Pressure Balanced Explosive Pipe Severing Tool
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Solution Overview
Problem
Current pipe severing tools face challenges in effectively cutting through thick drill collars due to high hydrostatic pressures and complex assembly procedures, with reliability compromised by precise timing requirements and vulnerability to stray electric currents.
Innovation Solution
A pipe severing tool with a thin-walled, vented housing that equalizes interior and exterior pressures, allowing for a larger internal diameter for explosive loading, and uses bi-directional boosters and detonation cords to enhance shock value, enabling simultaneous detonation of explosive pellets to increase severing pressure and simplify assembly by allowing transport in pre-assembled components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a significant quantity of high order explosive is used to cut through thick drill collars, then the severing capability is improved, but the explosive energy is attenuated and suppressed by high hydrostatic pressure above 206.94 MPa (30,000 psi)
Solution Approach 1:
The explosive charge is divided into multiple segments (first explosive charge at one end, second explosive charge at the other end) that detonate simultaneously to create opposing shock waves that collide in the center, multiplying the pressure effect to overcome hydrostatic suppression
Solution Approach 2:
The invention uses the hydrostatic pressure environment itself as a counterweight by having shock waves collide to generate pressures that exceed the suppressing hydrostatic pressure, effectively using the environment's pressure against its own suppressive effect
2Stress or pressure
If simultaneous detonation at both ends of the explosive column is implemented to multiply pressure, then the severing pressure is improved, but the timing precision requirement increases
Solution Approach 1:
Detonation cords are pre-installed along the explosive charges during manufacturing, with predetermined lengths that ensure simultaneous arrival at the center collision point, eliminating the need for precise field timing adjustments
Solution Approach 2:
Detonation cords act as intermediaries that transmit the detonation signal with controlled velocity, ensuring synchronized arrival of shock waves at the center regardless of minor variations in explosive pellet dimensions
3Strength
If a thick-walled housing is used to contain the explosive charge, then the structural strength is improved, but the internal diameter for explosive loading is reduced
Solution Approach 1:
The housing uses a thin-walled tubular structure that is sufficiently strong to contain the explosive charge and withstand handling, while maximizing the internal diameter to accommodate the explosive pellets and detonation cords
Solution Approach 2:
The housing is designed as a tubular structure where the length dimension can be extended to provide the necessary explosive charge volume, compensating for the reduced cross-sectional area from thin walls
4Reliability
If complex assembly procedures are used to ensure precise timing, then the detonation synchronization is improved, but the device complexity increases
Solution Approach 1:
The detonation cords are pre-measured and pre-installed during manufacturing with lengths calculated to ensure simultaneous detonation, transferring the precision requirement from field assembly to controlled manufacturing
Solution Approach 2:
The system uses the inherent properties of the detonation cords and explosive velocities to automatically achieve synchronization without requiring complex external timing mechanisms or precise field adjustments
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 solution enhances the reliability and efficiency of pipe severing by maintaining explosive energy despite high hydrostatic pressures and simplifying the assembly process, ensuring effective cutting through thick drill collars while adhering to safety regulations.
Implementation Method 1
a tubular housing having an internal bore and vents, for equalizing fluid pressure within the bore with fluid pressure outside of the housing
Implementation Method 2
uses bi-directional boosters and detonation cords to enhance shock value, enabling simultaneous detonation of explosive pellets to increase severing pressure
Implementation Method 3
severing a drill string above the obstruction... by the remote detonation of an explosive cutting charge
Data Source
Figure 1~3
Figure 4~6
AI summary
A high energy pipe severing tool is arranged to align a plurality of pressure balanced explosive pellets along a unitizing central tube that is selectively separable from a tubular external housing. The explosive pellets are loaded serially in a column and in full view along the entire column as a final charging task. Detonation boosters are pre-positioned and connected to detonation cord for simultaneous detonation at opposite ends of the explosive column. Devoid of high explosive pellets during transport, the assembly may be transported with all boosters and detonation cord connected.