邻井距离随钻电磁探测系统的设计与实现

Design and Implementation of Electromagnetic Detection System for Distance of Adjacent Wells

摘要:

邻井距离随钻探测是精细控制复杂结构井井眼轨迹的关键技术之一;基于旋转磁场测距原理,研制了邻井距离随钻电磁探测系统;该系统以安装在钻头后方的磁短节作为交变磁场发生器,位于邻井中的三轴磁场传感器作为信号接收器;针对磁场信号低频微弱特性,研制了低噪声、窄通频带、高精度数据采集电路；采用改进的DFT谱峰法,自动跟踪锁定井下三轴磁场信号,滤除其它频率的杂波和噪声,精确提取出信号的幅值；采用曼码通信将井下数据传至地面仪,地面仪据此计算出邻井之间的距离和方位,引导钻进作业;室外测试和现场试验表明,所研制的邻井距离探测系统,最大有效测距距离可达50 m,可以满足SAGD双水平井和煤层气连通井的钻井工程实际需求。

Abstract:

Adjacent wells distance measurement while drilling is one of the key technologies to fine-grained control of complex structures wellbore trajectory. Based on the principle of rotating magnet ranging,an electromagnetic adjacent well detection system while drilling is developed. A magnetic short section is designed and installed behind the drill bit to generate the alternating magnetic field,a tri-axial magnetic field sensor is located in the adjacent well as a signal receiver,and a low-noise,narrow pass band,high-precision data acquisition circuit is developed to detect the weak low-frequency magnetic field signal. A filtering method based on the modified DFT peak spectrum value is proposed to track the alternating magnetic frequency accuratly and extract the magnetic amplitude precisely. The Manchester code communication is used to transmit the downhole data to the surface instrument. The surface instrument calculates the distance and orientation between adjacent wells and guides drilling operations. The outdoor and field tests showed that the maximum measurement distance range of the developed system is up to 50 meters,which can meet the actual demand of drilling engineering.