Design And Implementation Of Communication While Drilling Instrument Based On CAN Bus

Measurement While Drilling(MWD)is a developing measurement technology,which can measure the parameters near the drill bit while drilling and upload them in real time.At present,MWD has become one of the main logging technologies in oil and gas exploration and production engineering.CAN bus is widely used in various industrial measurement fields.It is of great significance to use CAN bus as the field bus to construct the communication of measuring instruments while drilling.At present,the communication of downhole while drilling instruments in China mostly adopts RS485 bus,which uses master-slave architecture to construct the data transmission network of downhole instruments.The master equipment in the communication network makes inquiries to the slave equipment,and the slave equipment completes the real-time transmission of data in the way of reply,and the bus utilization rate is low.This dissertation mainly studies the communication and design of downhole MWD instrument.By analyzing the advantages of CAN bus compared with conventional field bus technology,it focuses on the construction of multi-parameter MWD measurement system using CAN bus as communication bus.Firstly,the communication function of the system is simulated by LabVIEW.In terms of hardware design,ds PIC33FJ128MC804 is selected as the master MCU,and the driving circuit of CAN node is designed,and the measuring circuit of temperature,pressure,bit pressure and torque is designed.Moreover,SPI bus and RS485 bus are used to design the storage and reading circuit of downhole data acquisition and working parameters.The measurement module is used as CAN node to form CAN communication network with MWD.Through reasonable downhole software design,the communication system of downhole measurement instrument is designed by using CAN bus.Finally,the communication system of measuring instrument while drilling based on CAN bus is tested in the laboratory.The experimental results show that the system can collect data in real time and accurately as expected,and can save the collected data through SPI bus and read it to the computer through RS485 bus interface,and achieve the design task and goal.This improves the reliability,stability and bus utilization of downhole measurement instrument communication.