Emergency Disconnect Triggering From Riser Joint Angular Offset
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Solution Overview
Problem
Conventional offshore drilling platforms are unable to execute emergency disconnect sequences quickly enough in shallow water depths, leading to potential catastrophic failures due to reduced operating tolerances and reaction time, making them unsuitable for safe operation in such conditions.
Innovation Solution
A disconnection system that includes a controller with motion reference units to determine angular offsets and send trigger signals to initiate an emergency disconnect sequence when predetermined thresholds are exceeded, allowing for rapid and automated disconnection of the vessel from the wellhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional emergency disconnect sequences are used in shallow water depths, then the system structure remains simple and reliable, but the disconnection speed is too slow to prevent catastrophic failure
Solution Approach 1:
The system performs preliminary actions by pre-positioning the disconnect mechanism and pre-charging hydraulic accumulators with pressurized fluid before an emergency occurs. When triggered, the disconnect sequence executes immediately using stored energy and pre-configured components, eliminating the need for complex real-time control systems while achieving rapid disconnection in shallow water depths
Solution Approach 2:
The invention extracts the essential disconnection function from the complex conventional EDS system, isolating the critical components (hydraulic accumulators, disconnect mechanism, trigger system) needed for rapid separation. This simplified extracted system achieves the required disconnection speed without the complexity of full conventional emergency disconnect sequences
2Reliability
If the vessel operates in shallow water depths, then the operating circle is reduced and safety margins decrease, but the conventional EDS cannot execute fast enough to compensate
Solution Approach 1:
The system implements beforehand cushioning by pre-storing hydraulic energy in charged accumulators and pre-positioning the disconnect mechanism in a ready state. This preparatory cushioning of energy and mechanical configuration enables the system to execute disconnection instantly when triggered, compensating for the reduced reaction time available in shallow water operations and maintaining operating safety
Solution Approach 2:
The disconnect system is designed to be self-service through automatic trigger detection and self-execution of the disconnect sequence. The system monitors its own state, automatically detects emergency conditions (such as excessive angular offset), and executes disconnection without requiring external intervention or complex control systems, thereby reducing response time and improving reliability in shallow water depths
Data Source
AI summary
Systems and methods for initiating an emergency disconnect sequence (EDS) are provided. In an aspect, a disconnection system is provided and configured to initiate the EDS, and includes a controller including a processor and a memory operably coupled to the processor. The controller receives, from a set of motion reference units (MRU(s)) operably coupled to a flexible joint, position data generated by the set of motion references units and associated with the joint when the joint is operably coupled to and disposed between a drilling riser and a lower marine riser package (LMRP). The controller determines, based on the position data, an angular offset of the joint. The controller sends, to a subsea control pod disposed at or adjacent to the LMRP, a trigger signal in response to determining that the angular offset exceeds a predetermined threshold, such that the subsea control pod initiates the EDS.