Subsea BOP Control Pod Redundancy for 20,000 psi Drilling
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Solution Overview
Problem
Current subsea drilling technologies face limitations in drilling wells with pressures exceeding 15,000 pounds per square inch due to safety and environmental concerns, and existing blowout preventer (BOP) systems lack effective testing methods for hydraulic valves without requiring high-pressure cycles or extra opening and closing operations, making it difficult to ensure safety integrity level compliance.
Innovation Solution
A BOP system with a shipboard subsystem electronically, mechanically, and hydraulically connected to a subsea riser subsystem, incorporating a safety instrumented system with surface and subsea logic solvers, and an auxiliary stack test system for pre-deployment testing to ensure compliance with safety standards, allowing operation at pressures up to 20,000 pounds per square inch and temperatures up to 350 degrees Fahrenheit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If existing BOP systems are used for high pressure drilling, then drilling operations can be conducted, but safety and environmental risks increase significantly at pressures exceeding 15,000 psi
Solution Approach 1:
The patent implements pre-deployment testing of hydraulic valves using an auxiliary stack test system that simulates high-pressure conditions before the BOP is deployed to the actual well site. This preliminary testing ensures that all safety-critical components are functioning correctly before encountering real high-pressure well conditions, thereby preventing safety failures during actual drilling operations at pressures exceeding 15,000 psi.
Solution Approach 2:
The system incorporates a safety instrumented system with logic solvers that continuously monitor the operational status of BOP components and provide real-time feedback. This feedback mechanism enables the system to detect anomalies, trigger safety responses, and maintain reliable operation under high-pressure conditions by continuously verifying system integrity and responding to changing well conditions.
2Reliability
If hydraulic valves are tested using traditional methods, then valve functionality can be verified, but high-pressure cycles and extra opening/closing operations are required
Solution Approach 1:
The auxiliary stack test system creates a simplified copy of the actual BOP hydraulic system that can be tested independently on the surface or in a controlled environment. This test copy includes test manifolds and simulated high-pressure conditions that allow complete valve functionality verification without requiring the actual BOP to undergo high-pressure cycles or multiple opening/closing operations, thereby simplifying the testing procedure while maintaining testing accuracy.
3Reliability
If redundant control systems are implemented for safety, then safety integrity improves, but system complexity increases
Solution Approach 1:
The control system is segmented into distinct functional modules including a safety instrumented system with separate logic solvers, a basic control system, and an auxiliary test system. Each segment operates independently with defined interfaces, allowing the redundant safety functions to be implemented and verified without creating an unmanageably complex monolithic system. This modular segmentation enables clear allocation of safety-critical functions to dedicated hardware and software components.
Solution Approach 2:
Logic solvers serve as intermediary components between the safety instrumented system and the basic control system. These logic solvers receive inputs from various sensors and actuators, process safety-critical information according to predefined safety logic, and generate appropriate control outputs. This intermediary layer provides structured redundancy and safety verification without requiring complete duplication of the entire control system, thereby managing complexity while maintaining safety integrity.
Data Source
AI summary
A blowout preventer system including a lower blowout preventer stack comprising a number of hydraulic components, and a lower marine riser package comprising a first control pod and a second control pod adapted to provide, during use, redundant control of hydraulic components of the lower blowout preventer stack where the first and the second control pods are adapted to being connected, during use, to a surface control system and to be controlled, during use, by the surface control system. The blowout preventer system further including at least one additional control pod connected to at least one additional surface control system and to be controlled, during use, by the additional surface control system.