Laboratory Experiment And Field Test On CO₂Huff And Puff

Oil reservoir of block X in L oil field has low porosity, low permeability, severelyheterogeneity, and there are multiple unformed small block reservoir of injection-productionsystem. With the gradually deeply study of mining, the production of mining face manyproblems, in summary, including the following three aspects: to start with, the productionaccelerated decline, crude oil and natural gas recovery efficiency is low, the effluence watercontent is increased, the development effect becomes poor; besides, the water injectiondevelopment of technical is more and more difficult in the low abundance and lowpermeability reservoir; thirdly, since is to develop potential and effective measures to reducegradually, cannot achieve calibration recovery efficiency, production cost rising year by year.In recent years, since the demand of crude oil is increased year by year, the carbondioxide injection technology is able to develop rapidly. Domestic carbon dioxide floodingtechnology research began in the1950s, after many years of accumulation of experience,which has improve the oil recovery ratio successfully in many fields.Aimed at the reservoir features of block X in L oil field, based on the mechanismanalysis of CO2oil-displacement, the author carried out experiments on CO2expansion andCO2Huff&Puff, meanwhile, field test was also carried out on the conclusion of labexperiments.Lab experiments provided effective data support and correct operation direction. Whilefiled tests proved and optimized the plan confirmed by lab experiments in development.After two rounds of work，aimed at the the special condition of block X，we confirmed，CO2injection increases the oil expandability, volume factor and gas/oil ratio, decreases thedensity and viscosity, and remarkably increases the elastic energy. As the viscosity declinesslightly, he main theory of CO2Huff and Puff. is oil expansion. The recovery efficiency in the1stcycle is good, and as the huff&puff cycle increases, recovery efficiency andoil-displacement ratio decreases obviously. When doing the huff&puff job at block Ou-37,we should control the injection amount in the range of0.15pore volume, take one cycle, andtake two cycles if too much oil left. At the same time, appropriate close time counts forenhancing recovery efficiency and oil-displacement ratio.To the reservoir condition and production situation, reasonable control of the CO2injection rate and injection parameters such as speed, shut-in time, can effectively improve theoil recovery, CO2Huff&Puff is well available, which is provided to be a good method andworth to spread.