oa Source Rock Characterisation of Sediments from the Tarfaya Basin and Adjacent Areas, Morocco

Thermal maturity information has been compiled for the Tarfaya Basin, Morocco and surrounding<br>areas. Tarfaya Basin is bounded by the Anti-Atlas, the Reguibat High / Tindouf Basin and the<br>Mauretanides and developed since the opening of the Atlantic in the Permian to Triassic with<br>continental extension. Little is known about source rock potential in Tarfaya Basin, excluding<br>Cenomanian/Turonian black shales which were investigated e.g. by Kolonic et al. and Kuhnt et al. in<br>great detail. In general Lower Silurian, Upper Devonian, Lower Jurassic, Lower Cretaceous, Albian,<br>Cenomanian as well as Lower Tertiary shales are considered as source rocks. To get more information<br>about their potential, cuttings and cores from on- and offshore wells as well as outcrop samples<br>covering a large area (locations in Tarfaya Basin, Tindouf Basin and Bas Draa area) were collected.<br>TOC/TC and sulphur measurements, Rock-Eval pyrolysis, vitrinite reflectance measurements and<br>organic-geochemical analyses were carried out on these samples to get basic information on their<br>thermal maturity and the potential to generate hydrocarbons. Based on these data the burial and<br>thermal histories of several wells/pseudo-wells were modelled using PetroMod 1D. The modelling<br>results lead to the conclusion that in some areas highest temperature was reached at recent times in<br>accordance with deepest burial. The reconstructed temperature history shows moderate heat flow,<br>excluding times of rifting at present. The present day heat flow was modelled with values between 50<br>and 60mW/m2. In other areas, strong erosion took place and diagenetic paleotemperatures exceeded<br>present-day temperatures by far.<br>High TOC values were established for Eocene sediments in the southern part of the Tarfaya Basin (up<br>to 7%). In the Santonian, Coniancian and Campanian TOC values range between 1 and 6% and are<br>even higher in the Cenomanian/Turonian black shales. Most of the samples are representing a type-II<br>kerogen, whereas some of the Eocene samples contain type-I kerogen. Maturity of the samples is low,<br>i.e. they are immature or at the beginning of the oil window. Tmax values range between 400 and<br>450°C and Production Index is lower than 0.1. Furthermore molecular geochemical data provide a<br>more specific overview about the depositional environment and the maturity distribution.