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Adams, Roy D.1, A.G. Al-Dhubeeb1, M. M. Al-Khalid1, N. S. Alnaji1, G. Wyn ap G. Hughes1, R. L. Lindsay1
(1) Saudi Aramco, Dhahran, Saudi Arabia

ABSTRACT: Outcrop Analog for Lateral and Vertical Reservoir Heterogeneity in the Late Jurassic-Age Hanifa Formation, Saudi Arabia

During the Oxfordian, a broad, shallow carbonate shelf with intra-shelf basins occupied the Arabian Plate. Deposition of the Hanifa Formation, bounded below by the Tuwaiq Mountain Formation and above by the Jubaila Formation, took place in this setting, with regional variations in overall thickness and gross depositional setting influenced by broad infra-plate, structural flexures. The Hanifa is productive in the subsurface and includes the recent discovery of the Yabrin Field.
In addition to an extensive repository of subsurface data, the Hanifa Formation crops out along the Tuwaiq Escarpment in east-central Saudi Arabia, allowing collection of detailed surface observations and providing opportunities for drilling of shallow cores. West and south of Riyadh, the escarpment is readily accessible and extensive roadcuts complement outcrops along the face of the escarpment and on the sides of wadis. This combination of escarpment exposures, wadi outcrops, roadcuts, and shallow core provides opportunities for 3-D descriptions of lateral and vertical heterogeneities at scales ranging from tens of meters to kilometers.
A preliminary, integrated dataset consisting of two outcrop sections, photomosaics, and a shallow core form the apices of a triangle with sides of 22- to 27-km in length. Data collected and correlated from core and stratigraphic sections include depositional facies, biofacies, petrography, and biostratigraphy and help document kilometer-scale lateral and vertical heterogeneities. Photomosaics provide documentation of localized (meter-scale) lateral and vertical heterogeneities. Preliminary analysis of this integrated data set documents lateral and vertical changes in cycle thickness and depositional facies at scales of tens of meters and kilometers.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.