Steerable Drilling Motor Directional Control
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Solution Overview
Problem
Directional drilling with steerable drilling motors is inefficient due to difficulties in overcoming friction between the drill string and the borehole, leading to time-consuming and costly operations, especially when transitioning between rotary and slide drilling modes, and in maintaining optimal tool face angles.
Innovation Solution
The method involves alternating between two drill string rotation rates to maintain the tool face angle near a desired orientation, using triggers to determine when to change between rotary and slide drilling modes, and employing left hand torque bumps to control the tool face angle without relying on rocking techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If slide drilling mode is used to adjust trajectory, then tool face angle can be controlled, but friction between drill string and borehole makes it difficult to overcome resistance and apply sufficient weight on bit
Solution Approach 1:
The method alternates between rotary drilling mode and slide drilling mode in periodic cycles. During rotary mode, the drill string rotates to reduce friction through rock drilling action. During slide drilling mode, the drill string remains stationary to allow tool face angle adjustments. This periodic switching enables the system to overcome friction limitations while maintaining trajectory control capability.
Solution Approach 2:
The drilling system dynamically transitions between two operational states (rotary and slide modes) based on the drilling requirements. The system monitors parameters such as torque, weight on bit, and tool face angle to determine when to switch modes, creating a adaptive dynamic drilling process that optimizes both friction management and trajectory control.
2Stability of the object's composition
If rotary drilling mode is used to maintain trajectory, then drill string rotation occurs, but transitioning between modes and maintaining optimal tool face angle is time-consuming
Solution Approach 1:
The system performs preliminary actions by establishing stable rotary drilling conditions before transitioning to slide drilling mode for trajectory adjustments. This ensures that the drill string is properly engaged and friction is minimized before switching modes, reducing the time required for mode transitions and maintaining trajectory stability.
Solution Approach 2:
The system uses feedback from drilling parameters (torque, weight on bit, tool face angle measurements) to automatically determine optimal transition timing between rotary and slide modes. This feedback mechanism minimizes unnecessary mode switches and reduces transition time by switching only when truly necessary for trajectory maintenance.
3Productivity
If sufficient weight is applied to overcome friction, then drill bit penetration improves, but torque capacity of the drilling motor is exceeded causing stalling
Solution Approach 1:
The system periodically alternates between rotary drilling mode (where friction is reduced through rotation) and slide drilling mode (where trajectory control is prioritized). This periodic action prevents continuous high torque application that would cause motor stalling, while still achieving adequate penetration rates through the rotary phases.
Solution Approach 2:
The system changes operational parameters by switching between rotary and slide drilling modes, thereby varying the torque requirements. During rotary mode, lower torque is required despite higher weight on bit because rotation reduces friction. During slide mode, trajectory control is maintained with reduced weight application, preventing motor stalling while preserving drilling productivity.
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 enhances the efficiency and accuracy of directional drilling by reducing friction, improving control over tool face angles, and stabilizing drill bit contact, thereby reducing the time and cost associated with reaching target formations.
Implementation Method 1
difficulties in overcoming friction between the drill string and the borehole
Implementation Method 2
The driller attempts to maintain the proper tool face angle by applying torque or drill string angle corrections to the drill string
Data Source
AI summary
Drilling a bore hole comprises rotary drilling at a first rotation rate until a first target value is substantially met, changing the first rotation rate to a second rotation rate when a trigger is substantially met, and then drilling at the second rotation rate until a second target value is substantially met. Preferably, the second rotation rate is substantially zero, so the drilling at the second rotation rate is slide drilling. Finally, the steps of rotary drilling at a first rotation rate, changing the rotation rate to a second rotation rate, and drilling at the second rotation rate are repeated.