Abstract Libya produces 1.74 million barrels of oil a day. Future exploration and development will increase this amount. The producing sedimentary basins in Libya are the Sirt, Ghadamis, Murzuq, and Tripolitania Basins, collectively containing the country’s major 320 producing oil fields. The total reserves exceed 44 billion barrels of recoverable oil and 37 trillion cubic feet of gas. The Silurian and Upper Cretaceous sections, righ in type II kerogen, form the source rocks for the petroleum and gas in these basins. The petroleum systems of the five major onshore sedimentary basins—Sirt, Murzuq, Kufrah, Ghadamis, and Cyrenaica—and the offshore Tripolitania Basin are described in this paper.

Abstract As the traditional exploration plays in the main productive basins of North Africa and the Middle East become more ‘mature’, attention is increasingly focusing on more challenging, older and deeper plays in the main producing basins and on high-risk, but more conventional, plays in under-explored frontier areas. This shift brings with it a range of technical and commercial challenges that must be addressed, if exploration in the region is to remain an attractive proposition. Exploration in North Africa and the Middle East has traditionally focused on the prolific Mesozoic- and Cenozoic-sourced petroleum systems of the Nile Delta, the Sirte Basin, the Pelagian Shelf, and the Arabian Plate and on the Palaeozoic-sourced petroleum systems of the Berkine, Ghadames, Illizi, Ahnet and Murzuq basins, the Central Arabian Basin, the Qatar Arch and the Rub Al Khali Basin. Together these form one of the most prolific petroleum provinces in the world and, as a consequence, there has been little commercial incentive to invest in exploring more challenging and riskier plays in these areas. However, as the need to find new reserves becomes imperative, attempts are increasingly being made to test new play concepts and to extend already proven plays into new areas. Key recent developments in this regard include the recognition of the hydrocarbon potential of the Neoproterozoic to Early Cambrian (‘Infracambrian’) sedimentary section lying below the traditionally explored Palaeozoic succession in many basins in North Africa. In some areas, particularly the Berkine Basin in Algeria, the Nile Delta in Egypt and the Rub Al Khali Basin in Saudi Arabia, attention is also increasingly being focused on developing deeper gas plays, both in new areas and beneath existing producing fields. The technical challenges associated with these deeper gas plays are immense and include difficult seismic imaging of deep prospects, low porosity and permeability, high temperature and pressure and a critical need to identify ‘sweet spots’ where either locally preserved primary reservoir characteristics or secondary enhancement of reservoir quality through palaeo-weathering and/or fracturing allow commercial rates of gas production to be achieved. Despite these challenges, it is clear that the future for exploration in many of the more mature basins of North Africa and the Middle East will increasingly lie in evaluating such older and more deeply-buried plays.

Abstract The lower Carboniferous (Tournaisian to Visean) of North Africa is characterized by cycle-stacks of predominantly shelfal to marginal marine sandstones and limestones, thick shelfal mudstones and less common but important interbedded fluvio-deltaic sandstones. The cyclic sedimentation pattern continues into the Mid Carboniferous (Serpukhovian to Bashkirian), when mixed siliciclastic–carbonate sequences give way to tropical carbonates, before an abrupt return to continental deposits in the upper Carboniferous (Bashkirian to Gzhelian). The alternation of widespread shallow marine and more discrete fluvial reservoirs with interbedded offshore mudstone seals is interpreted to result from high-frequency, high-amplitude Carboniferous glacio-eustatic sea-level changes. The large base-level changes during that time, combined with climatic conditions that produced high amounts of terrigenous mud, provided favourable conditions for the development of stratigraphic traps in the clastic-prone lower Carboniferous, while the advent of tropical carbonates produced reefal buildups in the Mid Carboniferous. Four stratigraphic trapping types are recognized: (1) truncation traps in which reservoir units were eroded on subaerially exposed proximal palaeohighs and thick underlying transgressive and highstand systems tract (TST and HST) mudstones form the bottom-seal and the rapid transgression of the offshore facies forms the top-seal; (2) pinchout traps of lowstand wedges on the flanks of distal palaeohighs, which were only affected by subaqueous reworking of previous TST–HST mudstones and were buried during the subsequent transgression; (3) incised valleys of the lowstand systems tract (LST), filled with thick fluvial and tidal sandstones, cutting either into TST–HST mudstones in the lower Carboniferous, or into exposed carbonate platforms in the Mid Carboniferous; (4) Waulsortian-type reefal buildups of the Mid Carboniferous. The four trapping types are discussed using selected outcrop examples, and are placed into regional sequence stratigraphic context of the Carboniferous depositional systems and sequence development of North Africa. These concepts can be readily applied to the subsurface and offer significant potential for new plays across North Africa.

Abstract The A1-NC198 exploration well was drilled in the Kufra Basin in 2007 by RWE Dea and represented only the third well in a large, 400 000 km 2 frontier basin. Despite being dry and lacking any hydrocarbon shows, the well provides important data to improve the understanding of the regional petroleum play. In the 1980s and 1990s the basin's prospectivity was questioned largely because of supposed (1) lack of structuration, (2) lack of source rock and (3) thermal immaturity at Silurian level. Following a series of academic and industry studies over the past 10 years, these assertions can no longer be upheld. The analysis of available seismic has proven the existence of Murzuq-style fault blocks as well as late Ordovician glacial erosional relict buried hills, potentially forming suitable structural and stratigraphic traps. The presence of hot shale in the Kufra Basin is evidenced by typical seismic onlaps of strong amplitude reflectors at base Silurian levels, shallow drilling results and outcrop spectral gamma-ray evidence. A spore colouration study of A1-NC198 cuttings indicates a deep oil window maturity for the Silurian, implying potential oil generation in the basin if suitable Silurian source rocks exist. The stratigraphy of the A1-NC198 succession was analysed by means of biostratigraphy and chemostratigraphy, which form the basis for improved well correlations within the basin.