103机械举升管柱、 104抽油泵、 105末端筛 106水 平井的筛管悬挂器 107注蒸汽管柱的垂直段 108注蒸汽管柱的水平段 109无接箍 油管 110连续油管 202蒸汽入口， 203套管环空出入口， 204光杆， 205光杆密封 器， 206 胶皮间门， 207 远程液压封井器， 208无接箍油管悬挂器 209厚法兰密封主 体 304抽油管接箍 305隔热管 306保温层 307隔热内管 具体实施方式
为了对本发明的技术特征、 目的和效果有更加清楚的理解， 现对照附图说明本发明 的具体实施方式。
如图 1所示， 本发明提出一种中深层油藏双水平井等温差强制蒸汽循环预热方法， 所述中深层油藏双水平井等温差强制蒸汽循环预热方法包括：
步骤 A: 选择合格油藏， 根据已知油藏地质参数及超稠油流体特性确认实施本发明 的可行性； 本发明的合格油藏的地质参数满足以下条件： 油藏埋深为 600-1000m为中深 层油藏， 连续油层厚度大于等于 10m， 垂向渗透率与水平渗透率比例大于 0. 3， 本发明 针对油藏埋深为 600-1000m的中深层油藏， 浅层油藏的预热无需本发明的工艺方法， 太 深油藏则需要更为复杂的工艺和设备；
步骤 B: 在所述合格油藏中设置双水平井， 所述双水平井包括： 井距为 4-6m的上水 平井 1和下水平井 3， 双水平井的井深小于 1600米， 双水平井的各水平段长度在 300m 以上， 双水平井的设置以及双水平井的各项参数为后序的循环预热提供了保证；
步骤 C: 对上水平 1井和下水平井 3同时进行蒸汽吞吐开发， 使所述合格油藏降压 至 3. 5MPa 以下， 为后续的循环预热准备压力和温度条件， 例如， 通过下入用于蒸汽吞 吐开发的管柱进行蒸汽吞吐开发， 合格油藏降压至 3. 5MPa 以下后， 再将用于蒸汽吞吐 开发的管柱提升出来；
步骤 D:合格油藏降压至 3. 5MPa以下后，在所述双水平井的上水平井 1中下入上水 平井注汽管柱 17和上水平井机械举升管柱 15，上水平井注汽管柱 17下深到上水平井水 平段 10的 2/3处， 即距离上水平井水平段 10的末端为上水平井水平段 10长度的 1/3， 在所述双水平井的下水平井 3中下入下水平井注汽管柱 37和下水平井机械举升管柱 35， 下水平井注汽管柱 37下深到下水平井水平段 30的脚尖处； 上水平井机械举升管柱 15 设置在所述上水平井的造斜段 13或脚跟处， 下水平井机械举升管柱 35设置在所述下水 平井的造斜段 33或脚跟处； 上述参数的设置， 考虑到实现水平井之间的热连通， 以及 上水平井的水平段整体的预热效果和下水平井的水平段整体的预热效果，保证各水平井 的冷凝液得以强制循环；
步骤 E: 然后进行循环预热， 上水平井和下水平井同时进行连续的注入采出， 将蒸 汽在上水平井和下水平井内同时注入， 同时利用机械举升回采冷凝液， 高温蒸汽从井口 到井下后， 冷凝成冷凝液， 上水平井内的冷凝液由上水平井采出， 下水平井的冷凝液由 下水平井采出， 蒸汽在井中又进有回， 形成完整循环， 达到了中深层油藏循环预热的目 的。
通过设置双水平井、 以及在双水平井中设置机械举升管柱， 并选择合适的各工艺参 数， 能够实现中深层油藏的双水平井的强制蒸汽循环， 实现等温差均匀加热， 使得双水 平井之间的油层已充分预热并达到热连通条件。
进一步地， 中深层油藏双水平井等温差强制蒸汽循环预热方法还包括： 步骤 F: 在 循环预热 2-4个月后， 转为蒸汽辅助重力泄油开发， 用注汽井注汽， 生产井降压生产， 其中， 上水平井为注汽井， 下水平井为生产井， 让油层流体进入到生产井中， 采用机械 举升连续生产， 实现重力泄油开发。
进一步地， 步骤 C中， 上水平井和下水平井同时进行蒸汽吞吐开发使油藏降压至 3 至 3. 5MPa。 因为， 压力降得太低也不利于高温水或冷凝液的举升。
进一步地， 所述合格油藏的油藏区块中的超稠油流体特性为： 油层温度下脱气原油 粘度大于 50000mPa* s , 相对密度大于 0. 98g/cm3。 这些参数适合本发明的举升和预热 过程。
进一步地， 步骤 F具体包括： 待注汽井和生产井之间的油层温度大于 90 °C， 注汽井 的水平段和生产井的水平段的 80%以上区域温度达到 150 °C时， 这样， 注采井之间的油 层已充分预热并达到热连通条件，然后转入蒸汽辅助重力泄油开发，即注汽井连续注汽， 水平井连续生产。
进一步地， 所述步骤 A具体为步骤 A1 : 选择合格油藏， 所述合格油藏的地质参数满 足以下条件： 油藏埋深为 995m， 50°C下脱气原油粘度为 53450〜72340mPa. s连续油层厚 度等于 15m;
所述步骤 B具体为步骤 B1 :在所述合格油藏中设置两个成对的双水平井，每对所述 双水平井包括： 井距为 5m的上水平井和下水平井， 这样， 可以增加效率和产量；
所述步骤 E具体为步骤 E1 : 工作注汽速率为 110t/d， 井口干度为 95%， 单井注汽 10000t, 这些参数有利于注采井之间的油层已充分预热并达到热连通条件。
所述步骤 F具体为步骤 F1 : 循环预热 4个月， 可以实现充分预热， 采注比在 0. 8 至 1. 2之间， 以实现连续循环， 作为较佳选择， 采注比为 1， 循环比较理想。
进一步地， 所述步骤 D还包括步骤 D1 : 所述上水平井做为监测井， 在所述上水平井 下入光纤测温***， 用于检测井下温度， 通过上水平井光纤测温监测资料显示， 下水平 井注汽后， 水平段温度逐渐升高， 热连通井段较长， 表明两口井之间正在逐步连通。 例如， 上水平井做为监测井时， 本发明采用下面一个实施例的水平井注汽、 采油、 以及温度压力实时监测三管同井筒采油工艺设备， 以同时下入注蒸汽管柱 102、 机械举 升管柱 103、 以及连续油管， 连续油管内设有光纤测温***， 例如包括毛细管及多组热 电偶， 以实现在同一井筒中， 注汽、 举升、 测温的有机组合， 在同一井筒中， 能够实现 上述三个功能。
如图 2， 所述三管同井筒采油工艺设备包括： 井口阀门***、 注蒸汽管柱 102、 机 械举升管柱 103、 以及无接箍油管 109。
技术套管 101， 设置在水平井的井筒中， 所述技术套管包括： 相互连接的技术套管 的垂直段及技术套管的水平段； 在一较佳实施中， 所述技术套管 101的垂直段的内径 220mm, 所述技术套管的水平段的内径 178讓。
井口阀门***，如图 3，设置在水平井的井筒的井口处或地面，并连接技术套管 101 ; 注蒸汽管柱 102、 机械举升管柱 103、 以及无接箍油管 109， 分别设置在技术套管
101中， 如图 4和图 5， 注蒸汽管柱 102、 机械举升管柱 103、 以及无接箍油管 109互不 包含， 或者说注蒸汽管柱 102、 机械举升管柱 103、 以及无接箍油管 109这三者没有套 接的关系， 这三个管柱或管道中的任一个均设置在其他两个之外；
所述无接箍油管 109包括:相互连接的无接箍油管的垂直段及无接箍油管的水平段; 所述无接箍油管的垂直段位于所述技术套管的垂直段中，所述无接箍油管的水平段位于 所述技术套管的水平段中， 所述无接箍油管柱的末端位于所述注蒸汽管柱的出汽口前 部， 用于保护温压监测连续油管；
如图 4和图 5， 所述连续油管 110， 设置在所述无接箍油管 109中， 所述连续油管 内设有毛细管及多组热电偶， 所述连续油管包括： 相互连接的连续油管的垂直段及连续 油管的水平段， 所述连续油管的垂直段位于所述无接箍油管的垂直段中， 所述连续油管 的垂直段水平段位于所述无接箍油管的水平段中，所述连续油管的末端与无接箍油管末 端基本相当， 用于充填毛细管测压及热电偶测温； 所述毛细管测试压力应小于 15MPa， 所述多组热电偶测试温度应小于 450°C， 与所述连续油管间采用耐热保护材料充填； 所述注蒸汽管柱 102包括： 相互连接的注蒸汽管柱的垂直段 107及注蒸汽管柱的水 平段 108， 所述注蒸汽管柱的垂直段位于所述技术套管的垂直段中， 所述注蒸汽管柱的 水平段位于所述技术套管的水平段中，所述注蒸汽管柱的末端向水平井井筒注入蒸汽实 现原油开发及油层预热； 如图 4和图 5所示， 注汽管柱从外向内包括： 隔热外管 305、 保温层 306以及隔热内管 307， 保温层 306夹设在隔热外管 305与隔热内管 307之间； 所述机械举升管柱 103设置在所述技术套管的垂直段中，用于举升井筒内的液体 (原 油）； 如图 5， 机械举升管柱 103包括通过抽油管接箍 304连接起来的抽油管；
如图 6， 所述井口阀门***包括： 厚法兰密封主体 209、无接箍油管悬挂器 208、抽 油管出口 201以及蒸汽入口 202 (如图 3)，蒸汽入口 202设置在厚法兰密封主体 209上。
所述无接箍油管 109及连续油管 110悬挂在所述无接箍油管悬挂器 208上，所述机 械举升管柱 103连接所述抽油管出口 201，所述注蒸汽管柱 102连接所述蒸汽入口 202。 如图 6， 无接箍油管悬挂器 208设置在厚法兰密封主体 209上， 无接箍油管悬挂器 208 中有信号接收***， 将连续油管 110中接收到的信号转换为温度和压力数据。 此外， 如 图 3， 所述井口阀门***还包括： 套管环空出入口 203， 光杆 204， 光杆密封器 205， 胶 皮闸门 206， 远程液压封井器 207。
本发明除了在井筒中同时设有三个管柱或管道外， 在井口处， 本发明与现有井口设 备有明显区别。 其中的一个主要区别为： 本发明在井口处， 即在井口阀门***同时设有 连接或悬挂三个管柱或管道的部件， 机械举升管柱连接所述抽油管出口 201， 注蒸汽管 柱 102连接所述蒸汽入口 202， 无接箍油管 109及连续油管 110悬挂在所述无接箍油管 悬挂器 208。 也可以说， 注蒸汽管柱和机械举升管柱都直接悬挂在厚法兰密封主体 209 上， 为井口原有的油管悬挂器， 这一点与现有技术是相同的， 但除此之外， 本发明还在 厚法兰密封主体 209上悬挂了无接箍油管悬挂器 208， 用于固定和连接连续油管 110。 为了保证在井口阀门***的有限空间内能够同时连接或悬挂三个管柱或管道，本发 明在厚法兰密封主体 209上除了开设蒸汽入口 202夕卜，还为无接箍油管悬挂器 208的设 置留出了空间， 使得二者或不影响， 互不干涉， 无接箍油管悬挂器 208设置在蒸汽入口 202的侧向， 从图 3上看， 无接箍油管悬挂器 208设置在蒸汽入口 202的后方。
本发明实现了同井筒内的注汽、 采油、 监测， 使得注汽、 采油、 监测可在同一井筒 内同时进行， 而现有技术仅仅为吞吐开发进行的注汽和监测， 需要在注汽结束后提出注 汽与监测管柱、 下入采油管柱后才能进行采油作业。
进一步地， 如图 2， 所述三管同井筒采油工艺设备还包括： 抽油泵 104， 连接在所 述机械举升管柱 103的下底端，用于抽取水平井中的蒸汽冷凝水及蒸汽冷凝水中掺杂的 原油。所述抽油泵的活塞与抽油杆采用抽油杆脱接器连接。所述抽油泵下入深度 L满足：
L^H-lOO (P-l)
其中， H为油层垂直深度， P 为地层压力。 进一步地，如图 2，所述三管同井筒采油工艺设备还包括：水平井的筛管悬挂器 106， 设置在所述技术套管中， 于悬挂水平井水平段的筛管， 末端筛 105位于筛管的末端， 用 于向所述技术套管的水平段注入蒸汽。
进一步地， 如图 5， 所述注蒸汽管柱最大外径、 机械举升管柱及无接箍油管最大外 径之和比所述技术套管的垂直段的内径至少小 10mm，以保证三个管柱或管道都能安装在 技术套管中。 进一步地， 所述技术套管的垂直部分的内径 220mm， 以保证三个管柱或 管道都能安装在技术套管中。
进一步地，所述无接箍油管的内径应至少大于 40mm，所述连续油管的内径应至少小 于 38mm， 以便无接箍油管容纳连续油管。
进一步地， 所述技术套管的垂直部分的内径 220mm， 所述机械举升管柱的最大外 径 70皿，这样，能够减小机械举升管柱的外径尺寸，增加其他两个管柱或管道的空间， 进一步地，所述抽油泵本体及抽油泵接箍的最大外径均 92mm，以获得合理的空间分配。 所述机械举升管柱的内径 62mm， 以保证举升效率。 进一步地， 所述注蒸汽管柱的内径 ^40mm, 以保证注汽质量。
进一步地，所述注蒸汽管柱的接箍的外径与无接箍油管的最大外径之和比所述技术 套管的水平段的内径至少小 10mm， 以使得注蒸汽管柱能够设置在技术套管的水平段中。
作为较佳的选择， 所述注蒸汽管柱 102的内径 40mm， 外径 89mm; 所述注蒸汽管 柱 102的接箍的外径比所述技术套管的水平段的内径至少小 10mm，较佳地，所述注蒸汽 管柱的接箍的外径 108mm， 所述接箍采用双向倒角连接。
较佳地， 所述机械举升管柱 103的外径 70讓， 内径 62讓； 所述注蒸汽管柱 102 的最大外径与机械举升管 103柱的最大外径之和比所述技术套管 101的垂直部分的内径 至少小 10mm， 机械举升管柱 103的接箍大约为 89mm。
进一步地，通过机械举升强制循环，蒸汽不激励进入油层，传热方式以热传导为主， 仅靠蒸汽与地层 （或油层）温度的温差引起的热传导传热方式加热地层； 采出液为注入 的蒸汽冷却后形成的冷凝水， 采注比保持在 1. 0。
进一步地， 所述步骤 A具体为步骤 A2: 选择合格油藏， 所述合格油藏的地质参数满 足以下条件： 油藏埋深 680米， 50°C下脱气原油粘度为 147500〜485400mPa. s， 连续油 层厚度为 80米。
下面更为详细的描述几个具体实例：
实例 1 : 某油藏的一砂岩组油层， 即为砂岩组油藏， 埋深 955米， 50°C下脱气原油 粘度为 53450〜72340mPa. s， 油层厚度为 15米， 在直井蒸汽吞吐末期， 油藏区域内部署 2个成对水平井井组， 包括 2口水平注汽井、 2口水平生产井， 1口水平观察井， 水平井 方向与构造线基本保持平行， 上下水平井间距离为 5米。 针对该油藏的地质特征和原油 性质， 开展了双水平井井对的循环预热试验。
油层平均厚度大于 15米， 孔隙度， 渗透率， 垂向渗透率与水平方向渗透率比值大 于 0. 3， 适合 SAGD技术开采；
未开发油藏， 布井方式为双水平井组， 上下水平井间距 5米；
在上下水平井井筒内分别下入注汽管柱、 举升管柱和举升设备， 同时在上水平井下 入光纤测温***， 监测水平段温度变化；
在注汽管柱内注入湿饱和蒸汽， 利用举升设备回采， 强制蒸汽循环， 注汽速率为 110t/d, 井口干度为 95%， 单井注汽 10000t， 循环预热 4个月， 采注比在 1. 0。
上水平井光纤测温监测资料显示，下水平井注汽后，上水平井水平段温度逐渐升高， 热连通井段 260m， 占总水平段的 58%， 表明两口井之间正在逐步连通。
实例 2: 某油田馆陶组油层为中深层超稠油油藏， 埋深 680米， 50°C下脱气原油粘 度为 147500〜485400mPa. s， 油层厚度为 80米。在本发明之前， 该油藏采用双水平井组 合方式， 其生产历程划分为吞吐及吞吐预热两个阶段， 在吞吐阶段， 下水平井吞吐四周 期， 上水平井投产后， 井组吞吐预热二周期。 周期产油量和油汽比均在下降， 采出程度 为 18%。 针对该油藏的地质特征和原油性质， 本发明实施了上下水平井的循环预热。
( 1 ) 油层平均厚度大于 15米， 孔隙度， 渗透率， 垂向渗透率与水平方向渗透率比 值大于 0. 3， 适合 SAGD技术开采；
( 2 ) 已开发油藏， 布井方式为双水平井组合， 上下水平井间距 4米；
( 3 ) 在上下水平井井筒内均下入注汽管柱、 举升管柱和举升设备；
( 4) 在注汽管柱内注入湿饱和蒸汽， 利用举升设备回采， 强制蒸汽循环， 工作注 汽速率为 110t/d， 井口干度为 95%， 单井注汽 10000t， 循环预热 4个月， 采注比在 1. 0。
该井组通过等温差循环预热使未达到均匀动用的 2/3水平段得到均匀动用，全部水 平段温度均达到 150°C。 并且转入 SAGD开发后， 取得了较好的效果。 上水平井转注， 日 注汽 180吨， 下水平井采用 Φ 120πιπι泵开井生产， 井组日产液 184吨， 日产油 40. 3吨， 含水 78. 2%， 瞬时油汽比 0. 19， 瞬时采注比 0. 87。 SAGD阶段注汽 43164吨， 阶段产液 48858吨，阶段产油 7042吨，阶段油汽比 0. 16，阶段采注比 1. 13，平均日产油 32. 8t/d, 超过前吞吐预热平均日产油量。
本发明能解决中深层超稠油油藏水平井因储层非均质造成的动用不均、预热启动难 的问题， 对提高 SAGD初期水平段的利用效率和加快 SAGD的产油速率起到重要促进。
以上所述仅为本发明示意性的具体实施方式， 并非用以限定本发明的范围。 为本发 明的各组成部分在不冲突的条件下可以相互组合， 任何本领域的技术人员， 在不脱离本 发明的构思和原则的前提下所作出的等同变化与修改， 均应属于本发明保护的范围。

Claims

权利要求书
1、 一种中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特征在于， 所述中 深层油藏双水平井等温差强制蒸汽循环预热方法包括：
步骤 A : 选择合格油藏， 所述合格油藏的地质参数满足以下条件： 油藏埋深为
600-1000m, 连续油层厚度大于等于 10m， 垂向渗透率与水平渗透率比例大于 0. 3 ;
步骤 B: 在所述合格油藏中设置双水平井， 所述双水平井包括： 井距为 4-6m的上 水平井和下水平井， 双水平井的井深小于 1600米， 双水平的水平段长度在 300m以上； 步骤 C: 对上水平井和下水平井同时进行蒸汽吞吐开发， 使所述合格油藏降压至 3. 5MPa以下；
步骤 D: 然后， 在所述双水平井的上水平井中下入上水平井注汽管柱和上水平井机 械举升管柱， 上水平井注汽管柱下深到上水平井水平段的 2/3处， 在所述双水平井的下 水平井中下入下水平井注汽管柱和下水平井机械举升管柱， 下水平井注汽管柱下深到下 水平井水平段的脚尖处；
步骤 E: 然后循环预热， 上水平井和下水平井同时进行连续的注入采出， 将蒸汽在 上水平井和下水平井内同时注入， 同时利用机械举升回采冷凝液， 上水平井内的冷凝液 由上水平井采出， 下水平井的冷凝液由下水平井采出。
2、 如权利要求 1所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于， 中深层油藏双水平井等温差强制蒸汽循环预热方法还包括： 步骤 F: 在循环预 热 2至 4个月后， 转为蒸汽辅助重力泄油开发， 注汽井注汽， 生产井降压生产， 其中， 上水平井为注汽井， 下水平井为生产井。
3、 如权利要求 1所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于， 步骤 C 中， 上水平井和下水平井同时进行蒸汽吞吐开发使油藏降压至 3 至 3. 5MPa。
4、 如权利要求 1所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于， 所述合格油藏的油藏区块中的超稠油流体特性为： 油层温度下脱气原油粘度大 于 50000mPa* s， 相对密度大于 0. 98g/cm3。
5、 如权利要求 2所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于， 步骤 F具体包括： 待注汽井和生产井之间的温度大于 90 °C， 注汽井的水平段和 生产井的水平段的 80%以上区域温度达到 150 °C时， 转入蒸汽辅助重力泄油开发。
6、 如权利要求 2所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于，
所述步骤 A具体为步骤 A1 : 选择合格油藏， 所述合格油藏的地质参数满足以下条 件： 油藏埋深为 995m， 50°C下脱气原油粘度为 53450〜72340mPa. s， 连续油层厚度等于 15m;
所述步骤 B具体为步骤 B1 : 在所述合格油藏中设置两个成对的双水平井， 每对所 述双水平井包括： 井距为 5m的上水平井和下水平井；
所述步骤 E具体为步骤 E1 : 工作注汽速率为 110t/d， 井口干度为 95%， 单井注汽 10000t,
所述步骤 F具体为步骤 F1 : 循环预热 4个月， 采注比在 0. 8至 1. 2之间。
7、 如权利要求 1所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于， 所述步骤 D还包括步骤 D1 : 所述上水平井做为监测井， 在所述上水平井下入光 纤测温***。
8、 如权利要求 1所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于，
通过机械举升强制循环， 蒸汽不激励进入油层， 传热方式以热传导为主， 仅靠蒸 汽与地层温度的温差引起的热传导传热方式加热地层； 采出液为注入的蒸汽冷却后形成 的冷凝水， 采注比保持在 1. 0。
9、 如权利要求 1所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其特 征在于，
所述步骤 A具体为步骤 A2: 选择合格油藏， 所述合格油藏的地质参数满足以下条 件： 油藏埋深 680米， 50°C下脱气原油粘度为 147500〜485400mPa. s， 连续油层厚度为 80米。
10、 如权利要求 1 所述的中深层油藏双水平井等温差强制蒸汽循环预热方法， 其 特征在于， 上水平井机械举升管柱设置在所述上水平井的造斜段， 下水平井机械举升管 柱设置在所述下水平井的造斜段。
PCT/CN2013/088023 2013-11-28 2013-11-28 中深层油藏双水平井等温差强制蒸汽循环预热方法 WO2015077954A1 (zh)

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