Gravity-Based LNG Storage and Offloading for Lower-Cost Transfer
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Solution Overview
Problem
The cost of LNG storage and offloading facilities has increased significantly, and existing designs focus mainly on storage tank size optimization and berth utilization, necessitating the exploration of alternative designs to reduce costs and improve efficiency.
Innovation Solution
An integrated storage/offloading facility positioned on a gravity-based structure at a selected seabed location, featuring a liquefaction facility, cryogenic storage tanks, and an LNG transfer facility, with a cryogenic pipeline connecting onshore and offshore tanks, and including a boil-off gas reliquefaction system to minimize boil-off gas loss and utilize it as fuel, allowing for flexible and efficient LNG transfer to LNG carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional onshore LNG storage and offloading facilities are used with insulated pipes on elevated trestles, then LNG transfer can be achieved, but the cost of facilities increases significantly and berth utilization is limited
Solution Approach 1:
The patent moves the storage facility from onshore to offshore by placing it on a gravity-based structure (GBS) in water depths of 50-200 meters. This dimensional shift allows the facility to be positioned closer to the jetty, enabling direct coupling between the GBS and LNG carrier, thereby improving berth utilization while potentially reducing overall facility costs through optimized transfer distances and eliminated onshore infrastructure.
Solution Approach 2:
The offshore storage facility on the GBS serves multiple functions: it acts as both a storage tank and a transfer station, eliminating the need for separate onshore storage and transfer infrastructure. The GBS itself provides structural support, housing, and ballast control, consolidating multiple functions into a single integrated platform that improves both cost efficiency and operational flexibility.
2Ease of manufacture
If storage tank size is increased to leverage economies of scale, then cost per unit may be reduced, but flexibility and adaptability of the facility decreases
Solution Approach 1:
The patent divides the LNG storage system into modular components: the GBS can accommodate multiple storage tanks of varying sizes, and the facility can be configured with different numbers and capacities of tanks depending on specific project requirements. This segmentation allows optimization of cost per unit through scale while maintaining flexibility to adapt to different market conditions and carrier sizes.
Solution Approach 2:
The facility design allows dynamic adjustment of operational parameters including the number of active storage tanks, transfer rates, and ballast water levels. The GBS can be reconfigured for different carrier types and sizes, and storage capacity can be adjusted based on market demand, thereby maintaining flexibility even with large overall capacity.
3Stability of the object's composition
If a gravity-based structure is used for offshore storage, then stability and relocation capability are enhanced, but device complexity increases
Solution Approach 1:
The GBS uses ballast water in ballast tanks to achieve and maintain stability. By controlling the distribution and amount of ballast water, the structure achieves proper trim and stability characteristics while remaining capable of controlled relocation. The ballast system acts as a dynamic counterweight mechanism that simplifies the overall structural design compared to fixed foundations.
4Temperature
If cryogenic pipelines are laid on elevated trestles, then insulation is maintained, but environmental loads on LNG carriers increase and space is consumed
Solution Approach 1:
The patent transitions the pipeline route from onshore elevated trestles to an offshore route connecting the GBS directly to the LNG carrier. This eliminates the need for long onshore trestle structures, reducing environmental loads on carriers and freeing up jetty space while maintaining cryogenic insulation through optimized subsea or short-span above-water piping with appropriate insulation and heat trace systems.
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 design reduces the overall cost of LNG projects by optimizing storage and offloading processes, enhancing stability and flexibility through modular construction and relocation, and minimizing environmental loads on LNG carriers, while maintaining efficient LNG transfer and storage operations.
Implementation Method 1
an integrated storage/offloading facility arranged on a gravity-based structure having a base that rests on the seabed
Implementation Method 2
a first cryogenic storage tank operatively associated with the liquefaction facility for receiving and storing the product stream of LNG
Implementation Method 3
LNG is typically stored in cryogenic storage tanks at the LNG production plant either at or slightly above atmospheric pressure at a temperature of around −160 degrees Celsius
Implementation Method 4
including a boil-off gas reliquefaction system to minimize boil-off gas loss and utilize it as fuel
Data Source
AI summary
An LNG production plant positioned at a production location adjacent to a body of water is described. The LNG production plant includes a plurality of spaced-apart facilities including a first facility and a second facility, each facility provided with plant equipment related to a pre-determined function associated with the production of LNG, where the first facility is an onshore facility and the second facility is an integrated storage/offloading facility arranged on a gravity-based structure having a base that rests on the seabed at a selected location within the body of water.