Pulsed Neutron Logging Multivariate Inversion via Database Lookup

Solution Overview

Problem

Pulsed-neutron logging tools face challenges in simultaneously determining multiple petrophysical properties due to complex fast neutron interactions in borehole environments, requiring extensive processing time and computational energy, which increases costs.

Innovation Solution

Implementing a tool-data-centric multivariate inversion method that iteratively solves for multiple borehole conditions without the need for physics-based algorithms by comparing PNL measurements to a database populated with simulated data using a cost function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If physics-based algorithms are used to isolate and correlate petrophysical properties with PNL measurements, then measurement precision is improved, but processing time and computational energy increase

Engineering Contradiction:

Improvepetrophysical properties determination accuracyVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent pre-calculates and stores response functions for various borehole conditions in a lookup table before actual logging operations. During field operations, the system simply queries this pre-computed database rather than performing complex real-time calculations, thereby eliminating lengthy processing delays while maintaining accurate inversion results for multiple petrophysical properties

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a simplified computational model that replicates the essential physics of neutron interactions without requiring full complex simulations. By using pre-computed response functions that capture the key relationships between borehole conditions and PNL measurements, the system achieves accurate property determination with minimal computational overhead during actual processing

Inventive Principle:

Principle #26Copying

2Measurement precision

If physics-based algorithms are used to isolate and correlate petrophysical properties with PNL measurements, then measurement precision is improved, but computational energy increases

Engineering Contradiction:

Improvepetrophysical properties determination accuracyVSAvoidcomputational energy

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent pre-calculates and stores response functions for various borehole conditions in a lookup table before actual logging operations. During field operations, the system simply queries this pre-computed database rather than performing complex real-time calculations, thereby eliminating lengthy processing delays while maintaining accurate inversion results for multiple petrophysical properties

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a simplified computational model that replicates the essential physics of neutron interactions without requiring full complex simulations. By using pre-computed response functions that capture the key relationships between borehole conditions and PNL measurements, the system achieves accurate property determination with minimal computational overhead during actual processing

Inventive Principle:

Principle #26Copying

3Device complexity

If traditional methods isolate and correlate one or two petrophysical properties with PNL measurements, then device complexity is reduced, but adaptability decreases

Engineering Contradiction:

Improvealgorithm complexityVSAvoidnumber of petrophysical properties determined

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent develops a unified inversion framework that simultaneously determines multiple petrophysical properties (formation porosity, fluid saturation, lithology, borehole parameters) using a single integrated algorithm. The system uses a comprehensive response function that accounts for interactions among all these properties, allowing one tool to perform multiple measurement functions without requiring separate specialized algorithms for each property type

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 the simultaneous identification of multiple petrophysical properties in real-time, reducing processing time and computational energy, and improving accuracy without the need for physics-based algorithm development.

Implementation Method 1

A PNL tool may operate and function by utilizing nuclear detectors to measure induced gammas by interaction of high energy neutrons that are emitted from a generator

Methodology Applied

Scientific EffectNeutron interaction:

Implementation Method 2

Induced gamma measurements may include inelastic spectrum and capture spectrum

Methodology Applied

Scientific EffectGamma ray emission:

Data Source

PatentUS12135402B2Algorithm-free, data-centric multivariate inversion for pulsed neutron logging

Publication Date: 2024.11.05 HALLIBURTON ENERGY SERVICES INC

AI summary

A method and system for identifying one or more petrophysical properties in a formation. The method and system may include disposing a pulsed-neutron logging tool into a borehole that is disposed in a formation, emitting a neutron from a neutron source on the pulsed-neutron logging tool into the formation, and capturing one or more gammas expelled from formation in response to the neutron from the neutron source to form a plurality of pulsed neutron logging (PNL) measurements in a log. The method and system may further include comparing the log to a database with a cost function to form a solution; and identifying a plurality of petrophysical properties based at least in part on the solution.