Study On Ultrasonic Signal Coding Of Near-bit Measurement And Interface With MWD

The work in this paper is a part of the research work"The research of technology of measurement of inclination near bit",which is funded by China Petroleum & Chemical Corporation (Sinopec).It is mainly about the realizing of delivering inclination from near bit to MWD,which is above the positive displacement motor through ultrasonic.The paper has discussed the existing status and progress in terms of measurement near bit while drilling in both home and abroad in detail,puts forward ultrasonic signal modem pointed to the rule of ultrasonic transmission and the problems down hole, and then proved that there exits remarkable advantages in real-time measurement of inclination. This paper has also probed into the designs of down hole signal transmission system,whose core is single-chip microcomputer,ananyzed many particular problem existing in down hole real-time condition such as dramatic viberations,high temperatures,noises,narrow spaces,limited energies,and done much significant research in hardware and software designs in single-chip microcomputer controlled systems in view of the issues above.Finally,the paper has made specific introduction to the hardware layout in single-chip microcomputer system and series communication and made necessary statements to relevant software realization as well.Signal deliver experiments have been put on the system in door, and then the range of ultrasonic frequency has been defined,the best frequency has been defined at last.The best one bit last time has been forwardly defined by experiments in door.The digital signal deliver velocity is at 1000Bit/s.