Fractured Gas Reservoir Stress Sensitivity From Quasi-Time Analysis
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Solution Overview
Problem
Current methods lack a quantitative index for evaluating stress sensitivity in fractured gas reservoirs, particularly for carbonate reservoirs with complex fracture systems, and existing experimental methods are inadequate for accurately assessing stress sensitivity characteristics.
Innovation Solution
A stress sensitivity analysis method using normalized quasi-pressure and quasi-time, involving material balance calculations, iterative optimization, and stress sensitivity coefficients to determine the stress sensitivity of fractured gas reservoirs, providing a quantitative evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If core experiments are conducted on fractured reservoirs, then stress sensitivity characteristics can be evaluated, but it is difficult to obtain cores with developed fractures and the experiments can only reflect small fractures or porous reservoirs
Solution Approach 1:
The patent replaces physical core experiments (mechanical system) with a mathematical model-based analysis method. The stress sensitivity coefficient is calculated using production data, pressure data, and material balance equations rather than physical rock samples, thus eliminating the difficulty of obtaining cores with developed fractures while maintaining evaluation accuracy
Solution Approach 2:
The patent introduces a stress sensitivity coefficient (α) as an intermediary parameter that connects production data, pressure data, and reservoir characteristics. This coefficient serves as a mediator that allows indirect evaluation of stress sensitivity without direct physical experimentation on fractured cores
2Loss of information
If existing experimental methods are used for stress sensitivity evaluation, then some qualitative assessment can be obtained, but there is no recognized quantitative index for evaluating stress sensitivity
Solution Approach 1:
The patent transforms the stress sensitivity evaluation from qualitative to quantitative by introducing a specific parameter - the stress sensitivity coefficient (α). This coefficient is derived from production data, pressure data, and material balance calculations, providing a numerical measure that enables precise quantitative assessment rather than qualitative judgment
Solution Approach 2:
The patent establishes a feedback mechanism where the stress sensitivity coefficient is calculated iteratively by comparing material balance equations with actual production data. The coefficient is refined through successive calculations until convergence is achieved, ensuring accurate quantitative evaluation through continuous feedback validation
Data Source
AI summary
A stress sensitivity analysis method for a fractured gas reservoir includes: S1, calculating a material balance quasi-time; S2, calculating a normalized production; S3, calculating a single well controlled reserve; S4, analyzing and judging a stress sensitivity. Based on the normalized quasi-pressure and quasi-time, the gas well test analysis is carried out, and the stress sensitivity of the actual reservoir is determined by taking the original bottom hole flowing pressure of the actual reservoir as the starting point, the obtained reservoir stress sensitivity is more in line with the actual situation of the reservoir, and the obtained reservoir stress sensitivity is more accurate, which provides more valuable values for reservoir protection, oilfield development, and development planning.