Multiphase Seepage Simulation for Underground Gas Storage Sealing
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Solution Overview
Problem
There is currently no established theoretical framework or methodology for effectively predicting the sealing integrity of faults, caprocks, wellbores, and reservoirs in underground gas storage facilities in depleted gas reservoirs, which are critical for ensuring the safety and efficiency of injection and withdrawal operations.
Innovation Solution
A physical simulation experiment system is developed, comprising a rock sample sealing, heating, and insulation system, a triaxial stress and confining pressure loading system, an oil-gas-water injection and pore pressure supply system, a vapor-liquid-solid three-phase separation and measurement system, an optical micro/nanofiber gas detection and monitoring system, a distributed fiber optic sensing system, and a gas supply and leakage alarm system, to evaluate the dynamic sealing integrity under alternating loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a physical simulation experiment system is developed to evaluate dynamic sealing integrity, then the ability to predict sealing integrity under alternating loads is improved, but the device complexity increases
Solution Approach 1:
The experiment system is divided into multiple independent functional modules: triaxial stress loading module, fluid injection module, temperature control module, deformation monitoring module, and fracture detection module. Each module can be independently designed, tested, and maintained, reducing overall system complexity while maintaining comprehensive evaluation capability.
Solution Approach 2:
The experiment system is designed to perform multiple functions within a single integrated platform: applying triaxial stresses, injecting multiphase fluids, controlling temperature, monitoring deformation, and detecting fractures. This multi-functionality reduces the need for separate experimental systems and simplifies the overall evaluation process.
2Measurement precision
If comprehensive simulation of multiphase fluid behavior is enabled, then the measurement precision of fluid distribution is improved, but the device complexity increases
Solution Approach 1:
The system uses intermediary measurement techniques such as micro-CT scanning and fiber optic sensors to indirectly observe fluid distribution and rock deformation. These intermediaries provide high-resolution data without requiring direct contact with the multiphase fluid system, thereby maintaining measurement precision while simplifying the injection and measurement apparatus.
Solution Approach 2:
Traditional mechanical measurement methods are replaced with non-invasive techniques such as X-ray micro-CT imaging and optical fiber sensing. These substitutions eliminate complex mechanical contact systems while providing superior measurement precision for fluid distribution and rock deformation.
3Reliability
If the system monitors internal deformation and fracture initiation, then the reliability of sealing integrity evaluation is improved, but the measurement precision requirements increase
Solution Approach 1:
The system pre-installs optical fiber sensors and monitoring devices within the rock sample before applying stresses and injecting fluids. This preliminary action ensures that deformation and fracture data are captured from the earliest stages, improving reliability without requiring ultra-high precision measurement systems, as the sensors are positioned optimally in advance.
Solution Approach 2:
The monitoring system provides continuous real-time feedback on rock deformation and fracture development. This feedback allows for dynamic adjustment of loading and injection parameters, maintaining reliable sealing integrity evaluation while using measurement systems with moderate precision, as the system adapts to the actual rock behavior rather than requiring fixed high-precision thresholds.
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 system addresses the challenge of evaluating dynamic sealing integrity in UGS facilities, enabling comprehensive simulation of multiphase fluid behavior and geological structure stability, thereby guiding scientific site selection and design for improved safety and efficiency.
Implementation Method 1
a heating and insulation unit for heating the rock sample
Implementation Method 2
a triaxial stress loading unit for applying triaxial stress to the rock sample
Implementation Method 3
a confining pressure loading unit for applying a confining pressure to the rock sample
Implementation Method 4
a vapor-phase injection unit and a liquid-phase injection unit to perform oil-gas-water three-phase injection into the rock sample
Implementation Method 5
the distributed fiber optic sensing system is configured to monitor and record internal deformation and fracture initiation of the rock sample during a loading process
Data Source
AI summary
Disclosed is a physical simulation experiment system for vapor-liquid multiphase seepage in an underground gas storage facility in a depleted gas reservoir, including: a rock sample sealing, heating, and insulation system, a triaxial stress and confining pressure loading system, an oil-gas-water injection and pore pressure supply system, a vapor-liquid-solid three-phase separation and measurement system, an optical micro/nanofiber gas detection and monitoring system, a distributed fiber optic sensing system, and a gas supply and leakage alarm system, where the rock sample sealing, heating, and insulation system is used for accommodating and heating a rock sample; and the oil-gas-water injection and pore pressure supply system performs oil-gas-water injection into the rock sample and pore pressure maintenance. The present application aims to overcome the bottleneck problem of evaluating the dynamic sealing integrity of underground gas storage under alternating loads caused by injection and withdrawal.