| In the oil field exploration and development process, we often need to monitor the downhole tools posture, deviation angle and other parameters continuously and dynamically to master the downhole geological data, to enable more accurate drilling trajectory in accordance with the requirements of engineering design. And in the process, how to make the transmission of the data of downhole measurement effectively is critical to the success of recycling for oil and gas resources. Drilling data transfer rate is the bottleneck in the development of automation and intelligent of logging while drilling. So it is imminent for the development of new high speed data transmission technology. The purpose of the paper is to achieve the transmission of downhole data, and the use of orthogonal frequency division multiplexing (OFDM) technology for multi-carrier modulation acoustic signals to improve the efficiency of the system of communication.This paper starting with the characteristics of downhole data transmission channel-drillstring, and obtained its comb filter characteristics through modeling method. Combined with drilling noise characteristics and theoretical analysis of channel capacity, a program of OFDM data transmission system was proposed. This thesis uses MATLAB7.5for experimental platform, in combination with drilling system simulation mechanism of the acoustic transmission. And do some simulation analysis and contrast of the OFDM data transmission scheme.Through research of this subject, a set of OFDM data transmission system scheme was suggested, downhole data transmission on the research of new technology has some reference value. |
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