Pore geometry and connectivity in shaly sand as input data for fracking experiments

Abstract

Exploration for hydrocarbon in shales is an example of unconventional reservoirs for oil and gas resources with huge amount of commercial potential. Porosity and permeability in shale are two important factors that control fluid accumulation and flow. To get the natural shale samples from wells is certainly a hard and crucial job for reservoir fracking studies. To study different factors that influence pore types and geometry in fracking experiments, we carried out X-ray Diffraction (XRD) analysis, surface area analyzer and porosimetry system (SAP), poroperm and tomographic imaging (micro-CT scan) on shale samples from Peninsular Malaysia. The results of synthetic cores through XRD show high amount of clay content (illite/smectite, and kaolinite) and quartz. Other experimental studies reveal that porosity and permeability is heterogeneous and low in the interbedded shale due to very-fine grained matrix. Microscale studies using SEM and CT scan demonstrate different types of pores that are inter/intragranular, intercrystalline, and organic. Our results elucidate that interconnecting pores and their permeability for fluid flow is low due to the obstruction by very-fine grains of clay minerals like illite and kaolinite in shaly sand. The results can be directly applied to labbased fracking experiments that can provide optimal fracking parameters and has great potential in the (oil and gas) O&G industry for understanding hydrocarbon (HC) flow dynamics