Rotatable Cam Overshot Tool for Variable-Size Well Object Retrieval
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Solution Overview
Problem
Conventional overshot fishing tools are limited in retrieving objects of varying sizes, as they can only handle differences in size up to 0.06 inches, making them ineffective for a wide range of objects stuck in wellbores.
Innovation Solution
An overshot tool design featuring a rotatable cam within a housing, where the cam axis can be aligned and misaligned with the housing axis to grip objects of different sizes, allowing for effective retrieval by sliding over the object and securing it through rotation of the cam relative to the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional overshot fishing tools are used, then the tool structure is simple, but the tool can only retrieve objects with size variation of 0.06 inch or less
Solution Approach 1:
The cam mechanism is rotatable relative to the housing, allowing the cam bore axis to be dynamically adjusted between aligned and misaligned positions. This dynamic adjustment enables the tool to adapt to objects of varying sizes by changing the grip configuration through rotation, thereby resolving the contradiction between adaptability and structural simplicity.
Solution Approach 2:
The tool changes the geometric parameter of the cam bore axis orientation (aligned vs. misaligned) to modify the gripping characteristics. By rotating the cam to different angular positions, the effective internal diameter and grip tightness are adjusted, enabling retrieval of objects across a wider size range without complicating the basic tool structure.
2Reliability
If the cam bore axis is misaligned with the housing bore axis, then the tool grips the object securely, but the object cannot be easily inserted into the tool
Solution Approach 1:
The cam mechanism allows dynamic switching between two operational states: aligned position for easy insertion and misaligned position for secure gripping. The operator can rotate the cam during operation to transition between these states, achieving both easy insertion and reliable grip without compromising either function.
Solution Approach 2:
The cam is initially positioned in the aligned state before operation to facilitate easy insertion of the object. After the object is inserted, the cam is rotated to the misaligned position to establish secure gripping. This preliminary positioning resolves the contradiction by ensuring the tool is in the optimal state for each operational phase.
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
Enables the efficient retrieval of objects from wellbores with varying sizes, improving manufacturing ease compared to prior tools, and providing effective and efficient retrieval methods.
Implementation Method 1
The cam and housing being rotatable relative to each other from an aligned position wherein the cam bore axis and the lower portion axis coincide to a misaligned position wherein the cam bore axis and the lower portion axis are offset and parallel to each other; and the lower portion of the housing bore and the cam bore being open at a lower end of the housing for sliding over an object in the well while the cam bore axis and lower portion axis are in the align position, so that subsequent rotation of the housing and the cam relative to each other causes the cam bore axis and the lower portion axis to move toward the misaligned position, thereby gripping the object for retrieval
Data Source
AI summary
An overshot tool for retrieving an object in a well includes a housing having a housing bore with upper and lower portions. A cam having a cam bore is carried in the upper portion of the bore. The housing and the cam are rotatable relative to each other from an aligned position, in which the cam bore axis and the housing bore lower portion axis coincide, to a misaligned position, in which the cam bore axis and the housing bore lower portion axis are misaligned with each other. The housing bore and the cam bore are open at a lower end for sliding over an object in the well when the tool is in the aligned position. Rotation of the housing and the cam relative to each other causes the cam bore axis and the lower portion axis to move toward the misaligned position, thereby gripping the object for retrieval.