Stratigraphic Interpretation of Magnetotelluric Data in Central Saudi Arabia

Abstract

The pre-Khuff interval of the Paleozoic sediments in central Arabia is poorly defined by conventional seismic techniques, although this layer has significant potential for hydrocarbon exploration. Model studies indicated that magnetotelluric methods could outline the regional changes expected in the pre-Khuff in the area, which are largely dependent on the topography of the Precambrian basement. The Hercynian orogenic event created an extensive block-faulted terrane of half-grabens and horsts. The Hercynian structural relief was infilled in the Permo-Carboniferous and faulting reactivated in Triassic and later time, but the relationship between pre-Khuff and post- Khuff structure was impossible to understand using seismic data alone. In this survey of almost 500 magnetotelluric (MT) stations, essential control on the shallower section was provided by seismic interpretations, in addition to well log data for depths and resistivities. The MT method was very successful in confirming the presence of significant pre-Khuff section over some basement structures, as well as defining areas where the section is thin or absent which may be suitable for further exploration for stratigraphic traps.