High-Resolution Stratigraphy and Sedimentology of Upper Khartam Member of the Permo-Triassic Khuff Formation; Outcrop Reservoir Analog Approach From Central Saudi Arabia

Abstract

The Permian-Triassic Khuff reservoirs of the Middle East are estimated to contain about 15–20% of the world's gas reserves. These reservoirs have unique outcrop equivalent exposed in Central Saudi Arabia. Several outcrop sections of Khartam member were investigated in details where stratal stacking patterns were examined to construct a high-resolution stratigraphic scheme. Furthermore, beds were followed lateral for a distance of 200 – 1400 m to establish composite sedimentological logs. As a result, about 32 sequences were described; these are consistence with the previously defined depositional sequences of the Upper Khartam member. The defined parasequences composed of at least two interbedded beds of the following lithofacies, gypsum, fissiled mudstone, massive mudstone, thinly laminated mudstone, sigmoidal cross-laminated mudstone, fenestral to flaser cross-laminated mudstone; massive oolitic grainstone; fossiliferous oolitic grainstone; cross-bedded oolitic grainstone (e.g., trough, herringbone, sigmoidal, fenestral, flaser, and crimpling). Bifurcations, imbricates, pinching-out, merging, stylolites, and symmetrical wave-ripples were observed in some of the studied beds. The studied stratal patterns and lithofacies are the association of lagoonal, supratidal, intertidal, subtidal, and possibly eolian beach environments. The presented results could enhance the understanding and prediction of the Khuff reservoirs quality and architecture of the Middle East. Additionally the followed methodology will bring new insight in characterizing carbonate reservoir heterogeneities.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015