Document Type : Research Paper
Northeast Petroleum University, Daqing , China
School of Marine Sciences, Sun Yat-sen University, Guangzhou, China
Northeast Petroleum University, Daqing, China
Key Lab of Mineral and Mineralization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou , China
To observe and study the distribution characteristics of remaining oil in pores of late stage of development more intuitively and clearly, this paper proposes an observation and quantitative characterization method of occurrence states of remaining oil on pore scale. With liquid nitrogen freezing technology, core columns are frozen immediately after displacement experiment. The samples are ground to thickness of 0.05mm under frozen condition. Distributions of oil and water in pores are observed with technology of ultraviolet fluorescence micro photography, and remaining oil content of different types is quantitatively calculated by analysis of characteristic parameters of core image. Quantitatively analysis of the laboratory displacement experimental results indicates the average oil recovery reaches over 48% after water flooding, and the main types of the remaining are throat state, cant state, state of thin film on pore surface, cluster state, interparticle adherence state and particle adherence state, their relative contents account for 1.84%, 3.07%, 37.42%, 5.83%, 27.91% and 24.23% of total remaining oil reserves respectively. Among them, remaining oil of thin film on pore surface, remaining oil of interparticle adherence and remaining oil of particle adherence with high content are the development targets for further enhanced oil recovery. This research is of great significance on further enhancing oil recovery.