In view of the poor development of high-pour-point oil by cold water injection,a high-efficiency surfactant that can form microemulsion with crude oil was used,and the adaptability of the surfactant for enhancing high-pour-point oil recovery was determined through analyzing the surfactant-oil interaction and high-pour-point oil displacements effect by single surfactant,the corresponding combination and foam systems. The results showed that the surfactant IMS with mass fraction of 0.1% could effectively reduce the oil-water interfacial tension to 0.6×10-3 mN/m. The obtained microemulsion could dissolve preferentially the light component of oil,which could not significantly reduce the wax-evolution point and freezing point of the high-pour-point oil. The oil recovery by surfactant huff-n-puff and displacing injection with concentrations of 0.1%—2.0% and utilizations of 0.25—0.5 PV was 1.7%—12.3%,and additional soaking operation could not further improve such oil recovery. The presence of polymer or foam in surfactant solutions could obviously enhance the oil displacement,and the oil recovery by the corresponding binary combination flooding system of 1.0% surfactant+0.2% polymer with the injection volume of 0.5 PV was 18.4%,while those of the surfactant foams with different surfactant concentrations of 1.0% and 0.3% when gas liquid ratio was 2∶1 and the surfactant solution volume was 0.5 PV,were 17.3% and 16.8%,respectively. However,the binary combination flooding behaved a high injection pressure and had underlying injection problem in the low permeability reservoirs,while the foam system performed a relatively low injection pressure and could enhance oil recovery effectively.
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LI Qiang, DING Mingchen, ZHANG Xing, WU Hanchao, CHEN Lixia, WANG Yefei. Adaptability of an In-situ Microemulsion Surfactant in Displacing the High-pour-point Oil from Low Permeability Reservoir[J]. OILFIELD CHEMISTRY,2022,39(3):474-479.