Impact of Mud Filtrate Invasion on Rock Characterization by Resistivity Laboratory Measurements

Summary The invasive process of mud filtrate alters the physicochemical characteristics of the formation and divides it into four zones: mud cake, flushed zone, transition zone and virgin zone. Therefore, all well logging measurements are influenced by mud filtrate invasion. This paper aims to identify the impact of crude-glycerin-based aqueous mud filtrate on resistivity logs by laboratory measurements. Resistivity laboratory measurements were made on Berea sandstone samples in brine and mud filtrate saturated conditions. The crude-glycerin-based aqueous mud filtrate had an impressive performance in the resistivity since the samples saturated with this mud filtrate (flushed zone) showed electrical resistivity 3.6 higher than the resistivity of brine saturated sandstone samples (water zone). This mud can perform well, as an advantageous drilling fluid, because of the high water-oil resistivity contrast.