Casing Recovery Through Perforation Washing and Downhole Pulling
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Solution Overview
Problem
Existing methods for removing casing from wells are time-consuming and inefficient due to the need for multiple trips into the well to wash out debris, with limited lengths of casing that can be pulled in a single trip, and lack of well control during cutting processes.
Innovation Solution
A method involving determining a casing cutting target depth, perforating the casing, washing the annulus with fluid through perforations, gripping the casing, and periodically pulling the section if free, using a downhole power tool to exert greater force if necessary, and a bottomhole assembly with a wash tool, spear, and downhole power tool to facilitate this process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple trips into the well are made to wash out debris and remove casing sections, then complete casing removal is achieved, but operation time and cost increase significantly
Solution Approach 1:
The invention combines multiple previously separate operations (washing, cutting, and pulling) into a single integrated tool assembly that performs all functions during one trip into the well. The wash tool, cutting tool, and pulling mechanism are merged into one bottomhole assembly, eliminating the need for multiple trips and significantly reducing operation time while ensuring complete casing removal.
Solution Approach 2:
The washing operation is performed preliminarily before cutting and pulling. By washing out the debris in advance during the same trip, the casing section is prepared for successful pulling without requiring additional trips. This preliminary action ensures that the casing can be removed completely in one operation.
2Ease of operation
If only short sections of casing are washed and pulled per trip, then casing can be removed, but the number of trips and overall time increase
Solution Approach 1:
The tool assembly is designed to be adaptable and dynamic, allowing it to adjust to different casing lengths and debris conditions. The pulling mechanism can handle varying loads, and the washing system can adjust flow rates, enabling the removal of longer casing sections in a single trip rather than being limited to fixed short sections.
Solution Approach 2:
The bottomhole assembly is a universal tool that performs multiple functions (washing, cutting, pulling) that previously required separate specialized tools and trips. This multi-functional design increases productivity by enabling the removal of entire casing sections in one operation rather than requiring multiple trips for different operations.
3Loss of time
If the annulus is not thoroughly washed out before pulling, then operation time is reduced, but the casing may become stuck and cannot be pulled
Solution Approach 1:
The washing action continues throughout the operation rather than being a separate preliminary step. Fluid circulation is maintained continuously during the washing, cutting, and pulling phases, ensuring that debris is constantly removed and the casing remains pullable throughout the entire process, eliminating the risk of the casing becoming stuck.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor washing effectiveness and adjust operations accordingly. By observing fluid return and debris removal patterns, the system can determine when sufficient washing has been achieved, allowing optimization of washing time to ensure pullability without unnecessary delays.
4Ease of operation
If casing is cut into very short pieces to free stuck sections, then casing can be pulled, but the number of operations increases and time and cost increase
Solution Approach 1:
The cutting and pulling functions are merged into a single operational sequence. The cutting tool is integrated with the pulling mechanism, allowing the casing to be cut and pulled in one continuous operation rather than requiring separate cutting and pulling trips. This eliminates redundant operations and increases productivity.
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
Significantly reduces the time required to remove casing by allowing longer sections to be pulled in a single trip, minimizing washing time and enabling efficient debris removal with enhanced pulling force.
Implementation Method 1
passing fluid through the perforations into the annulus to clear at least a portion of the debris
Implementation Method 2
gripping the casing and periodically pulling the section of casing
Implementation Method 3
pulling the section of casing from the well
Data Source
AI summary
Method of removing casing from a well, in which an annulus between the outside of the casing and the inside of a surrounding downhole body is at least partially filled by debris, the perforated section of casing is washed in casing lengths shorter than the perforation length and an attempt made to pull the casing after each shorter length is washed. If the casing is free after washing only a shorter section of the perforated section of casing then it can be recovered and saves the washing time. A bottom hole assembly is described which includes a downhole power tool to exert a greater force to pull the section of casing between washing steps.