A system and method for realizing integrated heavy oil injection and production through small oil pipe casting and fishing electric pump

Abstract

The present invention discloses an integrated system for heavy oil injection and production by using a small oil pipe to launch and salvage an electric pump, comprising an outer heat injection string and an inner production string, wherein the production string comprises a small oil pipe, an electric submersible pump connector, and an inverted electric submersible pump from top to bottom, and the electric submersible pump connector is provided with a second guide flow hole. The present application involves less ground operation equipment, high operation efficiency, and saves operation resources and costs; a small oil pipe is selected as the output fluid output channel to avoid fluid immersion and scouring in the annulus between the inner production string and the outer heat injection string, thereby protecting the thermal insulation performance of the insulated oil pipe and the insulation performance of the cable, and reducing the risk of failure; the electric submersible pump unit adopts an inverted pump design, and the cable is directly connected to the electric submersible pump motor after passing through the upper production packer, reducing the risk of cable crushing and improving the operating stability of the electric submersible pump in highly deviated wells; the small oil pipe has a strong launching and salvaging capability, and can realize launching and salvaging of the electric submersible pump in highly deviated wells and horizontal wells.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore heavy oil thermal recovery, and in particular to a system and method for realizing heavy oil injection and production integration by casting and fishing electric pumps through small oil pipes. Background Art

[0002] Offshore oilfields are rich in heavy oil resources, and steam stimulation is an important means of improving oil recovery. Existing steam stimulation and injection-production integration is primarily achieved through two process approaches. The first, such as patent application number 202210768088.6, discloses a method for integrated injection-production by deploying and hauling electric pumps. After heat injection, well shut-down, and blowdown, a composite pipe and cable is used to deploy an electric submersible pump (ESP) into the heat injection string for production. After production is complete, the ESP is pulled out for a new round of heat injection. This process saves one pipe string operation and improves steam stimulation efficiency. However, it requires a dedicated Christmas tree, and the continuous pipe and cable require numerous surface supporting equipment, occupying a large area, limiting its application on offshore platforms. The produced fluid channel is an insulated oil pipe, which can degrade due to long-term erosion and soaking. Using an upright pump, the unit's small flat cable must cross a larger centrifugal pump to connect to the motor, which can easily cause the small flat cable to collapse in highly deviated wells. The deploying and hauling capacity of the composite pipe and cable is significantly affected by well inclination, making it less adaptable in highly deviated wells. The second type, such as the patent with application number 202010095172.7, discloses an offshore heavy oil steam injection and production integrated device. A Y-string is lowered, the oil pipe uses an insulated oil pipe, and the electric submersible pump uses a high-temperature electric submersible pump. During the completion stage, the string and the electric submersible pump are directly lowered into the wellbore. An injection-production conversion valve is designed on the string to switch the injection / production channel. This process can achieve integrated injection and production without moving the string, but it has extremely high requirements on the high-temperature resistance of the electric submersible pump. At present, the high-temperature electric submersible pump is still in the research and development and improvement stage, and has not yet entered large-scale application. Summary of the Invention

[0003] The present invention provides a system and method for realizing integrated heavy oil injection and production by dropping and fishing an electric pump with a small oil pipe. Insulated oil pipes are run into the casing for heat injection. After the well is soaked and the blowout is completed, the electric submersible pump is inverted by dropping and fishing the small oil pipe to realize integrated injection and production. The operation can be completed by using a platform workover rig without the need for additional equipment, saving operating costs, and reducing the risk of crushing the small flat cable of the electric submersible pump. The system has good adaptability in highly deviated wells and horizontal wells.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] A system for integrating heavy oil injection and production by using a small oil pipe and electric pump, comprising:

[0006] A heat injection string, the heat injection string is arranged in the casing, the heat injection string includes, from top to bottom, a first insulated oil pipe, a perforated pipe, and a second insulated oil pipe, a high-temperature packer is provided between the first insulated oil pipe and the casing, the high-temperature packer is provided with an air release valve, the perforated pipe is provided with a first guide hole, the first guide hole is used to connect the inner cavity of the perforated pipe with the outer heat injection string and the casing annulus, the second insulated oil pipe is provided with a deep well safety valve, the second insulated oil pipe below the deep well safety valve extends into the sand control string, and the diameter of the first insulated oil pipe is larger than the diameter of the second insulated oil pipe;

[0007] a production tubing string adapted to be lowered into the first insulated tubing, the production tubing string comprising, from top to bottom, a small tubing, an electric submersible pump connector, and an inverted electric submersible pump; an upper production packer disposed between the small tubing and the first insulated tubing; a lower production packer disposed between the inverted electric submersible pump and the first insulated tubing; and a second flow-through hole disposed on the electric submersible pump connector for connecting an inner cavity of the small tubing with an outer heat injection tubing string and an annulus of an inner production tubing string;

[0008] When injecting the hot fluid, the hot fluid passes through the first insulated oil pipe, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation;

[0009] During gas injection, the gas passes through the Christmas tree wing valve, the first insulated oil pipe and casing annulus, the bleed valve, the first insulated oil pipe and casing annulus, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation;

[0010] When producing through the inner production tubing, the formation production fluid passes through the formation, the second insulated oil pipe, the deep well safety valve, the second insulated oil pipe, the perforated pipe, the inverted electric submersible pump, the inverted electric submersible pump and the annulus of the first insulated oil pipe, and the electric submersible pump connector to the small oil pipe for production.

[0011] Optionally, the electric submersible pump connector includes an upper connecting pipe and a lower connecting pipe, the upper connecting pipe is provided with an upper interface for connecting a small oil pipe, the side wall of the upper connecting pipe is provided with the second diversion flow hole, the lower connecting pipe is provided with a lower interface for connecting an inverted electric submersible pump, and a partition plate is provided between the upper connecting pipe and the lower connecting pipe.

[0012] Optionally, the inverted electric submersible pump includes, from top to bottom, a motor, a protector, a centrifugal pump outlet, a centrifugal pump, a centrifugal pump inlet, and a flow guide pipe, wherein the motor is connected to the lower interface of the lower connecting pipe, the centrifugal pump outlet is used to connect the centrifugal pump with the outer heat injection string and the inner production string annulus, the centrifugal pump inlet is used to connect the inner cavity of the flow guide pipe and the centrifugal pump, and a gas separator is provided on the flow guide pipe;

[0013] The formation produced fluid is produced through the formation, the second insulated oil pipe, the deep well safety valve, the second insulated oil pipe, the perforated pipe, the diversion pipe, the centrifugal pump inlet, the centrifugal pump, the centrifugal pump outlet, the inverted electric submersible pump and the first insulated oil pipe annulus, and the electric submersible pump connector to the small oil pipe.

[0014] Optionally, the lower production packer is arranged outside the flow guide tube and is located below the gas separator and above the perforated tube.

[0015] Optionally, the upper production packer and the lower production packer are both hydraulically sealed and unsealed by lifting the tubing string, and the upper production packer and the lower production packer share a production packer hydraulic control pipeline, and the upper production packer and the lower production packer are communicatively connected to the ground control equipment through the production packer hydraulic control pipeline.

[0016] Optionally, the high-temperature packer is hydraulically sealed and unsealed by lifting the tubing string. The high-temperature packer is communicatively connected to the ground control equipment via the high-temperature packer hydraulic control pipeline. The air release valve is communicatively connected to the ground control equipment via the air release valve hydraulic control pipeline. The deep well safety valve is connected to the ground control equipment via the deep well safety valve hydraulic control pipeline.

[0017] Optionally, the first heat-insulated oil pipe is sealed and hung in the casing through a large oil pipe hanger, and the small oil pipe is sealed and hung at the spool position of the Christmas tree through a small oil pipe hanger.

[0018] Optionally, the high-temperature packer hydraulic control pipeline, the deep well safety valve hydraulic control pipeline, and the air release valve hydraulic control pipeline are fixed to the outer wall of the first insulated oil pipe through a pipeline protector, pass through the large oil pipe hanger and then pass through the oil production tree as a whole. The production packer hydraulic control pipeline and the cable of the inverted electric submersible pump are fixed to the outer wall of the small oil pipe through a pipeline protector, pass through the small oil pipe hanger and then pass through the oil production tree as a whole.

[0019] A method for realizing the aforementioned integrated system of heavy oil injection and production by using a small oil pipe to cast and retrieve an electric pump, comprising:

[0020] S1: Open the deep well safety valve and the bleed valve, set the high-temperature packer, inject hot fluid into the well using the heat injection string, and inject gas using the heat injection string and the casing annulus. When injecting hot fluid, the hot fluid passes through the first insulated oil pipe, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation; when injecting gas, the gas passes through the Christmas tree wing valve, the first insulated oil pipe and the casing annulus, the bleed valve, the first insulated oil pipe and the casing annulus, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation. After the heat injection is completed, the well enters the soaking and blowing stages in sequence. During the blowing stage, the formation fluid flows out to the wellhead through the heat injection string.

[0021] S2: After the blowout is completed, the inverted pump is put into the first insulated tubing through the small tubing, the upper production packer and the lower production packer are set, the pump is started, and the produced fluid is lifted to the wellhead. The formation produced fluid passes through the formation, the second insulated tubing, the deep well safety valve, the second insulated tubing, the perforated pipe, the flow guide pipe, the centrifugal pump inlet, the centrifugal pump, the centrifugal pump outlet, the inverted electric submersible pump and the annulus of the first insulated tubing, and the electric submersible pump connector to the small tubing for output;

[0022] S3: When the ESP production drops to the economic level, stop the pump, release the upper and lower production packers, and pull out the inverted pump unit through the small tubing.

[0023] S4: Repeat step S1 again.

[0024] Optionally, the tubing operation can be completed by a workover rig when the inverted pump unit is put in and pulled out through a small oil pipe.

[0025] In summary, the technical effects and advantages of the present invention are:

[0026] 1) Achieve steam injection-production conversion through a single string movement operation, involving less ground operation equipment, high operation efficiency, and saving operation resources and costs;

[0027] 2) Use small oil pipes as the production channel for produced fluids to avoid immersion and erosion of fluid in the annulus between the inner production string and the outer heat injection string. This can protect the thermal insulation performance of the insulated oil pipe and the insulation performance of the cable, reducing the risk of failure.

[0028] 3) The ESP unit adopts an inverted pump design. The cable passes through the upper production packer and is directly connected to the ESP motor. This reduces the risk of cable collapse and improves the operational stability of the ESP in highly deviated wells.

[0029] 4) By optimizing the flow path of produced fluids, gas in the produced fluids can be discharged in a timely manner, avoiding the accumulation of gas at the ESP location, which may lead to unstable production or gas lock.

[0030] 5) The small tubing casting and fishing capability is strong, and can realize the casting and fishing of electric submersible pumps in highly deviated wells and horizontal wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1This is a structural diagram of a system for realizing integrated heavy oil injection and production by using a small oil pipe casting and bailing electric pump in one embodiment of the present invention;

[0033] Figure 2 This is a schematic structural diagram of an electric submersible pump connector according to an embodiment of the present invention;

[0034] Figure 3 This is a hot fluid flow path when injecting heat through the outer heat injection string in one embodiment of the present invention;

[0035] Figure 4 The nitrogen injection flow route through the outer heat injection string-casing annulus in one embodiment of the present invention;

[0036] Figure 5 This is the flow path of the formation production fluid during production through the inner production string in one embodiment of the present invention.

[0037] Among them: 1. Casing; 2. Large tubing hanger; 3. First insulated tubing; 4. Hydraulic control line for air release valve; 5. Hydraulic control line for high-temperature packer; 6. Air release valve; 7. High-temperature packer; 8. Perforated pipe; 9. Second insulated tubing; 10. Deep well safety valve; 11. Sand control string; 12. Small tubing hanger; 13. Small tubing; 14. Cable; 15. Upper production packer; 16. Electric submersible pump connector; 16-1. Upper connecting pipe; 16-2. Second diversion hole; 16-3. Lower connecting pipe; 17. Motor; 18. Protector; 19. Hydraulic control line for production packer; 20. Liquid outlet of electric submersible pump; 21. Centrifugal pump; 22. Liquid inlet of centrifugal pump; 23. Diversion pipe; 24. Gas separator; 25. Lower production packer; 26. Hydraulic control line for deep well safety valve. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] This embodiment proposes a system for realizing the integrated injection and production of heavy oil by using a small oil pipe and electric pump. Figure 1-Figure 5As shown, it includes a heat injection string and a production string. The heat injection string is arranged in the casing 1. The heat injection string includes a first insulated oil pipe 3, a perforated pipe 8 and a second insulated oil pipe 9 from top to bottom. A high-temperature packer 7 is provided between the first insulated oil pipe 3 and the casing 1. A bleed valve 6 is provided on the high-temperature packer 7. The high-temperature packer 7 divides the annulus of the outer heat injection string and the casing 1 into two parts, upper and lower. When the bleed valve 6 is opened, gas can pass through the bleed valve 6 into the annulus below the high-temperature packer 7. The annulus of the first insulated oil pipe 3 and the casing 1; the perforated pipe 8 is provided with a first guide flow hole, which is used to connect the inner cavity of the perforated pipe 8 with the outer heat injection pipe string and the annulus of the casing 1; the second insulated oil pipe 9 is provided with a deep well safety valve 10, and the second insulated oil pipe 9 below the deep well safety valve 10 extends into the sand control pipe string 11, and sealing is achieved by positioning sealing. The diameter of the first insulated oil pipe 3 is larger than the diameter of the second insulated oil pipe 9, which is convenient for running in and out of the production pipe string.

[0041] The production string is suitable for being lowered into the first insulated oil tubing 3. The production string includes, from top to bottom, a small oil tubing 13, an electric submersible pump connector 16, and an inverted electric submersible pump. An upper production packer 15 is provided between the small oil tubing 13 and the first insulated oil tubing 3. When the packer is set, the annulus between the first insulated oil tubing 3 and the small oil tubing 13 is isolated into two parts, upper and lower. A lower production packer 25 is provided between the inverted electric submersible pump and the first insulated oil tubing 3. When the packer is set, the annulus between the first insulated oil tubing 3 and the inverted electric submersible pump is isolated into two parts, upper and lower. The electric submersible pump connector 16 is provided with a second flow-through hole 16-2. The second flow-through hole 16-2 is used to connect the inner cavity of the small oil tubing 13 with the outer heat injection string and the inner production string annulus.

[0042] When injecting hot fluid, Figure 3 As shown, the hot fluid passes through the first insulated oil pipe 3, the perforated pipe 8, the second insulated oil pipe 9, the deep well safety valve 10, and the second insulated oil pipe 9 to the formation.

[0043] When injecting gas, Figure 4 As shown, the gas passes through the tree wing valve, the first insulated oil pipe 3 and the annulus of the casing 1, the bleed valve 6, the first insulated oil pipe 3 and the annulus of the casing 1, the perforated pipe 8, the second insulated oil pipe 9, the deep well safety valve 10, and the second insulated oil pipe 9 to the formation; this embodiment relies on the existing oil tree structure design, and the oil tree belongs to the existing structure and is not described here.

[0044] When producing through the inner production string, if Figure 5 As shown, the formation production fluid is produced through the formation, the second insulated oil pipe 9, the deep well safety valve 10, the second insulated oil pipe 9, the perforated pipe 8, the inverted electric submersible pump, the inverted electric submersible pump and the annulus of the first insulated oil pipe 3, and the electric submersible pump connector 16 to the small oil pipe 13.

[0045] This embodiment realizes the injection-production conversion of the steam huff-and-puff process through a single tubing operation, involves less ground operation equipment, has high operation efficiency, and saves operation resources and costs; a small oil pipe 13 is selected as the output channel of the produced fluid to avoid the immersion and scouring of the fluid in the annulus between the inner production pipe string and the outer heat injection pipe string, which can protect the thermal insulation performance of the insulated oil pipe on the one hand, and the insulation performance of the cable 14 on the other hand, reducing the risk of failure; the electric submersible pump unit adopts an inverted pump design, and the cable 14 is directly connected to the electric submersible pump motor 17 after passing through the upper production packer 15, reducing the risk of cable 14 being crushed and improving the operating stability of the electric submersible pump in highly deviated wells; the small oil pipe 13 has a strong launching and fishing capability, which can realize the launching and fishing of the electric submersible pump in highly deviated wells and horizontal wells.

[0046] Alternatively, as Figure 2 As shown, the electric submersible pump connector 16 includes an upper connecting pipe 16-1 and a lower connecting pipe 16-3. The upper connecting pipe 16-1 is provided with an upper interface for connecting to the small oil pipe 13. The side wall of the upper connecting pipe 16-1 is provided with the second guide flow hole 16-2. The lower connecting pipe 16-3 is provided with a lower interface for connecting to an inverted electric submersible pump. A partition plate is provided between the upper connecting pipe 16-1 and the lower connecting pipe 16-3, and the partition plate prevents the upper connecting pipe 16-1 and the lower connecting pipe 16-3 from communicating with each other.

[0047] Optionally, the inverted electric submersible pump includes, from top to bottom, a motor 17, a protector 18, a centrifugal pump outlet 20, a centrifugal pump 21, a centrifugal pump inlet 22 and a guide pipe 23, wherein the motor 17 is connected to the lower interface of the lower connecting pipe 16-3, the centrifugal pump outlet 20 is used to connect the centrifugal pump 21 with the outer heat injection pipe string and the inner production pipe string annulus, the centrifugal pump inlet 22 is used to connect the inner cavity of the guide pipe 23 and the centrifugal pump 21, and a gas separator 24 is provided on the guide pipe 23; the gas separator 24 is used to separate the gas in the formation production fluid and drain the liquid to the centrifugal pump inlet 22 through the guide pipe 23.

[0048] like Figure 5 As shown, the formation produced fluid is produced through the formation, the second insulated oil pipe 9, the deep well safety valve 10, the second insulated oil pipe 9, the perforated pipe 8, the diversion pipe 23, the centrifugal pump inlet 22, the centrifugal pump 21, the centrifugal pump outlet 20, the inverted electric submersible pump and the annulus of the first insulated oil pipe 3, the electric submersible pump connector 16 to the small oil pipe 13.

[0049] Optionally, the lower production packer 25 is disposed outside the flow tube 23, below the gas separator 24 and above the perforated pipe 8. The lower production packer 25 is located below the gas separator 24, allowing the gas separated by the gas separator 24 to be discharged into the annulus between the inverted pump and the first insulated oil pipe 3. This embodiment optimizes the flow path of the produced fluid, allowing gas in the produced fluid to be discharged promptly, thereby preventing gas accumulation at the electric submersible pump location, leading to unstable fluid production or gas lock.

[0050] Optionally, both the upper production packer 15 and the lower production packer 25 are hydraulically set and released by pulling up the tubing string, and the upper production packer 15 is designed without slips. The upper production packer 15 and the lower production packer 25 share a production packer hydraulic control line 19, and the upper production packer 15 and the lower production packer 25 are communicatively connected to the surface control equipment via the production packer hydraulic control line 19.

[0051] Optionally, the high-temperature packer 7 is hydraulically sealed and unsealed by lifting the tubing string. The high-temperature packer 7 is communicated with the ground control equipment through the high-temperature packer hydraulic control pipeline 5. The air release valve 6 is communicated with the ground control equipment through the air release valve hydraulic control pipeline 4. The deep well safety valve 10 is connected to the ground control equipment through the deep well safety valve hydraulic control pipeline 26.

[0052] Optionally, the first insulated oil pipe 3 is sealed and hung in the casing 1 via a large oil pipe hanger 2, and the small oil pipe 13 is sealed and hung at the spool position of the Christmas tree via a small oil pipe hanger 12. In this embodiment, the Christmas tree is of an existing structure.

[0053] Optionally, the high-temperature packer hydraulic control pipeline 5, the deep well safety valve hydraulic control pipeline 26, and the air release valve hydraulic control pipeline 4 are fixed to the outer wall of the first insulated oil pipe 3 through a pipeline protector, pass through the large oil tubing hanger 2, and then pass through the oil production tree as a whole. The production packer hydraulic control pipeline 19 and the inverted electric submersible pump cable 14 are fixed to the outer wall of the small oil tubing 13 through a pipeline protector, pass through the small oil tubing hanger 12, and then pass through the oil production tree as a whole.

[0054] This embodiment also provides a method for implementing the aforementioned heavy oil injection and production integrated system by dropping and hauling an electric pump through the small oil pipe 13, comprising:

[0055] S1: Open the deep well safety valve 10 and the bleed valve 6, set the high-temperature packer 7, inject hot fluid into the well using the heat injection string, and inject gas using the heat injection string and the annulus of the casing 1. When injecting hot fluid, the hot fluid passes through the first insulated oil pipe 3, the perforated pipe 8, the second insulated oil pipe 9, the deep well safety valve 10, and the second insulated oil pipe 9 to the formation; when injecting gas, the gas passes through the Christmas tree wing valve, the first insulated oil pipe 3 and the annulus of the casing 1, the bleed valve 6, the first insulated oil pipe 3 and the annulus of the casing 1, the perforated pipe 8, the second insulated oil pipe 9, the deep well safety valve 10, and the second insulated oil pipe 9 to the formation. After the heat injection is completed, the well enters the soaking stage and the blowing stage in sequence. During the blowing stage, the formation fluid is blown out to the wellhead through the heat injection string. In this embodiment, the gas is nitrogen, and this application does not limit the specific type of gas.

[0056] S2: After the blowout is completed, the inverted pump is put into the first insulated oil pipe 3 through the small oil pipe 13, the upper production packer 15 and the lower production packer 25 are set, the pump is started, and the produced fluid is lifted to the wellhead. The formation produced fluid passes through the formation, the second insulated oil pipe 9, the deep well safety valve 10, the second insulated oil pipe 9, the perforated pipe 8, the diversion pipe 23, the centrifugal pump inlet 22, the centrifugal pump 21, the centrifugal pump outlet 20, the inverted electric submersible pump and the annulus of the first insulated oil pipe 3, and the electric submersible pump connector 16 to the small oil pipe 13 for production;

[0057] S3: When the output of the electric submersible pump drops to the economic output, the pump is stopped, the upper production packer 15 and the lower production packer 25 are unsealed, and the inverted pump unit is pulled out through the small oil pipe 13;

[0058] S4: Repeat step S1 again.

[0059] Optionally, the tubing string operation can be completed by a workover rig when the inverted pump unit is put into or pulled out through the small oil pipe 13.

[0060] For ease of description, spatially relative terms such as "upper," "lower," "outer," and "inner" are used in the embodiments to describe the relationship of one element or feature relative to another element or feature shown in the figures. It should be understood that these spatial terms are intended to encompass different orientations of the device during use or operation in addition to the orientation shown in the figures. Thus, the exemplary term "lower" encompasses both upper and lower orientations.

[0061] Furthermore, relational terms such as "3" and "4" etc. are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any such actual relationship or order between these components.

[0062] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms of specific changes without departing from the scope of protection of the invention and the claims. These all fall within the scope of protection of the present invention.

Claims

1. A system for integrating heavy oil injection and production by using a small oil pipe and an electric pump, characterized in that: include: A heat injection string, the heat injection string is arranged in the casing, the heat injection string includes, from top to bottom, a first insulated oil pipe, a perforated pipe, and a second insulated oil pipe, a high-temperature packer is provided between the first insulated oil pipe and the casing, the high-temperature packer is provided with an air release valve, the perforated pipe is provided with a first guide hole, the first guide hole is used to connect the inner cavity of the perforated pipe with the outer heat injection string and the casing annulus, the second insulated oil pipe is provided with a deep well safety valve, the second insulated oil pipe below the deep well safety valve extends into the sand control string, and the diameter of the first insulated oil pipe is larger than the diameter of the second insulated oil pipe; a production tubing string adapted to be lowered into the first insulated tubing, the production tubing string comprising, from top to bottom, a small tubing, an electric submersible pump connector, and an inverted electric submersible pump; an upper production packer disposed between the small tubing and the first insulated tubing; a lower production packer disposed between the inverted electric submersible pump and the first insulated tubing; and a second flow-through hole disposed on the electric submersible pump connector for connecting an inner cavity of the small tubing with an outer heat injection tubing string and an annulus of an inner production tubing string; When injecting the hot fluid, the hot fluid passes through the first insulated oil pipe, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation; During gas injection, the gas passes through the Christmas tree wing valve, the first insulated oil pipe and casing annulus, the bleed valve, the first insulated oil pipe and casing annulus, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation; When producing through the inner production tubing, the formation production fluid passes through the formation, the second insulated oil pipe, the deep well safety valve, the second insulated oil pipe, the perforated pipe, the inverted electric submersible pump, the inverted electric submersible pump and the annulus of the first insulated oil pipe, and the electric submersible pump connector to the small oil pipe for production.

2. The integrated system for heavy oil injection and production by using a small oil pipe and electric pump according to claim 1 is characterized in that: The electric submersible pump connector includes an upper connecting pipe and a lower connecting pipe. The upper connecting pipe is provided with an upper interface for connecting a small oil pipe. The side wall of the upper connecting pipe is provided with the second guide flow hole. The lower connecting pipe is provided with a lower interface for connecting an inverted electric submersible pump. A partition plate is provided between the upper connecting pipe and the lower connecting pipe.

3. The system for realizing integrated heavy oil injection and production by using a small oil pipe and electric pump according to claim 2, characterized in that: The inverted electric submersible pump includes, from top to bottom, a motor, a protector, a centrifugal pump outlet, a centrifugal pump, a centrifugal pump inlet, and a flow guide pipe. The motor is connected to the lower interface of the lower connecting pipe. The centrifugal pump outlet is used to connect the centrifugal pump with the outer heat injection string and the inner production string annulus. The centrifugal pump inlet is used to connect the inner cavity of the flow guide pipe and the centrifugal pump. A gas separator is provided on the flow guide pipe. The formation produced fluid is produced through the formation, the second insulated oil pipe, the deep well safety valve, the second insulated oil pipe, the perforated pipe, the diversion pipe, the centrifugal pump inlet, the centrifugal pump, the centrifugal pump outlet, the inverted electric submersible pump and the first insulated oil pipe annulus, and the electric submersible pump connector to the small oil pipe.

4. The integrated system for heavy oil injection and production by using a small oil pipe and electric pump according to claim 3 is characterized in that: The lower production packer is arranged outside the flow guide pipe and is located below the gas separator and above the perforated pipe.

5. The integrated system for heavy oil injection and production by using a small oil pipe and electric pump according to claim 1 is characterized in that: The upper production packer and the lower production packer are both hydraulically sealed and unsealed by lifting the tubing string. The upper production packer and the lower production packer share a production packer hydraulic control pipeline. The upper production packer and the lower production packer are communicated with the ground control equipment through the production packer hydraulic control pipeline.

6. The integrated system for heavy oil injection and production by using a small oil pipe and electric pump according to claim 5 is characterized in that: The high-temperature packer is hydraulically sealed and unsealed by lifting the tubing string. The high-temperature packer is communicated with the ground control equipment through the high-temperature packer hydraulic control pipeline. The air release valve is communicated with the ground control equipment through the air release valve hydraulic control pipeline. The deep well safety valve is connected to the ground control equipment through the deep well safety valve hydraulic control pipeline.

7. The integrated system for heavy oil injection and production by using a small oil pipe and electric pump according to claim 6 is characterized in that: The first heat-insulated oil pipe is sealed and hung in the casing through a large oil pipe hanger, and the small oil pipe is sealed and hung at the spool position of the Christmas tree through a small oil pipe hanger.

8. The integrated system for heavy oil injection and production by using a small oil pipe and electric pump according to claim 7 is characterized in that: The high-temperature packer hydraulic control pipeline, deep well safety valve hydraulic control pipeline, and air release valve hydraulic control pipeline are fixed to the outer wall of the first insulated oil pipe through pipeline protectors, pass through the large oil pipe hanger and then pass through the oil production tree as a whole. The production packer hydraulic control pipeline and the cable of the inverted electric submersible pump are fixed to the outer wall of the small oil pipe through pipeline protectors, pass through the small oil pipe hanger and then pass through the oil production tree as a whole.

9. A method for realizing a heavy oil injection and production integrated system by using a small oil pipe and electric pump as claimed in any one of claims 1 to 8, characterized in that: include: S1: Open the deep well safety valve and the bleed valve, set the high-temperature packer, inject hot fluid into the well using the heat injection string, and inject gas using the heat injection string and the casing annulus. When injecting hot fluid, the hot fluid passes through the first insulated oil pipe, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation; when injecting gas, the gas passes through the Christmas tree wing valve, the first insulated oil pipe and the casing annulus, the bleed valve, the first insulated oil pipe and the casing annulus, the perforated pipe, the second insulated oil pipe, the deep well safety valve, and the second insulated oil pipe to the formation. After the heat injection is completed, the well enters the soaking and blowing stages in sequence. During the blowing stage, the formation fluid flows out to the wellhead through the heat injection string. S2: After the blowout is completed, the inverted pump is put into the first insulated tubing through the small tubing, the upper production packer and the lower production packer are set, the pump is started, and the produced fluid is lifted to the wellhead. The formation produced fluid passes through the formation, the second insulated tubing, the deep well safety valve, the second insulated tubing, the perforated pipe, the flow guide pipe, the centrifugal pump inlet, the centrifugal pump, the centrifugal pump outlet, the inverted electric submersible pump and the annulus of the first insulated tubing, and the electric submersible pump connector to the small tubing for output; S3: When the ESP production drops to the economic level, stop the pump, release the upper and lower production packers, and pull out the inverted pump unit through the small tubing. S4: Repeat step S1 again.

10. The method for realizing an integrated system for heavy oil injection and production by using a small oil pipe to cast and retrieve an electric pump according to claim 9, characterized in that: When the inverted pump unit is put in and out through a small oil pipe, the workover rig is used to complete the pipe string movement operation.

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