Abstract:

As traditional measurement-while-drilling (MWD) techniques can not meet the high-precision guidance requirement of complex structure wells, such as horizontal intersection wells and steam assisted gravity drainage (SAGD) parallel wells in heavy oil development, the present paper proposed a high-precision guidance method based on the rotary magnetic dipole model, aiming at directly measuring the relative position and orientation between drill-bit and target-point. By investigating signal propagation rules of the rotary magnetic dipole, the paper demonstrated that the rotary magnetic dipole could be an equivalent of two perpendicular magnetic dipoles, and there existed a characteristic magnetic intensity signal, which could position the rotary magnetic dipole and be determined with the phase demodulation and amplitude demodulation of triaxial measureable magnetic signals by using the Hilbert Transform. The simulation results showed that the closer the rotary magnetic dipole to the target point, the smaller the positioning error, and the more accurate the orientation. The high-precision guidance method of wellbore trajectory based on the rotary magnetic dipole was of great value in drilling SAGD parallel wells in heavy oil development and horizontal intersection wells in coalbed methane development as well as in soluble salt mine development.

Key words: complex structure well, measurement-while-drilling(MWD), guidance, rotary magnetic dipole, magnetic-field signal demodulation

摘要：

传统随钻测量无法满足水平对接连通井、蒸汽辅助重力驱油中的成对平行井钻井等复杂结构井高精度导向定位技术需求。为直接测量钻头与目标靶点的距离及方位信息，提出了一种基于旋转磁偶极子模型的高精度导向定位方法。通过对动态旋转磁偶极子的磁信号空间传播规律的研究发现，旋转磁偶极子可以等效为正交磁偶极子的叠加，并且存在能够对旋转磁偶极子进行导向定位的特征磁场信号，该特征信号可以通过希尔伯特变换对三轴可测磁信号进行相位解调和幅度解调获得。仿真结果表明，钻头越接近目标靶点，定位误差越小，定位精度越高。基于旋转磁偶极子的钻井轨迹高精度导向定位方法对SAGD成对平行井、煤层气开发水平对接连通井及可溶性盐卤矿井高精度钻井轨迹导向定位具有重要应用价值。

关键词: 复杂结构井, 随钻测量, 导向定位, 旋转磁偶极子, 磁场信号解调