Formation Evaluation Using Permittivity and Gamma Ray Separation
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Solution Overview
Problem
Existing gamma ray logging tools struggle to distinguish between clay-free or low-clay formations and shale formations due to non-uniqueness in GR flux measurements, leading to potential misidentification of hydrocarbon reserves.
Innovation Solution
Utilizing electromagnetic measurement data to determine permittivity, which is used to calculate total gamma ray flux and identify clay types and volumes, combined with GR measurements to classify formation rock as clean, clay-free, or low-clay with common elemental components, employing correlation models based on permittivity data at predefined frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If total gamma ray flux measurements are used to distinguish between shales and non-shales, then the ability to identify formation types is improved, but measurement precision deteriorates due to non-uniqueness interpretation
Solution Approach 1:
The patent segments the total gamma ray flux measurement into multiple energy bins, analyzing gamma rays at different energy levels (e.g., potassium peak, thorium peak, uranium peak) separately. This segmentation allows differentiation between clay-related gamma rays and elemental component gamma rays, resolving the non-uniqueness problem in formation identification.
Solution Approach 2:
The patent changes the measurement parameter from total gamma ray flux to energy-resolved gamma ray spectra. By measuring gamma ray intensity at specific energy levels corresponding to different radioactive elements, the system can distinguish between clays and elemental components with similar total gamma ray signatures, improving measurement precision.
2Measurement precision
If spectral gamma ray logging tools are used to analyze gamma rays into energy bins, then determination of elemental concentrations is improved, but device complexity increases
Solution Approach 1:
The patent employs a universal detection system that can perform both total gamma ray flux measurement and energy-resolved spectral analysis using the same basic detector hardware. This multi-functionality allows the system to determine elemental concentrations without requiring separate specialized devices for each measurement type.
Solution Approach 2:
The patent uses computational models to create simplified representations of complex gamma ray interactions. By modeling the expected gamma ray spectra for different formation types and comparing measured spectra to these models, the system achieves accurate elemental concentration determination without requiring overly complex physical detection systems.
3Reliability
If multiple logging tools are used together to refine interpretation, then formation evaluation accuracy is improved, but device complexity and operational complexity increase
Solution Approach 1:
The patent merges the functionality of multiple logging tools into a single integrated system. By combining gamma ray detection, electromagnetic measurement, and formation evaluation capabilities in one tool, the system achieves comprehensive formation evaluation without requiring separate tools for each measurement type, reducing overall system complexity.
Solution Approach 2:
The patent introduces computational modeling and data processing algorithms as intermediaries between raw measurements and formation interpretation. These intermediaries integrate data from multiple measurement types and apply physical models to derive formation properties, reducing the need for direct complex interactions between multiple physical tools.
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
Accurately differentiates between high GR flux formations with and without clay, preventing misidentification of hydrocarbon reserves and improving formation evaluation.
Implementation Method 1
collecting or obtaining electromagnetic measurement data that results from interaction of electrical signals with a sample of the formation
Implementation Method 2
The data representing permittivity of the sample of the formation at a predefined low frequency (e.g., 1 MHz and below) can be supplied as input to at least one correlation model
Implementation Method 3
The data representing total gamma ray flux for the at least one clay type contained in the sample of the formation can be obtained through nuclear particles modeling
Data Source
AI summary
The disclosure relates to methods and systems for identifying formations that are clay-free or with minimal amount of clays, which have high hydrocarbon potential, by using both low frequency permittivity measurements (e.g., low-frequency permittivity measurements) and natural gamma ray flux measurements.