Study On Drillability And Drill Bit Selection Of Complex Reservoirs In Fengcheng Formation Of Manan Slop

There are three types of large-scale reservoirs: sandy conglomerate,volcanic rock and dolomite in the Permian Fengcheng Formation reservoir in the south slope of Mahu sag,Xinjiang Oilfield.There are some problems in Fengcheng Formation in this area,such as large differences in longitudinal rock mechanical characteristics,difficult bit optimization and slow mechanical ROP,which need to be solved urgently.Therefore,this thesis studies the Formation Drillability Prediction,rock breaking mechanism and bit selection of Fengcheng Formation.On the basis of indoor core experiment,combined with logging data,based on single factor and multi factor data fitting regression method,through error analysis,the prediction model of rock drillability parameters suitable for Manan slope block is established,and the transverse and longitudinal distribution law of rock drillability parameters of Fengcheng Formation in this block is analyzed.According to the characteristics of Fengcheng Formation in Manan slope,the effects of bit structure parameters,cutting process parameters and rock mechanics parameters on rock breaking efficiency of cutting teeth are studied,and the characteristics of the interaction between PDC cutting teeth and formation rocks are analyzed.The results show that there is an optimal caster angle of cutting teeth;The rock breaking mechanism of axe shaped teeth,triangular teeth and other special-shaped teeth is significantly different from that of conventional teeth.Compared with conventional teeth,axe shaped teeth,triangular teeth and other special-shaped teeth have a large contact area with the rock and are easy to eat into the stratum.The rock breaking specific work of breaking the same volume of rock is lower,the rock breaking efficiency is higher,and the vibration amplitude of cutting force is smaller;The effects of different rock mechanical parameters on rock breaking efficiency are analyzed.According to the existing field well history data,the use of bits in Fengcheng Formation in Manan slope block is analyzed.Based on the grey clustering method and the use effect method,the drill bit is optimized.The results show that the drill bit models optimized by the two methods are basically the same.The practical application index and wear of the optimized bit are further analyzed,which shows that the above bit selection method is suitable for Manan slope block.