Several countries,including Canada,contain sizeable bitumen resources in highly fractured carbonate rocks.Any possible recovery of bitumen from these reservoirs will be highly dependent on proper understanding of the rock and fluid properties and how they vary in the reservoir.These carbonates are extremely heterogeneous,and as a result proper reservoir characterization is challenging.In this study,a combined approach of x-ray computer tomography and low field NMR were applied on two full diameter native-state cores.CT imaging provides 3-D density and porosity,and maps a detailed distribution of the fracture network and primary,secondary or karst(breccia) porosity,as it varies for different rock types and locations.NMR spectra were acquired along the length of each core,in order to provide water and bitumen saturation predictions,and information about the fluid’s locations in the rock.By combining the CT and NMR results,additional information regarding the fluid saturations and oil viscosity can also be identified.This study demonstrates how the application of CT and NMR technology can be used simultaneously for improved reservoir characterization in complex bitumen-carbonate systems.These techniques could also be extended to interpreting logging tool data acquired in such formations.
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