Lower Cretaceous Buwaib Formation Northeast Saudi Arabia: Facies Changes – Implications for Hydrocarbon Prospectivity
N.M. Dossary1, H. Tourqui1, K. Ertug1, and S. Khan1
Stratigraphic and sedimentological analyses were carried out to understand facies changes in the Lower Cretaceous Buwaib Formation in Northeast Saudi Arabia by using core, cuttings and log interpretations. The lower limit of Buwaib Formation overlies the Yamama Formation conformably but with a distinct faunal and lithologic change. The upper limit with the Biyadh Formation is represented by a regional unconformity marked by a distinct facies change. The integrated biostratigraphic data and sedimentological interpretation indicates that the Hauterivian upper section of the Buwaib Formation was deposited in a mixed siliciclastic tidal setting and carbonate shallow marine environments. Fourteen lithofacies, grouped into five facies associations, were identified from cores. Three transgressive-regressive cycles were identified. The sediment supply is restricted to the southwestern area, with carbonate and shale located toward the east. The development of stratigraphic traps is possible toward the northeast. The upper Buwaib Formation clastic deposit contains excellent quality reservoirs. The best reservoir quality, corresponding to distributary channels, occurs in the proximal settings and deteriorates towards the east and the northeast. Petrographic analysis indicates the Buwaib Formation clastic reservoir quality is controlled mainly by its depositional environment. The sandstones are dominated by subangular grains of monocrystalline quartz with minor amounts of feldspar, heavy minerals, glauconite pellets and deformed mudclasts. Porosity is best preserved in clean sandstone and is dominated by well-connected intergranular pores.
AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain