Jerry A. Nott1, J. Larry Gibson1, R. Craig Shipp1
(1) Shell International E&P, Inc, Houston, TX
ABSTRACT: Near-Surface Depositional Framework of the Northeastern Mediterranean (NEMED) Concession Area, Deepwater Egypt
The near-surface section of a large 3-D survey (7000 km2) seaward of the Nile Delta in the southeastern Mediterranean Sea was investigated for the assessment of potential hazards to exploratory drilling in a frontier deepwater basin. Another dimension of this investigation afforded a unique opportunity to undertake a high-resolution study of a complex regional framework in contrasting stable versus structurally active settings. Thickness of Upper Miocene (Messinian) evaporites subdivides the NEMED area into a stable platform area in the west (evaporites thin or absent) and a salt diapir province in the east, where thick salt deposits led to formation of minibasins under the Plio-Pleistocene sedimentary load. The stable western platform is characterized by a highly channelized, high-amplitude reflection package in the near subsurface section (upper 500-600 ms). This interval may be sand-prone and locally gas-charged. In areas where water depth exceeds 1800 m, the presence of a bottom-simulating reflector (BSR) suggests the possible presence of hydrates, associated with this high-amplitude reflection package. The less stable eastern diapiric salt minibasins are characterized by onlapping, high-amplitude reflection packages interpreted as ponded slope fans, with bypass-channel complexes at the top of each fan. Near-surface assessment of a poorly calibrated deepwater frontier basin provides a much improved understanding of the impact of potential drilling hazards over a site investigation of the prospect area only. This approach assures identification of several types of hazards unique to deepwater, which are not easily identified at the site-survey scale. Also, an added benefit of near-surface regional assessment is to provide potential depositional analogs for the deeper subsurface section. A geologic model based on the near-surface section, where data quality, continuity, and frequency are generally superior, can also contribute to better understanding of the framework and prospectivity of the deeper section.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado