Laboratory investigation of CO_2 flooding

In order to investigate the mechanism of CO_(2) flooding and provide project data, the phase behavior, viscosity reduction and slim tubule tests were taken to measure the PVT phase behavior of reservoir fluid-CO_(2) mixture, estimate the viscosity reduction effect of CO_(2) and disclose the mechanism of CO_(2) flooding. A method to get eligible reservoir fluid samples is proposed as mixing oil and gas samples to reach the bubble point pressure. Slim tubule tests indicate that it was more appropriate to determine the minimum miscibility pressure through the curve change of oil recovery with flooding pressure. The minimum miscibility pressure of the test, using the oil and gas samples of Shengli Oilfield, was 26 MPa. The tests and literatures show that for a certain reservoir, through a slight manipulation of the measured PVT properties including bubble point pressure, volume factor, swelling factor, solubility of CO_(2) and viscosity, it is possible to obtain single property curves, which can be used to estimated the PVT behavior for any fluid-CO_(2) mixture of this reservoir.