Delineation of an inversion structure of Upper Jurassic-Lower Cretaceous succession based on interpretation of seismic data of Alamein oil field, Northern Western Desert, Egypt

Abstract

This study aims to evaluate an inversion structure and detailed structural elements based on a set of 2D seismic lines at Alamein oil field. A 3D structural model has been built, tied with drilled wells and picked horizons, to display the different structural elements controlling main various horizons of Alamein field. The belts movement causes a regional extensional regime during the Jurassic and Early Cretaceous period then followed by a stress movement at the Late Cretaceous – Oligocene period that formed the Alamein inversion. Alamein oil field is characterized by a positive inversion structure caused by the Jurassic-Early Cretaceous master inverted fault. This inverted fault is situated in the central part of Alamein field bounding a half-graben trough accompanied with gradual subsidence toward the southeastern part of the study area with a continued deposition of the lower Cretaceous sediments. Alamein field represents a nearly E-W asymmetrical anticline overlying the Late Jurassic- Early Cretaceous and dissected by a large number of NW-SE faults which mainly died-out in Lower Cretaceous and rare of them passed to deepest level (Jurassic period). In the beginning of Jurassic time, many faults of ENE-WSW direction are detected and maybe initiated from Pre-Jurassic and extended to the younger levels due to movement of belts.