Methane Hydrate Dissociation System Using Geothermal Heating
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Solution Overview
Problem
Current methods for extracting methane hydrate, such as the depressurization and hot water injection methods, face challenges including low productivity, high development costs, risks of subsidence, gas leakage, and inefficient heat supply, leading to economic and technical difficulties in commercialization.
Innovation Solution
A methane hydrate dissociation and gas derivation system that combines geothermal energy by drilling heating and return wells to supply heat to the methane hydrate layer, reducing the need for intense depressurization and fuel consumption, while using geothermal energy to stabilize production and improve recovery ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the depressurization method is used to extract methane hydrate, then fuel consumption is reduced and drilling cost is lowered, but productivity is low and heat supply speed is insufficient
Solution Approach 1:
The patent combines the depressurization method with geothermal heating by integrating a heating well system into the production well structure. The heating unit supplies heat to the methane hydrate layer while the production well maintains reduced pressure, creating a combined method that overcomes the insufficient heat supply of pure depressurization while maintaining its low fuel consumption advantage.
Solution Approach 2:
The production well is designed to serve multiple functions: it acts as both a depressurization well and a heating well. The heating unit within the production well can supply heat to the methane hydrate layer, while the well simultaneously maintains reduced pressure conditions, making the system multi-functional and eliminating the need for separate heating and production wells.
2Productivity
If intense depressurization is applied to accelerate production, then productivity increases, but risks of subsidence, cracking, and gas leakage increase
Solution Approach 1:
The patent changes the thermal parameter by introducing geothermal heating to the system. By supplying heat to the methane hydrate layer, the dissociation process is accelerated thermally, allowing productivity to increase without relying solely on intense depressurization. This parameter change (adding heat) provides an alternative pathway to accelerate production while maintaining seabed stability.
3Temperature
If hot water injection method is used to supply heat to methane hydrate layer, then heat supply is improved, but fuel consumption increases and development investment is large
Solution Approach 1:
The patent utilizes geothermal energy from the earth's natural heat sources to provide the required thermal energy for methane hydrate dissociation. The heating unit taps into geothermal resources, allowing the system to heat the methane hydrate layer without consuming external fuel. This self-service approach uses the earth's own heat to drive the extraction process, eliminating the high fuel consumption associated with conventional hot water injection methods.
4Device complexity
If simple depressurization method is used, then equipment complexity is reduced, but recovery ratio is difficult to improve and production behavior curve is undesirable
Solution Approach 1:
The patent nests the heating unit within the production well structure. The heating unit is integrated into the existing production well, creating a nested configuration where the heating functionality is contained within the production well. This nested design adds heating capability without significantly increasing overall system complexity, as the heating unit shares the wellbore and operational infrastructure with the production well.
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 reduces development costs, enhances productivity, minimizes risks of re-hydration and freezing, and improves the recovery ratio, leading to a more economical and stable methane hydrate extraction process.
Implementation Method 1
supply heat to the methane hydrate layer
Implementation Method 2
pumping up a heat medium from a deep aquifer... supply the heat medium to a methane hydrate layer
Implementation Method 3
methane hydrate to be in a dissociation zone, and deriving dissociated methane gas
Implementation Method 4
reducing the pressure of a methane hydrate layer... deriving dissociated methane gas
Data Source
AI summary
Warm water is pumped up by a pump from an underground aquifer present 1000 to 1500 m below the seabed, geothermal energy is caused to flow through a permeable layer below a methane hydrate layer, a dissociation boundary surface of an un-dissociated area of the methane hydrate layer is dissociated to generate methane gas, the methane gas is led into a production well from peripheral areas and through a gas inlet screen and caused to rise so that the methane gas is collected on the sea.