The Research Of Fractured-vuggy Reservoir Waterflood Recovery Mechanism

Fractured-vuggy carbonate reservoir is well known for strong anisotropy,heterogeneity and multi-scale property,where pore structure is very complex.Therefore the rule of fluid flow in fractured-vuggy carbonate reservoir is different from that in the regular reservoir.Carrying out the research on the water injection exploitation mechanism of fractured-vuggy carbonate reservoir has important significance for the efficient exploitation of such reservoirs.In this paper,the water injection exploitation mechanism of fractured-vuggy carbonate reservoir is studied from the physical simulation,numerical simulation and theoretical analysis.First,a complex and serialized fractured-vuggy network model has been designed according to the similarity criterion which ranges from single simple cave to complex three-dimensional fractured-vuggy network model,which converts the site injection and exploitation parameters into indoor physical simulation experiment parameters and which studies the water-flooding mechanism of fractured-vuggy media(different fractured-vuggy combination)under different types of filling and filling degree;Under different development constraints(well pattern,injection production method,strength,etc.),the water breakthrough,water injection and its law as well as the remaining oil distribution of the fractured-vuggy are studied.Then,the numerical simulation experiment research for the unique fractured-vuggy is carried out and the numerical simulation experiment method based on the combination with physical simulation results is verified and perfected.Through numerical simulation,the scope of research has been extended,that is,the production characteristics(change in oil production and moisture content,etc.)and the distribution of remaining oil under different fractured-vuggy and the impact of different well pattern,injection exploitation method and strength on production characteristics are studied to reveal the water injection exploitation mechanism of fractured-vuggy and to put forward the corresponding measures to improve development effect.Finally,the similarity criterion equation and dimensionless numbers are derived for different fractured-vuggy and exploitation methods based on derivation principle of similarity criterion.In this paper,the mechanism and influencing factors of fractured-vuggy reservoir water injection exploitation have been revealed through the mechanics mechanism in the quantitative analysis of dimensionless exploitation numbers which provides theoretical support for scientific water injection and exploitation of the fractured-vuggy carbonate reservoir.