3D Hydrate Stratum Stability Simulator with Axial Pressure Control
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Solution Overview
Problem
Current experimental equipment is inadequate for simulating stratum stability during natural gas hydrate exploitation, lacking a comprehensive three-dimensional simulation device to assess the mechanical changes and risks associated with hydrate decomposition in sediments.
Innovation Solution
A three-dimensional simulating device comprising a cylindrical model with axial pressure control, environment control, and post-processing units, featuring sensors for monitoring pressure, temperature, and displacement, which simulates hydrate stratum changes and mechanical parameter variations under different conditions, including hydrate decomposition and gas-water release scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional exploitation methods (depressurization, thermal stimulation, chemicals injection) are used to decompose natural gas hydrates, then natural gas can be recovered, but the pore pressure increases and sediments liquefy causing compaction and shear damage to the hydrate stratum
Solution Approach 1:
The patent introduces CO2 as an intermediary substance to replace CH4 in hydrate cavities. The CO2 acts as a mediator that maintains reservoir pressure and prevents sediment liquefaction while enabling methane recovery. The simulation device studies how CO2 injection serves as an intermediate step that protects stratum stability during the exploitation process.
Solution Approach 2:
The patent changes the chemical composition parameter by replacing CH4 with CO2 in the hydrate structure. This parameter change fundamentally alters the exploitation mechanism - CO2 has higher molecular weight and different solubility characteristics that maintain pore pressure and prevent sediment compaction, thereby resolving the contradiction between gas recovery and stratum stability.
2Ease of manufacture
If existing simple experimental equipment is used for hydrate exploitation research, then basic experiments can be conducted, but comprehensive three-dimensional simulation of stratum stability cannot be achieved
Solution Approach 1:
The patent transitions from simple one-dimensional or two-dimensional experimental setups to a comprehensive three-dimensional simulation device. The device incorporates spatial dimensions (radial, axial, and circumferential directions) with multiple sensors distributed throughout the model to capture full three-dimensional stress, strain, and pressure fields during hydrate exploitation simulation.
Solution Approach 2:
The simulation device is segmented into multiple functional modules: a three-dimensional physical model of the hydrate reservoir, axial pressure control unit, environment control unit, and post-processing unit. Each module is further divided into sub-components (sensors, actuators, control systems) that can be independently calibrated and maintained, achieving versatility while managing complexity through modular design.
3Productivity
If hydrates are decomposed by breaking temperature and pressure conditions, then gas production is achieved, but the reservoir stabilization decreases increasing risk for submarine landslide and large-scale collapses
Solution Approach 1:
CO2 serves as an intermediary that maintains reservoir mechanical stability during decomposition. The simulation device investigates how CO2 injection into hydrate-bearing sediments maintains pore pressure and prevents sudden reservoir collapse, thereby enabling sustained gas production while maintaining reliability.
Solution Approach 2:
The simulation device incorporates multiple sensors that provide real-time feedback on pore pressure, effective stress, and sediment deformation during the exploitation process. This feedback mechanism allows dynamic adjustment of exploitation parameters to maintain reservoir stabilization while maximizing gas production, preventing catastrophic failures.
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
Enables comprehensive evaluation of stratum stability and risk assessment in natural gas hydrate exploitation processes, providing high reliability and accuracy through multi-point, three-dimensional monitoring and simulation of various exploitation methods.
Implementation Method 1
Liquid is injected into the axial pressure sealing cavity through the axial pressure injection port, and the liquid pushes the axial pressure sealing piston to apply an axial pressure to the simulating cavity
Implementation Method 2
The natural gas hydrates are solid when being buried in the ocean bed, and are changed from solid to gas when its molecular structure is changed in the exploitation process, that is to say, the hydrates are subjected to phase change in the exploitation process
Data Source
AI summary
A three-dimensional simulating device for the stratum stability in natural gas hydrate exploitation includes a three-dimensional model located in an environmental control unit, an axial pressure control unit, and a post-processing unit. An inner cavity of the three-dimensional model is divided into a sealed simulating cavity and a sealed axial pressure sealing cavity by an axial pressure sealing piston arranged in the inner cavity. A vertical well and a horizontal well stretch into the simulating cavity. The axial pressure control unit, the environmental control unit, and a plurality of sensors in the three-dimensional model are electrically connected to the post-processing unit. This simulating device simulates the external environment and combines in-situ synthesis and decomposition of a hydrate with stratum stability, thereby achieving high reliability and high accuracy, comprehensively evaluating mechanical characteristic change of the stratum and the stratum stability to provide guidance in natural gas hydrate exploitation.