High-Pressure Methane Adsorption and Characterization of Pores in Posidonia Shales and Isolated Kerogens

Abstract

. (2014) 'High-pressure methane adsorption and characterization of pores in Posidonia shales and isolated kerogens.', Energy fuels., 28 (5). pp. 2886-2901. Further information on publisher's website:http://dx.doi.org/10.1021/ef402466mPublisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Energy Fuels, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/ef402466m. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractSorption capacities and pore characteristics of bulk shales and isolated kerogens have been determined for immature, oil-window and gas-window mature samples from the Lower Toarcian Posidonia Shale formation. Dubinin-Radushkevich (DR) micropore volumes, sorption pore volumes and surface areas of shales and kerogens were determined from CO 2 adsorption isotherms at -78°C and 0°C, and N 2 adsorption isotherms at -196°C. Mercury injection capillary pressure porosimetry, grain density measurements and helium pycnometry were used to determine shale and kerogen densities and total pore volumes.Total porosities decrease through the oil-window and then increase into the gas-window.High-pressure methane isotherms up to 14 MPa were determined at 45, 65 and 85°C on dry shale and at 45 and 65°C on kerogen. Methane excess uptakes at 65°C and 11.5 MPa were in the range 0.056-0.110 mmol g -1 (40-78 scf t -1 ) for dry Posidonia shales and 0.36-0.70 mmol g -1 (253-499 scf t -1 ) for the corresponding dry kerogens. Absolute methane isotherms were calculated by correcting for the gas at bulk gas phase density in the sorption pore volume. The enthalpies of CH 4 adsorption for shales and kerogens at zero surface coverage showed no significant variation with maturity, indicating that the sorption pore volume is the primary control on sorption uptake. The sum of pore volumes measured by a) CO 2 sorption at -78°C and b) mercury injection, are similar to the total porosity for shales. Since mercury in our experiments occupies pores with constrictions larger than ca. 6 nm, we infer that porosity measured by CO 2 adsorption at -78°C in the samples used in this study is largely within pores with effective diameters smaller than 6 nm. The linear correlation between maximum CH 4 surface excess sorption and CO 2 sorption pore volume at -78°C is very strong for both shales and kerogens, and goes through the origin, suggestin...

Data Preprocessing and Its Influence on the Adsorption Capacity of Calculated Shale. Comparison of Selected Methods: A Case Study

“…Nevertheless, results of calculating gas density are available in the literature and are similar to those obtained by the author on raw data (Rexer et al 2014). In this case, the most surprising result is that the calculated density (Table 1) using the raw data is nearly twice the size of that using the preprocessed data -at this point, more detailed studies are necessary.…”

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

“…In order to evaluate the effects of minerals on the methane sorption of shales, it has been shown to be helpful to compare the methane sorption capacities of bulk rock samples and of their isolated kerogen fractions, after normalizing to their TOC values (Rexer et al, 2014;Zhang et al, 2012). In the present work, the three solvent-extracted gas shales and the kerogens they contained were compared for their methane sorption capacities (Fig.…”

“…Successful exploration and production of shale gas in USA has greatly encouraged investigations into the composition (both organic and inorganic) and the gas potential of shales from North America and Europe in the past ten years (Bowker, 2007;Bustin, 2007a, 2008a,b;Curtis, 2002;Gasparik et al, 2014;Hammes et al, 2011;Jarvie et al, 2007;Montgomery et al, 2005;Rexer et al, 2013Rexer et al, , 2014Ross and Bustin, 2007Selley, 2012;Strą po c et al, 2010). In the past few years, Chinese geologists have shown increasing interest in the composition and gas potential of shales (Chen et al, 2011;Han et al, 2013;Wang et al, 2013), and shale gas was licensed as a new type of mineral resource by the Chinese Government in 2011 to accelerate the exploration of shale gas.…”

“…These have suggested that organic matter exerts primary control over sorbed gas, but also indicated the significant effects of organic matter on the pore structure of shales (especially pores at the nanoscale) (Curtis et al, 2012;Loucks et al, 2009;Rexer et al, 2014;Bustin, 2007, 2009;Slatt and O'Brien, 2011;Valenza et al, 2013). The type of organic matter also affects the sorbed methane capacity.…”

“…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).…”