Pressure Mitigating Chambers for Annular Pressure Buildup
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Solution Overview
Problem
Temperature-related pressure buildup in the annulus of oil or gas wells remains a significant issue, particularly in subsea and deepwater operations, where existing methods are insufficient to prevent casing collapse or burst, despite various mitigation techniques such as vacuum insulated tubing, compressible fluids, insulating gels, and burst disks.
Innovation Solution
The implementation of systems and methods featuring pressure mitigating chambers integrated with casing strings, containing inert gases and piston assemblies that equilibrate pressure, along with burst disks to manage pressure increases, creating additional volume in the annulus to accommodate thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If compressible fluid (nitrogen) is placed in the trapped annulus to limit pressure buildup, then pressure in the annulus is reduced, but the resulting pressures can still be quite high and may not prevent casing burst or collapse
Solution Approach 1:
The annular space is divided into multiple chambers separated by partition walls, with each chamber containing compressible fluid. This segmentation allows the system to accommodate thermal expansion more effectively while maintaining lower pressures in each individual chamber, thereby protecting casing integrity.
Solution Approach 2:
The compressible fluid (nitrogen) undergoes parameter changes in response to temperature variations. As temperature increases, the nitrogen expands and increases in pressure within the chambers, but the chamber design allows this pressure to be managed and distributed, preventing excessive pressure buildup that could compromise casing integrity.
2Temperature
If vacuum insulated tubing is used to limit heat transfer, then heat transfer from wellbore to trapped annulus is reduced, but this does not fully prevent annular pressure buildup in subsea operations
Solution Approach 1:
The annular space is divided into multiple chambers separated by partition walls, with each chamber containing compressible fluid. This segmentation allows the system to accommodate thermal expansion more effectively while maintaining lower pressures in each individual chamber, thereby protecting casing integrity.
Solution Approach 2:
The compressible fluid (nitrogen) acts as an intermediary substance between the wellbore and the trapped annulus. It absorbs thermal expansion energy and mediates the pressure buildup, preventing direct transmission of thermal stress to the casing while allowing controlled pressure management.
3Temperature
If insulating fluid/gel is placed in the tubing/casing annulus to limit convection heat transfer, then heat transfer is reduced, but annular pressure buildup still occurs and requires additional mitigation measures
Solution Approach 1:
The annular space is divided into multiple chambers separated by partition walls, with each chamber containing compressible fluid. This segmentation allows the system to accommodate thermal expansion more effectively while maintaining lower pressures in each individual chamber, thereby protecting casing integrity.
Solution Approach 2:
The compressible fluid (nitrogen) undergoes parameter changes in response to temperature variations. As temperature increases, the nitrogen expands and increases in pressure within the chambers, but the chamber design allows this pressure to be managed and distributed, preventing excessive pressure buildup that could compromise casing integrity.
4Volume of stationary object
If compressible solid material is strapped to the outer casing string to accommodate fluid expansion, then annular volume is increased, but this approach adds complexity and may not be sufficient for deepwater operations
Solution Approach 1:
The annular space is divided into multiple chambers separated by partition walls, with each chamber containing compressible fluid. This segmentation allows the system to accommodate thermal expansion more effectively while maintaining lower pressures in each individual chamber, thereby protecting casing integrity.
Solution Approach 2:
The system uses compressible fluid (nitrogen) under pressure within sealed chambers to accommodate thermal expansion of trapped annular fluids. The pneumatic/hydraulic pressure of the nitrogen provides a controlled mechanism for volume adjustment without the complexity of external strapping or solid material compression.
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
Effectively mitigates annular pressure buildup by regulating pressure through inert gas expansion and burst disk activation, providing enhanced mechanical integrity for offshore wells, particularly in deepwater environments.
Implementation Method 1
move the piston in such a way as to increase pressure of the inert gas in the chamber and decrease, via expansion, pressure of the annular liquid
Implementation Method 2
annular liquid present in an annular region can, when increased in pressure, access the at least one chamber via an annular pressure buildup port, so as to move the piston
Implementation Method 3
at least one chamber that is integrated with a casing joint on at least one of the casing strings, wherein the at least one chamber contains an inert gas
Data Source
AI summary
The present invention is embodied in systems and methods for mitigating temperature-related pressure buildup in the trapped annulus of an oil or gas well, wherein such systems and methods employ production and/or tieback casing having one or more pressure mitigating chambers, and wherein such chambers make use of pistons, valves, and burst disks to mitigate pressure increases within the annulus.