Pressure Dynamic Analysis And Productivity Evaluation Of Staged Multi-clusters Fractured Horizontal Well In Tight Oil Reservoirs

Tight oil reservoir has the characters of low porosity,extra low permeability,complex pore structure and starting pressure gradient,which make it difficult to exploit.But with decreasing proportion of high quality reservoir,which has high porosity and permeability,in oil and gas resources,the development of conventional oil and gas shifts its focus to tight reservoirs and other unconventional oil and gas resources.The staged multi-clusters fracturing technology is the key in development of the tight oil reservoirs.And it has already achieved good development effect in Yanchang formation tight reservoir of Changqing Oilfield.Theoretical research and field practice show that staged multi-clusters fracturing technology can form a complex fracture network,get effective stimulation reservoir volume,improve the flow ability,and increase the production for formation.However,researches,especially about the influence of dynamic pressure,different reservoir and fracture parameters,for staged multi-clusters fractured in horizontal well are not enough.On the basis of dividing the flow phases of staged multi-clusters fractured in horizontal well,this study builds the mathematical model,uses the finite element method to calculate the flow model,and analyze the effects of different parameters on the dynamic pressure variation in horizontal well.Combined with domestic and international experience in the development of tight oil reservoir,numerical simulation method is used to do further study about well productivity for staged multiclusters fractured in horizontal well,analyze the effect of fracture half length,fracture conductivity,fracture density,and fracture shape on well productivity,and definite a reasonable range of those parameters for production.With those results,well patterns of joint injection and production,row distance and match degree between the fracture shape and well are optimized for staged multi-clusters fractured in horizontal wells.And the study also provides the theoretical guidance and decision for the efficient development of tight oil reservoirs.