Petroleum System and Play Concept in the Area 113-3&4, Southern Margin of the Ghadames Basin, Libya

The Contract Area 113 Blocks 3 & 4 (Area 113-3 & 4) is located in the southern margin of the 
Ghadames Basin, where the glaciated Middle Ordovician Haouaz Formation and Silurian Basal Tanezzuft 
Hot Shale (BTHS) play important roles in the petroleum system. The newly acquired seismic data clearly 
indicate that the BTHS is distributed discriminatively in paleo-topographic lows surrounding Haouaz paleohigh structures. Maturation history is characterized by distinctive three heating phases and significant erosion 
of the post-Hercynian sediments, resulted in extremely high maturity of the BTHS in spite of its shallower 
present depths. In local depressions of the Area 113-3 & 4, the main hydrocarbon expulsion from the BTHS 
occurred in the Hercynian heating phase. The Haouaz Formation is divided into five (5) litho-stratigraphic 
units, Unit A to E in descending order. The Unit C sandstones have superior reservoir qualities, while those 
of sandstones in the other units are originally poor. Physical relationship/contacts between the Haouaz Unit C 
sandstones on the paleo-high structures and the surrounding BTHS are the most critical factor for formation of 
the Haouaz play from the viewpoint of hydrocarbon migration.