Rheological properties and plugging behavior of active crude oil

Water plugging is an important objective in oil field processes owing to the increase in the water content of the produced fluids. Hence, a type active crude oil for water plugging in oil fields was prepared by optimizing the emulsifier and crude oil concentrations. The emulsion stability, rheological properties, and plugging behavior of the active crude oil were investigated. Results showed that the emulsion stability of the active crude oil was affected not only by the composition of the crude oil but also by the hydrophibicity of the emulsifier. Liaohe oil with high contents of asphaltene and resin showed better viscosity–temperature characteristics than the other crude oils and was used to prepare the active crude oil with high viscosity. Sorbitan monooleate (Span80) with long unsaturated alkyl chains showed better emulsion stability than other emulsifiers; the active crude oil emulsion with Span 80 as the emulsifier showed excellent viscosity–temperature properties. The active crude oil formed with Liaohe oil and Span 80 showed better plugging performance for cores with high permeability and for those saturated with water, and the plugging rate was over 99%. The microvisual model clearly showed the emulsification and plugging behavior. Moreover, the oil recovery increased obviously after active crude oil injection into the heterogeneous core.