Petroleum Systems Modeling of the Salt Province and Outer Margin Offshore Essaouira (Atlantic Margin of Morocco)

Abstract

Small fields and discoveries exist onshore Morocco and in the shallow water, but the offshore Atlantic margin remains a frontier exploration area. Salt tectonic activity resulted in a variety of potential traps, but also brings along many challenges. Recent deepwater wells failed to find viable reservoirs so far, however, numerous hydrocarbon shows have been encountered. The key to open the first deep water play is yet to be found, but international oil companies are currently engaged in the exploration of the Atlantic margin offshore Morocco.

In the presented work, regional thermal modeling, based on recently acquired 2D seismic reflection data (MIRROR experiment, 2011), took into account the geodynamic evolution from Early Mesozoic rifting and continental break-up to present day. Special emphasis has been put on integrating major Cenozoic events related to the Canary Islands hot spot and the collision between the African and Eurasian plates. A series of deep water anticlines is interpreted to have formed in the outer Atlantic margin offshore Essaouira as a response to the African plate passing over the hotspot during the beginning regional north-south compression. The thermal model allowed predicting the maturity of different potential source rocks and the timing relationship with the folding of the trap-forming deep water anticlines.

Both the duration of a Late Cretaceous hiatus, associated to the Base Tertiary Unconformity (BTU), and the Cenozoic sediment thickness present large north-south variations in the study area offshore Essaouira. As salt canopies are frequently embedded in levels at and above the unconformity, it can be postulated that both the hiatus and the sediment cover overlying the BTU influenced the present day allochthonous salt distribution within the Atlantic margin offshore Morocco. Structural restoration of one section within the salt basin has been performed, describing the diapiric salt rise and extrusion, and integrating the process of salt withdrawal and associated sediment deformation. Based on the obtained model, petroleum systems modeling was carried out to predict potential scenarios of source rock maturation, hydrocarbon expulsion, migration, and accumulations in the context of the salt deformation through geologic time. The elements (source, reservoir, and seal rocks) and dynamic processes (trap formation, charge, and preservation) of different potential petroleum systems are discussed, and promising salt-related and other play types will be presented.

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015