旋转导向钻井系统下行通讯接收功能的开发

在旋转导向钻井系统中，导向控制命令是由地面监控装置通过系统的下行通讯通道向井下导向工具发送。用钻井液负脉冲的方式传输下传信号，采取了三降三升为主要特点的命令字脉宽编码方式。地面命令发送装置将指令转换成一定脉宽的钻井液排量变化，用5位指令码表示相应的导向力级别和工具面角。在井下导向工具中设计了下行通讯接收装置。由装置的数据采集部分检测反映钻井液脉冲变化的井下泥浆电机的输出电压或频率，经数据处理和解释，以信号阈值判断和脉宽识别为核心，由5个指令码的脉冲宽度时间和顺序计算得到正确的下传导向命令字。为了提高下行信号传输的可靠性和抗干扰能力，在接收装置的硬件和软件中采用了相应的措施。试验结果证明了这种下行通讯方案的可行性。

Development of downward communication receiving function in rotary steerable drilling system

In the rotary steerable drilling system, there is a downward communication channel to send the guidance control command from the ground monitor to the down-hole steering tool. The negative pulse of drilling fluid transmits a downward command mode encoded by the three-descending and three-ascending words. A command-sending device on the ground transmits the command mode into flow rate of drilling fluid, which is changing with a certain pulse width of drilling fluid. A control word composed of five instruction codes represents the grade of guiding force and angle of tool face. There is a downward receiving device in the down-hole steering tool. The data acquisition unit of the device can detect the output voltage or frequency of the down-hole fluid motor that reflects the pulse flow change of drilling fluid. The data processing and interpretation software based on signal threshold judgment and pulse width identification can process the received information. Then a right guiding control command calculated using the pulse width and the sequence of the 5 codes could be obtained. Several different measures were used in the receiving device for improving the reliability and anti-interference performance of downward signal transmission. Experimental results showed the feasibility of this downward transmission scheme.