PORE CHARACTERISATION,RELATING MINIPERMEABILITY AND CT-SCAN POROSITY OF CARBONATE CORES

摘要

This work was performed on two reservoir carbonate cores.The objectives were to:(i) determine possible functional permeability/porosity relationship at various sampling scales,and(ii) characterise the rocks with respect to mineralogy,pore size distribution and geometry.Scaling was based on mini-permeameter data obtained at cross-section surfaces and along whole cores,and on porosity data contained in computertomography (CT)-scan images each comprising a cross-section of 414x414 values.The other available data included air permeability and Helium porosity on samples of varying size: whole cores,SCAL plugs- and 1-inch plugs.By overlaying the CT images to the corresponding end-face mini-permeability matrix,we sought to determine permeability/porosity correlations at various scales.Pore characterisation was based on thin sections,mercury porosimetry,backscattered electron images(BSE) and X-ray elemental maps obtained from combined scanning electron microscopy (SEM).The analyses revealed highly heterogeneous rocks with wide range of pore sizes that should be described by bi-modal distribution function.The mineralogy showed that core 1 had more calcite with thin layers of calcite cement aligning the pore walls while core 2 was more dolomatized and relatively homogeneous.