Azimuthal Elemental Imaging in Borehole Logging
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Solution Overview
Problem
Current geological exploration methods in wellbores provide limited information about the mineral composition of earth formations, despite offering structural data, which hinders complete lithologic characterization.
Innovation Solution
An apparatus and method utilizing a radiation detector and processor to estimate the elemental composition of earth formations by making measurements of natural gamma rays and associating them with azimuths, allowing for elemental composition estimation, and incorporating a pulsed neutron source and detectors to analyze gamma ray spectra for elemental and mineralogical data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional imaging methods (electrical, acoustic, gamma ray, density measurements) are used to produce borehole wall images, then structural information about the earth formation is revealed, but information about formation mineral composition is provided little or no information
Solution Approach 1:
The patent combines multiple measurement capabilities (natural gamma ray detection, pulsed neutron source, and spectral analysis) into a single logging tool assembly. This merging of functions allows the tool to simultaneously obtain structural information and mineral composition data, resolving the contradiction by integrating previously separate measurement systems into one comprehensive device that delivers both structural and compositional information without requiring multiple separate tools
Solution Approach 2:
The logging tool is designed with multi-functionality, serving both as a structural imager and a mineralogical analyzer. By incorporating natural gamma ray detectors with azimuthal sensitivity and pulsed neutron spectroscopy capabilities, the single tool performs multiple functions: obtaining borehole wall images, measuring formation density, and determining elemental composition. This universal design eliminates the need for separate specialized tools while providing comprehensive formation characterization
2Loss of information
If separate wireline logging runs are performed after drilling to obtain complete formation evaluation data, then comprehensive formation parameters (resistivity, porosity, permeability, mineral composition) are obtained, but time and cost increase
Solution Approach 1:
The patent enables preliminary acquisition of complete formation evaluation data during the drilling operation itself, before the formation is damaged by mud invasion. By integrating mineralogical analysis capabilities into the drilling tool assembly, the system performs formation evaluation measurements in advance, obtaining both structural and compositional data while the formation is undisturbed. This preliminary action eliminates the need for subsequent wireline logging runs, saving time and preserving formation integrity
Solution Approach 2:
The patent merges drilling operations with formation evaluation logging into a single simultaneous process. The logging tool assembly travels with the drill string, allowing measurement-while-drilling (MWD) and logging-while-drilling (LWD) operations. This combination enables acquisition of complete formation parameters (resistivity, porosity, permeability, and mineral composition) during drilling, eliminating the need for separate post-drilling wireline logging runs and reducing total evaluation time
3Measurement precision
If formation measurements are taken after wellbores are drilled using conventional logging, then formation parameters are obtained, but the formation may already be damaged by drilling mud invasion reducing data quality
Solution Approach 1:
The patent performs formation evaluation measurements in advance, during the drilling operation itself, before the formation undergoes damage from mud invasion. By conducting logging-while-drilling (LWD) measurements, the system captures formation parameters (resistivity, porosity, permeability, and mineral composition) while the formation is still in its undisturbed state. This preliminary measurement action ensures high data quality by avoiding post-drilling formation degradation, eliminating the time delay between drilling completion and measurement
4Loss of information
If azimuthal sensitivity is incorporated into natural gamma ray detection, then elemental composition can be estimated for multiple azimuths enabling complete lithologic characterization, but device complexity increases
Solution Approach 1:
The patent segments the gamma ray detection system into multiple discrete detector elements arranged in an azimuthal pattern around the tool axis. Each detector element independently measures gamma ray intensity from a specific azimuthal direction. This segmentation of the detection system enables reconstruction of three-dimensional gamma ray emission patterns, allowing estimation of elemental composition for multiple azimuths and complete lithologic characterization while maintaining manageable device complexity through modular detector architecture
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 more complete lithologic characterization of earth formations during drilling, providing valuable information for reservoir navigation and hydrocarbon recovery by improving the accuracy of mineral composition analysis and reducing the need for separate wireline logging.
Implementation Method 1
at least one radiation detector configured to be conveyed in a borehole and make a plurality of first measurements of natural gamma rays
Implementation Method 2
incorporating a pulsed neutron source and detectors to analyze gamma ray spectra
Data Source
AI summary
Measurements made by a natural gamma ray tool are used to provide an elemental composition of an earth formation. Additional measurements made with a pulsed neutron tool with two or more gamma ray detectors are used to provide a mineralogical and/or elemental image of the formation. This may be used in reservoir navigation and in furthering the understanding of the geology of the prospect.