A combination of an electric pump and a jet pump suitable for lifting a process pipe column with high sand content and a method of using the same

Abstract

The present invention provides a combined electric pump and jet pump lifting process string suitable for high-sand content production, and a method for using the same. The jet pump lifting release string is installed in an electric pump lifting Y-type production string. The electric pump lifting Y-type production string comprises, from top to bottom, an upper oil pipe, a special Y-joint, a lower oil pipe, a sand control device, a No. 1 production sleeve, a No. 2 production sleeve, and a round plug. The jet pump lifting release string comprises, from top to bottom, a small oil pipe, a release tool, a locking core tool, a jet pump, and a velocity tube. The string is composed of two strings, including an electric pump lifting Y-type production string and a jet pump lifting release string. When the sand content of the oil well output fluid is less than one thousandth, the electric pump is used to lift the Y-type production string. When the sand content of the oil well output fluid is greater than one thousandth, the jet pump lifting release string is inserted, forming a combined electric pump and jet pump lifting process string, which can achieve high-sand content well fluid lifting.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and natural gas extraction, and more particularly to a combined electric pump and jet pump lifting process pipe column suitable for high sand content and a method for using the same. Background Art

[0002] With the increase in the number of offshore fracturing wells, the problem of sand production in oil wells has become increasingly prominent. According to statistics, among the 20 screen-tube fracturing wells in Bohai, 11 wells had electric pump failures, accounting for 55% of the total number of wells. The average operation cycle of the electric pumps in the 20 screen-tube fracturing wells was 349 days, of which 11 electric pump wells had an average operation period of 217 days, which was far lower than the average oil well electric pump operation level after fracturing. After sampling and analysis, it was determined that sand production was the main cause of the electric pump failure in the screen-tube fracturing wells.

[0003] The sand content of existing conventional oil well electric pump production tubing cannot exceed one thousandth even if a sand-resistant electric pump is used for lifting well fluid. Moreover, long-term operation of the electric pump under this working condition will cause serious pump shaft wear and pump sticking without fluid, which greatly shortens the pump inspection cycle and reduces the economic efficiency of lifting such oil wells. Summary of the Invention

[0004] The present invention overcomes the shortcomings of the prior art. The existing pipe strings produced by conventional oil well electric pumps have serious pump shaft wear and pump stuck without liquid phenomena, greatly shortening the pump inspection cycle, and providing an electric pump and jet pump combined lifting process pipe string suitable for high sand content and a method of using the same. The pipe string consists of two pipe strings, including an electric pump lifting Y-shaped production pipe string and a jet pump lifting and releasing pipe string. When the sand content of the oil well output fluid is less than one thousandth, the electric pump is used to lift the Y-shaped production pipe string. When the sand content of the oil well output fluid is greater than one thousandth, the jet pump is lowered to lift the releasing pipe string, forming a combined electric pump and jet pump lifting process pipe string, which can achieve high sand content well fluid lifting.

[0005] The purpose of the present invention is achieved through the following technical solutions.

[0006] A combined electric pump and jet pump lifting process string suitable for high sand content, comprising an electric pump lifting Y-shaped production string and a jet pump lifting release string, wherein the jet pump lifting release string is installed in the electric pump lifting Y-shaped production string;

[0007] The electric pump lifting Y-type production string includes an upper oil pipe, a special Y-joint, a lower oil pipe, a sand control device, a No. 1 production sliding sleeve, a No. 2 production sliding sleeve and a round plug. The upper oil pipe and the lower oil pipe are both arranged in the casing. A top packer is arranged in the annulus between the upper oil pipe and the casing. A downhole safety valve is arranged on the upper oil pipe above the top packer. The upper oil pipe is connected to the lower oil pipe through the special Y-joint. A sand-resistant electric submersible pump unit is installed on the branch joint of the special Y-joint. A hanging step is formed on the inner wall of the special Y-joint for hanging a plug or a locking core tool. The sand control device is arranged on the lower oil pipe below the special Y-joint. A positioning seal, the No. 1 production sliding sleeve, an insert seal, the No. 2 production sliding sleeve and the round plug are arranged in sequence from top to bottom below the sand control device.

[0008] The jet pump lifting and releasing pipe string includes a small oil pipe, a releasing tool, a jet pump and a velocity tube. The tail end of the small oil pipe is connected to the outlet end of the jet pump through the releasing tool. A locking core tool is also provided between the releasing tool and the outlet end of the jet pump to suspend the jet pump lifting and releasing pipe string in a special Y-joint. The inlet end of the jet pump is connected to the velocity tube.

[0009] A landing joint is also provided on the upper oil pipe below the top packer.

[0010] The sand-resistant electric submersible pump unit is connected to a ground power supply via an electric pump cable.

[0011] A method for using a combination of an electric pump and a jet pump to lift a process string suitable for high sand content is performed in the following steps:

[0012] Step 1: When the sand content of the produced fluid of the oil well is less than one thousandth, the electric pump-lifted Y-shaped production string is lowered into the oil well. The positioning seal is connected to the top sealing section in the original wellbore, and the insertion seal is matched with the insertion sealing section of the original wellbore to complete the layered sealing. A plug is dropped into the electric pump-lifted Y-shaped production string to block the connecting passage between the special Y-joint and the lower oil pipe with the plug. At this time, the well fluid enters the annulus between the lower oil pipe and the casing through the sand control device, and then is pressurized by the sand-resistant electric submersible pump unit and directly enters the special Y-joint and the upper oil pipe, and then reaches the wellhead;

[0013] Step 2, when the sand content of the oil well production fluid is greater than one thousandth, after the plug is fished out, the jet pump lifting and releasing string is lowered into the above-mentioned electric pump lifting Y-type production string until the upper and lower seals of the jet pump core are matched with the seal inside the special Y joint, the locking core tool is released to fix the jet pump core and the velocity tube, and a ball is thrown into the jet pump lifting and releasing string to pressurize, and the releasing is completed. The releasing tool and the small oil pipe are taken out to form an electric pump and jet pump combination lifting sand-carrying production string. At this time, the formation production fluid at the No. 2 production sleeve flows mostly into the lower oil pipe through the No. 2 production sleeve, and a small part flows into the velocity tube. The formation produced fluid at the No. 1 production sleeve flows into the lower oil pipe through the No. 1 production sleeve. The formation produced fluid flowing into the lower oil pipe is filtered by the sand control device connected to the lower oil pipe. Most of the sand in the formation produced fluid is blocked and deposited in the pocket of the lower oil pipe. The filtered formation produced fluid enters the annulus between the lower oil pipe and the casing and is pressurized by the sand-resistant electric submersible pump unit and directly enters the special Y-joint and the upper oil pipe. A small amount of formation produced fluid flowing into the velocity pipe is pressurized by the velocity pipe and the jet pump and directly enters the special Y-joint and the upper oil pipe, and is mixed with the above-mentioned filtered formation produced fluid before being discharged to the wellhead.

[0014] After the sand-resistant electric submersible pump unit is started, the well fluid in the annulus between the lower oil pipe and the casing enters the power fluid end of the jet pump after being pressurized, and generates a negative pressure injection effect after passing through the jet pump nozzle, sucking the well fluid in the velocity tube. Since the velocity tube is in direct contact with the sand pocket, the well fluid with high sand content is carried to the jet pump suction chamber through the velocity tube and initially mixed with the power fluid in the throat pipe, and then flows through the oil pipe on the upper part of the diffuser to the wellhead. When the well fluid contains large sand particles or the output demand is large, the electric pump can be replenished through the oil casing annulus to ensure sufficient liquid volume at the power fluid end of the jet pump, which can produce a better negative pressure injection effect.

[0015] The beneficial effects of the present invention are: enhanced adaptability to the sand content of the lifting well fluid. The sand content of the lifting well fluid in the existing technology is less than one thousandth, but after adopting this process string, the sand content of the lifting well fluid can be increased to more than 5%; the displacement range of the lifting well fluid is enhanced, and the improved process string can adapt to low-liquid-volume lifting. The original string has low heat dissipation of the electric pump during low-liquid-volume lifting, which is prone to malfunction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the sand-carrying structure of the electric pump and jet pump combined in the present invention;

[0017] Figure 2 This is a schematic diagram of the structure of the jet pump lifting and releasing pipe column of the present invention;

[0018] Figure 3 It is a schematic diagram of the electric pump lifting structure of the present invention;

[0019] In the figure: A is the bottom sand; B is the oil casing annulus filling liquid; C is the oil casing annulus dynamic liquid level,

[0020] 1 is a downhole safety valve; 2 is a top packer; 3 is a casing; 4 is an upper oil pipe; 5 is an electric pump cable; 6 is a special Y-connector; 7 is a sand-resistant electric submersible pump unit; 8 is a sand control device; 9 is a landing joint; 10 is a jet pump core; 11 is a velocity tube; 12 is a positioning seal; 13 is a No. 1 production sleeve; 14 is an insert seal; 15 is a No. 2 production sleeve; 16 is a small oil pipe; 17 is a release tool; 18 is a core locking tool; 19 is a plug; and 20 is a lower oil pipe.

[0021] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below through specific embodiments.

[0023] A combined electric pump and jet pump lifting process string suitable for high sand content, comprising an electric pump lifting Y-shaped production string and a jet pump lifting release string, wherein the jet pump lifting release string is installed in the electric pump lifting Y-shaped production string;

[0024] The electric pump lift Y-type production string includes an upper oil pipe 4, a special Y-joint 6, a lower oil pipe 20, a sand control device 8, a No. 1 production sleeve 13, a No. 2 production sleeve 15 and a round plug. The upper oil pipe 4 and the lower oil pipe 20 are both arranged in the casing 3. A top packer 2 is provided in the annulus between the upper oil pipe 4 and the casing 3. A downhole safety valve 1 is provided on the upper oil pipe 4 above the top packer 2. The upper oil pipe 4 is connected to the lower oil pipe 20 through a special Y-joint 6. A sand-resistant electric submersible pump unit 7 is installed on the branch joint of the special Y-joint 6. A hanging step is formed on the inner wall of the special Y-joint 6 for hanging a plug 19 or a locking core tool 18. A sand control device 8 is provided on the lower oil pipe 20 below the special Y-joint 6. Below the sand control device 8, a positioning seal 12, a No. 1 production sleeve 13, an insert seal 14, a No. 2 production sleeve 15 and a round plug are provided in order from top to bottom.

[0025] The jet pump lifting and releasing string includes a small oil pipe 16, a releasing tool 17, a jet pump and a velocity tube 11. The tail end of the small oil pipe 16 is connected to the outlet end of the jet pump through the releasing tool 17. A locking tool 18 is also provided between the releasing tool 17 and the outlet end of the jet pump to suspend the jet pump lifting and releasing string in a special Y-joint 6. The inlet end of the jet pump is connected to the velocity tube 11.

[0026] A landing joint 9 is also provided on the upper oil pipe 4 below the top packer 2 .

[0027] The sand-resistant electric submersible pump unit 7 is connected to the surface power supply through the electric pump cable 5.

[0028] A method for using a combination of an electric pump and a jet pump to lift a process string suitable for high sand content is performed in the following steps:

[0029] Step 1: When the sand content of the produced fluid of the oil well is less than one thousandth, the electric pump lift Y-shaped production string is lowered into the oil well. The positioning seal 12 is disconnected from the top seal in the original wellbore, and the insert seal 14 cooperates with the insert seal section of the original wellbore to complete the layered sealing. A plug 19 is dropped into the electric pump lift Y-shaped production string to block the communication channel between the special Y-joint 6 and the lower oil pipe 20. At this time, the well fluid enters the annulus between the lower oil pipe 20 and the casing 3 through the sand control device 8, and is then pressurized by the sand-resistant electric submersible pump unit 7 and directly enters the special Y-joint 6 and the upper oil pipe 4, and then reaches the wellhead;

[0030] Step 2, when the sand content of the oil well production fluid is greater than one thousandth, after the plug 19 is fished out, the jet pump lifting and releasing string is lowered into the above-mentioned electric pump lifting Y-type production string until the upper and lower seals of the jet pump core 10 are matched with the seal inside the special Y-joint 6, the lock core tool 18 is released to fix the jet pump core 10 and the velocity tube 11, and a ball is thrown into the jet pump lifting and releasing string to pressurize, and the releasing is completed. The releasing tool 17 and the small oil pipe 16 are taken out to form an electric pump and jet pump combination lifting sand-carrying production string. At this time, the formation production fluid at the No. 2 production sleeve 15 flows mostly into the lower oil pipe through the No. 2 production sleeve 15, and a small part flows into the velocity tube 11. The formation production fluid at the production sleeve 13 flows into the lower oil pipe 11 through the No. 1 production sleeve 13. The formation production fluid flowing into the lower oil pipe 11 is filtered by the sand control device 8 connected to the lower oil pipe 20. Most of the sand in the formation production fluid is blocked and deposited in the pocket of the lower oil pipe 20. The filtered formation production fluid enters the annulus between the lower oil pipe 20 and the casing 3 and is pressurized by the sand-resistant electric submersible pump unit 7 and directly enters the special Y-joint 6 and the upper oil pipe 4. A small amount of formation production fluid flowing into the velocity pipe 11 is pressurized by the velocity pipe 11 and the jet pump and directly enters the special Y-joint 6 and the upper oil pipe 4, and is mixed with the above-mentioned filtered formation production fluid before reaching the wellhead.

[0031] After the sand-resistant electric submersible pump unit is started, the well fluid in the annulus between the lower oil pipe and the casing enters the power fluid end of the jet pump after being pressurized, and generates a negative pressure injection effect after passing through the jet pump nozzle, sucking the well fluid in the velocity tube. Since the velocity tube is in direct contact with the sand pocket, the well fluid with high sand content is carried to the jet pump suction chamber through the velocity tube and initially mixed with the power fluid in the throat pipe, and then flows through the oil pipe on the upper part of the diffuser to the wellhead. When the well fluid contains large sand particles or the output demand is large, the electric pump can be replenished through the oil casing annulus to ensure sufficient liquid volume at the power fluid end of the jet pump, which can produce a better negative pressure injection effect.

[0032] For ease of explanation, spatial relative terms such as "upper", "lower", "left", and "right" are used in the embodiments to illustrate the relationship between one element or feature shown in the figures and another element or feature. It should be understood that, in addition to the orientation shown in the figures, spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figure is inverted, the element described as being "under" other elements or features will be positioned "above" other elements or features. Therefore, the exemplary term "under" can include both upper and lower orientations. The device can be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here can be interpreted accordingly.

[0033] Moreover, relational terms such as “first” and “second” are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any actual relationship or order between these components.

[0034] The present invention has been described in detail above, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A combination of an electric pump and a jet pump for lifting a process string with high sand content, characterized by: It includes an electric pump lifting Y-type production string and a jet pump lifting and releasing string, wherein the jet pump lifting and releasing string is installed in the electric pump lifting Y-type production string; The electric pump lifting Y-type production string includes an upper oil pipe, a special Y-joint, a lower oil pipe, a sand control device, a No. 1 production sliding sleeve, a No. 2 production sliding sleeve and a round plug. The upper oil pipe and the lower oil pipe are both arranged in the casing. A top packer is arranged in the annulus between the upper oil pipe and the casing. A downhole safety valve is arranged on the upper oil pipe above the top packer. The upper oil pipe is connected to the lower oil pipe through the special Y-joint. A sand-resistant electric submersible pump unit is installed on the branch joint of the special Y-joint. A hanging step is formed on the inner wall of the special Y-joint for hanging a plug or a locking core tool. The sand control device is arranged on the lower oil pipe below the special Y-joint. A positioning seal, the No. 1 production sliding sleeve, an insert seal, the No. 2 production sliding sleeve and the round plug are arranged in sequence from top to bottom below the sand control device. The jet pump lifting and releasing pipe string includes a small oil pipe, a releasing tool, a jet pump and a velocity tube. The tail end of the small oil pipe is connected to the outlet end of the jet pump through the releasing tool. A locking core tool is also provided between the releasing tool and the outlet end of the jet pump to suspend the jet pump lifting and releasing pipe string in a special Y-joint. The inlet end of the jet pump is connected to the velocity tube.

2. The electric pump and jet pump combination for lifting a process string with high sand content according to claim 1, characterized in that: A landing joint is also provided on the upper oil pipe below the top packer.

3. The electric pump and jet pump combination for lifting a process string with high sand content according to claim 1, characterized in that: The sand-resistant electric submersible pump unit is connected to a ground power supply via an electric pump cable.

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