Experimental Study On Oil - Water Mixed Flow Characteristics Of Fractured Complex Medium

This subject is part of the Key Technologies R&D Program of SINOPEC which entitled "key technologies in the development of complex fractured carbonate reservoir". As one of complex reservoir, it is necessary to research it intensively. Compared with conventional porous reservoirs, fractured carbonate reservoirs are more heterogeneous, and fluid flow behavior and oil-water relationship is complex. So the development of fractured carbonate reservoirs is rather difficult, and it is researching at home and abroad. It is of great importance to research fluid flow mechanism of fractured carbonate reservoirs.This paper focuses on the research of water flooding characteristic in fractured carbonate reservoir. Based on the similarity criterion and water flooding physical modeling cases, we have designed and made up the small and large sized fracture network model. By the analysis of laboratory water flooding experiment and results, we have correctly studid and evaluated the water flooding character and flow mechanism.This thesis has drawn the following results:1) Developed a visual physical model which suitable for studing mechanism of fluid flow in fracture system.The models were designed of both small and large size in accordance with the geological features of Chegu area of Futai field.And also take fracture characteristics including trend, dip angle, density, width and interspacing into account.2) A series of experiments were performed based on the small-sized model.A series of experiments were performed to study the impact of fracture width, fracture range, angle, and different fracture network on the flow behavior in fracture system.Besides, analyzation was conducted qualitatively about the percolation mechanism in fracture network as well as residual oil distribution after waterflood.3) The behavior of fluid flow in fracture were studied with large sized visual model.In this section, the displacement efficiency, water cut trend, residual oil distribution as well as fluids flow behavior was obtained which were tested under different fracture aperture and fracture network.4) The relative permeability curve under different fracture aperture and different fracture network was studied.The relative permeability curve were obtained by the use of nonsteady state method. Varying pattern and controlling factors of the relative permeability were analyzed, optimal model suitable for fracture system was also obtained by fitting experimental data with theoretical model.With studying flow behavior in different fracture network, the present work describes flow behavior of formation fluids,waterflooding process, displacement efficiency as well as waterflooding mechanism and recovery in the network of fracture, have great significance to the exploitation by water flooding and plan adjustment for fractured reservoir.