Cyclic Pressure Pulses for Stuck Casing Retrieval
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Solution Overview
Problem
The retrieval of cut casing from boreholes is challenging due to settled solids and corrosion-induced fixation between casing strings, which complicates the removal process and often requires additional tools like the Agitator tool or jar.
Innovation Solution
A tubular retrieval method involving cyclically varying fluid pressure applied to the interior of a cut bore lining tubular section using a pressure pulse-generating device, which helps dislodge solids and facilitate fluid circulation to assist in the retrieval process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional retrieval methods (cutting and mechanical pulling) are used, then casing sections can be removed, but the process becomes complex and time-consuming due to settled solids and corrosion-induced fixation
Solution Approach 1:
The patent replaces complex mechanical retrieval systems (packers, spears, jars, agitation tools) with a fluid pressure-based system. High-pressure fluid is injected through the work string to generate forces that overcome corrosion adhesion and dislodge settled solids, simplifying the retrieval apparatus while maintaining effectiveness.
Solution Approach 2:
The invention utilizes hydraulic principles by circulating high-pressure fluid through the work string and into the annulus between casing strings. The fluid pressure generates lifting and dislodging forces that free the stuck casing section, eliminating the need for mechanical agitation or shock tools.
2Reliability
If additional tools like Agitator or jar are incorporated in the fishing BHA, then retrieval success improves, but the device complexity and operational difficulty increase
Solution Approach 1:
The patent extracts and eliminates the need for complex auxiliary tools (Agitator, jar, multiple packers) by using a straightforward high-pressure fluid injection method. The fluid pressure alone is sufficient to overcome the forces causing casing sticking, thereby improving ease of operation while maintaining reliability.
Solution Approach 2:
The high-pressure fluid system performs multiple functions simultaneously: it dislodges settled solids, overcomes corrosion adhesion, and provides lifting force. This self-service approach eliminates the need for separate agitation and shock tools, simplifying operation while ensuring retrieval success.
3Productivity
If multiple cuts are made in the casing closer to surface, then retrieval may be achieved, but the process time and operational complexity increase
Solution Approach 1:
The high-pressure fluid is injected in advance to dislodge settled solids and break corrosion bonds before mechanical retrieval attempts. This preliminary action prevents the need for multiple sequential cuts and retrieval operations, thereby reducing total time while maintaining 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
The method effectively dislodges settled solids and reduces friction, enabling easier retrieval of cut tubulars by applying pressure pulses to a large area, thus simplifying the process and improving retrieval efficiency.
Implementation Method 1
applying a cyclically varying fluid pressure to the interior of a section of cut bore lining tubular
Implementation Method 2
pressure pulses or varying pressure will tend to push the tubular being retrieved free from the surrounding larger diameter tubular
Data Source
Figure 1
Figure 2
AI summary
A tubular retrieval method comprises applying a cyclically varying fluid pressure to the interior of a section of cut bore-lining tubular. The tubular may be casing which it is desired to remove from a bore. A pulling force may also be applied to the tubular.