THE HYDROCARBON PROSPECTS OF THE RED SEA‐GULF OF ADEN: A REVIEW

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Abstract
The area reviewed covers some 825,000sq. kms. Since the early 1960s. 52 exploration wells have been drilled in the Red Sea. leading to four undeveloped (mainly gas‐condensate and dry gas) discoveries; twelve exploration wells have been drilled in the Gulf of Aden since the late 1970s, leading to one undeveloped oil discovery. Numerous surface oil seeps in the Red Sea testify to oil generation, while many of the drilled wells have also had shows.The syn‐and post‐rift Neogene stratigraphy of the Red Sea is very similar to that of the prolific oil‐producing Gulf of Suez graben, with source, reservoir and seal rocks widely present; pre Neogene rocks. however, are only present in patches. and include some marine Paleogene and Late Cretaceous sediments on older continental clastics in the northern half, and marine Jurassic on Basement in the southernmost sector. In the Gulf of Aden, the Neogene is less thickly developed, and lacks the widely‐occurring evaporite sequence of the Red Sea; the marine Paleogene and Creataceous‐Jurassic sequences of the pre‐rift succession are, however, welldeveloped, although the Jurassic is locally removed by block erosion.The tectonic evolution of the two rift basins is here discussed, and evidence for the areal extent of oceanic floor or stretched coninental crust. for episodic or continuous extension and sea‐floor spreading, and for pre‐rift doming and fracturing, is reviewed. It is concluded that episodic extension and spreading have occurred, and may be more advanced in the Gulf of Aden than elsewhere; this has been accompanied by higher paleo‐temperatures and geothermal gradients along the margins in the past, and high present‐day heat‐flow in the axial regions of both rifts. Overmaturation of the pre‐rift sequence in the southern margins of the Red Sea has resulted, aided by deeper burial, but contrary to prevalent views that the regions is too hot and gas‐prone, black‐oil potential in both basins is present at depths ranging from 1,000 m to a maximum of 4,500 m.Hydrocarbon play in the Red Sea is principally Neogene, and traps are provided by rotated Basement fault‐blocks and horsts in the pre‐evaporite sequence, and by salt flowage and piercement, together with stratigraphic pinch‐out, in the post‐evaporite sequence. In the Gulf of Aden, the main play is in the pre‐rift Paleogene sequence, while lower potential also exists in Neogene and Mesozoic successions. The Arabian side of the Red Sea has the widest and most poorly‐explored shelf of the whole region.