Chemical flooding technology has been widely applied in medium- and high-permeability reservoirs. However, it is rarely applied in low-permeability reservoirs, which is mainly limited by reservoir physical properties, chemical agents, injection capacity, and so forth. In this paper, a novel chemical formula used in low-permeability reservoirs was developed. In response to the low-permeability reservoir geological characteristics, fluid properties, and water flooding development of the target block, some experimental studies and field project studies of polymer–surfactant flooding were carried out. The surfactant structure and polymer molecular weight were determined from laboratory experiments. The polymer–surfactant binary system was synthesized. It had good injectivity in low-permeability reservoirs, and its oil recovery efficiency increased over 10% in the laboratory experiment. The result was higher than that of single chemical flooding. After field implementation, initial results have been achieved with an increase in injection pressure. The chemical formula can effectively alleviate intra-layer and inter-layer contradictions in the reservoir. The project has increased oil output by 77,700 t and the recovery factor by 3.5%. The experience and lessons were of great significance for the development of chemical flooding in high-temperature, high-salinity, and low-permeability reservoirs.

中文翻译：

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低渗透油藏中的聚合物-表面活性剂驱：一项实验研究

化学驱技术已广泛应用于中高渗透油藏。但在低渗透油藏中应用较少，主要受限于油藏物性、化学药剂、注入能力等。在本文中，开发了一种用于低渗透油藏的新化学式。针对目标区块低渗透储层地质特征、流体性质、注水开发等特点，开展了聚合物-表面活性剂驱实验研究和现场工程研究。表面活性剂结构和聚合物分子量由实验室实验确定。合成了聚合物-表面活性剂二元体系。在低渗透油藏中具有良好的注入性，在实验室实验中，其采油效率提高了10%以上。效果优于单一化学驱。现场实施后，随着注入压力的增加，取得了初步成果。化学式可有效缓解储层内层内层间矛盾。该项目增产石油7.77万吨，采收率提高3.5%。经验教训对开发高温高盐低渗油藏化学驱具有重要意义。化学式可有效缓解储层内层内层间矛盾。该项目增产石油7.77万吨，采收率提高3.5%。经验教训对开发高温高盐低渗油藏化学驱具有重要意义。化学式可有效缓解储层内层内层间矛盾。该项目增产石油7.77万吨，采收率提高3.5%。经验教训对开发高温高盐低渗油藏化学驱具有重要意义。