Pulsed Neutron Source Formation Characterization

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Solution Overview

Problem

Current methods for determining geological formation characteristics, such as density and porosity, face challenges including safety hazards from chemical neutron sources, logistical complications, and inaccuracies due to dependencies on neutron generator output and calibration, as well as neglecting neutron and gamma transport effects.

Innovation Solution

Employing a non-chemical neutron accelerator source and accounting for neutron and gamma transport effects, the method uses pulsed neutron techniques with gamma-ray detectors to measure formation characteristics independently of neutron generation rate, considering various factors like hydrogen content, rock type, and density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If chemical (radioisotope) sources of neutrons are used, then neutron generation is readily available, but safety hazards and logistical complications arise

Engineering Contradiction:

Improveneutron generation availabilityVSAvoidsafety hazards

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent replaces chemical (radioisotope) neutron sources with a physical/electronic neutron generator system that uses electrical acceleration of ions to produce neutrons through nuclear reactions. This substitution eliminates the safety hazards and logistical complications associated with chemical sources while maintaining neutron generation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If methods depend on accurate knowledge of neutron generator output and calibration, then measurement can be performed, but measurement precision deteriorates due to dependencies and calibration requirements

Engineering Contradiction:

Improvemeasurement capabilityVSAvoidformation characteristic determination accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent incorporates feedback mechanisms where the actual neutron output is measured and used to adjust and normalize the formation characteristic calculations. This feedback loop compensates for variations in neutron generator output and eliminates the need for precise prior knowledge of neutron output, thereby improving measurement precision.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the measurement parameters from absolute neutron output dependence to ratio-based measurements that are insensitive to neutron generator output variations. By using ratios of gamma ray counts at different energy levels or time intervals, the method eliminates the need for calibration and improves precision.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If neutron and gamma transport effects are neglected, then measurement process is simplified, but measurement precision deteriorates due to unaccounted variables

Engineering Contradiction:

Improvemeasurement process complexityVSAvoidgamma flux measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary corrections for neutron and gamma transport effects by incorporating known transport parameters and formation characteristics into the measurement model before data analysis. This preliminary action accounts for attenuation and scattering effects, improving measurement precision without significantly increasing operational complexity.

Inventive Principle:

Principle #10Preliminary action

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 provides more accurate determination of formation characteristics like density and porosity, reducing reliance on chemical sources and improving measurement precision by accounting for multiple variables affecting gamma flux.

Implementation Method 1

a source 84 may comprise a neutron generator, such as a pulsed neutron generator

Methodology Applied

Scientific EffectNeutron generation via acceleration: Electrostatic Induction

Implementation Method 2

the package 80 may comprise a plurality of gamma ray detectors 86

Methodology Applied

Scientific EffectGamma ray detection: Photoelectric Effect

Data Source

PatentUS8847149B2Determining formation characteristics

Publication Date: 2014.09.30 HALLIBURTON ENERGY SERVICES INC

AI summary

In some embodiments, apparatus and systems, as well as methods, may operate to irradiate a portion of a geological formation with neutrons in a neutron burst generated by a switchable electronic source, to measure (with one or more detectors) a flux of gamma rays to provide a measured flux, at least a portion of the gamma rays being generated by the neutrons, and to determine one or more of a neutron porosity, a density, and/or a photoelectric factor of the geological formation based on the measured flux. Other apparatus, systems, and methods are disclosed.