PNC Logging Tool Proppant Detection Depth

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Solution Overview

Problem

Current methods for detecting induced subterranean fractures and frac-pack or gravel-pack material in hydraulic fracturing operations are limited by logistical challenges, mechanical issues, and safety concerns, including the need for radioactive materials, complex equipment, and shallow depth of investigation.

Innovation Solution

The use of pulsed neutron capture (PNC) logging tools with proppants doped with thermal neutron absorbing materials like boron or gadolinium, which are pumped downhole and detected post-fracturing to determine the location and height of fractures and pack material distribution using pre- and post-fracture data sets, allowing for differentiation between proppant in the borehole and formation fractures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If radioactive materials and complex gamma ray spectroscopy equipment are used to detect fractures and pack material, then detection capability is improved, but logistical complexity and safety hazards increase

Engineering Contradiction:

Improvedetection capabilityVSAvoidlogistical complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex gamma ray spectroscopy equipment and radioactive materials with a pulsed neutron capture (PNC) logging tool that uses neutron sources and detectors. This substitution eliminates the need for radioactive materials while maintaining detection capability for identifying fractures and pack material through neutron capture reactions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The PNC logging tool uses temporary neutron sources that are activated during the logging operation and then deactivated, eliminating the need for long-lived radioactive materials. The neutron sources are consumed during the measurement process, providing a safe and logistically simple alternative to permanent radioactive tracers.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If radioactive materials are used to trace proppant location, then measurement precision is improved, but safety hazards and regulatory complexity increase

Engineering Contradiction:

Improveproppant location detectionVSAvoidsafety hazards

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes radioactive tracer materials with a pulsed neutron capture logging tool that detects proppant location through neutron capture reactions. This replacement eliminates radiation safety hazards while maintaining the ability to precisely locate proppant in fractures and pack zones.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent converts the potential harm of radioactive materials into a beneficial detection mechanism by using neutron capture reactions. The neutron capture process, which would otherwise be a background phenomenon, is enhanced by the presence of proppant materials containing certain elements, creating a detectable signal without radiation hazards.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If shallow depth of investigation methods are used, then equipment complexity is reduced, but fracture detection capability at depth is limited

Engineering Contradiction:

Improveequipment simplicityVSAvoiddepth of investigation

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The PNC logging tool uses periodic pulsed neutron sources that are activated in intervals during the logging operation. This periodic activation allows the tool to achieve deep penetration and detection capability by accumulating signal strength over multiple pulses, while keeping the equipment relatively simple compared to continuous radioactive tracer methods.

Inventive Principle:

Principle #19Periodic 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 method provides deeper investigation capabilities, reduces logistical and safety hazards, and is cost-effective, enabling accurate identification of fractured and packed zones without the need for complex gamma ray spectroscopy or radioactive materials, thus improving the efficiency and safety of hydraulic fracturing operations.

Implementation Method 1

a pulsed neutron capture (PNC) logging tool... detecting thermal neutrons or capture gamma rays resulting from nuclear reactions of the source neutrons with elements in the borehole region and formation

Methodology Applied

Scientific EffectNeutron capture: Absorption (physical)

Implementation Method 2

proppants doped with thermal neutron absorbing materials like boron or gadolinium, which are pumped downhole and detected post-fracturing

Methodology Applied

Scientific EffectThermal neutron absorption: Absorption (physical)

Data Source

PatentUS9038715B2Use of PNC tools to determine the depth and relative location of proppant in fractures and the near borehole region

Publication Date: 2015.05.26 CARBO CERAMICS INC

AI summary

Methods are provided for identifying the location and height of induced subterranean formation fractures and the presence of any associated frac-pack or gravel pack material in the vicinity of the borehole using pulsed neutron capture (PNC) logging tools. The proppant/sand used in the fracturing and packing processes is tagged with a thermal neutron absorbing material. When proppant is present, increases in detected PNC formation and/or borehole component cross-sections, combined with decreases in measured count rates, are used to determine the location of the formation fractures and the presence and percent fill of pack material in the borehole region. Changes in measured formation cross-sections relative to changes in other PNC parameters provide a relative indication of the proppant in fractures compared to that in the borehole region.