Drilling Cuttings Permittivity Analysis via Zero-Contrast Matching
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Solution Overview
Problem
Current methods for determining the permittivity of drilling cuttings, essential for reservoir characterization, face challenges in accurately measuring the rock's dielectric constant and irreducible water saturation, which are crucial for reliable estimation of reservoir properties like water saturation and cementation factor.
Innovation Solution
A method involving the analysis of drilling rock cuttings by comparing their permittivity to known liquid mixtures, using zero-contrast measurements and the CRIM law, to determine the rock's dielectric constant and porosity, while accounting for changes in temperature and pressure during drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If wire line tools are used to measure complex permittivity, then information on water saturation and cementation factor can be obtained, but accurate determination of rock dielectric constant requires independent measurements
Solution Approach 1:
The patent applies preliminary action by measuring the dielectric constant of rock cuttings before they are used in wire line tool interpretation. The method involves collecting cuttings, drying them, and performing dielectric measurements on the dried material to obtain the rock dielectric constant value that will be used as input for subsequent reservoir property calculations. This preliminary measurement ensures accurate interpretation of the wire line tool data.
2Reliability
If mixing laws are used to interpret complex permittivity measurements, then reservoir properties can be estimated, but accurate input parameters are required for reliable estimation
Solution Approach 1:
The patent replaces the need for direct in-situ measurement of rock dielectric constant with an alternative approach using rock cuttings. Instead of measuring the dielectric constant directly in the formation, the method uses laboratory measurements on dried cuttings to obtain the rock dielectric constant. This substitution provides a reliable and repeatable measurement method that ensures accurate input parameters for the mixing law interpretation.
3Measurement precision
If rock cuttings are used for dielectric measurement, then matrix dielectric constant can be determined, but measurement of irreducible water saturation is also required
Solution Approach 1:
The patent applies segmentation by separating the measurement of rock dielectric constant and irreducible water saturation as distinct but complementary measurements. The dielectric constant is measured on dried cuttings to remove the influence of water, while the irreducible water saturation is measured separately using other methods. Both measurements are then combined to provide complete input parameters for the mixing law interpretation, ensuring both rock and fluid properties are accurately characterized.
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 allows for precise determination of rock permittivity and irreducible water saturation, enhancing the interpretation of dielectric measurements and improving the accuracy of reservoir property estimation.
Implementation Method 1
Complex permittivity measurements can provide information on the water saturation and the cementation factor of the rock formation in the vicinity of the borehole. Complex permittivity can be obtained from measurements made using wire line tools.
Data Source
AI summary
Systems and methods for analysis of drilling cuttings are described. Complex permittivity is measured of rock cutting samples obtained during drilling operations. The origin of the cuttings is known by flow rate analysis in the drilling system. Various means can be used for rock cutting dielectric measurement. For example, the dielectric measurement can be made by matching the unknown permittivity of the medium to be analyzed to the permittivity of known liquid mixtures by successive saturation and looking for a “zero-contrast” measurement.