Exploration Insights February 2020

8 | Halliburton Landmark Exploration Insights | 9 North-east South-west Pseudo 1 Quseir A-1X Quseir Pseudo 2 B-1X Pseudo 3 Shagara 0.8 Ro Early Oil 1.35 Ro Main Oil/Late Oil 0.6 Ro Mobile Salt Kareem-Zeit Rudeis 2.0 Ro Gas an a- Rah rd Wa One possible exploration risk associated with this play is the potential impact of high heat flows on reservoir quality. The more deeply buried Nubian sandstones are more likely to have suffered porosity degradation through chemical compaction and cementation. Less deeply buried graben and those closer to the coastline where heat flows are lower (Figure 3) could, therefore, represent the best locations to target this play. In order to mitigate exploration risk, 3D thermal modeling combined with high-quality seismic with good resolution beneath the salt would be required. Due to very high beta factors, Nubian reservoir presence is expected to be limited to tectonically isolated blocks throughout the basin, preserved within basement lows. Although exhumation of Nubian facies along the crests of rotated fault blocks represents a concern for reservoir preservation, seismic mapping indicates that fault block size in the northern Red Sea is similar to the Gulf of Suez, where Nubian reservoirs are producing (Gordon et al., 2010). To help predict the distribution of Nubian reservoirs offshore, structural and basement relief mapping was used to identify these basement lows (Figure 4), using a combination of well data, free-air gravity, magnetic, and limited seismic data (e.g. Cochran and Karner, 2007). Pseudo 4 Shagara Mobile Salt Kareem-Zeit exploration wells have yet to encounter the pre- rift section offshore. Syn-rift Siliciclastic Reservoir In the Gulf of Suez, present-day drainage outputs coincide with thick packages of Early Miocene syn-rift strata (Polis et al., 2005). This suggests that during Miocene rifting, drainage networks Basal heat flow increases with proximity to rift axis 30°0'0"E N Data control for modeling Middle–Late Miocene Exhumed Mantle Present-day heat flow data Early Miocene Basement Geothermal gradient data Lithological control 1 Figure 3> Location of the six basin models along the studied transect in the Egyptian Red Sea (location of transect shown on Figure 1). Results are illustrated by the 0.6, 0.8, 1.35, and 2.0 Ro lines, which depict how the depth of the oil and gas windows changes along the transect due to variations in salt thickness, overburden, and heat flow. The chance of oil charge is high risk, but is most likely at the basin margins where beta factor and heat flow are lowest. First generation from modeled source rocks began at ~20 Ma and continues at present day, though again heterogeneous salt, heat flow, and overburden thickness mean timing of generation varies across the basin. The presence of over-mature source rocks increases the likelihood of gas flushing of oil sourced from younger source rocks, but it is possible that local pockets of oil could remain. RESERVOIR PREDICTION Analogues from producing fields in the Gulf of Suez suggest the most prospective reservoir targets in the Egyptian Red Sea will be: Cambrian–Cretaceous pre-rift sandstones (Nubian Group), Early Miocene syn- rift sandstones (Rudeis and Kareem formations) and Early–Middle Miocene syn-rift carbonates. To predict the likely distribution of these reservoir facies, structural mapping, gross depositional environment mapping, and source-to-sink methodologies were applied. Legend 2 3 International Boundaries License Blocks 2019 4 Catchment Area (km 2 ) 25–1,000 25°0'0"N 5 1,001–10,000 10,001–100,000 25°0'0"N 6 100,001–1,000,000 1,000,001–10,000,000 7 Modern Drainage Rivers (by Strahler Stream Order) 8 Structural Elements 9 Normal Fault Strike-Slip Fault Continent-Ocean Boundary 30°0'0"E 10 10 Thrust Fault Nubian Pre-rift Siliciclastic Reservoir A critical, unresolved issue is the preservation of pre-rift Nubian reservoirs within the Egyptian Red Sea. Nubian sandstones are prevalent in the Gulf of Suez with extensive outcrops onshore along the Egyptian Red Sea coast, and the Cretaceous section has been penetrated on the conjugate Saudi margin (Birkle et al., 2018). However, Saudi Arabia Egypt © 2020 Halliburton Maturity windows for all potential source rock horizons vary significantly across the transect. There is localized potential for both oil and gas generation at present day, though in the most deeply rifted sub-basins, all source rocks are likely to be over mature. Depth (km) 0 Depth control Paleozoic–Early Cretaceous Late Cretaceous–Eocene Early Pliocene Late Pliocene–Pleistocene 100 km Oligocene 40°0'0"E Legend 35°0'0"E Sudan 35°0'0"E Red Sea © 2020 Halliburton 40°0'0"E Figure 4> Offshore basement relief map of the Northern Red Sea Basin overlaid with interpreted structural elements. Areas where post- and syn-rift siliciclastic reservoirs are most likely to be preserved are highlighted in yellow, predicted to correspond with basement lows. Modern-day drainage networks and catchment areas for the surrounding hinterland are depicted, styled by catchment area. The thickest syn-rift siliciclastic reservoirs are expected to lie in areas adjacent to the largest modern-day catchment, which are predicted to have been comparable during the Miocene–Pliocene (illustrated in the darker green). Syn-rift carbonate reservoirs are anticipated to have developed over the largest outboard paleo highs, highlighted in white.

Exploration Insights February 2020 | Page 8