Integration of well logs and seismic data for facies analysis and modelling of the El-Wastani Formation in the Sequoia Gas Field, offshore Nile Delta, Egypt

Abstract

Reservoir rock facies modelling helps in determining the degree of reservoir variability for enhanced management of the heterologous facies’ reservoirs, both at borehole scale and more regionally at seismic scale. The Pliocene Offshore Sequoia Gas Field is located near the boundary between the Rosetta Concession and the West Delta Deep Marine Concession (WDDM) on the western side of the Nile Delta. It is characterised by canyon systems of complex turbidite channel-levee deposits that are multi-stacked. In order to create various depositional facies that are compatible with a deep marine environment, an advanced facies model was built from the combination of the seismic, core, and formation micro imager (FMI). Sandstones (laminated and massive), shale (laminated and massive mud-rock), silt, and thin sandstone beds were identified as four major facies. In the Sequoia field area, the El-Wastani Formation is known as a heterogeneous sequence of sandstones and mudstones arranged into a broad upward-fining succession. High-quality, blocky sands exist at the base, while the upper portion is characterised primarily by isolated sand bodies intercalated with mudstones in the presence of some thin-bedded sands (their thickness less than 1 m).