Single-Trip Downhole Casing Removal With Integrated Cut-and-Pull
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Solution Overview
Problem
Conventional methods for removing well casings are time-consuming and expensive, often requiring multiple downhole trips and can be ineffective if sections of casing remain immovable.
Innovation Solution
A method and apparatus for removing casing in a single downhole trip using a downhole tool assembly with a cutting device, spear tool, and downhole pull tool that allows for simultaneous cutting and pulling of casing, minimizing damage to cutting tools and enabling efficient removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to remove casing, then the casing can be removed, but multiple downhole trips are required which increases time and cost
Solution Approach 1:
The patent combines multiple functions (cutting, gripping, and pulling) into a single downhole tool assembly that can be deployed in one trip. The tool assembly includes a cutting device, spear tool for gripping, and pull tool integrated together, allowing all operations to be performed sequentially during a single intervention rather than requiring separate trips for each function.
Solution Approach 2:
The downhole tool assembly serves multiple purposes: it cuts the casing, grips the cut casing section, and pulls it to dislodge it from the wellbore. This multi-functional tool eliminates the need for multiple specialized tools and trips, directly addressing the time and productivity issues.
2Productivity
If conventional methods are used to remove casing, then the casing can be removed, but the process becomes expensive due to multiple trips
Solution Approach 1:
By merging cutting, gripping, and pulling functions into one tool assembly deployed in a single trip, the patent reduces operational costs associated with multiple trips, including equipment mobilization, personnel time, and rig time.
3Reliability
If casing is cut at multiple positions, then removal can be achieved, but the process becomes time-consuming
Solution Approach 1:
The tool assembly performs the cutting action as a preliminary step before gripping and pulling. By pre-cutting the casing at the appropriate position during the single trip, the subsequent gripping and pulling operations can proceed without requiring additional trips, thus reducing overall operation duration while maintaining removal reliability.
4Reliability
If a section casing remains immovable after cutting, then removal fails, but conventional methods lack a pulling mechanism
Solution Approach 1:
The patent integrates a pull tool with anchoring capability into the same assembly as the cutting and gripping devices. This allows the tool to anchor itself to the wellbore or remaining casing structure and apply pulling force to dislodge stuck casing sections, thereby improving reliability without requiring a separate intervention tool.
Solution Approach 2:
The downhole tool assembly universally handles both cuttable and immovable casing scenarios by incorporating cutting, gripping, and pulling functions. This multi-functionality ensures reliable removal regardless of casing condition, addressing the reliability issue while the integrated design keeps complexity manageable.
Data Source
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AI summary
Method and apparatus for removing a downhole casing from a well on a single trip. A downhole tool assembly is arranged on a work string having a downhole pull tool, a spear tool, motor unit and cutting device. The downhole pull tool is set inside a first casing string and the spear tool, motor unit and cutting device are located inside a second casing string, located through the first casing string. The downhole pull tool and spear tool can be configures to grip the respective casings during cutting of the second casing string. The cut casing section can then be pulled using the downhole pull tool to dislodge the casing section, whereupon via attachment to the spear tool, the cut casing section can be removed from the well. The assembly can be re-set at shallower depths in the event that the cut casing section cannot be dislodged for removal.