A Multi-Process Reservoir Modelling Workflow as the Key for Unlocking Reservoir Prediction in Carbonates. Application to a Sector Model from the Albion R&D Project

In carbonate reservoirs, because of the diversity of geological processes involved in the reservoir construction, the extrapolation of properties directly from well data to reservoir model gridblocks may lead to poorly predictive reservoir properties and then production forecasts. This paper proposes a modelling workflow in which new tools from disruptive technologies are associated in order to produce reservoir models consistently with reservoir geological construction. The workflow combines the simulation of the depositional facies and their transformation after diagenesis overprint. Original depositional facies are carried out from SED-RES™, a stratigraphic forward modelling software that generates and transports carbonate sediments according to ecological conditions and wind-induced currents. Then GODIAG™, a lattice gas, reproduces the evolution of the properties of the sediment after it has been deposited. The diagenesis history can be multi-stage and can involve different kinds of physical and chemical reactions. This new workflow has been evaluated in the framework of the ALBION R&D Project dedicated to the study of the Barremian-Aptian rudist-rich carbonate platform from south France that is known as an analogue of the Kharaib and Shuaiba reservoirs (UAE). Thanks to its multi-scale and multi-site aspect, ALBION offers the opportunity to test new modelling tools. The efficiency of the new workflow has been successfully applied on a sector model from an ALBION site on which a rich geological and petrophysical dataset is available from outcrops and numerous wells,

Kutei Basin oil bearing sand reservoirs mapping using integrated seismic methods

The Lower Kutei Basin which contains several giant oil and gas fields is located on the East Kalimantan, Indonesia. This paper discusses the identification and mapping of oil-filled reservoirs and their depositional facies by integrating seismic stratigraphy, attributes, and AI (Acoustic Impedance) inversion methods. The log data cross-plots show that AI can be used to distinguish oil-sands from wet sands and shale, and to derive the total porosity of the sands. However, AI and amplitude values are greatly affected by the oil, porosity and tuning effects, hence they cannot be used to identify the facies containing the oil-bearing sands. Therefore, to map the facies containing the oil-filled sands, the AI map is combined with the variance and sweetness maps. It can be seen clearly from the variance and sweetness maps that the oil-sands suggested by the AI map are contained in a narrow and elongate meander-like geometry which is typical of channel facies. The variance and sweetness maps suggest that there are two channels in the study area. To determine which channel is thicker, spectral decomposition RGB map was made. The result suggests that the right channel is more prospective as it associates with thicker sand deposits. The combination of variance, sweetness and RGB maps strongly indicate that the channels in the study area are in upper-slope environment, and the thicker oil-sands are located in the eastward of the study area.

Fissure Ridges: A Reappraisal of Faulting and Travertine Deposition (Travitonics)

The mechanical discontinuities in the upper crust (i.e., faults and related fractures) lead to the uprising of geothermal fluids to the Earth’s surface. If fluids are enriched in Ca2+ and HCO3-, masses of CaCO3 (i.e., travertine deposits) can form mainly due to the CO2 leakage from the thermal waters. Among other things, fissure-ridge-type deposits are peculiar travertine bodies made of bedded carbonate that gently to steeply dip away from the apical part where a central fissure is located, corresponding to the fracture trace intersecting the substratum; these morpho-tectonic features are the most useful deposits for tectonic and paleoseismological investigation, as their development is contemporaneous with the activity of faults leading to the enhancement of permeability that serves to guarantee the circulation of fluids and their emergence. Therefore, the fissure ridge architecture sheds light on the interplay among fault activity, travertine deposition, and ridge evolution, providing key geo-chronologic constraints due to the fact that travertine can be dated by different radiometric methods. In recent years, studies dealing with travertine fissure ridges have been considerably improved to provide a large amount of information. In this paper, we report the state of the art of knowledge on this topic refining the literature data as well as adding original data, mainly focusing on the fissure ridge morphology, internal architecture, depositional facies, growth mechanisms, tectonic setting in which the fissure ridges develop, and advantages of using the fissure ridges for neotectonic and seismotectonic studies.

Brittlestar diversity at the dawn of the Jenkyns Event (early Toarcian Oceanic Anoxic Event): new microfossils from the Dudelange drill core, Luxembourg

Ophiuroids, the slender-armed cousins of starfish, which constitute an important component of modern marine benthos and have been used successfully in exploration of (palaeo)-ecological and evolutionary trends, yet their fossil record is still poorly known. One of the major gaps in the known palaeobiodiversity of this group coincides with a global palaeoenvironmental crisis during the early Toarcian (Early Jurassic, 183 myr ago), known as the Jenkyns Event. Here, we describe ophiuroid remains retrieved from a series of samples from the Dudelange (Luxembourg) drill core, which spans the lower part of the Toarcian, between the top of the Pliensbachian to the onset of the Jenkyns Event. A total of 21 species are recorded, including three new genera and 12 new species. Ophiuroid diversity and abundance fluctuate in parallel with depositional facies, with lowest values coinciding with black shales. Highest diversities, including exceptional occurrences of taxa nowadays restricted to deep-sea areas, are recorded from just below the black shales corresponding to the onset of the Jenkyns Event. Our results show that even small (100 g) bulk sediment samples retrieved from drill cores can yield numerous identifiable ophiuroid remains, thus unlocking this group for the study of faunal change across palaeoenvironmental crises.

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

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.