3D frequency domain controlled source electromagnetic numerical modeling with coupled finite-infinite element method

Due to the large scale of the survey domain, the three dimensional (3D) controlled source electromagnetic (CSEM) numerical modeling usually brings about large amount of data and is very time consuming. To solve these problems, in this study, infinite elements were introduced into the finite element analysis to substitute the conventional artificial boundary conditions, which made the electromagnetic fields diffuse to infinity and attenuate to 0. As a result, the discretization domain for finite elements, as well as the total number of degrees of freedoms and time consumption, can be reduced remarkably. The numerical tests show that with the finite-infinite element coupling algorithm, the finite elements discretization domain is less than 1% of the conventional finite element modeling. The total numbers of freedom degrees are reduced around 33%, and time consumptions are saved around 25% while the accuracy is equal.