A signal acquisition and processing system for cluster wells ranging

As cutting-edge technology, cluster wells can substantially enhance wells production and oil recovery. Rotating Magnet Ranging System (RMRS) is critical technology to ensure precise ranging and accurate interconnecting target of complex structure wells. The magnetic signal of RMRS is a sinusoidal signal of frequency-varying, narrow band, and its intensity attenuates rapidly with cube of the propagation distance. When the distance is far away, the weak magnetic field signal is completely submerged by the environmental electromagnetic interference and the inherent noise of the detection circuit, which can not be detected accurately. According to the narrow band and varying frequency characteristics of rotating magnetic signal, a signal acquisition and processing system is designed for RMRS in order to track the varying frequency accurately and extract the weak amplitude precisely. System hardware included preamplifier, narrow band filter circuit, high precision A/D conversion circuit, control circuit and peripheral circuit. System software included digital filter algorithm and PC interface designing. A novel IQuinn-Rife method is proposed to effectively estimate the frequency of signal for RMRS under a strong interference background. Simulation results indicate IQuinn-Rife algorithm can improve the frequency resolution, avoid collecting useless frequency points, advance efficiency of the calculation speed and enhance accuracy of the results. The experiment verifies that the instrument is stable and reliable to quickly process the magnetic field signals while drilling in strong noise environment. The results indicate that the maximum effective ranging distance can be up to 50m for the adjacent well distance detection signals acquisition system, which can fulfill the requirements of drilling engineering in complex structure wells.