Physical properties of seismogenic Triassic evaporites in the northern Appennines (Central Italy)

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Tectonic control on the petrophysical properties of foredeep sandstone in the Central Apennines, Italy

Petrophysical properties of rocks and their applicability at larger scale are a challenging topic in Earth sciences. Petrophysical properties of rocks are severely affected by boundary conditions, rock fabric/microstructure, and tectonics that require a multiscale approach to be properly defined. Here we (1) report laboratory measurements of density, porosity, permeability, and P wave velocities at increasing confining pressure conducted on Miocene foredeep sandstones (Frosinone Formation); (2) compare the laboratory results with larger-scale geophysical investigations; and (3) discuss the effect of thrusting on the properties of sandstones. At ambient pressure, laboratory porosity varied from 2.2% to 13.8% and P wave velocities (Vp) from 1.5 km/s to 2.7 km/s. The P wave velocity increased with confining pressure, reaching between 3.3 km/s and 4.7 km/s at 100 MPa. In situ Vp profiles, measured using sonic logs, matched the ultrasonic laboratory measurement well. The permeability varied between 1.4 × 10 15m2 and 3.9 × 10 15m2 and was positively correlated with porosity. The porosity and permeability of samples taken at various distances to the Olevano–Antrodoco fault plane progressively decreased with distance while P wave velocity increased. At about 1 km from the fault plane, the relative variations reached 43%, 65%, and 20% for porosity, permeability, and P wave velocity, respectively. This suggests that tectonic loading changed the petrophysical properties inherited from sedimentation and diagenesis. Using field constraints and assuming overburden-related inelastic compaction in the proximity of the fault plane, we conclude that the fault reached the mechanical condition for rupture in compression at differential stress of 64.8 MPa at a depth of 1500 m

Fault structure and slip localization in carbonate-bearing normal faults: An example from the Northern Apennines of Italy

Carbonate-bearing normal faults are important structures for controlling fluid flow and seismogenesis within the brittle upper crust. Numerous studies have tried to characterize fault zone structure and earthquake slip processes along carbonate-bearing faults. However, due to the different scales of investigation, these studies are not often integrated to provide a comprehensive fault image. Here we present a multi-scale investigation of a normal fault exhumed from seismogenic depths. The fault extends for a length of 10 km with a maximum width of about 1.5 km and consists of 5 sub-parallel and interacting segments. The maximum displacement (370e650 m) of each fault segment is partitioned along sub-parallel slipping zones extending for a total width of about 50 m. Each slipping zone is characterized by slipping surfaces exhibiting different slip plane phenomena. Fault rock development is controlled by the protolith lithology. In massive limestone, moving away from the slip surface, we observe a thin layer (<2 cm) of ultracataclasite, cataclasite (2e10 cm) and fault breccia. In marly limestone, the fault rock consists of a cataclasite with hydrofractures and smectite-rich pressure solution seams. At the micro-nanoscale, the slip surface consists of a continuous and thin (<300 mm) layer composed of coarse calcite grains (~5e20 mm in size) associated with sub-micrometer grains showing fading grain boundaries, voids and/or vesicles, and suggesting thermal decomposition processes. Micrometer-sized calcite crystals show nanoscale polysynthetic twinning affected by the occurrence of subgrain boundaries and polygonalized nanostructures. Investigations at the kilometres-tens of meter scale provide fault images that can be directly compared with high-resolution seismological data and when combined can be used to develop a comprehensive characterization of seismically active fault structures in carbonate lithologies. Micro and nanoscale investigations along the principal slipping zone suggest that different deformation processes, including plastic deformation and thermal decomposition, were active during seismic slip

Validation of ash/dust detections from SEVIRI data using ACTRIS/EARLINET ground-based LIDAR measurements

Twotailored configurations of the Robust Satellite Technique (RST) multi-temporal approach, for airborne volcanic ash and desert dust detection, have been tested in the framework of the European Natural Airborne Disaster Information and Coordination System for Aviation (EUNADICS-AV) project. The two algorithms, running on Spinning Enhanced Visible Infra-Red Imager (SEVIRI) data, were previously assessed over wide areas by comparison with independent satellite-based aerosol products. In this study, we present results of a first validation analysis of the above mentioned satellite-based ash/dust products using independent, ground-based observations coming from the European Aerosol Research Lidar Network (EARLINET). The aim is to assess the capabilities of RST-based ash/dust products in providing useful information even at local scale and to verify their applicability as a "trigger" to timely activate EARLINET measurements during airborne hazards. The intense Saharan dust event of May 18-23 2008-which affected both the Mediterranean Basin and Continental Europe-and the strong explosive eruptions of Eyjafjallajökull (Iceland) volcano of April-May 2010, were analyzed as test cases. Our results show that both RST-based algorithms were capable of providing reliable information about the investigated phenomena at specific sites of interest, successfully detecting airborne ash/dust in different geographic regions using both nighttime and daytime SEVIRI data. However, the validation analysis also demonstrates that ash/dust layers remain undetected by satellite in the presence of overlying meteorological clouds and when they are tenuous (i.e., with an integrated backscatter coefficient less than ~0.001 sr-1 and with aerosol backscatter coefficient less than ~1 × 10-6 m-1sr-1). This preliminary analysis confirms that the continuity of satellite-based observations can be used to timely "trigger" ground-based LIDAR measurements in case of airborne hazard events. Finally, this work confirms that advanced satellite-based detection schemes may provide a relevant contribution to the monitoring of ash/dust phenomena and that the synergistic use of (satellite-based) large scale, continuous and timely records with (ground-based) accurate and quantitative measurements may represent an added value, especially in operational scenarios

Data for: The seismic signature of heavy oil on carbonate reservoir through laboratory experiments and AVA modelling

Samples measurement

The seismic signature of heavy oil on carbonate reservoir through laboratory experiments and AVA modelling

The influence of unconventional oil on the petrophysical properties of carbonate rocks is of primary interest in petroleum science. In this work, we first provided a thorough petrophysical characterization in laboratory by measuring density, porosity, VP and VS of a bitumen carbonate reservoir rock outcropping in the Majella Mountain (Central Italy). The presence of bitumen stiffens the rock and causes an increases of the acoustic impedance (AI) and a strong decrease of the VP/VS ratio respect to brine saturation. On the contrary, lighter oil causes a decrease of the AI and a slight decrease of the VP/VS ratio in comparison with a saturation in brine. Then, we performed a Synthetic Amplitude vs Angles (AVA) modelling showing that through the AVA ana- lysis, it is possible to recognize the type of fluid that saturates the analyzed carbonate reservoir rocks. We also observed that the increasing porosity plays a key role in the AVA response, by decreasing the bulk density and seismic waves velocities and increasing the amount of fluids that saturate the rocks. By applying our laboratory and modelling results to a public stacked seismic line we show that our results may help in recognize heavy oil directly from seismic data

Petrophysical properties variation of bitumen-bearing carbonates at increasing temperatures from laboratory to model

Variations in reservoir seismic properties can be correlated to changes in saturated-fluid properties. Thus, the determination of variation in petrophysical properties of carbonate-bearing rocks is of interest to the oil exploration industry because unconventional oils, such as bitumen (HHC), are emerging as an alternative hydrocarbon reserve. We have investigated the temperature effects on laboratory seismic wave velocities of HHC-bearing carbonate rocks belonging to the Bolognano Formation (Majella Mountain, central Italy), which can be defined as a natural laboratory to study carbonate reservoir properties. We conduct an initial characterization in terms of porosity and density for the carbonate-bearing samples and then density and viscosity measurements for the residual HHC, extracted by HCl dissolution of the hosting rock. Acoustic wave velocities are recorded from ambient temperature to 90°C. Our acoustic velocity data point out an inverse relationship with temperature, and compressional (P) and shear (S) wave velocities show a distinct trend with increasing temperature depending on the amount of HHC content. Indeed, samples with the highest HHC content show a larger gradient of velocity changes in the temperature range of approximately 50°C-60°C, suggesting that the bitumen can be in a fluid state. Conversely, below approximately 50°C, the velocity gradient is lower because, at this temperature, bitumen can change its phase in a solid state. We also propose a theoretical model to predict the P-wave velocity change at different initial porosities for HHC-saturated samples suggesting that the velocity change mainly is related to the absolute volume of HHC

Data for: The seismic signature of heavy oil on carbonate reservoir through laboratory experiments and AVA modelling

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