By Maggie Williams

The PESGB Liverpool Branch meeting held on 19th April was once again hosted by the Department of Earth, Ocean and Ecological Sciences at the University of Liverpool. At this meeting branch members welcomed Prof Jonathan Redfern from the North Africa Research Group at the University of Manchester. Jonathan gave a fascinating and well-illustrated lecture: “Chasing the Triassic Continental Sandstone Play Fairway across NW Africa: Characteristics, Challenges and Opportunities”.

In his talk, Jonathan covered the Triassic regional plate tectonic setting, climatic conditions and depositional setting of North Africa. Jonathan explained how during the breakup of Pangea, Triassic rift basins developed across North Africa and that these rift basins were initially filled by thick sequences of continental red beds comprising ephemeral and perennial fluvial sandstones, aeolian sandstones, alluvial fan conglomerates, playa, floodplain and lacustrine mudrocks.

Toward the end of the Triassic many of these rift basins experience a transgression with deposition of marine limestones and mudstones and Jonathan explained how, where palaeogeography and climatic conditions were conducive, thick sequences of evaporites were deposited and now act as a regional super-seal. This interval forms an important reservoir across North Africa, with over a billion barrels discovered in Algeria, Libya and Tunisia. Jonathan described how the Triassic system is now being actively explored in Morocco, with the recent Tendrara wells drilled by Sound Energy testing gas from Triassic sandstones, extending this play fairway to the west. There are many other Triassic rifts along NW African margin where a similar play exists, some undrilled, whose prospectivity is unknown.

The talk reviewed our understanding of the controls and characteristics of the main depositional systems, reservoir distribution and quality, source and seal and implications for the petroleum system. Jonathan finally discussed challenges for exploration and development and the opportunities for this play along the NW Africa margin.