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

Abstract

A spiral conveying multiphase flow device and operation control method for shale oil wells. The device mainly solves the problem of sand jamming, scale jamming, and gas lock occurring during the oil production process of existing submersible electric pumps. The device is characterized in that: a vertical spiral conveying pump (4) is connected to the bottom of the wellhead (9) through an oil pipe (6), and the bottom of the vertical spiral conveying pump (4) is connected to a submersible motor (2); the device also includes a downhole working condition monitoring unit and a ground data acquisition unit (8), wherein the downhole working 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 ground data acquisition unit (8) through a cable (7). The method avoids the occurrence of sand jamming, scale jamming, and gas lock occurring during the oil production process of the submersible electric pump in shale oil reservoirs, realizes mixed extraction of multiphase media, improves the operating efficiency of the unit, and ensures continuous production of the oil well.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, in particular to a spiral multiphase flow conveying device for shale oil wells and an operation control method thereof. 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 application, 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 option is to inspect the pump and replace the lifting equipment, which cannot guarantee continuous production of shale oil wells. Summary of the Invention

[0003] In order to overcome the problems of sand sticking, scale sticking and gas lock occurring easily 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 by submersible electric pumps, realizes mixed pumping of multiphase media, improves the operating efficiency 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 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 working condition monitoring unit and a ground data acquisition unit, the downhole working 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 composed of several sections of single screw conveying pumps connected together. The single screw conveying pump includes an upper joint and a lower joint, which are connected to a shell. A moving screw is arranged inside the shell, and spiral blades are arranged outside the moving screw.

[0006] A static screw sleeve is embedded on the inner wall of the shell. A spiral ring groove is arranged on the inner wall of the static screw sleeve in the opposite direction of the spiral blade. The number of the spiral ring grooves is the same as that of the spiral blade. The dynamic screw and the spiral blade are located inside the static 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 the multiphase flow liquid density ρ, design flow rate Q, head H and 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 and outlet pressures of the vertical screw conveying pump, the motor temperature of the submersible motor and the well fluid temperature, and the 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. The frequency to be executed is determined 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. The frequency and nozzle size to be executed are determined by the parameter adjustment method. The determination program is built into the control and processing center.

[0025] Fault self-diagnosis unit: Based on the collected and processed data, it determines the abnormal operating condition according to the fault value and starts 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] A method for controlling the operation of a spiral multiphase flow conveying device for a shale oil well comprises the following steps:

[0028] Step R1: Obtain the daily liquid production Q of the spiral multiphase flow device at the initial stage of operation 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: Take n days as a statistical period and adjust the step frequency once, and repeat 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 port 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: ρ 页 is the density of shale oil; ρ 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 port.i , 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 and 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 productivity forecast, 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 includes,

[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 port 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-mentioned 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 structural schematic diagram 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 the static screw sleeve;

[0059] Figure 6 This 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 principle 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-drive 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 multiphase flow device for shale oil wells includes a wellhead 9, below which is connected a pressure head 5 via an oil pipe 6. The lower end of the pressure head 5 is connected to a vertical spiral pump 4. The bottom of the vertical spiral pump 4 is connected to a protector 3, and the lower end of the protector 3 is connected to a submersible motor 2, which is a permanent magnet synchronous motor. The device also includes a downhole operating condition monitoring unit and a surface data acquisition unit 8. The downhole operating condition monitoring unit is used to monitor the inlet and outlet pressures of the vertical spiral pump 4, the motor temperature of the permanent magnet synchronous motor 2 and the well fluid temperature, the X / Y / Z axial vibration of the spiral multiphase flow device, current loss, and insulation resistance. The downhole operating 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 is connected to the surface data acquisition unit 8 via 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. The casing pressure acquisition unit 801 is connected to a casing manifold 805 for collecting casing parameters, while the oil pressure and production acquisition unit 802 is connected to an oil pipe manifold 804 for collecting oil pipe parameters. The oil pipe manifold 804 is also equipped with a nozzle regulating valve 803, which can be adjusted to adjust the operating frequency of the submersible motor 2. 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 a frequency conversion control system 12 via a junction box 11. The frequency conversion control system 12 is connected to a variable frequency step-up transformer 13 and a step-down transformer 14, respectively. The high-voltage cable 10 has a withstand voltage of no less than 3000V and a temperature resistance of no 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 no 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 no less than 200kVA.

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

[0066] The upper joint 401 of the first-section single-unit screw pump is bolted to the pressure head 5. The lower joint 410 of the first-section single-unit screw pump is bolted to the upper joint 401 of the second-section single-unit screw pump. The drive shafts 407 of the two adjacent pumps are connected by a splined sleeve 411. A well fluid filter 414 is installed on the outer surface of the lower joint 410 of the lowest-end single-unit screw pump to prevent large-diameter sand particles or foreign matter from entering the pump. A well fluid inlet 515 is opened on the side wall of the lower joint 410, through which the mixed liquid enters the vertical screw pump 4. The lower end of the lower joint 410 is bolted to a protective cap 416.

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

[0068] Step S1, obtaining the multiphase flow liquid density ρ, design flow rate Q, head H and 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 a three-dimensional spiral shape. Its characteristic equation is expressed as follows:

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

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

[0082] Z(t)=Pt / 2π. (5)

[0083] Where 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 the expressions of the X-axis, Y-axis, and Z-axis in the three-dimensional coordinate system, respectively.

[0084] For the vertical screw conveying pump used for the casing with a diameter of Φ1 = 115 mm, r = 16 mm and P = 55 mm are preferred; the spiral blade thickness σ = 1.5 mm, and the outer diameter of the spiral blade 409 is D = 2.5d = 60 mm; 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 ring 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 preferred width of the spiral ring groove is S 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: Obtain the shale oil well casing diameter Φ1 = 115 mm. To ensure that the device has a certain passability, the maximum projected diameter Φ2 of the vertical screw pump 4 is ≤ 112 mm.

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

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

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

[0091] A method for controlling the operation of a spiral multiphase flow device for shale oil wells is described. The method is divided into an initial operation control method and a mid-to-late production operation control method. Generally speaking, in the initial production period, the goal is to keep the dynamic liquid level of the spiral multiphase flow device within an optimal fluctuation range. In the mid-to-late production period, frequency and nozzle parameter adjustments are combined to optimize the operating efficiency of the spiral multiphase flow device. Specifically, the method includes the following steps:

[0092] Step R1: Obtain the daily fluid 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 in 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 adjustment step is 1 to 2Hz, and the adjustment frequency is 1 time / 2 minutes, gradually increasing to the initial target frequency f.

[0094] Step R3: After the preset electric pump well is running stably, the dynamic liquid level H of the current spiral 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 well fluid water content ω, calculate the shale oil well fluid density ρ 混 ;

[0096] ρ 混 =ρ 水 ω+ρ 页(1-ω) (6)

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

[0098] Step R3.2: Collect the casing pressure data P 套 , Multi-parameter sensor collects the suction port pressure P 吸 and the depth H1 at the pump inlet, 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 port 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 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 reduce the operating frequency f through the frequency conversion control system, with Δf as the frequency adjustment step, Δf is usually 2Hz, and run 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 , then the operating frequency f is increased by the frequency conversion control system, with Δf as the frequency adjustment step, Δf is also 2Hz, and the operation is carried out for 1h every time the 2Hz is increased; 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 stride 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 water reduction and early oil and gas discovery. The operation control flow chart of the initial 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 port 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;

[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 well on the nth day; P1 is the bottom flow pressure of the well on the 1st day.

[0114] Step R7: According to the reservoir productivity forecast, 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 drops quickly and intermittent flow is likely to occur. In this case, the nozzle diameter D is lowered. 油嘴 To adjust the pump displacement, set the nozzle adjustment step ΔD 油嘴 , decrease by 1mm every 2 hours, and calculate the pressure drop rate P dynamically 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. Every time it increases 2Hz, it runs for 1h, and the flow pressure drop rate P is dynamically 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 layer, 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 to obtain the optimal parameter operation control mode, and the operation control flow chart in the middle and late stages of 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] Downhole working condition monitoring unit, installed at the tail end of permanent magnet synchronous submersible motor 2, used to obtain the inlet and outlet pressures of the vertical screw conveying pump 4, the motor temperature and well fluid temperature of submersible motor 2, 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. The frequency to be executed is determined 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. The frequency and nozzle size to be executed are determined by the parameter adjustment method. The determination program is built into the control and processing center.

[0124] Fault self-diagnosis unit: Based on the collected and processed data, it determines the abnormal operating condition according to the fault value and starts 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. An operation control method for a spiral multiphase flow device for shale oil wells, characterized in that The following steps are involved: In the initial stage of production, steps R1 to R5 are implemented. Step R1: Obtain the daily liquid production of the spiral multiphase flow device at the initial stage of production Q 实 ; Step R2: Obtain the hydraulic characteristic curve of the spiral conveying multiphase flow device and determine the daily liquid production Q 实 Corresponding operating frequency f ; Step R3: Calculate the dynamic liquid level of the current spiral conveying multiphase flow device H i ; Step R4: Preset the optimal dynamic liquid level range H min ~ H max , adjust the operating frequency of the spiral conveying multiphase flow device f ,make H min ≤H i ≤H max ; Step R5: Take n days as a statistical period, adjust the step frequency once, and repeat steps R3 and R4; In the middle and late stages of production, implement steps R6 and R7. Step R6: Calculate the bottom hole flow pressure drop rate of shale oil well P d ; Step R7: Set the optimal threshold of the bottom hole flow pressure drop rate according to the reservoir productivity forecast P max , and adjust the nozzle diameter D 油嘴 and the operating frequency of the submersible motor f ,make 0.8P max ≤P d ≤1.2P max .

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

3. The operation control method of the spiral multiphase flow device for shale oil wells according to claim 2, characterized in that: In step R4, if H i >H max , then reduce the operating frequency f , with Δ f is the frequency adjustment step. After the dynamic liquid surface is stable, calculate the depth at the pump suction port. H i ,treat H min ≤H i ≤H max When the target frequency is determined f 1 and at the target frequency f 1 run; like H i <H min , then increase the operating frequency f , with Δ f is the frequency adjustment step. After the dynamic liquid surface is stable, calculate the depth at the pump suction port. H i ,treat H min ≤H i ≤H max When the target frequency is determined f 2 and at the target frequency f 2 run.

4. The operation control method of the spiral multiphase flow conveying device for shale oil wells according to claim 3, characterized in that: In the step R7, like P d > 5 P max , lower the nozzle diameter D 油嘴 ; like 1.2P max ≤P d ≤ 5 P max , lower the operating frequency f ; like P d <0.8P max , increase the operating frequency f .

5. The operation control method of the spiral multiphase flow conveying device for shale oil wells according to claim 3 or 4, characterized in that: The step R6 comprises, Step R6.1: Obtain the medium-depth and deep reservoir of shale oil wells H 2 , calculate the bottom flow pressure of shale oil P 流 ; P 流 =P 套 +P 吸 +ρ 混 g(H 2 -H 1 ） Where: H 1 is the depth at the pump suction port; P 吸 is the suction pressure; P 套 Indication of casing pressure collection unit; ρ 混 is the density of shale oil well fluid; g is the acceleration due to 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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