Slickline Releasable Overshot

 Slickline Releasable Overshot

Technical Description and Specifications

The Slickline Releasable Overshot is a primary fishing tool engineered for the non-destructive recovery of fish bodies (such as parted slickline tools, shear pin remnants, or small profile equipment) that have an accessible fish neck or cylindrical feature. Unlike a standard overshot, the releasable design allows the operator to engage, jar, and if unsuccessful, disengage and retrieve the fishing string without leaving the overshot downhole.

Key Technical Specifications and Operation

• Function: To engage, securely latch onto, and recover an object (fish) that has a suitable outer diameter (OD) or neck profile, providing a mechanism for controlled release if necessary.

• Design: A multi-component BHA tool that features a bowl (the main body) housing a slip or grapple mechanism, actuated by downward motion over the fish head.

• Engagement Mechanism: Typically uses a collet or slip assembly that locks around the fish OD/fish neck. Downward jarring sets the slips, and subsequent upward jarring is used to retrieve the fish.

• Critical Release Mechanism: The primary differentiator. Release is achieved by a specific action, often involving heavy downward jarring or controlled rotation and downward weight, which retracts the slips and frees the overshot from the fish neck, preserving the fishing string.

• Fish Size Match: The overshot must be precisely matched to the outer diameter of the specific fish neck being recovered. Overshots are sized by the maximum OD they can catch.

• Connection (Customizable):

  • Standard interfaces include proprietary slickline pin threads.

  • Custom order connections are available to ensure compatibility with proprietary quick-connect systems (e.g., HQC, QLS) and non-standard tool string threads.

• Material (Customizable):

  • Standard construction uses high-strength alloy steel (e.g., AISI 4140/4340).

  • Custom material options are available, including NACE MR0175 compliant alloys for the bowl and slips for use in sour service environments ($\text{H}_2\text{S}$).

• Critical Parameters (Customizable Catching OD):

  • Catching Range: The most crucial specification is the range of Outer Diameters (ODs) that the slips can securely engage.

  • Custom Slip Sizes: The overshot bowl can be fitted with custom-machined slips to precisely match non-standard or unusual ODs found on specialized downhole tools. Clients must specify the exact fish neck OD and the desired release mechanism when placing a custom order.