Rock Matrix and Fracture Permeability Using Multi-Frequency Elastic Waves
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Solution Overview
Problem
Existing methods struggle to accurately estimate permeability in rock formations, which is crucial for oil and gas industry applications such as production rate estimation, reservoir volume assessment, and well drilling planning.
Innovation Solution
A method using a dual porosity dual permeability poroelastodynamic model to determine rock matrix and fracture permeability by measuring elastic wave velocities at different frequencies, calculating average density and porosity, and performing a reservoir fluid flow simulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional permeability estimation methods are used, then the process is simpler and faster, but the measurement precision and reliability of permeability estimates deteriorate
Solution Approach 1:
The patent applies parameter changes by measuring elastic wave velocity at multiple different frequencies rather than a single frequency. This frequency variation allows the system to capture different aspects of fluid flow behavior in the rock formation, enabling more accurate differentiation between matrix and fracture permeability components while maintaining a practical measurement approach.
Solution Approach 2:
The patent segments the permeability measurement into two distinct components: matrix permeability and fracture permeability. By using multi-frequency elastic wave velocity measurements, the system can separately determine these two permeability components through inverse modeling, providing more detailed and accurate characterization than traditional single-value permeability estimates.
2Reliability
If multi-frequency elastic wave velocity measurements are performed, then permeability estimation accuracy improves, but the measurement time and processing complexity increase
Solution Approach 1:
The patent uses partial action by selecting specific frequency points for measurement rather than continuously sweeping through all possible frequencies. The system performs measurements at selected frequencies that provide the most information for distinguishing matrix and fracture permeability, avoiding unnecessary measurements at frequencies that would not contribute additional useful information.
Solution Approach 2:
The patent employs feedback through an iterative inverse modeling process. The system uses measured multi-frequency elastic wave velocities to update estimates of matrix and fracture permeability, then compares predicted velocities with actual measurements, and repeats the process until convergence is achieved. This feedback mechanism ensures reliable permeability estimates while systematically reducing the number of iterations needed.
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 accurate estimation of permeability, facilitating better wellbore path design and supporting economic and drilling decisions through fluid flow simulations.
Implementation Method 1
measuring a first elastic wave velocity of the formation sample at a first frequency and measuring a second elastic wave velocity of the formation sample at a second frequency
Data Source
AI summary
A method of determining rock matrix and fracture permeability to perform a reservoir fluid flow simulation. The method includes: obtaining a petrophysical characterization of a formation sample, measuring a first and second elastic wave velocity of the formation sample at a first and second frequency, calculating an average rock matrix density and an average porosity of the formation sample, determining a set of calculated elastic wave velocities for the first and second frequencies over a range of candidate permeabilities, and determining a rock matrix permeability and a fracture permeability based on the set of calculated elastic wave velocities at the first and second frequency respectively. The method further including performing a reservoir fluid flow simulation based, at least in part, on at least one of the rock matrix permeability and the fracture permeability.