Pulsed Neutron Logging Calibration Using Oxide Reference Spectra
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Solution Overview
Problem
Current pulsed-neutron logging tools face challenges in accurately quantifying elemental concentrations due to the complexity of lithology and limitations in data processing methods, particularly when using pure elemental standards that provide an unnatural representation of the chemical composition of rock formations.
Innovation Solution
Utilizing oxide standards as reference materials for pulsed-neutron logging tools to enhance the accuracy of mineralogy analysis by employing weighted-least-square fitting algorithms, which provide a more natural and realistic representation of geological formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pure elemental standards are used for calibration, then the calibration process is simplified, but the accuracy of elemental quantification deteriorates due to unnatural representation of chemical composition
Solution Approach 1:
The patent changes the chemical composition parameter of the calibration standards from pure elements to oxide compounds. This parameter change transforms the calibration approach to better represent natural rock formations, thereby improving measurement precision while maintaining calibration process simplicity through the use of well-defined oxide compounds.
Solution Approach 2:
The patent employs composite oxide compounds (such as SiO2, CaO, Fe2O3, MgO, Al2O3, K2O, Na2O, TiO2, MnO, P2O5, CO2, SO3) as calibration standards instead of pure elements. These composite oxide materials better represent the actual chemical composition of rock formations, improving the accuracy of elemental quantification while providing a systematic calibration approach.
2Ease of operation
If reference spectra of pure elements are employed in weighted-least-square fitting, then the fitting algorithm is straightforward, but the quantification of elemental concentrations and mineralogy distribution becomes less accurate
Solution Approach 1:
The patent changes the reference material parameter from pure elements to oxide compounds in the weighted-least-square fitting algorithm. This parameter change improves mineralogy analysis accuracy by better representing natural rock compositions, while the algorithm remains straightforward by following the same fitting procedure with updated reference spectra.
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
Improves the precision and reliability of elemental quantification and mineralogy analysis by accounting for the complex mineralogical and lithological heterogeneity of real-world rock formations, leading to enhanced reservoir characterization.
Implementation Method 1
A pulsed neutron logging tool emits neutrons to interact with nuclei of any material to induce gamma radiation
Implementation Method 2
The excited target nucleus relaxes to its ground state by emitting characteristic gamma radiation
Implementation Method 3
In elastic neutron-scattering, the neutron bounces off the bombarded nucleus without exciting it or destabilizing it. With each elastic interaction, the neutron loses energy
Implementation Method 4
In neutron absorption, the nucleus absorbs the neutron and becomes excited, typically emitting captured gamma rays
Data Source
AI summary
The techniques as described herein enhance the accuracy and precision of mineralogy analysis in elemental spectroscopy logging by utilizing oxide standards and/or rock-forming mineral compounds as reference materials that provide more representative and realistic signatures of geological formations. A method comprises logging a wellbore with a tool and fitting reference spectra from oxide compounds and/or rock-forming mineral compounds against measured gamma spectra obtained with the tool, to characterize a subterranean formation that the wellbore extends through.