Study of Two Phase Fluid Flow in Water Wet Reservoir Rocks by Using X-Ray In situ Saturation Monitoring

Displacement of oil and water in porous media of reservoir rocks is described by relative permeability curves, which are important input data for reservoir performance simulation and drive mechanism studies. Many core studies, such as multiphase relative permeability, capillary pressure and saturation exponent determination, depend on the volume fractions of multiphase fluids present in the studied rock samples. X-ray scanners are increasingly used for measurement of fluids saturation in the core samples during core studies, mainly due to expanding need of modeling and measuring reservoir condition fluid flow behavior and its being safer issues than other radioactive sources like gamma ray. Incorporating X-Ray in situ saturation measurements into the relative permeability, capillary pressure and intrinsic wettability characterization of reservoir rocks may improve reservoir management and productivity prediction. This paper describes two phase immiscible fluid flow behavior of oil displaced by water through water wet porous media interpreted by X-ray data utility, according to saturation profile shapes incorporated by history matching of oil production and differential pressure history in low oil to water viscosity ratio fluid flow. In situ saturation profiles have been obtained with 1% saturation accuracy. The in situ saturation profiles confirm wettability character of reservoir rock samples and are an indication of the fact that initial water saturation and non-wetting oil phase values are controlled by reservoir rock wettability characteristics. The immovable water saturation increases because of oil snap-off and when light oil enters a water wet porous media, even increasing the oil injection rate cannot overcome van der Waals forces throughout water molecules. The saturation profiles have been shaped rather flat after water breakthrough. These profiles attribute to the recovery of the bulk of oil before breakthrough in low viscosity ratio displacement through water wet rocks. Besides, overlapping of various after bump saturation profiles indicates that there is no significant difference between remaining oil saturation and residual oil saturation in water wet reservoir rocks.