Pressure-Actuated Tool Connection Mechanism for Downhole Work Strings
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Solution Overview
Problem
Conventional methods for connecting and disconnecting downhole tools in a work string often fail, leading to the lower end of the string falling into the wellbore, necessitating a secure latching and unlocking mechanism for upper and lower tool assemblies.
Innovation Solution
The method involves positioning a work string adjacent to sealing rams in a BOP assembly, creating differential pressure zones to move a piston element, which causes relative rotational movement of locking elements, allowing for secure locking and unlocking of the tool assemblies through axial or rotational movement, utilizing mating members like teeth and notches or threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional connection methods are used for downhole tools, then the connection process is simple, but the reliability of connection fails and tools may fall into the wellbore
Solution Approach 1:
The patent employs hydraulic pressure differentials to actuate the locking mechanism. Pressure applied to a piston moves the piston axially, which through a follower groove mechanism, rotates the locking element to engage or disengage locking teeth, providing reliable automated connection and disconnection without manual intervention
Solution Approach 2:
The patent replaces manual mechanical manipulation with an automated pressure-actuated system. The locking element rotation, traditionally requiring manual threading or latching, is now achieved through hydraulic pressure differentials acting on a piston that converts linear motion to rotational motion via a groove mechanism
2Ease of operation
If manual manipulation is used for connecting tools, then the device complexity is low, but the ease of operation deteriorates due to failure risks and complex procedures
Solution Approach 1:
The locking mechanism is designed to self-latch and self-unlock through pressure differentials. When pressure is applied to the piston, the system automatically rotates the locking element to engage or disengage, eliminating the need for manual manipulation while maintaining secure connection through the interlocking teeth
Solution Approach 2:
The locking element is designed to be dynamically controllable through pressure actuation. The system transitions between locked and unlocked states based on pressure differential application, allowing flexible and safe operation without manual intervention while maintaining structural integrity through the groove and follower mechanism
3Reliability
If secure latching mechanism is implemented, then the reliability improves, but the device complexity increases with additional locking components
Solution Approach 1:
The patent combines multiple functions into integrated components. The piston serves both as a pressure actuator and as the mechanism that drives locking element rotation. The groove and follower system integrates the conversion of linear piston motion to rotational locking element motion, reducing the need for separate mechanical linkages
Solution Approach 2:
The locking mechanism is segmented into distinct functional elements: the piston for pressure actuation, the groove for motion conversion, the follower for rotational coupling, and the locking teeth for engagement. This segmentation allows each component to perform its specific function efficiently while maintaining overall system reliability
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
This solution ensures reliable connection and disconnection of downhole tools by maintaining a secure latched position during operation and allowing for safe release, preventing the lower end of the string from falling into the wellbore.
Implementation Method 1
The rams, when actuated, seal wellbore pressure below the lower ram and, further, define a first pressure zone between the rams and a second pressure zone above the upper rams. A differential pressure is applied across the pressure zones, moving a piston element in the tool assembly.
Implementation Method 2
The relative axial movement of the locking elements can be responsive to a biasing spring.
Data Source
AI summary
A method is presented for connecting and disconnecting sections of a work string for use in a subterranean wellbore. A preferred method of disconnecting includes the steps of positioning a stinger and a downhole tool assembly of a work string adjacent upper and lower sealing rams, such as in a BOP and lubricator assembly. The sealing rams are closed, defining a first and second pressure zone adjacent the tool. A differential pressure is applied across the pressure zones, moving a piston element in the tool assembly. Axial movement of the piston element causes relative rotational movement of cooperating locking elements. In one embodiment, the locking elements are rotated to an unlocked position and then move relative to one another axially in response to a biasing spring. The relative axial movement of the locking elements results in unlatching of a latching assembly, thereby disconnecting the tool and stinger.