Rotary Steerable System Steering Actuation Feedback
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Solution Overview
Problem
Existing rotary steerable systems in downhole drilling operations face challenges in controlling the extension and retraction of hydraulically actuated pads, leading to suboptimal wellbore position control, steering efficiency, and hole quality.
Innovation Solution
A method for drilling a subterranean wellbore that involves rotating a bottom hole assembly with a rotary steerable tool or steerable drill bit, using toolface demands to compute open and close toolface angles for valve actuation, and adjusting these angles based on measured rotation rates and toolface errors to improve steering precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rotary steerable systems use hydraulically actuated pads to steer, then the system can operate in a wide range of drilling operations, but the control of pad extension and retraction is insufficient leading to suboptimal wellbore position control and steering efficiency
Solution Approach 1:
The system implements a feedback control mechanism where actual toolface measurements are continuously compared with demanded toolface values. The controller computes errors and adjusts valve actuation timing and duration to minimize these errors, enabling precise wellbore position control while maintaining system reliability.
Solution Approach 2:
The patent replaces conventional mechanical steering control with an electronically controlled hydraulic system. Digital controllers and electronic valves substitute for traditional mechanical linkages, allowing for more precise and adaptable control of pad extension and retraction timing based on real-time measurements and computed errors.
2Productivity
If the pad extension and retraction timing is not precisely controlled, then the system operation is simple, but steering efficiency and hole quality deteriorate
Solution Approach 1:
The controller computes optimal valve actuation timing in advance based on demanded toolface values and measured rotation rates. The system determines the precise moments when pads should extend and retract before these actions occur, allowing for optimized steering efficiency while accounting for the rotational motion of the drill string.
Solution Approach 2:
The system dynamically adjusts valve actuation parameters based on real-time measurements of rotation rate and actual toolface orientation. The controller continuously updates the timing and duration of pad extension and retraction to maintain optimal steering efficiency as drilling conditions change, rather than using fixed predetermined timing.
3Measurement precision
If toolface measurements are continuously monitored and processed, then directional control precision is improved, but the measurement and control complexity increases
Solution Approach 1:
The system continuously measures actual toolface orientation and feeds these measurements back to the controller. The controller compares measured values with demanded values, computes errors, and adjusts valve actuation accordingly. This closed-loop feedback mechanism improves directional control precision by constantly correcting deviations from the desired wellbore trajectory.
4Manufacturing precision
If the valve actuation is precisely controlled based on rotation rate and toolface angles, then hole quality is improved, but the control system complexity and energy consumption increase
Solution Approach 1:
The system uses periodic valve actuation synchronized with the rotation rate of the drill string. Pads are extended and retracted at specific phases of the rotation cycle based on computed timing, creating a periodic steering action that maintains consistent hole quality. This periodic control approach improves manufacturing precision while managing energy consumption through rhythmic, predictable actuation patterns.
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
The method enhances steering efficiency, achieves better directional control, and improves overall hole quality by precisely controlling the extension and retraction of steering pads during drilling.
Implementation Method 1
hydraulically actuated pads (or blades) to steer
Data Source
AI summary
A method for drilling a subterranean wellbore includes rotating a bottom hole assembly (BHA) in the wellbore to drill. The BHA includes a rotary steerable tool or a steerable drill bit having at least one external pad that extends radially outward into contact with a wall of the wellbore and thereby steers while drilling. A toolface demand is received and processed to compute open and close toolface angles for opening and closing a valve that actuates the steering pad. The rotation rate of the BHA is measured and processed to compute times for opening and closing the valve. The valve is opened and closed at the computed times and toolface angles at which the valve opens and closes are measured. The open and close toolface angles are compared with the measured toolface values to obtain a toolface error which is then processed to compute new open and close toolface angles.