Subsea Mixing Module for Multiphase Stream Distribution
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Solution Overview
Problem
Existing oil exploration and production systems face inefficiencies due to the lack of direct interconnection between Stationary Production Units (SPUs), leading to bottlenecks in oil, water, or gas processing capacity, resulting in energy inefficiencies, high installation costs, and opportunity costs in oil and gas production.
Innovation Solution
An engineering and control arrangement that manages the multiphase distribution of underwater currents from oil wells by using single-phase fluid outlets from subsea separation equipment, which are then mixed in a controller-assisted manner to optimize the processing capacity of SPUs, utilizing the capacitance of the separator vessel to dampen pressure disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluids are sent from one SPU to another to resolve processing bottlenecks, then the processing capacity utilization is improved, but energy efficiency deteriorates due to depressurization and repressurization
Solution Approach 1:
A subsea mixing module acts as an intermediary between the phase separator and multiple SPUs. It receives single-phase streams (gas, oil, water) from the separator, mixes them in controlled proportions, and distributes the multiphase mixture to multiple SPUs. This eliminates the need for surface-level fluid transfer between SPUs, avoiding depressurization-repressurization cycles and associated energy losses.
Solution Approach 2:
The invention replaces the mechanical system of surface-level fluid pumping and repressurization with a subsea-based mixing and distribution system. By performing phase mixing at subsea level using the natural pressure of the separator, the system eliminates the need for energy-intensive repressurization equipment that would be required if fluids were transferred between SPUs at the surface.
2Productivity
If surface facilities are used to transfer fluids between SPUs, then processing bottlenecks are relieved, but installation costs increase due to additional treatment capacity requirements
Solution Approach 1:
The subsea mixing module serves as an intermediary that consolidates the need for treatment capacity. Instead of requiring each SPU to have excess treatment capacity to receive transferred fluids, the mixing module prepares optimized multiphase streams that match the specific processing capabilities of each target SPU, eliminating the need for redundant treatment infrastructure.
Solution Approach 2:
The system provides locally optimized fluid compositions for each SPU based on their specific processing needs. The mixing module can create different multiphase stream compositions for different SPUs, ensuring each receives fluids matched to its processing capacity, thereby eliminating the need for universal over-capacity treatment facilities at each SPU.
3Productivity
If surface facilities are used to transfer fluids between SPUs, then processing bottlenecks are relieved, but opportunity costs increase due to utilization of processing plant space
Solution Approach 1:
The subsea mixing module acts as an intermediary that enables flexible, real-time adjustment of fluid distribution to multiple SPUs without requiring physical modifications or space allocation at the surface facilities. This maintains processing plant space available for primary production functions while still enabling bottleneck relief through dynamic subsea stream management.
Solution Approach 2:
The invention moves the fluid mixing and distribution function from the surface dimension to the subsea dimension. By performing mixing operations at subsea level rather than at surface facilities, the system utilizes the vertical dimension of the production system, freeing up surface processing plant space for its primary oil and gas processing functions while still achieving the goal of optimizing SPU utilization.
4Reliability
If sequential operation mode is used for SPUs, then reservoir management criteria are met, but some SPUs operate at partial idle capacity
Solution Approach 1:
The system dynamically adjusts the composition and distribution of multiphase streams to multiple SPUs based on real-time processing capacity requirements. This dynamic capability allows SPUs to operate at or near their optimal capacity levels while maintaining the sequential development approach for reservoir management, eliminating the idle capacity that results from static, fixed distribution patterns.
Solution Approach 2:
The subsea mixing module provides universal service to multiple SPUs, enabling a single phase separator to supply optimized fluid streams to multiple production units simultaneously. This multi-functionality allows the system to maintain sequential reservoir management while ensuring each SPU receives appropriately composed fluids matched to its specific processing capacity, preventing idle operation.
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 allows for more robust and efficient operation of SPUs, reducing operational problems and costs by optimizing the distribution of oil, gas, and water phases, thereby maximizing the processing capacity of SPUs and minimizing energy inefficiencies and installation costs.
Implementation Method 1
Some phase separation systems, such as SSGL (Submarine Gas-Liquid Separation) or SSAO (Submarine Water-Oil Separation), provide gravitational separation of fluids according to their specific masses, generating a light phase and a heavy phase.
Implementation Method 2
The engineering and control arrangement removes single-phase streams from subsea separation equipment that, mixed in a controlled manner, generate streams with specific phase distribution for the maximum use of the processing capacity of the SPUs.
Implementation Method 3
utilizing the capacitance of the separator vessel to dampen pressure disturbances
Data Source
AI summary
The present disclosure describes a control and management system of multiphase streams in subsea oil and gas production modules. The system comprises (i) a phase separator vessel; (ii) mixing lines; (iii) multiphase, single-phase, pressure, and level variation flow rate measuring instruments; (iv) flow rate and pressure sensors; (v) automatic control valves; and (vi) cascade PID pressure, level, and pressure controllers.The system control is further carried out by controlling fluid accumulation inventory, controlling the gas-liquid ratio of the stream sent to a first stationary production unit and controlling the gas-liquid ratio of the stream sent to a second stationary production unit so that a maritime field works optimally and without stoppages or bottlenecks.