Multi-disciplinary approach to sedimentary facies analysis of Messinian Salinity Crisis tectono-sequences (South-Mansoura Area, Nile Delta): Incised-valley fill geological model reconstruction and petroleum geology–reservoir element delineation

Abstract

The quality of a hydrocarbon reservoir is strongly controlled by the depositional and diagenetic facies nature of the given rock. Therefore, building a precise geological/depositional model of the reservoir rock is critical to reducing risks while exploring for petroleum. Ultimate reservoir characterization for constructing an adequate geological model is still challenging due to the in general insufficiency of data; particularly integrating them through combined approaches. In this paper, we integrated seismic geomorphology, sequence stratigraphy, and sedimentology, to efficiently characterize the Upper Miocene, incised-valley fill, Abu Madi Formation at South Mansoura Area (Onshore Nile Delta, Egypt). Abu Madi Formation, in the study area, is a SW-NE trending reservoir fairway consisting of alternative sequences of shales and channel-fill sandstones, of the Messinian age, that were built as a result of the River Nile sediment supply upon the Messinian Salinity Crisis. Hence, it comprises a range of continental to coastal depositional facies. We utilized dataset including seismic data, complete set of well logs, and core samples. We performed seismic attribute analysis, particularly spectral decomposition, over stratal slices to outline the geometry of the incised-valley fill. Moreover, well log analysis was done to distinguish different facies and lithofacies associations, and define their paleo-depositional environments; a preceding further look was given to the well log-based sequence stratigraphic setting as well. Furthermore, mineralogical composition and post-depositional diagenesis were identified performing petrographical analysis of some thin sections adopted from the core samples. A linkage between such approaches, performed in this study, and their impact on reservoir quality determination was aimed to shed light on a successful integrated reservoir characterization, capable of giving a robust insight into the depositional facies, and the associated petroleum potential. The results show that MSC Abu Madi Formation constitutes a third-order depositional sequence of fluvial to estuarine units, infilling the Eonile-canyon, with five sedimentary facies associations; overbank mud, fluvial channel complex, estuarine mud, tidal channels, and tidal bars; trending SW-NE with a Y-shape channel geometry. The fluvial facies association (zone 1 and 3) enriches coarse-grained sandstones, deposited in subaerial setting, with significantly higher reservoir quality, acting as the best reservoir facies of the area. Although the dissolution of detrital components, mainly feldspars, enhanced a secondary porosity, improving reservoir quality of MSC Abu Madi sediments, continental fluvial channel facies represent the main fluid flow conduits, where marine influence is limited.

Focused reservoir characterization: analysis of selected sand units using well log and 3-D seismic data in 'Kukih' field, Onshore Niger Delta, Nigeria

“…The intricate patterns manifested within well logs served as the springboard for establishing the stratigraphic framework and deciphering the trends associated with the lateral continuity prevalent within the field. Intriguingly, the GR (Gamma-ray) curve pattern emerged as an instrument for expounding the depositional environments 25 . Within this context, distinctive curve shapes unfold the Cylindrical shape, marked by minimal GR values, distinct sharp boundaries, and a notable absence of trends; the Bell-shaped, epitomizing an upward augmentation in GR values; and finally the Funnel-shaped, characterized by an ascending decrease in GR values coupled with a coarsening upward succession.…”

“…The intricate patterns manifested within well logs served as the springboard for establishing the stratigraphic framework and deciphering the trends associated with the lateral continuity prevalent within the field. Intriguingly, the GR (Gamma-ray) curve pattern emerged as an instrument for expounding the depositional environments 25 . Within this context, distinctive curve shapes…”

Analysis of the Efficiency of Petroleum Systems in Fluvial Environments in the Rift Context of the South and North Atlantic: Brazil and Portugal

“…The identification of post-depositional diagenetic processes is of paramount importance in the characterization of reservoirs, as they directly affect their porosity and permeability parameters, and, consequently, their performance in hydrocarbon recovery [37]. Several diagenetic processes affected the Sergi Formation sandstones, causing important changes in their porosity and permeability, and introducing significant heterogeneities that added to the depositional heterogeneities [38].…”

“…Geosciences 2023, 13, x FOR PEER REVIEW 20 of 34 permeability parameters, and, consequently, their performance in hydrocarbon recovery [37]. Several diagenetic processes affected the Sergi Formation sandstones, causing important changes in their porosity and permeability, and introducing significant heterogeneities that added to the depositional heterogeneities [38].…”