| The rotary steerable drilling technology by downlink information transfer is one of the key technologies to achieve closed-loop control of wellbore trajectory, The instructions compiled by the upper wellhead downlink information transmission device are transferred to downhole, though the negative mud pressure pulse. To communicate the ground and the tools which underground, and control downhole drilling tool operations gesture. Researching on this technology could help break the monopoly of foreign companies, and achieve technology localization of drilling downlink information transmission.The main contents include the program design of rotary steerable drilling downward information transmission technology, development of computer-controlled drilling downlink information transmission device, selection of filtering and encoding methods, and the experimental research on downstream information transmission device. Finally, a devices which apply to the rotary steerable drilling downlink information transmission technology has be developed. This devices includes ground command generation system, downhole information receiving system, and the development of associated ground control software which optimizing the encoding and decoding systems. Taking into account the performance of low-power and high temperature and pressure, the downhole pressure had been tested by pressure sensor with non-pressure transmission hole, and eliminates the noise of mud medium.The technology of the rotary steerable drilling downlink information transmission is achieved by the negative mud pressure pulse. This system has structure of simple and high reliability. The three downlink test shows that the communication system work well and meet the actual needs of the rotary steerable drilling. This system was used in "863" project, and meet the requirement of rotary steerable drilling. |
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