| East Block 25 is the reservoir of high temperature, high salinity, high calcium and magnesium, strong heterogeneous. Its main reservoir stimulation profile with better conditions for the development of a Class I and II reservoirs, the reservoir has entered the high water cut stage. To improve the comprehensive high water cut stage reservoir recovery, Zhongyuan Oilfield developed a complex of low tension surfactant gel microsphere emulsion flooding system. The system can be integrated to play an integral part in the contribution of the "tone" and "drive" aspects of flooding is a high performance system.Performance testing is latex microspheres by laser particle size analyzer and scanning electron microscope observation system microsphere size, particle size distribution with the variation of external conditions. The test results show that the polymeric microspheres with swelling time increases, the first slow down the rapid expansion and then expanded, the expansion of nearly 30 days to several hundred nanometers and is relatively stable; expansion times more than 10 times; microsphere size has better salt and temperature resistance.Mechanism of oil displacement is verified from 3 aspects which are the microscopic, horizontal single tube heterogeneity and two-dimensional flat plate, its flooding mechanism is:an elastic polymer microspheres are spherical, small particle size, water swelling, relying on bridge and expansion of the role of stratigraphic holes were clogged throat, when the large size microspheres to form bridges, the smaller size of the microspheres in the formation of small holes lane bridge is embedded and clogging rely polymer microspheres elasticity and plasticity, stretch occurs a strong action to enhance the mechanical strength of the wedge plug, forming a strong movement of the plug-like cushion difficult to achieve the purpose of blocking, in order to achieve microscopic redirection injected water, at the same time, with the micro-injection Ball volume increased, swelling and squeezing between the microspheres, slow the inflow channel, and can be "clear" a small amount of residual oil, after the microspheres beyond its elastic deformation, with the injection of water, with repeated cycles of action, by temporarily blocking, deformation, migration, and then temporarily blocked, and then deformed, and then transport mechanism, such as starting the process repeated flooding effect, so microspheres "note to get there, blocking is maintained, can move" feature.Reservoirs adaptability microspheres emulsion from three aspects of the various systems, heterogeneity and heterogeneity and heterogeneity comparative experiments started comparing a single injection of the microspheres, a single injection of surfactant, low tension microspheres emulsion system microspheres and surfactant alternating injection injection and oil displacement efficiency, and the use of latex microspheres and surfactant 1:1 alternating injection highest recovery value, therefore, the use of latex microspheres and surfactant 1:1 alternative injection system more adapted to the field reservoirs. At the same time, the heterogeneity of 1:1.1,1:1.5,1:2.5,1:4,1:6 and other five poor penetration twin tube model experiments to study the reservoir heterogeneity, the results show when poor penetration of small polymeric microspheres emulsion system mainly to "tune" the main, "drive", supplemented by the way; and in poor penetration is increasing, flooding methods have to "drive" for the changes in the main "tune" supplementary means. The heterogeneity of the tiny, small, medium, large, extremely poor, such as twin-tube experiments with homogeneous flooding conditions 300mD,500mD,800mD single tube flooding experiments were compared, the results showed that the microspheres are more adapted to the non-emulsion homogeneous reservoirs.In order to facilitate the injection parameter optimization, first determine the aging time after injection agent, respectively, comparing aging 12h,24h, injection and oil displacement efficiency and other three aging time 48h, and 24h after the results to determine the optimal aging Injecting aging time; section Preferred plug from slug injection rate (0.3PV,0.5PV,0.7PV,1PV) and plug combination segment (polymer microspheres and surfactant ratio of 1:1,2:1,1:2,1:1:1:1) two preferred aspects, the results show that the slugs and slug injection rate 0.5PV combination ratio of 1:1 for the best slug; four kinds of contrast injection rate (0.3ml/min,0.5ml/min, lml/min, 2ml/min) were flooding experiment, the results show that the use of 0.5ml/min for the optimum injection rate; in the preferred slug, under speed conditions, the degree of change in the flow control agent (microspheres) concentration (0.3%,0.5%,0.7%), surfactant concentration of 0.3% constant 1:1 alternating injection, the results showed that 0.5% of microspheres for the best latex microspheres injected concentration... |
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