Multi-Frequency Dielectric Logging for Formation Exponents
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Solution Overview
Problem
Conventional methods for determining formation textural parameters in downhole exploration and production are limited by assumptions about saturation variation and constant formation pore structure or rock type, leading to inaccurate estimates of cementation and saturation exponents, which affect oil reserve estimation.
Innovation Solution
A method utilizing multi-frequency dielectric data to estimate cementation and saturation exponents by applying dielectric mixing models between fluid phases and the matrix, minimizing differences between measured and modeled dielectric responses, and integrating acoustic velocity measurements to reduce dependency on saturation levels and rock type assumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional methods use assumptions about saturation variation and constant formation pore structure, then the measurement process is simplified, but the accuracy of cementation and saturation exponent estimates deteriorates
Solution Approach 1:
The patent changes the measurement parameters by using multi-frequency dielectric measurements across a broad frequency spectrum (e.g., 1 MHz to 10 GHz) instead of single-frequency measurements. This parameter change allows extraction of multiple formation properties simultaneously, improving accuracy without requiring simplifying assumptions about saturation variation or pore structure constancy.
Solution Approach 2:
The patent adds the frequency dimension to dielectric measurements, transforming single-point measurements into multi-frequency spectral data. This dimensional expansion provides additional information about formation properties, enabling accurate determination of cementation and saturation exponents while accounting for variable saturation and pore structure without simplifying assumptions.
2Measurement precision
If multi-frequency dielectric data and acoustic velocity measurements are integrated, then the accuracy of formation property estimation is improved, but the device complexity increases
Solution Approach 1:
The patent merges dielectric measurement tools with acoustic velocity measurement tools into an integrated logging system. By combining these measurement capabilities in a single downhole tool assembly, the system achieves improved formation property estimation through multi-parameter data integration while minimizing the additional complexity that would result from separate tools requiring multiple runs.
Solution Approach 2:
The patent creates a universal logging tool that performs multiple functions: dielectric measurements at multiple frequencies, acoustic velocity measurements, and potentially other formation evaluation functions. This multi-functional approach consolidates what would otherwise require separate specialized tools, improving measurement accuracy while controlling overall system complexity through integration.
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 approach provides a more accurate and automated determination of cementation and saturation exponents, enhancing hydrocarbon recovery by improving the estimation of formation resistivity and water saturation relationships.
Implementation Method 1
applying a dielectric mixing model between different fluid phases to generate an effective fluid permittivity (εfluid) by mixing the permittivity of water and hydrocarbon fluids
Implementation Method 2
applying the dielectric mixing model between the effective fluid permittivity (εfluid) and a matrix permittivity (εm)
Implementation Method 3
acquiring the acoustic velocity measurements by transmitting and receiving elastic compressional or shear waves inside a formation
Data Source
AI summary
Examples described herein provide a computer-implemented method for deriving textural properties of a reservoir formation. The method includes acquiring multi-frequency dielectric data (εmeas). The method further includes applying a dielectric mixing model between different fluid phases to generate an effective fluid permittivity (εfluid) by mixing the permittivity of water and hydrocarbon fluids. The method further includes applying the dielectric mixing model between the effective fluid permittivity (εfluid) and a matrix permittivity (εm). The method further includes minimizing a difference between a measured dielectric response and the dielectric mixing model by optimizing model parameters. The method further includes computing a cementation exponent (m) and a saturation exponent (n) from the multi-frequency dielectric data (εmeas). The method further includes estimating a formation property based at least in part on the cementation exponent (m) and the saturation exponent (n). A wellbore operation is controlled based at least in part on the formation property.