Controlled Source Electromagnetic System Adapted to the ROV Victor 6000: A Contribution to Deepsea'nnovation Project

Electromagnetic properties of Earth materials are important geophysical parameters and serve as good proxies for fluid-related processes, as their variations are directly linked to changes in porosity, connectivity, fluid flow, or magnetization of the porous network, as well as to the composition of fluids and the properties of mineral surfaces. In the oceanic crust, electromagnetic imaging provides key insights into the geometry of hydrothermal conduits and the distribution of fracturing and alteration. In sedimentary environments, it can also reveal the geometry of sedimentary bodies, map fluid migration conduits, and detect the presence and distribution of natural gas and gas hydrates within the upper tens to hundreds of meters of the seafloor. Within the Deepsea'Nnovation program (DSN) [1] this project proposes an innovative approach: adapting an ROV-based electromagnetic imaging methodology developed in our laboratory, originally inspired by large-scale controlled-source electrical transmitter/receiver systems. This method has already demonstrated its effectiveness in shallow water environments (less than 100 m depth). For high-resolution electromagnetic imaging in the deep sea, using an ROV is essential, as it allows deployment of an electrical source with sufficient power. The project aims to develop an ROV-mounted electromagnetic source paired with electric potential receivers. The system will be designed to accommodate different receiver configurations—varying in number, type (fixed or mobile), and deployment strategy. It will enable profile acquisition at exploration scale, with a penetration depth of up to a few meters below the seafloor.