Rotary steering stable inclination mode hole drift angle control method based on recursive control

Abstract

The invention relates to the field of directional drilling, in particular to a rotation steering stable inclination mode hole drift angle control method based on recursive control. According to the method, while drilling data of the current stage are obtained, the deflecting force of the next stage is calculated according to the target hole deviation angle, and the deflecting force is continuously controlled in a recursive mode to achieve stability of the hole deviation angle. The problem of unstable deflecting force is well solved, real-time control over the hole drift angle is achieved, and a new method is provided for real-time control over the hole drift angle of directional drilling in a stable deflection mode.

Description

Technical Field

[0001] This invention relates to the field of directional drilling, and in particular to a method for controlling the inclination angle of a well in a stable inclination mode based on recursive control. Background Technology

[0002] In directional drilling, the drill bit needs to precisely drill along a pre-designed wellbore trajectory to reach the target point underground. The well inclination angle is one of the most critical parameters for controlling the wellbore trajectory. Existing methods mainly rely on the experience of surface engineers or measurement-based feedback control. When the drill string traverses formations of varying hardness, abrasiveness, or anisotropy, its directional drilling capability changes significantly. These methods cannot adapt to these changes in real time, leading to lag or mismatch in control commands and making it difficult to achieve smooth and accurate wellbore trajectory control. Summary of the Invention

[0003] To address the problems of existing technologies, this invention proposes a recursive control-based well inclination angle control method for directional drilling inclination stabilization mode. By real-time reading of drilling data, dynamically calculating the build-up force required to achieve the desired build-up rate, and recursively adjusting it, stable well inclination angle control is achieved, effectively solving the problem of unstable build-up force and providing a precise and real-time control scheme for directional drilling inclination stabilization mode. Through closed-loop feedback control, the invention solves the problems of poor adaptability to formation changes, lag in control response, and low accuracy in directional drilling well inclination angle control methods. The flow of the recursive control-based well inclination angle control method of this invention is as follows: Figure 1 As shown.

[0004] The specific technical solution adopted in this invention includes the following steps:

[0005] Step 1, data reading and initialization, the specific implementation process is as follows:

[0006] Step 1.1, first set the target well inclination angle. The system acquires data from downhole measurement tools in real time during the drilling process, measures acceleration using a triaxial accelerometer, and obtains data on the applied guiding force. And calculate according to formula (1) have to to well inclination angle .

[0007]

[0008] : The axial gravity component measured by a triaxial accelerometer.

[0009] Standard value of gravitational acceleration.

[0010] Step 1.2, set the data reading cycle. The control system uses a preset control cycle. run, It is a fixed time interval. After a period of time, the data is collected again.

[0011] Step 2: Determine the accuracy of the control flow. The specific implementation process is as follows:

[0012] Step 2.1: When the well inclination angle at the end of the current control cycle is equal to the well inclination angle at the end of the previous control cycle, the control method may have a problem or the target well inclination angle has been reached. It is necessary to determine whether the control status is abnormal.

[0013] Step 2.2: The control method continues to run for a separate decision cycle. Within this new control cycle, the control cycle time is extended to determine the current situation and the next step. If the well inclination angle remains unchanged after the decision cycle ends, and the current well inclination angle is not the target well inclination angle, then the control method has a problem, and drilling should be stopped and inspected. If the current well inclination angle equals the target well inclination angle, it proves that the well inclination angle control has achieved the expected results, and control can be terminated. If the well inclination angle changes in subsequent cycles, it proves that the well inclination angle control has not achieved the expected results, and wellbore trajectory control needs to continue.

[0014] Step 2.3: If the well inclination angle changes after extending the control cycle, it proves that the control method is feasible and the well inclination angle control target has not been achieved. The normal control cycle is restored and well trajectory control is continued.

[0015] Step 3: Calculate the tilting force to be applied in the next control cycle. The specific implementation process is as follows:

[0016] Step 3.1, calculate the rate of change of well inclination angle. The specific calculation formula is as follows:

[0017]

[0018] : The well inclination angle at the end of this control cycle.

[0019] : Well inclination angle at the end of the previous control cycle.

[0020] : Drilling distance during this control cycle.

[0021] Step 3.2, calculate the current slope ratio K. The specific calculation formula is as follows:

[0022]

[0023] : Rate of change of well inclination angle.

[0024] : The guiding force applied during the current control cycle.

[0025] Step 3.3: Calculate the tilting force F to be applied in the next control cycle. The specific calculation formula is as follows:

[0026]

[0027] : Proportional control coefficient (unit: kN・m / °), used to adjust the "deviation correction speed", which can be finely adjusted according to the control accuracy and stability requirements: The larger the Kp, the faster the deviation correction, but it may cause the tilting force to jitter; the smaller the Kp, the smoother the correction, the better the stability, but the speed of approaching the target is slower.

[0028] : The slope rate during the current control cycle.

[0029] Step 4, issuing guiding force commands and closed-loop control, the specific implementation process is as follows:

[0030] The calculated steering force command is sent to the drilling tool to guide it in performing the corresponding operation. Steps 1 to 4 are repeated to form a continuous closed-loop recursive control until the well inclination angle reaches the target well inclination angle value.

[0031] Compared with existing technologies, this invention dynamically adjusts the build-up force through a recursive control strategy, effectively avoiding the problem of build-up force fluctuation. It achieves real-time monitoring and dynamic control of the well inclination angle, improving the control accuracy and stability of the directional drilling inclination stabilization mode, and providing reliable technical support for directional drilling operations. Attached Figure Description

[0032] Figure 1 This is the control flowchart of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Step 1: In an embodiment of the present invention, the target well inclination angle is initialized and set. The initial angle is 20°. The target well inclination angle can be adjusted if needed. The control system operates in a continuous control cycle. Internal operation, control cycle The time interval is set to 60 seconds based on the drilling tool performance. A "data acquisition-judgment-calculation-command issuance" process is completed once within each control cycle. After the ∆T time expires, the next round of data acquisition is automatically triggered to ensure control continuity. Data acquisition uses standard downhole measurement tools, and the steering force actuator is a common hydraulic steering system.

[0035] The downhole measurement tools are activated, and data is continuously collected during the drilling process using the measurement-while-drilling system. Acceleration data and axial gravity components are acquired in real time from the triaxial accelerometer. The applied guiding force value Calculate the current well inclination angle according to formula (1). .

[0036] Step 2: At the end of the current control cycle, calculate the current well inclination angle data using formula (1), and denot it as... It also retrieves the well inclination angle data at the end of the previous control cycle and records it as the well inclination angle of the previous cycle. . like and If the absolute value of the difference is ≤0.05°, it is considered that the well inclination angle has not changed, and the control period ∆T is extended by 50%~100%. After running for one temporary control period, the absolute value of the well inclination angle difference is judged again. If the absolute value of the well inclination angle difference is >0.05°, it proves that the control method is effective, and well inclination control continues.

[0037] If the absolute value of the well inclination angle difference is less than 0.05°, it is necessary to determine whether the well inclination angle has reached the target value or whether there is a problem with the control method. If the well inclination angle is not the target well inclination angle, it is determined that there is a fault in the control method (possibly a faulty measuring tool, jammed actuator, or mismatched algorithm parameters). A stop command should be issued immediately to stop drilling operations and investigate equipment and parameter problems. If the well inclination angle is the target well inclination angle, it proves that the well inclination angle control has been successful, and control can be stopped. After proving that the control method is correct and the target well inclination angle has not been reached, the applied guiding force and control cycle time should be restored to the values ​​before the temporary cycle execution, and proceed to the next step.

[0038] Step 3: First, obtain the current control cycle well inclination angle through the calculation using formula (1). Retrieve the well inclination angle at the end of the previous control cycle. and the actual drilling distance within this control cycle. The rate of change of well inclination angle is calculated using formula (2). ,like < , Taking a negative value indicates a decrease in the well inclination angle. > , A positive value indicates an increase in the well inclination angle.

[0039] The ramp rate is then calculated. The actual guiding force applied during this control cycle is retrieved. The current slope rate is calculated using formula (3). This reflects the efficiency of the change in well inclination angle under the current guiding force.

[0040] Based on the obtained well inclination angle change rate, the build-up force F to be applied in the next control cycle of the build-up rate is calculated using formula (4). If the calculation result exceeds the adjustment range of the guiding force of the drilling actuator, the boundary value of the range is taken as the final build-up force.

[0041] Step 4: The control system converts the calculated target build-up force F into standardized control commands and sends them to the drilling actuators via the downhole communication link to guide them in adjusting the steering force output, ensuring that the deviation between the actual applied steering force and the target build-up force F is ≤0.5kN.

[0042] After the command is issued, the control system continues to operate according to the preset control cycle ∆T, repeating steps 1 to 4: re-acquiring downhole data, calculating the well inclination angle, judging the accuracy of the control process, updating the build-up rate and adjusting the build-up force, forming a continuous closed-loop recursive control.

[0043] When a certain control cycle ends, if the absolute value of the difference between the smoothed well inclination angle data and the target well inclination angle is ≤0.1° (meeting the design accuracy requirements), then a guide force holding command is issued to maintain the current build-up force for two control cycles. After confirming that there is no rebound in the well inclination angle, the closed-loop control process is stopped, and the directional drilling stabilization operation is completed. If the target well inclination angle is not reached, the above steps are repeated.

[0044] As can be seen from the above process, the adaptive well inclination angle control method based on real-time formation response identification provided by the present invention can perceive formation changes in real time, effectively overcome the control lag caused by formation changes, and improve the accuracy and reliability of well inclination angle control.

Claims

1. A method for controlling the inclination angle of a build-up mode well trajectory based on recursive control, characterized in that, The method comprises the following steps: Step 1 data reading and initialization: set target inclination angle θ t , real-time acquisition of acceleration data collected by the three-axis accelerometer in the downhole measuring tool, extraction of the axial gravity component g z , calculation of the current inclination angle θ according to formula (1), wherein g0 is the standard value of gravitational acceleration; set the preset fixed control period of the control system as ΔT, and the control system runs in cycles according to ΔT, and downhole data is re-collected every interval ΔT; Step 2 Control flow accuracy judgment: at the end of the current control period, the current period hole inclination and the last control period hole inclination are obtained. The difference between the two is calculated . If |≤0.05°, the control period is extended by 50%-100% to form a judgment period, and the control system operates according to the judgment period and calculates the difference between the hole inclinations again at the end of the judgment period. Step 3: Calculate the build-up force: obtain the drilling distance of the current control period , calculate the rate of change of the inclination angle Δθᵣ according to formula (2) ate , wherein Δθᵣ ate takes a negative value, > Δθᵣ ate takes a positive value, Δθᵣ ate takes 0, call the guiding force F0 applied in the current control period, calculate the current build-up rate K according to formula (3); set the proportional control coefficient , calculate the build-up force F that should be applied in the next control period according to formula (4), if F exceeds the guiding force adjustment range of the drilling execution mechanism, take the boundary value of the adjustment range as the final build-up force; Step 4 Steering force command issuing and closed-loop control: convert the final build-up force into a standardized control command and issue it to the drilling tool, ensure that the deviation between the actual applied steering force and the final build-up force is ≤0.5 kN; repeat steps 1.1 to 1.4 until the end of a control cycle, |≤0.1°, maintain the current build-up force for stable operation for 2 control cycles, and stop the closed-loop control process after confirming that the hole inclination has no rebound.

2. The method of claim 1, wherein, In step 1.2, after the end of the determination period, if the difference of the inclination angle is > 0.05°, the preset fixed control period ΔT is restored and the subsequent steps are continued to be executed; if the difference of the inclination angle is ≤ 0.05° and the current inclination angle ≠ θ t , a stop command is issued to stop the drilling operation and the equipment and parameter problems are checked; if the difference of the inclination angle is ≤ 0.05° and the current inclination angle = θ t , the control flow is directly stopped.

3. The method of claim 1, wherein, In step 1.1, the downhole measurement tool is a measurement-while-drilling system, and the steering force executing mechanism in the drilling tool is a hydraulic steering system.

4. The method of claim 1, wherein, In step 1.3, the proportional control coefficient is fine-tuned according to the inclination angle control accuracy requirement and system stability requirement, the greater the value, the faster the inclination angle deviation correction speed, the smaller the value, the smoother the inclination angle control process.

5. The method of claim 1, wherein, In step 1.1, the preset fixed control period ΔT is determined according to the performance parameters of the drilling tool, and the value range of ΔT is 30s-120s.

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