Defining New Exploration Play Potential in the Offshore Sirt Basin, Libya, Using Mega-Regional 2-D Seismic Data

Abstract

The onshore Sirt Basin, Libya, has yielded some of the world’s largest petroleum discoveries, with estimated oil reserves of 123 billion barrels. The offshore extent of this system, however, is poorly constrained due to limited exploration activity and a poor understanding of the complex geological history. Recent wells have proven both equivalent and new petroleum systems in the offshore, but the extent, character and full potential of these systems is currently poorly understood. Furthermore, the structural complexities of the offshore area and the relationships between the ancient crustal domains is only starting to be realized. Placing the offshore Sirt Basin and adjacent Cyrenaica Margin into a regional context and understanding the relationship with the onshore basins will be key to future exploration of this potentially huge yet underexplored province. Over 45,000 km of recently acquired and depth processed deep regional seismic data and newly reimaged legacy 2D seismic data has been interpreted and integrated with offshore well data in a mega-regional basin study. These data allow a well constrained crustal-scale structural and tectonic model to be defined and placed within the regional context of the tectonically complex central Mediterranean. For the first time, deep imaging of the pre- and early rift basin is interpreted within a structural context to pull together the full tectonostratigraphic history of the offshore Sirt Basin and Cyrenaica Margin, from Hercynian Orogeny to Mesozoic extension and Cenozoic inversion. Regional stratigraphy from the Palaeozoic to present, has been interpreted in the context of assessing the petroleum potential of this structurally complex region. Basin modelling of several proven and speculative source rock units shows the significant offshore potential for both oil and gas maturation, and optimal timing of trap formation. Enhanced understanding of the regional context of proven and speculative plays is presented, extending the petroleum potential of the offshore along the Cyrenaica Margin and into the deeper water. The regional stratigraphic interpretation is placed into a structural context in order to understand the deposition and development of reservoir facies, source rock maturation and migration and trap development to fully integrate the petroleum potential of the offshore Sirt Basin and Cyrenaica Margin.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018