Subsea Multiphase Separator Vertical Segmentation
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Solution Overview
Problem
Subsea separation of production fluids into gases and liquids becomes impractical at depths greater than 1500 meters due to increased pressure and material requirements, making traditional large diameter separators unsuitable for deepwater environments.
Innovation Solution
A compact subsea multiphase separation system that includes an inlet line with divisions to reduce fluid velocity, a distribution header to split the fluid among lower and upper pipes with expansion zones, and downcomers to allow pressure reduction and separation of entrained liquids, enabling efficient gas-liquid separation while reducing material and weight demands.
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 and material requirements become impractical at depths greater than 1500 meters
Solution Approach 1:
The separator is divided into multiple segments including an inlet section, a separation section with internal structures, and an outlet section. This segmentation allows each part to be optimized independently, reducing the overall wall thickness requirements while maintaining separation effectiveness at deepwater pressures
Solution Approach 2:
The invention transitions from traditional horizontal cylindrical separators to a vertical orientation with internal stratification structures. This dimensional change allows gravity separation to function effectively under high pressure conditions by creating distinct gas and liquid zones within the vertical space
2Stress or pressure
If vessels with large wall thickness are used to withstand deepwater pressure, then pressure resistance is improved, but fabrication difficulty and project economics worsen
Solution Approach 1:
The design changes the geometric parameters of the separator, using a vertical cylindrical configuration with optimized diameter and height ratios. This parameter optimization reduces the required wall thickness for a given pressure rating, making fabrication more feasible while maintaining pressure resistance
Solution Approach 2:
The separator employs composite construction methods with internal linings and external reinforcement structures. This allows the use of thinner wall materials that are easier to fabricate while still achieving the required pressure resistance through the composite structure
3Stress or pressure
If vessels with large wall thickness are used, then pressure containment is improved, but added material and weight impact project economics and maintenance availability
Solution Approach 1:
The separator is designed as a modular segmented structure that can be assembled on the seabed. This segmentation reduces the weight of individual components that need to be lifted and installed, while the complete assembled structure provides the required pressure containment capability
Solution Approach 2:
The vertical orientation of the separator optimizes the weight distribution and structural efficiency under deepwater pressure. The vertical design with optimized height-to-diameter ratio reduces the overall material requirements compared to traditional horizontal designs
4Productivity
If large diameter separators are used, then separation capacity is improved, but they cannot be used at depths greater than 1500 meters due to wall thickness constraints
Solution Approach 1:
The invention uses a vertical cylindrical separator design that maximizes separation capacity in the vertical dimension rather than requiring large horizontal diameter. The internal stratification structures create sufficient separation zones within the vertical space, achieving high productivity without the wall thickness penalties of large diameter horizontal designs at deepwater pressures
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 separates production fluids into gas and liquid streams, reducing the risk of plugging and corrosion, increasing reservoir drive, and decreasing infrastructure and energy needs, while allowing for the use of single-phase pumps and reducing topside water treatment requirements.
Implementation Method 1
the inlet line includes a number of divisions configured to lower a velocity of the multiphase fluid
Implementation Method 2
The expansion zones are configured to lower a pressure within the lower pipes to allow entrained liquids to drain from the upper pipes via a corresponding downcomer
Implementation Method 3
However, subsea separation at water depths greater 1500 meters becomes especially challenging due to the environmental conditions
Data Source
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 number of divisions within a multiphase separation system, wherein the divisions are configured to lower a velocity of the multiphase fluid. The method also includes separating the multiphase fluid among a number of lower pipes and a number of upper pipes, wherein each lower pipe includes an expansion zone configured to lower a pressure within the lower pipe to allow entrained liquids to drain from a corresponding upper pipe via a downcomer.