RSS Tool Face Angle Control via AC Machine Duty Cycle
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Rotary Steerable Systems (RSS) face challenges in precisely controlling the tool face angle during directional drilling operations due to non-linearity and asymmetry caused by factors like friction and stick-slip, which affect the drilling trajectory's accuracy and efficiency.
Innovation Solution
The use of digital pulses to control the torque produced by an Alternating-Current machine, allowing for 'bang-bang control' to accommodate these issues and improve the control of the tool face angle, thereby enhancing the precision and smoothness of the drill string movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional control methods are used for tool face angle in RSS, then the system structure remains simple, but the control precision and trajectory accuracy deteriorate due to non-linearity and asymmetry from friction and stick-slip
Solution Approach 1:
The patent applies parameter changes by modifying the control input parameters (voltage, frequency, duty cycle) of the AC machine to compensate for non-linearities and asymmetries in the tool face angle response. By dynamically adjusting these parameters based on feedback, the system achieves improved trajectory accuracy without requiring complex mechanical modifications to the RSS structure.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the actual tool face angle and comparing it with the desired angle, then using this information to adjust the AC machine control parameters. This closed-loop feedback mechanism compensates for friction and stick-slip effects, improving control precision while maintaining a relatively simple system architecture.
2Measurement precision
If digital pulses with bang-bang control are used to control AC machine torque, then the tool face angle control precision improves, but the control system complexity increases
Solution Approach 1:
The patent employs periodic digital pulse signals with varying duty cycles to control the AC machine torque. This periodic action allows for precise control of the tool face angle by adjusting the pulse width and frequency, achieving high control precision while using a relatively simple digital control implementation compared to continuous analog control systems.
Solution Approach 2:
The patent applies dynamics by making the control parameters (pulse width, frequency, duty cycle) time-varying and adaptive. The control system dynamically adjusts these parameters in real-time based on the current operating conditions and desired tool face angle, enabling precise control while maintaining system flexibility and responsiveness.
3Productivity
If the external body of RSS rotates during drilling operations, then the drilling speed increases, but maintaining the desired tool face angle position becomes more difficult due to rotational dynamics
Solution Approach 1:
The patent uses feedback control to continuously monitor the tool face angle position during rotation and adjust the AC machine control parameters accordingly. This real-time feedback compensates for the effects of rotational dynamics, allowing the system to maintain accurate tool face angle positioning even at high drilling speeds when the external body is rotating.
Solution Approach 2:
The patent applies dynamics by making the control system adaptive to rotational conditions. The control parameters are dynamically adjusted based on the rotation speed and direction, allowing the system to maintain precise tool face angle control throughout the drilling operation regardless of the external body's rotational state.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables more precise and efficient control of the drilling trajectory, leading to faster, smoother, and more accurate wellbore paths, maximizing the value of the drilled well by addressing the limitations of existing RSS systems.
Implementation Method 1
The AC machine may be used to produce the mechanical torque required to adjust the tool face angle of the RSS
Data Source
AI summary
A method for controlling the tool face angle of a rotary steerable system inside a well. The tool face angle is mainly controlled through the determination of the duty cycle of an AC Machine, producing its torque. The controlling duty cycle of the AC Machine is determined through the summing of a duty cycle set point with one or more duty cycle corrective values, using a Pulse Width Modulation technique. The duty cycle corrective values use different cut-off frequencies and update frequencies to accommodate the non-linearity and asymmetry of the system response. The method can also be used for controlling the angular rate of the rotary steerable system.