Latchable Reaming Bit BHA Removal Through Liner
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Solution Overview
Problem
Existing drilling techniques face challenges when dealing with troublesome zones, particularly when reamer bits malfunction and fail to retract, requiring extensive time and cost to remove the bottom hole assembly (BHA) through a liner, and previous designs with splined surfaces are prone to bearing failure, necessitating frequent liner removal.
Innovation Solution
A drilling assembly with a latch mechanism that temporarily secures the reamer bit to the liner during BHA removal and reinsertion, allowing reliable engagement and disengagement, and utilizing splines and a shoulder for torque transmission, while the latch mechanism can provide additional support during drilling and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If extendable arm reamers are used to allow BHA removal through liner, then ease of operation is improved, but reliability deteriorates due to arm malfunction preventing BHA removal
Solution Approach 1:
The problematic extendable arm mechanism is completely removed from the reamer design. Instead, the reamer is supported directly by the liner bottom through a bearing, eliminating the arms that could malfunction and refuse to retract, thus resolving the reliability issue while maintaining ease of operation for BHA removal.
Solution Approach 2:
A bearing is introduced as an intermediary component between the reamer and the liner bottom to support the reamer weight. This bearing allows reliable torque transmission through splines while providing a stable support mechanism that doesn't suffer from the malfunctions of extendable arms.
2Ease of operation
If bearing support is used to carry reamer weight on liner bottom, then ease of operation is improved for bit change, but reliability deteriorates due to bearing failure before hole completion
Solution Approach 1:
The latch mechanism is engaged in advance during drilling operations to temporarily secure the reamer to the BHA. This preliminary action ensures that when BHA removal is needed, the reamer is already prepared for transfer to liner support, enabling reliable and quick bit changes without bearing failure issues.
Solution Approach 2:
The system transitions dynamically between two states: during drilling, the reamer is latched to the BHA for stable torque transmission; during BHA removal, the latch releases and the reamer transfers to liner bottom support. This dynamic switching allows the system to optimize for each operational phase without compromising reliability.
3Ease of operation
If reamer bit is fixed near liner bottom with bearing support, then ease of operation is improved for liner support, but adaptability deteriorates by preventing reaming proximate to pilot bit
Solution Approach 1:
The latch mechanism enables dynamic positioning of the reamer. During drilling, the reamer can be positioned anywhere along the BHA by controlling the latch engagement, allowing reaming proximate to the pilot bit when needed. When liner support is required, the latch releases and the reamer naturally settles at the liner bottom, providing both adaptability and operational ease.
4Reliability
If latch mechanism is used to secure reamer to BHA, then reliability is improved for torque transmission, but device complexity increases
Solution Approach 1:
The latch mechanism is designed to be self-actuating through the drilling dynamics. As the BHA is lowered and the pilot bit approaches the liner bottom, the natural movement and weight distribution automatically engage or disengage the latch without requiring external control systems, maintaining reliability while minimizing complexity.
Data Source
AI summary
A drilling assembly supports a liner for making a wellbore. The BHA comprises a pilot bit and a reamer above it that is larger in diameter than the suspended liner. If the BHA needs to be pulled out, the reamer is brought into contact with the liner and a latch mechanism between the two engages as another latch that had held the reamer bit to the BHA is released. The reamer bit stays with the liner as the BHA is pulled and later reinserted. On the way in the BHA latches to the reamer bit which then unlatches from the liner bottom. Preferably, splines and a shoulder on the BHA are used to drive the reamer bit as opposed to any power being transmitted through the latch between the BHA and the reamer bit. However, the latch mechanism between the BHA and the reamer bit could also provide torque and weight on bit for drilling operations. The process may be repeated.