| Summary: | By tracking and analyzing the research and practices of chemical flooding carried out in the Daqing Oilfield, NE China since the 1970s, the chemical flooding theory, technology adaptability and existing problems were systematically summarized, and directions and ideas of development in the future were proposed. In enhanced oil recovery by chemical flooding, the Daqing Oilfield developed theories related to compatibility between crude oil and surfactant that may form ultra-low interfacial tensions with low-acidity oil, and a series of surfactant products were developed independently. The key technologies for chemical flooding such as injection parameter optimization and numerical simulation were established. The technologies of separation injection, cleansing and anti-scaling, preparation and injection, and produced liquid processing were developed. The matching technologies of production engineering and surface facilities were formed. Through implementation of chemical flooding, the Daqing Oilfield achieved outstanding performances with enhanced recovery rate of 12% in polymer flooding and with enhanced recovery rate of 18% in ASP flooding. To further enhance the oil recovery of chemical flooding, three aspects need to be studied: (1) fine characterization of reservoirs; (2) smart and efficient recovery enhancement technologies; (3) environment friendly, high-efficiency and smart matching processes. Key words: Daqing Oilfield, chemical flooding, surfactant-oil match theory, injection parameter optimization, engineering support technology, enhanced oil recovery
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