Thermal Modulated Vibrating Gas Sensor for Downhole Molecular Weight

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Solution Overview

Problem

Current methods for measuring gas molecular weight in wellbore formation fluids are limited by the need for offline laboratory analysis and inability to operate effectively under high temperature and pressure downhole conditions, leading to inaccuracies in gas phase flowrate measurement due to varying densities of hydrocarbon mixtures.

Innovation Solution

A thermal modulated vibrating sensing module with paired gas sensors operating at different temperatures, using vibrational measurements and differential pressure to determine gas molecular weight in-situ, allowing for real-time analysis of hydrocarbon gas composition and reservoir properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional offline gas chromatography analysis is used to determine gas molecular weight, then measurement accuracy is improved, but loss of time increases and adaptability to downhole conditions deteriorates

Engineering Contradiction:

Improvegas molecular weight measurement accuracyVSAvoidanalysis time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical/chemical separation system of gas chromatography with a thermal modulated vibrating tube sensing system that measures gas density directly through vibrational frequency changes, enabling real-time molecular weight determination without offline analysis

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the measurement parameter from retention time analysis in chromatography to vibrational frequency of a heated tube, which is directly influenced by gas density and molecular weight, allowing immediate in-situ measurement

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If conventional gas sensors operate under high temperature and pressure downhole conditions, then adaptability to downhole environment is improved, but measurement precision deteriorates due to varying gas densities

Engineering Contradiction:

Improvedownhole condition operation capabilityVSAvoidgas molecular weight measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent introduces thermal modulation as a controlling parameter, where the tube temperature is modulated at a specific frequency to create density oscillations that enhance the vibrational signal, allowing precise measurements despite high temperature and pressure variations

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The sensing system employs periodic thermal modulation of the vibrating tube, where the tube temperature is varied sinusoidally to create periodic density changes in the gas, which amplifies the vibrational frequency shifts and improves measurement precision under downhole conditions

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If paired gas sensors operating at different temperatures are used, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvegas molecular weight determination accuracyVSAvoidsensing module structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines two gas sensors into a single integrated sensing module with a common structure, where both sensors share the same mechanical support, electrical connections, and processing circuitry, reducing overall device complexity while maintaining measurement precision

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sensing module is segmented into functionally independent sensor units that can be manufactured and calibrated separately, then assembled into a complete module, simplifying the manufacturing and maintenance process while achieving precise differential measurements

Inventive Principle:

Principle #1Segmentation

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

Enables accurate, real-time measurement of gas molecular weight and composition, improving the accuracy of gas phase flowrate measurement and providing immediate analysis of hydrocarbon gas composition, reducing the need for conventional offline chromatography and enhancing downhole sampling tool capabilities.

Implementation Method 1

the resonant frequency of the heated tube varies with the density of the gas

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

thermal modulated vibrating sensing module

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10921476B2Thermal modulated vibrating sensing module for gas molecular weight detection

Publication Date: 2021.02.16 HALLIBURTON ENERGY SERVICES INC

AI summary

A downhole formation fluid identification sensing module for measuring averaged gas molecular weight of wellbore formation fluid acquires simultaneous temperature, pressure, and density measurements. The sensing module includes two venturi-type gas sensors that both contain vibrating tubes. During operation, formation fluid flows through the vibrating tubes whereby resonant frequency measurements are acquired simultaneously with temperature and pressure measurements. Each measurement is then utilized to determine the gas molecular weight of the dry, wet or saturated formation fluid.