Method, system and equipment for optimizing oil pumping speed curve of oil well and storage medium

Abstract

The invention provides an oil well oil pumping speed curve optimization method, system and equipment and a storage medium, and belongs to the technical field of petroleum industry, a plunger motion curve is expressed as a trapezoidal motion curve by establishing a relational expression of pump efficiency and plunger motion speed, a plunger motion equation is expressed in a Fourier series expansion form, and the pump efficiency and the plunger motion speed are optimized. And determining constraint conditions according to oil well swabbing parameters to obtain an optimized plunger motion equation. According to the optimized oil pumping speed curve, the plunger can move at a constant speed for a long time in the up-down stroke, the good inlet and outlet instantaneous displacement can be maintained in the swabbing process, the oil well pump efficiency is improved, meanwhile, the unstable factor of sudden acceleration change of a trapezoidal motion curve is overcome, impact is effectively reduced, and motor operation is more stable.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum industry, and in particular relates to an oil well pumping speed curve optimization method, system, equipment and storage medium. Background Art

[0002] Under normal conditions, the crank of the oil pump makes uniform circular rotation, and the suspension point drives the plunger of the oil pump to perform quasi-sinusoidal motion, resulting in uneven distribution of the plunger's running speed and a large speed peak. This causes large fluctuations in the inlet and outlet pressures of the oil pump, and the upstroke cannot maintain a stable inlet flow, resulting in low efficiency of the oil pump.

[0003] The current technology for variable speed control of oil pumps only changes the speed distribution of the plunger during the pumping process by adjusting the stroke frequency through frequency conversion, but does not fundamentally change the inherent quasi-sinusoidal motion of the plunger. It cannot ensure that the oil pump can stably absorb liquid during the upstroke, nor can it achieve a high pump efficiency.

[0004] The trapezoidal speed curve is an acceleration and deceleration control strategy widely used in the field of industrial control. The acceleration remains unchanged during the speed change process, and the motor runs more smoothly. When the oil pump plunger moves using a trapezoidal curve, it has a long period of uniform motion in both the up and down strokes, and can maintain a good inlet and outlet instantaneous displacement during the pumping process. However, since the trapezoidal speed curve will overshoot at the inflection point of constant acceleration, it is easy to cause shock and vibration to the system. Summary of the invention

[0005] In view of the above problems, the present invention proposes a method and system for optimizing the oil well pumping speed curve. The optimized pumping speed curve allows the plunger to move at a constant speed for a long period of time in both the up and down strokes, and can maintain a good inlet and outlet instantaneous displacement during the pumping process, thereby improving the pumping efficiency. At the same time, it overcomes the unstable factor of the sudden acceleration change of the trapezoidal motion curve, effectively reduces the impact, and makes the motor run more smoothly.

[0006] The present invention provides a method for optimizing an oil well pumping speed curve, comprising:

[0007] According to the influence of elastic expansion and contraction of rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the volume contraction caused by surface crude oil degassing on the pump efficiency, a pump efficiency relationship is established;

[0008] The pump efficiency relationship is expressed as a function of the plunger movement speed, and a trapezoidal motion curve is obtained by expanding the function of the plunger movement speed;

[0009] Determining a plunger motion equation according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing a Fourier series expansion on a function of the plunger motion speed;

[0010] Taking the pumping parameters in the actual operation condition of the oil well as the constraint conditions, the optimal parameter solution is obtained by solving the plunger motion equation;

[0011] The optimal parameter solution is substituted into the plunger motion equation, and the optimized pumping speed curve is expressed by the plunger motion equation.

[0012] Preferably, the pump efficiency relationship is established based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, including:

[0013] Determine the influence of the elastic expansion and contraction of the rod tube on the efficiency of the oil well pump according to the plunger stroke and the polished rod stroke of the oil well pump, wherein the plunger stroke is obtained according to the polished rod stroke and the stroke loss;

[0014] The stroke loss is determined by the cross-sectional area of ​​the plunger, the cross-sectional area of ​​the sucker rod, the cross-sectional area of ​​the sucker pipe, the total length of the sucker rod string, the liquid density, the dynamic liquid level depth, the gravitational acceleration and the elastic modulus of the steel.

[0015] Preferably, the pump efficiency relationship is established according to the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and further includes:

[0016] Determining the degree of filling of the oil pump according to the volume given up by the piston during the upstroke and the volume of liquid sucked into the pump during each stroke;

[0017] Wherein, the volume given up by the upstroke piston is obtained by the plunger stroke and the plunger cross-sectional area;

[0018] The volume of liquid sucked into the pump during each stroke is obtained by integrating the liquid flow rate entering the oil pump through the fixed valve during each stroke time.

[0019] Preferably, the liquid flow rate entering the oil pump through the fixed valve is determined by the flow area of ​​the fixed valve, the sinking pressure, and the pressure inside the pump.

[0020] Preferably, the pump efficiency relationship is established according to the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and further includes:

[0021] Determine the oil well pump leakage coefficient according to the liquid volume coefficient, the pump leakage, the theoretical displacement, the pump filling degree and the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency;

[0022] The leakage of the pump is obtained by the pump diameter, the radial clearance between the plunger and the pump barrel, the pressure difference of the liquid column at both ends of the plunger, the kinematic viscosity of the liquid, and the length of the plunger.

[0023] Preferably, the pump efficiency relationship is established according to the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and further includes:

[0024] The effect of volume shrinkage caused by ground crude oil degassing on pump efficiency is determined based on the liquid volume coefficient.

[0025] Preferably, the plunger motion equation is determined according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing Fourier series expansion on the function of the plunger motion speed, and includes:

[0026] The plunger acceleration time is taken as half a cycle value, and the pump efficiency relationship is expressed as a function of the plunger movement speed parameters.

[0027] Preferably, the method of obtaining the optimal parameter solution by solving the plunger motion equation using the pumping parameters in the actual operating condition of the oil well as the constraint conditions includes:

[0028] Taking pump efficiency as the optimization target, a Lagrangian function is constructed by combining the given objective function with the constraint conditions, solving the first-order partial derivative of the Lagrangian function and setting its value equal to zero to obtain the optimal parameter solution.

[0029] Preferably, the optimal parameter solution is substituted into the plunger motion equation, and the optimized pumping speed curve is expressed by the plunger motion equation, including:

[0030] Substituting the optimal parameter solution into the Fourier series expansion of the plunger motion equation, an optimized plunger motion equation is obtained.

[0031] Based on the same inventive concept, the present invention provides an oil well pumping speed curve optimization system, comprising:

[0032] The pump efficiency establishment module is used to establish a pump efficiency relationship according to the influence of the elastic expansion and contraction of the rod and pipe on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency of the pump;

[0033] A curve generating module, used to express the pump efficiency relationship as a function of the plunger movement speed, and to obtain a trapezoidal motion curve by expanding the function of the plunger movement speed;

[0034] A motion equation determination module, used to determine the plunger motion equation according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing Fourier series expansion on a function of the plunger motion speed;

[0035] An optimal solution calculation module, used to obtain an optimal parameter solution by solving the plunger motion equation using the pumping parameters in the actual operating conditions of the oil well as constraint conditions;

[0036] The optimization curve determination module is used to substitute the optimal parameter solution into the plunger motion equation, and express the optimized pumping speed curve through the plunger motion equation.

[0037] Based on the same inventive concept, the present invention provides an electronic device, comprising: a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0038] a memory storing a computer program;

[0039] The processor implements the oil well pumping speed curve optimization method when executing the program stored in the memory.

[0040] Based on the same inventive concept, the present invention provides a computer-readable storage medium storing a computer program, which implements an oil well pumping speed curve optimization method when executed by a processor.

[0041] The beneficial effects of the present invention are as follows: by establishing a relationship between pump efficiency and plunger motion speed, the plunger motion curve is expressed as a trapezoidal motion curve, the plunger motion equation is expressed in the form of a Fourier series expansion, and the constraint conditions are determined by the oil well pumping parameters to obtain the optimized plunger motion equation. The optimized oil pumping speed curve allows the plunger to move at a constant speed for a long period of time in both the up and down strokes, and can maintain a good inlet and outlet instantaneous displacement during the pumping process, thereby improving the oil pumping efficiency, while overcoming the unstable factor of the sudden acceleration change of the trapezoidal motion curve, effectively reducing the impact, and making the motor run more smoothly.

[0042] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 A flow chart of an oil well pumping speed curve optimization method in the present invention;

[0045] Figure 2 It is a schematic diagram of a trapezoidal motion curve in the present invention;

[0046] Figure 3 A comparison diagram of the plunger movement speed curves before and after optimization in the present invention;

[0047] Figure 4 A schematic diagram of an oil well pumping speed curve optimization system in the present invention;

[0048] Figure 5 Schematic diagram of an electronic device for executing the method of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0051] The present invention provides a method for optimizing the oil well pumping speed curve. Figure 1 ,include:

[0052] S101: Establish a pump efficiency relationship based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency;

[0053] S102: Expressing the pump efficiency relationship as a function of the plunger movement speed, and obtaining a trapezoidal motion curve by expanding the function of the plunger movement speed;

[0054] S103: determining a plunger motion equation according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing Fourier series expansion on a function of the plunger motion speed;

[0055] S104: using the pumping parameters in the actual operation condition of the oil well as constraint conditions to solve the plunger motion equation to obtain an optimal parameter solution;

[0056] S105: Substituting the optimal parameter solution into the plunger motion equation, and expressing an optimized pumping speed curve through the plunger motion equation.

[0057] Specifically, considering the elastic expansion and contraction of the oil rod string, the influence of gas and filling or discharging, and the influence of leakage, the relationship between pump efficiency and plunger movement speed is established, and the pump efficiency is expressed as a function of the plunger movement speed; the trapezoidal motion curve function expression is established with the maximum movement speed and acceleration time, and the plunger movement curve is expressed as a trapezoidal motion curve; the plunger motion equation is expressed in the form of Fourier series expansion, and the pump efficiency is expressed as a function of the plunger movement speed parameters; according to the actual operating conditions of the oil well, the existing stroke and stroke frequency are used as optimization constraints; the pump efficiency is taken as the optimization target, and the optimal parameters of the Fourier series expansion are calculated; the optimal solution of the maximum movement speed and acceleration time is obtained by the Langrange multiplier method, and the optimized oil well pump plunger motion equation is given.

[0058] The present invention applies the trapezoidal speed curve widely used in the field of industrial control to the oil well pumping speed optimization method, so that the plunger can move at a uniform speed for a long period of time in both the up and down strokes, and can maintain a good inlet and outlet instantaneous displacement during the pumping process, thereby improving the pumping efficiency. At the same time, it overcomes the unstable factor of the sudden acceleration change of the trapezoidal motion curve, effectively reduces the impact, and allows the motor to run more smoothly.

[0059] Specifically, according to the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, a pump efficiency relationship is established, including:

[0060] Determine the influence of the elastic expansion and contraction of the rod tube on the efficiency of the oil well pump according to the plunger stroke and the polished rod stroke of the oil well pump, wherein the plunger stroke is obtained according to the polished rod stroke and the stroke loss;

[0061] The stroke loss is determined by the cross-sectional area of ​​the plunger, the cross-sectional area of ​​the sucker rod, the cross-sectional area of ​​the sucker pipe, the total length of the sucker rod string, the liquid density, the dynamic liquid level depth, the gravitational acceleration and the elastic modulus of the steel.

[0062] The embodiment of the present invention takes into account the elastic expansion and contraction of the oil rod string, the effect of gas and the filling and leakage, and the general expression of the pump efficiency is:

[0063] η=η λ βη l η B

[0064] Among them, η λis the effect of the elastic expansion and contraction of the rod and pipe on the pump efficiency, and the effect of the elastic expansion and contraction of the rod and pipe on the pump efficiency η λ is through

[0065]

[0066] The obtained value is s p is the plunger stroke, s is the polished rod stroke, and the plunger stroke s p is through

[0067] s p =s-λ

[0068] Where λ is the stroke loss, and the stroke loss λ is obtained by

[0069]

[0070] In the above formula, s p is the plunger stroke; s is the polished rod stroke; λ is the stroke loss; f p is the cross-sectional area of ​​the plunger; f r is the cross-sectional area of ​​the sucker rod; f t is the cross-sectional area of ​​the tubing; L is the total length of the sucker rod string; ρ is the liquid density; L f is the depth of the dynamic liquid surface; g is the acceleration of gravity; E is the elastic modulus of steel, which is 2.06×10 11 pa.

[0071] In some optional embodiments, the pump efficiency relationship is established based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and further includes:

[0072] Determining the degree of filling of the oil pump according to the volume given up by the piston during the upstroke and the volume of liquid sucked into the pump during each stroke;

[0073] Wherein, the volume given up by the upstroke piston is obtained by the plunger stroke and the plunger cross-sectional area;

[0074] The volume of liquid sucked into the pump during each stroke is obtained by integrating the liquid flow rate entering the oil pump through the fixed valve during each stroke time.

[0075] Specifically, the oil well pump filling degree β is given by the formula

[0076]

[0077] The obtained value is, where V p The volume vacated by the piston during the upward stroke, V' l The volume V is the volume of liquid sucked into the pump per stroke and the volume V given up by the piston on the upstrokep is through

[0078] V p =s p *f p

[0079] The obtained volume V' of liquid sucked into the pump per stroke l is through

[0080]

[0081] It is obtained by integrating the liquid flow rate entering the oil pump through the fixed valve during each stroke time.

[0082] To calculate the volume of liquid sucked into the pump per stroke, it is necessary to know the liquid flow rate q entering the oil pump through the fixed valve. o The liquid flow rate entering the oil pump through the fixed valve is determined by the fixed valve flow area, the sinking pressure, and the pressure inside the pump.

[0083]

[0084] The above formula V p The volume vacated by the piston during the upward stroke; V' l is the volume of liquid sucked into the pump per stroke; q o is the liquid flow rate entering the oil pump through the fixed valve; C is a constant related to the unit system and is dimensionless; A s is the fixed valve flow area; p s is the sinking pressure; p(t) is the pressure inside the pump; ξ v is the fixed valve resistance coefficient.

[0085] In some optional embodiments, the pump efficiency relationship is established based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and further includes:

[0086] Determine the oil well pump leakage coefficient according to the liquid volume coefficient, the pump leakage, the theoretical displacement, the pump filling degree and the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency;

[0087] The leakage of the pump is obtained by the pump diameter, the radial clearance between the plunger and the pump barrel, the pressure difference of the liquid column at both ends of the plunger, the kinematic viscosity of the liquid, and the length of the plunger.

[0088] Specifically, the leakage coefficient η l is through

[0089]

[0090] The pump leakage is obtained by

[0091]

[0092] In the above formula, B1 is the liquid volume coefficient; q is the pump leakage; Q t is the theoretical displacement; D is the pump diameter; e is the radial clearance between the plunger and the pump barrel; ΔH is the pressure difference of the liquid column at both ends of the plunger; ν is the kinematic viscosity of the liquid, and l is the length of the plunger.

[0093] In some optional embodiments, the pump efficiency relationship is established based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and further includes:

[0094] The effect of volume shrinkage caused by ground crude oil degassing on pump efficiency is determined based on the liquid volume coefficient.

[0095] Specifically, the effect of volume shrinkage caused by surface crude oil degassing on pump efficiency η B is through

[0096]

[0097] Obtained, where B1 is the liquid volume coefficient.

[0098] In the above step S102: the pump efficiency relationship is expressed as a function of the plunger movement speed, and a trapezoidal motion curve is obtained by expanding the function of the plunger movement speed;

[0099] Specifically, see Figure 2 , the trapezoidal motion curve is an odd function with a period of T, and the maximum speed of the plunger is A max , the plunger acceleration time is d, in the interval The function expression is:

[0100]

[0101] In the formula, A max is the maximum speed of the plunger; t is the acceleration time of the plunger; T is the movement period of the plunger. During the speed change process, the acceleration remains unchanged, and the motor runs relatively smoothly. When the oil pump plunger moves in a trapezoidal curve, there is a long period of uniform movement in both the up and down strokes, and a good inlet and outlet instantaneous displacement can be maintained during the pumping process.

[0102] In some optional embodiments, the plunger motion equation is determined according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing Fourier series expansion on a function of the plunger motion speed, and includes:

[0103] The plunger acceleration time takes a half-cycle value, and the pump efficiency relationship is expressed as a function of the plunger motion speed parameter η=f(v).

[0104] Specifically, since the trapezoidal motion curve will overshoot at the turning point of constant acceleration, it is easy to cause shock and vibration to the system. Therefore, the piston motion equation is expanded into a Fourier series form and converted into a continuously differentiable function to overcome the unstable factor of the sudden acceleration change of the trapezoidal motion curve, effectively reduce the impact, and make the motor run more smoothly.

[0105] The trapezoidal equation of motion is The Fourier series expansion of is:

[0106]

[0107] n=1,2,3……n

[0108] Where ω is the angular velocity, rad / s.

[0109] Since the degree of filling in the pump efficiency expression is the ratio of the volume of liquid entering the pump during the upstroke to the volume of liquid released by the plunger, in the calculation of pump efficiency, t is taken as The pump efficiency is expressed as a function of the plunger speed parameter, that is, η = f(A max , d).

[0110] In some optional embodiments, the method of obtaining an optimal parameter solution by solving the plunger motion equation using the pumping parameters in the actual operating conditions of the oil well as constraints includes:

[0111] According to the actual operating conditions of the oil well, the existing pumping parameters are used as constraints, that is, the stroke and stroke frequency remain unchanged:

[0112]

[0113] Taking the pump efficiency η as the optimization target, the Lagrangian function is constructed by combining the objective function with the constraints, and the first-order partial derivative is solved and its value is set equal to zero to obtain the optimal parameter solution.

[0114] Specifically, let the objective function η = f(A max , d), the constraints are Construct the Lagrangian function:

[0115]

[0116] Let F(A max , d, γ) for A max , d, the first-order partial derivative of γ is equal to zero, that is,

[0117]

[0118]

[0119]

[0120] Solve the above equations to get A max , d.

[0121] Substituting the optimal parameter solution into the plunger motion equation, the optimized pumping speed curve is expressed by the plunger motion equation, including:

[0122] Substituting the optimal parameter solution into the Fourier series expansion of the plunger motion equation, an optimized plunger motion equation is obtained.

[0123] A obtained by the Langrange multiplier method max , d, is the objective function pump efficiency η = f(A max , d) Under the constraints The optimal solution under .

[0124] A max , d is substituted into the plunger trapezoidal motion velocity equation The optimized motion equation of the oil well pump plunger is obtained by using the Fourier series expansion of

[0125] Substitute the optimal parameter solution into the plunger motion equation, and express the optimized pumping speed curve through the plunger motion equation. Figure 3 .

[0126] With respect to the embodiments of the present invention, the present invention is exemplarily described below in combination with data.

[0127] Taking a certain well as an example, a method for optimizing an oil well pumping speed curve in an embodiment of the present invention is further described.

[0128] The diameter of the oil pipe of a well is 56mm, the diameter of the plunger is 28mm, the diameter of the sucker rod is 22mm, the length of the plunger is 1.5m, the radial clearance between the plunger and the pump barrel is 0.02mm, the stroke of the rod is 2.5m, and the stroke time is 3.2min -1 , dynamic liquid level depth 1136m, well fluid density 860kg / m 3 , kinematic viscosity 20mm 2 , crude oil volume coefficient 1.2, pump efficiency 37.9%.

[0129] Establish the relationship between pump efficiency and plunger movement speed.

[0130] Considering the elastic expansion and contraction of the oil rod string, the effect of gas and filling or not filling, and the effect of leakage, the general expression of pump efficiency can be written as:

[0131] η=η λβη l η B

[0132] Among them, η λ The influence of rod and tube elastic expansion and contraction on pump efficiency:

[0133]

[0134] s p is the plunger stroke:

[0135] s p =s-λ=2.5-0.9556=2.4m

[0136] λ is the stroke loss:

[0137]

[0138] Where β is the degree of filling of the pump:

[0139]

[0140] V p Volume vacated by the piston for the upstroke:

[0141] V p =s p +f p =2.4×6.15×10 -4 =1.48×10 -3 m 3

[0142] V' l The volume of liquid sucked into the pump per stroke:

[0143]

[0144] q o The liquid flow rate entering the oil well pump through the fixed valve is:

[0145]

[0146] Where V p The volume vacated by the piston during the upward stroke, m 3 ; V' l is the volume of liquid sucked into the pump per stroke, m 3 ;q o is the liquid flow rate entering the oil well pump through the fixed valve, m 3 / s; C is a constant related to the unit system and is dimensionless; A s is the fixed valve flow area, m 2 ;p sis the sinking pressure, MPa; p(t) is the pressure inside the pump, MPa; p(t) is the pressure inside the pump, MPa; ξ v is the fixed valve resistance coefficient, dimensionless.

[0147] Among them, η l is the leakage coefficient:

[0148]

[0149] q is the leakage of the pump:

[0150]

[0151] Where B1 is the liquid volume coefficient, dimensionless; q is the pump leakage, m 3 / s;Q t is the theoretical displacement, m 3 / s; D is the pump diameter, m; e is the radial clearance between the plunger and the pump barrel, m; ΔH is the pressure difference of the liquid column at both ends of the plunger, m; ν is the kinematic viscosity of the liquid, m 2 / s, l is the plunger length, m.

[0152] Among them, η B The impact of volume shrinkage caused by ground crude oil degassing on pump efficiency:

[0153]

[0154] Where B1 is the liquid volume coefficient, dimensionless.

[0155] According to the above formulas, the pump efficiency is expressed as a function of the plunger speed, that is,

[0156]

[0157] The plunger motion curve is represented as a trapezoidal motion curve.

[0158] The trapezoidal speed curve is an acceleration and deceleration control strategy widely used in the field of industrial control. The acceleration remains unchanged during the speed change process, and the motor runs more smoothly. When the oil pump plunger moves in a trapezoidal curve, there is a long period of uniform motion in both the up and down strokes, and a good inlet and outlet instantaneous displacement can be maintained during the pumping process.

[0159] The plunger motion speed curve is represented as a trapezoidal curve, such as Figure 2 As shown, the trapezoidal curve is an odd function with a period of T, and the maximum movement speed of the plunger is A max , the plunger acceleration time is d, in the interval The function expression is:

[0160]

[0161] In the formula, A max is the maximum movement speed of the plunger, m / s; d is the plunger acceleration time, t; T is the plunger movement period, s.

[0162] The equations of motion of the plunger are expressed in the form of Fourier series expansion.

[0163] Since the trapezoidal speed curve will overshoot at the turning point of constant acceleration, it is easy to cause shock and vibration to the system. Therefore, the piston motion equation is expanded into a Fourier series form and converted into a continuous and differentiable function to overcome the unstable factor of the sudden acceleration change of the trapezoidal motion curve, effectively reduce the shock, and make the motor run more smoothly.

[0164] The velocity equation of the plunger trapezoidal motion is The Fourier series expansion of is:

[0165]

[0166] n=1,2,3……n

[0167] Where ω is the angular velocity, rad / s.

[0168] Since the degree of filling in the pump efficiency expression is the ratio of the volume of liquid entering the pump during the upstroke to the volume of liquid released by the plunger, t is taken as 9.375s in the calculation of pump efficiency. The pump efficiency is expressed as a function of the plunger motion speed parameter, that is,

[0169]

[0170] The constraints are determined by the oil well pumping parameters.

[0171] According to the actual operating conditions of the oil well, the existing pumping parameters are used as constraints, that is, the stroke and stroke frequency remain unchanged:

[0172]

[0173] Compute the optimal parameters of the Fourier series expansion.

[0174] Taking the pump efficiency η as the optimization target, the given objective function η=f(A max , d), the constraints are Construct the Lagrangian function:

[0175]

[0176] Let F(A max , d, γ) for A max , d, the first-order partial derivative of γ is equal to zero. When n is 5, the above equations can be solved to obtain A max =0.37m / s, d=2.81s.

[0177] The optimized motion equation of the oil well pump plunger is given.

[0178] A max , d is substituted into the plunger trapezoidal motion velocity equation The Fourier series expansion of the optimized pump plunger motion equation is obtained, and the plunger speed-time curve is plotted, as shown in the attached figure. Figure 3 shown.

[0179] Comparing the plunger motion curves before and after optimization, compared with the plunger motion curve before optimization, the optimized plunger motion curve keeps the acceleration unchanged during the speed change process of the up and down strokes, and has a longer period of uniform motion, which is conducive to the smooth suction and discharge of the fluid in the pump and reduces the liquid impact.

[0180] Through test comparison, under the premise that the existing pumping parameters remain unchanged, the optimized pump efficiency increased from 37.9% to 42.5%, an increase of 4.6%, with obvious improvement effect.

[0181] Based on the same inventive concept, the present invention also provides an oil well pumping speed curve optimization system, see Figure 4 ,include:

[0182] A pump efficiency establishment module 41 is used to establish a pump efficiency relationship according to the influence of the elastic expansion and contraction of the rod and pipe on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency of the pump;

[0183] A curve generating module 42, for expressing the pump efficiency relationship as a function of the plunger movement speed, and obtaining a trapezoidal movement curve by expanding the function of the plunger movement speed;

[0184] A motion equation determination module 43, configured to determine a plunger motion equation according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing a Fourier series expansion on a function of the plunger motion velocity;

[0185] The optimal solution calculation module 44 is used to obtain the optimal parameter solution by solving the plunger motion equation using the pumping parameters in the actual operation condition of the oil well as the constraint conditions;

[0186] The optimization curve determination module 45 is used to substitute the optimal parameter solution into the plunger motion equation, and express the optimized pumping speed curve through the plunger motion equation.

[0187] Based on the same inventive concept, the present invention also provides an electronic device 161, see Figure 5, including a processor 164, a communication interface 165, a memory 162 and a communication bus, wherein the processor 164, the communication interface 165 and the memory 162 communicate with each other through the communication bus;

[0188] A memory 162 storing a computer program 163;

[0189] The processor 164 implements the oil well pumping speed curve optimization method when executing the program stored in the memory 162.

[0190] The above communication bus may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus may be divided into an address bus, a data bus, a control bus, etc.

[0191] The communication interface 165 is used for communication between the electronic device 161 and other devices.

[0192] The memory 162 may include a random access memory 162 (RAM), or may include a non-volatile memory 162 (non-volatile memory), such as at least one disk memory 162. Optionally, the memory 162 may also be at least one storage device located away from the processor 164.

[0193] The above-mentioned processor 164 can be a general-purpose processor 164, including a central processing unit 164 (CPU), a network processor 164 (NP), etc.; it can also be a digital signal processor 164 (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components.

[0194] Based on the same inventive concept, the present invention further provides a computer-readable storage medium storing a computer program 163 , and when the computer program 163 is executed by a processor 164 , the oil well pumping speed curve optimization method is implemented.

[0195] The computer-readable storage medium may be included in the device / apparatus described in the above embodiment; or it may exist independently without being assembled into the device / apparatus. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the oil well pumping speed curve optimization method according to the embodiment of the present disclosure is implemented.

[0196] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for optimizing an oil well pumping speed curve, characterized in that: include: According to the influence of elastic expansion and contraction of rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the volume contraction caused by surface crude oil degassing on the pump efficiency, a pump efficiency relationship is established; The pump efficiency relationship is expressed as a function of the plunger movement speed, and a trapezoidal motion curve is obtained by expanding the function of the plunger movement speed; Determining a plunger motion equation according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing a Fourier series expansion on a function of the plunger motion speed; Taking the pumping parameters in the actual operation condition of the oil well as the constraint conditions, the optimal parameter solution is obtained by solving the plunger motion equation; The optimal parameter solution is substituted into the plunger motion equation, and the optimized pumping speed curve is expressed by the plunger motion equation.

2. The method according to claim 1, characterized in that According to the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, a pump efficiency relationship is established, including: Determine the influence of the elastic expansion and contraction of the rod tube on the efficiency of the oil well pump according to the plunger stroke and the polished rod stroke of the oil well pump, wherein the plunger stroke is obtained according to the polished rod stroke and the stroke loss; The stroke loss is determined by the cross-sectional area of ​​the plunger, the cross-sectional area of ​​the sucker rod, the cross-sectional area of ​​the sucker pipe, the total length of the sucker rod string, the liquid density, the dynamic liquid level depth, the gravitational acceleration and the elastic modulus of the steel.

3. The method according to claim 1 or 2, characterized in that: The pump efficiency relationship is established based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and also includes: Determining the degree of filling of the oil pump according to the volume given up by the piston during the upstroke and the volume of liquid sucked into the pump during each stroke; Wherein, the volume given up by the upstroke piston is obtained by the plunger stroke and the plunger cross-sectional area; The volume of liquid sucked into the pump during each stroke is obtained by integrating the liquid flow rate entering the oil pump through the fixed valve during each stroke time.

4. The method according to claim 1, characterized in that: The liquid flow rate entering the oil pump through the fixed valve is determined by the fixed valve flow area, the sinking pressure and the pressure inside the pump.

5. The method according to claim 4, characterized in that The pump efficiency relationship is established based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and also includes: Determine the oil well pump leakage coefficient according to the liquid volume coefficient, the pump leakage, the theoretical displacement, the pump filling degree and the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency; The leakage of the pump is obtained by the pump diameter, the radial clearance between the plunger and the pump barrel, the pressure difference of the liquid column at both ends of the plunger, the kinematic viscosity of the liquid, and the length of the plunger.

6. The method according to claim 5, characterized in that The pump efficiency relationship is established based on the influence of the elastic expansion and contraction of the rod and tube on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency, and also includes: The effect of volume shrinkage caused by ground crude oil degassing on pump efficiency is determined based on the liquid volume coefficient.

7. The method according to claim 1, characterized in that The plunger motion equation is determined according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing Fourier series expansion on the function of the plunger motion speed, and includes: The plunger acceleration time is taken as half a cycle value, and the pump efficiency relationship is expressed as a function of the plunger movement speed parameters.

8. The method according to claim 1, characterized in that The method of obtaining the optimal parameter solution by solving the plunger motion equation using the pumping parameters in the actual operating conditions of the oil well as the constraint conditions includes: Taking pump efficiency as the optimization target, a Lagrangian function is constructed by combining the given objective function with the constraint conditions, solving the first-order partial derivative of the Lagrangian function and setting its value equal to zero to obtain the optimal parameter solution.

9. The method according to claim 1, characterized in that: Substituting the optimal parameter solution into the plunger motion equation, the optimized pumping speed curve is expressed by the plunger motion equation, including: Substituting the optimal parameter solution into the Fourier series expansion of the plunger motion equation, an optimized plunger motion equation is obtained.

10. An oil well pumping speed curve optimization system, characterized in that: include: The pump efficiency establishment module is used to establish a pump efficiency relationship according to the influence of the elastic expansion and contraction of the rod and pipe on the pump efficiency, the filling degree of the pump, the leakage coefficient of the pump and the influence of the volume contraction caused by the degassing of the ground crude oil on the pump efficiency of the pump; A curve generating module, used to express the pump efficiency relationship as a function of the plunger movement speed, and to obtain a trapezoidal motion curve by expanding the function of the plunger movement speed; A motion equation determination module, used to determine the plunger motion equation according to the trapezoidal motion curve, wherein the plunger motion equation is obtained by performing Fourier series expansion on a function of the plunger motion speed; An optimal solution calculation module, used to obtain an optimal parameter solution by solving the plunger motion equation using the pumping parameters in the actual operating conditions of the oil well as constraint conditions; The optimization curve determination module is used to substitute the optimal parameter solution into the plunger motion equation, and express the optimized pumping speed curve through the plunger motion equation.

11. An electronic device, characterized in that: include: A processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; a memory storing a computer program; The processor, when executing the program stored in the memory, implements the oil well pumping speed curve optimization method as described in any one of claims 1 to 9.

12. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the method for optimizing the oil well pumping speed curve according to any one of claims 1 to 9 is implemented.

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