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This book is both a review and a look to the future, highlighting challenges for better predicting quantitatively the impact of diagenesis on reservoir rocks. Classical diagenesis studies make use of a wide range of descriptive analytical techniques to explain specific, relatively time-framed fluid-rock interaction processes, and deduce their impacts on reservoir rocks. Future operational workflows will consist of constructing a conceptual diagenesis model, quantifying the related diagenetic phases, and modelling the diagenetic processes. Innovative approaches are emerging for applied quantitative diagenesis, providing numerical data that can be used by reservoir engineers as entry (input) data, and for validating results of numerical simulations. Geometry-based, geostatistical and geochemical modelling do not necessarily mimic natural processes, they rather provide reasonable solutions to specific problems.

Diagenesis. --- Fossil fuels. --- Geochemistry. --- Geology, Economic. --- Geology --- Geotechnical engineering. --- Engineering, Geotechnical --- Geotechnics --- Geotechnology --- Engineering geology --- Geological statistics --- Geostatistics --- Economic geology --- Physical geology --- Mines and mineral resources --- Chemical composition of the earth --- Chemical geology --- Geological chemistry --- Geology, Chemical --- Chemistry --- Earth sciences --- Fossil energy --- Fuel --- Energy minerals --- Sedimentology --- Statistical methods. --- Economic geology. --- Fossil Fuels (incl. Carbon Capture). --- Quantitative Geology. --- Geotechnical Engineering & Applied Earth Sciences. --- Earth sciences. --- Earth Sciences. --- Economic Geology. --- Carbonate rocks. --- Rocks, Carbonate --- Carbonates --- Sedimentary rocks --- GeologyxMathematics. --- Geology, economic. --- Geology—Statistical methods. --- Diagenesis --- Fossil fuels --- Geochemistry --- Geology, Economic --- Geotechnical engineering --- Statistical methods

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The recent interest in the petroleum potential of Lebanon’s offshore and onshore geology have sparked a multitude of research projects. It is in this framework that the studies dealing with the potential of Qartaba Structure, a box-fold anticline in north-central Lebanon, are situated. The plateau of this anticline exposes large areas of the Jurassic Kesrouane Formation which have undergone 2 modes of dolomitization, i.e. an hypersaline flux and fracture-related hydrothermal dolomitization. Given the scarcity of information on the latter dolomites, a study that fills the gap in knowledge becomes a necessity. For this purpose, this thesis aims to provide new diagenetic data of these dolomites by providing a paragenetic model that links all observed facies, textures and pore types to the geologic evolution of the Kesrouane Formation. Besides the detailed fieldwork done and the five types of microscopes used, chemical and mineralogical techniques are employed to get more quantitative information on the internal properties of the dolomites. The obtained petrographic data indicate the occurrence of 2 limestone facies, 2 dolomite types, 5 different cements, 8 pore types, 5 veins types and at least 2 compaction features. During early diagenesis, limestones were deposited in a shallow marine environment followed by early mechanical compaction. Later during burial, dolomitization occurs and is strongly influenced by the precursor lithologies. Later, the system is uplifted and the oxic conditions are introduced. Chemical analyses indicate a non-ferroan nature of the dolomites and minor to negligible clay contents. Sodium contents likely correspond to the presence of saline fluid inclusions that formed during dolomitization. Mineralogical, combined with chemical data indicate a supply of Ca and Mg enough to yield a stoichiometric and ordered growth of the dolomite crystals. Saddle dolomites are slightly less ordered due to imperfect crystal growth and/or additional Ca in the crystal lattice. The pyrites observed in the field are explained by a 4-step conceptual model. Framboidal pyrites were formed by bacterial sulfate reduction in the eogenetic realm, but were later recrystallized and remobilized by the hydrothermal fluids. This would explain the occurrence of pyrites on the fringes of the dolomite bodies, which have been oxidized by groundwaters after exposure and uplift of the Qartaba structure. In the field, a trend of increasing crystal size towards the fault zones is observed. To explain this phenomenon, 3 possible processes are suggested but still need further validation. These processes deal with (i) the supply of Ca and Mg adjacent to the faults, (ii) the “cleaning effect” of basaltic materials associated with the faults and (iii) the importance of mechanical strength of the precursor lithologies on the propagation of faults. All the available data imply that dolomites, especially the sucrosic types offer interesting reservoir properties. They have good intercrystalline porosity and better pore connectivity than other dolomites. It is also important, when assessing reservoir porosity, to discard the pores triggered by recent karst-related dissolution. These results demonstrate the complexity of the hydrothermal dolomites and the difficulties in studying the distribution of their reservoir properties in natural analogues exposed at the surface.