Fluid Substitution Using P-Wave Velocity and Well Log Corrections
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Solution Overview
Problem
The existing Gassmann fluid substitution method is limited by the need for extensive rock properties data, invalid assumptions about rock homogeneity and fluid flow, reliability issues with carbonate rocks, and requirement for detailed rock physics knowledge, leading to errors and restricted accessibility.
Innovation Solution
A simpler and more robust fluid substitution method that calculates the difference between initial and substituted geophysical parameters using a rock physics model, allowing for indirect calculation and reducing reliance on direct model outputs, which can be calibrated with readily available data and does not require s-wave velocity data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Gassmann fluid substitution method is used, then fluid substitution can be performed, but it requires extensive rock properties data and detailed rock physics knowledge
Solution Approach 1:
The patent extracts and removes the requirement for s-wave velocity data from the fluid substitution process. By using only p-wave velocity data and well log data, the method eliminates the need for complex shear modulus calculations and s-wave measurements, significantly simplifying the data requirements while maintaining substitution accuracy
Solution Approach 2:
The patent creates a universal fluid substitution method that works for both siliciclastic and carbonate rocks using the same approach. The method uses p-wave velocity and well log data universally across different rock types, eliminating the need for rock-type-specific parameters and detailed rock physics knowledge that previously limited applicability
2Reliability
If Gassmann fluid substitution method is used, then fluid substitution can be performed, but it requires p-wave and s-wave velocities and bulk modulus of rock material
Solution Approach 1:
The patent removes the requirement for s-wave velocity data and bulk modulus of rock material from the input parameters. The method achieves fluid substitution using only p-wave velocity and well log data, extracting the essential information needed while eliminating redundant or difficult-to-obtain parameters
Solution Approach 2:
The patent adopts an asymmetric approach by relying primarily on p-wave velocity data rather than requiring both p-wave and s-wave velocities. This asymmetric data requirement simplifies the input needs while maintaining the ability to perform accurate fluid substitution through the use of well log corrections
3Ease of manufacture
If Gassmann fluid substitution method is used, then fluid substitution can be performed, but it assumes rock homogeneity and free fluid flow which are not always valid
Solution Approach 1:
The patent changes the approach from directly applying Gassmann equations with fixed assumptions to using a correction factor methodology. By introducing a correction factor that accounts for deviations from ideal Gassmann behavior, the method maintains simplicity while adapting to real-world conditions where rock homogeneity and free fluid flow assumptions may not hold
Solution Approach 2:
The patent incorporates feedback by using well log data to correct and calibrate the fluid substitution results. The well log measurements provide feedback on actual rock properties, allowing the method to adjust for deviations from Gassmann assumptions and improve reliability for complex rock types like carbonates
4Ease of operation
If Gassmann fluid substitution method is used, then fluid substitution can be performed, but it gives large errors when Gassmann assumptions are violated
Solution Approach 1:
The patent uses well log data as feedback to correct fluid substitution results. By comparing predicted properties with actual well log measurements and applying corrections, the method maintains high accuracy even when Gassmann assumptions are violated, while keeping the overall approach accessible and easy to operate
Solution Approach 2:
The patent changes the methodology from direct Gassmann calculation to a corrected approach using p-wave velocity and well log data. This parameter change allows the method to accommodate violations of Gassmann assumptions while maintaining simplicity and accessibility for practical application
Data Source
AI summary
A method of fluid substitution, wherein an initial data set is provided, wherein a substituted data set is provided, wherein a rock physics model is provided, wherein the initial data set includes initial data of a geophysical parameter and initial fluid data, and wherein the substituted data set includes substituted fluid data. The method includes using the model and the initial data set to calculate first calculated data of the geophysical parameter, using the model and the substituted data set to calculate second calculated data of the geophysical parameter, calculating the difference between the first calculated data of the geophysical parameter and the second calculated data of the geophysical parameter, and applying the difference to the initial data of the geophysical parameter to produce substituted data of the geophysical parameter.