The combined effects of gravity drainage and component exchange between gas in fracture and oil in matrix on oil recovery in fractured reservoirs subjected to CO2 or nitrogen gas injection are experimentally studied. Laboratory Experiments have been carried out on a 20 cm low permeable outcrop chalk core analogue to one of the North Sea reservoir rock surrounded with a simulated fracture with use of a novel set-up. The experiments aimed to investigate the potential of oil recovery by secondary and tertiary CO2 and nitrogen gas injection at high pressure high temperature condition. The matrix block was saturated using recombined binary mixture live oil (C1-C7), while the fracture was filled with a sealing material to obtain a homogeneous saturation. Sealing material was removed by increasing the temperature which in turn allows creating a fracture surrounding the core. Gas was injected into the fracture for pressures above the bubble point of the oil. Oil recovery as a function of time has been monitored during the experiments.
展开▼
