Releasable Mule Shoe Locking Pin for Directional Drilling
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Solution Overview
Problem
In directional drilling of oil and gas wells, the existing universal bottom hole orienting sub assemblies (UBHO subs) are not retrievable if the drill bit becomes stuck, leading to the loss of expensive equipment downhole, including the UBHO sub, directional measurement tools, mud pulser, gamma modules, and batteries, resulting in significant financial loss.
Innovation Solution
A releasable locking pin mechanism is introduced to couple the inner and outer mule shoe assemblies, allowing the directional measurement tool to be withdrawn from the UBHO sub when the drill bit becomes stuck, using a spring-biased detent member, pressure-assisted locking, or a shearable pin configuration to facilitate retrieval of the tool and associated equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed locking mechanism is used to secure the directional measurement tool to the mule shoe, then the tool is reliably held in position during drilling, but the entire assembly cannot be retrieved if the drill bit becomes stuck
Solution Approach 1:
The locking mechanism transitions from a static fixed state to a dynamic releasable state. The locking pin is initially engaged to secure the directional measurement tool during drilling operations, then can be disengaged via a releasing mechanism (such as a wire line operated system or pressure-actuated system) to allow retrieval of the tool assembly if the drill bit becomes stuck, thus resolving the contradiction between reliable locking and retrievability.
Solution Approach 2:
The locking mechanism changes its operational state through parameter changes - either through mechanical displacement of the locking pin, pressure differential changes that actuate the release, or wire line tension changes. These parameter changes enable the transition from a locked state (providing reliability) to an unlocked state (enabling retrievability), resolving the technical contradiction.
2Measurement precision
If the directional measurement tool is permanently locked to the mule shoe, then orientation accuracy is maintained, but equipment loss occurs when the drill bit becomes stuck
Solution Approach 1:
The locking pin provides a dynamic solution that maintains orientation accuracy during normal drilling operations through secure locking, then allows release for equipment retrieval when the drill bit becomes stuck. This dynamic capability resolves the contradiction between maintaining measurement precision and preventing equipment loss.
3Device complexity
If a simple locking mechanism is used, then device complexity is reduced, but the mechanism cannot provide both secure locking and controlled release
Solution Approach 1:
The locking mechanism incorporates self-service features where the same basic structure (locking pin with detent) provides both locking and release functions. The release can be achieved through simple means such as wire line operation or pressure differential, avoiding the need for complex separate locking and unlocking systems, thus resolving the contradiction between simplicity and dual functionality.
Data Source
AI summary
A mule shoe assembly for use in directional drilling which advantageously has releasable locking means to free the directional orienting tool from engagement with the outer mule shoe in situations where the drill bit may become stuck. The releasable locking means comprises a moveable pin which engages an aperture. A first configuration utilizes detent means and spring biasing of the pin. In a second configuration, the pin is adapted for locking engagement by pressurized downhole drilling mud, and may be disengaged from the aperture when pressure from drilling mud ceases. In a preferred embodiment the pin both has detent means and is spring biased, and also relies on drilling mud pressure to remain in locking engagement. The pin may be disengaged upon removal of drilling mud pressure and application of a positive separation force between the directional measurement tool and associated inner tool member, and outer mule shoe member.