CN118309394A - Lifting pipe column for petroleum exploitation - Google Patents

Abstract

The invention relates to a lifting pipe column for petroleum exploitation, which comprises an underground double-screw rotor pump, wherein a liquid outlet at the upper end of the underground double-screw rotor pump is connected with a first oil pipe; the motor protector is used for supplying motor oil to the submersible motor and balancing the pressure difference between the motor oil and well liquid; the upper end of the first oil pipe is connected with a safety valve, the upper end of the safety valve is connected with a second oil pipe, the second oil pipe is connected with a wellhead Christmas tree, and the safety valve is connected with a hydraulic control pipeline. The invention adopts the submersible motor to drive the underground double-screw rotor pump, has the advantages of high pump efficiency and easy maintenance, and can be used for exploiting thick oil with wider viscosity range; the invention is suitable for large inclined wells or horizontal wells.

Description

Lifting pipe column for petroleum exploitation

Technical Field

The invention belongs to the technical field of petroleum lifting, and particularly relates to a lifting pipe column for petroleum exploitation.

Background

The thick oil is an important component of petroleum resources in China, and accounts for about 20% of the total land petroleum resources and 70% of the total offshore petroleum resources, and can be divided into: common thickened oil, extra thickened oil and super thickened oil (natural asphalt). Because the thick oil has the characteristics of large viscosity, poor fluidity and the like, the conventional process cannot meet the exploitation requirements. At present, aiming at the exploitation of extra and ultra-thick oil, a steam throughput injection and exploitation process technology and a steam assisted gravity drainage technology (SAGD) are mainly adopted, and the two technologies depend on high-temperature steam to heat thick oil in a stratum, so that the thick oil buried in the stratum has lower viscosity and higher fluidity, and meanwhile, the exploitation of the extra and ultra-thick oil is realized by means of different artificial lifting modes. For common thick oil with certain fluidity, the thick oil is usually produced by directly putting an electric submersible pump, a single-screw pump, an oil pumping unit and the like into the thick oil according to well condition conditions.

The artificial lifting technology commonly used for exploitation of extra-heavy oil and ultra-heavy oil in offshore oil fields at present mainly comprises the following steps: jet pump injection and production integrated technology, high-temperature electric pump injection and production integrated technology and two-pass tubular column electric pump exploitation technology; the jet pump needs to be provided with a ground power fluid pressurizing system and a water treatment system, so that the problem of large occupied area exists, and the application range of the jet pump is limited by pump efficiency and discharge capacity; the electric submersible pump has the characteristics of small occupied area, low maintenance cost and the like, but in the middle and later stages of thickened oil thermal recovery, the viscosity of thickened oil rises quickly (the viscosity is very sensitive to the temperature) along with the gradual reduction of the stratum temperature, and the problems of overload (high viscosity or emulsification), low pump efficiency and the like exist; meanwhile, the high-gas-content well can cause underload or airlock of the electric pump, and the next injection and production conversion needs to be carried out in advance, so that the economical efficiency in the whole thermal production period is further reduced.

The artificial lifting technology for thermal recovery of extra and ultra thick oil in land oil fields mainly comprises the following steps: injection and production integrated lifting technology of an oil pump, lifting technology of a ground-driven all-metal single-screw pump and the like; wherein, the all-metal single-screw pump and the oil pump are only suitable for the working conditions of small discharge capacity, low lift and lower sand content.

Aiming at common thickened oil exploitation, the method mainly comprises the following steps: the limitations of the underground single screw pump, the submersible electric pump, the oil pump and the like mainly comprise small discharge capacity, poor well inclination adaptability and the like.

In summary, the lifting technology for the thick oil exploitation field in the current market has a certain limitation.

Disclosure of Invention

In order to solve all or part of the problems, the invention aims to provide a lifting pipe column for petroleum exploitation, which adopts a submersible motor to drive a downhole double-screw rotor pump, and the double-screw rotor pump has the advantages of high pump efficiency and large volumetric efficiency.

According to one aspect of the invention, there is provided a lifting string for oil exploitation, comprising a downhole twin screw rotor pump, a first oil pipe is connected to a liquid outlet at the upper end of the downhole twin screw rotor pump, the downhole twin screw rotor pump is used for pumping a well into the first oil pipe, the downhole twin screw rotor pump is connected with an oil submersible motor, and the oil submersible motor is connected with a wellhead power supply.

Further, the motor protector is further arranged, the upper end of the motor protector is connected with a liquid inlet of the underground double-screw rotor pump, the lower end of the motor protector is connected with the submersible motor, and the motor protector is used for supplying motor oil for the submersible motor and balancing the pressure difference between the motor oil and well liquid.

Further, the upper end of the first oil pipe is connected with a safety valve, the upper end of the safety valve is connected with a second oil pipe, the second oil pipe is connected with a wellhead Christmas tree, and the safety valve is connected with a hydraulic control pipeline.

Further, the device also comprises a production packer, wherein the production packer is used for sealing an annulus between the first oil pipe and the casing, and a hydraulic control pipeline is connected to the production packer.

Further, the pipe column system is used as a production pipe column of a steam-assisted gravity drainage oil extraction process.

Further, the pipe column system is used for a thin oil exploitation or thick oil cold exploitation process.

Further, the device further comprises a Y joint, wherein an upper channel of the Y joint is connected with the first oil pipe, a production channel of the Y joint is connected with a liquid outlet of the underground double-screw rotor pump, a heat injection channel of the Y joint is connected with the third oil pipe, and the Y joint realizes the switching of the communication between the production channel and the upper channel and the communication between the heat injection channel and the upper channel through the control of a hydraulic control pipeline.

Further, the first oil pipe, the second oil pipe and the second oil pipe are all heat insulation oil pipes.

Furthermore, the tubular column system is used for a steam huff and puff injection and production integrated oil extraction process.

Further, the submersible motor is connected with the wellhead power supply through a cable.

According to the technical scheme, the lifting pipe column for petroleum exploitation has the following beneficial effects:

The lifting pipe column adopts the submersible motor to drive the underground double-screw rotor pump, and the double-screw rotor pump has the advantages of high pump efficiency, high volumetric efficiency, simple structure, safety, controllability, small occupied area and easiness in maintenance, can be suitable for the exploitation of thick oil with a wider viscosity range, and can also be used for the exploitation of a high-gas-content well;

the lifting pipe column of the invention can be suitable for exploiting various thin oil or thick oil on the sea and on the land; because the lifting pipe column has a short and compact structure, the lifting pipe column disclosed by the invention can be suitable for exploitation of a large inclined well or a horizontal well;

The lifting pipe column can be used for a steam huff-puff injection and production integrated oil extraction process, can be used as a production pipe column of an SAGD oil extraction process, and can also be used for a thick oil cold extraction oil extraction process.

Drawings

FIG. 1 is a schematic illustration of a lifting string according to one embodiment of the present invention;

FIG. 2 is a schematic view of a lifting string according to another embodiment of the present invention;

The reference numerals in the drawings are: the well head christmas tree 1, second oil pipe 2, relief valve 3, production packer 4, first oil pipe 5, double screw rotor pump 6 in pit, motor protector 7, submersible motor 8, cable 9, hydraulically controlled pipeline 10, Y joint 11, third oil pipe 12.

Detailed Description

For a better understanding of the objects, structures and functions of the present invention, a lifting string for oil production according to the present invention will be described in further detail with reference to the accompanying drawings.

1-2, A lifting pipe column for petroleum exploitation according to an embodiment of the present invention is shown, including a downhole twin-screw rotor pump 6, a liquid outlet at an upper end of the downhole twin-screw rotor pump 6 is connected with a first oil pipe 5, the downhole twin-screw rotor pump 6 is used for pumping a well into the first oil pipe 5, the downhole twin-screw rotor pump 6 is connected with a submersible motor 8, and the submersible motor 8 is connected with a wellhead power source.

Specifically, the lifting pipe column of the embodiment comprises an underground double-screw rotor pump 6 and an oil-submersible motor 8, when in production, the oil-submersible motor 8 can drive the underground double-screw rotor pump 6 to work by supplying power to the oil-submersible motor 8, the underground double-screw rotor pump 6 works to pump the well fluid in the well into the first oil pipe 5, and then the well fluid can be lifted to the ground through the first oil pipe 5, so that smooth well fluid exploitation is realized.

The lifting pipe column provided by the embodiment of the invention adopts the submersible motor 8 to drive the underground double-screw rotor pump 6, and the double-screw rotor pump has the advantages of high pump efficiency, high volumetric efficiency, simple structure, safety, controllability, small occupied area and easiness in maintenance, and can be suitable for exploiting thick oil with a wider viscosity range; the lifting pipe column of the embodiment of the invention can be suitable for the exploitation of various thin oil or thick oil on the sea and on the land, and can also be used for the exploitation of high-gas-content wells; because the underground double-screw rotor pump in the lifting pipe column has a short and compact structure, the lifting pipe column can be suitable for exploitation of a large inclined well or a horizontal well.

In the concrete implementation, the underground double-screw rotor pump 6 runs directly with the submersible motor 8 through a transmission system, and a driving shaft, a driven shaft and a spiral sleeve of the underground double-screw rotor pump 6 can adopt a split structure or an integrated structure; the whole layout of the underground double-screw rotor pump 6 can adopt various schemes such as single suction, double suction, mixed type and the like by combining the well condition requirement; the number of screw poles of the underground double-screw rotor pump 6 can also adopt a plurality of lead and multistage series connection combination modes according to the requirements of lift and displacement. The downhole twin screw rotor pump 6 and the first oil pipe 5 can be connected by adopting a sealing thread buckle.

The submersible motor 8 consists of a stator and a rotor and is used for providing power for the underground double-screw rotor pump 6. In specific implementation, the submersible motor 8 can be selected from a low-temperature (less than or equal to 180 ℃) motor, a medium-temperature (180-250 ℃) motor or a high-temperature (250-370 ℃) motor according to the use temperature.

In an embodiment, the motor protector 7 is further included, the upper end of the motor protector 7 is connected with the liquid inlet of the underground double-screw rotor pump 6, the lower end of the motor protector 7 is connected with the submersible motor 8, and the motor protector 7 is used for supplying motor oil for the submersible motor 8 and balancing the pressure difference between the motor oil and well liquid.

The embodiment also comprises a motor protector 7, wherein the motor protector 7 has two functions, one function is to provide motor oil for the inside of the submersible motor 8, ensure the lubrication of the submersible motor 8 and avoid the damage of the submersible motor 8 caused by dry grinding; the other function is to isolate the motor oil from the well fluid, prevent the well fluid from entering the motor to burn down the submersible motor 8 and balance the pressure between the motor oil inside the submersible motor 8 and the well fluid outside the submersible motor 8.

The motor protector 7 of this embodiment is disposed between the downhole twin screw rotor pump 6 and the submersible motor 8, and the motor protector 7 and the downhole twin screw rotor pump 6, the motor protector 7 and the submersible motor 8 may be connected by a sealing screw thread. In specific implementation, for example, a split motor protector 7 including an upper protector and a lower protector is adopted, the upper protector is mainly used for preventing well fluid from entering the motor and balancing the pressure between the motor oil inside the submersible motor 8 and the well fluid outside the submersible motor 8, and the lower protector is used for supplying the motor oil to the submersible motor 8.

In an embodiment, the upper end of the first oil pipe 5 is connected with a safety valve 3, the upper end of the safety valve 3 is connected with a second oil pipe 2, the second oil pipe 2 is connected with the wellhead production tree 1, and the safety valve 3 is connected with a hydraulic control pipeline 10.

The relief valve 3 of the present embodiment is used to prevent high pressure fluid downhole from overflowing through the annulus passage to the wellhead. In this embodiment, the switching of the open and close states of the safety valve 3 is realized by a pilot operated line 10.

In the concrete implementation, the first oil pipe 5 and the safety valve 3, the safety valve 3 and the second oil pipe 2 and the wellhead christmas tree 1 can be connected by adopting a sealing thread. The first oil pipe 5 and the second oil pipe 2 can be selected from various specifications such as 4-1/2 ', 3-1/2 ', 2-7/8 ', and the like.

The wellhead production tree 1 mainly comprises a flank valve, an oil pipe four-way joint, a hanger, a tree body and the like, the wellhead production tree 1 is a wellhead control device capable of realizing open flow of well liquid and production of liquid production, and the structure of the wellhead production tree 1 can be designed in various combinations according to different requirements of thick oil exploitation process schemes.

The hydraulic control pipeline 10 is made of stainless steel, the pressure resistance is more than or equal to 30Mpa, the temperature resistance is more than or equal to 350 ℃, and the hydraulic control pipeline 10 is used for controlling the functions of opening, closing, setting and the like of the safety valve 3, the production packer 4 and other underground tools so as to realize intelligent control of the underground tools.

In an embodiment, the production packer 4 is further comprised, the production packer 4 is used for sealing an annulus between the first tubing 5 and the casing, and the production packer 4 is connected with a pilot line 10.

The production packer 4 of the present embodiment is mainly used for ensuring the safety of the wellbore process and preventing the high-pressure fluid at the bottom of the well from overflowing to the wellhead through the annular channel.

In one embodiment, submersible motor 8 is connected to a wellhead power source via cable 9. The cable 9 is a high temperature cable or a normal cable as required.

When the oil extraction system is specifically applied, the pipe column system comprising the wellhead production tree 1, the second oil pipe 2, the safety valve 3, the first oil pipe 5, the underground double-screw rotor pump 6, the motor protector 7 and the submersible motor 8 can be used as a production pipe column of a steam-assisted gravity drainage oil extraction process (SAGD process), can be used for a thin oil exploitation or thick oil cold exploitation process, and can also be used for a steam huff-puff injection and extraction integrated oil extraction process; the temperature and pressure resistance requirements for each component are different when used in different processes. Specific:

The production packer 4 can be divided into a high-temperature type production packer and a general type production packer, wherein the integral temperature resistance of the high-temperature type production packer is more than or equal to 350 ℃, and the pressure resistance is more than or equal to 15Mpa; the integral temperature resistance of the general production packer is more than or equal to 180 ℃, and the pressure resistance is more than or equal to 15Mpa; the safety valve 3 can be divided into a high temperature type (temperature resistant 350 ℃) and a common type (temperature resistant 180 ℃), and the pressure resistance of the two safety valves 3 is more than or equal to 15Mpa; the first oil pipe 5 and the second oil pipe 2 are divided into a heat insulation oil pipe or a common oil pipe; the submersible motor 8 comprises a low-temperature (less than or equal to 180 ℃) motor, a medium-temperature (180 ℃ to 250 ℃) motor or a high-temperature (250 ℃ to 370 ℃) motor according to the use temperature; the underground double-screw rotor pump 6 comprises two types of heat resistance which is more than or equal to 350 ℃, pressure resistance which is more than or equal to 21Mpa, heat resistance which is less than or equal to 180 ℃ and pressure resistance which is more than or equal to 21 Mpa; the wellhead production tree 1 comprises a normal temperature wellhead production tree and a high temperature wellhead production tree; in the concrete implementation, the oil extraction process corresponding to the pipe column system is reasonably selected.

In one embodiment, as shown in fig. 1, when a tubular column system comprising a wellhead christmas tree 1, a second oil pipe 2, a safety valve 3, a first oil pipe 5, a downhole double-screw rotor pump 6, a motor protector 7 and a submersible motor 8 is used for thick oil cold recovery and thin oil recovery, a common production packer with a temperature resistance of not less than 180 ℃ and a pressure resistance of not less than 15Mpa is used; a common safety valve with the temperature resistance of 180 ℃ and the pressure resistance of more than or equal to 15Mpa is used; the submersible motor 8 is a low-temperature (less than or equal to 180 ℃) motor, a medium-temperature (250-180 ℃) motor or a high-temperature (250-370 ℃) motor; the motor protector 7 adopts a common motor protector.

Aiming at the thin oil exploitation and thick oil cold exploitation processes, the pipe column system can realize large-displacement and high-efficiency production.

The specific steps of the pipe column system used for thin oil exploitation and thick oil cold exploitation in the embodiment are as follows: before formal production, the ground hydraulic control system opens the common safety valve through the hydraulic control pipeline 10 to ensure that the production pipe column is smooth, and the wellhead power supply is transmitted to the common submersible motor through the cable 9 by starting the pump ground control cabinet, and the common submersible motor drives the underground double-screw rotor pump 6 to start pumping well fluid; in the formal production stage, the produced fluid enters the production flow through the first oil pipe 5, the safety valve 3, the second oil pipe 2 and the wellhead Christmas tree 1, so that thick oil cold recovery lifting or thin oil lifting is realized.

In another embodiment, as shown in fig. 1, when a tubular column system comprising a wellhead christmas tree 1, a second oil pipe 2, a safety valve 3, a first oil pipe 5, an underground double-screw rotor pump 6, a motor protector 7 and a submersible motor 8 is used as a production tubular column of a steam-assisted gravity drainage oil extraction process (SAGD process), all parts such as a core part shell, a main screw shaft, a slave screw shaft, a sealing part and the like of the underground double-screw rotor pump 6 are all of all-metal design, and the overall temperature resistance is more than or equal to 350 ℃, and the pressure resistance is more than or equal to 21Mpa; the submersible motor 8 is a high-temperature (250-370 ℃) motor; the safety valve 3 adopts a high-temperature safety valve with the temperature resistance of 350 ℃ and the pressure resistance of more than or equal to 15 Mpa; the motor protector 7 adopts a high-temperature motor protector; the first oil pipe 5 and the second oil pipe 2 are common oil pipes.

The SAGD process comprises two layers of pipe columns in specific oil extraction, an upper heat injection pipe column and a lower production pipe column, the pipe column system of the embodiment is used as the production pipe column of the SAGD process, and oil extraction performed by adopting the pipe column of the embodiment can not influence the normal operation of heat injection, so that the SAGD process can achieve the aim of maintaining production while injecting heat, and can furthest improve the production efficiency.

The specific steps of the pipe column system of the embodiment for oil extraction as a production pipe column of an SAGD process are as follows: before formal production, the ground hydraulic control system opens the high-temperature safety valve through the hydraulic control pipeline 10 to ensure smooth production pipe columns, and the wellhead power supply is transmitted to the high-temperature submersible motor through the high-temperature cable by starting the pump ground control cabinet, so that the submersible motor 8 drives the high-temperature downhole double-screw rotor pump to start and formally enter the production stage at the moment; the produced well fluid enters the production flow through the common first oil pipe 5, the high-temperature safety valve, the common second oil pipe 2 and the high-temperature wellhead Christmas tree, so that thick oil thermal recovery lifting is realized.

In a third embodiment, as shown in fig. 2, the pipe column system is used in a steam huff-puff injection and production integrated oil extraction process, and at this time, the pipe column system further comprises a Y joint 11, wherein an upper channel of the Y joint 11 is connected with the first oil pipe 5, a production channel of the Y joint 11 is connected with a liquid outlet of the downhole twin-screw rotor pump 6, a heat injection channel of the Y joint 11 is connected with the third oil pipe 12, and the Y joint 11 is controlled by a hydraulic control pipeline 10 to realize the switching of the communication between the production channel and the upper channel and the communication between the heat injection channel and the upper channel.

The Y joint 11 of the embodiment is provided with an upper channel, the upper channel is connected with the first oil pipe through a sealing thread buckle, the Y joint 11 is provided with two lower channels which are a production channel and a heat injection channel respectively, the heat injection channel is connected with a third oil pipe below the production channel, and the production channel is connected with a liquid outlet of the underground double-screw rotor pump 6 below the production channel; the upper channel of the Y joint can be communicated with the heat injection channel, and the production channel is in a closed state after the upper channel is communicated with the heat injection channel, so that the Y joint can be used for injecting heat downwards through a wellhead and can also be used for self-injection of well fluid upwards; the upper channel of the Y joint can be communicated with the production channel, and the heat injection channel is in a closed state after the upper channel is communicated with the production channel, so that the Y joint can be used for well fluid production through an oil-submerged motor and an underground double-screw rotor pump; the production channel is communicated with the upper channel or the heat injection channel is communicated with the upper channel through hydraulic control pipeline control, for example, the heat injection channel is communicated with the upper channel through pressurizing of the hydraulic control pipeline 10, the production channel is closed, the production channel is communicated with the upper channel through pressure relief of the hydraulic control pipeline 10, and the heat injection channel is closed.

In the embodiment, the Y joint 11 adopts an all-metal design, the integral temperature resistance is more than or equal to 350 ℃, the pressure resistance is more than or equal to 15Mpa, the conversion between a heat injection channel and a production channel is mainly realized in the steam throughput injection and production integrated technology, the heat injection channel is opened through the hydraulic control pipeline 10 when steam is injected and the steam is discharged, the production channel is closed, and at the moment, the heat injection channel is communicated with an upper channel, so that high-temperature steam is rapidly injected into a well through the upper channel and the heat injection channel; after the waiting for the end of the braising well, the open flow is realized through the channel; during production, the production channel is communicated with the upper channel through the hydraulic control pipeline 10, and at the moment, normal production of oil extraction can be realized through the underground double-screw rotor pump 6.

When the pipe column system is used for the steam huff-puff injection-production integrated oil extraction process, the core component shell, the main screw shaft, the auxiliary screw shaft, the sealing component and other components of the underground double-screw rotor pump 6 are all designed by adopting all metals, and the integral temperature resistance is more than or equal to 350 ℃, and the pressure resistance is more than or equal to 21Mpa; the submersible motor 8 is a high-temperature (250-370 ℃) motor; the safety valve 3 adopts a high-temperature safety valve with the temperature resistance of 350 ℃ and the pressure resistance of more than or equal to 15 Mpa; the motor protector 7 adopts a high-temperature motor protector; the first oil pipe 5, the second oil pipe 2 and the third oil pipe 12 are all heat-insulating oil pipes.

The embodiment adopts one pipe column to realize the integrated operation of heat injection, open flow and production. Specifically, the heat injection stage: the ground hydraulic control system opens the high-temperature safety valve through the hydraulic control pipeline 10, simultaneously opens the heat injection channel of the Y joint 11 to the bottom of the well, closes the production channel of the underground double-screw rotor pump 6, and at the moment, high-temperature and high-pressure steam is injected into the bottom of the well through the high-temperature wellhead christmas tree, the second oil pipe 2, the high-temperature safety valve, the first oil pipe 5, the Y joint 11 and the third oil pipe 12, so as to heat extra-thick in the stratum. After the steam injection is finished, the steam injection is carried out through short-term well-stewed operation and then is switched into an open-flow stage. And (3) a blowout stage: the high-temperature fluid in the ground layer is sprayed upwards through the third oil pipe 12, the Y joint 11, the first oil pipe 5, the high-temperature safety valve, the second oil pipe 2 and the high-temperature wellhead Christmas tree. The production stage comprises the following steps: when the open flow is finished, the production stage is started to be shifted into, the ground hydraulic control system opens the production channel of the Y joint 11 through the hydraulic control pipeline 10, simultaneously closes the heat injection channel leading to the bottom of the well, and the wellhead power supply is transmitted to the high-temperature submersible motor through the high-temperature cable by starting the pump ground control cabinet, the submersible motor 8 drives the high-temperature downhole double-screw rotor pump to start and formally enter the production stage at the moment, and produced well fluid enters the production flow through the Y joint 11, the first oil pipe 5, the high-temperature safety valve, the second oil pipe 2 and the high-temperature wellhead christmas tree, so that thick oil thermal recovery lifting is realized.

In the above embodiment, the submersible motor 8 is used as a power source of the downhole twin screw rotor pump 6, not only limited to a three-phase asynchronous motor, but also a permanent magnet motor, a direct current motor and the like can be selected; the lifting pipe column of the embodiment of the invention comprises a plurality of underground tools, wherein a safety valve 3, a production packer 4 and the like can be selected according to the actual thick oil thermal recovery and cold recovery process requirements, and are not compulsorily configured; the lifting pipe column provided by the embodiment of the invention focuses on the field of thick oil lifting, and can be selected for special working conditions such as high-gas-content oil wells and conventional thin oil exploitation.

Again, the description: the lifting pipe column of the embodiment of the invention can be suitable for exploiting various thin oil and thick oil on the sea and on the land, and can be suitable for producing large-well inclined wells and horizontal wells due to the short and compact structure; aiming at the steam huff-puff injection and production process, the safe and reliable operation under three working conditions of heat injection, open-flow injection and production can be met, and the conversion period of heat injection and production can be prolonged; aiming at a steam assisted gravity drainage process (SAGD), the oil extraction can be realized while steam is injected, and the production efficiency is improved to the maximum extent; aiming at the thin oil and thick oil cold recovery process, the system can realize large-discharge and high-efficiency production.

It is noted that unless otherwise indicated, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs.

In the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention, and are intended to be included within the scope of the appended claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims (10)

1. The lifting pipe column for oil exploitation is characterized by comprising an underground double-screw rotor pump, wherein a liquid outlet at the upper end of the underground double-screw rotor pump is connected with a first oil pipe, the underground double-screw rotor pump is used for pumping a well liquid into the first oil pipe, the underground double-screw rotor pump is connected with an oil submersible motor, and the oil submersible motor is connected with a wellhead power supply.

2. A lifting string for oil extraction according to claim 1, further comprising a motor protector, an upper end of the motor protector being connected to a fluid inlet of the downhole twin screw rotor pump, a lower end of the motor protector being connected to the submersible motor, the motor protector being adapted to supply the submersible motor with motor oil and to balance a pressure differential between the motor oil and well fluid.

3. The lifting string for oil exploitation according to claim 1, wherein the upper end of the first oil pipe is connected with a safety valve, the upper end of the safety valve is connected with a second oil pipe, the second oil pipe is connected with a wellhead christmas tree, and the safety valve is connected with a hydraulic control pipeline.

4. A lifting string for oil extraction according to claim 3, further comprising a production packer for sealing an annulus between the first tubing and casing, the production packer being connected to a pilot line.

5. A lifting string for oil extraction according to claim 4, wherein the string system is for use as a production string for a steam assisted gravity drainage oil extraction process.

6. A lifting string for oil extraction according to claim 4, wherein the string system is used in a thin oil extraction or thick oil cold extraction process.

7. The lifting string for oil exploitation according to claim 4, further comprising a Y joint, wherein an upper channel of the Y joint is connected with the first oil pipe, a production channel of the Y joint is connected with a liquid outlet of the downhole twin screw rotor pump, a heat injection channel of the Y joint is connected with a third oil pipe, and the Y joint is controlled by a hydraulic control pipeline to realize the communication between the production channel and the upper channel and the switching between the heat injection channel and the upper channel.

8. The lift string for oil production of claim 7, wherein the first oil pipe, the second oil pipe, and the second oil pipe are each insulated oil pipes.

9. The lifting string for oil recovery according to claim 7, wherein the string system is used in a steam huff and puff injection and production integrated oil recovery process.

10. A lifting string for oil extraction according to any of claims 1-9, wherein the submersible motor is connected to the wellhead power source by means of a cable.