钻井流体粘度对钻柱纵向振动的影响

针对气体钻井技术在低压油气田开发中出现气体钻井的钻柱振动和钻具破坏的问题，概述了气体钻井面临的钻柱振动问题、钻具破坏问题和解决问题的途径。介绍了位移激励法的钻柱纵向振动分析的数学模型和力学分析软件。对钻井流体粘度对钻柱纵向振动的影响规律进行了研究。数据表明,钻井流体的粘度对钻柱的纵向振动影响较大。在一般情况下, 钻井流体的粘度越小, 钻柱的振动幅度越大。钻井流体的粘度对钻柱振动的共振频率影响不大。气体钻井虽然提高了钻进速度，但同时也对钻具防破坏技术提出了更高的要求。

Influence of Drilling Fluid Viscosity on Drill String Longitudinal Vibration

Gas drilling is of great use in the development of low pressure oil-gas fields. Gas drilling can increase drilling rate and protect production formation effectively. However, it is found in practice that drill string vibration and drill tools failure are severe problems in gas drilling. In this paper, the drill string vibration and failure problems found in gas drilling and the ways to solve them are introduced, mathematical models of longitudinal vibration of drill string induced by bit displacement and mechanical analysis software presented, influence of drilling fluid viscosity on drill string longitudinal vibration studied. Calculation indicates that drilling fluid viscosity is of great influence on drill string longitudinal vibration. Drill string longitudinal vibration increases as drilling fluid viscosity decreases. The influence of drilling fluid viscosity on resonant frequency is little. Although gas drilling increases penetration rate, it needs more advanced technology to prevent drill string from failure.