Subsea Well Shutdown Processor Segmentation
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Solution Overview
Problem
Current systems for controlling the shutdown of underwater fluid production wells are lengthy, complex, and have low reliability due to the need for communication between the wellhead and the surface, leading to a high probability of failure, which is inadequate for achieving even the lowest safety integrity level (SIL) rating.
Innovation Solution
Implementing a local subsea production shutdown processing function using a SIL-rated processor at the wellhead that can detect fault conditions and initiate shutdown without surface communication, allowing for both autonomous and surface-commanded shutdowns, with a backup system to ensure reliability even in case of communication or power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface-controlled shutdown system is used with communication via umbilical cable, then the well can be shut down with surface monitoring and control, but the shutdown time is extended and reliability is reduced due to communication delays and potential failures
Solution Approach 1:
The shutdown control function is segmented into two independent parts: a surface control system for normal operations and a local subsea control system for autonomous shutdown. The subsea control module includes local sensors, processor, and actuators that can detect fault conditions and initiate shutdown without waiting for surface communication, thereby reducing shutdown time and improving reliability.
Solution Approach 2:
The subsea control system is pre-configured with shutdown logic and control algorithms before deployment. When a fault condition is detected by local sensors, the pre-programmed processor immediately triggers the shutdown sequence through local actuators, eliminating the need for real-time surface communication and reducing both shutdown time and communication-related failures.
2Reliability
If surface communication is required for shutdown control, then centralized monitoring is maintained, but system complexity increases and probability of failure increases
Solution Approach 1:
The control system is divided into modular components: surface control module for normal operations, subsea control module for autonomous shutdown, local sensors for fault detection, and communication interface for coordinated operation. This segmentation reduces overall system complexity while improving reliability by isolating the critical shutdown function from surface communication dependencies.
Solution Approach 2:
The subsea control system is designed to be self-sufficient for shutdown operations, with local sensors detecting fault conditions and the local processor automatically initiating shutdown through local actuators. This self-service capability eliminates dependency on surface communication for critical shutdown functions, reducing system complexity and failure probability.
3Productivity
If autonomous subsea control is implemented, then shutdown reliability and speed are improved, but the ability for surface monitoring and control is reduced
Solution Approach 1:
The subsea control system continuously monitors well parameters through local sensors and provides real-time feedback to the surface control system via the communication interface. This feedback loop allows the surface to maintain monitoring capability and situational awareness while the subsea system operates autonomously for rapid shutdown response when faults are detected.
Solution Approach 2:
The control architecture segments monitoring and control functions: the subsea control module handles autonomous shutdown decisions and execution for rapid response, while the surface control module maintains overall system monitoring and receives status information through feedback. This segmentation enables both fast autonomous response and continuous surface awareness simultaneously.
Data Source
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AI summary
A system for controlling production shut down of an underwater fluid production well, the well having a sensor (9) for producing an output signal indicative of the state of the well and a valve (2) which is actuable to shut down production activity of the well, comprises means for receiving the output signal; and a processor (8) for processing the received signal to determine if a shut-down is required and outputting a shut down signal to the valve; wherein the receiving means and processor are located at the well.