The Research Of Wireless Transmission Of Drilling-information

The rate of the existing mud pulse telemetry techniques can’t satisfy the demand of modern LWD(Logging While Drilling). A kind of wireless data transmission method, which employs acoustic waves via the wall of the drill-string to transmit the downhole parameters to the surface, can bring significant cost saving and increased reliability.The acoustic dispersion properties and transient analysis of the periodic structure is simulated, and the results display that the drill-string acts as a comb-filter. The obstacle of the communication exists in the fading and time delay.According to the specialty of LWD, the system scheme are designed, which consist of the downhole transmission section, including data acquisition, coding, transmission, and the surface system, including signal front-end processing, detection, store, communication with PC. The PCB and control flows are accomplished.On the basis of simulation of high-voltage and powerful pulse discharge technique, a2ASK method is put forward, which the magnetostrictive material is driven by the discharging of a storage capacitor when "1" of binary system is transmitted. In the surface system, the signal quality is enhanced by an improved stepper gain control with a signal peak judgment.An experimental system with the rate of20bps is designed to test, and the results show this technique has a bright prospect.