A Novel Method with Dilute Surfactant Flooding by Considering the Effect of Time and Temperature on Crude Oil Aging, Experimental Study on Heavy Oil of Bangestan

Abstract

Wettability alteration has been a sophisticated issue for scientists and reservoir engineers since early 20th century; thus, many investigations have been carried out to determine wettability and enhance it to ideal conditions, which leads to improvement in oil recovery. Dilute surfactant flooding has been approved as one of the noteworthy methods in chemical flooding. Several petroleum reservoirs were recognized as suitable nominees for surfactant/water flooding when screening criteria were established. Surfactant flooding was applied to mobilize the trapped oil in reservoirs. The key mechanism to enhance oil recovery by surfactant flooding was defined as rock wettability alteration. Experimental investigations into the impact of aging and temperature on wettability alteration were performed. Subsequently, core flooding test of surfactant was performed to define the effect of thinned cationic surfactant slug with cyclic 7 days technique (Multi-slug injection) on displacement sweep efficiency in the carbonate core of Bangestan reservoir with its heavy oil reservoir. Moreover, contact angle and interfacial tension (IFT) measurements were made to gain the supplementary information for a surfactant/waterflooding. The best concentration of C19TAB was determined by measuring interfacial tension values of the crude oil in contact with surfactant solutions prepared in synthetic brackish water. Results displayed a decrease in residual oil saturation by changing the contact angle and IFT reduction between oil and water. Moreover, aging was known as a significant constraint to change the wettability index to make similar oil-wet condition. Besides, laboratory experiments verified that the influence of wettability alteration was higher than IFT reduction.