| This article is in view of the low permeable oil fields of northern Songliao Basin, which has big reserves, complicated pore structure, formation energy shortage and poor liquidity, etc.Conventional waterflood recovery efficiency is low, oil change rate is poor, water breakthrough rapidly. One-time investment in chemical flooding is large. Chemical flooding injection capacity is poor, cost is huge, matching technology is complex, use conditions are limited. Through the experiment research of non hydrocarbons CO2 at home and abroad,which shows that it can extract the light components in the crude oil step by step and dissolve in crude oil to completely miscible. In the process of miscibility, CO2 can reduce viscosity of crude oil, improve the mobility ratio of crude oil and water, make crude oil volume expansion,extraction and evaporation light hydrocarbons in crude oil, achieve miscible effect, reduce the oil-water interfacial tension, function dissolved gas drive, improve recovery efficiency. So this topic has carried out water flooding, CO2 flooding（miscible flooding and immiscible flooding）, water/CO2 flooding, CO2 stimulation four injection patterns are studied.Experiments are quantitative and qualitative researched by injection pressure, injection rate,production pressure（differential pressure）, injection slug, water/gas ratio, soak time. Evaluate oil displacement result and mechanism of oil displacement is studied mainly from the oil recovery, oil change rate, gas-oil ratio, injection ability, water content and other comprehensive index. This paper mainly studied minimum miscible pressure, expansion experiment, start-up pressure and four kind injection mode of the purpose block. And according to the characteristics of purpose block and experimental results, determine the water/gas alternating flooding is the best way of exploitation, and determine the reasonable injection slug and reasonable producing pressure drop. |
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