Chapter 8 - Petroleum source and reservoir rock re-evaluation in the Kufra Basin (SE Libya, NE Chad, NW Sudan)

Abstract

This chapter discusses that the source-rock potential of the Kufra Basin is currently unclear. The Tanezzuft shales have been described as being up to 130 m thick in outcrops at the basin margins, but the shales are thin and mostly replaced by siltstones and sandstones in two dry exploration wells drilled in the northern part of the basin. Hot shales are interpreted to have been deposited in palaeodepressions, such as incised valleys of the preceding lowstand or in intrashelf basins during the initial transgression after the melting of the late Ordovician ice cap. Fieldwork in the Kufra Basin has shown that the basal Tanezzuft horizon is mostly not exposed on the northern and eastern margins of the basin. A detailed evaluation of the lower Silurian source-rock potential may require shallow stratigraphic drilling. Deep infracambrian rift grabens have been interpreted on seismic lines from the Kufra Basin and, in analogy to Oman and Algeria, could contain organic rich intervals; this succession in the Kufra Basin may contain a second major potential source rock and warrants further investigation.