Euzen, Tristan¹, R. Eschard¹, O. Lerat¹, R. Deschamps¹, E. Albouy¹
(1) Institut Français du Pétrole, 92852 Rueil Malmaison Cedex, France

ABSTRACT: Three-Dimensional Modelling of a Turbidite Channel Complex from Outcrop Restoration (Pab Formation, Pakistan)

The Upper Maastrichtian Pab turbidite system crops out in the Kirthar fold belt in Western Pakistan, and was deposited in a passive margin setting, on the NW border of the Indo-Pakistani plate. The lower part of this system is a sand-rich basin floor fan fed by a canyon eroding the shelf and the slope. Three successive channel complexes separated by extensive hemipelagite deposits have been identified.
These channel complexes consist of several individual channels stacked vertically or migrating laterally depending on the local confinement. During erosional stage of individual channels, by-pass facies (mud-clast lags, thin-bedded draping, monogenic debris flow) and overflow deposits (levees and crevasse lobes) were deposited. Channel was then filled with thick, massive to laminated sandstone. Finally, tabular extensive spillover lobes capped the channel.
The stratigraphic architecture of the uppermost channel complex of the basin floor fan was reconstructed at reservoir scale, using interpreted outcrop photo-panels restored in three dimensions. The methodology includes a deterministic approach for the construction of surfaces bounding individual channels and both deterministic and stochastic approaches for the simulation of lithofacies volumes. The resulting static model allows visualising and quantifying in three dimensions the small-scale internal heterogeneity of the channel complex. Such small-scale heterogeneity may have major influence on the flow behaviour in equivalent subsurface reservoirs (offshore West African and Brazilian fields). Synthetic seismic, well test and dynamic modelling will be perform on this analogue model in order to characterise the sub-surface response of such reservoir heterogeneity.

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