瞬变电磁测井同轴多匝线圈误差校正模型

Error correction model of coaxial multi-turn coils for transient electromagnetic logging

受井眼尺寸限制,井下瞬变电磁系统通常采用同轴多匝接收线圈来改善探测性能。但是,线圈匝数的增加在提高信号强度的同时,也引入了模型失配误差。针对该问题,本文在柱状多层非均匀结构基础上,分析了接收与发射线圈间距对感应电动势的影响,并提出了一种瞬变电磁测井同轴多匝线圈误差校正模型。最后,不同收发间距的仿真结果表明,该模型可以有效校正多匝线圈模型失配误差,提高瞬变电磁测井反演精度。

Due to the limitation of borehole space, coaxial multi-turn receiving coils are usually utilized to improve the detection performance of downhole transient electromagnetic system. However, model mismatch error will also be introduced as well as the enhancement of the strength of induction signal with the increasing of the number of the turns. In order to solve this problem, on the basis of the inhomogeneous cylindrical multilayer structure, an error correction model for coaxial multi-turn coils in transient electromagnetic logging is presented, where the influence of space between receiving and transmitting coils on the transient response is also analyzed. Finally, simulations for different transmit-receive distances are conducted and the results demonstrate the effectiveness of the proposed model for mismatch error correction of transient electromagnetic logging.