Electric submersible pump process design method applied to polymer oil well

Abstract

The invention discloses an electric submersible pump process design method applied to a polymer oil well. The electric submersible pump process design method comprises the steps that (1) design parameters are input or called; (2) selecting the pump type of a polymer-resistant pump; (3) calculating the total dynamic pressure head of the oil well; (IV) correcting a polymer-resistant pump characteristic curve; (V) determining the lift and the stage number of the polymer-resistant pump; vI, determining the pump efficiency and the shaft power of the polymer-resistant pump; (VII) performing an option of a polymer-resistant leading pump; (VIII) selecting types of a submersible motor, a protector and a cable; and (IX) well descending accessory model selection and the like. On the basis of a conventional electric submersible pump design method, a polymer-resistant pump with an optimized structure is matched, a polymer-resistant leading pump is additionally arranged, and various parameters of an electric pump unit are optimized by adopting various correction calculations for polymer-containing well fluid, so that the polymer-resistant integrated process scheme design of the electric submersible pump is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of process design of oil extraction equipment submersible electric pump unit, and particularly relates to an electric submersible pump process design method applied to a polymer oil well, namely, an electric submersible pump selection method applied to a polymer oil well. BACKGROUND

[0002] Polymer flooding is an important enhanced oil recovery technology for tertiary oil recovery, and is widely used in submersible electric pump wells in offshore oilfields. However, while the polymer enhances the oil recovery, it changes the physical parameters of the electric pump well fluid, affects the rheological properties of the produced fluid, and easily causes faults such as electric submersible pump plugging and frequent overload, thereby reducing the operating life of the electric pump well, affecting the production time and the oil well production. Therefore, the physical properties of the polymer-containing well fluid need to be fully considered in the process design of the electric submersible pump, and the conventional electric submersible pump process design method cannot meet the above requirements. SUMMARY

[0003] The application is proposed to solve the problems in the prior art, and aims to provide an electric submersible pump process design method applied to a polymer oil well.

[0004] The application is implemented by the following technical scheme:

[0005] An electric submersible pump process design method applied to a polymer oil well comprises the following steps:

[0006] (I) input or call design parameters, the design parameters including design liquid production, pump hanging depth H p , suction port pressure head p m , oil pressure conversion head p o , and other data;

[0007] (II) select the rated displacement Q according to the design liquid production, and retrieve the sample library to determine the pump type of the polymer pump;

[0008] (III) calculate the total dynamic pressure head of the oil well from the wellhead as the starting point, and the calculation formula is as follows:

[0009] H = H p + p o + F t - p m (Formula 1)

[0010] In the formula, H is the total dynamic pressure head of the oil well, m;

[0011] H p is the pump hanging depth, m;

[0012] p o is the oil pressure conversion head, m;

[0013] Ft — tubing friction loss head, m;

[0014] p m — pump suction head, m;

[0015] wherein the tubing friction loss head can be found by appending Figure 3 to the pump head.

[0016] (IV) Correcting the characteristic curve of the polymer tolerant pump

[0017] In step (IV), the characteristic curve of the polymer tolerant pump needs to be corrected in combination with the actual well conditions, and the correction method is calculated through the following process:

[0018] (i) The pump characteristic curve Q-H relationship at the rated frequency of the electric pump (ESP) obtained by the fresh water experiment (the polymer tolerant pump characteristic curve is shown in the attached Figure 4 ) is known:

[0019] H = aQ + bQ + cQ + dQ + e (Formula 2) 4 3 2

[0020] wherein H is the head, unit m; Q is the displacement, unit m 3 / d; a, b, c, d, e are known constant values;

[0021] (ii) The head correction coefficient is determined according to the polymer content for correction:

[0022] H vis = C H ·H (Formula 3)

[0023] wherein H vis is the corrected head, unit m; C H is the correction coefficient, dimensionless; H is the head before correction, unit m;

[0024] (iii) The pump characteristic curve Q-H relationship of the polymer tolerant pump after correction is obtained according to (i) and (ii) as follows: vis

[0025] H vis = aQ 4 (C H ) 4 +bQ 3 (C H ) 3 +cQ 2 (C H ) 2 +dQ(C H )+e (Formula 4) ​​​​

[0026] H vis is the corrected head, unit: m; Q is the displacement, unit: m 3 / d; C H is the correction coefficient, dimensionless; a, b, c, d, e are known constant values, dimensionless.

[0027] (Ⅴ) Determine the head and stage number of the polymer-tolerant pump

[0028] (i) Head: according to the total dynamic pressure head H of the pump, the corrected head H is obtained by comparing the corrected characteristic curve of the polymer-tolerant pump vis

[0029] (ii) Stage number: the stage number N of the polymer-tolerant pump is calculated according to formula 5

[0030] N = H vis / H 单级 (Formula 5)

[0031] In the formula: N is the stage number of the polymer-tolerant pump, dimensionless; H vis is the corrected head, unit: m; H 单级 is the single-stage head, unit: m.

[0032] (VI) Determine the pump efficiency and shaft power of the polymer-tolerant pump

[0033] (i) Query the polymer-tolerant pump characteristic curve to determine the pump efficiency η of the polymer-tolerant pump

[0034] (ii) Calculate the shaft power P of the electric pump 轴 :

[0035]

[0036] In the formula: ρ is the density of the well fluid, unit: g / cm 3 ; η is the pump efficiency of the polymer-tolerant pump, dimensionless; H is the head, unit: m; Q is the displacement, unit: m 3 / d.

[0037] (VII) Select the model of the polymer-tolerant front pump: select the polymer-tolerant front pump according to the designed displacement, the purpose is to pass the polymer-containing well fluid through the polymer-tolerant front pump to enter the polymer-tolerant pump, the structure is shown in the attached Figure 5

[0038] (VIII) Select the submersible motor, protector and cable

[0039] (i) The motor power is calculated by the following formula:

[0040] P 电 = k (P 轴 + P 前 + P 保 ) (Formula 7) ​

[0041] in

[0042] Where: P 电 is the power of the submersible motor, in kW; P 轴 is the power of the polymer-resistant pump, in kW; P 前 is the power of the poly-resistant pilot pump, in kW; P 保 is the power of the protector in kW; k is the safety margin, dimensionless.

[0043] (ⅱ) Protector selection

[0044] The protector series is matched with the motor, and the protector breathing capacity selects double capsules in series with the sedimentation cavity and is equipped with a high-load thrust bearing.

[0045] (ⅲ) Cable selection

[0046] The cable type is selected according to the rated current of the motor:

[0047] Recommended values ​​for maximum current carrying capacity. It is recommended to leave appropriate margin in actual application:

[0048] If the motor rated current is less than 110A, select AWG 1#;

[0049] If the motor rated current is less than 95A, select AWG2#;

[0050] If the motor rated current is less than 75A, select AWG4#;

[0051] If the motor rated current is less than 65A, select AWG 5#;

[0052] If the motor rated current is less than 55A, select AWG 6#.

[0053] ② Voltage level: Match according to the rated voltage of the motor.

[0054] General voltage levels: 3kV, 5kV, 6kV.

[0055] (Ⅸ) Selection of downhole accessories

[0056] (i) Configure oil drain valve and check valve according to production requirements: Configure oil drain valve and check valve, as shown in the attached Figure 6 As shown, the check valve prevents the polymer from falling back when the pump is stopped and causing the pump flow channel to be blocked;

[0057] (ii) Cable guards and centralizers: A cable guard is provided every 9.6 m according to the cable length. The model is adapted to the oil pipe and the unit, and the centralizer is adapted to the inner diameter of the casing and the outer diameter of the unit.

[0058] The beneficial effects of the present invention are:

[0059] The application provides a method for selecting an electric submersible pump applied to a polymer oil well. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 is a flow chart of the application;

[0061] Figure 2 is a schematic diagram of a polymer-resistant pump impeller and guide shell in Example 1 of the application (a is the impeller; b is the guide shell);

[0062] Figure 3 is an API tubing friction loss diagram in Example 1 of the application;

[0063] Figure 4 is a polymer-resistant pump characteristic curve diagram in Example 1 of the application;

[0064] Figure 5 is a schematic diagram of a polymer-resistant front guide pump in Example 1 of the application;

[0065] Figure 6 is a check valve diagram in Example 1 of the application;

[0066] Figure 7 is a polymer-resistant integrated design application well operation curve diagram in Example 1 of the application.

[0067] For those skilled in the art, other related drawings can be obtained from the above drawings without creative labor. DETAILED DESCRIPTION

[0068] In order for those skilled in the art to better understand the technical solutions of the application, the technical solutions of the application will be further described below by combining the drawings in the specification and through specific embodiments.

[0069] Example 1

[0070] A polymer oil well electric submersible pump process design method, as shown in Figure 1 , includes the following steps:

[0071] (I) Input or call design parameters:

[0072] Hash LD10-1-C27 Designing for fluid production 400 m 3 / d]] Pump hang depth H p ]]> 1370m suction port pressure head p m ]]> 685m Hydraulic pressure equivalent head p o ]]> 200m

[0073] (II) According to the design liquid production, the rated displacement Q = 400 m 3 / d is selected, and the sample library determines that the pump type of the polymer-resistant pump is BG4000;

[0074] Compared with the conventional ESP, the polymer-resistant pump adopts a mixed-phase flow channel design to realize polymer lifting and pressure boosting, and is more suitable for polymer well conditions. The impeller and guide shell structure of the polymer-resistant pump selected in the embodiment is shown in the attached drawings Figure 2 ;

[0075] (III) Calculate the total dynamic pressure head of the oil well from the wellhead, and the calculation formula is as follows:

[0076] H = H p + p o + F t - p m = 1370 m + 200 m + 40.6 m - 685 m = 925.6 m

[0077] Where, the tubing friction loss pressure head can be obtained by referring to the attached Figure 3 , F t = 40.6 m

[0078] (IV) Correct the characteristic curve of the polymer-resistant pump

[0079] In step (IV), the characteristic curve of the polymer-resistant pump needs to be corrected in combination with the actual well conditions, and the correction method is calculated through the following process:

[0080] (IV-1) The pump characteristic curve Q-H relationship of BG4000 pump type at ESP rated frequency obtained by water experiment is known

[0081] H = -2 x 10 -12 Q 4 - 10 -8 Q 3 + 10 -5 Q 2 - 0.0093Q + 11

[0082] (IV-2) Correct according to the head correction coefficient determined according to the polymer content:

[0083] H vis = 1.4H

[0084] (IV-3) The corrected pump characteristic curve Q-H of the polymer-resistant pump obtained according to (IV-1) and (IV-2) is: vis

[0085] H vis = -3 x 10 -12 Q 4 - 2 x 10 -8 Q 3 + 10 -5 Q 2 - 0.013Q + 15.4

[0086] ​(V) Determine the head of the polypropylene pump, the number of stages

[0087] (V-ⅰ) Head: According to the total dynamic pressure head H of the oil well, the corrected head H is obtained by comparing the polypropylene pump correction characteristic curve vis = 1295.84 m, the actual production is 1300 m.

[0088] (V-ⅱ) Stage: The number of stages N of the polypropylene pump is calculated according to formula 5

[0089] N = H vis / H 单级 = 1300 / 8.2 = 158 stages

[0090] (VI) Determine the pump efficiency of the polypropylene pump and the shaft power

[0091] (VI-ⅰ) Query the polypropylene pump characteristic curve to determine the pump efficiency η = 61%

[0092] (VI-ⅱ) Calculate the shaft power P of the electric pump 轴 :

[0093]

[0094] (VII) Select the type of polypropylene leading pump: According to the design displacement, the polypropylene leading pump GP-S513-400m is selected 3 / d

[0095] (VIII) Select the submersible motor, protector and cable

[0096] (VIII-ⅰ) Motor power is calculated by the following formula:

[0097] P 电 = k (P 轴 + P 前 + P 保 ) = 1.3 × (104.6 + 25 + 5) = 175 kW

[0098] (VIII-ⅱ) Protector selection

[0099] The protector series matches the motor, the protector breathing capacity selects double capsule series sinking chamber, and configures high bearing thrust bearing, the type is: BPR513BPBSL + BPBSL-HL

[0100] (VIII-ⅲ) Cable selection

[0101] The cable type is selected according to the rated current of the motor, AWG4 integrated lead sheath flat cable is selected, the type is: QYYEQ-3*20mm 2 / 150℃

[0102] (IX) Selection of downhole accessories

[0103] (IX-i) Oil drain valve: 3-1 / 2" EU; Single flow valve: 3-1 / 2" EU.

[0104] (IX-ii) Configuration cable shield: 3-1 / 2" EU-4# flat x 178 + KT90 x 5

[0105] Output resistant poly integration design as follows:

[0106]

[0107] Application effect: on May 24, 2020, the first set of resistant poly integration process scheme application well put into production, running smoothly, oil production increased by 5.8 times (20m 3 / d→116m 3 / d), see attached Figure 7 .

[0108] Applicants declare that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the present application, which can be easily thought of by any person skilled in the art, falls within the protection scope and disclosure scope of the present application.

Claims

1. A process design method for an electric submersible pump for polymer oil wells, characterized by: The following steps are involved: (I) Input or call design parameters; (II) Select the rated displacement according to the designed liquid production and search the sample library to determine the type of polymer-resistant pump; (III) Calculate the total dynamic head of the oil well with the wellhead as the starting point; (IV) Correction of the characteristic curve of the anti-agglomeration pump; (V) Determine the head and number of stages of the polymer-resistant pump; (VI) Determine the pump efficiency and shaft power of the polymer-resistant pump; (VII) Select the model of the poly-resistant pilot pump according to the designed displacement; (VIII) Select submersible motors, protectors and cables; (Ⅸ) Selection of downhole accessories.

2. The process design method for an electric submersible pump for a polymer oil well according to claim 1, characterized in that: The design parameters include designed liquid production, pump hanging depth, suction port pressure head and oil pressure converted pressure head.

3. The process design method for an electric submersible pump for a polymer oil well according to claim 1, characterized in that: The calculation formula of the total dynamic head of the oil well in step (III) is as follows: H=H p +p o +F t -p m (Formula 1) Where: H is the total dynamic pressure head of the oil well, unit is m; H p is the pump hanging depth, in m; p o is the oil pressure converted head, unit is m; F t is the oil pipe friction loss pressure head, in m, obtained from the API oil pipe friction loss chart; p m It is the pump suction pressure head, in m.

4. The process design method for an electric submersible pump for a polymer oil well according to claim 1, characterized in that: The method for correcting the characteristic curve of the polymerization-resistant pump in step (IV) specifically comprises the following steps: (i) The pump characteristic curve QH relationship at the rated frequency of the ESP is obtained based on the clean water test. The pump characteristic curve QH relationship is as follows: H = aQ 4 + bQ 3 + cQ 2 + dQ + e (Formula 2) Where: H is the head, unit is m; Q is the displacement, unit is m 3 / d; abcde are known constant values; (ii) Determine the head correction factor based on the polymer content and perform correction: H vis =C H H (Formula 3) Where: H vis is the corrected head, in m; C H is the correction coefficient, dimensionless; H is the head before correction, in meters; (iii) According to (i) and (ii), the pump characteristic curve QH after the anti-polymerization pump correction is obtained vis The relationship is: H vis =aQ 4 (C H ) 4 +bQ 3 (C H ) 3 +cQ 2 (C H ) 2 +dQ(C H )+e (Formula 4) Where: H vis is the corrected head, in m; Q is the displacement, in m 3 / d;C H is the correction coefficient, dimensionless; abcde is a known constant value, dimensionless.

5. The process design method for an electric submersible pump for a polymer oil well according to claim 1, characterized in that: The method for determining the head of the anti-agglomeration pump in step (V) is specifically as follows: the corrected head H is obtained by comparing the total dynamic pressure head H of the oil well with the correction characteristic curve of the anti-agglomeration pump. vis ; The method for determining the number of stages of the anti-agglomeration pump in step (V) is as follows: query the characteristic curve of the anti-agglomeration pump and determine the single-stage head H 单级 , the number of stages N of the polymer-resistant pump is calculated according to the following formula; N=H vis / H 单级 (Formula 5) Where: N is the number of stages of the polymer-resistant pump, dimensionless; H vis is the head after correction, in m; H 单级 It is the single-stage head, unit is m.

6. The process design method for an electric submersible pump for a polymer oil well according to claim 1, characterized in that: The method for determining the pump efficiency of the anti-agglomeration pump in step (VI) is specifically: querying the characteristic curve of the anti-agglomeration pump to determine the pump efficiency η of the anti-agglomeration pump; The method for determining the shaft power of the anti-polymer pump in step (VI) is as follows: the shaft power of the electric pump P is calculated according to the following formula: 轴 : Where: ρ is the well fluid density, unit is g / cm 3 ; η is the pump efficiency of the anti-polymer pump, dimensionless; H is the head, unit is m; Q is the displacement, unit is m 3 / d.

7. The process design method for an electric submersible pump for a polymer oil well according to claim 1, characterized in that: The method for selecting the submersible motor in step (VIII) is specifically as follows: the motor power is calculated according to the motor power calculation formula, and the submersible motor is selected based on the motor power obtained by calculation; the method for selecting the protector in step (VIII) is specifically as follows: the protector is determined according to the selected submersible motor, the protector series is matched with the submersible motor, the breathing volume of the protector selects a double capsule series sedimentation cavity, and a high-load thrust bearing is configured; the method for selecting the cable in step (VIII) is specifically as follows: the cable model is selected according to the rated current of the selected submersible motor; the voltage level is matched according to the rated voltage of the selected submersible motor.

8. The process design method for an electric submersible pump for a polymer oil well according to claim 7, characterized in that: The motor power calculation formula is: P 电 =k(P 轴 +P 前 +P 保 ) (Formula 7) Where: P 电 is the power of the submersible motor, in kW; P 轴 is the power of the polymer-resistant pump, in kW; P 前 is the power of the poly-resistant pilot pump, in kW; P 保 is the power of the protector in kW; k is the safety margin, dimensionless.

9. The process design method for an electric submersible pump for a polymer oil well according to claim 7, characterized in that: The specific selection of the cable model is: If the motor rated current is less than 110A, select AWG 1#; If the motor rated current is less than 95A, select AWG2#; If the motor rated current is less than 75A, select AWG4#; If the motor rated current is less than 65A, select AWG 5#; If the motor rated current is less than 55A, select AWG 6#.

10. The process design method for an electric submersible pump for a polymer oil well according to claim 1, characterized in that: The specific method of selecting the downhole accessories in step (IX) is as follows: (i) Configure oil drain valve and check valve according to production requirements; (ii) A cable guard is configured every 9.6m according to the cable length. The cable guard model is adapted to the oil pipe and the unit; the centralizer is adapted to the inner diameter of the casing and the outer diameter of the unit.

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