基于非结构化网格的频率域井地电磁2.5维正演研究

Research on 2.5D forward of borehole-surface electromagnetic method in frequency domain based on unstructured grid

井地电磁方法是将发射源放置在井中,地面测量电磁场,具有精度高、效率高等特点。目前针对这种方法的研究较少,且传统研究方法均基于结构化网格,不符合实际情况,同时现有研究也大多限于直流电井地电法,而实际应用中直流电勘探受限于发电机功率,其勘探深度有限。针对此情况,这里开发了基于非结构化网格的频率域2.5D井地电磁法的正演程序,通过多种模型试算,验证了井地电磁法的有效性和实用性,为进一步研究工作打下了基础。

Put the source into the well and place the receiver on the ground can improve the SINR and react the underground structure more sensitive.Borehole-surface EM is one of this kind of method.It puts the source into the well and measure EM on the ground with high accurate and high efficiency.At present there is few research on this kind of method,and the traditional research method is based on structured gird which doesn＇t meet the fact.Meanwhile most of research focus on the DC which makes the method has less exploration depth.This paper adopts unstructured gird to develop the 2.5DBorehole-surface EM forward program.Besides,we show the practicability of 2.5DBorehole-surface EM through computing complex mode and provide theoretical foundation for the next inversion research.