Subsea Storage Vessel Flushing System for Well Intervention
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Solution Overview
Problem
Current subsea well intervention systems face challenges in deep-sea environments, including the need for longer, heavier hoses for flushing agents like MEG, potential environmental damage from hydrocarbon release, and the formation of hydrates when mixing hydrocarbons with seawater, which complicates the removal of hydrocarbons from the system without recovering them to the surface.
Innovation Solution
The introduction of subsea storage vessels adjacent to the intervention system allows for the flushing of hydrocarbon fluids into these vessels, minimizing environmental impact and hydrate formation, without requiring surface recovery, using a pump that can be operated by a remotely operated vehicle or surface equipment, and employing a flushing fluid like monoethylene glycol that displaces seawater and hydrocarbons effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If MEG is pumped from a surface vessel to flush hydrocarbons from the intervention system, then hydrocarbons can be removed from the system, but the hose becomes longer and heavier, increasing cost and requiring special handling equipment
Solution Approach 1:
The invention relocates the flushing operation from a surface-based system to a subsea-based system. By positioning storage vessels and pumping equipment at subsea locations adjacent to the intervention system, the flushing operation occurs in a different spatial dimension (from surface to subsea), eliminating the need for long surface hoses and their associated handling requirements
Solution Approach 2:
The invention introduces subsea storage vessels as intermediary components between the intervention system and the ultimate destination of flushed hydrocarbons. These vessels serve as intermediate holding points, allowing hydrocarbons to be flushed from the intervention system into the storage vessels using subsea pumping equipment, thereby avoiding direct surface-based handling
2Productivity
If hydrocarbons are vented out into the sea during flushing, then the intervention system can be cleared, but hydrates may form and cause pollution
Solution Approach 1:
The invention extracts the harmful interaction between hydrocarbons and seawater by providing a dedicated subsea storage vessel that receives flushed hydrocarbons. This separation prevents hydrocarbons from being vented directly into the sea environment, thereby eliminating the conditions that lead to hydrate formation and pollution while maintaining flushing efficiency
Solution Approach 2:
The subsea storage vessel creates a controlled, isolated environment for receiving and holding flushed hydrocarbons. This inert environment prevents the interaction between hydrocarbon gases and seawater that would otherwise lead to hydrate formation, while the vessel's containment structure prevents pollution of the marine environment
3Ease of operation
If the intervention system is opened to allow tooling entry, then operations can be performed, but hydrocarbon escape may damage personnel and equipment
Solution Approach 1:
The invention performs preliminary flushing of hydrocarbons from the intervention system into subsea storage vessels before the system is opened for tooling deployment. This preliminary action removes the hazardous hydrocarbon atmosphere in advance, allowing the system to be safely opened without risk of hydrocarbon escape, while maintaining ease of operation for subsequent tooling deployment
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 solution enables safe exposure of the intervention system to the environment, reduces the need for specialized surface vessels, and minimizes environmental damage by flushing hydrocarbons directly into subsea storage, allowing for efficient tool deployment and operation without significant hydrocarbon release.
Implementation Method 1
a pump for exchanging the flushing fluid provided in the subsea storage vessels and the hydrocarbon fluid provided in the intervention system
Implementation Method 2
MEG is a suitable flushing agent because it does not form hydrates when mixed with hydrocarbon gases and is also denser than seawater. When the MEG is pumped into the lower riser package and lubricator the MEG sinks to the bottom of the lower riser package and push the sea water upwards
Data Source
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AI summary
An apparatus for circulating well fluids in an intervention system is described. The apparatus comprises at least one subsea storage vessel adapted to be located adjacent a subsea intervention system, a first conduit adapted to provide fluid communication between the at least one storage vessel and the intervention system, a second conduit adapted to provide fluid communication between the at least one storage vessel and the intervention system and at least one pump adapted to pump fluid from the at least one storage vessel to the intervention system or from the intervention system to the at least one storage vessel through said first and/or second conduits.