| The drilling technology has changed from “geometric guidance” characterized by “open loop control” to “geo-oriented” characterized by “closed loop control” recently,which result in more and more data needs to be uploaded from the underground in real time.But the existing data transmission technology while drilling can't meet the requirements.The problem of highspeed data transmission while drilling has been tried to solve in this thesis based on underwater acoustic communication technology.The main works include three aspects,they are theoretical research,simulation analysis and experimental testing.Firstly,the development history of data transmission technology while drilling was introduced.The research status of existing technology was summarized.The principle and comparative advantages of acoustic data transmission technology based on drilling fluid were analyzed.Secondly,the overall scheme of the acoustic data transmission system based on drilling fluid was determined.The feasibility of the scheme was analyzed.The effects of sound velocity,frequency,drilling fluid viscosity and other factors on acoustic transmission were discussed in detail.Thirdly,according to the basic structure of communication system,the characteristics of acoustic source,channel and sink while drilling were analyzed by the finite element simulation.The emission characteristics of the longitudinal vibration transducer at different frequencies in the drilling fluid of the drill pipe were studied.The emission performance of the transducer in the pipeline and open water was compared.The effects of acoustic frequency,drilling fluid viscosity,drill pipe diameter reduction and bending on acoustic transmission were studied.Finally,the effect of the characteristics of the receiving transducer on the acoustic data transmission system was analyzed.Fourthly,the acoustic data transmission experimental system has been set up,which include the buffer circuit,isolation circuit,power amplifier circuit,pulse transformer and transducer impedance matching circuit of the transmitting driver module,preamplifier circuit and bandpass filter circuit of the receiving module,etc.NI Labview has been selected for data acquisition and signal processing.Finally,the experimental research on acoustic transmission has been carried out,which include the emission performance comparison experiment,transmission attenuation experiment,drill pipe reduction experiment and hydraulic circulation experiment of acoustic wave data transmission.The results show that the designed experimental system can be operated stably.The experimental results are basically consistent with theoretical research and simulation analysis.The feasibility of the acoustic data transmission technology based on drilling fluid is verified,which lays a good foundation for further research. |
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