Flexible Pipe Annulus Pressure Detection for Watertightness
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Solution Overview
Problem
Existing technologies struggle to efficiently detect and quantify the watertightness of the annular space in flexible lines used in offshore oil production, particularly in the pre-salt scenario of the Santos Basin, leading to potential corrosion and catastrophic failures due to water ingress, with limited applicability and inefficiencies in existing methods.
Innovation Solution
A system and method using a remotely operated vehicle (ROV) to measure pressure inside the annulus of flexible lines through a piston-cylinder arrangement, with a sealing system and pressure gauge, to determine watertightness and optionally collect fluid samples, capable of operating at various depths and line configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional inspection technologies are used to detect watertightness of flexible lines, then the detection can be performed, but the technologies have usage limitations relating to the number and thickness of layers, operating water depth, and cannot identify the source of water in the annulus
Solution Approach 1:
The patent replaces traditional mechanical inspection methods with a pressure-based detection system. A pressure sensor is installed in the annulus to continuously monitor pressure changes, which indicate water ingress. This substitution allows detection regardless of line configuration, layer thickness, or operating depth, resolving the contradiction between detection reliability and adaptability.
Solution Approach 2:
The patent introduces an intermediary pressure sensor system that mediates between the complex multi-layer flexible line structure and the detection objective. The sensor acts as an intermediary element that can be integrated into the connector without disrupting the existing line architecture, enabling reliable detection across diverse configurations and depths.
2Productivity
If pressure measurement method is used to detect watertightness, then rapid non-destructive detection is enabled, but additional equipment (ROV, piston-cylinder system) is required
Solution Approach 1:
The patent employs a self-service approach where the existing safety valve and connector infrastructure of the flexible line is utilized for pressure measurement. The detection system taps into the existing annulus space and uses the line's own structural elements (connector, safety valve) as part of the measurement apparatus, reducing the need for additional complex equipment while maintaining rapid detection capability.
Solution Approach 2:
The pressure measurement system is designed with multi-functionality, serving both as a watertightness detection device and as a potential platform for fluid sampling and analysis. The ROV-mounted system can perform multiple inspection functions, reducing the need for separate specialized equipment and justifying the initial complexity through enhanced productivity and versatility.
3Measurement precision
If fluid sampling is performed to identify water source and assess corrosiveness, then accurate diagnosis is achieved, but the process becomes more complex and time-consuming
Solution Approach 1:
The patent applies preliminary action by performing fluid sampling and analysis in advance during routine maintenance or inspection periods. The system collects and analyzes fluid samples from the annulus beforehand, establishing a baseline understanding of water sources and corrosiveness. This preliminary data is then available for rapid reference during operational monitoring, reducing the need for time-consuming on-demand sampling and analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid, non-destructive detection of watertightness and fluid sampling, reducing the risk of corrosion and failures by identifying flooded annuli, and providing accurate pressure readings regardless of depth or layer composition.
Implementation Method 1
measuring the pressure value inside the annulus of a flexible line in operation
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention relates to a system for detecting the watertightness or flooding of the annulus of flexible lines from a connector, comprising: an assembly of plunger (3) and cylinder (4) that are connected by a rod to a chamber (19) that acts as a pilot valve, connected directly to the outlet of a safety valve of a connector of the flexible line, in which same are fitted using a sealing system (6). The system is operated by commands sent to the ROV (2) that has an arm (21) and that controls the system using a handle (9). The present invention also describes the operating method of the device and how the obtained results lead to a preprogrammed conclusion regarding the watertightness (or otherwise) of the annulus. Other methods are provided to obtain fluid samples in the annulus for subsequent analysis and enable the safety valve to be removed from the connectors.