Drilling System Directional Control via Mode Segmentation
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Solution Overview
Problem
Current drilling methods face challenges in achieving directional control over wellbores using rotary and non-rotary drilling techniques, with rotary steerable drilling devices being expensive and complex, and transitions between drilling modes being time-consuming.
Innovation Solution
A method and system that combine rotary and non-rotary drilling by alternating between rotary, orientation, and directional modes, utilizing a drill string with motors and a processor to control rotation rates and torque, allowing for efficient directional control and minimizing transition delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rotary steerable drilling devices are used for directional control, then drilling rate and borehole smoothness are improved, but device cost and complexity increase
Solution Approach 1:
The drilling operation is segmented into alternating rotary intervals and non-rotary directional intervals. During rotary intervals, the drill string rotates for high-rate drilling. During non-rotary intervals, the drill string is held stationary for directional control using a bent sub or bent motor. This segmentation allows the system to achieve directional control without requiring expensive rotary steerable devices that must provide continuous directional control during rotation.
Solution Approach 2:
The drilling process employs periodic alternation between rotary drilling mode and non-rotary directional drilling mode. The drill string rotates during rotary intervals to maintain high drilling rates, then transitions to non-rotary intervals for directional adjustments. This periodic action pattern allows the system to achieve both high productivity during rotary phases and effective directional control during non-rotary phases, avoiding the need for continuously complex rotary steerable systems.
2Measurement precision
If transitions between rotary and non-rotary drilling modes are made frequently, then directional control precision is improved, but rig time is increased
Solution Approach 1:
The drill string is oriented to the desired toolface direction during the non-rotary directional intervals before transitioning to rotary drilling. By completing the directional orientation adjustment during the non-rotary phase, the system ensures that when rotary drilling begins, the drill string is already positioned correctly, minimizing the need for frequent mid-rotation adjustments and reducing transition time.
Solution Approach 2:
The drilling system dynamically adjusts between rotary and non-rotary modes based on real-time directional control needs. The transition between modes is optimized to balance directional precision requirements with rig time efficiency, allowing frequent mode changes when directional accuracy is critical while minimizing transition duration through efficient procedural sequencing.
Data Source
AI summary
A method of drilling a borehole from a surface location with a drill string, and a system for implementing the method are provided. The method includes a rotary mode that involves rotating the drill string at a rotary mode rotation rate in order to drill the borehole for a rotary interval, an orientation mode that involves rotating the drill string at an orientation mode rotation rate and transitioning the rotation of the drill string from the orientation mode rotation rate to a surface stop orientation, and maintaining the drill string at a surface fixed orientation in order to drill the borehole in a directional mode for a directional interval. The surface stop orientation is selected based upon a predicted relationship between the surface stop orientation and a toolface stop orientation.