Experimental investigation of main controls to methane adsorption in clay-rich rocks

Methane Adsorption Rate and Diffusion Characteristics in Marine Shale Samples from Yangtze Platform, South China

“…As illustrated in Figure 4, the methane adsorption isotherms for shale samples indicate that the adsorption trend followed Type I isotherm behavior. Generally, the trend of highpressure methane adsorption isotherms showed a significant increase in the adsorption amount at low pressure and then flattened out into a plateau region at high pressure [40,[44][45][46], which is believed to have been caused by the overlapping adsorption potentials between the walls of pores with similar diameters to the adsorbate molecules at low pressure and by the gradual formation of monolayers of methane molecules at high pressure [47]. In this study, however, the measured shale samples showed a steady increase and did not attain saturation at the final experimental pressure of about 7.5 MPa, with the exception of shale sample YY2-1, which exhibited a maximizing trend within the range of experimental pressures ( Figure 4).…”

“…The volumetric method is based on mass balance principles and requires precise measurements of pressure, volume, and temperature. The instrument's components, in terms of the volumetric method, have been documented in previous literature [11,40]. In this experiment, the main procedures can be summarized as follows: (1) the shale powder samples need to be degassed firstly by evacuation for 12 h at 100 • C; (2) leak testing should be conducted by using helium at 8 MPa for two hours, and the accepted leakage rate is less than 500 Pa/hour; (3) the void volume of the sample cell, which should be applied for the calculation of isotherms and methane adsorption amounts, was determined by helium expansion; and (4) remove the helium within the sample cell by evacuation and then perform the methane adsorption isotherm measurement.…”

“…The characterization of gas adsorption is generally described through isotherms, i.e., the amount of adsorbate (methane) on the adsorbent as a function of pressure. The Langmuir equation is a model that relates the adsorption of gas molecules on a solid surface to gas pressure at a given temperature [40]. Assuming that methane adsorption in organic-rich shales follows the monolayer adsorbate theory, the methane adsorption experimental results can be modeled by the Langmuir isotherm equation [42]:…”

“…The Langmuir parameters (V L and P L ), which were obtained from the least-squares fit of methane adsorption isotherms, are listed in Table 3, with values ranging from 2.37 cm 3 /g to 5.55 cm 3 /g and 2.6105 MPa to 6.1741 MPa, respectively. According to previous studies [9][10][11]40,45,[48][49][50][51], the Langmuir methane adsorption volume of organic-rich shale is controlled by a number of interior and external factors, including the shale matrix (heterogeneous mixture of organic and inorganic) and reservoir's temperature and pressure. In particular, organic matter with a microporous structure is the dominant factor that controls the methane adsorption capacity of organic-rich shales.…”

The composition and its impact on the methane sorption of lacustrine shales from the Upper Triassic Yanchang Formation, Ordos Basin, China

“…Some clay minerals, e.g. montmorillonite and illite, have abundant micropores and also a high methane sorption capacity (Ji et al, 2012;Liu et al, 2013;Lu et al, 1995;Ross and Bustin, 2009), and have been reported to contribute to the methane sorption on shales when measured on a dried basis (Chalmers and Bustin, 2008a;Gasparik et al, 2012;Rexer et al, 2014).…”