Study Of Water Injection Pressure Decreasing By Ultra-low Interfacial Tension Surfactants

According to the problems Jiangsu O ilfield faced when developing low permeability reservoir, an ultra interfacial tension surfactant system with no alkali have been researched. The system has good resistance to dilute, salt and has excellent stability, which can reach ultra interfacial tension to 10-3mN/m with oil from Jiangsu O ilfield. Properties of the system were also evaluated. The results showed that surfactant can absorbed on the rock surface for a long time and flushing resistance ability was good. Decompression life can keep for a long time. The surfactant system can reduce the injection pressure to 38.3%; The higher the core oil saturation is, the extent the decompression will be. The recipe can obviously reduce the oil saturation and reduce the injection pressure. What’s more, it is suitable to the injection well whose oil saturation near the wellbore is more than 40%. Core permeability and oil content of oily wastewater are the two critical factors influencing surfactant life. The lower the permeability is, the higher the oil content of oily wastewater is. The mechanism of decompression and augmented injection was studied, which is, greatly reducing oil- water interfacial tension and the interaction effect between two phases, largely improving the flow of the reservoir permeability. Provide useful reference for developing low permeability reservoirs in Jiangsu O ilfield.