Inline Co-Current Phase Separation for Subsea Gas Purification
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Solution Overview
Problem
Existing methods for removing non-targeted components like carbon dioxide and hydrogen sulphide from offshore oil and gas reservoirs are impractical due to large apparatus sizes, high operating pressures, and safety concerns, especially in deep water environments, where conventional counter-current and co-current processes are limited by gas velocity, vessel size, and the need for regular inspections.
Innovation Solution
A method involving a series of inline co-current phase separation and mass transfer steps using high-pressure, low-temperature water as a solvent, which contacts the gas stream to separate non-targeted components, with the option of recycling the solvent and sequestering the components in deep water areas, reducing the need for large pressure vessels and enabling safer, more compact operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional vertical tower scrubbing processes are used for CO2 removal, then removal efficiency is improved, but apparatus size and pumping power requirements increase significantly
Solution Approach 1:
The patent changes the operating parameters from atmospheric pressure to high pressure (matching reservoir conditions), which fundamentally alters the solubility characteristics of CO2 in water. This parameter change enables efficient CO2 removal in a compact apparatus without requiring large volumes of seawater or significant pumping power, as the high pressure environment naturally enhances gas absorption capacity.
Solution Approach 2:
The system utilizes the reservoir's own high pressure environment to drive the CO2 removal process, eliminating the need for external pumping power. The produced water or seawater injected into the reservoir naturally contacts the gas phase under reservoir pressure, allowing CO2 to dissolve and be removed without requiring large external scrubbing apparatus or significant energy input.
2Productivity
If counter-current absorbers are used for gas removal, then mass transfer efficiency is improved, but gas velocity limitations and system complexity increase
Solution Approach 1:
Instead of using counter-current flow as in conventional absorbers, the patent employs co-current flow where both liquid and gas move in the same direction. This inversion of the flow pattern eliminates the flooding and entrainment problems that limit gas velocity in counter-current systems, while still achieving effective mass transfer through the high pressure environment and adequate contact time.
3Reliability
If large pressure vessels are used to accommodate high pressure requirements, then operational safety is improved, but weight, fabrication cost, and footprint increase
Solution Approach 1:
The patent extracts the mass transfer function from large, heavy pressure vessels and implements it within the existing pipeline system. By using inline co-current contactors or simple separation devices within the high pressure flow path, the system achieves the required CO2 removal without requiring separate large-volume pressure vessels, thereby reducing weight, fabrication cost, and footprint while maintaining operational safety through the inherent containment of the pipeline system.
4Productivity
If co-current processes with atomized droplets are used, then mass transfer efficiency is improved, but vessel diameter requirements increase to prevent droplet coalescence
Solution Approach 1:
The patent utilizes the high pressure hydraulic environment to maintain liquid dispersion without requiring large vessel diameters. The high pressure prevents droplet coalescence through increased collision frequency and reduced droplet growth, allowing efficient mass transfer in compact inline configurations rather than requiring large-diameter vessels to accommodate atomized droplet flows.
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 efficient removal and sequestration of greenhouse gases, reducing operational costs and safety risks, as it operates effectively at higher pressures and deeper depths with smaller, lighter equipment, and eliminates the need for solvent regeneration, enhancing the safety and economic viability of offshore gas processing.
Implementation Method 1
water at sea level and atmospheric pressure has a much lower capacity to absorb carbon dioxide than that it does at higher water pressure and lower water temperature
Implementation Method 2
passing the non-targeted component containing gas stream through a mass transfer step
Implementation Method 3
passing the product of step i) through a co-current phase separation step to produce both a non-targeted component containing solvent stream and a partially purified gas stream
Data Source
AI summary
An improved method for the removal of non-targeted components from a non-targeted component containing gas stream, the method includes the steps of: (i) contacting the non-targeted component containing gas stream with a fluid solvent stream; (ii) passing the product of step i) through a co-current phase separation step to produce both a non-targeted component containing solvent stream and a partially purified gas stream; (iii) passing the partially purified gas stream product of step ii) through a mass transfer step to produce a wet gas product; and (iv) passing the wet gas product of step iii) through a final co-current phase separation step to produce a purified gas stream, wherein the method is performed in a subsea location.