ALBERT

Description: Seven 222Rn soil gas surveys have been accomplished throughout the N-E area of Stromboli Island. The former survey has been performed in July 2001, in a quiescent period since 1985, throughout a grid of 50 sites. The same grid has been repeated, in January 2003, soon after December, 28, 2002 eruption onset. The other surveys have been carried out in March 2003, in June 2003 after the April, 5, 2003 paroxysm event, and in July 2004 and March 2005 (quiescent periods). Finally, CO2 fluxes and soil gas surveys (Rn, CO2, CH4, H2, O2, N2, He) have been performed in March 2007 after the slightly February 2007 eruption onset. Results have highlighted correlated and synchronous 222Rn soil gas changes throughout the grid, allowing to discriminate the sectors of maximum increased 222Rn emission at surface, with a volcano-tectonical significance, mostly in January and March 2003 surveys. The positive NE-SW anomalies have been found maximum up to 13.000 Bq/m3 in January 2003, while after the Rn values returned to pre-eruptive values. Plotting single point concentration versus monitoring time, it is well evident that, in proximity of a paroxysm event, always the same points undergo to a radon concentration increasing. Data set of the investigated area has been divided in eight zones (on the basis of geographic sectors of the island). In every zone maximum Rn values correspond to the paroxysmal phase of the Stromboli eruptions. In particular, highest radon values are found in the “Lampara – COA” and “Town Hall” zones located along the known N40° lineament. After the eruptive phase, concentrations start to decrease. The NW-SE extension could be linked to the ongoing volcano collapse toward the NW located Sciara del Fuoco slope. Also the SE sector could undergo to collapses, along weakness lines (faults and fractures) whose prolongation in the Mole-S14 zone could release anomalous CO2-fluxes and anomalous soil gas concentrations (up to 10-20 % in CO2) dangerous for human health. The importance of geochemical monitoring together with volcanic time series, is a valid tool for evaluating the volcanic hazard.

Description: Unpublished

Description: Reykjavík - ICELAND

Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive

Description: open

Description: Italy is one of the most promising prone areas to study the CO2 behavior underground, the caprock integrity to the CO2 leakage, mostly in presence of pervious/geochemically active faults, due to a wide availability of CO2 rich reservoirs at a depth between 1 and 10 km, as highlighted by recent literature. These deep CO2 reservoirs generate at least 200 leakage areas at surface throughout Italy which have been defined “Diffuse Degassing Structures” (DDS) by INGV. These are widely studied by INGV institutionally by a long term convention with the Civil Protection Department (DPC) with the aim to catalog, monitor and assess the Natural Gas Hazard (NGH, namely the probability of an area to become a site of poisonous peri – volcanic gas exhalation from soils). More than 150 researcher of INGV are involved in monitoring areas affected by the CO2 presence underground and at surface, by continuous monitoring on-line networks (around 40 stations throughout Italy, including the Etna area, Aeolian Islands, Umbria region, Piemonte region, etc…) and discretely (9 groups of research were involved in the last years to localize, define and monitor almost all the DDSs in Italy), by sampling and analyzing chemical and isotopic compounds, useful to discriminate the origin, evolution and natural gas hazards of the examined DDS. In this paper, we will discuss some DDS catalogued and studied by a Rome INGV Research Unit (UR 11) which focused its work in Central Italy, throughout different DDS, also in relation to the diverse seismotectonic settings, to discover buried faults as possible gas leakage pathways, mostly if they are “geochemically” activated. In particular we discuss, among the discrete monitoring techniques exploited by INGV, soil gas surveying, which consists in a collection of gas samples from the soil zone not saturated (dry zone) to measure the geogas gaseous species both in fluxes (CO2, CH4, 222Rn) and in concentration (He, H2, H2S, helium, hydrogen, CO2, CH4, 222Rn), that permeate the soil pores. The total CO2 flux budget was calculated as “baseline” degassing rate of these “CO2 analogues”. A good discrete areal monitoring is prerequisite to design sound continuous monitoring network to monitor CO2 related parameters in liquid/gas phases, to review the protocol of the Annex II of the European Directivity on CCS.

Description: Published

Description: 2135-2142

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: N/A or not JCR

Description: reserved

Description: Soon after a 222Rn and 220Rn survey in soil gases, performed (June 2005) in the frame of the Diffuse Degassing in Italy risk assessment project, a moderate earthquake (Mw=4.6) occurred in the Anzio offshore, on August, 22, 2005, only 5 miles from the Tor Caldara Diffuse Degassing Structure (DDS onward). Having available the pre-earthquake 222Rn and 220Rn grid-map on around 50 soil-gas points and being 222Rn both a stress-pathfinder and a discriminative component of activated-faults, a mirrorlike survey was repeated on the same 50 sites, soon after the close earthquake. Later, during a quiescent-aseismic period (December, 2005), a CO2 flux survey was performed for the same 50 sites, adding detailed measurements (more than 100 sites) for the highest flux sectors. The aim of this survey was both to have an overall picture of the background CO2 flux and to calculate the total budget of CO2 flux throughout the DDS, to better interpret the 222Rn and 220Rn areal surveys before and after the seismic event. Herewith, we distinguish the contribution of organic, diffusive and advective CO2 flux. Hints of convection and strong degassing linked to the fracture field, inside the DDS, have been envisaged on selected points, where continuous monitoring stations could be strategic, for seismic, volcanic and NGH surveillance. Despite we found higher 222Rn values in soils after the earthquake, suggesting an enhanced local degassing probably linked to a stress signal throughout the DDS as a whole, the results highlight an unmodified shape and location of the 222Rn anomalies before and after the earthquake. This evidence excludes both that the activated seismogenic segment has affected in some ways both the DDS degassing patterns and that fracture field changed. A similar result could be expected if the activated fault was oriented along the DDS itself and reached the surface. This evidence is well correlated with the reconstructed focal mechanism of the earthquake, pertaining to the transfer structure of the Ardea Graben , located along a peripheral sector of the degassing Alban Hills volcano and intersecting the DDS Tor Caldara itself. The shape and location of 222Rn anomalies inside the DDS for both the surveys are strictly inversely correlated with the areal CO2 flux data. The geometry of the degassing pathways is probably linked to the barrier action (sealing power) of the clays cropping out in the study area. These clays are generated by the strong leaching of the outcropping sedimentary Pleistocene rocks due to the huge flux of volcanic gas -rich fluids.

Description: Published

Description: Perugia, Italy

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: Natural gas emissions represent extremely attractive surrogates for the study of CO2 effects both on the environment and human life. Three Italian case histories demonstrate the possible co-existence of CO2 natural emissions and people since roman time. The Solfatara crater (Phlegraean fields caldera, Southern Italy) is an ancient roman spa. The area is characterized by intense and diffusive fumarolic and hydrothermal activity. Soil gas flux measurements show that the whole area discharges between 1200 and 1500 tons of CO2 a day. In proximity of Panarea island (Aeolian islands, Southern Italy), on November, 2002 a huge submarine volcanic-hydrothermal gas burst was advised. The submarine gas emissions locally modified seawater pH (from 8.0 to 5.0) and Eh (from +80 mV to -200 mV), causing strong modification in the marine ecosystem. Collected data suggest an intriguing correlation between the gas/water vent location/evolution and the main local and regional fault. CO2 degassing characterizes also the Telese area (Southern Italy), one of the most seismically active segments of the Southern Apennine belt with the occurrence of five large destructive earthquakes in the last 500 years. Geochemical surveys in this area, reveal the presence of high CO2 content in ground-water. Carbon isotopic analysis of CO2 revealed its deep origin probably caused by the presence of a cooling magmatic intrusion inside the carbonatic basement. All the above mentioned areas are constantly monitored since they are densely populated. Although natural phenomena are not always predictable, nevertheless local people learnt to manage and, in some case, to exploit these phenomena, suggesting a big human adaptability also in extreme situations.

Description: Published

Description: 175-190

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: reserved

Description: EnCana’s CO2 injection EOR project at Weyburn Saskatchewan (Canada) is the focal point of a multi-faceted research program, sponsored by the IEA GHG R&D and numerous international industrial and government partners. More than yearly strontium isotope, trace element and dissolved gas surveys were conducted by INGV in conjunction with the thrice yearly borehole fluid sampling trips performed by the Canadian partners. This paper focuses on the Sr isotope monitoring. Approximately 25 samples were collected over three years for 87Sr/86Sr analyses. At Weyburn, a water-alternating-gas (WAG) EOR technique is used to inject water and CO2 into the Mississippian Midale reservoir. 87Sr/86Sr ratios for produced fluids fall between 0.7077 and 0.7082, consistent with published values for Mississippian fluids and carbonate minerals. A small 87Sr/86Sr component of this produced fluid is derived from waters of the Cretaceous Mannville aquifer, which has been used for water-flooding EOR since 1959. The progressively more positive Sr isotope trend from 2001 to 2003 may be due to: 1) a smaller Mannville aquifer component in the water flooding process; and/or 2) the dissolution of Mississippian host rocks during the ongoing CO2 injection. Evidence that 87Sr/86Sr values are approaching those of Mississippian host-rock values may point towards zones of carbonate dissolution as a result of continuing CO2 injection. This hypothesis is strengthened by i) 13C data; ii) preliminary “gross composition” of dissolved gases (H2S, CO2, CH4, He, H2) and iii) by trace elements data

Description: Published

Description: 243-259

Description: 4.4. Scenari e mitigazione del rischio ambientale

Description: reserved

Description: The 2009 L’Aquila seismic sequence, whose main shock (Ml 5.8, Mw 6.3) occurred on April 6th at 1:32 UTC, is still ongoing (August 2009) along the central Apenninic Belt (Abruzzo region, central Italy). The main earthquake was destructive and caused 300 casualties; its epicenter has been located at 42.35°N, 13.38°E, at a depth of around 10 km. The main shock was preceded by a long seismic sequence, started several months before (i.e., December 2008, with a total of 300 earthquakes with Mlmax = 4.0). After the April 6th main event, two other earthquakes struck the area on April 7th and 9th, with Ml 5.3 and 5.1, respectively. A lot of evidences stress the role of the pore-pressure evolution of deep fluids in generating the L’Aquila sequence (e.g. Vp/Vs anomalous ratio, Chiarabba C., 2009 personal communication) as occurred for the Umbria Marche (central Italy) 1997-1998 seismic sequence (Quattrocchi, 1999 and references herein). The entire sequence highlights more than one seismogenic segment activated along a main NW-SE-trending Apenninic lineament (Fig. 1). Soon after the strongest event, our group (UF “Fluid Geochemistry, Geological Storage and Geothermics”, Department Rome 1, INGV) carried out a geochemical study throughout the seismically activated area by sampling around 600 soil gas points and around 70 groundwater points (springs and wells). The main goal of this study was the comprehension of both the behaviour and the geometry of the activated fault segments by means the application of specific geochemical methods, already exploited in other Italian seismic and volcanic areas (Quattrocchi et al., 2000; Pizzino et al., 2004; Quattrocchi et al., 2008; Voltattorni et al., 2009).In particular, here we discuss only the results gathered by measuring soil gases, considering fluxes of CO2 and CH4 as well as concentrations of radon, CO2, CH4, He, H2, N2, H2S, O2, and other minor geogas (i.e. light hydrocarbons) in the main sectors of the activated seismic sequence (see the red box in figure 1). The geochemical measurements were addressed to more than one objective. One was to update a GIS of the co-seismic effects (associated to the earthquakes with magnitude greater than ML=5.0 and surveyed by our INGV EmerGeo Working Group) and their spatial and geometrical parameters in the local geological framework. More than 400 observation sites (fractures mainly) have been detected in an area of ~ 900 km2, part of which coupled with geochemical measurements in soils (fluxes and concentrations). Most of the surface effects have been observed also as regards the presence/absence at surface of deep fluids uprising (hot water, gas pools/fluxes, vapours, etc….) along and close to the previously mapped active faults (INGV Catalogue of Strong Historical earthquakes). Geochemical measurements in soils are very powerful to discriminate the numerous local surface effects (landslides, differential compaction, rock falling, etc) with respect to the real signatures of the expression at surface of the activated seismogenic segment. For earthquakes of moderate magnitude, such as the L’Aquila 2009 event, where the superficial effects could be absent or not evident, our geochemical method demonstrated to be strategic and potentially applicable in other worldwide seismic areas. Most ruptures with a structural significance have been observed along the Paganica Fault (elongated NW-SE); also the Bazzano and Monticchio-Fossa faults have been geochemically analysed; we searched the different behaviour of these structures as a whole, each having a different tectonic role (passive, active, transfer, crossing point, etc.), in determining the degassing observed at surface. The results highlight the maximum geochemical anomalies just along a minor anti-apenninic NE-SW transverse lineament; here, CO2 (up to 2000 [gm-2day-1]) and CH4 (up to 300 [gm-2day-1] anomalous fluxes were found soon after the main shock, remaining anomalous in the following months, but with lower values. Furthermore, just in correspondence of this lineament highest values of radon (up to 40.000 Bq/m3) were found. The transects perpendicular to the Paganica Fault clearly highlighted the role of the main fracture at surface (masked in few days) as preferential pathway for gases escaping from depth, as revealed by geochemical methods. The measured values are in any case not dangerous for the people’s health and minimise the problem of CO2-CH4 burst or explosions during strong earthquakes when these gases are stored naturally underground (km), as under these activated faults (as showed by the deep wells drilled in the area). Finally, the soundest sites to install 3 continuous monitoring stations, measuring the CO2 fluxes, were selected and the stations installed (Paganica, Bazzano and S. Gregorio sites) in cooperation with colleagues coming from the INGV geochemical department of Palermo (Sicily, southern Italy). The considered geochemical methods could be exploited along other faults in Italy and abroad by performing pre-main shock geochemical surveys to i) highlight earthquake preparation discovering anomalous degassing; ii) draw a picture of fault degassing before strong seismic events and, later, during a seismic sequence; iii) to highlight transverse lineaments among main fault segments, adding information where geo-structural expressions at surface are hidden.

Description: Published

Description: Damascus-Syria

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: Pantelleria is an active volcanic complex, at present in quiescent status, hosting a high enthalpy geothermal system. Explorative geothermal wells tapped exploitable water-dominated reservoirs at 600-800 m depth with maximum measured temperatures of 250°C. Five field campaigns for soil gas measurements were made in the period from July 2005 to October 2006. CO2 flux was measured with the accumulation chamber method at 807 sites, CO2 concentration and Rn activity in soil atmosphere were measured at 50 cm depth at 728 and 358 sites, respectively. The first campaign covered the whole island (about 83 km2) with an approximately sample density of 3.5 points per km2 for CO2 (flux and concentration) measurements and of 1.6 points per km2 for Rn measurements. The distribution of the sampling points was as far as possible evenly distributed. Only few limited areas resulted uncovered due to accessibility problems (inhabited areas, airport, steep or rough topography). In the following four surveys nine areas were studied with greater detail with sample densities of up to 100 points per km2. Flux measurements for the whole surveys gave values in the range 〈 0.1 - 4700 gCO2 m-2 day-1 (Fig. 1). Organic contribution could not be distinguished with statistical methods and in the present study was considered negligible above 30 g m-2 day-1. The sites displaying flux values above this threshold, representing about 32% of the total population, are almost all located within the 50 ka old caldera. The highest values correspond to the areas of Favara Grande and of the lake Specchio di Venere (Fig. 1), which have long been recognized as sites of anomalous degassing with the presence of active fumarolic vents with temperatures of about 100 °C in the former and thermal springs with abundant bubbling gases and a mofette in the latter. A new anomalous degassing area with very high output values has been identified on the southern flank of Mt. Grande (MGS in Fig. 1). In this area the vegetation cover strongly contrasts with that of the neighboring areas, consisting of scrubby low growing plants, mosses and bare land. Indeed, high CO2 flux values are always measured as long as such vegetation cover is found, abruptly decreasing when higher growing plants are present. The contrast is particularly evident in springtime and can be used as a good marker to individuate anomalous degassing areas. Further areas were studied in detail being sites of fumarolic manifestations. All of them are also sites of anomalous CO2 fluxes although of limited areal extension. The area of the last subaerial volcanic activity (Mursia) was also studied but the measurements were all far below the anomaly threshold. The total CO2 output of the anomalous degassing areas was estimated through geostatistical methods considering only values above the anomaly threshold. Results evidence that most of the output (87%) of the island is due to 3 of the anomalous degassing areas (Lake, MGS and Favare), the first of which accounts for more than 50%. Summing up the contribution of all anomalous areas we obtained a total output of about 0.3 kg s-1 (26 t day-1) over an area of about 0.58 km2. Concentrations of CO2 ranged from 0.039 (atmospheric value) up to 95 % (Fig. 1). The distribution of the values on a probability plot evidenced two statistically distinct populations with an inflection point at about 0.8 %. The values below the threshold (65 % of the population) can be considered as derived from organic activity while those above of magmatic/geothermal origin. The spatial distribution of the sites with anomalous concentrations closely resembles those of anomalous CO2 fluxes. Radon222 activity in the soil ranged from 〈 0.1 to 〉1000 kBq m-3 (Fig. 1). The distribution of the values on a probability plot evidenced three statistically distinct populations with inflection points at 40 and 400 kBq m-3. The lower population (74% of the entire population) probably corresponds to close to equilibrium values in soils with different contents of parent isotopes of the 238U decay chain and could be considered as background population. The values of the other two populations have to be considered anomalous and their high activity values have to be related either to sustained fluxes of a carrier gas (CO2) or/and to enhanced release from the soil due to fumarolic alteration. These anomalous values generally correspond to elevated CO2 flux values and are found close to active or fossil fumarolic areas. The close relationship with fumarolic alteration is confirmed by the contrasting behavior of two of the areas displaying the highest CO2 flux values, namely Favare and Lake. In the former area the high soil temperatures, testifying for anomalous fluxes of hydrothermal fluids, are reflected in a high percentage of anomalous values of soil 222Rn activity. On the contrary at the lake area, where the highest CO2 fluxes are measured, soil temperatures are much lower and consequently also soil 222Rn activity. The only high soil 222Rn activity values are measured along the southern shores of the lake where seeps of thermal water with about 60 °C are present. At Mursia, where recent basaltic lavas and scorias crop out, soil 222Rn activity is particularly low due to the low content of parent radioactive elements in these rocks. Finally, the present study evidenced a few areas were the gas hazard due to both CO2 and radon is elevated with either acute or chronic health issues for humans. These are the western shores of the lake and the village of Rekale the only inhabited area close to an anomalous degassing area.

Description: Published

Description: Patras, Greece

Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi

Description: open

Description: EnCana’s CO2 injection EOR project at Weyburn (Saskatchewan, Canada) is the focal point of a multi-faceted research program, sponsored by IEA GHG R&D and numerous international industrial and government partners including the European Community (BGS, BRGM, INGV and GEUS research providers), to find co-optimization of “CO2-EOR Production” and “CO2 -Geological Storage”, addressed to environmental purposes, in the frame of the Kyoto Agreement Policies. The Weyburn oil-pull is recovered from Midale Beds (at the depth of 1300-1500 m). This formation consists of Mississipian shallow marine carbonate-evaporites that can be subdivided into two units: i) the dolomitic “Marly” and ii) the underlying calcitic “Vuggy”, sealed by an anhydrite cap. Presently, around 3 billions mc of supercritical CO2 have been injected into the “Phase A1”injection area that includes around 90 oil producers, 30 water injectors and 30 CO2 injection wells, build up since September 2000. INGV has carried out a geochemical monitoring programme -approximately thrice yearly from pre-injection (“Baseline” trip, August 2000) to September 2004- performing trace element and dissolved gas analysis along with fluids sampling surveys, the latter being performed by the Canadian partners. The experimental data are the base of a geochemical modelling, i.e. the main goal of the present study. In the past, assumptions and gap-acceptance have been made in the literature in the frame of the geochemical modelling of CO2 geological storage, in order to reconstruct the reservoir conditions (pressure, pH and boundary conditions). As these parameters of deep fluids cannot be measured in-situ, all this information must be computed by a a posteriori procedure involving the analytical data. In this work we proposed an approach to geochemical modeling in order to:: i) reconstruct the in-situ reservoir chemical composition (including pH) and ii) evaluate the boundary conditions (e.g. pCO2, pH2S), necessary to implement the reaction path modelling. This is the starting point to assess the geochemical impact of CO2 into the oil reservoir and, as main target, to quantify water-gas-rock reactions. Our geochemical modelling procedure is based on the available data such as: a) bulk mineralogy of the Marly and Vuggy zones; b) average gas-cap composition and c) pre-and post-CO2 injection selected water samples from Midale Beds. The PRHEEQC (V2.11) Software Package was used to reconstruct the in-situ reservoir composition by calculating the chemical equilibrium among the various phases at reservoir temperature (60°C) and pressure (150 bars) conditions by suitable thermodynamic corrections to code database. Then, we identified possible compositions of the initially reservoir liquid phases, always taking into account the case histories of the Marly and Vuggy units. The inverse modelling simulation (IMS) was then performed in order to calculate the amounts of mass transfer of liquid, gas and solid phases that accounted for changes in the water chemistry between the 2000 and 2003 data-sets. IMS calculations suggest that the reservoir underwent mineralogical changes, such as precipitation of chalcedony, gypsum and kaolinite and dissolution of anhydrite and k-feldspar. Calcite dissolution is predicted, but the precipitation of others carbonates (dolomite, dawsonite and siderite) can also occur. Finally, we modelled the geochemical impact of CO2 injection on Weyburn reservoir subjected to both local equilibrium and kinetically controlled reactions. All experimental data and thermo-kinetic modeling of the evolution of the CO2-rich Weyburn brine interacting with host rock minerals performed over 100 years after injection confirm that “solubility trapping” is prevailing in this early stage of CO2 injection. Further and detailed studies on the evolution of the CO2-rich Weyburn brine is one of main aims of this study in the framework of a PhD programme between the INGV of Rome and the Department of Earth Sciences of Florence.

Description: Published

Description: Berkeley, California

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open