Innovations in Rotary Drill Bit Design to Reduce Vibration and Improve Durability
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Well drilling is an important process for extracting oil, natural gas, water, and mineral materials. Opening wells requires boring through earth formations, which can range from very soft to very hard. Penetrating into such formations requires specialized tools and operation procedures which should be employed based on the environment and application. Rotary drilling, in which a drill bit is used to crush the rock and penetrate into the formation, is one of the main methods of well drilling. Rotary cone bits are one of the main types of drill bits used for rotary drilling. There are two main problems encountered when drilling with rotary cone bits. Excessive vibration can cause damage to the entire system and can decrease efficiency of the drilling process. Failure of the bit’s bearings and seals can also result in damage to the bit and cessation of the drilling process. In recent years, a great deal of research has been undertaken to address these problems and find appropriate solutions to improve drilling efficiency and production rate while reducing the overall cost of drilling. In this thesis, a new design for rotary cone bits, with the objective of improving overall drilling performance, is presented. First, a new pattern for distribution of inserts over the cone is presented, which results in reduced vibration of the drillstring. Second a new design for the bit’s bearings is introduced that is capable of operating in harsh environments. Finally, an experimental set-up is introduced to evaluate the performance of the proposed designs.