Subsea Spherical Separator for Deepwater Multiphase Fluids
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Solution Overview
Problem
Subsea separation of production fluids into gases and liquids becomes impractical at water depths greater than 1500 meters due to increased external pressure, making traditional large diameter separators impractical and costly to fabricate, and leading to challenges in maintaining efficient oil and gas recovery.
Innovation Solution
A compact subsea multiphase separation system that uses a circular distribution header to separate production fluids into gas and liquid streams, with upper and lower lines feeding into separate headers and a downcomer to manage entrained liquids, allowing for efficient gas-liquid separation while reducing material and weight requirements, enabling the use of single-phase pumps and minimizing hydrate formation and corrosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional large diameter separators are used for subsea separation, then effective gas-liquid separation can be achieved, but the wall thickness increases significantly at depths greater than 1500 meters due to increased external pressure from hydrostatic head
Solution Approach 1:
The separator is divided into multiple segments or sections along its length, allowing each segment to be optimized for local pressure conditions. This segmentation enables the structure to better withstand external pressure without requiring uniformly thick walls throughout the entire vessel, thus reducing overall material usage and weight while maintaining separation effectiveness.
Solution Approach 2:
The patent transitions from traditional horizontal or vertical cylindrical separators to a three-dimensional spherical separator design. This dimensional change allows the separator to utilize radial stress distribution more efficiently, where the spherical geometry naturally withstands external pressure better than cylindrical forms, reducing the required wall thickness at depth while maintaining structural integrity and separation performance.
2Strength
If vessel wall thickness is increased to withstand external pressure at depths greater than 1500 meters, then structural integrity is maintained, but fabrication becomes challenging and project economics are negatively impacted
Solution Approach 1:
The patent changes the geometric parameters of the separator from traditional cylindrical shapes to a spherical configuration. This parameter change fundamentally alters the stress distribution characteristics, allowing the structure to achieve the required structural integrity at depth with more manageable wall thicknesses that are easier to fabricate and assemble, thereby improving ease of manufacture while maintaining strength.
3Stress or pressure
If vessel wall thickness is increased to withstand external pressure, then pressure containment is improved, but the added material and weight impact project economics and vessel availability for maintenance
Solution Approach 1:
By changing the geometric parameters to a spherical design, the patent achieves more efficient pressure containment through radial stress distribution. This allows the vessel to withstand external hydrostatic pressure at depth with optimized wall thickness that minimizes material usage and weight while maintaining adequate pressure containment, thereby improving project economics and reducing maintenance requirements.
4Adaptability or versatility
If traditional separation systems are used at depth, then separation functionality is provided, but the system complexity and cost increase due to the need for thick-walled vessels
Solution Approach 1:
The spherical separator is designed to perform multiple functions within a single integrated structure: gas-liquid separation, pressure containment, and potential integration with other subsea equipment. This multi-functionality reduces the need for separate specialized components, thereby simplifying the overall system complexity while maintaining full separation functionality and adaptability to various operating conditions at depth.
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 enhances subsea well production by achieving bulk removal of aqueous fluids, reducing flow assurance concerns, lowering hydrate risks, and decreasing hydrostatic head, thus increasing reservoir drive and production efficiency while reducing infrastructure and maintenance costs.
Implementation Method 1
a downcomer configured to allow entrained liquids to flow from the gas outlet line to the liquid outlet line
Implementation Method 2
subsea separation at water depths greater 1500 meters becomes especially challenging... this wall thickness has increased to such an extent that typical gravity separation is not practical
Data Source
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AI summary
A system and method for separation of liquids and gases within a multiphase fluid are provided herein. The method includes flowing a multiphase fluid into a circular distribution header of a multiphase separation system and separating the multiphase fluid into gases and liquids within the circular distribution header. The method also includes flowing the gases into a circular gas header that is above a plane of the circular distribution header and flowing the liquids into a circular liquid header that is below the plane of the circular distribution header. The method further includes flowing the gases out of the multiphase separation system via a gas outlet line and flowing the liquids out of the multiphase separation system via a liquid outlet line, wherein entrained liquids within the gas outlet line are flowed to the liquid outlet line via a downcomer.