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Rome, Italy

Balletto E.,University of Turin | Bonelli S.,University of Turin | Borghesio L.,University of Illinois at Chicago | Casale A.,University of Sassari | And 2 more authors.
Italian Journal of Zoology | Year: 2010

This is a methodological paper aimed at comparing methods to assess regional biodiversity. In more detail we compared the effectiveness of hotspots of species richness, of rarity and complementarity in evaluating local animal diversity. Species distributions were sampled over a 10×10 km UTM grid across the Italian territory. We considered 471 species of zygaenids, butterflies, carabines, amphibians and reptiles. Hotspots were analysed at national and regional levels and considered taxa either all together, or separately. To test the predictive value of complementarity analysis, we initially excluded zygaenids. At national level, of 3218 10×10 km UTM quadrats sampled, 161 (5% of total) had highest species richness. Islands included only 1 hotspot (Sicily). Sixty-eight species (14.4%) were not represented. They were mainly endemic (65%), insular (73.5%), or rare (25%). Working taxon by taxon, hotspots numbered 433. Only 85 (19.6%) were hotspots contemporaneously for two taxa and only 9 were hotspots for 3 taxa. Missing species were fundamentally insular species. The regional-level approach generated 467 hotspots. Eleven species were not represented (2.3%). They had marginal distributions, or were insular endemites. Hotspots of rarity numbered 235 and 10 species were not included. Results demonstrated that hotspots are poor predictors of overall biodiversity. The complementarity method identified 67 quadrats. By definition, these quadrats accounted for all species investigated. They failed, however, to predict the occurrence of three zygaenids. As expected, complementarity provided better results than hotspots analysis. Combining the two methods assures that areas having the highest biodiversity are identified, even working with incomplete databases. Regional or rarity hotspots should generally be preferred to hotspots of species richness. © 2010 Unione Zoologica Italiana. Source

Loizzo M.,Rome University | Bois A.-P.,Universite de Sherbrooke | Etcheverry P.,National Graduate Engineering School | Lunn M.G.,University of Alberta
SPE Economics and Management | Year: 2015

The Paris basin (France) is a particularly challenging setting for oil production: Besides lying under a metropolis of 12-million people, it is also exploited for low-temperature geothermal energy and is crossed by a deep, high-quality drinking-water aquifer of strategic importance, the Albian-Neocomian. Vermilion, the biggest producer in the area, undertook in 2012 a basinwide well-integrity risk-management project with the goal of understanding and minimizing the risk of freshwater-aquifer pollution. The Paris basin operations include 20 fields, for a total of 289 active wells, more than half of which were drilled in the 1980s. The objectives of the leakage risk assessment are twofold: First, identify high-risk scenarios and "must act" wells that require immediate intervention; second, adopt lean (i.e., eliminating waste) prevention and mitigation measures that satisfy the local regulator. The risk-assessment methodology is based on scenarios (i.e., ways in which the hazards, brines or hydrocarbons, can cause damage to targets, the freshwater aquifers). Each scenario involves the failure of a number of barriers with the function to prevent or mitigate damage. In this approach, evidence from in-depth failure analysis is used to build and calibrate scenarios, as well as to validate degradation mechanisms and understand their dynamics. Evidence considered is not limited to drilling reports and wireline logs, but includes all observations, measurements, and weak signals that one can use to test assumptions on the presence, absence, or aging of well integrity. Evidence-based scenarios are complemented by known failure mechanisms, thus reducing the risk of "black swans," very improbable but catastrophic events, even though their probability is constrained by observed behavior during the 4,000 well years of operations in the basin. The criticality (product of probability and severity) of each applicable scenario is then computed by use of an exhaustive database of the characteristics of each well, resulting in a complete risk profile for the basin. The risk-assessment process revealed that casing corrosion caused by brine injection is the biggest driver of well-integrity risk; it also allowed tailoring effective prevention and mitigation actions: For instance, the criticality of scenarios is reduced to an acceptable level if the time between tubing failure and injection stop is kept to 3 months or less. Furthermore, the analysis helps define the role of periodic logging and thus reduce possible waste (i.e., actions that do not contribute to understanding, preventing, or mitigating risk). The evidence-based approach, since applied to another French basin, has proved effective for managing risk at the basin level, by cutting a middle way between universal checklists and the excessively narrow focus of well-by-well analysis: The former are too large and hazy and may hide real dangers among hardly applicable generalities, whereas the latter tends to be expensive and unsystematic and misses recurring patterns. Heavy-duty analytics and modeling are used most efficiently on focused and specific failure analyses to understand the dominant phenomena, which one can then use to paint a quantitative and consistent picture at the level of a field or basin. Copyright © 2015 Society of Petroleum Engineers. Source

Curcio A.,Rome University | Curcio A.,National Institute of Nuclear Physics, Italy | Giulietti D.,National Institute of Nuclear Physics, Italy | Dattoli G.,ENEA | Ferrario M.,National Institute of Nuclear Physics, Italy
Journal of Plasma Physics | Year: 2015

The betatron radiation in the bubble regime is studied in the presence of resonant interaction between the accelerated electrons and the driver laser pulse tail. The calculations refer to experimental parameters available at the FLAME laser facility at the National Laboratories of Frascati (LNF), and represent the radiation spectra and spatial distributions to be expected in forthcoming experiments. © 2015 Cambridge University Press. Source

Frau G.,Rome University | Frau G.,DeepBlue Srl | de Crescenzio F.,University of Bologna | Taurino D.,DeepBlue Srl
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

The present work describes the interactive prototype and the preliminary evaluation results of a tool dedicated to the light General Aviation pilot’s community. The tool’s interface has been developed through an Android tablet application and aims at supporting the pilots in the task of staying “well-clear” from the surrounding traffic by presenting them the long-term prediction of the flights. The initial results and the approach of a heuristic evaluation conducted with five experts coming from the fields of user-experience, aviation and automotive are discussed along with the improvements in the design of the user-interface focusing on the trajectory depictions. © Springer International Publishing Switzerland 2015. Source

Loizzo M.,Rome University | Lecampion B.,University Pierre and Marie Curie | Berard T.,CNRS Paris Institute of Global Physics | Harichandran A.,Imperial College London | Jammes L.,University Paris - Sud
SPE Projects, Facilities and Construction | Year: 2010

Two main types of reservoirs are considered for geological storage of carbon dioxide (CO2): deep saline formations and depleted oil and gas (O&G) reservoirs. The former offers very large potential capacity and a more-even distribution at the expense of high uncertainty because of the very poor characterization of their properties to date, including their sealing capacity. The latter offers smaller overall capacity, but with a reduced risk because of better reservoir knowledge. Gas reservoirs have also provided a proven seal to pressurized gas. However, reusing depleted O&G reservoirs presents challenges that must be considered in the evaluation of performance factors and the associated risks. Depletion can cause pore collapse in the reservoir, with an associated loss of capacity and injectivity and can weaken caprock and bounding faults or even well completions, leading to possible containment losses because of mechanical failure. O&G reservoirs are also intersected by many wells, and it is likely that stricter regulatory requirements on well integrity and the quality of zonal isolation will force operators to recomplete or work over wells that will be exposed to CO 2, with an obvious impact on cost. Low reservoir pressure may also mean that injection of CO2 in a dense phase would result in reservoir fracturing and very strong thermal effects that may lead to injectivity problems. In the reservoir, chemical and physical differences in behavior between CO2 and methane may adversely affect geological containment and injectivity. Analyzing the benefits and challenges with respect to all performance factors (capacity, injectivity, containment) shows that depleted O&G reservoirs and deep saline reservoirs both offer potentially attractive targets for geological storage of CO2, mostly for complementary reasons. Uncertainty on capacity and injectivity is clearly lower for depleted reservoirs, giving them a potential net economic advantage, whereas uncertainty on well containment favors saline formations, which are intersected by fewer wells. Injectivity in depleted reservoirs may be much more difficult to ensure than for saline formations or O&G reservoirs where pressure has been maintained. Saline formations have a lower, mostly unproven, safety margin between injection and fracturing pressure, resulting in a potential advantage for depleted reservoirs where repressurization will lead to a final pressure lower than or equal to the original value. Each reservoir type has a different risk profile, different advantages, and a rightful place in a portfolio of injection sites. © 2010 Society of Petroleum Engineers. Source

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