Downhole Pipe Severing Tool Extraction Method
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Solution Overview
Problem
Existing methods for recovering stuck drill pipes in highly deviated or horizontal wells often damage both the tubular structure and downhole equipment due to the destructive nature of pipe severing tools, leading to costly downtime and equipment damage.
Innovation Solution
A method involving a downhole tool with a pipe severing unit that is lowered to the stuck pipe, then partially withdrawn and triggered remotely to sever the pipe at a safe distance from the downhole tool string, minimizing damage to equipment and allowing for the use of higher explosive or chemical quantities for effective cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional pipe severing tools are used to cut stuck drill pipe, then the pipe can be severed and recovery operations can proceed, but the downhole equipment and tubular structure are damaged by the destructive cutting process
Solution Approach 1:
The pipe severing tool is released and extracted from the downhole tool string before activation. This separates the harmful cutting function from the protected equipment, allowing the tool to be positioned at the cut location, activated remotely, and then discarded while the main tool string remains intact and recoverable.
Solution Approach 2:
The system is divided into two functional segments: the protected downhole tool string that performs positioning and activation, and the disposable pipe severing tool that performs the destructive cutting function. This segmentation allows the harmful function to be isolated from the valuable equipment.
2Strength
If higher quantities of explosive or chemical charges are used to ensure effective pipe cutting, then the cutting capability is improved, but the risk of damage to downhole equipment increases
Solution Approach 1:
The pipe severing tool with high-power charges is extracted from the protected tool string before activation. This allows the use of maximum cutting power without exposing the expensive downhole equipment to the harmful effects of high-energy explosions or chemical reactions.
Solution Approach 2:
The pipe severing tool is designed as a disposable component that is sacrificed during the cutting operation. By using a low-cost, single-use tool, the system can employ high-power cutting charges without risking damage to valuable, reusable downhole equipment.
3Productivity
If the pipe severing tool is activated while attached to the downhole tool string, then the cutting operation can be performed, but the shock waves and debris from cutting damage both the tubular structure and the downhole equipment
Solution Approach 1:
The pipe severing tool is released and positioned at the desired cut location before activation. This preliminary positioning ensures the tool is isolated from the protected equipment, allowing the subsequent cutting operation to proceed without risking damage to the downhole tool string.
Solution Approach 2:
The severing tool is extracted from the tool string connection before the harmful cutting action occurs. This extraction removes the vulnerable equipment from the zone of harmful effects, allowing the cutting operation to be performed with full power without compromising equipment integrity.
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 approach protects downhole equipment by separating it from the severing tool before activation, enabling safer and more effective pipe severing operations in challenging well conditions without damaging the equipment, thus reducing downtime and maintenance costs.
Implementation Method 1
The DCST contains an explosive charge at either end of the tool; both charges are detonated simultaneously. The explosive shock waves meet in the centre of the tool and combine to produce a very high-energy wave capable of cutting through the thickest of pipe.
Implementation Method 2
Chemical cutters use a propellant to generate pressure forcing the chemical, usually Bromine Trifluoride, through a catalyst. The resulting chemical reaction is expelled through the severing head of the cutter at a high temperature and pressure, which cuts the wall of the tubing.
Implementation Method 3
Radial cutting torches use a mixture of powdered metals contained inside the torch body, those metals burn at a very high temperature on ignition by a gas generator. The resultant molten plasma is then ejected through a radial graphic ceramic nozzle and onto the target tubing.
Data Source
AI summary
This invention relates to a method for recovering a tubular structure (3) from a well (1), wherein a so-called free point is defined as the location where the tubular structure is stuck in the well. The method comprising providing a downhole tool string comprising a pipe-severing tool and an upper part of the downhole tool string; lowering the downhole tool string into the tubular structure to release the free pipe. Before the step of triggering the pipe-severing tool to sever the tubular structure, the method includes releasing the pipe-severing tool and subsequent withdrawing the upper part, of the downhole tool string away from the free point towards the surface over at least a predefined distance. The invention relates to a downhole tool string for use in such method.