空气钻井中钻柱扭转振动的计算

空气钻井是指钻进过程中循环介质为空气的钻井。空气钻井有利于提高钻井速度,缩短建井周期,降低钻井总成本;能很好的保护产层,但其处理地层出水的能力差;井壁不稳定;井底欠压值太大,处于无控制的欠平衡状态,导致储层速敏、出砂,甚至坍塌;钻具失效问题严重。本文在理论分析的基础上,对各种振动进行了较好的数值分析。研究表明,整体钻柱的扭转振动特性受钻柱规格以及长度影响。长度增加,钻柱相应各阶固有频率显著降低。计入钻井液附加质量效应后,钻柱的各阶固有频率显著降低。分析表明,钻井液阻尼对钻柱动力安全性有一定的积极意义。

Calculation of the Drill String Lateral Vibration in the Air Drilling

Air Drilling is defined that cycle Medium is air in the process of drilling.Air Drilling will help improving the speed of drilling,shorting the period of construction,lowing total cost of drilling,and can protect producing horizon well,but the ability of the treatment of outing water is poor;the wall of well is instable;the under voltage is value too in the bottom of well,is in the uncontrolled under-balanced state,leading reservoir velocity sensitivity and sand or even collapse.The problem of BHA’s failure is serious.Based on theory study,detailed numerical simulation on properties of the drill string was done in this paper.The results show that the property of rotary vibration changes while the string dimension and the length of drill string change.Due to the influence of the drilling fluid the natural frequency becomes lower.Analysis shows that drilling fluid damper have a certain positive significance on the drill string security.