Pulse-Decay Permeability Leak Correction
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Solution Overview
Problem
Accurate measurement of permeability in low permeability rock formations is challenging due to leakage issues in laboratory testing, which can significantly impact the assessment of tight rock formations like shales, affecting the prediction of reservoir productivity and profitability.
Innovation Solution
The pulse-decay permeability (PDP) method involves analyzing pressure changes over time in a sealed enclosure to determine fluid leakage, allowing for the correction of permeability measurements by fitting non-straight curves and accounting for leakage effects, thereby preserving the rock sample structure and reflecting anisotropic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional permeability measurement methods are used on low permeability rock formations, then the measurement process is simple, but the measurement accuracy is low due to leakage issues
Solution Approach 1:
The patent implements feedback by continuously monitoring pressure changes in the sealed enclosure during the pulse-decay experiment. The system measures pressure at multiple time points and uses this feedback information to detect leakage and correct permeability measurements, thereby improving measurement accuracy while managing system complexity through intelligent control.
Solution Approach 2:
The patent replaces traditional mechanical leakage detection methods with a pressure-based detection system. By monitoring pressure changes over time in the sealed enclosure and analyzing the pressure decay curve, the system can detect leakage without complex mechanical sensors or additional hardware, thus improving measurement precision without proportionally increasing device complexity.
2Reliability
If repeated experiments are performed to ensure accurate measurements, then measurement reliability improves, but time consumption and sample damage increase
Solution Approach 1:
The patent converts the harmful effect of leakage into a beneficial detection mechanism. By analyzing pressure decay curves and identifying characteristic patterns that indicate leakage, the system can detect and correct for leakage effects mathematically, eliminating the need for repeated experiments and reducing time loss while maintaining or improving measurement reliability.
Solution Approach 2:
The patent changes the approach from physical repetition of experiments to mathematical parameter analysis. By analyzing pressure change parameters over time and applying correction models, the system achieves reliable measurements without repeating experiments, thereby reducing time consumption while maintaining measurement reliability.
3Measurement precision
If conventional measurement methods are used, then the process is quick, but leakage cannot be detected leading to inaccurate results
Solution Approach 1:
The patent performs preliminary action by sealing the enclosure and establishing baseline pressure conditions before conducting the permeability measurement. This preliminary setup enables the system to detect leakage during the experiment by comparing actual pressure decay against expected decay patterns, making leakage detection integrated into the measurement process rather than requiring separate detection steps.
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 method effectively corrects for leakage in permeability measurements, providing more accurate estimates of rock formation permeability, reducing the need for repeated experiments and preserving the rock sample structure, thus enhancing the assessment of tight rock formations.
Implementation Method 1
a pulse-decay permeability (PDP) experiment is performed on a core sample retrieved from a formation. The PDP experiment includes flowing fluid through the core sample in a sealed enclosure. In response to flowing the fluid through the core sample, a change in fluid pressure is measured over time.
Data Source
AI summary
A method for correcting low permeability laboratory measurements for leaks. A pulse-decay permeability (PDP) experiment is performed on a core sample retrieved from a formation. The PDP experiment includes flowing fluid through the core sample in a sealed enclosure. In response to flowing the fluid through the core sample, a change in fluid pressure is measured over time. Based on the change in fluid pressure over time, a leakage of fluid from the sealed enclosure is determined. In response to determining the leakage of fluid from the sealed enclosure, an analytical model of the leakage is determined based on the change in fluid pressure over time.