Study On Rapid Sampling And Storage Technology Of Near-Bit Vibration Signal

Guided drilling is a crucial automated technique that controls the wellbore trajectory to drill to the target formation.Accurate measurement of tool attitude is the key to perform accurate guidance control.However,the near-bit vibration not only generates the attitude measurement error,but also may lead to failure of measurement.Therefore,it is necessary to study the near-bit vibration regularity,and then deal with the tool attitude dynamic measurement problem.The development of a near-bit vibration signal collection system,which satisfies the requirements of measurement while drilling,rapid collection,and large-capacity storage to obtain a large amount of near-bit vibration information,is a prerequisite to handle tool attitude dynamic measurement.The main work and results of this article are as follows:Firstly,the technical problems of near-bit vibration signal acquisition are studied.The downhole signal characteristics are analyzed.The overall technical scheme is proposed,and the corresponding structure,composition and working principle of the system are given;Secondly,the rapid sampling and storage of multi-sensor signals are studied with low operating frequency of the microprocessor.The multi-parameter serial rapid sampling method,and the rapid intermediate buffering and full page writing are proposed for timing long analog-to-digital conversion and DMA buffering.We propose a storage method based on the dsPIC33FJ128MC804 digital signal controller and the optimized memory device,complete the design and debugging of main circuits such as system power supply,signal conditioning,peripheral interface,and memory interface,and develop the corresponding functional software;Finally,the problem of ground reading and data playback of near-bit vibration data is studied.Data playback software is designed with serial communication,data processing,waveform display and data storage.System tests show that downhole sampling and data storage devices can operate with temperature up to 105°C and 2 GB storage capacity,and could collect and record 120 hours of data at a storage frequency of more than 300 data terms per second.These research work and achievements can be applied to practice to obtain near-bit vibration information,to study near-bit vibration rules and to solve dynamic measurement problems of tool attitude.