Leakage Detection in Pipe Annulus Using Constant Pressure Differential
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Solution Overview
Problem
Current methods for detecting and quantifying leakage in oil and gas wells are time-consuming and prone to errors, requiring extensive calculations and potentially inaccurate measurements, with existing methods taking up to 24 hours and only providing average leakage rates over a pressure interval.
Innovation Solution
A method and apparatus utilizing a measuring arrangement with a flow meter, pressure gauge, and pressure-regulating valve to maintain a constant pressure difference across the leakage site, combined with an acoustic device for liquid level detection and a gas analyzer for real-time gas composition analysis, allowing for direct and accurate measurement of leakage rates without the need for a separate separation container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure build-up analysis is used to measure leakage rate, then leakage rate can be determined, but measurement time becomes excessively long (up to 24 hours or more)
Solution Approach 1:
The patent transforms the static pressure build-up method into a dynamic measurement process by maintaining a constant pressure difference across the leakage site using a pressure-regulating valve. This allows continuous real-time measurement of leakage rate through a flow meter, eliminating the need for lengthy pressure build-up periods while providing accurate dynamic data on leakage characteristics.
Solution Approach 2:
The patent changes the measurement parameter from pressure build-up rate to direct flow rate measurement under constant pressure difference. By controlling the pressure differential as a constant parameter and measuring the resulting flow directly, the system achieves rapid accurate measurement without the time-consuming pressure build-up analysis.
2Measurement precision
If annulus pressure is bled to zero for measurement, then gas volume can be determined, but production shutdown is required and measurement process becomes complex
Solution Approach 1:
The patent utilizes the existing annulus space and pressure conditions to perform measurements without requiring pressure reduction to zero. The system works with the annulus in its normal pressurized state, eliminating the need for production shutdown and complex bleeding procedures while still achieving accurate leakage rate measurement through direct flow measurement.
3Measurement precision
If separate separation container is used for gas-liquid separation, then accurate leakage measurement is possible, but equipment size and complexity increase
Solution Approach 1:
The patent makes the annulus serve multiple functions: it acts as both the containment space for the leakage measurement and as the gas-liquid separation chamber. By utilizing the annulus geometry and natural gas-liquid separation properties, the system eliminates the need for separate separation equipment while maintaining measurement accuracy through the integrated measuring arrangement.
Solution Approach 2:
The patent combines the separation function with the measurement function by integrating the flow meter and pressure gauge directly into the annulus system. The measuring arrangement is positioned to utilize the annulus as the separation chamber, merging multiple functions into a single integrated system that reduces overall equipment complexity.
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 faster, more reliable, and accurate measurement of leakage rates, eliminating the need to bleed annulus pressure to zero and allowing for simultaneous detection of gas and liquid leakage, reducing measurement time and equipment size while improving accuracy and accessibility.
Implementation Method 1
a flow meter for gas from the annulus constituting the separation chamber
Implementation Method 2
a pressure gauge connected to pressure sensors arranged to measure a pressure difference between annuli surrounding either side of a fluid leakage site
Implementation Method 3
a pressure-regulating valve arranged downstream of the measuring arrangement for providing a constant pressure difference between the annuli surrounding either side of the leakage site
Implementation Method 4
an acoustic measuring device able to detect the level of a liquid surface in the separation chamber
Implementation Method 5
a gas analyser arranged to be able to show at least some of the gas characteristics in real time
Implementation Method 6
conveying fluid in gas phase from the annulus connected to the measuring arrangement through the measuring arrangement, said annulus being utilised as a separation chamber for gas and liquid
Data Source
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AI summary
The present invention relates to a method and an apparatus to investigate and quantify a leakage rate for a fluid (FG, FL) between a first pipe (5) and a second pipe (7), the first pipe (5) being surrounded by at least a portion of the second pipe (7), where the pipes (5, 7) are arranged in a well (1) in a ground and where a measuring arrangement (20) including a flow meter (24) and a pressure meter (26) is put into fluid communication with an annulus (B) defined by the first pipe (5) and the second pipe (7), where fluid (FG) in the gaseous phase is conveyed through the measuring arrangement, as the annulus (B) is used as a separation chamber for gas (FG) and liquid (FL).