Gamma Logging Detector Assembly with Low-Density Pressure Sleeve

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Solution Overview

Problem

Natural gamma radiation logging during logging while drilling (LWD) is sensitive to material composition and configuration of BHA components, which attenuate incoming gamma radiation, and mechanical disturbances like shock and vibration distort spectral gamma measurements, leading to low count intensity.

Innovation Solution

A detector assembly with a support structure comprising cylindrical segments and an annular pressure sleeve made of low-density, low-atomic-number materials like Ti-6AL-2SN-4ZR-6MO alloy, which minimizes gamma attenuation and provides mechanical toughness to withstand downhole pressures, allowing increased gamma ray counts and flexibility to relieve bending stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If BHA components are made of high-density materials to provide structural strength, then mechanical strength is improved, but gamma radiation attenuation increases

Engineering Contradiction:

Improvemechanical strengthVSAvoidgamma radiation attenuation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by using different materials for different components: high-density materials (steel, nickel) for structural elements requiring strength, and low-density materials (titanium, aluminum) for components near the gamma detector. This spatial differentiation of material properties optimizes both mechanical strength and gamma transmission locally where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite material strategies by combining high-density and low-density materials within the same BHA assembly. The detector assembly includes a support structure with high-density materials for structural integrity and low-density materials for gamma transmission, creating a composite structure that simultaneously satisfies both contradictory requirements.

Inventive Principle:

Principle #40Composite materials

2Strength

If the detector assembly is made more flexible to relieve bending stresses, then mechanical stress resistance is improved, but structural stability deteriorates

Engineering Contradiction:

Improvestress resistanceVSAvoidstructural stability

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by providing flexibility only in specific regions where bending stresses occur, while maintaining rigidity in other areas. The support structure includes flexible elements at strategic locations to accommodate bending without compromising overall structural stability or detector positioning.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the mechanical parameters of the support structure by incorporating materials and design features that modify rigidity and flexibility characteristics. This allows the structure to adapt its mechanical properties to withstand bending stresses while maintaining sufficient stability for accurate gamma measurement.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If low-density materials are used to reduce gamma attenuation, then gamma ray count intensity is improved, but mechanical strength deteriorates

Engineering Contradiction:

Improvegamma ray count intensityVSAvoidmechanical strength

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent applies local quality by using low-density materials specifically for components where gamma transmission is critical (such as the pressure sleeve and detector support), while reserving high-density materials for structural elements requiring high strength. This localized material selection optimizes gamma transmission without sacrificing overall mechanical strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Inventive Principle:

Principle #40Composite materials

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

Enhances measured gamma ray counts and improves the accuracy of spectral gamma radiation logging by reducing attenuation and mechanical stress on logging tool components, enabling better borehole imaging and directional drilling.

Implementation Method 1

low density, low effective atomic number material presents a reduced gamma attenuation barrier

Methodology Applied

Scientific EffectGamma radiation attenuation: Absorption (EM radiation)

Implementation Method 2

naturally occurring gamma radiation is measured by scintillation detectors deployed in a BHA

Methodology Applied

Scientific EffectScintillation detection: Scintillation

Implementation Method 3

flexibility to relieve bending stresses

Methodology Applied

Scientific EffectFlexure: Elasticity

Data Source

PatentUS11169300B1Gamma logging tool assembly

Publication Date: 2021.11.09 HALLIBURTON ENERGY SERVICES INC

AI summary

Disclosed embodiments include a gamma logging detector assembly that includes a detector support structure comprising one or more high density alloy materials and including a first cylindrical drill collar segment and a second cylindrical drill collar segment each having a radius of at least R1. A third cylindrical drill collar segment is disposed axially between the first and second cylindrical drill collar segments to form an annular channel over the third cylindrical drill collar segment and between the first and second cylindrical drill collar segments. The third cylindrical drill collar segment includes an inwardly defined open cavity and a radius, R2, that is less than R1. An annular pressure sleeve comprising one or more low density alloy materials is disposed within the annular channel.