Perforating Gun Solid Propellant Mitigation
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Solution Overview
Problem
During hydrocarbon recovery well perforation operations, excessive dynamic underbalance can cause damage to perforating guns, conveyance tubing, and perforation tunnels due to rapid fluid influx, necessitating a method to manage pressure differentials effectively.
Innovation Solution
Incorporating solid propellant tablets within the perforating gun's free volume, which are ignited to increase pressure and counteract the dynamic underbalance, maintaining the wellbore pressure below hydrostatic levels to prevent excessive fluid influx and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the free volume in the perforating gun is allowed to fill rapidly with wellbore fluids after detonation, then the dynamic underbalance helps clean perforation tunnels of debris, but excessive dynamic underbalance causes damage to the perforating gun, conveyance tubing, packers, and perforation tunnels
Solution Approach 1:
A compressible material is placed in the free volume of the perforating gun before detonation to preemptively counteract the excessive dynamic underbalance. When wellbore fluids rush into the free volume after detonation, the compressible material compresses to absorb the excess fluid, preventing the harmful pressure differential that would otherwise damage equipment and sand the perforation tunnels.
Solution Approach 2:
The compressible material acts as an intermediary between the wellbore fluids and the free volume. It mediates the interaction by absorbing and compressing the excess fluid, thereby reducing the dynamic underbalance to a safe level while still allowing beneficial fluid flow to clean the perforation tunnels.
2Manufacturing precision
If the free volume is permitted to fill with formation fluids, then formation fluids flow through the perforation tunnels toward the free volume cleaning them, but the rapid fluid influx damages the perforating gun, conveyance tubing, and other down-hole equipment
Solution Approach 1:
The compressible material is installed beforehand in the free volume to provide cushioning against the rapid fluid influx. When formation fluids rush into the free volume, the compressible material compresses to cushion the impact, protecting the perforating gun, conveyance tubing, and other equipment from damage while still permitting fluid flow to clean the perforation tunnels.
3Reliability
If the dynamic underbalance is allowed to reach high levels, then debris is effectively removed from perforation tunnels, but sand is carried into the perforation tunnels causing sanding damage
Solution Approach 1:
The compressible material is placed in advance in the free volume to preemptively prevent excessive dynamic underbalance. By compressing the material, the harmful pressure differential is reduced before it can cause sanding, while still maintaining sufficient underbalance to clean debris from the perforation tunnels.
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 use of solid propellant tablets optimizes the wellbore pressure regime, reducing the magnitude and duration of dynamic underbalance, thereby preventing equipment damage and ensuring safe and effective perforation.
Implementation Method 1
igniting a solid propellant within the perforating gun
Implementation Method 2
Upon detonation of the shaped charges within the wellbore, detonation gasses fill the canister and the interior pressure may rise to tens of thousands of psi within microseconds
Data Source
AI summary
A perforating gun assembly for use in a wellbore includes a carrier body and a charge holder disposed within the carrier body. One or more shaped charges are supported by the carrier body and are operably coupled to a detonator for igniting a highly explosive material within the each of the shaped charges. At least one solid propellant tablet is also disposed within the carrier body and is operably coupled to the detonator to ignite and burn immediately after detonation of the shaped charges. The solid propellant tablet burns or is consumed in such a manner to effectively mitigate or control the dynamic underbalance created by the free volume within the carrier body. Burning of the solid propellant tablet may increase the pressure within the carrier body to a level lower than a hydrostatic pressure around the carrier body in the wellbore such that a dynamic underbalance is maintained.