Evaluation and research on performance of a blend surfactant system of alkyl polyglycoside in carbonate reservoir

•We contrast the performance of alkyl polyglycoside with other common surfactants.•APG can reduce the interfacial tension between oil and water to a ultralow level.•APG can reverse the interface wettability from hydrophilicity to lipophilicity.•Performance of APG+NaOH is better than APG+NaHCO3 but they differ not quite.•0.5%APG+0.5%NaHCO3 can enhance 6.4% to 7.1% oil recovery value than water flooding.

As a green and efficient surfactant, alkyl polyglycoside (APG) has been applied in many industrial areas due to its green and environment friendly characteristics, which is in accordance with the world-wide sustainable development trend. Up to now, the relative studies were limited in sand reservoirs. In this paper, the performance of APG and the flooding efficiency in carbonate core were experimentally studied.The interfacial tension between water and oil could be effectively reduced to an ultra-low level by APG, and to 2.3×10–3 mN/m by the APG+NaHCO3 system. For the APG+base composite system, the rock interface wettability could be improved and the surface property was transformed from hydrophilicity to lipophilicity. A new system of 0.5%APG+0.5%NaHCO3 was selected to test its ability for the improvement of oil recovery. The oil recovery could be increased about 6.4–7.1% by this binary compound system.