Spiral conveying multiphase flow device for shale oil well and operation control method

Abstract

The invention discloses a spiral conveying multiphase flow device for a shale oil well and an operation control method. The problems that in the oil extraction process of an existing electric submersible pump, sand blocking, scale blocking and airlock phenomena are prone to occurring are mainly solved. The device is characterized in that the lower part of the wellhead (9) is connected with a vertical spiral conveying pump (4) through an oil pipe (6), and the bottom of the vertical spiral conveying pump (4) is connected with a submersible motor (2); the system further comprises an underground working condition monitoring unit and a ground data acquisition unit (8), the underground working condition monitoring unit comprises a multi-parameter sensor (1) located at the bottom of the submersible motor (2), and the multi-parameter sensor (1) is connected with the ground data acquisition unit (8) through a cable (7). According to the method, the phenomena of sand blocking, scale blocking and gas locking of the electric submersible pump in the shale oil reservoir oil extraction process are avoided, multiphase medium mixed pumping is achieved, the unit operation time rate is increased, and continuous production of an oil well is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of oil exploitation, in particular to a spiral conveying multiphase flow device for shale oil wells and an operation control method. Background Art

[0002] In recent years, shale oil reservoirs have been developed on a certain scale. The development method adopts horizontal wells plus volume fracturing. Submersible electric pumps are one of the main artificial lifting equipment in the early stage of drainage and production. During the application process, they are affected by media such as sand, gas, and scale in the well fluid, which can easily cause sand jamming overload shutdown, gas lock underload shutdown, and flow channel scaling blockage. The operating rate and efficiency of submersible electric pumps are low under complex working conditions. In severe cases, the only way is to inspect the pump and replace the lifting equipment, and the continuous production of shale oil wells cannot be guaranteed. Summary of the invention

[0003] In order to overcome the problems of sand sticking, scale sticking and gas lock occurring during the oil production process of existing submersible electric pumps, the present invention provides a spiral conveying multiphase flow device and an operation control method for shale oil wells, which avoids the sand sticking, scale sticking and gas lock occurring during the oil production process of shale oil reservoirs of the submersible electric pumps, realizes multiphase medium mixed extraction, improves the operation rate of the unit, and ensures continuous production of the oil wells.

[0004] The technical solution of the present invention is: a spiral conveying multiphase flow device for shale oil wells, including a wellhead, a vertical spiral conveying pump is connected to the bottom of the wellhead through an oil pipe, and the bottom of the vertical spiral conveying pump is connected to a submersible motor; it also includes a downhole condition monitoring unit and a ground data acquisition unit, the downhole condition monitoring unit includes a multi-parameter sensor located at the bottom of the submersible motor, and the multi-parameter sensor is connected to the ground data acquisition unit through a cable.

[0005] The vertical screw conveying pump is formed by connecting a plurality of sections of single screw conveying pumps. The single screw conveying pump comprises an upper joint and a lower joint, and a shell is connected between the upper joint and the lower joint. A moving screw is arranged inside the shell, and spiral blades are arranged outside the moving screw.

[0006] A stationary screw sleeve is inlaid on the inner wall of the shell. A spiral annular groove is arranged on the inner wall of the stationary screw sleeve in the opposite direction of the spiral blade. The number of the spiral annular grooves is the same as that of the spiral blade. The moving screw and the spiral blade are located inside the stationary screw sleeve.

[0007] The outer surface of the lower joint of the lowermost single screw conveying pump in the vertical screw conveying pump is provided with a well fluid filter screen, and a liquid inlet is opened on the side wall of the lower joint, and the mixed liquid enters the vertical screw conveying pump through the liquid inlet.

[0008] The shaft diameter d of the movable screw is determined by the following steps:

[0009] Step S1, obtaining multiphase flow liquid density ρ, design flow rate Q, head H and rotation speed n;

[0010] Step S2: Calculate the power N of the moving screw shaft C :

[0011]

[0012] Where: N is the initial value of power; η is efficiency;

[0013] N C =1.2N

[0014] Where: 1.2 is the safety factor;

[0015] Step S3: Calculate the torque M of the moving screw shaft n :

[0016]

[0017] Step S4, calculate the shaft diameter d of the movable screw:

[0018]

[0019] Where: [τ] is the allowable shear stress.

[0020] It further includes: a current harmonic suppression unit for optimizing the output waveform of the variable frequency control system to make it close to a sine wave and reduce high-order harmonic components;

[0021] Downhole working condition monitoring unit, used to obtain the inlet pressure and outlet pressure of the vertical screw conveying pump, the motor temperature and well fluid temperature of the submersible motor, X / Y / Z axial vibration, current leakage and insulation resistance of the screw conveying multiphase flow device;

[0022] Surface data acquisition unit, used to monitor and collect casing pressure, oil pressure, temperature and production data;

[0023] The dynamic liquid level determination unit calculates the dynamic liquid level depth periodically based on the collected and processed data, and determines the frequency to be executed by the parameter adjustment method. The determination program is built into the control processing center;

[0024] The flow pressure drop determination unit calculates the bottom hole flow pressure drop periodically based on the collected and processed data, and determines the execution frequency and nozzle size by the parameter adjustment method. The determination program is built into the control processing center;

[0025] Fault self-diagnosis unit: based on the collected and processed data, determine the abnormal operating conditions according to the fault value and start the fault handling procedure;

[0026] On-site production application control panel: installed on the frequency conversion control system, used for parameter setting, operation data display, start / stop, fault / reset.

[0027] An operation control method of a spiral conveying multiphase flow device for a shale oil well comprises the following steps:

[0028] Step R1: Obtain the daily liquid production Q of the spiral conveying multiphase flow device at the initial stage of production 实 ;

[0029] Step R2: Obtain the hydraulic characteristic curve of the spiral conveying multiphase flow device and determine the daily liquid production Q 实 The corresponding operating frequency f;

[0030] Step R3: Calculate the dynamic liquid level H of the current spiral conveying multiphase flow device i ;

[0031] Step R4: Preset the optimal dynamic liquid level range H min ~H max , adjust the operating frequency f of the spiral conveying multiphase flow device so that H min ≤H i ≤H max ;

[0032] Step R5, taking n days as a statistical period, as a step frequency adjustment, repeating steps R3 and R4.

[0033] Further, in step R3,

[0034] H i =H1-(P 吸 -P 套 )g / ρ 混

[0035] Where: H1 is the depth of the pump suction port; P 吸 is the suction pressure; P 套 is the indication of the casing pressure acquisition unit; ρ 混 is the density of shale oil well fluid; g is the acceleration of gravity;

[0036] The shale oil well fluid density ρ 混 for

[0037] ρ 混 =ρ 水 ω+ρ 页 (1-ω)

[0038] Where: 页 is the density of shale oil; 水 is the density of water; ω is the water content of the well fluid.

[0039] Further, in step R4, if H i >H max , then reduce the operating frequency f, and use Δf as the frequency adjustment step. After the dynamic liquid surface is stable, calculate the depth H at the pump suction porti , wait for H min ≤H i ≤H max When , determine the target frequency f1, and run at the target frequency f1;

[0040] If H i <H min , then increase the operating frequency f, and use Δf as the frequency adjustment step. After the dynamic liquid surface is stable, calculate the depth H at the pump suction port i , wait for H min ≤H i ≤H max When the target frequency f2 is determined, the inverter operates at the target frequency f2.

[0041] The operation control method of the spiral multiphase flow conveying device for shale oil wells further includes:

[0042] Step R6: Calculate the bottom hole flow pressure drop rate P of the shale oil well d ;

[0043] Step R7: According to the reservoir capacity prediction, set the optimal threshold value P of the bottom hole flow pressure drop rate max , and adjust the nozzle diameter D 油嘴 and the operating frequency f of the submersible motor, so that 0.8P max ≤P d ≤1.2P max .

[0044] Further, in step R7,

[0045] If P d >5P max , lower the nozzle diameter D 油嘴 ;

[0046] If 1.2P max ≤P d ≤5P max , lower the operating frequency f;

[0047] If P d <0.8P max , increase the operating frequency f.

[0048] Further, the step R6 comprises:

[0049] Step R6.1, obtain the middle depth H2 of the shale oil well reservoir and calculate the bottom flow pressure P of the shale oil well 流 ;

[0050] P 流 =P 套 +P 吸 +ρ 混 g(H2-H1)

[0051] Where: H1 is the depth of the pump suction port; P 吸 is the suction pressure; P 套 is the indication of the casing pressure acquisition unit; ρ 混 is the density of shale oil well fluid; g is the acceleration of gravity;

[0052] Step R6.2: Select n days as a statistical period and calculate the bottom hole pressure drop rate P d .

[0053] The present invention has the following beneficial effects: by adopting the above scheme, sand sticking, scale sticking and gas locking phenomena of submersible electric pumps during oil production in shale oil reservoirs can be effectively avoided, multi-phase medium mixed pumping can be achieved, and effective technical means can be provided for efficient lifting of unconventional oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic diagram of the structure of the present invention;

[0055] Figure 2 It is a schematic diagram of a vertical screw conveying pump;

[0056] Figure 3 It is a schematic diagram of a single screw conveying pump;

[0057] Figure 4 It is a schematic diagram of the moving screw and blades;

[0058] Figure 5 It is a schematic diagram of a static screw sleeve;

[0059] Figure 6 It is a flow chart of the operation control mode in the initial stage of production;

[0060] Figure 7 It is a flow chart of the operation control mode in the middle and late stages of production;

[0061] Figure 8 It is the control schematic diagram of the device.

[0062] In the figure, 1-downhole working condition monitoring unit, 2-submersible motor, 3-protector, 4-vertical screw conveying pump, 401-upper joint, 402-bearing sleeve, 403-housing, 404-pressing mechanism, 405-adjusting spacer, 406-static screw sleeve, 407-transmission shaft, 408-moving screw, 409-spiral blade, 410-lower end joint, 411-spline sleeve, 414-filter, 415-liquid inlet, 416-protective cap, 5-pressure head, 6-production tubing, 7-cable, 8-wellhead and data acquisition unit, 801-casing pressure acquisition unit, 802-oil pressure and production acquisition unit, 803-nozzle regulating valve, 804-tubing manifold, 805-casing manifold, 9-wellhead, 10-high voltage cable, 11-junction box, 12-frequency control system, 13-frequency step-up transformer, 14-step-down transformer. DETAILED DESCRIPTION

[0063] The present invention will be further described below in conjunction with the accompanying drawings:

[0064] Depend on Figures 1 to 5As shown, a spiral conveying multiphase flow device for shale oil wells includes a wellhead 9, a pressure head 5 is connected to the bottom of the wellhead 9 through an oil pipe 6, the lower end of the pressure head 5 is connected to a vertical spiral conveying pump 4, the bottom of the vertical spiral conveying pump 4 is connected to a protector 3, the lower end of the protector 3 is connected to a submersible motor 2, and the submersible motor 2 is a permanent magnet synchronous motor. The device also includes a downhole working condition monitoring unit and a ground data acquisition unit 8, the downhole working condition monitoring unit is used to obtain the inlet pressure and outlet pressure of the vertical spiral conveying pump 4, the motor temperature and well fluid temperature of the permanent magnet synchronous motor 2, the X / Y / Z axial vibration, current leakage and insulation resistance of the spiral conveying multiphase flow device. The downhole working condition monitoring unit includes a multi-parameter sensor 1 and a cable 7, the multi-parameter sensor 1 is located at the bottom of the submersible motor 2, and the multi-parameter sensor 1 is connected to the ground data acquisition unit 8 through the cable 7. The surface data acquisition unit 8 includes a casing pressure acquisition unit 801 and an oil pressure and production acquisition unit 802, wherein the casing pressure acquisition unit 801 is connected to the casing manifold 805 for collecting casing parameters, and the oil pressure and production acquisition unit 802 is connected to the oil pipe manifold 804 for collecting oil pipe parameters. The oil pipe manifold 804 is also provided with an oil nozzle regulating valve 803, and the operating frequency of the submersible motor 2 can be adjusted by adjusting the oil nozzle regulating valve 803. The device also includes a high-voltage cable 10, one end of which is connected to the downhole cable 7, and the other end is connected to the frequency conversion control system 12 through the junction box 11, and the frequency conversion control system 12 is respectively connected to the frequency conversion step-up transformer 13 and the step-down transformer 14. The high-voltage cable 10 has a withstand voltage of not less than 3000V and a temperature resistance of not less than 150°C; the frequency conversion control system 12 is adapted to operate in a wide frequency range of 30 to 150Hz; the step-up transformer 13 has not less than seven gears and can cover a voltage range of 2500 to 3100V with an interval of 100V; the step-down transformer 14 transmits a voltage of 380V and has a capacity of not less than 200kVA.

[0065] The vertical screw delivery pump 4 is formed by connecting several sections of single screw delivery pumps up and down. The multiple sections are connected in series to improve the delivery head of multiphase flow well fluid in shale oil wells. The single screw delivery pump includes an upper joint 401 and a lower joint 410, and the housing 403 is connected between the two. The upper joint 401 and the lower joint 410 are respectively provided with bearing sleeves 402, and the bearing sleeves 402 are supported at both ends of the transmission shaft 407 through bearings. A moving screw 408 is provided on the outside of the middle section of the transmission shaft 407, and a spiral blade 409 is provided on the outside of the moving screw 408. An adjustment sleeve 405 is provided on the outside of the upper end of the transmission shaft 407, and the upper end of the adjustment sleeve 405 is tightened by a clamping mechanism 404 to ensure axial fixation. A static screw sleeve 406 is inlaid on the inner wall of the housing 403, and a spiral ring groove with a rotation direction opposite to that of the spiral blade 409 is provided on the inner wall of the static screw sleeve 406. The moving screw 408 and the spiral blade 409 are located inside the static screw sleeve 406. The moving screw 408 is the main flow-through component of the device. Under the action of the power drive system, it plays a role in increasing the energy and pressure of the shale oil multiphase flow.

[0066] The upper joint 401 of the first-section single-body screw pump is connected to the pressure head 5 by bolts, and the lower joint 410 of the first-section single-body screw pump is connected to the upper joint 401 of the second-section single-body screw pump by bolts. At the same time, the transmission shafts 407 of the two adjacent pumps are connected by spline sleeves 411. The outer surface of the lower joint 410 of the lowermost single-body screw pump is provided with a well liquid filter 414 to prevent large-diameter sand or foreign matter from entering the pump; the side wall of the lower joint 410 is provided with a well liquid inlet 515, and the mixed liquid enters the vertical screw pump 4 through the inlet 515; the lower end of the lower joint 410 is connected to the protective cap 416 by bolts.

[0067] The shaft diameter d of the movable screw 408 is determined by the following steps:

[0068] Step S1, obtaining multiphase flow liquid density ρ, design flow rate Q, head H and rotation speed n;

[0069] Step S2: Calculate the power N of the moving screw shaft C :

[0070]

[0071] Where: N is the initial value of power;

[0072] N C =1.2N (2)

[0073] Where: 1.2 is the safety factor;

[0074] Step S3: Calculate the torque M of the moving screw shaft n :

[0075]

[0076] Step S4, calculate the shaft diameter d of the movable screw:

[0077]

[0078] Where: [τ] is the allowable shear stress, which is determined by the material of the movable screw shaft. When the movable screw shaft is made of Monel K500, the allowable shear stress [τ] is 700×10 5 N / m 2 , the moving screw shaft diameter d = 0.02379m, the moving screw shaft diameter d = 24mm, and the preferred length L = 330mm.

[0079] The spiral blade 409 has a positive spiral direction, a number of heads, and an extended shape of a three-dimensional spiral line. Its characteristic equation is expressed as follows:

[0080] X(t) = rcos(t);

[0081] Y(t) = rsin(t);

[0082] Z(t)=Pt / 2π. (5)

[0083] Wherein: t is the parameter value, the starting value of the helix is ​​t=0, and the ending value is t=12π; r is the radius of the helix; P is the lead of the helix; X(t), Y(t) and Z(t) are respectively expressed as the expressions of the X-axis, Y-axis and Z-axis in the three-dimensional coordinate system.

[0084] For the vertical screw conveying pump used for the casing with a diameter of Φ1=115mm, r=16mm, P=55mm are preferred; the spiral blade thickness σ=1.5mm is preferred, and the outer diameter of the spiral blade 409 is D=2.5d=60mm; the front and back surfaces of the spiral blade 409 are coated with Teflon coating to prevent surface scaling from affecting the conveying performance; in order to broaden the stable displacement operating range of the vertical screw conveying pump 4 and improve the pumping efficiency, the spiral rise angle ψ is in the range of 15° to 20°.

[0085] The number of spiral grooves of the static screw sleeve 406 is the same as that of the spiral blade 409, the cross-sectional shape of the spiral groove is trapezoidal, and the tooth angle β is 10°-15°; the spiral groove width S is preferably w =5mm, spiral groove depth S h =9mm, preferably the effective length L1 of the static screw sleeve 406 is =408mm.

[0086] The maximum outer diameter D1 and the nominal inner diameter d1 of the static screw sleeve 406 can be determined by the following steps:

[0087] Step T1, obtaining the diameter of the shale oil well casing Φ1=115 mm. In order to make the device have a certain passability, the maximum projection diameter of the vertical screw conveying pump 4 Φ2≤112 mm;

[0088] Step T2, considering the size of the submersible cable and the fixture, the design may be 387 series, that is, the maximum outer diameter D1 of the static screw sleeve 406 is 89 mm;

[0089] Step T3, preferably the clearance c between the moving screw 408 and the stationary screw sleeve 406 is 0.2 mm, the outer diameter D of the spiral blade of the moving screw 408 is 60 mm, and the nominal diameter d1 of the stationary screw sleeve 406 is 60.4 mm.

[0090] The spiral blades 409 on the moving screw 408 and the spiral annular grooves of the stationary screw sleeve 406 together form a multiphase flow medium flow channel. Driven by the permanent magnet synchronous submersible motor 2, the spiral blades 409 rotate in the opposite direction of their own spiral direction to form a pumping pressure for conveying the multiphase flow medium.

[0091] An operation control method for a spiral multiphase flow device for shale oil wells is provided. The method is divided into an operation control method in the initial stage of production and an operation control method in the middle and late stages of production. Generally speaking, the goal in the initial stage of production is to keep the dynamic liquid level of the spiral multiphase flow device in the optimal fluctuation range; in the middle and late stages of production, the frequency parameter adjustment and the nozzle parameter adjustment are combined to achieve the optimal operation efficiency of the spiral multiphase flow device. Specifically, the following steps are included:

[0092] Step R1: Obtain the daily liquid production Q of the shale oil downhole pump 自 , Q 自 1.5 times of the daily discharge volume Q of the screw conveying multiphase flow device at the initial stage of production 实 .

[0093] Step R2: Obtain the hydraulic characteristic curve of the spiral conveying multiphase flow device and determine the daily liquid production Q 实 The corresponding operating frequency f. Usually, the device is started at a low frequency of 35Hz, and the step length is adjusted in 1-2Hz, and the adjustment frequency is 1 time / 2min, gradually increasing to the initial target frequency f.

[0094] Step R3: After the preset electric pump well runs stably, the dynamic liquid level H of the current spiral conveying multiphase flow device is calculated by the downhole multi-parameter sensor. i ,include:

[0095] Step R3.1: Collect shale oil density ρ 页 and the water content of the well fluid ω, calculate the density ρ of the shale oil well fluid 混 ;

[0096] ρ 混 =ρ 水 ω+ρ 页(1-ω) (6)

[0097] Where: 页 is the density of shale oil; 水 is the density of water; ω is the water content of the well fluid.

[0098] Step R3.2: Collect the casing pressure collection unit reading P 套 , Multi-parameter sensor collects the suction port pressure P 吸 and the depth H1 at the pump suction port, calculate the dynamic liquid level H i ;

[0099] H i =H1-(P 吸 -P 套 )×g / ρ 混 (7)

[0100] Where: H1 is the depth of the pump suction port; P 吸 is the suction pressure; P 套 is the indication of the casing pressure collection unit; ρ 混 is the density of shale oil well fluid; g is the acceleration due to gravity.

[0101] Step R4: preset the optimal dynamic liquid level range H according to the well conditions min ~H max , generally 300m-500m; adjust the operating frequency f of the spiral conveying multiphase flow device so that H min ≤H i ≤H max ,at this time,

[0102] If H i >H max , then the frequency conversion control system is used to reduce the operating frequency f, with Δf as the frequency adjustment step, Δf is usually 2Hz, and it runs for 1h every time it is reduced by 2Hz; after the dynamic liquid level is stable, calculate the depth H at the pump suction port i , wait for H min ≤H i ≤H max When , determine the target frequency f1, and run at the target frequency f1;

[0103] If H i <H min , the frequency conversion control system is used to increase the operating frequency f, with Δf as the frequency adjustment step, Δf is also 2Hz, and the operation is performed for 1h every time the 2Hz increase is made; after the dynamic liquid level is stable, the depth H at the pump suction port is calculated i , wait for H min ≤H i ≤H max When the target frequency f2 is determined, the liquid level range H is moved at the target frequency f min ~Hmax2 run.

[0104] Step R5, dynamic liquid level H i Keep in range H min ~H max After that, take n days as a statistical period, adjust the step frequency once, and repeat steps R3 and R4.

[0105] The initial production capacity of shale oil wells is large, the dynamic liquid level is high, and the oil content is low. The above steps are the operation control mode established in the early stage of the screw conveying multiphase flow device to achieve rapid reduction of water content and early oil and gas. The flowchart of the operation control process in the early stage of production is as follows: Figure 6 shown.

[0106] In the middle and late stages of production, it includes:

[0107] Step R6: Calculate the bottom hole flow pressure drop rate P of the shale oil well d ,include,

[0108] Step R6.1, obtain the middle depth H2 of the shale oil well reservoir and calculate the bottom flow pressure P of the shale oil well 流 ;

[0109] P 流 =P 套 +P 吸 +ρ 混 g(H2-H1) (8)

[0110] Where: H1 is the depth of the pump suction port; P 吸 is the suction pressure; P 套 is the indication of the casing pressure collection unit; ρ 混 is the density of shale oil well fluid; g is the acceleration of gravity;

[0111] Step R6.2: Select n days as a statistical period and calculate the bottom hole pressure drop rate P d ,

[0112] P d =(P n -P1) / n, (9)

[0113] Where P n is the bottom flow pressure of the nth well; P1 is the bottom flow pressure of the 1st well.

[0114] Step R7: According to the reservoir capacity prediction, set the optimal threshold value P of the bottom hole flow pressure drop rate max , and adjust the nozzle diameter D 油嘴 and the operating frequency f of the submersible motor, so that 0.8P max ≤P d ≤1.2P max .

[0115] If P d >5P max At this time, the pressure drop is fast, which is easy to produce intermittent flow. In this case, the nozzle diameter D is reduced. 油嘴 To adjust the pump displacement, set the nozzle adjustment step ΔD 油嘴 , decreases by 1mm every 2h, and dynamically calculates the flow pressure drop rate P in real time d , up to 0.8P max ≤P d ≤1.2P max .

[0116] If 1.2P max ≤P d ≤5P max The pump displacement is adjusted by lowering the operating frequency f, with Δf as the frequency adjustment step, Δf is 2Hz, and the pump is operated for 1h every time the operating frequency is reduced by 2Hz, and the flow pressure drop rate P is calculated dynamically in real time. d , up to 0.8P max ≤P d ≤1.2P max .

[0117] If P d <0.8P max , the pressure drop is slow, the daily liquid production is low, and the production capacity is affected. The pump displacement is adjusted by increasing the operating frequency f, with Δf as the frequency adjustment step, Δf is also 2Hz, and the operation is increased by 2Hz for 1h, and the flow pressure drop rate P is calculated in real time. d , up to 0.8P max ≤P d ≤1.2P max .

[0118] In order to give full play to the potential of shale oil layers, the above steps are combined with the bottom hole flow pressure P 流 、Daily pressure drop of bottom hole flow pressure P d And the nozzle diameter D 油嘴 , accurately adjust the spiral conveying multiphase flow device, obtain the optimal parameter operation control mode, and the operation control flow chart of the mid- and late-stage production is as follows Figure 7 shown.

[0119] The operation control device of the spiral conveying multiphase flow device also includes (such as Figure 8 ): Current harmonic suppression unit, installed in the control processing center, used to optimize the output waveform of the frequency conversion control system 9 to make it close to a sine wave and reduce high-order harmonic components;

[0120] The downhole working condition monitoring unit is installed at the tail end of the permanent magnet synchronous submersible motor 2, and is used to obtain the inlet pressure and outlet pressure of the vertical screw conveying pump 4, the motor temperature and well fluid temperature of the submersible motor 2, and the X / Y / Z axial vibration, current leakage and insulation resistance of the screw conveying multiphase flow device;

[0121] The surface data acquisition unit 8 is installed on the wellhead 9 manifold and is used to monitor and collect casing pressure, oil pressure, temperature and production data.

[0122] The dynamic liquid level determination unit calculates the dynamic liquid level depth periodically based on the collected and processed data, and determines the frequency to be executed by the parameter adjustment method. The determination program is built into the control processing center;

[0123] The flow pressure drop determination unit calculates the bottom hole flow pressure drop periodically based on the collected and processed data, and determines the execution frequency and nozzle size by the parameter adjustment method. The determination program is built into the control processing center;

[0124] Fault self-diagnosis unit: based on the collected and processed data, determine the abnormal operating conditions according to the fault value and start the fault handling procedure;

[0125] On-site production application control panel: installed on the frequency conversion control system 9, used for parameter setting, operation data display, start / stop, fault / reset.

Claims

1. A spiral multiphase flow conveying device for a shale oil well, comprising a wellhead (9), characterized in that: The wellhead (9) is connected to a vertical screw conveying pump (4) via an oil pipe (6), and the bottom of the vertical screw conveying pump (4) is connected to a submersible motor (2); the wellhead (9) also includes a downhole operating condition monitoring unit and a surface data acquisition unit (8), wherein the downhole operating condition monitoring unit includes a multi-parameter sensor (1) located at the bottom of the submersible motor (2), and the multi-parameter sensor (1) is connected to the surface data acquisition unit (8) via a cable (7).

2. The spiral conveying multiphase flow device for shale oil wells according to claim 1, characterized in that: The vertical screw conveying pump (4) is formed by connecting a plurality of single-body screw conveying pumps, wherein the single-body screw conveying pump comprises an upper joint (401) and a lower joint (410), wherein a housing (403) is connected between the upper joint and the lower joint. A moving screw (408) is arranged inside the housing (403), and a spiral blade (409) is arranged outside the moving screw (408). A stationary screw sleeve (406) is inlaid on the inner wall of the shell (403), and a spiral annular groove having a rotation direction opposite to that of the spiral blade (409) is provided on the inner wall of the stationary screw sleeve (406), and the number of the spiral annular grooves is the same as that of the spiral blade (409). The movable screw (408) and the spiral blade (409) are located inside the stationary screw sleeve (406).

3. The spiral conveying multiphase flow device for shale oil wells according to claim 2, characterized in that: A well fluid filter screen (414) is provided on the outer surface of the lower joint (410) of the lowermost single screw conveying pump in the vertical screw conveying pump (4), and a liquid inlet (415) is provided on the side wall of the lower joint (410), through which the mixed liquid enters the vertical screw conveying pump (4).

4. The spiral conveying multiphase flow device for shale oil wells according to claim 3 is characterized in that: The shaft diameter d of the movable screw (408) is determined by the following steps: Step S1, obtaining multiphase flow liquid density ρ, design flow rate Q, head H and rotation speed n; Step S2: Calculate the power N of the moving screw shaft C : Where: N is the initial value of power; η is efficiency; <h2 style=";text-align:left;direction:ltr">N<h2 style=";text-align:left;direction:ltr"> C <h2 style=";text-align:left;direction:ltr"> <1.2N Where: 1.2 is the safety factor; Step S3: Calculate the torque M of the moving screw shaft n : Step S4, calculate the shaft diameter d of the movable screw: Where: [τ] is the allowable shear stress.

5. The spiral conveying multiphase flow device for shale oil wells according to claims 1-4, characterized in that include: A current harmonic suppression unit is used to optimize the output waveform of the frequency conversion control system (9) to make it close to a sine wave and reduce high-order harmonic components; An underground working condition monitoring unit, used to obtain the inlet pressure and outlet pressure of the vertical screw conveying pump (4), the motor temperature and well fluid temperature of the submersible motor (2), and the X / Y / Z axial vibration, current leakage and insulation resistance of the screw conveying multiphase flow device; A surface data acquisition unit (8), used for monitoring and collecting casing pressure, oil pressure, temperature and production data; The dynamic liquid level determination unit calculates the dynamic liquid level depth periodically based on the collected and processed data, and determines the frequency to be executed by the parameter adjustment method. The determination program is built into the control processing center; The flow pressure drop determination unit calculates the bottom hole flow pressure drop periodically based on the collected and processed data, and determines the execution frequency and nozzle size by the parameter adjustment method. The determination program is built into the control processing center; Fault self-diagnosis unit: based on the collected and processed data, determine the abnormal operating conditions according to the fault value and start the fault handling procedure; On-site production application control panel: installed on the frequency conversion control system (9), used for parameter setting, operation data display, start / stop, fault / reset.

6. An operation control method for a spiral multiphase flow conveying device for shale oil wells, characterized in that The following steps are involved: Step R1: Obtain the daily liquid production Q of the spiral conveying multiphase flow device at the initial stage of production 实 ; Step R2: Obtain the hydraulic characteristic curve of the spiral conveying multiphase flow device and determine the daily liquid production Q 实 The corresponding operating frequency f; Step R3: Calculate the dynamic liquid level H of the current spiral conveying multiphase flow device i ; Step R4: Preset the optimal dynamic liquid level range H min ~H max , adjust the operating frequency f of the spiral conveying multiphase flow device so that H min ≤H i ≤H max ; Step R5, taking n days as a statistical period, as a step frequency adjustment, repeating steps R3 and R4.

7. The operation control method of the spiral conveying multiphase flow device for shale oil wells according to claim 6 is characterized in that: In step R3, H i =H1-(P 吸 -P 套 )g / p 混 Where: H1 is the depth of the pump suction port; P 吸 is the suction pressure; P 套 is the indication of the casing pressure collection unit; ρ 混 is the density of shale oil well fluid; g is the acceleration of gravity; The shale oil well fluid density ρ 混 for r 混 =ρ 水 oh+r 页 (1-h) Where: 页 is the density of shale oil; 水 is the density of water; ω is the water content of the well fluid.

8. The operation control method of the spiral conveying multiphase flow device for shale oil wells according to claim 7 is characterized in that: In step R4, if H i >H max , then reduce the operating frequency f, and use Δf as the frequency adjustment step. After the dynamic liquid surface is stable, calculate the depth H at the pump suction port i , wait for H min ≤H i ≤H max When , determine the target frequency f1, and run at the target frequency f1; If H i <H min , then increase the operating frequency f, and use Δf as the frequency adjustment step. After the dynamic liquid surface is stable, calculate the depth H at the pump suction port i , wait for H min ≤H i ≤H max When the target frequency f2 is determined, the inverter operates at the target frequency f2.

9. The operation control method of the spiral conveying multiphase flow device for shale oil wells according to claim 8, characterized in that Also includes: Step R6: Calculate the bottom hole flow pressure drop rate P of the shale oil well d ; Step R7: According to the reservoir capacity prediction, set the optimal threshold value P of the bottom hole flow pressure drop rate max , and adjust the nozzle diameter D 油嘴 and the operating frequency f of the submersible motor, so that 0.8P max ≤P d ≤1.2P max .

10. The operation control method of the spiral conveying multiphase flow device for shale oil wells according to claim 9, characterized in that: In step R7, If P d >5P max , lower the nozzle diameter D 油嘴 ; If 1.2P max ≤P d ≤5P max , lower the operating frequency f; If P d <0.8P max , increase the operating frequency f; and / or, The step R6 comprises: Step R6.1, obtain the middle depth H2 of the shale oil well reservoir and calculate the bottom flow pressure P of the shale oil well 流 ; P 流 =P 套 +P 吸 +r 混 g(H2-H1) Where: H1 is the depth of the pump suction port; P 吸 is the suction pressure; P 套 is the indication of the casing pressure collection unit; ρ 混 is the density of shale oil well fluid; g is the acceleration of gravity; Step R6.2: Select n days as a statistical period and calculate the bottom hole pressure drop rate P d .

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