Chapter 6 - Application of the microscopic oil/water distribution model in digital displacement research

Abstract

Research findings have confirmed that the microscopic oil/water distribution model of experimental core is applicable to reservoir cores. Based on the core micro oil/water distribution model, analyzing the digital oil displacement experiment effect, one can clearly see the different partitions range corresponding to the capillary number curve, recovered different micro pore space crude oil of the reservoir during the production, provide a scientific evidence for evaluating oil displacement effect, making plan and improvement measures. This research method has been used to investigate the results of different chemical displacement technologies. In early years, the polymer displacement technology adopted by Daqing Oilfield enhanced oil recovery by around 10% compared to water displacement technology. However, compared to the compound displacement technology, the polymer displacement technology leads to more than 15% of the crude oil remaining underground. Research findings have confirmed that in the case of small injector-producer distance in Daqing Oilfield, the use of the high-viscous ultra-low interfacial tension (1.25×10−3mN/m) displacement system enhances the oil recovery by around 30% compared to water displacement technology. What is produced is almost completely the crude oil stored in the microscopic “pure-oil” pore space of the oil layers. On the other hand, the use of the high-viscous extra-ultra-low interfacial tension (2×10−5mN/m) displacement system can produce not only more crude oil in the microscopic “pure-oil” pore space of the oil layers, but also can produce any crude oil stored partially in the microscopic “oil/water” pore space of the high- and medium-permeability layers.