Core Lithofacies Analysis of Reservoir Interval (Albian—Cenomanian) Bentiu Formation of SE Muglad Basin, Sudan

Abstract

This study presents the analysis of lithofacies of the subsurface reservoir horizon of Bentiu Formation (Late Albian—Cenomanian) from the SE Muglad basin in Sudan. A detailed core description to analyze and study the different lithofacies, facies association, and architectural elements and to infer the depositional environment is conducted. The study reveals the presence of seven sedimentary lithofacies (massive sandstone, horizontal or parallel-laminated sandstone, planar cross-laminated sandstone, trough cross-laminated sandstone, ripple-laminated sandstone mudstone and sandy mudstone, and conglomerate.) they can be grouped into two major facies as sandstones and conglomerates, and one minor mudstone and sandy mudstone facies. These facies are grouped into five facies associations, which represent the elements of fluvial depositional systems. They can be distinguished from their different stacking patterns. Sandstone which is ranging in grain size from fine to coarse is characterized by massive, cross-laminated, ripple-laminated, parallel-laminated structures, and some bioturbation sedimentary features. These sandstones are also characterized by fining-upward sequence indicating fluvial braided stream depositional environment.