Current status and prospects of 3D EM forward and inverse modeling technology

Three-dimensional (3D) electromagnetic (EM) forward modeling and inversion have become a prominent research focus in EM data processing and interpretation, owing to their strong capabilities in handling complex geological structures, delineating fine-scale features, and providing realistic numerical simulations. Despite rapid development, this technology still faces significant challenges, primarily due to limitations in methodology and computational resources. These challenges are primarily manifested in inefficient computation, inadequate accuracy in 3D forward modeling for complex geological models, limited stability during the 3D inversion process, and pronounced non-uniqueness of the inversion solutions. While the fundamental algorithms and principles of 3D EM forward modeling and inversion techniques are relatively mature, recent research efforts and achievements predominantly aim to address these three pivotal issues. In this paper, we systematically review the progress made by researchers worldwide over the past two decades and highlight the latest developments in 3D EM forward modeling and inversion. This review is anticipated to clarify the current cutting-edge techniques, to illuminate future trends and foster further theoretical innovation and practical application of 3D EM techniques.