Single Trip Casing Cutting and Pulling Assembly
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Solution Overview
Problem
Current well abandonment techniques require multiple trips into the well, leading to significant time and cost inefficiencies, as they necessitate separate operations for casing cutting and pulling, and the existing solutions face challenges in deep water environments where rotating the drill string to cut the casing can dislodge the seal assembly.
Innovation Solution
A casing cutting and pulling assembly on a drill string that includes a casing spear operated by fluid pressure, a mud motor, and a casing cutter with a valve that limits fluid pressure until the spear is anchored, allowing cutting without rotating the drill string, and additional tools for seal assembly retrieval and packer operation, enabling cutting and pulling on a single trip without surface rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the drill string is rotated from surface to cut the casing, then the casing can be cut effectively, but the seal assembly may detach from the retrieval tool
Solution Approach 1:
The patent replaces the traditional mechanical rotation system with a mud motor that uses fluid flow to rotate the drill string. This substitution allows the seal assembly to remain stationary and securely attached to the retrieval tool while the drill string rotates below it, eliminating the risk of seal assembly detachment during casing cutting operations.
Solution Approach 2:
The mud motor acts as an intermediary mechanism between the stationary seal assembly retrieval tool and the rotating drill string. It enables the transmission of rotational motion to the drill string without requiring rotation of the entire drill string from surface, thus protecting the seal assembly attachment while achieving effective casing cutting.
2Reliability
If multiple trips are made into the well for separate casing cutting and pulling operations, then each operation can be performed carefully, but significant time and costs are incurred
Solution Approach 1:
The patent merges the casing cutting operation and the seal assembly retrieval operation into a single integrated tool assembly that can perform both functions during one trip into the well. The combined tool includes a seal assembly retrieval tool at the top and a mud motor with casing cutting blades at the bottom, enabling simultaneous or sequential completion of both operations without requiring separate trips, thus significantly reducing time and costs while maintaining operational precision.
Solution Approach 2:
The integrated tool assembly is designed with multi-functionality, where the same tool performs both seal assembly retrieval and casing cutting operations. The universal design allows the tool to adapt and complete multiple abandonment tasks in a single trip, improving efficiency while maintaining the reliability needed for each specific operation.
3Reliability
If a valve limits fluid pressure until the spear is anchored, then the casing cutter cannot be activated prematurely, but the system complexity increases
Solution Approach 1:
The valve system is designed to automatically respond to fluid pressure conditions without requiring external control. When fluid pressure reaches a predetermined threshold, the valve automatically opens to activate the casing cutter. This self-regulating mechanism ensures reliable timing of the cutting operation while minimizing the need for complex external control systems, thus balancing reliability with acceptable system complexity.
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 allows for efficient cutting and pulling of casing on a single trip, reducing operational time and costs, and maintains the seal assembly attached during cutting, preventing detachment and ensuring successful operations in deep water environments.
Implementation Method 1
a mud motor operated by fluid flow through the drill string so as to rotate the drill string attached thereto
Implementation Method 2
a casing cutter configured to cut the casing, the casing cutter including a plurality of blades which move from a retracted position to an extended position on fluid pressure in the drill string
Implementation Method 3
the casing spear is operated by fluid pressure in the drill string
Data Source
AI summary
A single trip casing cutting and pulling assembly which includes a casing spear (12), a mud motor (16) and a casing cutter (18), wherein a valve (14) is located between the casing spear (12) and the mud motor (16). The casing spear is operated by fluid flow from surface and the valve (14) prevents operation of the casing cutter (18) until the casing spear (12) is set and casing cutting is required. A method is described for cutting and pulling casing which does not require any rotation of the drill string to operate any part of the casing cutting and pulling assembly. An embodiment is described which includes retrieving the seal assembly (48) on the same trip. Further embodiments describe performing an integrity test and a circulation test on the same trip with the option of making further cuts at shallower depths on the same trip until a section of cut casing can be recovered.