Integration of Nano Ct and SEM in Study of Marcellus Shale Heterogeneity

Abstract

The increase in exploration and production in shale gas reservoir, and few studies so far reported regarding the general topology of tight reservoir, it is now imperative to critically understand the complexities surrounding the geology of shale reservoirs and its characterization. To understand the transport processes in any shale medium, we need to enhance our knowledge of the geometry and topology of the tight shale rock. The Marcellus Shale has proven to be a major unconventional natural gas play. However, due to its complex bedding orientations, comparatively high clay content and its complex heterogeneity, producing and optimising production is often hindered by its challenging complexities. This paper presents a simplified workflow in the study of the heterogeneity of Marcellus shale rock sample by the combination of Nano CT (Computerized Tomography) imaging and SEM imaging methodologies. A prominent characteristic is anisotropy of the rock fabric which includes distinct differences in the grain sizes, pore geometry and tortuosity. The integration of nano CT reconstruction and SEM imaging technologies in the discretization of unconventional/shale reservoirs will not only help in providing understanding onto the complex geometry of tight reservoirs but also provide intricate insight into understanding adaptable optimum production techniques through flow behavioural analysis and characterisation. The key components involve the uses of an appropriate sample preparation technique, application of complex imaging algorithm in digitising the Marcellus shale sample and 3D image analysis.

Keywords: NANO CT, SEM, imaging, SCAL, SHALE