Multiscale pore networks and their effect on deformation and transport property alteration associated with hydraulic fracturing

We performed a series of laboratory and image analysis on organic shale samples before and confined compressive strength tests. Following failure, we often observe an increase in pore volume in the sub-micron range, which appears to be related to the formation of microcracks that in some cases cross or terminate in organic matter, intersecting the organic-hosted pores. Samples with higher clay content tended not to display this behavior. The microcrack networks allow the hydrocarbons to migrate to the main induced tensile fractures. The disconnected nature of the microcracks causes only a slight increase in permeability, consistent with other observations.