A COMMON SOURCE-ROCK FOR EGYPTIAN AND SAUDI HYDROCARBONS IN THE RED-SEA

The northern Red Sea area hosts a classic triple junction of the Red S ea, Gulf of Aqaba, and Gulf of Suez rifted basins. The sedimentary suc cession here can be divided into prerift (pre-Miocene) and synrift (Mi ocene and post-Miocene) megasequences. The prerift section has been pe netrated in only a few wells drilled on the western (Egyptian) side of the Red Sea, whereas the synrift section is known on both the Egyptia n and the Saudi sides of the Red Sea, Although the synrift units on bo th sides of the water are similar in facies, thicknesses, and depositi onal environments, they have different stratigraphic nomenclatures. Th e northern Red Sea consists of elongated troughs separated by elongate d structural highs, both of which trend northwest-southeast (Gulf of S uez trend). These highs are dissected by cross elements trending north east-southwest (Gulf of Aqaba trend) and east-northeast-west-southwest , and are looked upon as strike-slip faults dislocating these highs, I dentified rich source rocks are present in the upper Senonian carbonat es, the Sudr and Duwi formations on the western side of the sea, the e arly Miocene Rudeis Formation (Burqan Group), and the middle Miocene K areem and Belayim formations (Maqna Group). The pre-Miocene and the ea rly Miocene source rocks host oil-prone kerogen, whereas the middle an d late Miocene source rocks contain oil-and gas-prone kerogen, All of these source rocks are sufficiently mature in most of the deep hydroca rbon kitchens to generate hydrocarbons. Using both bulk and specific p arameters, the correlation of liquid hydrocarbons and source rock extr acts from the northern Red Sea suggests three scenarios. (1) The Egypt ian and Saudi Red Sea oils form one genetic family that is different f rom the typical Gulf of Suez oils, The Gulf of Suez oil is sourced fro m the upper Senonian carbonates, but the northern Red Sea oil (Egyptia n and Saudi) is sourced from the lower Miocene Rudeis Formation and th e middle Miocene Kareem and Belayim formations (Burqan and Maqna group s; respectively), (2) The northern Red Sea oil group is characterized by a relatively higher wax content, low sulfur content, a pristane/phy tane ratio of more than 1.0, a dominance of C-29 steranes, and an abun dance of the biomarker gammacerane; the interpretation of these parame ters suggests the possibility of two sources for these oils: a silicic lastic marine source and a relatively restricted, nonmarine source. (3 ) Both the Gulf of Suez oil group and the Red Sea oil group may mix in one field.