The Hanifa Formation has a high-economic value in Saudi Arabia and many middle-eastern countries where it exists both as a reservoir and source rock. A few examples of the super-giant oil and gas fields that have Hanifa reservoir in the subsurface include Berri and Khurais fields. In this project, an analogue core for Hanifa reservoir facies that was drilled behind-the-outcrop, ~ 150 km south of Riyadh, along the Tuwaiq Mountain escarpment is studied. The main objective of this study is to analyze the vertical facies heterogeneity of Ullayah Member of Hanifa Formation. Thus, for this study sedimentological, petrographical, and petrophysical data have been collected and analyzed at a very high resolution. Based on the sedimentological, petrophysical and petrographic interpretation, four different vertical facies associations can be defined, representing distinct depositional environments (vertically): 1) High energy-level proximal shoreline, intraclastic grainstones deposition with moderate-Vp, relatively low-GR signature ; 2) Relatively low energy-level lagoonal depositional setting with low-Vp, high-GR represented by wackestones/packstones that has lagoonal microfossils and dasyclad algae; 3) Back barrier reefal depositional setting with moderate Vp, low-GR signature represented by stromatoporoids and corals, and 4) Oncoidal depositional setting with moderate-Vp, low- GR signature, mainly composed of ellipsoidal oncoids. Overall, the facies from these environments have been systematically vertically stacked on top of each other (in core WB-01), representing a deepening upwards trend and followed by shallowing oncoidal facies. This interpretation is also well match in regional context (GR data) and can be used as correlation reference.
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|KAUST Research Repository