Offshore Sub-Basalt Exploration Using CSEM and MT

Abstract

Seismic sub-basalt imaging is challenging and often leaves remaining uncertainties about the sub-basalt structures. This paper considers how the marine controlled source electromagnetic (CSEM) and the magnetotelluric (MT) method can reduce the interpretation uncertainty by providing structural and quantitative resistivity information about the thickness and extent of the basalt sequence and the sediments below. In order to demonstrate the capability of these technologies, we will present two recent studies: (1) a synthetic inversion test from a realistic model based on well-log and seismic data and (2) inversion of field data acquired over the Faroe-Shetland Escarpment. We will show that this information can also be used to improve the velocity models for seismic depth imaging.