Effects of crude oil composition on the ASP flooding: A case from Saertu, Xingshugang and Lamadian Oilfield in Daqing

Abstract

In order to evaluate reservoir adaptability of the ASP (alkali/surfactant/polymer) system, its field tests have been carried out in Saertu, Xingshugang and Lamadian Oilfield of Daqing. The results show that crude oil compositions have a great effect on the agent concentration in produced liquid and oil recovery increment. Therefore, this paper researches crude oil composition of three oilfields in Daqing, and the interaction between oil and ASP system. The effect of crude oil compositions on the oil recovery increment and the properties of produced liquid are also further studied. Results show that, the active components of crude oil from three oilfields have the peak feature of typical saturated monocarboxylic acids (fatty acid and naphthenic acid). And there are larger types of organic acids in Lamadian oil active components, from nonane acid to nonacosane acid. In addition, the content of n-alkanes with high carbon component in Lamadian raffinate is larger, and its composition is closer to that of heavy alkylbenzene sulfonate. After the interaction between various crude oil and ASP system, the partition coefficients of surfactant and alkali in Lamadian oil is higher. Besides that, the interfacial tension between ASP system and active components or raffinate are both higher. However, there is ultra-low interfacial tension between ASP system and crude oil. This indicates that synergistic effect exists among the colloid and asphaltene in crude oil and surfactant component, which jointly promotes the substantial decrease in interfacial tension. Furthermore, the field tests have proved the results of laboratory physical simulation experiments.