Research On Rock Breaking Mechanism And Design Of Composite Drill Bit

The drill bit as a major rock-breaking tool in oil drilling works,its design is good or bad Largely affected the drilling costs and drilling efficiency.Commonly used drill bits are PDC bits and roller bits.However,with the rapid reduction of shallow oil,drilling began to face more and more complex formation,deep wells,ultra-deep wells,difficult to drill formation.so the design and use of the drill also put forward higher requirements.In recent years,with the successful application of PDC-cone composite drill bits in foreign drilling sites,the excellent drilling data obtained have identified a certain path for the development of drill bits.For the domestic,some manufacturers of drill bit are also eager to get high-performance and practical composite drill,breaking the foreign technology monopoly,to establish their own composite drill manufacturing technology and systems.At present,PDC-cone composite drill bit has the advantages of high drilling efficiency,long slope setting and long drilling life in hard stratum,dense stratum,high abrasive formation and directional drilling as a new rock breaking tool.Although some research has been done on the composite drill bit and some research results have also been made.However,the mechanism and design method of the composite drill bit need to be in-depth studied and perfected.To this end,this paper for the composite drill carried out the following research,which including:1、Study on the cone kinematics of the compound bit,and the influence of the Outline of cone on the wheel speed ratio is discussed.2、Aiming at the rock breaking characteristics of the composite bit,the simulation analysis of the rock breaking mechanism of the composite bit was carried out.In the case of PDC tooth inclination angle of 15°,20°and 25° respectively,the tooth pit shape formed by the broken rock of the three kinds of tooth teeth under different invasion depth was studied.The damage range of the rock Consumption of the composite drill bit.3、According to the simulation analysis,the vertical press force and the Slip scraping force model of the dental tooth are established,and the energy consumption of the pulverized rock of the composite bit is calculated.Aiming at the pre-damage rock breaking of the teeth of the tooth,the rock breaking process of the PDC cutting tooth was analyzed in detail,and the energy consumption of the PDC tooth cutting and cutting rock was calculated.4、The design principle of the two sets of cutting structure,the outline of the cone,the tooth profile,the contour of the crown,the design of gauge structure are put forward.The individual design of compound bit is discussed for the hard stratum,the heterogeneous stratum and the directional drilling.5、According to the wellbore structure and the formation characteristics in Renyel oil field,the composite bit product was designed and the field test was carried out to verify the advantages of the composite drill bit in the difficult drilling area.In this paper,we aim to carry out the simulation analysis of the rock breaking mechanism of the composite bit,start from the pre-damage of the rock of the tooth teeth,study the cutting force change and the work power of the PDC cutting tooth,establish two sets of cutting structure work size model,and explore two sets of cutting structure And the design method of compound bit is discussed,which can provide reference for individual design and field application of compound bit.