Study On High-efficiency Rock-breaking Technology In Igneous Rock Drilling At Songnan Gas Field

The deep igneous rock resources in Songnan gas field have great development potential and deep burial depth,but the mechanical penetration rate and the bit footage are low.Therefore,it is necessary to carry out efficient rock breaking technology research in igneous formation drilling.Based on geological research,this paper analyzes the lithologic characteristics of igneous rocks,and draws the conclusion that the igneous rocks in this area have strong abrasiveness and poor drillability through a large number of indoor bench tests.The measured compressive strength of igneous rocks in this area is more than 300 mpa,and the average drillability grade has exceeded grade 10.According to the drilling practice in this area in recent years,this paper summarizes and analyzes the application of the four most commonly used rock breaking methods in the field.PDC + screw combination is selected as the most effective rock breaking method with development potential by using bit effect index method.According to the failure analysis of PDC bit,this paper studies the personalized design and application of new PDC bit.Through the research and application analysis of bit cutting teeth,profile shape,cutting structure,diameter protection design and hydraulic structure,combined with the change of screw head number,centralizer size and optimization of BHA,the research results are applied in two wells in recent construction.The rock breaking effect is very good.Finally,it is concluded that the personalized PDC bit with its own Φ210mm centralizer,medium speed-high torque screw and Φ212mm under size centralizer constitutes a double stable leveling BHA.The composite drilling section accounts for a high proportion,the average ROP reaches more than 3m/h,and the single footage reaches more than 145 m,forming a set of "personalized PDC bit + medium speed-high torque screw combination" drilling speed increase technology.