固定翼电磁数据双分量联合电导率深度成像

Conductivity-Depth Imaging of Fixed-Wing Airborne Electromagnetic Data

传统固定翼航空电磁探测采用总场dB/dt进行电导率深度成像,不仅损失多分量测量信息,dB/dt与电导率的非唯一性也影响数据的成像精度。笔者提出了一种基于磁场双分量(Bx,Bz)查表的联合电导率深度成像算法,根据固定翼电磁响应的正演计算,建立按时间道划分的Bx-Bz-电导率-飞行高度数据表,利用磁场双分量联合查表与插值算法确定视电导率,避免了由于电磁数据二值性引起的视导率不确定性问题;根据扩散深度公式得到视深度,并计算成像深度,从而得到双分量联合电导率深度成像结果。基于一维大地模型正演数据与准二维大地模型正演加噪数据,分别采用磁场双分量联合查表法、总场查表法和单分量查表法对仿真数据进行电导率深度成像,结果表明磁场双分量联合查表法优于单分量与总场查表法,较单分量电导率深成像精度提高了7%。

The traditional fixed‐wing airborne electromagnetic survey lost multi‐component measurement information for the reason of using the total field as the data base for the conductivity depth imaging . The imaging precision is decreased due to the non‐uniqueness of the dB/dt .A joint conductivity depth imaging approach based on the lookup method of two‐component B field response is proposed .Based on the fixed‐wing electromagnetic forward calculation ,this paper establishes a table of Bx B z‐conductivity‐altitude ,uses B field to avoid the uncertainty of conductivity due to the binary value of electromagnetic data , uses the joint lookup method of two‐component B field and interpolation algorithm to determine the conductivity ,and then takes the advantage of the diffusion depth formula to obtain the depth ,and finally to process the joint conductivity depth imaging .Compared to the total field and simple component lookup method applied in the one‐dimensional and quasi‐two‐dimensional forward simulation ,the CDI of two‐component B field gets more ideal fitting effects ;and the imaging precision is improved by 7% .