Subsea Pump Pressure Control to Limit Fluid Hammer
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Solution Overview
Problem
Existing subsea drilling systems experience fluid hammer, which can lead to hydraulic pressure spikes and component failure due to uncontrolled pressure differentials.
Innovation Solution
A pumping system with independent pump control and pressure regulation, utilizing sensors and motors to manage pressure differentials and limit fluid hammer by de-stroking pumps when predetermined pressures are reached, and a manifold system with pressure monitoring and dump valves to isolate pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pumps operate at high pressure to meet drilling demands, then productivity is improved, but fluid hammer and pressure spikes increase causing component failure
Solution Approach 1:
The system dynamically adjusts pump stroke volume and frequency based on real-time pressure differential feedback. When pressure differential approaches threshold values, the control system reduces pump output dynamically, preventing fluid hammer while maintaining high productivity during normal operation. This dynamic adaptation resolves the contradiction between maintaining high productivity and preventing component failure.
Solution Approach 2:
Pressure differential sensors continuously monitor the system and provide feedback to the pump control system. When the differential between pump discharge pressure and control pod pressure exceeds predetermined thresholds, the feedback mechanism triggers pump de-stroking or shutdown, preventing harmful pressure spikes. This closed-loop feedback ensures both high productivity during normal operation and component protection during abnormal conditions.
2Speed
If pressure differentials are increased to improve valve actuation speed, then operation speed is improved, but fluid hammer increases causing harmful effects
Solution Approach 1:
Before actuating control pod valves, the system preliminarily positions pumps to provide optimal pressure differentials. The control system pre-charges the hydraulic lines to appropriate pressure levels, ensuring valves can actuate quickly when needed while preventing excessive pressure differentials that would cause fluid hammer. This preliminary preparation maintains fast response without harmful effects.
Solution Approach 2:
The system changes operational parameters dynamically based on system state. Pressure differential thresholds are adjusted according to operating conditions, allowing higher differentials (faster actuation) when safe, and lower differentials (slower actuation) when approaching harmful levels. This parameter adaptation resolves the contradiction between speed and harmful effects.
3Reliability
If pump pressure is continuously maintained at high levels to ensure system readiness, then reliability is improved, but energy consumption increases and fluid hammer risk increases
Solution Approach 1:
Instead of continuous high-pressure operation, the system uses periodic pump cycling with de-stroking between operations. Pumps operate at high pressure only when needed for valve actuation or system testing, then de-stroke to low pressure for extended periods. This periodic action maintains system readiness reliability while dramatically reducing energy consumption and fluid hammer exposure time.
Solution Approach 2:
The system extracts the continuous high-pressure requirement and replaces it with on-demand pressure generation. Pumps are taken out of continuous operation and engaged only when pressure is needed, using de-stroking technology to rapidly transition between operational states. This extraction of continuous operation eliminates unnecessary energy consumption while maintaining reliability through rapid response capability.
4Object-affected harmful factors
If de-stroking is used to reduce fluid hammer, then harmful effects are reduced, but pump control complexity increases
Solution Approach 1:
The pump control system automatically manages de-stroking operations based on simple pressure differential threshold inputs. Once thresholds are set, the system self-regulates pump stroke volume and frequency without requiring complex external control logic. This self-service approach reduces fluid hammer while minimizing the complexity of external control systems.
Solution Approach 2:
A pressure differential sensor acts as an intermediary between the pump and control pod, translating complex pressure conditions into simple threshold-based control signals. This intermediary device simplifies the control logic by providing clear go/no-go signals based on predetermined pressure differentials, reducing overall system complexity while effectively managing fluid hammer.
Data Source
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AI summary
A pumping system includes a plurality of pumps, each having an inlet and an outlet. The inlet is fluidly coupled to a hydraulic fluid reservoir. The outlet is fluidly coupled to a control pod having a valve and a pair of sensors monitoring upstream and downstream pressures of the valve. The control pod is fluidly coupled to a subsea blowout preventer. A first motor is coupled to a first pump of the plurality of pumps and sets the first pump at a first predetermined pressure. A controller is coupled to and configured to control the first motor, thereby controlling the first pump. The pumping system is configured to: engage and disengage each pump independently; and destroke each pump to limit pressure to the valve, when a predetermined pressure for each pump is attained, thereby reducing fluid hammer at the control pod.