Drill String Clutch Assembly for BHA Drag and Backdriving
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Solution Overview
Problem
Conventional drill strings face issues with undergauge boreholes and drill pipe sticking due to wear, caving, and stuck cuttings, leading to significant stress on expensive components like rotary steerable systems during tripping out and back reaming procedures.
Innovation Solution
A clutch assembly is introduced that includes a releasable clutch mechanism and diverter valve, allowing selective rotation and fluid diversion, reducing drag on the BHA by disengaging the clutch mechanism and diverting fluid to the annulus during tripping or back reaming, thereby protecting sensitive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drill string is pulled out of the borehole during tripping out, then the drill pipe can be retrieved, but significant stress is placed on the BHA including expensive components like rotary steerable systems
Solution Approach 1:
The clutch assembly divides the drill string into two independent rotatable sections: an upper section connected to the surface and a lower section connected to the BHA. The clutch mechanism can disengage these sections, allowing the upper drill string to be pulled out while the lower section and BHA remain stationary, thereby protecting expensive BHA components from stress during tripping operations.
2Ease of operation
If rotation and circulation are reinitiated to free stuck drill pipe, then the BHA can act as a conveyor to move cuttings uphole, but this places additional stress on the BHA components
Solution Approach 1:
The clutch assembly enables independent rotation of the upper drill string section while the lower section remains stationary. During stuck pipe situations, the upper section can be rotated to free the drill pipe without rotating the BHA, eliminating the stress that would otherwise be imposed on expensive BHA components during freeing operations.
3Object-affected harmful factors
If the clutch mechanism is disengaged to reduce drag on the BHA, then stress on components is minimized, but the drill string cannot be rotated as a single unit
Solution Approach 1:
The clutch mechanism dynamically transitions between engaged and disengaged states based on operational requirements. When engaged, the drill string rotates as a single unit for drilling operations. When disengaged, the upper section can be rotated independently or pulled out without rotating the BHA, reducing drag and protecting components during non-drilling operations.
4Object-affected harmful factors
If drilling fluid is diverted to the annulus during tripping, then drag on the BHA is reduced, but fluid circulation through the drill pipe is interrupted
Solution Approach 1:
The diverter valve dynamically switches fluid flow paths based on operational mode. During tripping operations, the valve diverts fluid to the annulus to reduce drag on the BHA. During drilling operations, the valve returns fluid flow to the drill pipe, restoring full circulation for effective cuttings removal and cooling.
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 clutch assembly reduces stress and damage to the BHA by minimizing drag and preventing backdriving, thus protecting expensive components like rotary steerable systems during drill string retrieval.
Implementation Method 1
a one-way bearing assembly allowing rotation of the driveshaft relative to the first assembly portion in a first rotational direction and preventing rotation of the driveshaft in a second rotational direction opposite to the first rotational direction
Implementation Method 2
a releasable clutch mechanism that selectively rotationally locks the first assembly portion with the second assembly portion
Data Source
AI summary
A clutch assembly for use in a wellbore and connectable between a first and second drill string sections is provided. The clutch assembly includes a first assembly portion connectable to the first drill string section and a second assembly portion connectable to the second drill string section. The second assembly portion comprises a driveshaft. The clutch assembly further comprises a releasable clutch mechanism that selectively rotationally locks the first assembly portion with the second assembly portion. The clutch assembly may comprises a one-way bearing assembly allowing rotation of the driveshaft relative to the first assembly portion in a first rotational direction and preventing rotation of the driveshaft in a second rotational direction opposite to the first rotational direction. The clutch assembly may comprise a diverter valve mechanism having an open configuration and a closed configuration.