电力振动器激振作用下的套管串振动特性

Vibration characteristics of casing string under the exciting force of an electric vibrator

振动固井是一种能够明显提高固井界面胶结强度的新方法,但推广使用该方法则需要解决水泥浆候凝阶段如何使固井管柱产生井下径向振动的问题。为此,研制了电力振动器。该振动器由高温电机振动组件把电能转化为机械能,电机振动组件通过输出轴带动偏心块旋转形成激振源,对套管串底部产生一个沿轴向方向旋转的激振力;然后运用主坐标分析法,分析激振力在直井套管串产生的振动特性,得出电力振动器振动对套管串产生的动响应模型;最后以某井井身结构设计为依据,分析了不同套管串长度、不同激振力和不同振动频率对套管串最下端的振动幅值的影响。研究结果表明:(1)套管串长度与套管串最下端的振动幅值呈反比关系;(2)激振力与套管串最下端的振动幅值呈正比关系;(3)振动频率的平方与套管串最下端的振动幅值呈反比关系。该研究成果可为在不同井深和不同振幅需求的固井现场应用振动固井技术提供理论支撑。

Vibration cementing is a new technique that can significantly improve the bond strength of cementing interface. To popularize this technique, it is necessary to solve the key problem of how to make cementing string generate downhole radial vibration in the cement coagulation stage. For this purpose, an electric vibrator was developed. With this vibrator, electric energy is converted into mechanical energy by means of a high-temperature motor vibration unit. The motor vibration unit rotates the eccentric block through an output shaft to generate an exciting source, which produces an axial-rotating exciting force at the bottom of the casing string. Then, the vibration characteristics of vertical well casing string under the exciting force were analyzed by using the principle coordinate analysis method, and the response model of casing string to an electric vibrator was developed. Finally, the effects of casing string length, exciting force and vibration frequency on the vibration amplitude at the lowermost of the casing string were analyzed based on a certain casing program. It is indicated that the casing string length and the square of vibration frequency are inversely proportional to the vibration amplitude at the lowermost of the casing string, and the exciting force is proportional to the vibration amplitude at the lowermost of the casing string. These research results provide a theoretical support for the application of vibration cementing technology to the cementing sites with different requirements on well depth and amplitude.