Syn-Rift Deposition and Structural History of the B Trend, Southern Suez Rift, Egypt

By

 Joseph T. Piombino¹, Ivar Mundal¹, Ibrahim Hanbal²

(1) BP, Houston, TX (2) GUPCO, New Maadi - Cairo, Egypt

 The B trend is a complexly faulted NW-SE striking (rift-parallel) structural high in the southern Gulf of Suez, Egypt. It exhibits a complex structural and syn-rift depositional history. Miocene syn-rift rocks host 42% of the 398 million barrels of oil produced to date, necessitating an understanding of these reservoirs. Net sandstone and interval isopachs were generated for five syn-rift horizons, using over 200 wells, 65% with biostratigraphic control, allowing us to determine the structural evolution of the B Trend. The Early Miocene (pre-Aquitanian) erosion pattern reflects a mix of Late Cretaceous Syrian Arc (compressional) and Oligo-Miocene rift-parallel structural trends. Locally, the pre-rift section is deeply eroded, and several bald highs developed. The earliest syn-rift rocks of the Nukhul Formation were deposited in basins which were generally oblique to the rift-parallel trend. Nukhul isopach patterns suggest that the B Trend was not yet developed. Interval isopachs of the Burdigalian and Langhian Rudeis Formation reflect the emergence of the B Trend as a prominent high block. The isopach and subcrop patterns of the overlying Ayun Musa Formation illustrate significant thinning over the crest of most of the B Trend (with local exceptions). Locally, high blocks were extensively eroded after deposition of the Ayun Musa Formation, forming unconformities and supplying sediment to downthrown structural blocks. Sandstone thickness increases dramatically on these blocks, forming the basis of an untested play. Supercrop maps on the post-Ayun Musa unconformity and the isopachs of overlying units identify local persistent positive features.