Nuclear Density Tool Layer Segmentation
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Solution Overview
Problem
Current nuclear density tools are unable to accurately measure the density of individual annular layers within a wellbore, as they primarily provide bulk density measurements averaged over a depth, lacking the capability to resolve variations in density as a function of radial distance, and require knowledge of the borehole environment for correction.
Innovation Solution
A nuclear density tool employing a combination of radioactive gamma sources and multiple gamma detectors with an optimized source-to-detector configuration, utilizing Compton scattering to directly compute densities of individual layers, and incorporating a feedback mechanism to refine layer density measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a nuclear density tool measures bulk density averaged over depth, then the measurement covers the entire depth of investigation, but it cannot resolve density variations as a function of radial distance from the sensor
Solution Approach 1:
The patent divides the continuous radial measurement volume into discrete annular layers (first annular layer, second annular layer, etc.). Each layer's density is measured independently using specific detector combinations, transforming a single bulk measurement into multiple segmented measurements that preserve radial density variation information.
Solution Approach 2:
The patent transitions from measuring density in a single averaged dimension to measuring density across multiple radial dimensions. By using detectors at different positions and calculating densities for different annular layers, the system adds radial dimensionality to the measurement, enabling resolution of density variations with radial distance.
2Reliability
If current density tools use near and far detector contrast for borehole correction, then borehole environment effects are corrected, but knowledge of borehole size, standoff, and fluid composition is required
Solution Approach 1:
The patent enables the density tool to perform self-characterization by measuring densities of multiple annular layers and using this information to infer borehole properties. The system determines cement layer densities and borehole characteristics simultaneously without requiring external borehole environment data, making the tool self-sufficient.
Solution Approach 2:
The patent implements a feedback mechanism where the measured densities of intermediate annular layers are used to refine and improve the accuracy of the far detector density measurement. The near detector density, intermediate layer densities, and far detector density are calculated in a sequence where each measurement informs and corrects the others, creating a self-correcting measurement system.
3Measurement precision
If a nuclear density tool uses multiple gamma detectors with optimized source-to-detector configuration, then individual annular layer densities can be measured, but the device complexity increases
Solution Approach 1:
The patent segments the measurement function across multiple detectors, with each detector or detector combination responsible for measuring density in a specific annular layer. This segmentation enables precise individual layer measurements while distributing the complexity across multiple simpler detector units rather than requiring a single complex detector.
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 precise measurement of individual annular layer densities, improving accuracy and modality in both cased-hole and open-hole environments, including conditions with large or non-uniform standoffs, and shallow invasion, by enhancing spectral sensitivities and accounting for complex borehole geometries.
Implementation Method 1
utilizing Compton scattering to directly compute densities of individual layers
Data Source
AI summary
A method for determining a density may comprise disposing a nuclear density tool into a wellbore. The nuclear density tool may comprise a gamma source and a first gamma detector, wherein the first gamma detector and the gamma source are disposed on a longitudinal axis of the nuclear density tool. The method may further comprise transmitting an energy from the gamma source, detecting the energy reflected with the first gamma detector, recording a count rate of the energy at the first gamma detector, and identifying a density of a first layer from the count rate, a mass attenuation coefficient, and a source-to-detector distance. A system for determining a density may comprise a nuclear density tool. The nuclear density tool may comprise a gamma source configured to transmit an energy and a first gamma detector configured to detect reflected energy. The system may further comprise an information handling system.