Portable Automated Annulus Free-Volume Testing for Flexible Risers

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Solution Overview

Problem

Existing annulus free volume testing in flexible risers is costly, prone to human errors, and requires permanent installations, leading to infrequent and inaccurate testing due to long test durations.

Innovation Solution

A portable, automated unit for annulus free volume determination, comprising a container with a flow arrangement, valves, pressure instruments, and a logic unit, which automatically calculates the free volume based on pressure differences and gas addition/removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual annulus testing is performed by specialized personnel, then measurement capability is available, but testing cost increases and human errors occur

Engineering Contradiction:
Improveannulus free volume measurement accuracyVSAvoidautomation level of testing
Core Design Contradiction:
Measurement precisionVSExtent of automation

Solution Approach 1:

The system performs self-measurement of annulus free volume using automated data collection from pressure and flow sensors, eliminating the need for manual intervention while maintaining measurement accuracy. The microprocessor automatically processes the data and determines the free volume based on collected measurements.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Manual mechanical testing procedures are replaced with an automated electronic system that uses sensors, a microprocessor, and automated data processing to perform measurements, thereby reducing human error and operational costs while maintaining precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If permanent installation systems are used for annulus monitoring, then continuous monitoring capability is provided, but portability and installation flexibility are reduced

Engineering Contradiction:
Improvemonitoring capabilityVSAvoidportability and installation flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system is designed to be universally applicable and portable, capable of being installed at different locations along the riser as needed. It provides reliable monitoring capability while maintaining installation flexibility, allowing it to serve multiple testing locations without permanent fixed installation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The monitoring system is divided into modular components that can be independently installed and positioned at different locations along the riser, enabling portability and flexible installation while maintaining continuous monitoring capability through distributed sensor placement.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If long test duration is used to compensate for low data analysis accuracy, then measurement thoroughness is improved, but productivity decreases

Engineering Contradiction:
Improvedata analysis accuracyVSAvoidtesting efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

Manual data analysis is replaced with automated microprocessor-based data processing that quickly and accurately determines annulus free volume from sensor measurements, improving both accuracy and speed simultaneously rather than requiring extended test durations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system continuously collects pressure and flow data and provides real-time feedback to the microprocessor for immediate analysis, enabling rapid determination of annulus free volume without requiring prolonged test durations to ensure measurement thoroughness.

Inventive Principle:
Principle #23Feedback

4Reliability

If frequent annulus testing is performed, then integrity monitoring is improved, but availability of specialized personnel becomes a limiting factor

Engineering Contradiction:
Improveintegrity monitoring frequencyVSAvoiddependence on specialized personnel
Core Design Contradiction:
ReliabilityVSExtent of automation

Solution Approach 1:

The system performs self-testing and self-measurement of annulus free volume without requiring specialized personnel for each test execution. Only initial setup and data retrieval are needed, enabling frequent automated integrity monitoring independent of personnel availability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The need for specialized personnel is replaced with an automated electronic system that performs all measurement and analysis functions automatically, allowing frequent testing to be conducted without being constrained by the availability of trained staff.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 efficient, accurate, and frequent annulus testing without the need for specialized personnel or permanent installations, reducing test duration and human error.

Implementation Method 1

The arrangement introduces a pressure difference in the annulus and calculates the free annulus volume based on the introduced pressure difference and the amount of gas which is removed or added in the annulus volume

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Implementation Method 2

at least one pressure instrument connected between the annulus volume and the at least one valve

Methodology Applied
Scientific EffectPressure measurement:

Implementation Method 3

The at least one logic unit is configured to calculate the annulus free volume based on the introduced pressure difference in annulus volume and the amount of gas added or removed from the annulus volume

Methodology Applied
Scientific EffectGas law relationship: Boyle's Law

Data Source

PatentEP3394383B1Portable arrangement for automatical annulus testing
Publication Date: 2025.07.23 SUBSEA AS
  • EP3394383B1 patent drawingFigure 1
  • EP3394383B1 patent drawingFigure 2
  • EP3394383B1 patent drawingFigure 3

AI summary

The present invention is related to integrity monitoring of an annulus free volume in a flexible riser. More specifically, the invention is related to a portable arrangement for automatic determination of the annulus free volume of a flexible riser. The invention is also related to a method of determination of an annulus free volume in a riser, by use of the portable automated unit.