ALBERT

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

Description: Geological storage is one of the most promising technologies for reducing anthropogenic atmospheric emissions of CO2. Among the several CO2 storage techniques, sequestration in deep-seated saline aquifers implies four processes: a) supercritical fluid into geologic structure (physical trapping), b) dissolved CO2(aq) due to very long flow path (hydrodynamic trapping), c) dissolved CO2(aq) (solubility trapping), and d) secondary carbonates (mineral trapping). The appealing concept that CO2 can permanently be retained underground has prompted several experimental studies in Europe and North America sponsored by IEA GHG R&D, EU and numerous international industrials and governments, the most important project being the International Energy Agency Weyburn CO2 Monitoring & Storage, an EnCana’s CO2 injection EOR project at Weyburn (Saskatchewan, Canada). Owing to the possible risks associated to this technique, numerical modelling procedures of geochemical processes are necessary to investigate the short- to long-term consequences of CO2 storage. Assumptions and gap-acceptance are made to reconstruct the reservoir conditions (pressure, pH, chemistry, and mineral assemblage), although most strategic geochemical parameters of deep fluids are computed by a posteriori procedure due to the sampling collection at the wellhead, i.e. using depressurised aliquots. In this work a new approach to geochemical model capable of to reconstruct the reservoir chemical composition (T, P, boundary conditions and pH) is proposed using surface analytical data to simulate the short-medium term reservoir evolution during and after the CO2 injection. The PRHEEQC (V2.11) Software Package via thermodynamic corrections to the code default database has been used to obtain a more realistic modelling. The main modifications brought about the Software Package are: i) addition of new solid phases, ii) use of P〉0.1 Mpa, iii) variation of the CO2 supercritical fugacity and solubility under reservoir conditions, iv) addition of kinetic rate equations of several minerals and v) calculation of reaction surface area. The Weyburn Project was selected as case study to test our model. The Weyburn oil-pull is recovered from the Midale Beds (1300-1500 m deep) that consist of two units of Mississippian shallow marine carbonate-evaporites: i) the dolomitic “Marly” and ii) the underlying calcitic “Vuggy”, sealed by an anhydrite cap-rock. About 3 billions mc of supercritical CO2 have been injected into the “Phase A1” injection area. The INGV and the University of Calgary (Canada), have carried out a geochemical monitoring program (ca. thrice yearly- from pre-injection trip: “Baseline” trip, August 2000, to September 2004). The merged experimental data are the base of the present geochemical modeling. On the basis of the available data, i.e. a) bulk mineralogy of the Marly and Vuggy reservoirs; b) mean gas-cap composition at the wellheads and c) selected pre- and post-CO2 injection water samples, the in-situ (62 °C and 0.1 MPa) reservoir chemical composition (including pH and the boundary conditions as PCO2, PH2S) has been re-built by the chemical equilibrium among the various phases, minimizing the effects of the past 30-years of water flooding in the oil field. The kinetic evolution of the CO2-rich Weyburn brines interacting with the host-rock minerals performed over 100 years after injection have also been computed. The reaction path modeling suggests that CO2 can mainly be neutralized by solubility and mineral trapping via Dawsonite precipitation. To validate our model the geochemical impact of three years of CO2 injection (September 2000-2003) has been simulated by kinetically controlled reactions. The calculated chemical composition after the CO2 injection is consistent with the analytical data of samples collected in 2003 with a 〈5 % error for most analytical species, with the exception of Ca and Mg (error 〉90%), likely due to the complexation effect of carboxilic acid.

Description: Published

Description: Rimini, Italy

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: On the Forecasting Horizon of Seismicity Models

Description: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy Institute of Statistical Mathematics (ISM), Tokyo, Japan Swiss Seismological Service, Institute of Geophysics (ETH), Zürich, Switzerland

Description: Unpublished

Description: Erice, Italy

Description: open

Description: Recent strong (M 6.6) earthquakes in Greece are examined from the point of view of two current, but disparate, approaches to long-term seismogenesis. These are the evolving stress field (ESF) approach, in which earthquakes are considered to be triggered by accumulated stress changes from past earthquakes and tectonic loading on the major faults, and the precursory scale increase (Y) approach, in which a major earthquake is preceded in the long term by an increase in minor earthquake occurrences, with the magnitude of the precursory earthquakes, and the precursor time and area all scaling with the major earthquake magnitude. The strong earthquakes are found to be consistent with both approaches, and it is inferred that both approaches have a relevant role to play in the description of the long-term generation process of major earthquakes. A three-stage faulting model proposed previously to explain the Y phenomenon involves a major crack, which eventually fractures in the major earthquake, being formed before the onset of precursory seismicity. Hence we examine whether ESF can account for the formation of the major crack by examining the accumulated stress changes at the time of the onset of Y for each strong earthquake. In each case, the answer is in the affirmative; there is enhanced stress in the vicinity of the main shock at the time of the onset. The same is true for most, but not all, of the locations of precursory earthquakes.

Description: Published

Description: B05318

Description: reserved

Description: In January 2002, Nyiragongo volcano erupted 14–34 × 106 m3 of lava from fractures on its southern flanks. The nearby city of Goma was inundated by two lava flows, which caused substantial socioeconomic disruption and forced the mass exodus of the population, leaving nearly 120,000 people homeless. Field observations showed marked differences between the lava erupted from the northern portion of the fracture system and that later erupted from the southern part. These observations are confirmed by new 238U and 232Th series radioactive disequilibria data, which show the presence of three different phases during the eruption. The lavas first erupted (T1) were probably supplied by a residual magma batch from the lava lake activity during 1994–1995. These lavas were followed by a fresh batch erupted from fissure vents as well as later (May–June 2002) from the central crater (T2). Both lava batches reached the surface via the volcano's central plumbing system, even though a separate flank reservoir may also have been involved in addition to the main reservoir. The final phase (T3) is related to an independent magmatic reservoir located much closer (or even beneath) the city of Goma. Data from the January 2002 eruption, and for similar activity in January 1977, suggest that the eruptive style of the volcano is likely to change in the future, trending toward more common occurrence of flank eruptions. If so, this would pose a significant escalation of volcanic hazards facing Goma and environs, thus requiring the implementation of different volcano-monitoring strategies to better anticipate where and when future eruptions might take place.

Description: Published

Description: B09202

Description: 3.6. Fisica del vulcanismo

Description: JCR Journal

Description: reserved

Description: Time-invariant, long-range, and short-range forecasting models were fitted to the earthquake catalogue of Greece for magnitudes 4.0 and greater to optimize their ability to forecast events of magnitude 6.0 and greater in the period 1966–1980. The models considered were stationary spatially uniform and spatially varying Poisson models, a long-range forecasting model based on the precursory scale increase phenomenon with every earthquake regarded as a precursor according to scale, and epidemic type short-range forecasting models with spatially uniform and spatially varying spontaneous seismicity. Each of the models was then applied to the catalogue for 1981–2002, and their forecasting performance was compared using the log likelihood statistic. The long-range forecasting model performed substantially better than the time-invariant models, and the short-range forecasting models performed substantially better again. The results show that the information value to be gained from modeling temporal and spatial variation of earthquake occurrence rate, at both long and short range, is much greater than can be gained from modeling spatial variation alone.

Description: Published

Description: B09304

Description: JCR Journal

Description: reserved

Description: In this work we present a new approach to model the effects of CO2 sequestration that has been tested in the Weyburn test site. The Weyburn oil-pull is recovered from Midale Beds (at 1300-1500 m depth). This formation consists of Mississippian shallow marine evaporitic carbonates that can be divided into two units: i) the dolomitic “Marly” and ii) the underlying calcitic “Vuggy”, sealed by an anhydrite cap-rock. Presently, about 3 billions mc of supercritical CO2 have been injected into the “Phase A1” injection area. The aim of our model is to reconstruct i) the chemical composition of the reservoir; ii) the geochemical evolution of the reservoir with time as CO2 is injected and ii) the boundary conditions. The geochemical modeling has been performed by using the code PRHEEQC (V2.11) software package. The “primitive brine” composition was calculated on the basis of the chemical equilibrium among the various phases, assuming reservoir equilibrium conditions for the mineral assemblage with respect to a Na-Cl (Cl/Na=1.2) water, at T of 62 °C and P of 150 bars via thermodynamic corrections to the code database. A comparison between the chemical composition of the “primitive brine” and that analytically determined on water samples collected before the CO2 injection shows an agreement within 10 %. Furthermore, we computed the kinetic evolution of the reservoir by considering the local equilibrium and the kinetically controlled reactions taking into account the CO2 injected during four years of monitoring. The calculated chemical composition after the CO2 injection is consistent with the analytical data of samples collected in 2004, with the exception of calcium and magnesium contents. The results of the Inverse Modeling Simulation (IMS) suggest that the measured Ca and Mg contents are higher than those calculated from the solubility of calcite and dolomite, likely due to the complexation effect of carboxilic acid. The results of the application of the kinetic model lasting 100 years indicate that dissolution of K-feldspar and kaolinite and precipitation of chalcedony affect the Marly and Vuggy units. Furthermore, calcite tends to be dissolved as CO2 solubilises in the reservoir, whereas dolomite dissolution can be considered negligible. Dawsonite precipitates as secondary mineral. The CO2 content from solubility trapping (short/medium-term sequestration) calculation is ~0.8 mol/L.

Description: Published

Description: Pechino, Cina

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: Article

Description: On 17 January 2002, the Nyiragongo volcano (1.52°S, 29.25°E, 3469 meters above sea level), located about 18 kilometers north of Lake Kivu in the Democratic Republic of Congo, erupted, releasing a volume of 14-34 million cubic meters of lava. Lava flows originated from north-south oriented fractures that rapidly developed along the southern flank of the volcano. Two lava flows divided the nearby city of Goma (~500,000 people) into two parts, forcing a rapid exodus of the population into Rwanda. One of these lava flows ran into Lake Kivu, encroaching 60 meters below lake level with a submerged lava volume of 1 million cubic meters. About 15% of the town was directly affected, leaving approximately 120,000 people homeless. At least 170 people died as a direct consequence of the eruption

Description: American Geophysical Union

Description: Published

Description: 177-188

Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani

Description: N/A or not JCR

Description: reserved

Description: Integration of geological and macroseismic data to define probable seismic scenarios in terms of macroseismic intensity and related seismogenic source models. The Maiella 1706 earthquake (Abruzzo, Italy)

Description: Published

Description: Roma, Italy

Description: 3.10. Sismologia storica e archeosismologia

Description: open

Description: The New Zealand Earthquake Forecast Testing Centre

Description: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy Institute of Statistical Mathematics (ISM), Tokyo, Japan Swiss Seismological Service, Institute of Geophysics (ETH), Zürich, Switzerland

Description: Unpublished

Description: Erice, Italy

Description: open