Influence Of Pore Width On Adsorption Capacity Of Shale-Insights From High Pressure Adsorption Experiments On Model Substances

Shale gas has become an important unconventional resource worldwide and adsorbed gas mainly contribute to the initial gas content for shale. In this study, different model substances, including 3 angstrom molecular sieve, 4 angstrom molecular sieve, 5 angstrom molecular sieve and 13X molecular sieve, were conducted by high pressure methane adsorption experiments and the results were analyzed to obtain the effect of pore width on methane adsorption capacity. The results show that methane molecular almost cannot enter the pore of 3 angstrom molecular sieve for adsorption, only adsorption on surface can be occurred, as well as the pore of 4 angstrom molecular can be slightly entered by methane molecular. Whereas, methane molecular can totally enter the pore of 5 angstrom and 13X molecular for adsorption. Meanwhile, at low pressure (less than 1.0MPa), the excess adsorption amount of methane for 13X is slightly greater than that of 5 angstrom molecular sieve. With the increasing of pressure (1-18MPa), the excess adsorption amount of methane for 5 angstrom is greater than that of 13X molecular sieve. In the pressure ranging from 18 to 30MPa, the excess adsorption amount of methane for 13X is greater than that of 5 angstrom molecular sieve.