Rock Gas Diffusion Sampling Chamber for Pressure-Stable Measurement
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Solution Overview
Problem
Current methods for determining gas diffusion coefficient in rocks suffer from pressure disturbances during sampling, leading to poor repeatability and increased errors due to sudden changes in pressure difference between diffusion chambers.
Innovation Solution
A device and method that utilize a core holder with sampling mechanisms featuring a first blind tube and a second blind tube with rotating sealing strips to isolate sampling cavities from the diffusion chamber, allowing undisturbed gas sampling without affecting chamber pressure, combined with a gas analyzer and pressure gauge for accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas sampling is performed by extracting gas from the diffusion chamber, then gas composition can be detected, but the pressure in the diffusion chamber is disturbed causing sudden changes in pressure difference and abnormal fluctuations in diffusion rate
Solution Approach 1:
The system is divided into three distinct chambers: diffusion chamber, sampling chamber, and detection chamber. The sampling mechanism includes a sampling piston that can isolate the sampling chamber from the diffusion chamber, allowing gas to be transferred and analyzed without removing gas from the diffusion chamber, thus preventing pressure disturbances
Solution Approach 2:
The sampling chamber acts as an intermediary between the diffusion chamber and the detection chamber. Gas is transferred from the diffusion chamber to the sampling chamber through a communication hole, then analyzed in the detection chamber, allowing composition detection without direct extraction from the diffusion chamber
2Loss of time
If multiple samplings are performed during the test process, then more data points can be obtained, but each sampling extracts gas from the diffusion chamber causing pressure disturbance and increasing errors
Solution Approach 1:
The sampling chamber is segmented from the diffusion chamber with a movable sampling piston, enabling multiple sampling operations to be performed sequentially without affecting the diffusion chamber pressure, thus maintaining measurement precision over extended testing periods
Solution Approach 2:
Gas is pre-transferred from the diffusion chamber to the sampling chamber before analysis, allowing multiple analyses to be performed on the stored gas sample without repeated disturbances to the diffusion chamber, thereby maintaining pressure stability throughout the testing process
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
The solution ensures undisturbed sampling, reducing pressure interference and improving the accuracy of gas diffusion coefficient measurements by maintaining consistent chamber pressure during the sampling process.
Implementation Method 1
the second blind tube has a closed end facing the diffusion chamber and an open end in rotary sealing connection with the cylinder
Implementation Method 2
The determination of gas diffusion coefficient in rocks is currently predominately performed using unsteady-state methods... causing abnormal fluctuations in the diffusion rate of gas molecules
Data Source
AI summary
Disclosed are a device and method for determining gas diffusion coefficient in rocks. The device includes: a core holder, a sampling mechanism, a gas analyzer, a gas source and a pressure gauge. A middle part of the core holder holds a rock sample, two sampling mechanisms are symmetrically arranged at two ends of the rock sample, each sampling mechanism includes a first blind tube, a cylinder, a second blind tube and a sampling cavity, an open end of the first blind tube faces the rock sample and is in sealing connection with an end surface of the rock sample to form a diffusion chamber. A single sampling cavity is isolated from the diffusion chamber, and the pressure of the diffusion chamber is not affected, so that undisturbed sampling is achieved, the influence on the pressure of the diffusion chamber is reduced, and the accuracy of the determination results is improved.