Wettability State and Phase Distributions During Steam Injection with and without Chemical Additives: An Experimental Analysis Using Visual Micromodels

Summary Phase change plays an essential role in wettability during steam injection, and oil becomes the wetting phase in the steam zone. This study investigates this unfavorable phenomenon using visual data obtained from micromodel experiments and how the wettability can be reversed using chemicals. All measurements were conducted at temperatures up to 200°C on glass-bead micromodels. The models were initially saturated with brine solution and then displaced by two types of mineral oils (450 and 111,600 cp at 25°C). Steam was then constantly injected into the micromodels to evaluate the effect of phase change and wettability status on residual saturation development. Next, chemical additives, screened from the previous contact-angle and thermal-stability measurements, were added to the steam to observe their ability in modifying phase distribution and wettability state. The results showed that phase distribution and residual oil saturation are critically sensitive to the steam phase. At any circumstances, wettability alteration with chemicals was possible. The shape and characteristics of the trapped oil with and without chemicals were identified through micromodel images, and suggestions were made as to the conditions (pressure, temperature, and time to apply during the injection application) at which these chemicals show optimal performance.