Axial Position-Controlled Toolstring for Well Tubular Cutting
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Solution Overview
Problem
Existing technologies face challenges in performing precise axial position-controlled operations in wells, particularly in cutting loose sections of tubulars below protrusions and retrieving them, due to limitations in depth control and the need for specialized tools.
Innovation Solution
A toolstring comprising a casing cutter tool, a tag sub with collapsible dogs, a pipe spear, and a drill pipe string, which allows for precise cutting and retrieval of tubular components by using the tag sub to land on a protrusion and the casing cutter to cut through slips and locks, enabling the spear to retrieve the cut section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a no-go component with larger OD is used to locate the top of the PBR protrusion, then the positioning accuracy is improved, but the toolstring cannot pass the protrusion and must be pulled out of hole
Solution Approach 1:
The tag sub incorporates collapsible dogs that can change their configuration dynamically. During the run-in operation, the dogs are in an extended state to engage the protrusion for precise positioning. After the cutting operation is complete, the dogs are collapsed to allow the toolstring to pass through the protrusion and be retrieved. This dynamic transformation resolves the contradiction between needing the dogs extended for positioning and needing them collapsed for retrieval.
2Device complexity
If the workstring length is simply tracked from surface, then the measurement process is simplified, but the depth control accuracy deteriorates due to compression, stretch and thermal expansion
Solution Approach 1:
The tag sub with collapsible dogs serves as a self-contained reference marker that is placed directly on the protrusion in the well. This self-service approach eliminates the need for complex surface-based length tracking that must compensate for workstring deformation. The tag sub provides an intrinsic reference point that automatically accounts for all workstring effects, achieving high positioning accuracy without complex measurement systems.
3Measurement precision
If specialized tools are included in the toolstring to locate pup joints or radioactive markers, then the depth control precision is improved, but the toolstring complexity increases and not all operations can include such tools
Solution Approach 1:
The tag sub with collapsible dogs is designed as a universal component that can be used with various protrusions in the well, including PBRs, pup joints, and other reference features. This multi-functional design eliminates the need for specialized locating tools for different types of markers. The same tag sub structure works across multiple applications, providing consistent positioning accuracy without requiring operation-specific tool variations.
Data Source
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AI summary
The invention relates to an axial position-controlled operation toolstring (1) for conducting an axial position-controlled operation in a well. The toolstring (1)comprising from below and up: - a casing cutter tool (20) comprising knives (22); 5 - a tag sub (50) with dogs (52) arranged for landing on a protrusion (90) in said well; - a pipe spear (60); - a drill pipe string (80), wherein said knives (22) of said casing cutter tool (20) are spaced out a predetermined initial distance (L) below the dogs (52) of the tag sub (50); and 0 wherein said dogs (52) are arranged for being collapsible by weight loading against said protrusion (90). The invention also relates to a method wherein said toolstring (1) is used.