Study on downhole vibration measurement and analysis theory

In order to understand the complicated vibration of drill bit and drill string system, to analyze the dynamic performance of downhole tools, and to avoid damage by abnormal vibration, it is necessary to develop a set of vibration measurement tool for downhole environment. By establishing the kinetic and analytic model of multi-coordinate axis, a dynamic equation and a measurement equation were established respectively which proved that a 3-axis accelerometer is able to measure and analyze various vibration of the system. And a set of methods to judge and analyze abnormal vibration were deduced, such as bit bounce, stick-slip, lateral vibration (shock), and whirl. The analytic results provided strong theoretic support for the research and development of downhole vibration measurement tool and downhole vibration analysis.