Application of Modified Non-Ionic Surface Active Agents in Enhanced Oil Recovery

Abstract

ABSTRACT As early as 1954 a study into the efficiency of nonionic detergents to displace crude oil from sandstone reservoirs was published by Dunning. In this study different exethylated alkylphenols were investigated and it was concluded that this calss of surfactants was among the most promising, provided the solubility in the injected waters at reservoir temperatures is sufficient. Since then hardly any investigation into these chemicals were carried out. Practically all work on chemical flooding, both in the laboratory and in the field has been focussed on petroleum sulfonates. Why this investigation into modified nonionics? The main reason is the excellent stability against electrolytes, a feature petroleum sulfonates do not have. By combining the favourable properties of both the nonionics and anionics the so called modified nonionics were introduced for chemical flooding. The products show an excellent stability against electrolytes, especially divalent ions, and no temperature dependence of their solubility. Illustrated by a practical example: sandstone reservoir, average salinity and medium temperature, the development of a flooding recipe based on modified nonionics will be discussed. Attention will be focussed on the laboratory investigation and the optimization of the flooding recipe. It has been shown that a 50% pv slug containing about 0.5% surfactant will give about 35% incremental oil.