Experiment And Theoretical Study On Improving Water Displacement Efficiency Of Sandstone Reservoir

The world's oil is mainly distributed in sandstone,while China's oil is mainly distributed in the sedimentary oil-producing environment dominated by continental strata,most of which are sandstone reservoirs,accounting for more than 90%,and most of the development methods are water injection development.The water flooding efficiency of sandstone reservoirs is an important parameter for evaluating reservoir development effects,performing reservoir dynamic analysis and determining the distribution of residual oil in water flooding.The research on the water flooding efficiency of sandstone reservoirs is of great significance for the rational development of oil reservoirs.Therefore,it is necessary to strengthen the basic theoretical research on oil displacement efficiency by means of indoor water flooding experiments.The paper uses laboratory experiments as the main research method.Through a combination of statistical analysis and theoretical demonstration of a large number of experimental data,the sandstone reservoir permeability,rock wettability,injection velocity,injection pore volume multiple(PV number),microscopic pores are established.The relationship between structure and fluid properties and oil displacement efficiency;comprehensively considering the influence of single factor,the prediction model of core water flooding efficiency of Kong 2 Member of Dagang Oilfield and the prediction model of water flooding efficiency of low permeability sand filling model were established.The method of improving the efficiency of water flooding is demonstrated and demonstrated.The results show that the oil displacement efficiency and permeability of low permeability reservoirs show a good positive correlation.The higher the permeability,the higher the oil displacement efficiency,the relationship between oil displacement efficiency and permeability in medium and high permeability reservoirs is not obvious.The efficiency of flooding in hydrophilic reservoirs is generally higher than that in oleophilic reservoirs,the relationship between oil displacement efficiency and injection speed is not a simple positive correlation.The injection speed is not as fast as possible,but there is an optimal one.The injection speed;the oil displacement efficiency has a good positive correlation with the logarithm of the injection pore volume multiple(PV number),and the overall trend is “first fast and then slow”,the better the microscopic pore structure,the higher the oil displacement efficiency.Due to the action of capillary force,fingering phenomenon and flow around and obstruction,the remaining oil distribution is mainly divided into 6 kinds of residual oils such as film-like,horn-like,ramp-like,cluster-like,inter-granular and intergranular adsorption.Mode,water flooding efficiency can be improved by hydrodynamic methods,chemical flooding,sedimentary microfacies guidance,and water shutoff profile control measures.With the increasing difficulty in the development of high water cut period of sandstone reservoirs,the research on the factors affecting the efficiency of oil displacement,the research on the distribution characteristics and mechanism of remaining oil,and the research on the potential of remaining oil are becoming more and more urgent.The potential of Tibet and the remaining oil potential provide a theoretical basis.