Control method, device, processor and storage medium for cementing operations

Abstract

Embodiments of the present application provide a control method and device for cementing operation, a processor and a storage medium, and belong to the technical field of oil and gas drilling. The control method for cementing operation comprises the following steps: obtaining relevant data of cementing operation; predicting a target pressure curve of wellhead pressure changing with time according to the relevant data based on a preset pressure prediction model; adjusting parameters of a PID controller according to the target pressure curve to obtain a PID controller with set parameters; and controlling the wellhead pressure by the PID controller with set parameters so that the bottom hole pressure continuously stays within a safe pressure window. The embodiments of the present application can reduce errors.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling technology, and more specifically to a control method, device, processor, and storage medium for cementing operations. Background Technology

[0002] With the increasing demand for oil and gas resources, oil and gas extraction is gradually moving towards deeper and ultra-deep wells. As well depth increases, the construction process increasingly faces challenges such as high temperature and pressure, narrow density windows, narrowing wellbore flow channels, and long open-hole sections. These increasingly complex construction conditions bring new challenges to cementing operations. For cementing in complex formations, overflows are highly likely to occur under pressure. Furthermore, excessive pressure increases during construction can lead to downhole leakage. All of these factors can cause cementing failure, posing significant risks to the cementing process. Current technology typically employs manual adjustment, specifically manually adjusting the choke valve pressure to keep the bottom hole pressure within a safe pressure window. However, manual adjustment is prone to significant errors. Summary of the Invention

[0003] The purpose of this invention is to provide a control method, device, processor, and storage medium for cementing operations to solve the problem of large errors in the prior art.

[0004] To achieve the above objectives, a first aspect of the present invention provides a control method for cementing operations, the control method comprising:

[0005] Obtain relevant data for cementing operations;

[0006] Based on a preset pressure prediction model, the target pressure curve of wellhead pressure changing over time is predicted according to relevant data.

[0007] Adjust the parameters of the PID controller according to the target pressure curve to obtain the PID controller with the parameters tuned.

[0008] The wellhead pressure is controlled by a PID controller with tuned parameters to keep the bottom hole pressure within a safe pressure window.

[0009] In this embodiment of the invention, based on a preset pressure prediction model, a target pressure curve for wellhead pressure changing over time is predicted according to relevant data, including: determining a first curve for fluid column pressure changing over time and a second curve for circulating friction changing over time according to relevant data, wherein the relevant data includes the vertical height of the fluid column changing over time; and determining the target pressure curve according to the first curve, the second curve, and the preset target bottom hole pressure.

[0010] In this embodiment of the invention, the relevant data also includes the fluid density of the liquid column; determining a first change curve of the liquid column pressure over time based on the relevant data includes determining the liquid column pressure according to the following formula (1):

[0011]

[0012] Among them, P l ρ is the pressure of the liquid column. i Let g be the fluid density of the i-th segment of the liquid column, g be the acceleration due to gravity, and h be the velocity of the liquid. i Let be the vertical height of the i-th liquid column.

[0013] In this embodiment of the invention, the relevant data also includes the friction coefficient of the liquid column, the average flow velocity of the liquid column, the fluid density of the liquid column, and the equivalent diameter of the liquid column; the second variation curve of the cyclic friction over time is determined based on the relevant data, including determining the cyclic friction according to the following formula (2):

[0014]

[0015] Among them, P f For cyclic friction, f i Let ρ be the friction coefficient of the i-th segment of the liquid column. i Let v be the fluid density of the i-th liquid column. i Let D be the average flow velocity of the i-th liquid column. hy h is the equivalent diameter of the liquid column. i Let be the vertical height of the i-th liquid column.

[0016] In this embodiment of the invention, adjusting the parameters of the PID controller according to the target pressure curve to obtain the PID controller with tuned parameters includes: adjusting the parameters of the PID controller according to the target pressure curve based on a trial-and-error method to obtain the PID controller with tuned parameters.

[0017] In this embodiment of the invention, the parameters of the PID controller are adjusted according to the target pressure curve based on the trial-and-error method to obtain the PID controller with tuned parameters. This includes: adjusting the parameters of the PID controller according to the target pressure curve based on the trial-and-error method and a preset PID parameter range to obtain the PID controller with tuned parameters.

[0018] In this embodiment of the invention, the relevant data also includes flow rate; the control method further includes: adjusting the opening of the throttle valve to change the flow rate when the bottom hole pressure is not within the safe pressure window, so as to obtain the adjusted relevant data; based on the preset pressure prediction model, redetermining the adjusted target pressure curve according to the adjusted relevant data; readjusting the parameters of the PID controller according to the adjusted target pressure curve to obtain the PID controller with retuned parameters; controlling the wellhead pressure through the PID controller with retuned parameters so that the bottom hole pressure remains within the safe pressure window.

[0019] A second aspect of the present invention provides a processor configured to execute the control method for cementing operations described above.

[0020] A third aspect of the present invention provides a control device for cementing operations, the control device comprising:

[0021] The data acquisition module is used to acquire relevant data for cementing operations;

[0022] The pressure prediction module is used to predict the target pressure curve of wellhead pressure over time based on a preset pressure prediction model and relevant data.

[0023] The parameter adjustment module is used to adjust the parameters of the PID controller according to the target pressure curve to obtain the PID controller after parameter tuning.

[0024] The pressure control module is used to control the wellhead pressure through a PID controller with tuned parameters, so that the bottom hole pressure remains within a safe pressure window.

[0025] A fourth aspect of the present invention provides a machine-readable storage medium on which a program or instruction is stored, which, when executed by a processor, implements the control method for cementing operations described above.

[0026] The above technical solution acquires relevant data from cementing operations and, based on a preset pressure prediction model, predicts the target pressure curve of the wellhead pressure over time. The parameters of the PID controller are then adjusted according to this target pressure curve to obtain a tuned PID controller. This tuned PID controller controls the wellhead pressure, ensuring the bottomhole pressure remains within a safe pressure window. This solution eliminates the need for manual adjustment to control pressure during cementing operations, effectively replacing manual pressure control, reducing errors caused by manual operation, and achieving automated wellhead pressure control. The PID controller enables closed-loop precise pressure control, improving the success rate of cementing operations, significantly reducing cementing costs, minimizing safety accidents, and achieving safe and efficient cementing operations.

[0027] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0028] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 The schematic diagram illustrates a flow chart of a control method for cementing operations according to an embodiment of the present invention;

[0030] Figure 2 The schematic diagram illustrates a flow chart of a control method for cementing operations according to another embodiment of the present invention;

[0031] Figure 3 This illustration schematically shows a mesh generation diagram during the solution process of a cementing wellbore pressure prediction model in one embodiment of the present invention;

[0032] Figure 4 This schematically illustrates a flowchart of the calculation of the back pressure application value at the cement injection wellhead, which incorporates a manual control step in one embodiment of the present invention.

[0033] Figure 5(a) schematically shows a comparison curve of the predicted pressure value and the control pressure value when the proportional parameter is 0.02 in one embodiment of the present invention;

[0034] Figure 5(b) schematically shows a comparison curve of the predicted pressure value and the control pressure value when the proportional parameter is 0.2 in one embodiment of the present invention;

[0035] Figure 5(c) schematically shows a comparison curve of the predicted pressure value and the control pressure value when the proportional parameter is 1 in one embodiment of the present invention;

[0036] Figure 6(a) schematically shows a comparison curve of the predicted pressure value and the control pressure value when the integral parameter is 2 in one embodiment of the present invention;

[0037] Figure 6(b) schematically shows a comparison curve of the predicted pressure value and the control pressure value when the integral parameter is 0.2 in one embodiment of the present invention;

[0038] Figure 6(c) schematically shows a comparison curve of the predicted pressure value and the control pressure value when the integral parameter is 0.02 in one embodiment of the present invention;

[0039] Figure 7 The diagram illustrates the change of simulated bottom hole pressure over time in one embodiment of the present invention.

[0040] Figure 8 The schematic diagram illustrates a structural block diagram of a control device for cementing operations according to an embodiment of the present invention. Detailed Implementation

[0041] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0042] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0043] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0044] Figure 1 The diagram illustrates a flow chart of a control method for cementing operations according to an embodiment of the present invention. Figure 1 As shown, in this embodiment of the invention, a control method for cementing operations is provided. Taking the application of this control method to a processor as an example, the control method may include the following steps:

[0045] Step S102: Obtain relevant data for cementing operations.

[0046] Step S104: Based on the preset pressure prediction model, predict the target pressure curve of wellhead pressure changing with time according to relevant data.

[0047] Step S106: Adjust the parameters of the PID controller according to the target pressure curve to obtain the PID controller with the parameters tuned.

[0048] Step S108: The wellhead pressure is controlled by the PID controller with calibrated parameters so that the bottom hole pressure remains within the safe pressure window.

[0049] It is understood that data related to cementing operations can include wellbore structural parameters, casing string structure, casing formation three-pressure profile, formation physical properties, and cementing operation plans. Wellbore structural parameters can include well depth, annular clearance, and open-hole length, while cementing operation plans can include cementing methods, cementing procedures, annular slurry column structure, displacement rate, displacement flow regime, drilling fluid performance parameters, cement slurry performance parameters, and pre-flush fluid performance parameters. The preset pressure prediction model is a pre-trained model capable of predicting wellhead pressure. The input to this model is the relevant parameters of the cementing operation, and the output is a wellhead pressure variation curve, i.e., a curve showing the change in wellhead pressure over time, with values ​​representing the changes in wellhead pressure at different times. The target pressure curve is the ideal wellhead pressure variation curve corresponding to the relevant data of the cementing operation. Wellhead pressure is the fluid pressure corresponding to the annular space at the wellhead location, i.e., wellhead back pressure. Bottomhole pressure is the fluid pressure corresponding to the annular space at the bottom of the well. Understandably, the term "PID controller" here is a general term, meaning that the PID controller in this embodiment of the invention can be any combination or single use of proportional control, integral control, and derivative control. Specifically, the PID controller in this embodiment can be composed of at least one of a proportional unit (P), an integral unit (I), and a derivative unit (D), thereby obtaining the tuned PID controller by adjusting at least one of the three parameters: proportional parameter Kp, integral parameter Ki, and derivative parameter Kd. The safe pressure window is a pre-set threshold range for bottom hole pressure, including an upper safe pressure threshold and a lower safe pressure threshold.

[0050] Specifically, the processor can acquire relevant data from cementing operations, such as data input by the user or pre-stored data. Based on a preset pressure prediction model, the processor can predict the target pressure curve of the wellhead pressure over time, and then adjust the parameters of the PID controller (including at least one of the proportional parameter Kp, integral parameter Ki, and derivative parameter Kd) according to the target pressure curve. This results in a tuned PID controller, where the parameters are adjusted to make the pressure curve of the wellhead pressure over time as close as possible to the target pressure curve. Specific methods for tuning the PID controller parameters include, but are not limited to, trial and error, attenuation curve methods, critical proportional gain methods, and theoretical tuning methods. Furthermore, the processor can control the wellhead pressure through the tuned PID controller to ensure that the bottomhole pressure remains within a safe pressure window. In other words, by adjusting the wellhead pressure through the tuned PID controller, the bottomhole pressure can be guaranteed to remain within a safe pressure window.

[0051] The aforementioned control method for cementing operations acquires relevant data from the cementing operation and, based on a preset pressure prediction model, predicts the target pressure curve of the wellhead pressure over time. The parameters of the PID controller are then adjusted according to this target pressure curve to obtain a tuned PID controller. This tuned PID controller then controls the wellhead pressure, ensuring the bottomhole pressure remains within a safe pressure window. This technical solution obtains the target pressure curve of the wellhead pressure over time through a pressure prediction model, allowing for PID controller parameter tuning. The tuned PID controller then controls the wellhead pressure, ensuring the bottomhole pressure remains within a safe pressure window. This solution eliminates the need for manual adjustment to achieve pressure control in cementing operations, effectively replacing manual pressure control, reducing errors caused by manual operation, and achieving automated wellhead pressure control. The PID controller enables closed-loop precise pressure control, improving the success rate of cementing operations, significantly reducing cementing costs, minimizing safety accidents, and achieving the goal of safe and efficient cementing operations.

[0052] In one embodiment, based on a preset pressure prediction model, predicting a target pressure curve for wellhead pressure changes over time according to relevant data includes: determining a first curve for fluid column pressure changes over time and a second curve for circulating friction changes over time according to relevant data, wherein the relevant data includes the vertical height of the fluid column that changes over time; and determining the target pressure curve based on the first curve, the second curve, and the preset target bottom hole pressure.

[0053] The first curve represents the change in liquid column pressure over time. Liquid column pressure is the pressure generated by the weight of the liquid column itself. Understandably, during cementing operations, i.e., the injection of cement into the well, the liquid column pressure is related to the vertical height of the liquid column. Since the vertical height of the liquid column in the well changes over time, the liquid column pressure also changes over time. The first curve can be obtained based on the liquid column pressure at different times. The second curve represents the change in circulating friction over time. Similarly, during cementing operations, i.e., the injection of cement into the well, circulating friction is related to the vertical height of the liquid column. Since the vertical height of the liquid column in the well changes over time, the circulating friction also changes over time. The second curve can be obtained based on the circulating friction at different times. The vertical height of the liquid column that changes over time can be determined in advance based on other relevant data from the cementing operation (e.g., displacement rate). The preset target bottom hole pressure is a pre-set expected value for bottom hole pressure.

[0054] Specifically, the processor can determine the first curve of liquid column pressure changing with time and the second curve of circulating friction changing with time based on relevant data (including the vertical height of the liquid column changing with time). Then, based on the first curve, the second curve, and the preset target bottom hole pressure, the target pressure curve can be determined. Understandably, based on the bottom hole constant pressure method, it is known that the sum of the wellhead pressure, liquid column pressure, and circulating friction is equal to the target bottom hole pressure. Therefore, after knowing the target bottom hole pressure, the first curve representing the liquid column pressure, and the second curve representing the circulating friction, the wellhead pressure at different times can be obtained by calculating the difference between the target bottom hole pressure, the liquid column pressure, and the circulating friction, thereby obtaining the target pressure curve of wellhead pressure changing with time.

[0055] In one embodiment, the relevant data also includes the fluid density of the liquid column; determining a first curve of the liquid column pressure changing over time based on the relevant data includes determining the liquid column pressure according to the following formula (1):

[0056]

[0057] Among them, P l ρ is the pressure of the liquid column. i Let g be the fluid density of the i-th segment of the liquid column, g be the acceleration due to gravity, and h be the velocity of the liquid. i Let be the vertical height of the i-th liquid column.

[0058] It is understood that the pressure of the liquid column is also related to the fluid density of the liquid column, which can be determined in advance. Furthermore, in some embodiments, the fluid density of different segments of the liquid column can be the same or different, depending on the fluid-related parameters in the cementing operation.

[0059] Specifically, the processor can obtain the liquid column pressure at different times based on the above formula (1) and relevant data of the cementing operation (including the fluid density of the liquid column and the vertical height of the liquid column), thereby obtaining the first change curve of the liquid column pressure over time.

[0060] In one embodiment, the relevant data also includes the friction coefficient of the liquid column, the average flow velocity of the liquid column, the fluid density of the liquid column, and the equivalent diameter of the liquid column; a second curve of the cyclic friction versus time is determined based on the relevant data, including determining the cyclic friction according to the following formula (2):

[0061]

[0062] Among them, P f For cyclic friction, f i Let ρ be the friction coefficient of the i-th segment of the liquid column. i Let v be the fluid density of the i-th liquid column. i Let D be the average flow velocity of the i-th liquid column. hy h is the equivalent diameter of the liquid column. i Let be the vertical height of the i-th liquid column.

[0063] It is understandable that circulating friction is related to the friction coefficient of the liquid column, the fluid density of the liquid column, the average flow velocity of the liquid column, the equivalent diameter of the liquid column, and the vertical height of the liquid column. These parameters can be obtained directly from relevant data of cementing operations or inferred from them. Among them, the friction coefficient, fluid density, and average flow velocity of each segment of the liquid column are related to the fluid-related parameters in the relevant parameters of cementing operations.

[0064] Specifically, the processor can obtain the circulating friction at different times based on the above formula (2) and relevant data of cementing operation (including the friction coefficient of the liquid column, the fluid density of the liquid column, the average flow velocity of the liquid column, the equivalent diameter of the liquid column and the vertical height of the liquid column), thereby obtaining the second curve of the circulating friction changing with time.

[0065] In one embodiment, adjusting the parameters of the PID controller according to the target pressure curve to obtain the PID controller with tuned parameters includes: adjusting the parameters of the PID controller according to the target pressure curve based on a trial-and-error method to obtain the PID controller with tuned parameters.

[0066] Specifically, the processor can adjust the parameters of the PID controller based on the target pressure curve using a trial-and-error method. That is, it adjusts the proportional, integral, and derivative parameters in a certain step until a parameter combination that meets the field requirements is tuned. The overall adjustment can follow the principle of proportional first, then integral, and finally derivative. After each adjustment, the bottom hole pressure is simulated to determine whether the bottom hole pressure is within the safe pressure window. If the bottom hole pressure is within the safe pressure window, it means that the PID parameter combination meets the field requirements, thus obtaining the PID controller after parameter tuning.

[0067] In one embodiment, adjusting the parameters of the PID controller according to the target pressure curve based on a trial-and-error method to obtain a PID controller with tuned parameters includes: adjusting the parameters of the PID controller according to the target pressure curve based on a trial-and-error method and a preset PID parameter range to obtain a PID controller with tuned parameters.

[0068] It can be understood that the preset PID parameter range is the reference value range of the pre-set PID control parameters (including proportional parameters, integral parameters, and derivative parameters).

[0069] Specifically, when the processor adjusts the parameters of the PID controller using a trial-and-error method, it can integrate the PID parameters based on the target pressure curve according to the preset PID parameter range to obtain the PID controller with the parameters tuned.

[0070] In one embodiment, the relevant data further includes flow rate; the control method further includes: adjusting the opening of the throttle valve to change the flow rate when the bottom hole pressure is not within the safe pressure window, so as to obtain the adjusted relevant data; based on a preset pressure prediction model, redetermining the adjusted target pressure curve according to the adjusted relevant data; readjusting the parameters of the PID controller according to the adjusted target pressure curve to obtain the PID controller with retuned parameters; controlling the wellhead pressure through the PID controller with retuned parameters so that the bottom hole pressure remains within the safe pressure window.

[0071] It is understandable that data related to cementing operations can include the flow rate of fluids in the well and the positive correlation between the opening of the choke valve and the wellhead pressure.

[0072] Specifically, when the bottom hole pressure is not within the safe pressure window, the processor can adjust the opening of the throttle valve to change the flow velocity of the fluid in the well, thereby obtaining adjusted relevant data (including flow velocity). Based on a preset pressure prediction model, the processor can then redetermine the adjusted target pressure curve using this data. The PID controller parameters are then readjusted according to this target pressure curve to obtain a retuned PID controller. This retuned PID controller controls the wellhead pressure, ensuring that the bottom hole pressure remains within the safe pressure window. Furthermore, the throttle valve opening can also be adjusted manually.

[0073] A specific embodiment of this invention provides a control method for cementing operations, mainly involving the prediction of wellbore pressure and the automatic control of wellhead back pressure during pressure-controlled cementing. From a prediction perspective, the differences in density, rheological properties, and injection volume among different injected fluids during cementing significantly increase the amplitude and frequency of wellbore pressure variations. From a control perspective, the complex changes in wellbore pressure increase the difficulty of wellhead back pressure control, making manual control challenging.

[0074] The technical solution provided by this invention can predict the wellbore pressure during cementing and automatically control the wellhead back pressure according to the pressure balance principle. It is mainly based on the cementing field data and cementing scheme, using the cementing pressure prediction model to obtain the wellhead back pressure change curve over time, and using the trial and error method to determine the parameter combination of the PID controller, thereby realizing the automatic real-time precise adjustment of the wellhead back pressure.

[0075] Specifically, an automatic pressure-controlled cementing wellbore pressure prediction model was first established. The cementing pump program was input to obtain the wellhead back pressure variation curve over time. Based on the analysis of the wellhead back pressure variation pattern, the optimal PID controller parameters were tuned using a trial-and-error method (a method of adjusting based on changes in the controlled parameter). This enabled real-time automatic adjustment of the wellhead back pressure during cementing operations.

[0076] To achieve the above objectives, this invention provides an automatic pressure-controlled cementing method for well cementing based on a PID controller, which includes the following steps in sequence (see flowchart). Figure 2 ):

[0077] Step 1: Collect field data and determine the cementing plan for predicting wellbore pressure during cementing. Field data includes: wellbore structure (well depth, annular clearance, open hole length, etc.), casing string structure, three-pressure profile of the casing formation, formation physical parameters, etc. The cementing plan includes: cementing method, cementing construction process, annular slurry string structure, displacement rate, displacement flow regime, drilling fluid performance parameters, cement slurry performance parameters, and pre-flush fluid performance parameters, etc.

[0078] Step 2: Based on the parameters in Step 1, use the controlled pressure cementing wellbore pressure prediction model (including the formula for the bottom hole constant pressure method) to obtain the curve of wellhead back pressure changing over time.

[0079] Step 3: Based on the wellhead back pressure variation curve over time, and referring to the values ​​given in Table 1, determine the optimal PID controller parameter combination, including the proportional parameter K, using a trial-and-error method (a method of adjusting based on changes in the controlled parameter). P Integral parameter K I and differential parameter K D .

[0080] Step 4: Based on the calibrated PID controller parameter combination and the target wellhead back pressure, simulate the actual adjusted wellhead back pressure during cement injection, and simultaneously simulate the bottom pressure of the cement injection well to determine whether the bottom pressure is always within the safe pressure window.

[0081] Step 5: If the simulated bottom hole pressure is always within the safe pressure window, the wellhead back pressure control during the automatic pressure control cementing process is completed solely by the PID controller; if the simulated bottom hole pressure exceeds the safe pressure window, the throttle valve opening is manually adjusted (the valve opening and wellhead back pressure are positively correlated), and the process returns to Step 3 to readjust the PID parameters based on the new target pressure curve.

[0082] Table 1 Reference PID Control Parameters

[0083]

[0084] The above is the main process of the automated pressure controlled cementing method. The following is a supplementary description of the model content for each step:

[0085] First, we introduce the wellbore pressure prediction model for controlled-pressure cementing. This model can not only predict the annular pressure during controlled-pressure cementing, but also, based on the bottom-hole constant pressure method, obtain the wellhead back pressure variation curve over time using the prediction results.

[0086] Annular pressure consists of three parts: hydraulic column pressure, circulating friction, and wellhead back pressure. When the target location is the bottom of the well, the annular pressure is the bottom-hole pressure, which is the control target during cementing. Wellhead back pressure is an adjustable parameter, while hydraulic column pressure and circulating friction are calculated. The principle of pressure-controlled cementing is to accurately calculate the hydraulic column pressure and annular friction, and then adjust the wellhead back pressure to ensure that the bottom-hole pressure is within a safe pressure window. The specific formula is as follows:

[0087] P a =P b +P l +P f(1)

[0088] P b =P a -P l -P f (2)

[0089] Among them, P a This is the target bottom hole pressure, and the unit can be MPa; P b This refers to the wellhead back pressure, which can be measured in MPa; P l This is the pressure of the liquid column, and the unit can be MPa; P f It refers to cyclic friction, and the unit can be MPa.

[0090] The key to calculating liquid column pressure is obtaining the distribution of the annular slurry column structure in real time. For example... Figure 3 As shown, the annulus is segmented according to the fluid type, and the pressure of the annular liquid column is calculated segment by segment and then summed. The specific formula is as follows:

[0091]

[0092] Where, ρ i This is the fluid density of the i-th segment, in g / m³. 3 g is the acceleration due to gravity, with units of m / s². 2 h i It is the vertical height of the i-th segment of the liquid column, in meters (m).

[0093] The calculation of circulatory friction is quite complex, as annular temperature, different fluid flow regimes, and fluid rheological modes all affect the magnitude of friction. Similar to the calculation method for liquid column pressure, the annulus is segmented according to the fluid type, and the circulatory friction is calculated segment by segment and then summed.

[0094] First, calculate the Reynolds number of the fluid. Based on the Reynolds number, determine the flow regime of the fluid, and then calculate the annular friction using different formulas:

[0095]

[0096] In the formula: Re a It is the Reynolds number of the annulus fluid, dimensionless; v a D is the average velocity within the annulus, expressed in m / s. hy ρ is the annular hydraulic diameter, in meters (m); ρ is the annular fluid density, in kilograms per cubic meter (kg / m³). 3 μ ea It is the effective viscosity of the annular fluid, expressed in Pa·s.

[0097] If Re a ≤2100, calculate the annular internal friction coefficient according to formula (5):

[0098]

[0099] If Re a >2100, calculate the annular internal friction coefficient according to formula (6):

[0100]

[0101] In the formula: f a is the annular internal friction coefficient, dimensionless; a and b are coefficients, dimensionless; n a It is the generalized flowability index of the annular fluid.

[0102] Substitute the friction coefficients corresponding to different well sections into the annular friction calculation equation, calculate the annular circulating pressure loss of each well section according to formula (7), and add the circulating pressure loss of each well section to get the total annular circulating pressure loss.

[0103]

[0104] In the formula: f i v is the coefficient of friction of the i-th segment of the liquid column; i L is the average velocity of the i-th liquid column, in m / s; i D is the vertical height of the i-th segment of the liquid column, in meters. hy denoted as the equivalent diameter of the liquid column.

[0105] At high temperatures, drilling fluid exhibits an expansion effect, reducing its density; under high pressure, it exhibits a compression effect, increasing its density. During cementing in deep and ultra-deep wells, the large variations in temperature and pressure significantly impact the density of the annular fluid. The coupled effects of temperature and pressure are illustrated by mathematical equation (8):

[0106]

[0107] In the formula: ρ is the density of the fluid at temperature T and pressure p, with units of kg / m³. 3 ρ0 is the density of the fluid at standard temperature T0 and standard pressure p0, in kg / m³. 3 T represents temperature in °C; T0 represents standard temperature in °C; p represents pressure in Pa; p0 represents standard pressure in Pa; ξ p ξ pp ξ T ξ TT ξ pT The regression coefficient must be obtained experimentally, and φ is the voltage stabilization coefficient.

[0108] Based on the wellhead back pressure variation curve calculated by the cementing pressure prediction model, the curve is subjected to characteristic analysis. A trial-and-error method is used to adjust the PID parameters, specifically adjusting the proportional, integral, and derivative parameters in a specific sequence until a parameter combination that meets the field requirements is found. The parameter tuning is performed as follows:

[0109] 1. The overall adjustment follows the principle of proportional, then integral, and finally derivative. After each adjustment, the bottom hole pressure is simulated to determine if it is within the safe pressure window. If the bottom hole pressure is within the safe pressure window, it indicates that the PID parameter combination meets the field requirements. If a reasonable PID parameter cannot be tuned, a manual control element should be introduced. Figure 4 The diagram shows the automatic pressure control cementing wellbore pressure prediction process after introducing a manual control component.

[0110] 2. When adjusting the proportional parameter, set the integral parameter to ∞ and the derivative parameter to 0 to ensure the PID controller operates solely under proportional action, maximizing the contribution of proportional regulation. Adjustments should be made from small to large values, with a bottomhole pressure simulation performed after each adjustment to find the optimal proportional parameter. If the bottomhole pressure can be kept within the safe pressure window using only proportional action, then only a proportional controller is needed.

[0111] 3. Based on proportional control, the integral parameter is adjusted from large to small. After each adjustment, the bottom hole pressure is simulated to find the optimal integral parameter. If the bottom hole pressure can be kept within the safe pressure window under both proportional and integral control, a dual-acting controller (proportional and integral) is used. If this cannot meet the field requirements, a derivative controller is introduced.

[0112] 4. The method for adjusting the derivative parameter is the same as that for the integral parameter, except that the adjustment principle is to gradually increase it from 0.

[0113] The calculation method, based on the simulated bottomhole pressure variation curve using the automatically controlled wellhead back pressure value, is shown in the formula. It is determined whether the bottomhole pressure is consistently greater than the formation pore pressure and less than the formation fracturing pressure. If these conditions are met, the design scheme meets the requirements.

[0114] P 模拟井底压力 =P 控制回压 +P l +P f (9)

[0115] Among them, P 模拟井底压力 It is the bottom hole pressure value after automatic pressure control, P 控制回压 It is the automatically applied wellhead back pressure.

[0116] Furthermore, in order to better understand the invention, the invention will be described in detail below with reference to a specific embodiment.

[0117] Taking Well A in a certain block of the Sichuan Basin as an example, this well adopts a six-section wellbore structure, and the target layer is the Silurian system. During cementing, it faces challenges such as multiple regional reservoirs, coexistence of high and low pressures, and long, narrow wellbore sections, resulting in high well control safety risks and difficulty in guaranteeing cementing quality. If manual backpressure is applied at the wellhead during the injection stage, the bottom hole pressure will exceed the safe pressure window. Well A has a depth of 7800m, a formation fracture pressure of 161.9MPa, and a formation pore pressure of 158.9MPa. Controlled pressure cementing injection technology was used during on-site cementing, but manual pressure control is difficult. The parameters of the model in this embodiment are shown in Table 2. Based on the basic parameters of this embodiment, a controlled pressure cementing injection scheme is designed according to the above method.

[0118] Table 2 Basic parameters for predicting cementing pressure in Well A

[0119]

[0120]

[0121] Using the pressure prediction model, a reference control pressure value was calculated based on the aforementioned basic parameters. The bottom hole pressure was set to a constant 151 MPa, and the curves showing the change in wellhead back pressure over time were obtained, as shown in Figures 5 and 6. PID parameters were then tuned based on these predicted pressure curves.

[0122] The integral parameter was set to ∞ and the derivative parameter to 0. The proportional parameter was tuned from smallest to largest, and the control pressure curves under different proportional parameters are shown in Figure 5. As shown in Figure 5(a), when the proportional parameter is 0.02, the system response time is too long and does not meet the requirements of real-time pressure control on site. As the proportional parameter increases, the system response speed becomes faster and faster. As shown in Figure 5(c), when the proportional parameter is 1, oscillation (overshoot) occurs at the pressure inflection point. Based on comprehensive judgment, a proportional parameter of 1 is selected.

[0123] To improve the accuracy and stability of the PID controller, an integral regulator was introduced. The proportional parameter was set to 1 and the derivative parameter to 0. The proportional parameter was tuned from largest to smallest, and the control pressure curves under different integral parameters are shown in Figure 6. As shown in Figure 6(a), when the integral parameter is 2, the system exhibits oscillation, which easily causes downhole pressure fluctuations and is detrimental to maintaining constant bottomhole pressure. Both excessively large and small integral parameters will cause system oscillation. As shown in Figure 6(b), when the integral parameter is 0.2, the system is relatively stable. Based on comprehensive judgment, an integral parameter of 0.2 was selected.

[0124] After tuning the PID controller parameters, the parameter combination K was selected. p=1, K i =0.2. Based on this parameter combination, a simulation of the bottom hole pressure for automatic pressure controlled cementing was performed. The simulation results are as follows: Figure 7 As shown in the figure, during the controlled-pressure cementing stage, the bottom hole pressure changes continuously with the continuous injection of cementing fluid, but always remains within the safe pressure window. Therefore, the automatic controlled-pressure cementing method based on a PID controller proposed in this paper can effectively replace manual pressure control, achieving real-time and precise control of cementing pressure. Before cementing, the wellbore pressure during the cementing process is predicted, and automatic pressure control equipment is used to adjust the wellhead back pressure, thereby achieving closed-loop precise pressure control. Research on automatic controlled-pressure cementing technology will significantly reduce cementing costs, improve cementing quality, reduce the occurrence of accidents, and ultimately further improve the level of oil and gas drilling and completion.

[0125] This invention provides a processor configured to execute a control method for cementing operations according to the above embodiments.

[0126] like Figure 8 As shown, an embodiment of the present invention provides a control device 800 for cementing operations, the control device 800 comprising:

[0127] Data acquisition module 810 is used to acquire relevant data for cementing operations;

[0128] The pressure prediction module 820 is used to predict the target pressure curve of wellhead pressure changing over time based on a preset pressure prediction model and relevant data.

[0129] The parameter adjustment module 830 is used to adjust the parameters of the PID controller according to the target pressure curve to obtain the PID controller after parameter tuning.

[0130] The pressure control module 840 is used to control the wellhead pressure through a PID controller with tuned parameters, so that the bottom hole pressure remains within a safe pressure window.

[0131] The aforementioned control device 800 for cementing operations acquires relevant data from the cementing operation and, based on a preset pressure prediction model, predicts the target pressure curve of the wellhead pressure over time. It then adjusts the parameters of the PID controller according to this target pressure curve to obtain a tuned PID controller. This tuned PID controller then controls the wellhead pressure, ensuring the bottomhole pressure remains within a safe pressure window. This technical solution obtains the target pressure curve of the wellhead pressure over time through a pressure prediction model, allowing for PID controller parameter tuning. The tuned PID controller then controls the wellhead pressure, ensuring the bottomhole pressure remains within a safe pressure window. This solution eliminates the need for manual adjustment to achieve pressure control in cementing operations, effectively replacing manual pressure control, reducing errors caused by manual operation, and achieving automated wellhead pressure control. The PID controller enables closed-loop precise pressure control, improving the success rate of cementing operations, significantly reducing cementing costs, minimizing safety accidents, and achieving the goal of safe and efficient cementing operations.

[0132] In one embodiment, the pressure prediction module 820 is further configured to: determine a first curve of liquid column pressure changing with time and a second curve of circulating friction changing with time based on relevant data, wherein the relevant data includes the vertical height of the liquid column changing with time; and determine a target pressure curve based on the first curve, the second curve, and a preset target bottom hole pressure.

[0133] In one embodiment, the relevant data also includes the fluid density of the liquid column; the pressure prediction module 820 is further configured to: determine the liquid column pressure according to the following formula (1):

[0134]

[0135] Among them, P l ρ is the pressure of the liquid column. i Let g be the fluid density of the i-th segment of the liquid column, g be the acceleration due to gravity, and h be the velocity of the liquid. i Let be the vertical height of the i-th liquid column.

[0136] In one embodiment, the relevant data also includes the friction coefficient of the liquid column, the average flow velocity of the liquid column, the fluid density of the liquid column, and the equivalent diameter of the liquid column; the pressure prediction module 820 is also used to: determine the cyclic friction according to the following formula (2):

[0137]

[0138] Among them, P f For cyclic friction, f i Let ρ be the friction coefficient of the i-th segment of the liquid column. iLet v be the fluid density of the i-th liquid column. i Let D be the average flow velocity of the i-th liquid column. hy h is the equivalent diameter of the liquid column. i Let be the vertical height of the i-th liquid column.

[0139] In one embodiment, the parameter adjustment module 830 is further configured to: adjust the parameters of the PID controller based on the target pressure curve using a trial-and-error method, so as to obtain the PID controller with tuned parameters.

[0140] In one embodiment, the parameter adjustment module 830 is further configured to: adjust the parameters of the PID controller according to the target pressure curve based on the trial-and-error method and the preset PID parameter range, so as to obtain the PID controller after parameter tuning.

[0141] In one embodiment, the relevant data also includes flow rate; the control device 800 for cementing operations is further configured to: adjust the opening of the throttle valve to change the flow rate when the bottom hole pressure is not within the safe pressure window, so as to obtain adjusted relevant data; redetermine the adjusted target pressure curve based on the adjusted relevant data according to the preset pressure prediction model; readjust the parameters of the PID controller according to the adjusted target pressure curve to obtain a PID controller with retuned parameters; and control the wellhead pressure through the PID controller with retuned parameters so that the bottom hole pressure remains within the safe pressure window.

[0142] This invention provides a machine-readable storage medium on which a program or instruction is stored. When the program or instruction is executed by a processor, it implements the control method for cementing operations according to the above embodiments.

[0143] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0144] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0145] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0146] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0147] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0148] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0149] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, 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 technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0150] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0151] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A control method for a cementing job, characterized in that, The control method includes: Obtain relevant data for cementing operations; Based on a preset pressure prediction model, the target pressure curve of wellhead pressure changing with time is predicted according to the relevant data. Adjust the parameters of the PID controller according to the target pressure curve to obtain the PID controller with the parameters tuned. The wellhead pressure is controlled by the PID controller after the parameters are set, so that the bottom hole pressure is kept within the safe pressure window. The step of predicting the target pressure curve of wellhead pressure over time based on the preset pressure prediction model and the relevant data includes: determining a first curve of fluid column pressure changing over time and a second curve of circulating friction changing over time based on the relevant data, wherein the relevant data includes the vertical height of the fluid column changing over time; and determining the target pressure curve based on the first curve, the second curve, and the preset target bottom hole pressure. The relevant data also includes the fluid density of the liquid column; determining the first curve of the liquid column pressure changing with time based on the relevant data includes determining the liquid column pressure according to the following formula (1): Equation (1) wherein, is the liquid column pressure, is the fluid density of the i-th liquid column, is the gravitational acceleration, is the liquid column vertical height of the i-th liquid column; The relevant data also includes the friction coefficient of the liquid column, the average flow velocity of the liquid column, and the equivalent diameter of the liquid column; the determination of the second variation curve of the cyclic friction over time based on the relevant data includes determining the cyclic friction according to the following formula (2): Equation (2) in, The cyclic friction, Let be the coefficient of friction of the i-th segment of the liquid column. Let be the fluid density of the i-th segment of the liquid column. Let be the average flow velocity of the i-th segment of the liquid column. Let be the equivalent diameter of the liquid column. Let be the vertical height of the i-th liquid column. The relevant data also includes flow velocity; the control method further includes: adjusting the opening of the throttle valve to change the flow velocity when the bottom hole pressure is not within the safe pressure window, so as to obtain adjusted relevant data; based on a preset pressure prediction model, redetermining the adjusted target pressure curve according to the adjusted relevant data; readjusting the parameters of the PID controller according to the adjusted target pressure curve to obtain a PID controller with retuned parameters; controlling the wellhead pressure through the PID controller with retuned parameters so that the bottom hole pressure remains within the safe pressure window.

2. The control method according to claim 1, characterized by, The step of adjusting the parameters of the PID controller according to the target pressure curve to obtain the PID controller with tuned parameters includes: Based on the trial-and-error method, the parameters of the PID controller are adjusted according to the target pressure curve to obtain the PID controller with the parameters tuned.

3. The control method according to claim 2, characterized by, The method of adjusting the parameters of the PID controller according to the target pressure curve using a trial-and-error approach to obtain the PID controller with tuned parameters includes: Based on the trial-and-error method and the preset PID parameter range, the parameters of the PID controller are adjusted according to the target pressure curve to obtain the PID controller with the parameters tuned.

4. A processor, comprising: It is configured to perform the control method for cementing operations as described in any one of claims 1 to 3.

5. A control device for a cementing job, characterized in that The control device includes: The data acquisition module is used to acquire relevant data for cementing operations; The pressure prediction module is used to predict the target pressure curve of wellhead pressure changing over time based on the preset pressure prediction model and the relevant data. The parameter adjustment module is used to adjust the parameters of the PID controller according to the target pressure curve to obtain the PID controller after parameter tuning. The pressure control module is used to control the wellhead pressure through the PID controller after the parameters are set, so that the bottom hole pressure is continuously within the safe pressure window; The pressure prediction module is further configured to: determine a first curve of liquid column pressure changing with time and a second curve of circulating friction changing with time based on the relevant data, wherein the relevant data includes the vertical height of the liquid column changing with time; and determine the target pressure curve based on the first curve, the second curve, and a preset target bottom hole pressure. The relevant data also includes the fluid density of the liquid column; the pressure prediction module is further used to determine the pressure of the liquid column according to the following formula (1): Equation (1) wherein, is the liquid column pressure, is the fluid density of the i-th liquid column, is the gravitational acceleration, is the liquid column vertical height of the i-th liquid column; The relevant data also includes the friction coefficient of the liquid column, the average flow velocity of the liquid column, and the equivalent diameter of the liquid column; the pressure prediction module is also used to: determine the cyclic friction according to the following formula (2): Official (2) in, The cyclic friction, Let be the coefficient of friction of the i-th segment of the liquid column. Let be the fluid density of the i-th segment of the liquid column. Let be the average flow velocity of the i-th segment of the liquid column. Let be the equivalent diameter of the liquid column. Let be the vertical height of the i-th liquid column. The relevant data also includes flow velocity; the control device for cementing operations is further configured to: adjust the opening of the throttle valve to change the flow velocity when the bottom hole pressure is not within the safe pressure window, so as to obtain adjusted relevant data; redetermine the adjusted target pressure curve based on the preset pressure prediction model and the adjusted relevant data; readjust the parameters of the PID controller according to the adjusted target pressure curve to obtain a PID controller with retuned parameters; and control the wellhead pressure through the PID controller with retuned parameters so that the bottom hole pressure remains within the safe pressure window.

6. A machine-readable storage medium having stored thereon a program or instmctions, characterized in that, When the program or the instructions are executed by the processor, they implement the control method for cementing operations according to any one of claims 1 to 3.

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