Palynofacies analysis and source rock evaluation of the Upper Cretaceous-Oligocene succession in the Drazia-1 well, Alamein Basin, Egypt

Abstract

Visual palynofacies analysis and petroleum source rock assessment are reliable and widely used applications for hydrocarbon potential. The Alamein Basin located in the north Western Desert is one of the promising hydrocarbon provinces all over Egypt. In this context, a total of 59 cutting samples representing the Upper Cretaceous Khoman formation and the Paleocene-Oligocene Apollonia and Dabaa rock units from the Drazia-1 well drilled in the East Yidma Oil Field, Alamein Basin, were analyzed. These samples were investigated for their palynological and palynofacies microscopy, including 39 samples for geochemical screening of their organic carbon content and 10 samples for Rock-Eval® 6 Turbo. Palynofacies analysis defined two palynofacies types of organic matter (OM). The first was characterized by phytoclasts-AOM composition of kerogen type III (gas-prone) and represents the Dabaa and Apollonia formations, and was deposited in a highly proximal shelf setting in marginal oxic-dysoxic conditions. The second was dominated by amorphous organic matter (AOM) and recognized in the Khoman formation, demonstrating a distal suboxic-anoxic basin with oil-prone kerogen type II. Moreover, geochemical analyses of the total organic carbon (TOC) content and the Rock-Eval pyrolysis determine the characteristics of possible source rock intervals and defined their hydrocarbon potentials. The investigated interval (4200–5150 ft) is suggested to be a poor source rock due to poor hydrocarbon potential of S2 values. The organic matter was thermally immature of kerogen type III (woody material typically generates gas). The palynofacies distributions and thermal hydrocarbon maturation in the Alamien Basin were affected by the tectonic movements that happened in the northern Egypt, mainly the Syrian Arc System.