Basement structure investigation using 3-D forward modeling and inversion of geomagnetic data of the Zeit basin area, Gulf of Suez, Egypt

Abstract

The Zeit basin is located on the western coast of the Gulf of Suez. It is a major, elongated half-graben structure with faults dipping steeply to the southwest. The Zeit basin contains the thickest Miocene sediments and evaporites in the Gulf of Suez. Many exploration activities have been conducted in and around the study area due to the known presence of hydrocarbon resources. In petroleum exploration, the estimation of basement depth (or sedimentary thickness) is a primary exploration risk parameter, in particular, for estimation of heat flow. The magnetic method is one of the few methods that can be used to study the basement structure and estimate the top basement depth. In this paper, the top basement geometry, distribution of the magnetic susceptibility and the basement depth of the Zeit basin were investigated using 3-D forward magnetic modeling and the 3-D inversion of geo-magnetic data. The 3-D forward modeling of the aeromagnetic field data from the Zeit basin area revealed a NW-SE trending half-graben structure, consistent with the known geology of the study area. Magnetic susceptibility cutoff 0.005 SI was applied to show the subsurface relationships among the basement sedimentary units. The calculated depth of the Zeit basin is around 4–5 km. The magnetic field data, calculated using the Gauss Legendre quadrature method, generally agree with the measured data as well as data calculated using the inversion process. The depth and magnetization intensity values used in the 3-D forward modeling, as well as petroleum borehole data, provide a structural basis for the 3-D inversion process.