Is Steamflooding a Form of Low Salinity Waterflooding?

Previously, Al-Saedi and Flori et al. 2018d proposed a novel steam-low salinity EOR technique called low salinity-alternating-steam flooding (LSASF) into a reservoir core with a high reservoir temperature. Naturally, if a reservoir's temperature is very low, then oil is heavy. Using thermal EOR techniques in such a low-temperature reservoir resulted in considerable heat loss. In this study, we investigate the steam lifespan from the injector to the producer in order to check if the injected steam is still active throughout the flooding process or if it will condense because of the heat loss. The Bartlesville Sandstone Reservoir, as with other heavy oil reservoirs, is a low temperature (23°C) shallow reservoir containing heavy oil (600 cP). We believe that steam injected into various cores from the Bartlesville Sandstone Reservoir will condense due to the low reservoir temperature. The question is whether or not this condensed steam behave similarly to low salinity (LS) waterflooding. First, the steam was injected into the oil-free core to determice when the steam condensed and what temperature it condensed at by using a multi-port model to check if the injected steam turned into water. Several Bartlesville Sandstone Reservoir cores were initially flooded with formation water (FW), and then were flooded with different scenarios of steam and LS water. The temperatures of the inlet, the core, and the outlet were recorded. The effluent was collected from different ports out of the cores and different producer positions in order to follow up the steam position inside the core. Core contact angle measurements were conducted throughout the flooded cores to determine the wettability alteration between steam and condensed steam (LS water) with the rock. This study shows that when steam turned into LS water, the sandstone core wettability was altered towards being more water-wet. The condensed steam is considered to be hot LS water, which can reduce oil viscosity and alter the wettability at the same time. These results were for short length cores. If these results are upscaled up to the oil reservoir scale, then the steam will still be turned into LS cold water (LSCW) as will be illustrated in the analytical model (We are still working on the analytical model). The LSCW will work as a wettability modifier only without reducing the oil viscosity. LSCW is not favorable for use in heavy oil reservoirs because the sweep efficiency is very low due to density differences unless the LS water chemistry is manipulated; however, contact angle measurements showed that the LSCW altered the sandstone wettability towards the neutral wet condition.