Expandable Subsea Fluid Storage Tank for Thermal Leak Containment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing subsea fluid storage systems face challenges in maintaining fluid temperature above critical thresholds to prevent wax and hydrate formation, managing pressure differentials, and preventing leakage into the marine environment, especially in deep waters where rigid tanks are impractical and thermal insulation is costly.
Innovation Solution
A subsea storage unit with an expandable inner tank enclosed by a flexible peripheral wall, thermally insulated, and surrounded by a floodable gap filled with heated seawater to maintain temperature and pressure balance, featuring multiple barriers to prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If wet thermal insulation is used to maintain oil temperature in subsea pipelines, then the oil temperature can be maintained above critical threshold, but the cost becomes inordinately expensive for long pipelines
Solution Approach 1:
The patent applies preliminary action by heating the seawater in the annular space between the inner and outer tanks before the oil is stored. This pre-heated seawater then serves as a thermal reservoir that passively maintains the oil temperature above the wax appearance point, eliminating the need for continuous active heating or expensive insulation materials on long pipelines.
Solution Approach 2:
The patent uses heated seawater as an intermediary thermal medium between the oil and the cold external environment. The seawater in the annular space acts as a heat transfer medium that absorbs heat from the oil and releases it when the oil temperature drops, thereby maintaining temperature stability without requiring direct insulation of the oil.
2Stress or pressure
If rigid subsea storage tanks are used to withstand hydrostatic pressure in deep water, then pressure containment is achieved, but the tank becomes impractically large and heavy
Solution Approach 1:
The patent employs a flexible bladder or membrane as the inner tank that can deform under hydrostatic pressure. This flexible structure allows the tank to withstand deep water pressures without requiring a rigid, heavy outer shell, significantly reducing the overall weight and size of the storage system while maintaining pressure containment integrity.
Solution Approach 2:
The patent uses a nested structure where the flexible inner tank is placed within a rigid outer tank. The rigid outer tank provides structural support and pressure containment, while the flexible inner tank adapts to pressure changes. This nested arrangement allows the system to withstand hydrostatic pressure without requiring the inner tank to be individually robust and heavy.
3Quantity of substance
If the inner tank volume is increased to store more oil, then storage capacity is improved, but the risk of leakage into the marine environment increases
Solution Approach 1:
The patent uses a flexible bladder or membrane as the inner tank that can deform under hydrostatic pressure. This flexible structure allows the tank to withstand deep water pressures without requiring a rigid, heavy outer shell, significantly reducing the overall weight and size of the storage system while maintaining pressure containment integrity.
Solution Approach 2:
The patent uses a nested structure where the flexible inner tank is placed within a rigid outer tank. The rigid outer tank provides structural support and pressure containment, while the flexible inner tank adapts to pressure changes. This nested arrangement allows the system to withstand hydrostatic pressure without requiring the inner tank to be individually robust and heavy.
4Ease of manufacture
If subsea storage units are deployed in deep water to avoid thermal insulation costs, then insulation cost is reduced, but the temperature difference between contents and surrounding seawater increases
Solution Approach 1:
The patent applies preliminary action by heating the seawater in the annular space between the inner and outer tanks before the oil is stored. This pre-heated seawater then serves as a thermal reservoir that passively maintains the oil temperature above the wax appearance point, eliminating the need for continuous active heating or expensive insulation materials on long pipelines.
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 effectively maintains fluid temperature, prevents wax and hydrate formation, and ensures safe containment with minimal leakage, reducing installation costs and environmental impact.
Implementation Method 1
conduct heat from the fluid through the peripheral wall to heat water in a gap defined between the peripheral wall and a side wall outside the peripheral wall
Implementation Method 2
The side wall is preferably thermally insulated
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A modular subsea fluid storage unit comprises a variable-volume inner tank having a rigid top panel and a peripheral wall that is flexible by virtue of concertina formations. The peripheral wall is extensible and retractable vertically while the horizontal width of the tank remains substantially unchanged. A side wall of a lower housing part surrounds and is spaced horizontally from the peripheral wall of the inner tank to define a floodable gap between the peripheral wall and the side wall that surrounds the tank. An upper housing part extends over and is vertically spaced from the top panel of the inner tank and overlaps the side wall to enclose the inner tank. The floodable gap and the upper housing part enhance thermal insulation and trap any fluids that may leak from the inner tank.