CN108119100B - Oil well lifting system and oil pumping method thereof - Google Patents

Oil well lifting system and oil pumping method thereof Download PDF

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Publication number
CN108119100B
CN108119100B CN201611078579.9A CN201611078579A CN108119100B CN 108119100 B CN108119100 B CN 108119100B CN 201611078579 A CN201611078579 A CN 201611078579A CN 108119100 B CN108119100 B CN 108119100B
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liquid
assembly
oil
power
oil pipe
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CN108119100A (en
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李志广
李川
闫永维
张子佳
李风涛
甘宝安
陈冬
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Petrochina Co Ltd
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Petrochina Co Ltd
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    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/12Methods or apparatus for controlling the flow of the obtained fluid to or in wells
    • E21B43/121Lifting well fluids
    • E21B43/129Adaptations of down-hole pump systems powered by fluid supplied from outside the borehole
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/34Arrangements for separating materials produced by the well
    • E21B43/38Arrangements for separating materials produced by the well in the well

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

The invention discloses an oil well lifting system and an oil pumping method thereof, and belongs to the technical field of underground oil extraction. The well lifting system comprises: the oil pipe assembly comprises a first oil pipe string and a second oil pipe string. The embodiment of the invention avoids the problems of temperature rise, burnout, cable breakdown and the like of the electric submersible pump caused by the fact that the flow rate of the production liquid cannot reach the cooling flow rate of the shell of the electric submersible pump when the electric submersible pump lifting system is used in a high-inclination low-liquid-supply oil well; the problem that a special power liquid station is required to be arranged when a hydraulic drive lifting system is used is solved, and the problems that the hydraulic drive screw oil extraction device is strong in dependence on ground water and the power liquid station and limited in use condition are solved; the problem of because power liquid and production fluid motion direction before mixing are opposite, when the proportion of power liquid in the mixed solution is great, restrain the output of production fluid is solved, the efficiency of lifting has been improved.

Description

Oil well lifting system and oil pumping method thereof
Technical Field
The invention relates to the technical field of underground oil extraction, in particular to an oil well lifting system and an oil pumping method thereof.
Background
The highly deviated oil well generally means an oil well having an angle of inclination of 45 to 85 degrees between the oil well and the vertical direction, and the highly deviated oil well has been increasing year by year as the development of oil fields continues. During the exploitation process of the high-inclination oil well, production fluid in the high-inclination oil well needs to be pumped to the ground through an oil well lifting system, wherein the production fluid refers to fluid produced in the high-inclination oil well and mainly comprises crude oil and underground water.
At present, a common oil well lifting system comprises an electric submersible pump lifting system and a hydraulic drive lifting system, wherein the electric submersible pump lifting system is matched with an electric submersible pump, and during oil pumping, production liquid flows through a motor shell in the electric submersible pump to cool the motor. The hydraulically driven lifting system may also be referred to as a hydraulically driven screw oil recovery device, as shown in fig. 1, comprising: the oil pump comprises a casing 01, an oil pipe 02, a hydraulic motor 03, a transmission part 04 and a screw pump 05, wherein the oil pipe 02 is positioned inside the casing 01, an oil casing annulus is formed between the casing 01 and the oil pipe 02, the hydraulic motor 03 and the screw pump 05 are positioned inside the oil pipe 02, one end of the transmission part 04 is connected with the hydraulic motor 03, the other end of the transmission part 04 is connected with the screw pump 05, and radial liquid passing holes are formed in the oil pipe 02 and in positions corresponding to the transmission part 04. In order to power the hydraulic drive screw oil extraction device, a power fluid station is usually arranged on the ground, surface water is pressurized and then injected into the oil pipe 02 as power fluid to be mixed with the production fluid delivered by the screw pump 05 when the power fluid is delivered to the position of the transmission part 04 through the hydraulic motor 03, so as to obtain mixed fluid, and the mixed fluid is delivered to the oil jacket annulus through radial liquid passing holes in the position, corresponding to the transmission part 04, on the oil pipe 02 and then delivered to the ground through the oil jacket annulus.
In the process of implementing the invention, the inventor finds that the prior art has at least the following problems:
when the electric submersible pump lifting system is used, in the oil pumping process of a large-inclination low-liquid-volume oil well, the flow rate of production liquid cannot reach the cooling flow rate of a motor shell due to low liquid production volume of the oil well, so that the problems of motor temperature rise, motor burnout, cable breakdown and the like can be caused. When the hydraulic drive lifting system is used, a special power liquid station is required to be arranged, and the power liquid station needs to pressurize surface water to be used as power liquid to drive the hydraulic drive screw oil extraction device to work, so that the hydraulic drive screw oil extraction device has strong dependence on the surface water and the power liquid station, the use condition is limited, and in addition, the motion directions of the power liquid and the production liquid before mixing are opposite, so when the proportion of the power liquid in the mixed liquid is large, the output of the production liquid is inhibited, and the lifting efficiency is influenced.
Disclosure of Invention
In order to solve the problems in the prior art, the embodiment of the invention provides an oil well lifting system and an oil pumping method thereof. The technical scheme is as follows:
in one aspect, there is provided a well lifting system comprising: the device comprises a power fluid circulation assembly, a wellhead mechanism assembly, a sleeve, an oil pipe assembly, a screw motor assembly, a transmission assembly and a screw pump, wherein the oil pipe assembly comprises a first oil pipe string and a second oil pipe string;
the power fluid circulation assembly is connected with the wellhead mechanism assembly, the wellhead mechanism assembly is respectively connected with the casing pipe and the first oil pipe string which are positioned in an oil well, the first oil pipe string, the screw motor assembly, the transmission assembly, the screw pump and the second oil pipe string are sequentially connected, the first oil pipe string, the screw motor assembly, the transmission assembly, the screw pump and the second oil pipe string are positioned in the casing pipe, and an oil sleeve annulus is formed between the first oil pipe string, the screw motor assembly, the transmission assembly, the screw pump and the second oil pipe string and the casing pipe;
the power fluid circulation assembly is used for injecting power fluid into the transmission assembly through the oil sleeve annulus through the wellhead mechanism assembly, the screw motor assembly conveys the power fluid into an oil pipe cavity under the action of the power fluid and drives the transmission assembly to rotate, the transmission assembly drives the screw pump under the driving of the screw motor assembly, production fluid in the oil well is conveyed into the oil pipe cavity through the screw motor assembly by the screw pump so as to be mixed with the power fluid, mixed liquid is obtained, and the oil pipe cavity is a cavity formed among the first oil pipe string, the screw motor assembly and the wellhead mechanism assembly;
after the mixed liquid is conveyed to the power liquid circulation assembly through the oil pipe chamber, the power liquid circulation assembly is further used for separating liquid from the mixed liquid and recycling the separated liquid as the power liquid.
Optionally, the wellhead mechanism assembly includes: the well head mechanism comprises a well head mechanism main body, a first oil pipe gate, a second oil pipe gate and a casing pipe gate;
the wellhead mechanism main body is respectively connected with the casing and the first oil pipe string, the first oil pipe gate and the second oil pipe gate are respectively communicated with the oil pipe assembly through the wellhead mechanism main body, and the casing gate is communicated with the oil sleeve annulus through the wellhead mechanism main body.
Optionally, the oil pipe assembly further comprises: the packer and the anti-rotation anchoring mechanism;
the packer and the anti-rotation anchoring mechanism are respectively connected with the second oil pipe string, the packer is located above the anti-rotation anchoring mechanism, and the anti-rotation anchoring mechanism is close to the bottom end of the second oil pipe string.
Optionally, the screw motor assembly includes: a motor stator and a motor rotor;
the top end of the motor stator is connected with the first oil pipe string, the bottom end of the motor stator is connected with the transmission assembly, the motor rotor is located inside the motor stator, an axial liquid passing channel is arranged inside the motor rotor, and the bottom end of the motor rotor is connected with the transmission assembly.
Optionally, the transmission assembly includes: the transmission assembly comprises a transmission assembly shell, a transmission shaft and a thrust bearing;
the top end of the transmission assembly shell is connected with a motor stator of the screw motor assembly, the bottom end of the transmission assembly shell is connected with the screw pump, and a first radial liquid passing hole is formed in the transmission assembly shell;
the top end of the transmission shaft is connected with a motor rotor included by the screw motor assembly, the bottom end of the transmission shaft is connected with the screw pump, a second radial liquid passing hole and a central hole liquid passing channel are arranged on the transmission shaft and communicated with the central hole liquid passing channel, and the thrust bearing is positioned above the second radial liquid passing hole so as to isolate the power liquid from the production liquid in the transmission assembly.
Optionally, the power fluid circulation assembly includes: the device comprises a gas-liquid separator, a desanding device, a liquid storage tank and a high-pressure plunger pump;
the liquid outlet of the liquid storage tank is connected with the liquid inlet of the high-pressure plunger pump, the liquid outlet of the high-pressure plunger pump is connected with the wellhead mechanism assembly, and power liquid in the liquid storage tank is conveyed into the oil sleeve annulus through the wellhead mechanism assembly after being pressurized by the high-pressure plunger pump;
the inlet of sand removal device with well head mechanism assembly connects, the liquid outlet of sand removal device with gas-liquid separator's inlet is connected, gas-liquid separator's liquid outlet with the inlet of liquid storage pot is connected, sand removal device is to passing through the mixed liquid that well head mechanism carried carries out the sand removal to carry the liquid after the sand removal extremely gas-liquid separator, gas-liquid separator separates out gas from the liquid after the sand removal, and regards as remaining liquid after will separating power liquid carry extremely in the liquid storage pot.
In another aspect, a method of pumping oil from an oil well lifting system is provided, the method comprising:
the power fluid circulation assembly injects power fluid into an oil casing annulus through the wellhead mechanism assembly, and the oil casing annulus is an annulus formed among the first tubing string, the screw motor assembly, the transmission assembly, the screw pump, the second tubing string and the casing;
under the action of power fluid in the oil sleeve annulus, the screw motor assembly conveys the power fluid into an oil pipe chamber and drives the transmission assembly to rotate, wherein the oil pipe chamber is a chamber formed among the first oil pipe string, the screw motor assembly and the wellhead mechanism assembly;
the transmission assembly is driven by the screw motor assembly to drive the screw pump to work;
in the working process of the screw pump, conveying production liquid in an oil well to the oil pipe chamber through the screw motor assembly so as to mix the power liquid with the production liquid to obtain mixed liquid, and conveying the mixed liquid to the ground and the power liquid circulation assembly;
and the power liquid circulation assembly separates liquid from the mixed liquid, and returns the separated liquid serving as power liquid to the step of injecting the power liquid into the oil sleeve annulus through the wellhead mechanism assembly.
Optionally, the power fluid circulation assembly includes: the device comprises a gas-liquid separator, a desanding device, a liquid storage tank and a high-pressure plunger pump;
the power fluid circulation assembly injects power fluid into the oil jacket annular space through the wellhead mechanism assembly, includes:
the high-pressure plunger pump sucks the power liquid from the liquid storage tank and pressurizes the power liquid;
and the high-pressure plunger pump injects the pressurized power fluid into the oil casing annulus through a casing gate of the wellhead mechanism at a specified displacement.
Optionally, the power fluid circulation assembly separates liquid from the mixed liquid, including:
the desanding device desalts the mixed liquor and conveys the desanded mixed liquor to the gas-liquid separator;
and the gas-liquid separator separates the liquid and the gas in the mixed liquid after sand removal and conveys the separated liquid into the liquid storage tank.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
the oil well lifting system is driven to work through hydraulic power, and the problems that when the electric submersible pump lifting system is used, in the oil pumping process of a large-inclination low-liquid-volume oil well, the temperature of a motor rises, the motor is burnt, cables are broken down and the like due to the fact that the liquid production volume of the oil well is low and the flow rate of the produced liquid cannot reach the cooling flow rate of a motor shell in the electric submersible pump are solved. The power liquid circulating assembly realizes the recycling of the power liquid, avoids the problem that a special power liquid station needs to be equipped when a hydraulic drive lifting system is used, and solves the problems that the hydraulic drive screw oil extraction device has strong dependence on ground water and the power liquid station and the use condition is limited. The screw motor assembly conveys power fluid into an oil pipe cavity under the action of the power fluid in the oil sleeve annulus, the transmission assembly drives the screw pump to work under the driving of the screw motor assembly, the screw pump conveys production fluid in an oil well into the oil pipe cavity through the screw motor assembly so as to mix the power fluid with the production fluid to obtain mixed fluid, and the mixed fluid is conveyed to the ground, wherein the oil pipe cavity is a cavity formed between the screw motor assembly and a wellhead mechanism assembly in the oil pipe assembly, so that the production fluid and the power fluid respectively enter the oil pipe cavity from the screw motor assembly before mixing, namely, the movement directions of the production fluid and the power fluid are the same before mixing. The problem of because power liquid and production fluid motion direction before mixing are opposite, when the proportion of power liquid in the mixed solution is great, can restrain the output of production fluid is solved, the efficiency of lifting has been improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a hydraulically driven screw oil recovery device provided in the prior art;
FIG. 2 is a schematic illustration of a first well lift system provided in accordance with an exemplary embodiment of the present invention;
FIG. 3 is a schematic illustration of a second well lift system provided in accordance with an exemplary embodiment of the present invention;
FIG. 4 is a schematic illustration of a transmission assembly provided in accordance with an exemplary embodiment of the present invention;
FIG. 5 is a schematic illustration of a power fluid circulation assembly provided in accordance with an exemplary embodiment of the present invention;
FIG. 6 is a schematic illustration of another power fluid circulation assembly provided in accordance with an exemplary embodiment of the present invention;
FIG. 7 is a flow chart of a method of pumping oil from a well lift system in accordance with an exemplary embodiment of the present invention;
FIG. 8 is a flow chart of another method of pumping oil from a well lift system in accordance with an exemplary embodiment of the present invention.
Reference numerals:
01: sleeve pipe, 02: oil pipe, 03: hydraulic motor, 04: transmission member, 05: a screw pump;
1: power liquid circulation assembly, 2: well head mechanism assembly, 3: sleeve pipe, 4: oil pipe assembly, 5: screw motor assembly, 6: transmission assembly, 7: a screw pump;
11: a liquid storage tank and 12: high-pressure plunger pump, 13: desanding device, 14: gas-liquid separator, 15: flow meter, 16: first pressure gauge, 17: reflux valve, 18: second pressure gauge, 19: electromagnetic valve, 10: a liquid level meter;
21: wellhead mechanism main body, 22: first pipe gate, 23: second pipe gate, 24: a casing gate;
41: first tubing string, 42: second tubing string, 43: packer, 44: anti-rotation anchoring mechanism, 45: screen, 46: plugging with a thread;
51: motor stator, 52: a motor rotor;
61: drive assembly housing, 62: transmission shaft, 63: a thrust bearing;
131: drag flask, 132: desander, 521: axial passage, 611: first radial liquid passing hole 621: second radial liquid passing hole, 622: the central hole is provided with a liquid passing channel.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 2 is a schematic diagram of a well lift system according to an exemplary embodiment of the present invention, as shown in fig. 2, comprising: the device comprises a power fluid circulation assembly 1, a wellhead mechanism assembly 2, a casing 3, an oil pipe assembly 4, a screw motor assembly 5, a transmission assembly 6 and a screw pump 7, wherein the oil pipe assembly 4 comprises a first oil pipe string 41 and a second oil pipe string 42;
the power fluid circulation assembly 1 is connected with the wellhead mechanism assembly 2, the wellhead mechanism assembly 2 is respectively connected with a casing 3 and a first tubing string 41 which are positioned in an oil well, the first tubing string 41, the screw motor assembly 5, the transmission assembly 6, the screw pump 7 and a second tubing string 42 are sequentially connected, the first tubing string 41, the screw motor assembly 5, the transmission assembly 6, the screw pump 7 and the second tubing string 42 are positioned in the casing 3, and an oil jacket annulus is formed between the first tubing string 41, the screw motor assembly 5, the transmission assembly 6, the screw pump 7 and the second tubing string 42 and the casing 3;
the power fluid circulation assembly 1 is used for injecting power fluid into the transmission assembly 6 through an oil sleeve annulus through the wellhead mechanism assembly 2, under the action of the power fluid, the screw motor assembly 5 conveys the power fluid into an oil pipe cavity and drives the transmission assembly 6 to rotate, the transmission assembly 6 is driven by the screw motor assembly 5 to drive the screw pump 7, production fluid in the oil well is conveyed into the oil pipe cavity through the screw motor assembly 5 by the screw pump 7 to be mixed with the power fluid to obtain mixed liquid, and the oil pipe cavity is a cavity formed among the first oil pipe string 41, the screw motor assembly 5 and the wellhead mechanism assembly 2;
after the mixed liquid is conveyed to the power fluid circulation assembly 1 through the oil pipe chamber, the power fluid circulation assembly 1 is also used for separating liquid from the mixed liquid and recycling the separated liquid as the power fluid.
In the embodiment of the invention, the oil well lifting system is driven to work through hydraulic power, so that the problems of motor temperature rise, motor burnout, cable breakdown and the like caused by the fact that the flow rate of production liquid cannot reach the cooling flow rate of a motor shell due to low liquid production volume of an oil well in the oil pumping process of a large-inclination low-liquid-volume oil well when the electric submersible pump lifting system is used are avoided. The power liquid circulating assembly realizes the recycling of the power liquid, avoids the problem that a special power liquid station needs to be equipped when a hydraulic drive lifting system is used, and solves the problems that the hydraulic drive screw oil extraction device has strong dependence on ground water and the power liquid station and the use condition is limited. The screw motor assembly conveys power fluid into an oil pipe cavity under the action of the power fluid in the oil sleeve annulus, the transmission assembly drives the screw pump to work under the driving of the screw motor assembly, the screw pump conveys production fluid in an oil well into the oil pipe cavity through the screw motor assembly so as to mix the power fluid with the production fluid to obtain mixed fluid, and the mixed fluid is conveyed to the ground, wherein the oil pipe cavity is a cavity formed between the screw motor assembly and a wellhead mechanism assembly in the oil pipe assembly, so that the production fluid and the power fluid respectively enter the oil pipe cavity from the screw motor assembly before mixing, namely, the movement directions of the production fluid and the power fluid are the same before mixing. The problem of because power liquid and production fluid motion direction before mixing are opposite, when the proportion of power liquid in the mixed solution is great, can restrain the output of production fluid is solved, the efficiency of lifting has been improved.
The connection mode of the sleeve 3 and the wellhead mechanism assembly 1 can be welding, bolt connection or extrusion type contact connection, and when the connection mode is bolt connection or extrusion type contact connection, a sealing gasket can be used between the contact surfaces of the sleeve 3 and the wellhead mechanism assembly 2 to ensure the connection tightness. The connection mode of the first tubing string and the wellhead mechanism assembly 2 can be threaded connection, welding or other connection modes. The first tubing string 41, the screw motor assembly 5, the transmission assembly 6, the screw pump 7 and the second tubing string 42 are connected in sequence, and the connection mode can be threaded connection or other connection modes.
It should be noted that, in actual production, the positions of the screw motor 5, the transmission assembly 6 and the screw pump 7 in the oil well are determined by the depth of the oil layer, and after the oil well lifting system is lowered into the oil well, it is necessary to ensure that the distance between the screw pump 7 and the oil layer is within a specified distance range, and the specified distance range is that when the distance between the screw pump 7 and the oil layer is within the specified distance range, oil pumping can be realized by the oil well lifting system.
Optionally, as shown in fig. 3, the wellhead mechanism assembly 2 includes: a wellhead mechanism body 21, a first tubing gate 22, a second tubing gate 23, and a casing gate 24;
the wellhead mechanism main body 21 is respectively connected with the casing 3 and the first tubing string 41, the first tubing gate 22 and the second tubing gate 23 are communicated with the first tubing string 41 through the wellhead mechanism main body 11, and the casing gate 24 is communicated with the oil casing annulus through the wellhead mechanism main body 31.
When the oil well lifting system works, the first oil pipe gate 22, the second oil pipe gate 23 and the casing pipe gate 24 are all in an open state, power fluid is injected into the oil ring air through the casing pipe gate 24, and the mixed liquid is conveyed to the ground through the first oil pipe gate 22 and the second oil pipe gate 23.
Optionally, as shown in fig. 2, the oil pipe assembly 4 further includes: a packer 43 and an anti-rotation anchoring mechanism 44;
the packer 43 and the anti-rotation anchoring mechanism 44 are respectively connected with the second tubing string 42, the packer 43 is positioned above the anti-rotation anchoring mechanism 44, and the anti-rotation anchoring mechanism 44 is close to the bottom end of the second tubing string 42;
wherein after the well lifting system is lowered into the well at a designated location, the packer 43 is set to separate the annulus of the oil jacket into two parts, with the motive fluid being located in the annulus above the annulus packer 43. At the same time, an anti-rotation anchoring mechanism 44 is anchored to prevent rotation of the second tubing string 42 in the casing 3.
It should be noted that the first tubing string 41 and the second tubing string 42 may be composed of a plurality of tubing pipes, and the plurality of tubing pipes may be connected by tubing joints.
For example, the packer 43 and the anti-rotation anchoring mechanism 44 may be connected to the second tubing string 42 by a threaded connection, although the packer 43 and the anti-rotation anchoring mechanism 44 may be connected to the second tubing string 42 by other connections.
Optionally, as shown in fig. 3, the oil pipe assembly 4 may further include: screen 45 and plug 46;
the sieve tube 45 is used for filtering production liquid and preventing impurities such as sand carried in the production liquid from entering the oil well lifting system, and the plug 46 is used for sealing the bottom of the sieve tube 45 so that the production liquid can enter the sieve tube 45 from sieve holes on the side of the sieve tube 45.
One end of the screen 45 is connected to the bottom end of the second tubing string 42 by a threaded connection or a welded connection, and the other end of the screen 45 is connected to the plug 46 by a threaded connection or a welded connection.
Alternatively, as shown in fig. 3, the screw motor assembly 5 includes: a motor stator 51 and a motor rotor 52; the top end of the motor stator 51 is connected with the first oil pipe string 41, the bottom end of the motor stator 51 is connected with the transmission assembly 6, the motor rotor 52 is located inside the motor stator 51, as shown in fig. 4, an axial liquid passing channel 521 is arranged inside the motor rotor 52, and the bottom end of the motor rotor 52 is connected with the transmission assembly 6.
The power fluid enters between the motor stator 51 and the motor rotor 52 through a gap between the transmission assembly 6 and the oil pipe string 41, and under the pressure of the power fluid assembly, the power fluid moves upwards to drive the motor rotor 52 to rotate, so that the power fluid finally moves upwards to an oil pipe chamber above the screw motor assembly 5.
It should be noted that, in order to enable the production fluid to reach the oil chamber through the axial fluid passage 521 inside the motor rotor 52, the inner diameter of the axial fluid passage 521 is greater than a first specified inner diameter threshold value, where when the inner diameter of the axial fluid passage 521 is greater than the first specified threshold value, the production fluid can reach the oil chamber through the axial fluid passage 521 inside the motor rotor 52, and the pumping oil yield reaches a required yield, for example, the specified threshold value may be 24 mm. Of course, in practical applications, the inner diameter of the axial liquid passing channel 521 is smaller than a second specified inner diameter threshold, which is determined by the diameter of the motor stator, and when the inner diameter of the axial liquid passing channel 521 is the second specified inner diameter threshold, the strength of the motor stator needs to meet the use requirement.
Illustratively, the motor stator 51 is connected to the oil tube assembly 4 by a threaded connection.
Alternatively, as shown in fig. 3, the transmission assembly 6 includes: the screw pump comprises a transmission assembly shell 61, a transmission shaft 62 and a thrust bearing 63, wherein one end of the transmission assembly shell 61 is connected with the bottom end of the motor stator 51, the other end of the transmission assembly shell 61 is connected with the screw pump 7, one end of the transmission shaft 62 is connected with the bottom end of a motor rotor, and the other end of the transmission shaft 62 is connected with a rotor of the screw pump 7.
As shown in fig. 4, the transmission assembly housing 61 is provided with a first radial fluid through hole 611, and the power fluid in the oil jacket annulus enters the interior of the transmission assembly 6 through the first radial fluid through hole 611. The transmission shaft 62 is provided with a second radial liquid passing hole 621 and a central hole liquid passing channel 622, the second radial liquid passing hole 621 is communicated with the central hole liquid passing channel 622, the production liquid enters the axial liquid passing channel 521 through the second radial liquid passing hole 621 and the central hole liquid passing channel 622, and the thrust bearing 63 is positioned above the second radial liquid passing hole 621 so as to isolate the power liquid from the production liquid in the transmission assembly 6.
The thrust bearing 63 divides the space between the transmission assembly housing 61 and the transmission shaft 62 into an upper space and a lower space, the power fluid enters the upper space through the first radial fluid passing hole 611, and the production fluid enters the lower space through the screw pump 7.
For example, the transmission assembly 61, the motor stator 51 and the screw pump 7 are connected by threads, and the transmission shaft 62, the motor rotor and the rotor of the screw pump 7 are connected by couplings, flexible shafts and the like.
Alternatively, as shown in fig. 5, the power fluid circulation assembly 1 includes: a liquid storage tank 11, a high-pressure plunger pump 12, a sand removing device 13 and a gas-liquid separator 14;
a liquid outlet of the liquid storage tank 11 is connected with a liquid inlet of the high-pressure plunger pump 12, a liquid outlet of the high-pressure plunger pump 12 is connected with the wellhead mechanism assembly 1, and power liquid in the liquid storage tank 11 is conveyed into an oil sleeve annulus through the wellhead mechanism assembly 2 after being pressurized by the high-pressure plunger pump 12;
a liquid inlet of the sand removing device 13 is connected with the wellhead mechanism assembly 1, a liquid outlet of the sand removing device 13 is connected with a liquid inlet of the gas-liquid separator 14, a liquid outlet of the gas-liquid separator 14 is connected with a liquid inlet of the liquid storage tank 11, the sand removing device 13 removes sand from the mixed liquid conveyed by the wellhead mechanism assembly and conveys the liquid after sand removal to the gas-liquid separator 14, and the gas-liquid separator 14 separates gas from the liquid after sand removal and conveys the residual liquid after separation to the liquid storage tank 11 as power liquid.
Wherein, the liquid outlet of high pressure plunger pump 12 and sleeve gate 24 pass through the pipeline intercommunication, and high pressure plunger pump 12 injects the oil jacket annular space through sleeve gate 24 through the pipeline after with the power liquid pressurization. The liquid inlet of the desanding device 13 is communicated with the oil pipe gate 22 through a pipeline, and the mixed liquid enters the desanding device 13 through the oil pipe gate 22 and the pipeline.
Optionally, as shown in fig. 6, the power fluid circulation assembly 1 further includes: the device comprises a flow meter 15, a first pressure gauge 16, a return valve 17, a second pressure gauge 18, an electromagnetic valve 19 and a liquid level meter 10;
a flow meter 15 installed between the reservoir tank 11 and the high-pressure plunger pump 12 for detecting the flow rate of the power fluid flowing from the reservoir tank 11 into the high-pressure plunger pump 12;
the first pressure gauge 16 is arranged between the high-pressure plunger pump 12 and the casing gate 24 and used for detecting the pressure of the power fluid in a pipeline between the high-pressure plunger pump 12 and the casing gate 24, a return pipeline is arranged between the high-pressure plunger pump 12 and the liquid storage tank 11, the return valve 17 is arranged on the return pipeline, and when the first pressure gauge 16 detects that the pressure of the power fluid in the pipeline between the high-pressure plunger pump 12 and the casing gate 24 is larger than a specified pressure threshold value, the return valve 17 is opened, and the power fluid flows into the liquid storage tank 11 through the return pipeline;
the second pressure gauge 18 is arranged between the oil pipe gate 12 and the desanding device 13 and is used for detecting the pressure of the mixed liquid in the pipeline between the oil pipe gate 12 and the desanding device 13;
the level gauge 10 is installed in the liquid storage pot 11, a liquid level height for detecting in the liquid storage pot 11, solenoid valve 19 is installed between desanding device 13 and gas-liquid separator 14, when the level gauge 10 detects also for highly being greater than first appointed liquid level height in the liquid storage pot 11, solenoid valve 19 closes, when the level gauge 10 detects that the liquid level height in the liquid storage pot 11 is less than second appointed liquid level height, solenoid valve 19 opens, so, the liquid level height of the power fluid in the liquid storage pot 11 remains throughout in second appointed liquid level height to first appointed liquid level height within range, the safety has both been guaranteed, the production needs have also been guaranteed.
Wherein, the desanding device 13 comprises a desander 131 and a sand settling tank 132, and the bottom of the sand settling tank 132 is provided with a sand discharge port.
In the embodiment of the invention, the oil well lifting system is driven to work through hydraulic power, so that the problems of motor temperature rise, motor burnout, cable breakdown and the like caused by the fact that the flow rate of production liquid cannot reach the cooling flow rate of a motor shell due to low liquid production volume of an oil well in the oil pumping process of a large-inclination low-liquid-volume oil well when the electric submersible pump lifting system is used are avoided. The power liquid circulating assembly realizes the recycling of the power liquid, avoids the problem that a special power liquid station needs to be equipped when a hydraulic drive lifting system is used, and solves the problems that the hydraulic drive screw oil extraction device has strong dependence on ground water and the power liquid station and the use condition is limited. The screw motor assembly conveys power fluid into an oil pipe cavity under the action of the power fluid in the oil sleeve annulus, the transmission assembly drives the screw pump to work under the driving of the screw motor assembly, the screw pump conveys production fluid in an oil well into the oil pipe cavity through the screw motor assembly so as to mix the power fluid with the production fluid to obtain mixed fluid, and the mixed fluid is conveyed to the ground, wherein the oil pipe cavity is a cavity formed between the screw motor assembly and a wellhead mechanism assembly in the oil pipe assembly, so that the production fluid and the power fluid respectively enter the oil pipe cavity from the screw motor assembly before mixing, namely, the movement directions of the production fluid and the power fluid are the same before mixing. The problem of because power liquid and production fluid motion direction before mixing are opposite, when the proportion of power liquid in the mixed solution is great, can restrain the output of production fluid is solved, the efficiency of lifting has been improved.
FIG. 7 is a flow chart of a method of pumping oil from a well lift system according to an exemplary embodiment of the present invention, as shown in FIG. 7, the method comprising:
step 701, injecting power fluid into an oil casing annulus through a wellhead mechanism assembly by a power fluid circulation assembly, wherein the oil casing annulus is an annulus formed among a first tubing string, a screw motor assembly, a transmission assembly, a screw pump, a second tubing string and a casing.
And 702, under the action of power fluid in the oil sleeve annulus, conveying the power fluid into an oil pipe chamber by the screw motor assembly, and driving the transmission assembly to rotate, wherein the oil pipe chamber is a chamber formed among the first oil pipe string, the screw motor assembly and the wellhead mechanism assembly.
And 703, driving the screw pump to work by the transmission assembly under the driving of the screw motor assembly.
Step 704, the screw pump conveys production fluid in the oil well into the oil pipe cavity through the screw motor assembly in the working process so as to mix the power fluid and the production fluid to obtain mixed fluid, and the mixed fluid is conveyed to the ground and the power fluid circulation assembly.
Step 705, the power fluid circulation assembly separates liquid from the mixed liquid, and returns to step 701 with the separated liquid as power fluid.
In the embodiment of the invention, the oil well lifting system is driven to work through hydraulic power, so that the problems of motor temperature rise, motor burnout, cable breakdown and the like caused by the fact that the flow rate of production liquid cannot reach the cooling flow rate of a motor shell due to low liquid production volume of an oil well in the oil pumping process of a large-inclination low-liquid-volume oil well when the electric submersible pump lifting system is used are avoided. The power liquid circulating assembly realizes the recycling of the power liquid, avoids the problem that a special power liquid station needs to be equipped when a hydraulic drive lifting system is used, and solves the problems that the hydraulic drive screw oil extraction device has strong dependence on ground water and the power liquid station and the use condition is limited. The screw motor assembly conveys power fluid into an oil pipe cavity under the action of the power fluid in the oil sleeve annulus, the transmission assembly drives the screw pump to work under the driving of the screw motor assembly, the screw pump conveys production fluid in an oil well into the oil pipe cavity through the screw motor assembly so as to mix the power fluid with the production fluid to obtain mixed fluid, and the mixed fluid is conveyed to the ground, wherein the oil pipe cavity is a cavity formed between the screw motor assembly and a wellhead mechanism assembly in the oil pipe assembly, so that the production fluid and the power fluid respectively enter the oil pipe cavity from the screw motor assembly before mixing, namely, the movement directions of the production fluid and the power fluid are the same before mixing. The problem of because power liquid and production fluid motion direction before mixing are opposite, when the proportion of power liquid in the mixed solution is great, can restrain the output of production fluid is solved, the efficiency of lifting has been improved.
FIG. 8 is a flow chart of another method of pumping oil from a well lift system according to an exemplary embodiment of the present invention, as shown in FIG. 8, comprising:
step 801, a high-pressure plunger pump included in the power fluid circulation assembly sucks power fluid from a fluid storage tank included in the power fluid circulation assembly and pressurizes the power fluid.
The high-pressure plunger pump is communicated with the liquid storage tank through a pipeline, and a flowmeter is arranged between the high-pressure plunger pump and the liquid storage tank and used for detecting the flow of liquid between the high-pressure plunger pump and the liquid storage tank.
It should be noted that when the oil well lifting system starts to work, the liquid storage tank is filled with water in advance, that is, during the first working cycle, the power fluid is externally filled water, and during the subsequent working cycle, the liquid in the liquid storage tank is the production fluid which enters the power fluid circulation assembly through the wellhead mechanism assembly, that is, during the subsequent working cycle, the power fluid is the production fluid which is recycled.
And step 802, injecting the pressurized power fluid into the oil casing annulus through a casing gate of a wellhead mechanism at a specified displacement by using a high-pressure plunger pump.
The high-pressure plunger pump is communicated with the oil sleeve annulus through the sleeve gate, the sleeve gate is opened during operation, power fluid enters the oil sleeve annulus through the sleeve gate, and the power fluid in the liquid storage tank is pressurized by the high-pressure plunger pump and then is injected into the oil sleeve annulus through the sleeve gate.
It should be noted that before the high-pressure plunger pump injects power fluid into the oil jacket annulus through the wellhead mechanism assembly at a specified displacement, the required rotating speed of the screw pump can be determined according to the liquid supply capacity of the oil well production layer, and the required displacement of the screw motor assembly is further determined. The displacement required by the screw motor assembly is the designated displacement of the high-pressure plunger pump for injecting power liquid into the oil sleeve ring in the air through the wellhead mechanism assembly.
In practical application, the discharge capacity of the high-pressure plunger pump can be detected through a flow meter arranged between the liquid storage tank and the high-pressure power pump, and the rotating speed of a variable frequency motor of the high-pressure plunger pump is adjusted according to a detection result, so that the discharge capacity of the high-pressure plunger pump is the same as the specified discharge capacity.
It is worth noting that in order to guarantee the safety of the high-pressure plunger pump, the pressure between the high-pressure plunger pump and the wellhead mechanism assembly needs to be controlled, therefore, a backflow pipeline is arranged between a liquid outlet of the high-pressure plunger pump and a liquid inlet of the gas storage tank, a backflow valve is installed on the backflow pipeline, when the first pressure gauge detects that the pressure between the high-pressure plunger pump and the wellhead mechanism assembly is larger than a specified pressure threshold value, the backflow valve is opened, and power liquid flows back to the liquid storage tank to adjust the pressure between the high-pressure plunger pump and the wellhead mechanism assembly.
And 803, under the action of the power fluid in the oil sleeve annulus, the screw motor assembly conveys the power fluid into an oil pipe cavity and drives the transmission assembly to rotate, wherein the oil pipe cavity is a cavity formed among the first oil pipe string, the screw motor assembly and the wellhead mechanism assembly.
The screw motor assembly converts pressure energy carried by power fluid entering the screw motor assembly through the transmission assembly into mechanical energy, and the motor rotor rotates under the driving of the mechanical energy. Specifically, the process of converting the pressure energy carried by the power fluid into mechanical energy is as follows: the power fluid enters a space between a motor rotor and a motor stator through an oil sleeve annulus and a first radial fluid passing hole in a transmission assembly shell under the driving of a power fluid circulation assembly, the power fluid spirally rises in the space and enters an oil pipe chamber, and the power fluid drives the motor rotor to rotate in the rising process.
And step 804, the transmission assembly drives the screw pump to work under the driving of the screw motor assembly.
The bottom end of the motor rotor is connected with one end of a transmission shaft in the transmission assembly, the other end of the transmission shaft is connected with the screw pump, the transmission shaft is driven to rotate when the motor rotor rotates, and the transmission shaft drives the screw pump to work.
Step 805, the screw pump conveys production fluid in the oil well into the oil pipe cavity through the screw motor assembly in the working process so as to mix the power fluid and the production fluid to obtain a mixed fluid, and the mixed fluid is conveyed to the ground and the power fluid circulation assembly.
The screw pump comprises a screw and a screw pump body, wherein a plurality of closed cavities are formed in the screw and the screw pump body in the screw pump, the volumes of the cavities can periodically change along with the rotation of the screw when the screw rotates, when oil pumping is started, production liquid firstly enters the closed cavity at the bottommost end of the screw pump and periodically increases and decreases along with the rotation of the screw, the production liquid is sucked into the cavity when the volume of the closed cavity at the bottommost end of the screw pump increases, the production liquid is pressed into the adjacent cavities above the cavity when the volume of the cavity decreases, the production liquid is sequentially conveyed in the closed cavities of the screw pump, and finally conveyed into an oil pipe cavity through the screw motor assembly.
Optionally, the production fluid delivered by the screw pump may enter the central bore fluid passage through a second radial fluid passage hole on the transmission shaft, and enter the oil pipe chamber through the central bore fluid passage and the axial fluid passage.
It should be noted that a part of the mixed liquid enters the desanding device through the first oil pipe gate to be used as power liquid for the next work cycle, and the other part of the mixed liquid is conveyed to the ground oil transportation equipment or the oil storage equipment through the second oil pipe gate.
Step 806, after the mixed liquid is conveyed to the desanding device included in the power fluid circulation assembly, the desanding device desands the mixed liquid, and the desanded mixed liquid is conveyed to the gas-liquid separator included in the power fluid circulation assembly.
Because the production fluid is the production fluid in the oil well, so the grit in the oil well can be mixed in the production fluid, in order to prevent that in next work cycle, carry the grit in the mixed liquor as power fluid, cause destruction to high pressure plunger pump, need the sand removal device to carry out the sand removal to the mixed liquor. Wherein, the sand removal device communicates through first oil pipe gate and oil pipe cavity, and the mixture in the oil pipe cavity gets into the sand removal device through first oil pipe gate, and the sand removal device carries out the sand removal to mixed liquid.
In step 807, after the desanded mixed solution is sent to the gas-liquid separator, the gas-liquid separator separates the liquid and the gas in the desanded mixed solution, and sends the separated liquid to the liquid storage tank.
Because natural gas may be mixed in the mixed liquid, if the natural gas enters the screw motor assembly in the next working cycle, the natural gas can directly escape from the hole between the motor stator and the motor rotor, and the motor rotor cannot be driven to rotate, so that the driving efficiency of the power liquid driving motor rotor is influenced.
Therefore, the mixed liquid after sand removal is conveyed to the gas-liquid separator, the gas-liquid separator separates gas in the mixed liquid after sand removal, and the residual liquid is conveyed to the liquid storage tank for the next working cycle.
Optionally, the level gauge detects the liquid level height in the liquid storage pot, when the level gauge detects that the liquid level height in the liquid storage pot is greater than first appointed liquid level height, the solenoid valve is closed, when the level gauge detects that the liquid level height in the liquid storage pot is less than second appointed liquid level height, the solenoid valve is opened, so, the liquid level height of the power liquid in the liquid storage pot remains throughout in second appointed liquid level height to first appointed liquid level height within range, has both guaranteed the security, has also guaranteed the production needs.
In the embodiment of the invention, the oil well lifting system is driven to work through hydraulic power, so that the problems of motor temperature rise, motor burnout, cable breakdown and the like caused by the fact that the flow rate of production liquid cannot reach the cooling flow rate of a motor shell due to low liquid production volume of an oil well in the oil pumping process of a large-inclination low-liquid-volume oil well when the electric submersible pump lifting system is used are avoided. The power liquid circulating assembly realizes the recycling of the power liquid, avoids the problem that a special power liquid station needs to be equipped when a hydraulic drive lifting system is used, and solves the problems that the hydraulic drive screw oil extraction device has strong dependence on ground water and the power liquid station and the use condition is limited. The screw motor assembly conveys power fluid into an oil pipe cavity under the action of the power fluid in the oil sleeve annulus, the transmission assembly drives the screw pump to work under the driving of the screw motor assembly, the screw pump conveys production fluid in an oil well into the oil pipe cavity through the screw motor assembly so as to mix the power fluid with the production fluid to obtain mixed fluid, and the mixed fluid is conveyed to the ground, wherein the oil pipe cavity is a cavity formed between the screw motor assembly and a wellhead mechanism assembly in the oil pipe assembly, so that the production fluid and the power fluid respectively enter the oil pipe cavity from the screw motor assembly before mixing, namely, the movement directions of the production fluid and the power fluid are the same before mixing. The problem of because power liquid and production fluid motion direction before mixing are opposite, when the proportion of power liquid in the mixed solution is great, can restrain the output of production fluid is solved, the efficiency of lifting has been improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (6)

1. A well lifting system, comprising: power fluid circulation assembly, well head mechanism assembly, sleeve pipe, oil pipe assembly, screw motor assembly, transmission assembly and screw pump, oil pipe assembly includes first oil pipe cluster and second oil pipe cluster, well head mechanism assembly includes: the well head mechanism comprises a well head mechanism main body, a first oil pipe gate, a second oil pipe gate and a casing pipe gate;
the power fluid circulation assembly is connected with the wellhead mechanism assembly, the wellhead mechanism main body is respectively connected with the casing and the first oil pipe string, the first oil pipe gate and the second oil pipe gate are respectively communicated with the oil pipe assembly through the wellhead mechanism main body, the casing gate is communicated with the oil casing annulus through the wellhead mechanism main body, the wellhead mechanism assembly is in bolted connection or extrusion contact connection with the casing, a sealing washer is arranged between the wellhead mechanism assembly and the casing pipe, the first tubing string, the screw motor assembly, the transmission assembly, the screw pump and the second tubing string are sequentially connected, the first tubing string, the screw motor assembly, the transmission assembly, the screw pump and the second tubing string are positioned inside the casing, and an oil casing annulus is formed between the first tubing string, the screw motor assembly, the transmission assembly, the screw pump and the second tubing string;
the power fluid circulation assembly is used for injecting power fluid into the transmission assembly through the oil sleeve annulus through the wellhead mechanism assembly, the screw motor assembly conveys the power fluid into an oil pipe cavity under the action of the power fluid and drives the transmission assembly to rotate, the transmission assembly drives the screw pump under the driving of the screw motor assembly, production fluid in an oil well is conveyed into the oil pipe cavity through the screw motor assembly by the screw pump so as to be mixed with the power fluid, mixed liquid is obtained, and the oil pipe cavity is a cavity formed among the first oil pipe string, the screw motor assembly and the wellhead mechanism assembly;
after the mixed liquid is conveyed to the power liquid circulation assembly through the oil pipe chamber, the power liquid circulation assembly is further used for separating liquid from the mixed liquid and recycling the separated liquid as the power liquid;
the power fluid circulation assembly comprises: the device comprises a gas-liquid separator, a desanding device, a liquid storage tank, a high-pressure plunger pump, a flowmeter, a first pressure gauge, a reflux valve, a second pressure gauge, a liquid level meter and an electromagnetic valve;
the liquid outlet of the liquid storage tank is connected with the liquid inlet of the high-pressure plunger pump, the liquid outlet of the high-pressure plunger pump is connected with the wellhead mechanism assembly, and power liquid in the liquid storage tank is conveyed into the oil sleeve annulus through the wellhead mechanism assembly after being pressurized by the high-pressure plunger pump;
the liquid inlet of the desanding device is connected with the wellhead mechanism assembly, the liquid outlet of the desanding device is connected with the liquid inlet of the gas-liquid separator, the liquid outlet of the gas-liquid separator is connected with the liquid inlet of the liquid storage tank, the desanding device is used for desanding the mixed liquid conveyed by the wellhead mechanism assembly and conveying the desanded liquid to the gas-liquid separator, and the gas-liquid separator is used for separating gas from the desanded liquid and conveying the remaining liquid after separation to the liquid storage tank as the power liquid;
the desanding device comprises a desander and a sand settling tank, a liquid outlet of the desander is connected with a liquid inlet of the gas-liquid separator, and a sand discharge port is formed in the bottom of the sand settling tank;
the flowmeter is positioned between the liquid storage tank and the high-pressure plunger pump, and is used for detecting the discharge capacity of the high-pressure plunger pump, and the discharge capacity detected by the flowmeter is used for adjusting the rotating speed of a variable frequency motor of the high-pressure plunger pump;
the first pressure gauge is positioned between the high-pressure plunger pump and the casing gate and is used for detecting the pressure of power liquid in a pipeline between the high-pressure plunger pump and the casing gate of the wellhead mechanism assembly; a backflow pipeline is arranged between the high-pressure plunger pump and the liquid storage tank, the backflow valve is positioned on the backflow pipeline, and the backflow valve is used for being opened when the pressure detected by the first pressure gauge is greater than a specified pressure threshold value;
the second pressure gauge is positioned between the first oil pipe gate and the desanding device and used for detecting the pressure of mixed liquid in a pipeline between the first oil pipe gate and the desanding device;
the liquid level meter is positioned in the liquid storage tank and is used for detecting the liquid level height in the liquid storage tank; the electromagnetic valve is located between the desanding device and the gas-liquid separator, the electromagnetic valve is used for being closed when the liquid level height detected by the liquid level meter is greater than a first specified liquid level height, and the electromagnetic valve is also used for being opened when the liquid level height detected by the liquid level meter is less than a second specified liquid level height.
2. The well lift system of claim 1, wherein said tubing assembly further comprises: the packer and the anti-rotation anchoring mechanism;
the packer and the anti-rotation anchoring mechanism are respectively connected with the second oil pipe string, the packer is located above the anti-rotation anchoring mechanism, and the anti-rotation anchoring mechanism is close to the bottom end of the second oil pipe string.
3. The well lift system of claim 1, wherein said screw motor assembly comprises: a motor stator and a motor rotor;
the top end of the motor stator is connected with the first oil pipe string, the bottom end of the motor stator is connected with the transmission assembly, the motor rotor is located inside the motor stator, an axial liquid passing channel is arranged inside the motor rotor, and the bottom end of the motor rotor is connected with the transmission assembly.
4. A well lifting system as claimed in claim 1, wherein said transmission assembly comprises: the transmission assembly comprises a transmission assembly shell, a transmission shaft and a thrust bearing;
the top end of the transmission assembly shell is connected with a motor stator of the screw motor assembly, the bottom end of the transmission assembly shell is connected with the screw pump, and a first radial liquid passing hole is formed in the transmission assembly shell;
the top end of the transmission shaft is connected with a motor rotor included by the screw motor assembly, the bottom end of the transmission shaft is connected with the screw pump, a second radial liquid passing hole and a central hole liquid passing channel are arranged on the transmission shaft and communicated with the central hole liquid passing channel, and the thrust bearing is positioned above the second radial liquid passing hole so as to isolate the power liquid from the production liquid in the transmission assembly.
5. A method of pumping oil from an oil well lifting system, the method being used in an oil well lifting system according to any one of claims 1 to 4, the method comprising:
the power fluid circulation assembly injects power fluid into an oil casing annulus through the wellhead mechanism assembly, and the oil casing annulus is an annulus formed among the first tubing string, the screw motor assembly, the transmission assembly, the screw pump, the second tubing string and the casing;
under the action of power fluid in the oil sleeve annulus, the screw motor assembly conveys the power fluid into an oil pipe chamber and drives the transmission assembly to rotate, wherein the oil pipe chamber is a chamber formed among the first oil pipe string, the screw motor assembly and the wellhead mechanism assembly;
the transmission assembly is driven by the screw motor assembly to drive the screw pump to work;
in the working process of the screw pump, conveying production liquid in an oil well to the oil pipe chamber through the screw motor assembly so as to mix the power liquid with the production liquid to obtain mixed liquid, and conveying the mixed liquid to the ground and the power liquid circulation assembly;
the desanding device in the power fluid circulation assembly desalts the mixed liquid conveyed by the wellhead mechanism assembly, conveys the desanded liquid to the gas-liquid separator in the power fluid circulation assembly, separates gas from the desanded liquid, and conveys the remaining liquid serving as power fluid to a liquid storage tank in the power fluid circulation assembly;
a flow meter in the power liquid circulation assembly detects the discharge capacity of a high-pressure plunger pump in the power liquid circulation assembly, and the discharge capacity detected by the flow meter is used for adjusting the rotating speed of a variable frequency motor of the high-pressure plunger pump;
a first pressure gauge in the power fluid circulation assembly detects the pressure of power fluid in a pipeline between the high-pressure plunger pump and a casing gate of the wellhead mechanism assembly, and a return valve in the power fluid circulation assembly is opened when the pressure measured by the first pressure gauge is greater than a specified pressure threshold value;
a second pressure gauge in the power fluid circulation assembly detects the pressure of the mixed liquid in the pipeline between the first oil pipe gate of the wellhead mechanism assembly and the desanding device;
a liquid level meter in the power liquid circulation assembly detects the liquid level height in the liquid storage tank, when the liquid level height detected by the liquid level meter is greater than a first specified liquid level height, an electromagnetic valve in the power liquid circulation assembly is closed, and when the liquid level height detected by the liquid level meter is less than a second specified liquid level height, the electromagnetic valve in the power liquid circulation assembly is opened;
and the high-pressure plunger pump pressurizes the power fluid and then returns the power fluid circulation assembly to inject the power fluid into the oil sleeve annulus through the wellhead mechanism assembly.
6. The method of claim 5, wherein the power fluid circulation assembly injects power fluid into the oil casing annulus through a wellhead mechanism assembly, comprising:
the high-pressure plunger pump sucks the power liquid from the liquid storage tank and pressurizes the power liquid;
and the high-pressure plunger pump injects the pressurized power fluid into the oil casing annulus through a casing gate of the wellhead mechanism assembly at a specified displacement.
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CN110344752B (en) * 2019-07-10 2020-12-15 西南石油大学 Double-wall screw drilling system based on gas-liquid two-phase driving
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