Mohamed K. Zobaa

Depositional paleoenvironment and hydrocarbon source potential of the Oligocene Dabaa Formation, north Western Desert, Egypt: A palynofacies approach

A detailed palynofacies study was carried out on 24 shale cutting samples from the Oligocene Dabaa Formation, which was penetrated in the Amana-1X well, Abu El Gharadig Basin, north Western Desert, Egypt. The investigation targeted primarily three main groups of palynological elements: phytoclasts, palynomorphs, and amorphous marine organic matter (AMOM), using transmitted light microscopy. Two major marine palynofacies were recognized: the oldest is palynofacies 1, made up mainly of AMOM (average abundance 47.5%), phytoclasts (31.6%), and palynomorphs (20.9%). A suboxic to anoxic outer shelf to upper slope paleoenvironment is suggested for this palynofacies. Palynofacies 2 is characterized by poorly preserved translucent phytoclasts (average abundance 61.2%) in addition to palynomorphs (24%), AMOM (14.8%), and opaques (

Palynofacies Analysis and Submicron Pore Modeling of Shale-Gas Plays

The present study combines palynological applications with advanced microscopic techniques to characterize the Utica, Haynesville and Fayetteville shale-gas source rocks. This unprecedented approach could offer an alternative way to measure the total organic carbon (TOC) content using the 2D subsurface Scanning Electron Microscope (SEM) images. This approach is considered to be a faster and inexpensive method compared to conventional geochemical analyses. Palynofacies analysis provided valuable information about kerogen type and its degree of thermal maturation, which are key parameters in shalegas exploration. Moreover, it qualitatively allowed the estimation of important organic geochemical parameters such as vitrinite reflectance (Ro %) and numerical thermal alteration index (TAI). New high resolution microscopic solutions have successfully been exploited for source rock characterization at both microand nano-meter scales. In-situ Focused Ion Beam (FIB) and Scanning Electron Microscope (SEM) technologies provided new insights into rock fabrics such as porosity, permeability, tortuosity, anisotropy and kerogen content. Serial sectioning and sequential imaging using dual beam SEM/FIB instrument were implemented successfully to characterize the 2D kerogen content and 3D submicron-pore structures. Moreover, pores were found in organic matters with the size of nano level and occupy 40−50% of the kerogen body. A successful example of reconstructed 3D pore model from Fayetteville Shale is presented. Introduction Qualitative and quantitative characteristics of shale-gas source rock are used by petrophysicists, geochemists and reservoir engineers. These include submicron pore structure and organic matter analyses, which are important in the derivation of rock capillarity, wettability and storativity. Shale-gas source rocks hold large quantities of hydrocarbon reserves that have made significant impact on North American oil and gas market since early 2000s. The ambiguity behind gas storativity and deliverability can be demystified through the understanding of the relationship between organic matter content and porosity. Conventional standalone analyses are inadequate and not suited for unconventional gas rock characterization. The proposed combined approach provides important information for evaluating and appraising shale-gas plays. Palynofacies analysis identifies intervals of exploratory interest in terms of hydrocarbon content. It can also be used as a proxy to estimate organic geochemical values that are very expensive to obtain and thus, significantly reduces exploration and production costs. Pore imaging and modeling allows the evaluation of gas storage quantity and deliverability in shale-gas plays, which enables the development of optimized processes for hydrocarbon recovery. Palynofacies analysis as defined by Tyson (1995) is: “the palynological study of depositional environments and hydrocarbon source rock potential based upon the total assemblage of particulate organic matter.” In the present study, palynofacies analysis was carried out on five samples recovered from the Haynesville, Utica and Fayetteville shale-gas source rocks in order to evaluate their kerogen type and degree of thermal maturation. Three of the five studied samples are from the Utica Shale (two samples from Dolgeville member and one sample from the Indian Castle Member), while the fourth and fifth samples are from Haynesville and Fayetteville shales. The data obtained were used to qualitatively estimate some key organic geochemical parameters such as vitrinite reflectance (Ro %) and numerical thermal alteration index (TAI). Samples were also analyzed for TOC content in order to fully understand their source potential.

A review of the angiosperm pollen genus Cretacaeiporites Herngreen, with one new species from the Upper Cretaceous of Egypt

An emended diagnosis of the angiosperm pollen genus Cretacaeiporites is proposed to encompass all attributed species. A comprehensive review of all Cretacaeiporites species is also given with the description of C. aegyptiaca sp. nov. from the subsurface mid-Cretaceous (Bahariya Formation) of northwest Egypt. A new combination, C. krutzschi (Boltenhagen) comb. nov., is also proposed. The review includes the original diagnosis of each taxon, holotype line illustrations and remarks on how to differentiate them from each other, in addition to a compilation of their known stratigraphical range and occurrences based on an exhaustive survey of their previous records.

The magnificent seven: the stratigraphically most important mid-Cretaceous terrestrial palynofloral species in the north Western Desert, Egypt

IntroductionThis paper presents the essential taxonomic information needed to easily identify seven of the stratigraphically most important terrestrial palynofloral species in dating the subsurface mid-Cretaceous strata in the north Western Desert of Egypt. It synthesizes decades of palynological work on such economically important rock sequences in the southeast Mediterranean. The seven species, Crybelosporites pannuceus, Elaterocolpites castelainii, Elateroplicites africaensis, Elaterosporites klaszii, Afropollis jardinus, Cretacaeiporites densimurus, and Reyrea polymorphus have long been used by many authors to define biostratigraphic zonations for the mid-Cretaceous sedimentary sequences in Egypt.MethodsA comprehensive taxonomic overview that includes ample details and clear illustrations has been compiled. In addition to the original description of the seven species and their genera, an attempt has also been made to provide additional explanations in simplified taxonomic terminology.ConclusionsThis paper provides novice palynologists the tool to understand and recognize the key identification features of each species in a more timely manner instead of going through old, mostly hard to find, literature.ResumenIntroducciónEl presente trabajo muestra la información taxonómica esencial para la identificación de 7 de las especies palinológicas continentales más importantes para la datación en sondeos del Cretácico medio del NW del desierto de Egipto. Este trabajo sintetiza décadas de investigación llevados a cabo en estas secuencias de importante interés económico del SE del Mediterráneo. Estas siete especies, que han sido utilizadas por muchos autores para definir zonaciones bioestratigráficas son: Crybelosporites pannuceus, Elaterocolpites castelainii, Elateroplicites africaensis, Elaterosporites klaszii, Afropollis jardinus, Cretacaeiporites densimurus, and Reyrea polymorphus.MétodoSe ha realizado una revisión taxonómica de fácil comprensión y con claras ilustraciones. Además de la descripción general de las siete especies, se ha realizado una explicación simplificada de la terminología taxonómica.ConclusionesEste trabajo proporciona una nueva herramienta para entender y reconocer las principales características de identificación de las especies de una manera sencilla evitando otros medios que presentan una mayor dificultad.

Palynological evidence for sustained deep-marine conditions during the Eocene–Miocene in the southern Gulf of Mexico distal continental margin

The present study represents the first attempt to provide palynological data about the southern Gulf of Mexico distal continental margin during the Eocene−Miocene time interval. In addition to documenting the types of fossil palynomorphs preserved in these economically critical rock sequences, this study also provides important information about the accumulation and preservation of total sedimentary particulate organic matter along with their paleoenvironmental and paleoceanographic implications. This was accomplished through the analysis of cored sediments from the Deep Sea Drilling Project Site 94 north of the Yucatan Peninsula and Site 540 south of the Western Florida Escarpment. The present findings from the deep waters of southern Gulf of Mexico are expected to greatly assist hydrocarbon geoscientists in their exploration and development efforts, reducing investment risk and drilling uncertainty. Two palynofacies assemblages were recognized based on particulate organic matter analysis: marine-dominated palynofacies A and terrestrially influenced palynofacies B. The organic compositions of these two palynofacies along with the recovered dinoflagellate cyst community suggest that while sustained oceanic depositional conditions were prevalent, occasional influxes of terrestrial organic material of variable magnitudes occurred. These short-term influxes were especially pronounced during the late Eocene and earliest Oligocene and appear to have happened in response to the cooling and slight global sea-level drop that occurred at ca. 38−33.5 Ma. The preserved terrestrial palynomorphs in the samples indicate coastal plain and estuarine vegetation sources in general, except during the Eocene-Oligocene transition, when anemophilous pollen specimens mostly derived from farther inland and montane sources were recovered.