Petrographic Investigation on Pore Throat Size Distribution of the Ultra-low Permeable Reservoirs
Abdur Razak Ibrahim and Mohamad Nur Saufi Mohamad Aris, Honours 2014
Australian School of Petroleum
University of Adelaide
The purpose of this investigation is to study the mineralogy and rock mechanical properties of the ultra-low permeable reservoir. A tight gas sample from Epsilon Formation specifically at Holdfast 1 at 3219 m of depth from Cooper Basin was analyzed. The methods used in this report include FIB/SEM, backscattering method and characteristic x-ray analysis to provide a better understanding of elemental analysis in term of pore texture and minerals present in this tight gas sample. Moreover, the wireline logs data of the Epsilon Formation from Holdfast 1 at depth interval of 3171.6m to 3341.1m was obtained to briefly describe brittleness concept by determining the rock mechanical properties specifically the Poisson's Ratio (v) and Elastic Young's Modulus (E).
Results from the investigation have shown that clays such as kaolinite, illite and chlorite present in the sample as major clay constituent. The influence of clay minerals has both positive and negative impacts on permeability and porosity of the tight gas reservoir. Besides, determination of the rock mechanical properties evaluated brittleness of the rock in tight gas sands which could affect by the minerals present in the formation. The combination of Poisson's Ratio and Elastic Young's Modulus reflect the ability of the rock to fail under stress and maintain a fracture opening during hydraulic fracturing. These mechanical properties have strong impact on hydraulic fracturing as the only way to produce gas from unconventional reservoir at an economic rate.