oa Integrated Basin and HC Systems Model, Silurian-Carboniferous, Southern Algeria

Paleozoic basins of southern Algeria comprise several HC systems: i) infra-Cambrian (?) source rock,<br>Upper Ordovician reservoirs; ii) Silurian source rock, Lower and Middle Devonian reservoirs ; iii) Upper<br>Devonian source rocks, Lower Carboniferous reservoirs. Since 2006 commercially productive gas<br>reservoirs have been proven by several wells in the Reggane and Ahnet Basins. Previous basin<br>evaluation has proposed HC generation predominantly during Mesozoic reburial, with pre-Hercynian<br>generation having been largely ineffective (Purdy & MacGregor 2003, Geol. Soc. Spec. Publ. London, v.<br>207). Thermochronlogical data (Logan & Duddy 1998, Geol. Soc. Spec. Publ. London, v. 132) have<br>indicated two-phased HC generation: i) simple burial heating to oil window before peak Hercynian<br>orogeny (pre-Early Carboniferous); ii) Late Triassic heating to wet and dry gas window in the Latest<br>Triassic, related to the development of the Central Atlantic Magmatic Province (CAMP) and doleritic<br>dykes/sills (Reggane Basin); iii) subordinate heating of less mature basin margins until recently.<br>In order to better assess the basin and HC development including the recently proven gas plays, an<br>integrated study has been performed including: i) seismic and sequence stratigraphy at basin and<br>reservoir resolution; ii) numerical basin modeling (subsidence/uplift, sediment flux); iii)<br>palynostratigraphic (miospores, acritarchs) and organofacies analysis; iv) paleotemperature analysis<br>including organic maturation, apatite and zircon fission track and (U-Th)/He dating. Focus is on the<br>Reggane Basin, where ample 2D seismic coverage and calibration wells (logs, samples) have been<br>available. Results include: i) trans- and regressive trends within the basin fill; ii) intra- and inter-basin<br>correlation iii) lateral continuation and vertical connectivity of reservoir sandstones; iii) accommodation<br>and sediment flux history; iv) paleotemperature development related to pre- and post-Hercynian burial<br>and exhumation. The new data show, that the existing models of HC development for the Upper<br>Silurian-Lower/Middle Devonian and Upper Devonian-Lower Carboniferous systems have to revised.