| Presently both home and abroad, few examples of successful exploiting reservoirs for the EOR technologies to be applied in abnormal high temperature and high water salinity, it is number one for study of water alternating gas (WAG) flooding of high permeability reservoirs in high water-cut stage, very difficult development of them induce this technology is far from perfect, and has not yet formed its mature theory, idea, technology or methods. This paper took the Pucheng east ershang reservoir as the practical example, comprehensively applied such theories or methods as the mathematics model of multi-objective decision-making, oil reservoir engineering, petroleum engineering, advanced indoor laboratory equipments and experimental analysis and reservoir simulation technology as well. Analyzing and studying the mechanism of WAG flooding and the optimization of parameters etc., this paper established the reservoirs choosing evaluation systems, the methods for calculating production and injection capacity by reservoir engineering theories, thus presented a series of research ideas and measures for WAG flooding. The main harvests achieved in this paper are as follows:1. Has studied the WAG microscopic and macroscopic mechanisms from the rationale . WAG miscible flooding basic mechanism is the displacement medicinal preparation and is formed by the displacement medicinal preparation under the oil deposit condition miscible, the elimination contact surface, causes in the porous medium capillary forces to fall to zero, thus reduces because the capillary tube effect to produce the petroleum which the capillary vessel is detained traps; Immiscible displacement the main displacement mechanism is the volume expansion, the viscosity reduces with the gravity stably drives; The different displacement number of times, the single inferior injection rate, the water-gas ratio and the stratic rhythm and heterogeneity and so on, all to drives the oil efficiency to have a more tremendous influence.2. Has analyzed the influence note natural gas drive main geologic agent using numerical simulation software, has determined each influence factor weight coefficient using the comparative law of the antithesis; have carried on quantitative appraisal to the objective geological condition influencing gas flooding with the mathematics model of multi-objective decision-making, established a set to suit to the Zhongyuan oil field WAG candidate oil reservoir half quantitative evaluation method. Using this method optimal Pucheng ES2U Reservoir for the WAG EOR area in turn.3. Based on the vertical pipe flow formula, the computation biggest bottom of the well pours into the flowing pressure is 33.12-34.96MPa; The application nodal analysis completed the gas drive note to pick the ability research, the computation biggest injection rate of gas is5.6×10~4m~3.4. In the room the physical analogue research indicated that, this area belongs to the model the black strap oil deposit; the water drive recovery ratio is 50.39%; The note gas driving cannot carry on miscible flooding ; Under the present condition, the implementation WAG Immiscible displacement may enhance the oil recovery ratio 12.22 percentage points; The water drive less WAG, the injection pressure increases 0.6 time.5. The numerical simulation pours into the parameter optimization result recommendation plan, uses 0.15HCPV (hydrocarbon poro volume) WAG flooding, 3 plug pours into, the gas injection rate is 50000m~3/d, and water injection rate is 245m~3/d.The research results achieved in this paper have been successfully applied in ZhongYuan oil field to enhance oil recovery study buy WAG. The result conducts shows: the research methods in this paper are reliable, applicable and operational, and will bring to the oil fields much economic benefits. Meanwhile, the research methods and procedures, embodied in the study of the WAG technologies in the high permeability reservoirs in high water-cut stage, provide a significant guide for the study of WAG flooding in other similar or dissimilar oil fields in our nation.
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