Research Of Theory And Techniques For Receiving Downward Control Codes In Rotary Steerable Drilling System

The research of the downward communication of the rotary steering drilling technology is the hot point to many oil-drilling companies and researchers in the whole world. The achievement of the research will promote the development of the rotary steering drilling technology.The direct purpose of downward communication research is to receive the downward control commands accurately from the ground, and that connected with the encoding method, decoding method and receiving device of the downward communication research. Ordinarily, downward communication uses the mud as the information transmission channel, and uses a variety of information receiver. The coding method, decoding method and the corresponding receiver has been proposed based on the underground rotor speed, the mud flow and the drill vibrations and so on. These technical methods have their own strengths but also has their disadvantages can not be eliminated.The research of receiving downward control codes starts with the encoding method of the downward communication, using the mud transmission channel is easier to connected with the WMD system and also for the drilling technology. Based on this, we use the inherent mud motor of the steering drilling tool to be the receiver on the principle of reducing the impact of actual drilling operations, we raised on encode of the duration of the pulse width generated from the three-descending and three-ascending of pulse of mud. For this to design the receiving device of downward control codes, in accordance with the requirement of safe and reliable, transmission efficiency, low bit error rate, to design the coding and the hardware and software systems of receiving device. The data collection part of the device detects the output voltage of the downhole motor, and the voltage has been compared. The core of the receiving device is detecting the signal threshold and timing the last time of pulse width, and it also has the strong anti-interference ability.Related test and measurement results show that the receiving device system to meet the requirements of downward communication, and it can correctly receive downward control commands from the ground.