Characterization of Vibration Pattern and Axial Vibration in Ultra-deep Straight Wells

Abstract

With the development of oil and gas exploration to ultra-deep and extra-deep fields, the drilling depth increases year by year, and the downhole drilling column exhibits extremely complex dynamics under uncertain loading and environmental conditions downhole, which directly affects the drilling efficiency and safety. Drilling accidents such as wear and fatigue failure of the drill pipe caused by axial vibration result in direct economic losses and increase additional drilling costs. Therefore, in this paper, a well body structure in Sichuan Shuangyuishi block is selected as the research object, and a whole-well drilling column dynamic model is established to calculate the axial vibration characteristics and vibration patterns. The results show that: the larger drilling pressure makes the transverse vibration vibration node sink, and the stability of the drilling tool decreases; the frequency of the drill pipe increases with the increase of the stiffness, and increases with the decrease of the drilling pressure; the trend of axial force reduction from the wellhead to the drilling tool combination is relatively smooth, and the change amplitude is relatively small, and the trend of the axial force reduction is obviously intensified after entering into the drilling tool combination; at the position of the wellhead, the beating amplitude of the node of the drilling column is relatively large However, the vibration frequency is lower compared with the lower BHA; the vibration intensity becomes more and more intense from the top to the bottom.