Contribution to the understanding of the Ionian Basin sedimentary evolution along the eastern edge of Apulia during the Late Cretaceous in Albania

Integrated in the peri-Adriatic domain, the Ionian Basin extended along a NW-SE direction during the Late Cretaceous, limited on its sides by the Apulian and the Kruja platforms. The basinal/slope succession was studied in seven outcrops exposed in the Albanian fold-and-thrust belt. Sedimentological investigations, supported by bio- and chronostratigraphy were performed on calcareous Upper Cretaceous hemipelagites, gravity-flow deposits and slumps. The western part of the basin was studied, revealing a strong influence of the Apulian margin, alternatively shedding sediment basinward, by means of a tectonically controlled edge. The Late Albian to Cenomanian period is characterized by the settling of muddy debrites along the margin. A deep basinal environment characterizes this period which prolongs until the Santonian, with no significant influx of the platform basinward. This sedimentary setting abruptly changed at the end of the Santonian, with an important influx derived from both platforms. Coarsening and thickening upward sequences show a progressive increase in sediment shedding during the Campanian. The Late Campanian-Early Maastrichtian period points out a major change on the resedimentation processes with the settling of several slumped units reworking thick sediment packages. The latter can be traced along the Apulian margin, testifying of instabilities along the edge of Apulia

Changes in composition and pore space of sand rocks in the oil water contact zone (section YU[1] {3-4}, Klyuchevskaya area, Tomsk region)

The article provides an analysis of specific features in changes of rocks in the oil water contact zone. The object of study is the formation YU[1] {3-4} (J[3]o[1]) of Klyuchevskaya oil deposit (West Siberian oil-gas province, Tomsk region). The research data allow the authors to determine vertical zoning of the surface structure and identify the following zones: oil saturation (weak alteration), bitumen-content dissolution, non-bitumen-content dissolution, cementation, including rocks not affected by hydrocarbon deposit. The rocks under investigation are characterized by different changes in composition, pore space, as well as reservoir filtration and volumetric parameters. Detection of irregularity in distribution of void- pore space in oil-water contact zones is of great practical importance. It helps to avoid the errors in differential pressure drawdown and explain the origin of low-resistivity collectors

Méthode d’évaluation quantitative de l’hétérogénéité de la fracturation dans les carrières souterraines de calcaire à astéries

Durant ces dix dernières années, l’analyse quantitative de l’hétérogénéité de la fracturation par le Système d’information géographique (SIG) devient intéressante pour étudier la stabilité des carrières souterraines et des propriétés réservoirs induites par la fracturation et ses relations avec les écoulements souterrains. Cet article propose une méthode d’analyse quantitative de la fracturation du calcaire en carrières souterraines. Plus de 1 000 fractures dans trois carrières souterraines carbonatées ont été relevées, mesurées, cartographiées et numérisées. L’analyse de l’hétérogénéité et de la connexité de la fracturation est fondée sur la répartition spatiale des paramètres géométriques de chaque fracture, tels que : ouverture, longueur, direction, orientation, écartement et distribution spatiale des familles de fractures

Zn(II), Mn(II) and Sr(II) Behavior in a Natural Carbonate Reservoir System. Part I: Impact of Salinity, Initial pH and Initial Zn(II) Concentration in Atmospheric Conditions

The sorption of inorganic elements on carbonate minerals is well known in strictly controlled conditions which limit the impact of other phenomena such as dissolution and/or precipitation. In this study, we evidence the behavior of Zn(II) (initially in solution) and two trace elements, Mn(II) and Sr(II) (released by carbonate dissolution) in the context of a leakage from a CO2 storage site. The initial pH chosen are either equal to the pH of the water-CO2 equilibrium (~ 2.98) or equal to the pH of the water-CO2-calcite system (~ 4.8) in CO2 storage conditions. From this initial influx of liquid, saturated or not with respect to calcite, the batch experiments evolve freely to their equilibrium, as it would occur in a natural context after a perturbation. The batch experiments are carried out on two natural carbonates (from Lavoux and St-Emilion) with PCO2 = 10−3.5 bar, with different initial conditions ([Zn(II)]i from 10−4 to 10−6 M, either with pure water or 100 g/L NaCl brine). The equilibrium regarding calcite dissolution is confirmed in all experiments, while the zinc sorption evidenced does not always correspond to the two-step mechanism described in the literature. A preferential sorption of about 10% of the concentration is evidenced for Mn(II) in aqueous experiments, while Sr(II) is more sorbed in saline conditions. This study also shows that this preferential sorption, depending on the salinity, is independent of the natural carbonate considered. Then, the simulations carried out with PHREEQC show that experiments and simulations match well concerning the equilibrium of dissolution and the sole zinc sorption, with log KZn(II) ~ 2 in pure water and close to 4 in high salinity conditions. When the simulations were possible, the log K values for Mn(II) and Sr(II) were much different from those in the literature obtained by sorption in controlled conditions. It is shown that a new conceptual model regarding multiple Trace Elements (TE) sorption is required, to enable us to better understand the fate of contaminants in natural systems

Zn(II), Mn(II) and Sr(II) Behavior in a Natural Carbonate Reservoir System. Part II: Impact of Geological CO

Some key points still prevent the full development of geological carbon sequestration in underground formations, especially concerning the assessment of the integrity of such storage. Indeed, the consequences of gas injection on chemistry and petrophysical properties are still much discussed in the scientific community, and are still not well known at either laboratory or field scale. In this article, the results of an experimental study about the mobilization of Trace Elements (TE) during CO2 injection in a reservoir are presented. The experimental conditions range from typical storage formation conditions (90 bar, supercritical CO2) to shallower conditions (60 and 30 bar, CO2 as gas phase), and consider the dissolution of the two carbonates, coupled with the sorption of an initial concentration of 10−5 M of Zn(II), and the consequent release in solution of Mn(II) and Sr(II). The investigation goes beyond the sole behavior of TE in the storage conditions: it presents the specific behavior of each element with respect to the pressure and the natural carbonate considered, showing that different equilibrium concentrations are to be expected if a fluid with a given concentration of TE leaks to an upper formation. Even though sorption is evidenced, it does not balance the amount of TE released by the dissolution process. The increase in porosity is clearly evidenced as a linear function of the CO2 pressure imposed for the St-Emilion carbonate. For the Lavoux carbonate, this trend is not confirmed by the 90 bar experiment. A preferential dissolution of the bigger family of pores from the preexisting porosity is observed in one of the samples (Lavoux carbonate) while the second one (St-Emilion carbonate) presents a newly-formed family of pores. Both reacted samples evidence that the pore network evolves toward a tubular network type

Contribution to the understanding of the Ionian Basin sedimentary evolution along the eastern edge of Apulia during the Late Cretaceous in Albania

Integrated in the peri-Adriatic domain, the Ionian Basin extended along a NW-SE direction during the Late Cretaceous, limited on its sides by the Apulian and the Kruja platforms. The basinal/slope succession was studied in seven outcrops exposed in the Albanian fold-and-thrust belt. Sedimentological investigations, supported by bio- and chronostratigraphy were performed on calcareous Upper Cretaceous hemipelagites, gravity-flow deposits and slumps. The western part of the basin was studied, revealing a strong influence of the Apulianmargin, alternatively shedding sediment basinward, by means of a tectonically controlled edge. The Late Albian to Cenomanian period is characterized by the settling of muddy debrites along themargin. A deep basinal environment characterizes this period which prolongs until the Santonian, with no significant influx of the platform basinward. This sedimentary setting abruptly changed at the end of the Santonian, with an important influx derived from both platforms. Coarsening and thickening upward sequences show a progressive increase in sediment shedding during the Campanian. The Late Campanian-Early Maastrichtian period points out a major change on the resedimentation processes with the settling of several slumped units reworking thick sediment packages. The latter can be traced along the Apulian margin, testifying of instabilities along the edge of Apulia.status: publishe

Meter-scale cycles as a proxy for the evolution of the Apulian Carbonate Platform during the late Cretaceous (Llogara Pass, Albania)

© 2015, Springer-Verlag Berlin Heidelberg. Sedimentological investigations have revealed ten facies in Upper Cretaceous platform carbonates (1220 m thick) at Llogara Pass in southern Albania that can be grouped into four facies associations. These reflect specific environmental conditions, ranging from intertidal to subtidal. The facies form small-scale patterns attesting to high-frequency/low-amplitude cyclicity characteristic of relative sea-level fluctuations. Meter-scale cycles have been classified into six distinct types and characterized on the basis of diagnostic surfaces, diagenetic features, and reservoir properties. A closer look at diagenetic and petrophysical features revealed a drastic porosity reduction at each cycle top (i.e., cycle boundary). This underlines a strong interconnection of facies types and reservoir properties at the cycle scale, thus impacting the whole carbonate succession. The cycle stacking pattern is a reflection of the sedimentary evolution during the late Cretaceous in this southern part of the Apulian Platform. (1) Meter-scale peritidal cycles suggest that the Cenomanian was characterized by stable shallow-water conditions. (2) Thick stromatolitic-dominated cycles typify Turonian deposits. Although the nature of the deposits indicates inner platform conditions, the long-term hiatus documented from Italy (Turonian bauxites) is not evidenced in Llogara. (3) The thin (a few tens of meters) Coniacian–Santonian interval suggests the onset of a significant tectonic control over the sedimentary dynamics, likely accompanied by morphological changes on the Apulian Platform and an emergence of rudist-dominated cycles. (4) Peritidal-subtidal cycles persist during the Campanian, accompanied by a broad development of rudist organisms that evidence significant and repeated relative sea-level rise. These data allow refinement of the general sedimentological evolution during the late Cretaceous on the Apulian Platform.status: publishe

The dismantling of the Apulian carbonate platform during the late Campanian – early Maastrichtian in Albania

© 2018 Elsevier Ltd The Apulian carbonate margin is widely preserved across the Adriatic domain and has been extensively studied in the south of Italy. In Albania, Oligocene–Pliocene fold-and-thrust tectonics led to widespread exposure of the Apulian Platform and associated Ionian Basin carbonates. However, the portion linking the platform to the basin is missing, preventing a direct reconstruction of the platform margin. Syn-sedimentary folding and faulting are recognized in the uppermost part of both the platform and basinal/slope series. Mass transport deposits (MTDs) occur within the platform succession incorporated into well-bedded intertidal (stromatolites) to shallow-subtidal (rudist packstones) sedimentary sequences. They display significant lateral variability which is accompanied by both rigid and soft deformation structures. Spectacular slumps made up of sediment density flow deposits are recognized in the adjacent Ionian Basin. The lateral extent of basal shear surfaces, syn-sedimentary faults and folds evidenced in the Ionian Basin points toward multiple regional tectonic triggering events affecting the Apulian Platform margin at that time. Bio- and chrono-stratigraphic analyses suggest that the triggers occurred during the late Campanian – early Maastrichtian. Beyond the obvious interest from a stratigraphic point of view, the study of these events recording the dismantling of the Apulian carbonate platform allows for a better understanding of the triggering mechanisms and the sedimentary characteristics of MTDs and slumps at a basinal scale.status: publishe

The dismantling of the Apulian carbonate platform during the late Campanian – early Maastrichtian in Albania

The Apulian carbonate margin is widely preserved across the Adriatic domain and has been extensively studied in the south of Italy. In Albania, Oligocene–Pliocene fold-and-thrust tectonics led to widespread exposure of the Apulian Platform and associated Ionian Basin carbonates. However, the portion linking the platform to the basin is missing, preventing a direct reconstruction of the platform margin. Syn-sedimentary folding and faulting are recognized in the uppermost part of both the platform and basinal/slope series. Mass transport deposits (MTDs) occur within the platform succession incorporated into well-bedded intertidal (stromatolites) to shallow-subtidal (rudist packstones) sedimentary sequences. They display significant lateral variability which is accompanied by both rigid and soft deformation structures. Spectacular slumps made up of sediment density flow deposits are recognized in the adjacent Ionian Basin. The lateral extent of basal shear surfaces, syn-sedimentary faults and folds evidenced in the Ionian Basin points toward multiple regional tectonic triggering events affecting the Apulian Platform margin at that time. Bio- and chrono-stratigraphic analyses suggest that the triggers occurred during the late Campanian – early Maastrichtian. Beyond the obvious interest from a stratigraphic point of view, the study of these events recording the dismantling of the Apulian carbonate platform allows for a better understanding of the triggering mechanisms and the sedimentary characteristics of MTDs and slumps at a basinal scale

Induced Polarization of Carbonates

International audienceComplex conductivity measurements of carbonate rocks are scarce despite the occurrence of these rocks at the surface of the Earth. The complex conductivity spectra of 57 carbonate samples were measured in a broad frequency range and at four salinities (NaCl). A simple model of induced polarization is developed to be applied to induced polarization measurements in the field. The in-phase conductivity (related to conduction) is reported as a function of the pore water conductivity to determine the (intrinsic) formation factor and the surface conductivity. The surface conductivity and the normalized chargeability are linearly correlated to the specific surface area divided by the tortuosity of the pore space. This observation is consistent with a dynamic Stern layer polarization model, the Stern layer being the inner layer of the electrical double layer coating the grains. The quadrature conductivity is observed to be proportional to the measured normalized chargeability in agreement with the prediction of the constant phase model. The effect of the texture is discussed and we observe a power-law relationship between the permeability and the formation factor. Then, we illustrate how this model can be applied to field data performed over a carbonate syncline in the French Alps. A 1.9 km long profile is used to separate the glacial till infilling the depression from the underlying limestones in terms of induced polarization properties. The induced polarization survey allows imaging the water content and the specific surface area of the formations down to a depth of 220 m