Gas Hydrate Sediment Stabilization for Offshore Anchor Stability
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Solution Overview
Problem
Deep-sea sediments destabilization leads to issues with anchor placement, borehole stability, and gas hydrate extraction, causing sand production, water intrusion, and slope instability due to dynamic loads and changes in pore pressure, which threaten the integrity of offshore platforms and gas production.
Innovation Solution
A method involving the injection of gas hydrate-forming substances into deep-sea sediments to create gas hydrate sediment composites, which can be formulated to be either solid and low-permeable for static loads or deformable and permeable for dynamic loads, using different fluid phases and conditions to control the mechanical and hydraulic properties of the sediments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If anchors are made large to transfer loads into poorly consolidated sediments, then load transfer capability is improved, but placement and positioning difficulty increases and seabed footprint increases
Solution Approach 1:
The patent changes the mechanical parameters of the sediment by injecting gas hydrate-forming substances that alter the sediment's consolidation state, transforming it from a soft, poorly consolidated state to a stabilized state with improved load-bearing capacity. This allows smaller anchors to achieve sufficient load transfer without requiring large sizes.
Solution Approach 2:
Gas hydrate sediment composites act as an intermediary material between the anchor and the native sediment. These composites provide a transition zone that improves load distribution and transfer, enabling effective anchoring in previously unsuitable soft sediments without requiring oversized anchors.
2Productivity
If gas hydrate is destabilized by pressure drops during extraction, then gas production is improved, but sand production and water intrusion increase
Solution Approach 1:
The patent applies preliminary stabilization treatment by injecting gas hydrate-forming substances into the sediment before gas extraction begins. This creates a stabilized zone around the extraction well that prevents sand production and water intrusion during subsequent pressure drop operations, allowing productive gas extraction without harmful side effects.
3Reliability
If sediments are mechanically stabilized by gas hydrate formation, then borehole stability and foundation integrity are improved, but sediment permeability decreases
Solution Approach 1:
The patent applies local quality modification by creating zones of gas hydrate-stabilized sediment with different properties in different locations. Areas requiring high stability (borehole walls, foundation zones) are heavily stabilized, while areas requiring permeability (production zones) are treated differently or left untreated, optimizing both stability and productivity.
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 stabilizes deep-sea sediments, prevents sand production, minimizes water intrusion, and enhances the structural integrity of boreholes and slopes, allowing for safe operation of offshore platforms and efficient gas hydrate extraction by altering the mechanical and hydraulic properties of the sediments.
Implementation Method 1
injection of gas hydrate-forming substances into deep-sea sediments to create gas hydrate sediment composites
Data Source
AI summary
A method for mechanically stabilizing deep sea sediments, marine raw material deposits and/or submarine slope and/or to a control/conditioning method for the hydraulic properties of deep sea sediments. A gas hydrate-forming substance is injected into marine or submarine sediments, and gas hydrate sediment composites are formed.