"Multi-temperature" method for high-pressure sorption measurements on moist shales

Area of Science:

• Geochemistry
• Materials Science
• Physical Chemistry

Background:

• Accurate measurement of gas sorption in shales is crucial for understanding natural gas storage and CO2 sequestration.
• Previous methods for studying temperature dependence of sorption were time-consuming and complex.
• Moisture content significantly impacts gas sorption behavior in porous materials like shale.

Purpose of the Study:

• To develop and validate a novel experimental approach for studying the temperature dependence of high-pressure methane sorption in moist organic-rich shales.
• To enable simultaneous measurement of multiple sorption isotherms at different temperatures in a single experimental run.
• To obtain reliable thermodynamic sorption parameters, considering the influence of water vapor.

Main Methods:

• Development of a "multi-temperature" (multi-T) experimental method for sorption studies.
• Conducting methane sorption measurements on organic-rich shale samples at pressures up to 25 MPa and temperatures of 318.1 K, 338.1 K, and 348.1 K.
• Parameterization of excess sorption isotherms using a Langmuir-based function to derive thermodynamic parameters (enthalpy and entropy of adsorption).

Main Results:

• The multi-T method successfully measured methane sorption isotherms on shale under varying temperatures while maintaining constant moisture content.
• Thermodynamic sorption parameters were successfully obtained by fitting the experimental data.
• Explicitly accounting for water vapor pressure in the gas phase led to more thermodynamically meaningful results.

Conclusions:

• The developed multi-T method is a simple, effective, and versatile tool for studying gas sorption in various adsorbent systems.
• The method provides accurate thermodynamic data by considering the role of water vapor, essential for applications like natural gas recovery and carbon capture.
• This approach is particularly advantageous for manometric (volumetric) sorption measurements.