Subsea Pump Startup Pressure Drop Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The startup of subsea pumps in offshore hydrocarbon reservoirs causes sudden pressure drops, which can lead to reservoir damage, especially in high-pressure, low permeability reservoirs, due to the introduction of low pressure transients upstream and high pressure transients downstream.
Innovation Solution
A method involving a subsea pump system with a choke valve and recirculation loop is implemented, where the choke valve is partially closed during startup, and fluid is directed through a recirculation loop and eventually a bypass loop to manage pressure drops, allowing the subsea pump to start up gradually while minimizing pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the subsea pump is started at minimum supply frequency (25 Hz, 1500 RPM) to control umbilical temperature, then the umbilical temperature is controlled, but a sudden pressure drop occurs upstream of the pump causing reservoir damage
Solution Approach 1:
A recirculation loop is established before pump startup to maintain fluid flow and pressure in the system. The recirculation valve is opened prior to pump startup to create a bypass path that prevents sudden pressure drops when the pump begins operation, while allowing the pump to start at the required minimum frequency for umbilical temperature control
Solution Approach 2:
The recirculation loop acts as an intermediary path that mediates between the pump startup requirements and the reservoir protection needs. By providing an alternative flow path through the recirculation valve, the system can maintain stable upstream pressure during pump startup while still achieving the necessary pump operation for temperature control
2Stress or pressure
If the subsea pump speed is increased to reduce pressure drop effects, then pressure stability improves, but power loss in the umbilical increases due to lower frequency operation
Solution Approach 1:
The system dynamically adjusts the recirculation valve opening during startup to optimize the balance between pressure stability and power efficiency. The recirculation valve is opened more during initial startup to stabilize pressure, then gradually closed as the pump reaches optimal speed, minimizing energy loss while maintaining pressure control
Data Source
AI summary
Disclosed are fluid handling systems and methods for mitigating the effects of pressure drops that occur at the startup of subsea pumps associated with liquid producing reservoirs. The systems and methods are particularly useful in conjunction with subsea pumps used for producing liquids from high-pressure, low permeability hydrocarbon reservoirs. The systems and methods can mitigate damage to reservoir completions and reservoirs caused by high pressure transients downstream of the pump. A choke valve is used to restrict the flow of the liquids prior to the startup of the subsea pump. After the start of the subsea pump, the choke valve is gradually opened while a recirculation valve is gradually closed, and a full bore valve is opened.