Moving Riser System for Seabed Hydrate Gas Harvesting
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Solution Overview
Problem
Commercial-scale production of natural gas from seabed hydrates is hindered by technical and environmental issues such as wellbore collapse and high costs associated with drilling and pipeline construction, necessitating a cost-effective and environmentally friendly method for harvesting seabed gas hydrates.
Innovation Solution
A method involving the use of a flexible insulated moving riser to inject hot water with hydrate inhibitors to the seabed, collect dissociated gas using a funnel-shaped device, and transport the gas efficiently back to a ship, eliminating the need for expensive well drilling and pressure reduction, and enabling gas transportation over long distances without pipelines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drilling and pipeline construction methods are used to harvest seabed hydrates, then gas can be extracted and transported, but the costs are extremely high and wellbore collapse occurs
Solution Approach 1:
The invention extracts only the essential function of hydrate dissociation and gas collection, eliminating the need for expensive conventional drilling infrastructure. The floating platform with dissociation chamber separates the gas extraction function from the costly wellbore and pipeline systems, achieving cost-effective gas harvest from seabed hydrates
Solution Approach 2:
The patent introduces a floating platform as an intermediary between the seabed hydrates and land-based infrastructure. This platform serves as a mobile processing station that dissociates hydrates and collects gas without requiring permanent wellbores or pipelines, thereby reducing both cost and environmental impact
2Productivity
If conventional drilling methods are used to access seabed hydrates, then gas can be produced, but wellbore collapse and sand production occur
Solution Approach 1:
The invention removes the problematic wellbore structure from the system entirely. By using a floating platform with a dissociation chamber that processes hydrates directly at the seabed location, the system eliminates wellbore collapse and sand production issues while maintaining continuous gas production capability
Solution Approach 2:
The floating platform provides a dynamic, adaptable solution compared to fixed wellbores. The platform can be positioned optimally and adjusted as needed, avoiding the structural rigidity problems that cause wellbore collapse while maintaining reliable gas production through flexible operational positioning
3Length of moving object
If pipelines are constructed to transport gas from remote seabed deposits, then gas can be transported over long distances, but the construction costs are extremely high
Solution Approach 1:
The floating platform serves as a mobile gas collection and processing unit that can be transported to different locations. This dynamic approach replaces expensive fixed pipeline infrastructure with a relocatable platform that provides the same long-distance transportation capability without the high construction costs of pipeline installation
Solution Approach 2:
The floating platform acts as an intermediary that eliminates the need for direct pipeline connections between seabed deposits and land. The platform collects gas at the seabed location and transports it independently, serving as a self-contained intermediate station that reduces both construction cost and infrastructure complexity
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 allows for economical and efficient harvesting of natural gas from seabed hydrates, reducing environmental impact and operational costs by avoiding wellbore collapse and pipeline construction, while enabling continuous gas production from remote seabed deposits.
Implementation Method 1
a heating device to heat the water to a temperature sufficient to dissociate the gas hydrate
Implementation Method 2
The dissociated gas rises through a riser to a floating platform
Data Source
AI summary
A method and equipment for harvesting natural gas from seabed hydrates are disclosed. The preferred equipment includes a mobile riser, a water injection nozzle, a gas collector, a gas separator, a gas compressor, a water pump, and a water boiler. A fraction of produced gas is used to heat water which is in turn injected to seafloor for dissociating gas hydrates. The preferred method of the invention comprises producing natural gas from seabed hydrates using a production ship with a moving riser installed. This method eliminates the need of drilling wells and thus cuts cost of gas production tremendously.