Self-excited Rotating Magnetization Field Ranging for SAGD Dual Horizontal Well

When the double row horizontal wells are applied to steam-assisted gravity drainage drilling, it requires guiding device in the drilled wells to assist drilling, thus it costs a large work and affects the normal production of the drilled wells. Focusing on the problem, this paper proposes a self-excited rotating magnetization field fluctuation ranging method while drilling. A set of magnets are designed to install at the rear of the drilling bit and rotating with the bit to generate a strong rotating magnetic field, which excite the drilled pipe sleeve or the screen tube to generate the magnetizing field. The magnetic fluctuation measured at the gauging point near the magnets with compensation magnetic, and its peak-to-peak is used to calculate the drilled wells relative distance. The simulation shows a negative correlation between the relative distance of drilled wells and the peak-to-peak of the magnetic fluctuation. Properly raise the excitation intensity can increase the peak-to-peak of magnetic fluctuation obviously. The magnetic fluctuation trend can effectively indicate the relative distance changes of the dual wells. The results demonstrate the feasibility of the magnetic fluctuation ranging method, which is significant to the development of the drilling instrument.