绳索取心近钻头随钻测量系统设计与试验

Design of a near-bit downhole measurement system wlile drilling for wireline coring

摘要:

传统的随钻测量方法应用于取心钻探时，受限于岩心管对泥浆脉冲传输通道的堵塞，随钻仪器安装于取心钻具后方，导致测量仪器与钻头之间存在较大距离，造成测量的轨迹及工况数据存在滞后性，影响钻探工艺及轨迹的精确控制。针对此问题，提出了适用于绳索取心的近钻头随钻测量系统，利用近钻头发射端实时采集工况及轨迹数据，采集到的数据经甚低频电磁波发送到与取心钻具内管总成相连接的接收端进行存储，待取心完毕打捞岩心管时将仪器提出进行数据读取。介绍了系统的整体方案及电路设计，开展了系统短传功能的室内验证试验，试验结果表明系统可在井下进行跨取心钻具的近钻头信息传输，且无线短传距离可达8 m。研究成果可为近钻头随钻测量系统的相关研究提供借鉴。

关键词:绳索取心钻具;近钻头随钻测量;甚低频电磁波;无线短传

Abstract:

When applied to core drilling， the traditional measurement methods while drilling are limited by the blockage of the mud pulse transmission channel by the core barrel. The measurement instrument are installed behind the core drilling assembly， resulting in a large distance between the instrument and the bit， which leads to significant lag in trajectory and operating condition data， and thereforea affects the precise control of drilling process and trajectory. A near-bit measurement system while drilling for wireline coring is proposed to address this issue. The system utilizes a near-bit transmitting unit to collect operating conditions and trajectory data in real time. The collected data is transmitted via very low frequency electromagnetic waves to be stored in a receiving unit connected to the core drilling assembly’s inner tube. After core extraction， the instrument is lifted along with the core barrel for data retrieval. This paper introduces the system’s overall scheme and circuit design， moreover， experiments for short-range transmission function are carried out. The results demonstrate that the system can achieve near-bit information transmission across the core drilling assembly downhole， with a wireless transmission distance of up to 8m. These research findings can serve as a reference for researchers in the field of near-bit measurement system while drilling.

Key words:wireline core drilling;near-bit measurement while drilling;very low frequency electromagnetic waves;wireless short-range transmission