Fiber Optic Leak Detection via Digital Profile Filtering
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Solution Overview
Problem
Current methods for identifying and localizing gas leaks in oil or gas wells are inefficient, requiring lengthy serial data acquisition and often missing low leak rates due to poor signal quality and slow data collection, which can result in substantial downtime and costs for repair.
Innovation Solution
A method involving the acquisition of static and dynamic profiles using fiber optic cable assemblies with coherent Rayleigh, digital temperature sensing, and digital noise array data, followed by digital processing to filter out non-migration events, enabling timely and accurate identification of fluid migration profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If serial data acquisition with single microphone is used, then device complexity is reduced, but measurement precision and reliability deteriorate due to poor signal quality and inability to capture low leak rates
Solution Approach 1:
The wellbore is divided into multiple depth segments, with acoustic sensors distributed at different locations. This segmentation allows simultaneous monitoring of multiple zones, improving detection accuracy without requiring complex serial acquisition systems.
Solution Approach 2:
A distributed acoustic sensing system using fiber optic cables serves as an intermediary between the leak source and detection equipment. The fiber optic cable acts as both the sensing medium and data transmission channel, simplifying the overall system while improving measurement precision through continuous spatial sampling.
2Measurement precision
If serial data acquisition with frequent repositioning is used, then measurement precision improves, but productivity deteriorates due to lengthy logging time of 6-12 hours
Solution Approach 1:
The distributed acoustic sensing system enables continuous monitoring of the entire wellbore simultaneously, eliminating the need for repeated positioning and recording intervals. This continuous action maintains high measurement precision while dramatically reducing logging time from hours to minutes.
Solution Approach 2:
The system transitions from one-dimensional serial measurement (single point at a time) to multi-dimensional parallel measurement (multiple points simultaneously along the wellbore length). This dimensional change allows comprehensive coverage without the time penalty of sequential sampling.
3Measurement precision
If recording interval is extended to capture low leak rates, then measurement precision improves, but loss of time increases due to prolonged stabilization and recording periods
Solution Approach 1:
The system maintains continuous acoustic monitoring along the entire wellbore, allowing detection of low leak rates without requiring extended recording intervals at discrete points. The continuous spatial coverage ensures that even rare leak events are captured promptly.
Solution Approach 2:
The fiber optic cable is pre-deployed throughout the wellbore before logging begins, with acoustic sensing capability already in place at all depths. This preliminary preparation eliminates the need for time-consuming stabilization periods and enables immediate detection of low leak rates upon activation.
4Reliability
If multiple sensors are deployed simultaneously, then measurement precision and reliability improve, but device complexity and cost increase
Solution Approach 1:
The fiber optic cable serves multiple functions simultaneously: it acts as the structural support, the acoustic sensing medium, and the data transmission channel. This multi-functionality enables reliable leak detection with multiple sensing points without proportionally increasing system complexity.
Solution Approach 2:
The fiber optic cable serves as an intermediary that integrates multiple sensing functions into a single unified system. Rather than deploying separate sensors that would increase complexity, the fiber optic medium provides distributed sensing capability while simplifying the overall system architecture.
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
This approach significantly reduces the time required to detect and localize leaks, improving the accuracy of gas migration profiling and enabling quicker repair, thus minimizing downtime and costs for oil and gas producers.
Implementation Method 1
coherent Rayleigh data
Implementation Method 2
digital noise array data
Data Source
AI summary
The method for obtaining a fluid migration profile for a wellbore, including the steps of obtaining a static profile for a logged region of the wellbore, obtaining a dynamic profile for the logged region of the wellbore, digitally filtering the dynamic profile to remove frequency elements represented in the static profile, to provide a fluid migration profile, and storing the fluid migration profile on a computer-readable memory.