Subsea Multiphase Stream Virtual Decoupling for Separator Control
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Solution Overview
Problem
Existing subsea processing systems face operational complexity due to high interdependence between control variables, leading to inefficiencies and reduced production efficiency, particularly when some Stationary Production Units (SPUs) operate at capacity while others are partially idle.
Innovation Solution
A virtual decoupling method using mass conservation laws to estimate flow rates and generate setpoints for controllers, mitigating interactions between operational variables and improving control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If subsea processing systems operate with direct interconnection between Stationary Production Units (SPUs), then fluid distribution can be simplified, but some SPUs will operate at capacity while others remain partially idle, reducing overall production efficiency
Solution Approach 1:
The patent introduces a virtual decoupling intermediary layer that acts as a mediator between SPUs and fluid distribution control. This virtual decoupler uses mathematical models to calculate optimal flow distribution, allowing indirect control that balances load across multiple SPUs while maintaining simplified physical interconnections. The intermediary processing layer enables coordinated operation without direct complex interconnections.
Solution Approach 2:
The system dynamically changes operational parameters (flow rates, pressure, temperature) of multiphase streams distributed to different SPUs. By adjusting these parameters in real-time based on SPU capacity status, the system optimizes production efficiency and prevents bottlenecking, allowing flexible load balancing across production units.
2Productivity
If a SPU reaches maximum capacity in its main subunits, then additional processing capacity is needed, but redirecting excess fluids to a second SPU generates energy loss and high installation costs
Solution Approach 1:
The virtual decoupling system performs preliminary calculations and predictions about fluid flow distribution before actual redistribution occurs. By using mathematical models to forecast capacity needs and optimize flow allocation in advance, the system prevents bottlenecking at single SPUs and avoids the need for energy-intensive emergency redistribution to second SPUs.
Solution Approach 2:
The control system provides universal functionality by managing fluid distribution to multiple SPUs through a single integrated virtual decoupling layer. This multi-functional control approach allows any SPU to serve as primary or secondary processing unit based on real-time conditions, eliminating the need for dedicated backup systems and reducing overall energy consumption.
3Reliability
If control variables in subsea processing systems are highly interdependent, then system integration is improved, but operational complexity increases and control precision decreases
Solution Approach 1:
The patent segments the highly interdependent control variables into distinct functional groups that can be managed separately through the virtual decoupling layer. By dividing the control system into modular segments (flow rate control, pressure control, temperature control, GLR management), the system maintains reliable integration while reducing operational complexity and improving control precision for each variable group.
Data Source
AI summary
The present invention refers to a virtual decoupling method for managing multiphase streams in subsea oil production modules, which comprises: obtaining, by means of flow rate transducers, the measurement of the flow rate in the valves V1, V2, V3 and V4; obtaining, by means of gas-liquid ratio transducers (GLRT), the measurement of the gas-liquid ratio of the multiphase streams at the outlets of the subsea oil production module (GLR1, GLR2); obtaining, by means of the pressure transducer PT01 and the level transducer LT01, the measurement of pressure and level in the separator vessel; obtaining, by means of the flow rate transducers FT02 and FT03, the measurement of the flow rate of the gas streams; obtaining, by means of the flow rate transducers FT01 and FT04, the measurement of the flow rate of the liquid streams; calculating the total liquid flow rate (TLF) and the total gas flow rate (TGF); adjusting the GLR values for subsea processing conditions (GLRS); and defining the setpoint of the flow rate controllers of the streams leaving the separator vessel (FIC1SP, FIC2SP, FIC3SP and FIC4SP).