Retrieval Tool Slips for Casing While Drilling BHA Recovery
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Solution Overview
Problem
Casing-while-drilling operations face challenges in retrieving the bottom hole assembly due to high retrieval forces that can lead to cable breakage or damage to the borehole formations, especially when using wireline or reverse circulation methods.
Innovation Solution
A retrievable unit with a drilling tool and slips is mounted to the casing string, allowing differential pressure to facilitate retrieval by preventing downward movement when pressure is inadequate, and utilizing a check valve and less dense fluid to manage upward flow, enabling safe and efficient retrieval of the bottom hole assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireline retrieval method is used, then retrieval capability is achieved, but cable breakage risk increases due to excessive retrieval force
Solution Approach 1:
The patent introduces an intermediary retrieval tool that engages with the bottom hole assembly to facilitate retrieval. This tool acts as a mediator between the cable and the heavy assembly, distributing the retrieval force and preventing direct cable loading that would cause breakage.
Solution Approach 2:
The retrieval system is segmented into multiple components: the retrieval tool, the bottom hole assembly, and the cable. By separating the retrieval function into distinct segments, the system allows the cable to remain lightweight while the retrieval tool handles the heavy assembly, preventing cable overload.
2Ease of operation
If reverse circulation method is used, then retrieval capability is achieved, but formation damage occurs due to excessive pressure
Solution Approach 1:
The retrieval tool serves as an intermediary device that enables retrieval without requiring excessive reverse circulation pressure. By mechanically engaging the bottom hole assembly, the tool facilitates retrieval through controlled means rather than relying on high-pressure fluid circulation that would damage the formation.
Solution Approach 2:
The patent replaces the purely hydraulic reverse circulation system with a mechanical retrieval tool system. This substitution allows retrieval to be achieved through mechanical engagement and controlled lifting rather than through high-pressure fluid circulation that would damage the formation.
3Force
If differential pressure retrieval is used, then retrieval force is generated, but downward movement prevention is needed when pressure is inadequate
Solution Approach 1:
The slips provide a feedback mechanism that monitors the differential pressure conditions and automatically engages to prevent downward movement when pressure becomes inadequate. This feedback system ensures position stability by detecting when the retrieval force is insufficient and activating the slips to hold the tool in place.
Solution Approach 2:
The slips act as an intermediary safety mechanism between the retrieval tool and the casing string. They mediate the interaction by engaging to prevent downward movement when differential pressure is insufficient, ensuring the tool maintains its position without requiring continuous adequate pressure.
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 solution allows for safe retrieval of the bottom hole assembly without damaging the borehole formations, reducing the risk of cable breakage and maintaining formation stability by controlling pressure and using slips to grip the casing string, thereby overcoming the limitations of existing retrieval methods.
Implementation Method 1
The retrievable unit has a check valve that allows downward flow through the flow passage when supported by the slips at the intermediate point but prevents upward flow
Implementation Method 2
A set of slips on the retrievable unit is adapted to grip the casing string at an intermediate point along the casing string to prevent downward movement of the retrievable unit
Implementation Method 3
The retrievable unit has a check valve that allows downward flow through the flow passage when supported by the slips at the intermediate point but prevents upward flow
Data Source
AI summary
A casing-while-drilling bottom hole assembly is releasably connected with a casing string. A retrieval tool is run into the casing string and latched to the bottom hole assembly. Slips are mounted to the retrieval tool, the slips being retracted during running in. Differential pressure moves the retrieval tool and bottom hole assembly upward, and the slips engage the casing string to prevent downward movement if the pressure differential drops too low. A flow passage extends through the retrieval tool and the bottom hole assembly. A check valve in the retrieval tool allows downward flow through the flow passage but prevents upward flow, so that fluid may be circulated through the retrieval tool and bottom hole assembly while suspended with the slips.