Porosity of Coal and Shale: Insights from Gas Adsorption and SANS/USANS Techniques

Two Pennsylvanian coal samples (Spr326 and Spr879-IN1) and two Upper Devonian-Mississippian shale samples (MM1 and MM3) from the Illinois Basin were studied with regard to their porosity and pore accessibility. Shale samples are early mature stage as indicated by vitrinite reflectance (Ro) values of 0.55% for MM1 and 0.62% for MM3. The coal samples studied are of comparable maturity to the shale samples, having vitrinite reflectance of 0.52% (Spr326) and 0.62% (Spr879-IN1). Gas (N2 and CO2) adsorption and small-angle and ultrasmall-angle neutron scattering techniques (SANS/USANS) were used to understand differences in the porosity characteristics of the samples. The results demonstrate that there is a major difference in mesopore (2–50 nm) size distribution between the coal and shale samples, while there was a close similarity in micropore (<2 nm) size distribution. Micropore and mesopore volumes correlate with organic matter content in the samples. Accessibility of pores in coal is pore-size specific and...

[1]  Maria Mastalerz,et al.  Characterization of tight gas reservoir pore structure using USANS/SANS and gas adsorption analysis , 2012 .

[2]  R. Marc Bustin,et al.  Selective transport of CO2, CH4, and N2 in coals: insights from modeling of experimental gas adsorption data , 2004 .

[3]  A. Radlinski.  Small-Angle Neutron Scattering and the Microstructure of Rocks , 2006 .

[4]  Maria Mastalerz,et al.  Accessibility of pores in coal to methane and carbon dioxide , 2012 .

[5]  E. Voutsas,et al.  Water/Hydrocarbon Phase Equilibria Using the Thermodynamic Perturbation Theory , 2000 .

[6]  Philip L. Walker,et al.  Nature of the porosity in American coals , 1972 .

[7]  C. Boreham,et al.  Small angle neutron scattering signature of oil generation in artificially and naturally matured hydrocarbon source rocks , 2000 .

[8]  Maria Mastalerz,et al.  Variations in pore characteristics in high volatile bituminous coals: Implications for coal bed gas content , 2008 .

[9]  T. Blach,et al.  Stability of the bituminous coal microstructure upon exposure to high pressures of helium , 2009 .

[10]  R. Bustin,et al.  Geological controls on coalbed methane reservoir capacity and gas content , 1998 .

[11]  M. Mastalerz,et al.  Dynamic micromapping of CO2 sorption in coal. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[12]  M. Agamalian,et al.  Design and performance of a thermal-neutron double-crystal diffractometer for USANS at NIST , 2005 .

[13]  H. Amenitsch,et al.  The new high resolution ultra small angle neutron scattering instrument at the high flux reactor in Grenoble , 2000 .

[14]  E. Barrett,et al.  (CONTRIBUTION FROM THE MULTIPLE FELLOWSHIP OF BAUGH AND SONS COMPANY, MELLOX INSTITUTE) The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms , 1951 .

[15]  M. Mastalerz,et al.  Application of SAXS and SANS in Evaluation of Porosity, Pore Size Distribution and Surface Area of Coal , 2004 .

[16]  P. W. Schmidt,et al.  Interpretation of small-angle scattering curves proportional to a negative power of the scattering vector , 1982 .

[17]  M. Mastalerz,et al.  Pore accessibility by methane and carbon dioxide in coal as determined by neutron scattering , 2012 .

[18]  Bertram,et al.  The use of multiple-scattering data to enhance small-angle neutron scattering experiments. , 1999, Acta crystallographica. Section A, Foundations of crystallography.

[19]  Harold D. Bale,et al.  Small-angle X-ray-scattering investigation of submicroscopic porosity with fractal properties , 1984 .

[20]  Christopher R. Clarkson,et al.  Variation in micropore capacity and size distribution with composition in bituminous coal of the Western Canadian Sedimentary Basin: Implications for coalbed methane potential , 1996 .

[21]  Dudley D. Rice,et al.  Hydrocarbons from coal , 1993 .

[22]  Christopher R. Clarkson,et al.  The effect of pore structure and gas pressure upon the transport properties of coal: a laboratory and modeling study. 1. Isotherms and pore volume distributions , 1999 .

[23]  Maria Mastalerz,et al.  Characterization of the CO2 fluid adsorption in coal as a function of pressure using neutron scattering techniques (SANS and USANS) , 2009 .

[24]  A. Hinde.  PRINSAS – a Windows-based computer program for the processing and interpretation of small-angle scattering data tailored to the analysis of sedimentary rocks , 2004 .