Effect of steel-cased wells on EM wave propagation for hydrocarbon detection

In controlled source electromagnetic (CSEM) modeling with well casings, it is common to assume that the current is flowing vertically in each casing, due to the large conductivity contrast between casings and their host media. This assumption makes the integration of the tensor Green's function relating the induced fields to source currents simple, since only the z-z component of the tensor needs to be considered. However, in practice, it can be improper to neglect the horizontal current effects in the casing without a close examination.

在受控源电磁（CSEM）建模中，针对井套管的情况，通常假定电流在每个套管中垂直流动，这是由于套管与其宿主介质之间导电性差异较大所致。此假设简化了与源电流相关的感应场张量格林函数的积分过程，因为只需考虑张量的z-z分量。然而，在实际操作中，若未经细致审查即忽略套管中的水平电流效应，则可能是不恰当的。