Retrievable Bottom Hole Assembly for Liner Drilling
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Solution Overview
Problem
Current methods for liner drilling in oil and gas wells lack the ability to retrieve and rerun the bottom hole assembly without risking liner buckling, limiting the depth of drilling and preventing the use of directional steering tools and logging instruments.
Innovation Solution
The use of concentric inner and outer strings of tubulars, where the inner string axially and rotationally latches to the outer string, allowing for the inner string to be raised and reassembled without disconnecting from the drill pipe, enabling the retrieval and rerunning of the bottom hole assembly while maintaining torque transfer through the telescoping sub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the drill pipe diameter is reduced to accommodate liner drilling, then the liner installation is enabled, but the bottom hole assembly cannot be retrieved through the drill pipe
Solution Approach 1:
The patent implements a telescoping sub assembly where the inner string (containing the bottom hole assembly) is nested within the outer string (liner). This allows the bottom hole assembly to be retrieved by telescoping the inner string out of the outer string, bypassing the diameter constraint of the drill pipe while maintaining liner drilling capability.
2Adaptability or versatility
If the bottom hole assembly is retrieved during liner drilling, then tool replacement is enabled, but the liner may buckle
Solution Approach 1:
The patent pre-assembles the telescoping sub mechanism before liner drilling begins. The inner and outer strings are connected through the telescoping sub with axial and rotational latching mechanisms already in place. This preliminary configuration allows the bottom hole assembly to be retrieved without disconnecting the liner from the drill pipe, preventing liner buckling while enabling tool replacement.
3Adaptability or versatility
If the inner string is disconnected from the outer string for bottom hole assembly retrieval, then the assembly can be rerun, but torque transfer is lost
Solution Approach 1:
The telescoping sub incorporates dynamic latching mechanisms that allow the inner and outer strings to be connected or disconnected as needed. The axial latch (dogs and grooves) and rotational latch (keys and grooves) can be engaged to maintain torque transfer when the bottom hole assembly is being drilled, and disengaged when retrieval is required, providing flexible force transmission.
Data Source
AI summary
A liner drilling system employs a bottom hole assembly that may be retrieved before reaching the total liner depth. The system includes an outer string made up of a liner and a profile nipple. An inner string including a running tool, drill pipe, and a drill lock tool are lowered into the outer string and rotationally and axially locked to the outer string. Drilling may be performed by rotating the inner string, which also rotates the outer string. The operator may retrieve the inner string by pulling the inner string and the liner upward until the upper end of the liner is located at the drilling rig floor. While supporting the liner at the drilling rig floor, the operator retrieves the inner string, then re-runs it back into the outer string.