RELATIVE PERMEABILITY, CAPILLARY PRESSURE AND USBM WETTABILITY INDEX DETERMINATION IN A HIGHLY ASPHALTENIC OIL RESERVOIR

Most of the troubles concerning determination of water-oil relative permeability and capillary pressure of reservoir rocks arise from discrepancies in thewettability of studied reservoir and measured laboratory data, which makes the results unreliable and doubtful. In core study experiments, when livereservoir oil is out of reach, dead crude oil is mainly used to establish reservoir wettability. But most of the times it is unusable for relative permeability andcapillary pressure experiments. In this study the effect of using highly asphaltenic dead crude oil on the relative permeability, capillarypressure and USBM wettability index experiments was investigated by applying the restored-state approach. The tests were performed on some coreplug samples of a carbonate reservoir from the South- West of Iran. Due to asphaltene and resin precipitation and clogging in the pore spaces norepresentative results were obtained, hence, buffer solvent was injected into the samples to remove the bulk of crude oil before using synthetic mineral oilfor performing the experiments. The recorded data from relative permeability experiments were simulated by Sendra core flow simulator andcompared with conventional Jones and Roszelle calculation method. Both USBM and Craige rules of thumb showed oil-wetness characteristics.