钻柱—钻头—岩石系统动态行为仿真

COMPUTER SIMULATION ON DYNAMIC ACTION OF DRILLSTRING-BIT-ROCK SYSTEM

利用单齿压入与刮切岩石实验建立了钻头与岩石互作用力学模型 ,实现了对钻头在钻井过程中工作行为的仿真计算 ;建立了基于研究钻柱—钻头—岩石系统动态行为的动力学模型 ,可以对钻井过程中钻压、扭矩、转速等参数的动态变化过程进行计算机仿真研究。从仿真结果可以看出 ,钻头在钻井过程中由于牙齿在井底的交替吃入以及井底本身的凹凸不平造成钻头在井底的纵向振动 ,其钻压的振幅一般为平均钻压的 30 %左右 ;同时 ,由于钻头在井底的刮切作用造成了钻头转速以及扭矩的变化 ,转速的变化相对来说较为平缓。该动力学模型能较好的描述钻柱—钻头—岩石系统的动态行为 。

The main work of the research in this paper is as follows:the interaction model of bit and rock is established which was based on the experiment of interaction between single tooth and rock.It is a good fundament for the computer simulation on working action of rock bit drilling.Setting up dynamic model to research the dynamic action of drillingstring bit rock system.In the dynamic action simulation of drillstring bit rock,based on the geometry model and kinematics model of roller cone rock bit,and the model of interaction between rock bit and rock,the dynamic models of drillstring and rock bit are established.Thereby we can calculate WOB,torque,rotate speed and so no.The follow conclusions can be obtained:The vibration of rock bit is caused by the interaction between rock bit and rock,and the swing of WOB is about 30% of the average.The change of rotate speed and torque are caused by the scraping of rock bit.The change of rotate speed is smooth.The swing of torque on bit and on the top is about 50% of the average.According to the above conclusions,we can say that the dynamic models can express the dynamic action of drillstring bit rock clearly.It is instructive to design new rock bit and study drilling mechanics.