| Machined fragments of 10 core plugs from offshore reservoirs have been analysed using a high resolution X-ray micro-computed tomography (micro-CT) facility. The facility includes a system capable of acquiring 3D images made up of 20003 voxels on core plugs up to 6 cm diameter with resolutions down to 2 mum. The cores analysed include six cores from a gas reservoir and four cores from an oil reservoir. The cores exhibit a very broad range of pore and grain sizes, porosity, permeability and mineralogy. The petrological data, available only for gas reservoir cores, is compared with the data obtained from the tomographic images.; Computational results made directly on the digitized tomographic images are presented for the permeability, formation factor, resistivity index and drainage capillary pressure across a range of &phgr;. We show that data over a range of porosity can be computed from a single fragment. We compare the computations of petro-physical data on fragments to conventional laboratory measurements on the full plug. Permeability predictions from digital and conventional core analysis are consistent. It is shown that a characteristic length scale can be defined as a quality control parameter for the estimation of permeability. Results for formation factor, drainage capillary pressure and resistivity index are encouraging. (Abstract shortened by UMI.)... |
