Method, system, processor and storage medium for controlling bottom hole pressure

Abstract

The present application discloses a method, system, processor, and storage medium for controlling bottomhole pressure, belonging to the technical field of oil and gas exploration and development. The method comprises: obtaining the actual wellhead pressure and the target wellhead pressure; adjusting the parameters of a pre-built PID controller using a dung beetle optimization algorithm according to the actual wellhead pressure and the target wellhead pressure to obtain the control quantity output by the PID controller; determining the opening control signal of the throttle valve in the well control equipment according to the control quantity based on the transfer function of the predetermined well control equipment; and adjusting the opening of the throttle valve using the opening control signal to achieve control of the bottomhole pressure. The present application can adjust the parameters of the PID controller in real time under different construction conditions, reducing the influence of the nonlinear characteristics of the throttle valve on the PID control, thereby improving the control accuracy of the bottomhole pressure.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas exploration and development, and in particular to a method, system, processor, and storage medium for controlling bottom hole pressure. Background Art

[0002] In order to prevent accidents such as overflows and blowouts, managed pressure drilling technology has been proposed. Managed pressure drilling is an advanced drilling technology and has been proven to be effective in wells with narrow safety pressure windows. Current research on managed pressure drilling is divided into more complete pressure control methods, automatic pressure control equipment, and more accurate wellbore hydraulic models. Among them, research on pressure control methods has mostly stopped at simulation, and due to the complex principles and limited industrial applications of pressure control methods, they have not been applied to actual managed pressure drilling processes. There are also some problems with the automated equipment related to managed pressure drilling. For example, the constant bottomhole pressure method and equipment based on Pressure While Drilling (PWD) are only applicable to managed pressure drilling under constant bottomhole pressure conditions. For another example, the control accuracy of the PCDS-I managed pressure drilling system is about 0.2 MPa, and its pressure control accuracy is relatively low. Therefore, the existing pressure control method in the managed pressure drilling process has the problem of low control accuracy. Summary of the Invention

[0003] The purpose of the embodiments of the present application is to provide a method, system, processor and storage medium for controlling bottom hole pressure, so as to solve the problem of low control accuracy of the pressure control method in the prior art.

[0004] To achieve the above objectives, a first aspect of an embodiment of the present application provides a method for controlling bottom hole pressure, comprising:

[0005] Obtain actual wellhead pressure and target wellhead pressure;

[0006] According to the actual wellhead pressure and the target wellhead pressure, the parameters of the pre-built PID controller are tuned by the dung beetle optimization algorithm to obtain the control quantity output by the PID controller;

[0007] Based on a predetermined transfer function of the well control equipment, determining an opening control signal of a throttle valve in the well control equipment according to a control quantity;

[0008] The opening of the throttle valve is adjusted by the opening control signal to achieve control of the bottom hole pressure.

[0009] In an embodiment of the present application, the parameters of the PID controller include proportional parameters, integral parameters and differential parameters. According to the actual wellhead pressure and the target wellhead pressure, the parameters of the pre-built PID controller are adjusted by the dung beetle optimization algorithm, including: initializing the current position of each dung beetle in the dung beetle group; obtaining the fitness function of the dung beetle optimization algorithm; determining the fitness value of each dung beetle at the current position according to the fitness function, the actual wellhead pressure and the target wellhead pressure; updating the target dung beetle according to the fitness value of each dung beetle at the current position; updating the current position of each dung beetle, and returning to execute the step of determining the fitness value of each dung beetle at the current position according to the fitness function, until the number of executions reaches a preset number of iterations, so as to determine the proportional parameter, integral parameter and differential parameter of the PID controller according to the current position of the target dung beetle.

[0010] In an embodiment of the present application, updating the target dung beetle according to the fitness value of each dung beetle at the current position includes: comparing the fitness value of each dung beetle at the current position, and updating the dung beetle with the largest fitness value as the target dung beetle.

[0011] In an embodiment of the present application, updating the current position of each dung beetle includes: determining the type corresponding to each dung beetle; determining the position update method of each dung beetle according to the type; and updating the current position of each dung beetle according to the position update method.

[0012] In an embodiment of the present application, the well control equipment also includes a signal amplifier and an electro-hydraulic proportional valve. The determination of the transfer function of the well control equipment includes: respectively obtaining the component control functions of the signal amplifier, the electro-hydraulic proportional valve and the throttle valve; and determining the transfer function of the well control equipment based on the component control functions of the signal amplifier, the electro-hydraulic proportional valve and the throttle valve.

[0013] In the embodiment of the present application, the transfer function of the well control equipment satisfies formula (1):

[0014]

[0015]

[0016] Among them, G(s) is the opening control signal, δ Q is the forward movement coefficient of the electro-hydraulic proportional valve, δ p is the negative movement coefficient of the electro-hydraulic proportional valve, A is the effective area of ​​the hydraulic oil acting on the piston, s is the sampling period, C ec is the external leakage coefficient of the hydraulic cylinder, C ic is the leakage coefficient in the hydraulic cylinder, β e is the effective bulk elastic modulus of the hydraulic oil, L v is the displacement of the throttle valve core, V is the volume of the hydraulic cylinder, F d is the force exerted by the drilling fluid on the throttle valve core, and m is the total mass of the hydraulic cylinder actuator.

[0017] A second aspect of an embodiment of the present application provides a processor configured to execute the above-mentioned method for controlling bottom hole pressure.

[0018] A third aspect of an embodiment of the present application provides a system for controlling bottom hole pressure, comprising: a processor; a PID controller; and well control equipment, including a throttle valve.

[0019] In an embodiment of the present application, the well control equipment further includes: a signal amplifier; and an electro-hydraulic proportional valve.

[0020] A fourth aspect of an embodiment of the present application provides a machine-readable storage medium having stored thereon instructions for enabling a machine to execute the above-mentioned method for controlling bottom hole pressure.

[0021] The above technical solution first adjusts the parameters of the pre-built PID controller based on the actual wellhead pressure and target wellhead pressure obtained using the dung beetle optimization algorithm to obtain the control quantity output by the PID controller. Then, based on the transfer function of the predetermined well control equipment, the opening control signal of the throttle valve in the well control equipment is determined according to the control quantity. The opening of the throttle valve is then adjusted by the opening control signal to achieve control of the bottomhole pressure. This application uses the dung beetle optimization algorithm to adjust the parameters of the pre-built PID controller based on the actual wellhead pressure and target wellhead pressure obtained. It can adjust the parameters of the PID controller in real time under different construction conditions, reduce the impact of the nonlinear characteristics of the throttle valve on the PID control, and thus improve the control accuracy of the bottomhole pressure.

[0022] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present application but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0024] Figure 1 A flow chart schematically illustrates a method for controlling bottom hole pressure according to an embodiment of the present application;

[0025] Figure 2 The schematic diagram shows a principle diagram of a system for controlling bottom hole pressure according to an embodiment of the present application.

[0026] Description of Reference Numerals

[0027] 210 PID Controller 220 Well Control Equipment

[0028] 221 Signal amplifier 222 Electro-hydraulic proportional valve

[0029] 223 Hydraulic line 224 Throttle valve

[0030] 230 pressure sensor DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0033] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0034] Figure 1 A flow chart of a method for controlling bottom hole pressure according to an embodiment of the present application is schematically shown. Figure 1 As shown, an embodiment of the present application provides a method for controlling bottom hole pressure. Taking the method applied to a processor as an example, the method may include the following steps:

[0035] Step S101: Acquire actual wellhead pressure and target wellhead pressure.

[0036] Step S102: According to the actual wellhead pressure and the target wellhead pressure, the parameters of the pre-built PID controller are adjusted by the dung beetle optimization algorithm to obtain the control quantity output by the PID controller.

[0037] Step S103: Based on the predetermined transfer function of the well control equipment, an opening control signal of the throttle valve in the well control equipment is determined according to the control amount.

[0038] Step S104: adjusting the opening of the throttle valve by the opening control signal to control the bottom hole pressure.

[0039] There is a certain correlation between the wellhead pressure (i.e., wellhead back pressure) and the bottom hole pressure. Therefore, in an embodiment of the present application, the processor can determine the opening control signal of the throttle valve based on the actual wellhead pressure and the target wellhead pressure, so as to adjust the opening of the throttle valve according to the opening control signal to achieve control of the bottom hole pressure. Specifically, through the pressure sensor installed at the oil drilling site, the processor can obtain the actual wellhead pressure. Combined with the pre-set target wellhead pressure, the processor can determine the error between the actual wellhead pressure and the target wellhead pressure, and then adjust the parameters of the pre-built PID controller through the dung beetle optimization algorithm based on the error between the actual wellhead pressure and the target wellhead pressure. The parameters of the PID controller include proportional parameters, integral parameters, and differential parameters. In this way, after clarifying the proportional parameters, integral parameters, and differential parameters of the PID controller, the processor can output the corresponding control quantity according to the actual wellhead pressure and the target wellhead pressure through the PID controller.

[0040] Well control equipment includes but is not limited to a signal amplifier, an electro-hydraulic proportional valve, hydraulic pipelines, and a throttle valve. After the PID controller outputs the control variable, it must sequentially pass through the signal amplifier and the electro-hydraulic proportional valve to control the throttle valve. This involves a transfer process within the well control equipment. Therefore, the final output throttle valve opening control signal must be determined by combining the well control equipment's transfer function with the control variable. This allows the electro-hydraulic proportional valve to pump hydraulic oil into the hydraulic pipeline based on the opening control signal amplified by the signal amplifier, changing the displacement of the throttle valve piston and thus adjusting the throttle valve opening. Due to the inherent properties of hydraulic oil, such as compressibility, temperature sensitivity, and flow characteristics, its characteristic parameters change during system operation, necessitating system simplification. Specifically, the system can be assumed to utilize an ideal constant-pressure oil source with a constant supply pressure and zero return pressure. The hydraulic oil's temperature and density remain constant, and the displacement of the electro-hydraulic proportional valve is symmetrical with the flow dead zone. Furthermore, losses in the hydraulic manifold, friction in the hydraulic oil, and the load viscous damping coefficient are not considered. This simplifies the system and ultimately yields the transfer function of the well control equipment. In this way, the processor can adjust the opening of the throttle valve through the opening control signal to change the bottom hole pressure and realize the control of the bottom hole pressure.

[0041] The above technical solution first adjusts the parameters of the pre-built PID controller based on the actual wellhead pressure and target wellhead pressure obtained using the dung beetle optimization algorithm to obtain the control quantity output by the PID controller. Then, based on the transfer function of the predetermined well control equipment, the opening control signal of the throttle valve in the well control equipment is determined according to the control quantity. The opening of the throttle valve is then adjusted by the opening control signal to achieve control of the bottomhole pressure. This application uses the dung beetle optimization algorithm to adjust the parameters of the pre-built PID controller based on the actual wellhead pressure and target wellhead pressure obtained. It can adjust the parameters of the PID controller in real time under different construction conditions, reduce the impact of the nonlinear characteristics of the throttle valve on the PID control, and thus improve the control accuracy of the bottomhole pressure.

[0042] In an embodiment of the present application, the parameters of the PID controller include proportional parameters, integral parameters and differential parameters. According to the actual wellhead pressure and the target wellhead pressure, the parameters of the pre-built PID controller are adjusted by the dung beetle optimization algorithm, which may include: initializing the current position of each dung beetle in the dung beetle group; obtaining the fitness function of the dung beetle optimization algorithm; determining the fitness value of each dung beetle at the current position according to the fitness function, the actual wellhead pressure and the target wellhead pressure; updating the target dung beetle according to the fitness value of each dung beetle at the current position; updating the current position of each dung beetle, and returning to execute the step of determining the fitness value of each dung beetle at the current position according to the fitness function, until the number of executions reaches a preset number of iterations, so as to determine the proportional parameter, integral parameter and differential parameter of the PID controller according to the current position of the target dung beetle.

[0043] Specifically, the proportional, integral, and differential parameters of the PID controller are used as a solution in three-dimensional space, with the proportional, integral, and differential parameters corresponding to the dung beetle's position (x, y, z) in three-dimensional space. After setting initial conditions such as the position range of each dung beetle, the population size of the dung beetle swarm, the preset number of iterations, and the stabilization time, the processor can initialize the current position of each dung beetle in the swarm and obtain a fitness function. In one example, the PID controller parameter range can be set to [0.0001, 20], the population size of the dung beetle swarm to 50, the preset number of iterations to 200, and the stabilization time to 20. The fitness function is associated with the control performance of the PID controller. Based on automatic control theory, any of the following can be selected as a reference for constructing the fitness function: the integral of the squared error, the integral of the absolute error, the integral of the time squared error, or the integral of the time multiplied by the absolute error. Taking the integral of the time multiplied by the absolute error as an example, the processor can use the inverse of the integral of the time multiplied by the absolute error as the fitness function. Furthermore, the processor can determine the error between the actual wellhead pressure and the target wellhead pressure and, based on the fitness function and the error, determine the fitness value of each dung beetle at its current location. Since a larger fitness value indicates better control performance, the processor can determine the dung beetle with the highest fitness value at its current location and designate it as the target dung beetle. Dung beetles can be divided into four types: rolling dung beetles, breeding dung beetles, small dung beetles, and stealing dung beetles. Each type of dung beetle corresponds to a different position update method. Therefore, the processor can determine the position update method for each dung beetle based on its corresponding type, and then update the current position of each dung beetle. After updating the current position of each dung beetle, the fitness value of each dung beetle at its current location is again determined based on the fitness function. The target dung beetle is then updated based on the fitness value of each dung beetle at its current location, and this process is repeated until a preset number of iterations is reached. The preset number of iterations can be adjusted based on actual conditions. When the number of executions reaches a preset number of iterations, the loop ends, and the processor can determine the proportional, integral, and differential parameters of the PID controller based on the current position of the target dung beetle. This completes the process of tuning the PID controller parameters using the dung beetle optimization algorithm.

[0044] In an embodiment of the present application, updating the target dung beetle according to the fitness value of each dung beetle at the current position may include: comparing the fitness value of each dung beetle at the current position, and updating the dung beetle with the largest fitness value as the target dung beetle.

[0045] Specifically, since a larger fitness value results in better control performance, to further enhance the control performance of the PID controller, in any loop, after determining the fitness value of each dung beetle at its current position, the processor can compare the fitness values ​​of the dung beetles at their current positions and update the dung beetle with the highest fitness value as the target dung beetle. In this way, the processor can determine the parameters of the PID controller based on the final determined current position of the target dung beetle when the number of iterations reaches a preset number.

[0046] In an embodiment of the present application, updating the current position of each dung beetle may include: determining the type corresponding to each dung beetle; determining a position update method for each dung beetle according to the type; and updating the current position of each dung beetle according to the position update method.

[0047] Specifically, dung beetles can be divided into four types: rolling dung beetles, breeding dung beetles, small dung beetles, and stealing dung beetles. The proportion of each type of dung beetle in the dung beetle population can be determined based on actual conditions. Since each type of dung beetle corresponds to a different position update method, the processor can determine the position update method of each dung beetle based on the type of dung beetle, and then update the current position of each dung beetle. Specifically, when the type of dung beetle is a rolling dung beetle, the current position of the rolling dung beetle can be updated using formula (2):

[0048]

[0049] When the ball-rolling dung beetle moves to the boundary or coincides with the position of other dung beetles, the tangent function can be used to simulate the dancing behavior of the ball-rolling dung beetle to obtain a new rolling direction, that is, to update the current position of the ball-rolling dung beetle through formula (3):

[0050] x i (t+1)=x i (t)+tan(θ)|x i (t)-x i (t-1)|; (3)

[0051] Among them, t is the current execution number, x i (t) is the position of the i-th ball beetle at the t-th iteration, α is the natural coefficient, usually assigned a value of -1 or 1, k is the constant of the deflection coefficient, and its value range is (0,0.2], b is a constant belonging to (0,1), X w is the global worst position, Δx is used to simulate the change of light intensity, and the value range of θ is (0,π]. When θ is equal to 0, π / 2 or π, the rolling direction of the rolling ball dung beetle is not updated.

[0052] When the type of dung beetle is a breeding dung beetle, its egg-laying area satisfies formula (4):

[0053]

[0054] Since the location range of the breeding dung beetle changes dynamically with the number of executions of the algorithm, the current location of the breeding dung beetle is also dynamic during the iteration process and can be determined according to formula (5):

[0055] B i (t+1)=X * +b1×(B i (t)-Lb * )+b2×(B i (t)-Ub * ); (5)

[0056] Among them, X * is the current local optimal position, Lb * is the lower bound of the spawning area, Ub * is the upper limit of the egg-laying area, R can determine the location range of the breeding dung beetles, T max is the preset number of iterations, t is the current number of executions, Lb is the lower bound of the PID controller parameters, Ub is the upper bound of the PID controller parameters, B i (t+1) is the position of the i-th breeding dung beetle at the t+1th iteration, B i (t) is the position of the i-th breeding dung beetle at the t-th iteration, b1 and b2 represent two independent random vectors of size 1×D, and D is the dimension of the parameters of the PID controller.

[0057] When the type of dung beetle is the small dung beetle, its optimal foraging area satisfies formula (6):

[0058]

[0059] Therefore, the current position of the dung beetle can be updated by formula (7):

[0060] x j (t+1)=x j (t)+C1×(x j (t)-Lb b )+C2×(x j (t)-Ub b ); (7)

[0061] Among them, X b is the global optimal position, Lb b is the upper bound of the optimal foraging area, Ub b is the lower bound of the optimal foraging area, R can determine the location range of the dung beetle, Lb is the lower bound of the PID controller parameters, Ub is the upper bound of the PID controller parameters, x i (t+1) is the position of the jth dung beetle at the t+1th iteration, x j(t) is the position of the j-th dung beetle at the t-th iteration, C1 is a random number that obeys the normal distribution, and C2 is a random vector belonging to (0,1).

[0062] When the type of dung beetle is the thieving dung beetle, we know that X b For the global optimal position, we can assume that X b The vicinity is the best location for the thieving dung beetle to compete for food, so the current location of the thieving dung beetle can be updated by formula (8):

[0063] x k (t+1)=X b +S×g×(|x k (t)-X * |+|x k (t)-X b |); (8)

[0064] Among them, x k (t+1) is the position of the kth thieving dung beetle at the t+1th iteration, x k (t) is the position of the kth thieving dung beetle at the tth iteration, X b is the global optimal position, X * is the current local optimal position, S is a constant, g is a random vector of size 1×D that obeys the normal distribution, and D is the dimension of the PID controller parameters.

[0065] In this way, the processor can update the current position of the dung beetle for different types of dung beetles during each iteration, so as to determine the parameters of the PID controller when the number of executions reaches a preset number of iterations.

[0066] In an embodiment of the present application, the well control equipment also includes a signal amplifier and an electro-hydraulic proportional valve. The determination of the transfer function of the well control equipment may include: respectively obtaining the component control functions of the signal amplifier, the electro-hydraulic proportional valve and the throttle valve; and determining the transfer function of the well control equipment based on the component control functions of the signal amplifier, the electro-hydraulic proportional valve and the throttle valve.

[0067] Specifically, the well control equipment includes but is not limited to a signal amplifier, an electro-hydraulic proportional valve, and a throttle valve. After the PID controller outputs the control quantity, the control quantity needs to pass through the signal amplifier and the electro-hydraulic proportional valve in sequence to realize the control of the throttle valve. There is a transfer process in the well control equipment. Therefore, it is necessary to combine the transfer function of the well control equipment and the control quantity to determine the final output throttle valve opening control signal, so that the electro-hydraulic proportional valve pumps hydraulic oil into the hydraulic pipeline according to the opening control signal amplified by the signal amplifier, changes the displacement of the throttle valve piston, and thus adjusts the throttle valve opening. Therefore, according to the working characteristics of the signal amplifier, the electro-hydraulic proportional valve, and the displacement sensor of the throttle valve, the processor can respectively obtain the component control functions of the signal amplifier, the electro-hydraulic proportional valve, and the throttle valve. The component control functions of the signal amplifier, the electro-hydraulic proportional valve, and the throttle valve respectively satisfy formula (9):

[0068]

[0069] Among them, K a is the signal amplifier gain, unit A / V, I(s) is the signal amplifier output current, 2A, U(s) is the analog voltage signal converted from the digital controller, 10V, Y(s) is the no-load flow rate of the electro-hydraulic proportional valve, unit m 3 / s,K v 0.6×10 -3 , s is the sensor sampling period, f is the frequency, which is 87rad / s, η is the damping ratio, usually 0.5 to 0.7, δ(s) is the displacement sensor gain, the unit is V / m, Y pod is the displacement of the throttle valve piston actuator, U c is the feedback voltage, 5V.

[0070] According to the characteristics of the electro-hydraulic proportional valve, its inlet and outlet flow equations can be obtained, namely formula (10):

[0071]

[0072] Then, based on the conservation of mass at the inlet and outlet of the electro-hydraulic proportional valve and the force balance between the throttle valve and the actuator structure of the hydraulic cylinder inside the throttle valve, the load flow equations for the throttle valve when moving in the positive and negative directions are obtained. Among them, the load flow equation for the throttle valve when moving in the positive direction is: The load flow equation when the throttle valve moves negatively is: After unifying and linearizing the load flow equations when the throttle valve moves in the positive and negative directions, the load flow equation can be obtained, namely formula (11):

[0073] Q v =δ Q Lv -δ p P v ; (11)

[0074] Among them, Q in is the inlet flow rate of the electro-hydraulic proportional valve, Q out is the outlet flow of the electro-hydraulic proportional valve, C Q is the flow coefficient of the throttle port of the electro-hydraulic proportional valve, which is taken as 0.5, ΔA is the throttle window area gradient of the electro-hydraulic proportional valve, L v is the valve core displacement, unit is m, ρ is the hydraulic oil density, unit is kg / m 3 , P s is the system input pressure, unit MPa, P v It is the difference between the pressure on the left and right sides of the throttle valve power mechanism piston, unit MPa, P R Q is the pressure on the right side of the throttle valve power mechanism piston, unit: MPa v is the load flow of the electro-hydraulic proportional valve, unit: m 3 / s, δ Q is the forward movement coefficient of the electro-hydraulic proportional valve, Unit: m 2 / s, δ p is the negative movement coefficient of the electro-hydraulic proportional valve, unit: m 4 s / kg,

[0075] Based on the working characteristics of the hydraulic cylinder and combined with the continuity equation, the hydraulic cylinder oil inlet chamber equation, the oil return chamber equation and the change in the hydraulic cylinder volume can be obtained, namely formula (12) to formula (14):

[0076] Q in -C ic (P L -P R )-C ec P L =(dV L / dt)+(V L / β e )*(dP L / dt); (12)

[0077] C ic (P L -P R )-C ec P R -Q out =(dV R / dt)+(V R / β e )*(dP R / dt); (13)

[0078] dV / dt=d(V0+y) / dt=A*dy / dt; (14)

[0079] Based on Newton's second law, while ignoring the influence of nonlinear loads such as hydraulic oil friction and the quality of hydraulic oil, the mechanical equation of the hydraulic cylinder controlling the throttle valve can be obtained. Then, the flow equation and load flow equation of the hydraulic cylinder when the throttle valve moves in the positive and negative directions, as well as the force balance equation of the throttle valve, can be obtained. Then, Laplace transform of the obtained equations can be obtained to obtain formulas (15) to (17):

[0080] Q v (s) = δ Q L v (s)-δ p P v (s); (15)

[0081] Q v (s)=AsY+(C ic +1 / 2C ec +V*s / (4β e ))P v ; (16)

[0082] P v (s)=((ms 2 +ζs+K)Y(s)+F d ) / A; (17)

[0083] Among them, Q in is the inlet flow rate of the electro-hydraulic proportional valve, Q out is the outlet flow of the electro-hydraulic proportional valve, P L is the pressure on the left side of the throttle valve power mechanism piston, P R is the pressure on the right side of the throttle valve power mechanism piston, C ic is the leakage coefficient of the hydraulic cylinder, C ec is the external leakage coefficient of the hydraulic cylinder, V L is the volume of the hydraulic cylinder oil inlet chamber, m 3 , β e V is the effective bulk elastic modulus of the hydraulic oil, MPa R is the volume of the hydraulic cylinder oil return chamber, m 3 , V is the volume inside the hydraulic cylinder, m 3 , V0 is the initial volume of the oil inlet chamber and oil return chamber of the hydraulic cylinder, m 3 , m is the total mass of the actuator, kg, s is the sensor sampling period, ζ is the viscous damping coefficient, K is the spring stiffness, N / m, F d is the force exerted by drilling fluid on the throttle valve core, P vis the difference between the pressure on the left and right sides of the throttle valve power mechanism piston, MPa, A is the effective area of ​​the hydraulic oil pre-acting on the piston, m 2 , y and Y are the displacement of the throttle valve core, m, Q v is the load flow of the electro-hydraulic proportional valve, and Y(s) is the no-load flow of the electro-hydraulic proportional valve.

[0084] According to automatic control theory, the superposition principle can be applied. Therefore, the transfer function with the displacement of the electro-hydraulic proportional valve as input and the displacement of the hydraulic cylinder as output, as well as the transfer function with the force applied to the throttle valve as input and the displacement of the hydraulic cylinder as output, are first calculated. Then, the transfer function of the well control equipment is determined by the superposition principle, that is, formula (1):

[0085]

[0086] Among them, G(s) is the opening control signal, δ Q is the forward movement coefficient of the electro-hydraulic proportional valve, δ p is the negative movement coefficient of the electro-hydraulic proportional valve, A is the effective area of ​​the hydraulic oil acting on the piston, s is the sampling period, C ec is the external leakage coefficient of the hydraulic cylinder, C ic is the leakage coefficient in the hydraulic cylinder, β e is the effective bulk elastic modulus of the hydraulic oil, L v is the displacement of the throttle valve core, V is the volume of the hydraulic cylinder, F d is the force exerted by the drilling fluid on the throttle valve core, and m is the total mass of the hydraulic cylinder actuator.

[0087] In summary, compared with the existing technology, the technical solution provided by this application has the following advantages:

[0088] 1) According to the set fitness function, the present application can adjust the parameters of the PID controller through the dung beetle optimization algorithm to achieve automatic control under different construction conditions, effectively solving the problems of low control accuracy and poor robustness of the PID controller in nonlinear control.

[0089] 2) It can control the actual wellhead pressure to approximately reach the target wellhead pressure in a short period of time without relying on the engineer's on-site experience, which can significantly reduce the control time and has broad application prospects.

[0090] 3) By dynamically adjusting the throttle valve opening, the bottom hole pressure is controlled to always be within the safe density window, reducing the possibility of serious accidents such as overflow and blowout in the well, and ensuring the safety of drilling operations.

[0091] An embodiment of the present application also provides a processor configured to execute the above-mentioned method for controlling bottom hole pressure.

[0092] Specifically, in an embodiment of the present application, the processor can be configured to: obtain the actual wellhead pressure and the target wellhead pressure; adjust the parameters of the pre-built PID controller through the dung beetle optimization algorithm according to the actual wellhead pressure and the target wellhead pressure to obtain the control quantity output by the PID controller; determine the opening control signal of the throttle valve in the well control equipment according to the control quantity based on the transfer function of the predetermined well control equipment; adjust the opening of the throttle valve through the opening control signal to achieve control of the bottom hole pressure.

[0093] In one embodiment, the processor is further configured to: initialize the current position of each dung beetle in the swarm of dung beetles; obtain the fitness function of the dung beetle optimization algorithm; determine the fitness value of each dung beetle at the current position based on the fitness function, the actual wellhead pressure and the target wellhead pressure; update the target dung beetle based on the fitness value of each dung beetle at the current position; update the current position of each dung beetle, and return to execute the step of determining the fitness value of each dung beetle at the current position based on the fitness function, until the number of executions reaches a preset number of iterations, so as to determine the proportional parameter, integral parameter and differential parameter of the PID controller according to the current position of the target dung beetle.

[0094] In one embodiment, the processor is further configured to: compare the fitness values ​​of the dung beetles at their current positions, and update the dung beetle with the largest fitness value as the target dung beetle.

[0095] In one embodiment, the processor is further configured to: determine the type corresponding to each dung beetle; determine a position update method for each dung beetle according to the type; and update the current position of each dung beetle according to the position update method.

[0096] In one embodiment, the transfer function of the well control equipment satisfies formula (1):

[0097]

[0098] Among them, G(s) is the opening control signal, δ Q is the forward movement coefficient of the electro-hydraulic proportional valve, δ p is the negative movement coefficient of the electro-hydraulic proportional valve, A is the effective area of ​​the hydraulic oil acting on the piston, s is the sampling period, C ec is the external leakage coefficient of the hydraulic cylinder, C ic is the leakage coefficient in the hydraulic cylinder, β e is the effective bulk elastic modulus of the hydraulic oil, L v is the displacement of the throttle valve core, V is the volume of the hydraulic cylinder, F d is the force exerted by the drilling fluid on the throttle valve core, and m is the total mass of the hydraulic cylinder actuator.

[0099] The above technical solution first adjusts the parameters of the pre-built PID controller based on the actual wellhead pressure and target wellhead pressure obtained using the dung beetle optimization algorithm to obtain the control quantity output by the PID controller. Then, based on the transfer function of the predetermined well control equipment, the opening control signal of the throttle valve in the well control equipment is determined according to the control quantity. The opening of the throttle valve is then adjusted by the opening control signal to achieve control of the bottomhole pressure. This application uses the dung beetle optimization algorithm to adjust the parameters of the pre-built PID controller based on the actual wellhead pressure and target wellhead pressure obtained. It can adjust the parameters of the PID controller in real time under different construction conditions, reduce the impact of the nonlinear characteristics of the throttle valve on the PID control, and thus improve the control accuracy of the bottomhole pressure.

[0100] Figure 2 The schematic diagram of a system for controlling bottom hole pressure according to an embodiment of the present application is shown. Figure 2 As shown, an embodiment of the present application further provides a system for controlling bottom hole pressure, comprising: a processor (not shown in the figure); a PID controller 210; and a well control device 220, including a throttle valve 224.

[0101] Specifically, the system for controlling bottomhole pressure may include a processor, a PID controller 210, well control equipment 220, and a pressure sensor 230. The processor can obtain the target wellhead pressure and the actual wellhead pressure detected by the pressure sensor 230, and adjust the proportional, integral, and differential parameters of the PID controller 210 using the dung beetle optimization algorithm. This allows the PID controller 210 to determine the output control variable. The processor can determine an aperture control signal based on the transfer function and control variable of the well control equipment 220, and input the aperture control signal into the well control equipment 220 to adjust the aperture of the throttle valve 224 in the well control equipment 220, thereby controlling the bottomhole pressure. Different apertures of the throttle valve 224 will change the actual wellhead pressure. The actual wellhead pressure can be obtained using the pressure sensor 230 and fed back to the processor, forming a closed-loop control loop.

[0102] Continue as Figure 2 As shown, in the embodiment of the present application, the well control equipment may further include: a signal amplifier; and an electro-hydraulic proportional valve.

[0103] Specifically, well control equipment 220 includes a signal amplifier 221, an electro-hydraulic proportional valve 222, a hydraulic pipeline 223, and a throttle valve 224. After the opening control signal is determined, the opening control signal passes through signal amplifier 221 and electro-hydraulic proportional valve 222 in sequence. This causes electro-hydraulic proportional valve 222 to pump hydraulic oil into hydraulic pipeline 223 based on the opening control signal amplified by signal amplifier 221, thereby changing the displacement of the piston of throttle valve 224 and adjusting the opening of throttle valve 224.

[0104] An embodiment of the present application further provides a machine-readable storage medium having stored thereon instructions for causing a machine to execute the above-mentioned method for controlling bottom hole pressure.

[0105] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0106] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0107] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0108] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0109] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0110] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0111] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0112] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0113] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for controlling bottom hole pressure, characterized in that: include: Obtain actual wellhead pressure and target wellhead pressure; According to the actual wellhead pressure and the target wellhead pressure, parameters of a pre-built PID controller are adjusted by a dung beetle optimization algorithm to obtain a control variable output by the PID controller, wherein the parameters of the PID controller include a proportional parameter, an integral parameter, and a differential parameter; Based on a predetermined transfer function of the well control equipment, determining an opening control signal of a throttle valve in the well control equipment according to the control variable; The opening of the throttle valve is adjusted by the opening control signal to achieve control of the bottom hole pressure; The step of adjusting the parameters of the pre-built PID controller by using a dung beetle optimization algorithm according to the actual wellhead pressure and the target wellhead pressure includes: Initialize the current position of each dung beetle in the swarm; Obtaining a fitness function of the dung beetle optimization algorithm; determining the fitness value of each dung beetle at the current position according to the fitness function, the actual wellhead pressure and the target wellhead pressure; Comparing the fitness values ​​of the dung beetles at their current positions, and updating the dung beetle with the largest fitness value as the target dung beetle; Determining the type corresponding to each dung beetle, determining a position update method for each dung beetle according to the type, updating the current position of each dung beetle according to the position update method, and returning to execute the step of determining the fitness value of each dung beetle at the current position according to the fitness function until the number of executions reaches a preset number of iterations, so as to determine the proportional parameter, integral parameter, and differential parameter of the PID controller according to the current position of the target dung beetle; The well control equipment further includes a signal amplifier and an electro-hydraulic proportional valve. The transfer function of the well control equipment is determined by: respectively acquiring component control functions of the signal amplifier, the electro-hydraulic proportional valve, and the throttle valve; determining a transfer function of the well control equipment according to component control functions of the signal amplifier, the electro-hydraulic proportional valve, and the throttle valve; The transfer function of the well control equipment satisfies formula (1): ；（1） in, is the opening control signal, is the forward movement coefficient of the electro-hydraulic proportional valve, is the negative movement coefficient of the electro-hydraulic proportional valve, is the effective area of ​​the hydraulic oil acting on the piston, is the sampling period, is the external leakage coefficient of the hydraulic cylinder, is the leakage coefficient in the hydraulic cylinder, is the effective bulk modulus of the hydraulic oil, is the throttle valve core displacement, is the volume of the hydraulic cylinder, is the force exerted by the drilling fluid on the throttle valve core, is the total mass of the hydraulic cylinder actuator.

2. A processor, characterized in that: The device is configured to perform the method for controlling bottom hole pressure according to claim 1.

3. A system for controlling bottom hole pressure, characterized in that: include: The processor according to claim 2; PID controller; as well as well control equipment, including choke valves; signal amplifier; Electro-hydraulic proportional valve.

4. A machine-readable storage medium, characterized in that The machine-readable storage medium stores instructions for causing a machine to execute the method for controlling bottom hole pressure according to claim 1 .

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