Research On Rock Crushing Mechanism Of PDC Drill Bits Based On Deep Reservoir Of Songliao Basin

With the demand of oil and gas resources increase,the process of oil and gas exploration and exploitation is deepening,the difficulty of exploration is increasing,and the depth of drilling extends from shallow to deep,deep to extra deep.The Songliao Basin has two sets of oil and gas assemblages,with medium shallow strata and deep strata.The medium shallow layers are mainly oil-producing,while deep layers are mainly gas-producing.However,the deep strata of the Songliao Basin are complex.Conventional cone bit has a low drilling speed.The PDC drill bits has high hardness and high abrasion resistance,with the rock breaking efficiency,drilling speed,long life,stable,it’s comprehensive economic benefits significantly.Therefore,it is very important to improve the mechanical rigidity of the deep stratigraphic PDC bit by studying the nature of deep rock mechanics,and it is very important to improve the drilling speed of the deep strata of Songliao.In this paper,the relationship between the PDC cutting teeth and the rock is clarified by studying the rock breaking mechanism,and the phenomenon of stick-slip vibration of the PDC drill bits in the deep stratum drilling process is revealed,which provides guidance for the application of PDC drill bits in deep layer of Songliao.In this paper,the theoretical research and indoor test method are used to study the mechanism of PDC drill bit breaking rock.The details are as follows:(1)The characteristics of the deep drilling in the Songliao Basin are analyzed.The mechanical properties of the rock in the deep strata of Songliao are studied by means of laboratory tests.The effects of different lithologic rock samples are tested by uniaxial,triaxial compression experiments.Stress-strain curve,the deformation parameters and strength parameters such as compressive strength,elastic modulus,Poisson’s ratio,cohesion and internal friction angle are calculated.(2)The rock breaking characteristics of PDC bit are analyzed.According to the relationship between PDC tooth and rock interaction,the mechanical model of PDC tooth intrusion rock under the bottomhole condition is established,and the conditions of rock breaking in PDC tooth press and cutting are obtained.(3)The PDC cutting torque model of the drill bit is established,and the influence factors of the cutting torque of the drill bit are analyzed according to the mechanical properties of the deep rock of Songliao basin.(4)According to the kinematic characteristics of the drill string,the mechanical model of the drill string slippery vibration is established.Based on the actual drilling parameters of the Xu Shen 7 well,the influence factors of the slippery vibration of the deep drilling are analyzed.