Sedimentology, petrography, hydraulic flow units, and reservoir quality of the bayhead delta reservoirs: Late Messinian Qawasim formation, Nile Delta, Egypt

摘要

Bayhead sandstone reservoirs are challenging due to their complexities and limited examples. This paper focused on the characteristics of the bayhead sandstone reservoirs and their heterogeneities based on an integrated sedimentological, petrographical, and petrophysical aspects that controls the exploration and development for these reservoirs. This study uses an example from Manzala Gas Field (Eastern Nile Delta). In this study, the sedimentological and petrographical analyses are employed to understand the internal textures and architecture as well as meso- and microscopic heterogeneities of the bayhead delta reservoirs. This is integrated with the petrophysical characteristics and neural network techniques to characterize hydraulic flow units of bayhead delta reservoir using core, borehole image, and log data. The bayhead delta (bay fill) reservoir consists of five main sedimentary sub-environments include main distributary channel, proximal and distal crevasse splays, and crevasse channels, as well as bayhead delta lobes. The distributary channel represents the highest reservoir quality (units 3 and 4), followed by crevasse channel (unit 3 and 2); bayhead delta front lobes (units 2 and 1), and the lowest quality crevasse splays (unit 1). On microscale, the bayhead delta reservoir is characterized by wide spectrum of lithofacies from quartz arenite to feldspathic wacke. The depositional setting is important controlling factor on the reservoir quality that altered by the diagenetic processes. They include the anhydrite, quartz, carbonate, and chlorite, and kaolinite cements as well as dissolution of quartz, feldspar, bioclast, and carbonate grains. This study enhances the understanding of the of the bayhead distributive system heterogeneities and prediction of bay fill facies reservoirs to improve the exploration and development of that targets.