智能导钻井下随钻单芯总线信道特征及接口驱动

随钻总线系统实时收集上传井下随钻测井数据与钻井工程参数以及下达地面控制命令，通过井地传输系统，实现地面与井下之间的数据与命令交换，形成钻井控制大闭环，是完成智能导钻的关键技术环节.本文从随钻单芯总线的信道特征、总线电路及其等效模型几方面介绍智能导钻井下随钻单芯总线系统，总结了总线的最佳工作频率及负载特征，分析了总线接口的简单可靠的驱动方法，通过电路测试，验证其可靠性.研究发现单芯总线信道的特征阻抗随分布参数变化很大，导致仪器横卧与竖立状态下，通信信道特性明显不同，本文根据信道特性变化规律，避开敏感频带，并将信道特征转换成等效电路模型，进一步明确了总线系统正常工作的参数设置方法.设计的总线系统已开展井下实钻试验连续工作3口井，累计工作时间超过270 h，累计钻进5300 m以上，未发现故障，系统工作稳定.

Channel characteristics and interface drive of single core bus of while drilling in intelligent guide drilling

The Logging While Drilling (LWD) bus collects and uploads downhole logging data and drilling engineering parameters in real time as well as downloads ground control commands. Through the telemetry system, data and commands transmission between the surface and downhole can be realized and helps to form the drilling control, which is the key technical point to complete the intelligent drilling. This paper introduces the LWD bus system in intelligent drilling from the aspects of channel characteristics, bus circuit and its equivalent model, summarizes the optimal operating frequency and load characteristics of the bus, analyzes the simple and reliable driving method of the bus interface, and verifies its reliability through circuit testing. It is found that the characteristic impedance of the single-core bus channel varies greatly with the distribution parameters, which leads to the obvious difference in the communication channel characteristics between the instrument lying down and the instrument standing up. In this paper, according to the change rule of the channel characteristics, the sensitive frequency band is avoided, and the channel characteristics are converted into the equivalent circuit model, and the parameter setting method for the normal operation of the bus system is further defined. The designed system, which has carried out the downhole real drilling test for 3 wells in a row, worked stably with more than 270 hours cumulative working time and 5300 m total drilling in no fault.