Basic Studies in the Displacement of Residual Oil by Chemical Flooding. Final Report.

摘要

This report summarizes recent observations on the dynamic interfacial properties and their effects on oil ganglia reconnection during surfactant flooding. Studies have been conducted on a number of oil/brine/surfactant systems. These include tests with iso-octane and crude oil oleic phases and several commercial surfactants. Observations to date indicate large variations in eta = kappa + epsilon, the sum of the interfacial dilation and shear viscosities, depending on salt concentrations. The lowest values of eta are observed in the region of optimal salinity where, typically, values on the order of 10 exp -3 s poise, or less, are observed. Outside the region of optimal salinity, significantly larger values are obtained, particularly, at salt concentrations which are below optimal. Droplet-droplet coalescence studies in a spinning drop device also show significant variations in coalescence rate depending on salt concentration. As noted before, the fastest coalescence (or reconnection) is observed in the neighborhood of optimal salinity. Significantly lower rates are observed outside this region with stable emulsions being noted at low salt concentrations. Although surface viscous and elastic effects are important to such processes, it appears that the critical variable is the collapse thickness of the thin film separating adjacent droplets. In general, the results reported here have implications to the kinetics of oil bank formation and to the often observed in situ formation of troublesome stable macroemulsions during surfactant flooding. 14 references, 3 figures. (ERA citation 10:008272)