GB/T 35210.2-2020 in English
VALIDDetermination methods of methane isothermal adsorption of shale—Part 2:Gravimetric method
- Issued on:2020-12-14
- Implemented on:2021-07-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
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《GB/T 35210.2-2020页岩甲烷等温吸附测定方法 第2部分：重量法》由TC244（全国天然气标准化技术委员会）归口，主管部门为国家标准化管理委员会。
Introduction
Analysis of the core content of the standard
GB/T35210.2-2020 stipulates the gravimetric method for determining the adsorption performance of shale methane using a magnetic suspension balance. The technical highlights include:
- Pressure requirements: balance accuracy ≥0.01mg, temperature control ±0.1℃
- Pressure range: test upper limit 60MPa, the pressure point of the adsorption test is set according to the principle of dense first and sparse later
- Sample specifications: particle size 0.180-0.425mm, mass ≥20g
Comparison of key instrument configurations
| System components | Technical requirements | Comparison of Volumetric Method |
|---|---|---|
| Magnetic Suspension Balance | Accuracy 0.01mg | Not applicable |
| High Pressure Chamber | ≥60MPa | Same |
| Temperature Control | ±0.1℃ | Same |
| Gas Medium | CH4/He/N2 | CH4 Only |
Key Points of Test Process
1. Pretreatment stage
Vacuum degree <1kPa, temperature setting follows:
When adsorption temperature ≤100℃: 105-110℃
When adsorption temperature >100℃: 5-10℃ higher than adsorption temperature
2. Buoyancy test
Use helium to set ≥6 pressure points in the range of 0-6MPa, equilibrium conditions:
Temperature fluctuation ≤0.2℃ and mass change of <50μg in 10min
3. Adsorption test
Pressure point setting rules:
≤30MPa interval ≤2MPa
>30MPa interval ≤5MPa
Key points of data processing technology
Adsorption calculation model
Ternary Langmuir equation is used:
Vex = (VL·P)/(PL+P)·(1-ρg/ρa)
where ρa needs to be determined by nonlinear fitting
Quality verification requirements
Allowable error of repeated tests:
Relative error of Langmuir volume VL and Langmuir pressure PL≤10%
Recommendations for the implementation of standards
Operation precautions
- Oil-containing samples need to be washed with oil according to GB/T29172
- The airtightness check requires the pressure drop to be maintained at ≤0.5MPa for 10 minutes
- It is recommended to use the NIST database to obtain accurate gas density
Technical development background
The advantages of this standard over the volumetric method:
- Directly measure the change in adsorption mass
- Obtain adsorption phase density parameters
- Applicable to high temperature and high pressure conditions
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