Optimize Method of Drilling Parameter of Compound Drilling Based on Mechanical Specific Energy Theory

With the drilling targets going increasingly deeper,a new drilling parameters optimization method based on mechanical specific energy(MSE)theory was investigated to continually improve the rate of penetration in deep formations.From the perspectives of rock mechanics and conservation of energy,the relationship between drilling parameters and ROP has been derived from comprehensive analysis of optimized drilling mechanism based on MSE.Based on the R.Teale MSE model,by introducing the sliding friction coefficient and rock-broken efficiency of the bit,the torque was expressed as the function of drilling weight to solve the difficulty of measuring torque directly in conventional drilling,the optimized models were built on the basis of specific energy theory for different drilling modes,and a real-time drilling optimization system was developed.The system can monitor all dynamic drilling parameters during drilling operation,and feed back the performance of drilling parameters and downhole situation in real time.A pilot test shows the average ROP increased by 20% to 30% compared with offset wells,and prolonged the service life of bit.The research results indicate that specific energy optimized drilling technique can optimize drilling parameters in real time,which can be used to drilling design,parameter optimization and analysis,so as to raise the ROP in deep formations and reduce drilling cost.