Closed Loop Model Predictive Control for Directional Drilling
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Solution Overview
Problem
Automated drilling methods face challenges in maintaining directional control due to feedback measurement delays, leading to spiraling boreholes and reduced hole cleaning efficiency, as sensors are often located far from the drill bit, causing temporal feedback delays and physical constraints in downhole assemblies.
Innovation Solution
A closed-loop model predictive control (MPC) system is implemented to compensate for feedback delays by processing demand and measured attitudes to calculate corrective settings for directional drilling tools, allowing for continuous adjustment of drilling direction and mitigating oscillations, enabling sensors to be placed further up the drill string while maintaining superior directional control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sensors are located a significant distance above the drill bit due to space limitations and physical constraints, then the bottom hole assembly can be properly assembled and operated, but temporal feedback delay occurs leading to drilling attitude oscillations and borehole spiraling
Solution Approach 1:
The system performs preliminary actions by predicting future drilling attitudes based on the dynamic model and current state, then uses these predictions to calculate corrective steering actions in advance. This allows the control system to compensate for the inherent feedback delay by acting on predicted future states rather than relying on delayed past measurements.
Solution Approach 2:
The system implements a closed-loop feedback mechanism where measured drilling attitudes are continuously fed back to the MPC controller. The controller compares measured attitudes with predicted attitudes, calculates errors, and generates corrective steering commands. This feedback loop enables real-time adjustment to eliminate oscillations and maintain precise directional control despite the spatial offset between sensors and drill bit.
2Ease of operation
If feedback measurement delay is present, then sensor placement is simplified and operational constraints are met, but drilling attitude oscillations occur and borehole spiraling increases frictional forces
Solution Approach 1:
The dynamic model predicts future drilling attitudes and required steering actions in advance, allowing the control system to prepare corrective actions before oscillations develop. This preliminary prediction capability enables the system to maintain reliable directional control without requiring sensors to be positioned immediately at the drill bit.
Solution Approach 2:
The closed-loop feedback system continuously monitors measured attitudes, compares them with predicted attitudes from the dynamic model, and generates real-time corrective steering commands. This feedback mechanism eliminates attitude oscillations and prevents borehole spiraling, ensuring reliable directional control even with sensors located above the drill bit.
3Ease of operation
If borehole spiraling occurs due to feedback delay, then frictional forces between drill string and borehole wall increase, but the system continues to operate with simplified sensor placement
Solution Approach 1:
The closed-loop feedback system detects and corrects drilling attitude deviations in real-time by comparing measured attitudes with predicted attitudes and generating corrective steering commands. This prevents borehole spiraling before it can develop, thereby eliminating the increased frictional forces that would result from spiraling, while maintaining the operational flexibility of elevated sensor placement.
Data Source
AI summary
A closed loop method for using model predictive control (MPC) to control direction drilling attitude includes receiving a demand attitude and a measured attitude. The received attitudes are processed using a closed loop MPC scheme to obtain an attitude error that may be further processed to obtain a corrective setting for a directional drilling tool. The corrective setting is then applied to alter the direction of drilling. The process of measuring the attitude, processing via the model predictive control scheme, and applying a corrective setting may be repeated continuously while drilling. The disclosed methodology is intended to provide for superior directional control during closed loop directional drilling operations.