Mechanisms of Enhanced Oil Recovery by Surfactant-Induced Wettability Alteration |
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Authors: | Baofeng Hou Xulong Cao Jun Zhang Xinwang Song Mingchen Ding |
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Institution: | 1. School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, China;2. Geoscience Research Institute of Shengli Oilfield Company, SINOPEC, Dongying, China;3. School of Science, China University of Petroleum (East China), Qingdao, China |
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Abstract: | Different measurements were conducted to study the mechanisms of enhanced oil recovery (EOR) by surfactant-induced wettability alteration. The adhesion work could be reduced by the surfactant-induced wettability alteration from oil-wet conditions to water-wet conditions. Surfactant-induced wettability alteration has a great effect on the relative permeabilities of oil and water. The relative permeability of the oil phase increases with the increase of the water-wetness of the solid surface. Seepage laws of oil and water are greatly affected by surfactant-induced wettability alteration. Water flows forward along the pore wall in the water-wet rocks and moves forward along the center of the pores in the oil-wet rocks during the surfactant flooding. For the intermediate-wet system, water uniformly moves forward and the contact angle between the oil–water interface and the pore surface is close to 90°. The direction of capillary force is consistent with the direction of water flooding for the water-wet surface. While for the oil-wet surface, the capillary force direction is opposite to the water-flooding direction. The highest oil recovery by water flooding is obtained at close to neutral wetting conditions and the minimal oil recovery occurs under oil-wet conditions. |
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Keywords: | Adhesion work capillary force EOR mechanisms relative permeability seepage laws surfactants wettability alteration |
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