Perforating Gun Assembly Pressure Control
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Solution Overview
Problem
Existing well perforation techniques face challenges in creating effective perforation tunnels while maintaining safe pressure conditions, as excessive dynamic underbalance can lead to tunnel failure and safety concerns, particularly in maintaining overbalanced pressure during perforation operations.
Innovation Solution
A downhole tool gun string assembly with a combination of primary and secondary perforating guns, where the secondary pressure generators, such as reactive materials, are used to manage and control the dynamic underbalance by introducing a controlled pressure increase following detonation, counteracting the empty gun chamber effects and optimizing wellbore pressure regimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hollow carrier type perforating guns are used to create dynamic underbalance, then formation fluids flow into the wellbore cleaning the perforation tunnels, but excessive dynamic underbalance causes the perforation tunnel to fail due to sanding
Solution Approach 1:
The patent changes the pressure parameters by introducing a secondary pressure generator that actively modifies the wellbore pressure regime following the initial dynamic underbalance. This secondary pressure source adjusts the pressure differential to prevent excessive underbalance while maintaining the benefits of formation fluid inflow for cleaning perforation tunnels.
Solution Approach 2:
The patent prepares for potential tunnel failure by pre-instilling a secondary pressure generator that will activate after the initial charge detonation. This secondary pressure source acts as a cushioning mechanism to prevent excessive dynamic underbalance before it can cause sanding and tunnel failure.
2Reliability
If overbalanced pressure condition is maintained during perforating, then safety is improved by preventing uncontrolled fluid flow, but formation fluids cannot flow into the wellbore to clean perforation debris
Solution Approach 1:
The patent employs periodic action by first establishing an overbalanced pressure condition for safety, then after charge detonation, allowing a dynamic underbalance period for formation fluid inflow to clean tunnels, and finally activating a secondary pressure generator to restore overbalance. This periodic transition between pressure regimes achieves both safety and cleaning objectives.
Solution Approach 2:
The patent maintains overbalanced pressure as a preliminary condition before perforating to ensure safety. After the perforation event occurs and formation fluids begin flowing, the secondary pressure generator is activated to restore the overbalanced condition, thus preliminarily establishing safety conditions before the harmful debris accumulation can occur.
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 ensures the creation of effective perforation tunnels, enhances safety by managing pressure regimes, and prevents excessive dynamic underbalance, thereby reducing the risk of tunnel failure and improving the integrity of the perforation process.
Implementation Method 1
a secondary pressure generator disposed within or proximate to the carrier gun body that is used to control the pressure regime in the carrier gun body, the surrounding wellbore or both during the perforating event
Implementation Method 2
these perforations are created by detonating a series of shaped charges that are disposed within the casing string
Implementation Method 3
The perforating guns are then connected within a tool string that is lowered into the cased wellbore at the end of a tubing string, wireline, slick line, coil tubing or other conveyance
Implementation Method 4
the secondary pressure generators, such as reactive materials, are used to manage and control the dynamic underbalance by introducing a controlled pressure increase following detonation
Data Source
AI summary
A method comprises providing a gun string assembly within a wellbore and perforating the wellbore using the gun string assembly. The gun string assembly comprises a plurality of perforating guns coupled in series. A first perforating gun of the plurality of perforating guns comprises a first portion of shaped charges, and a second perforating gun of the plurality of perforating guns comprises a second portion of shaped charges operably associated with a secondary pressure generator. The first perforating gun and the second perforating gun are configured in the gun string assembly to provide a pressure transient comprising one or more pressures at a location in the wellbore that meet one or more thresholds.