Petrophysical and petrographical delineation for carbonate reservoir rocks in north Western Desert, Egypt

Abstract

Carbonate rocks hold considerable volumes of hydrocarbons in various basins around the globe. Understanding the complex pore systems is a key factor in unlocking the potential of carbonate rocks. Matrix properties are also a challenge in carbonate reservoirs. Exploration geoscientists include the regional portfolio targeting the sweet spots for every basin. This study defines the reservoir quality and character of carbonate rocks with scope to the complete carbonate succession of north Western Desert and Abu Gharadig basin (AGB) as one of the most prolific basins in Egypt. More than 301 core samples are used in this study to represent all carbonate rock types. The workflow includes core data classification (grouping), petrographical investigation, reservoir mineralogy, and matrix parameters integrated with well logs and elastic properties. The provided work investigates the effect of pore structure and mineralogy on the petrophysical properties of the rock and its impact on elastic properties as well. Carbonate reservoirs in AGB are divided into three main categories: type-I, type-II, and type-III. Reservoirs enhancement by dolomitization and dissolution are controlling the distribution of pores, which are the key factors to delineate their potential. This study defines the characteristics of each group and the attractive formations for future exploration and development. The main differences in rock type, composition, diagenetic processes, and elastic properties were described. The rock brittleness index was calculated from dynamic properties for each carbonate type to get more insights about the rock brittleness and elasticity and predict variations of each group for future consideration in the basin.