The Applied Research And Data Acquisition Of Drilling String Vibration Signals

In recent years, because of the ever increasing premature failures of drilling tools,drilling cost has raised. Advanced development demonstrate that drilling string vibration is acommon phenomenon in the well during drilling and high amplitude vibration of the drillingstring often is the main reason for failure of the drilling tools. So, studies of drilling stringvibration are more and more important for people now. Drilling string vibration signalscontain very full and complex vibration waves, it include the vibration of the drilling stringand bit by themselves, the vibration stimulated by the interaction of bit and the formation, thevibration induced by colliding between drill string and borehole and vibration caused bystick-slip. It can be divided into three kinds of vibration: longitudinal vibration, transversevibration and torsion vibration. Feature of drilling string vibration have relationship withdrilling tool structure, motion response, strain and so on. Therefore, studies of the drillingstring vibration signals have important significance for the control of the drilling stringvibration, accident prevention of drilling string, judging the condition in down hole andoptimized drilling technology.This paper has learned the drilling string vibration mechanism and signal feature in thefirst. On the basis of the interior and foreign research, through optimization of vibrationtransducer and development of equipment keeper, we have developed a set of aground systemto acquire vibration signals of the drilling string which is approved for acquisition of drillingstring vibration signals. Then this paper researches processing methods of drilling stringvibration signals in time domain and frequency domain, develops corresponding processingsoftware for the drilling string vibration signals and take a field test for the software with along time. At the same time, the paper acquire drilling string vibration signals in differentdrilling string combinations, different drilling parameters, different conditions and different lithology, we have found drilling string vibration signals effected by different drillingparameters, gained the downhole drilling string vibration signal features when bit jumping,stick-slip and when drilling sandstone, cleaving stone and conglomerate.Field experiments demonstrate that different condition has different signals,complexcondition effect low- frequency and different layer effect high-frequency.Drilling stringvibration signals can reflect work condition of drilling tools, the studies are beneficial forrecognizing premature failures and decreasing drilling cost price.