Multiscale (nano to mm) Porosity in the Eagle Ford Shale: Changes as a Function of Maturity

Porosity and permeability are key variables that link the thermal-hydrologic, geomechanical and geochemical behavior in rock systems and are thus important input parameters for transport models. Recent neutron scattering studies have indicated that the scales of pore sizes in rocks extend over many orders of magnitude from nanometer pores with huge amounts of total surface area to large open fracture systems (multiscale porosity, cf. Anovitz et al., 2009, 2011, 2013a, b, Wang et al., – Swift et al., in press). However, despite considerable effort combining conventional petrophysics, neutron scattering and electron microscopy, the quantitative nature of this porosity in tight gas shales, especially at smaller scales and over larger rock volumes, remains largely unknown (Clarkson, 2011). Nor is it well understood how porosity is affected by regional variation, thermal changes across the oil window and, most critically, hydraulic fracturing operations.