![]() H2O could have been of exogenous and/or endogenous origin. The chemical species added to the rock during alteration, SO3, V2O3, and SrO, probably originated from a volcanic source. The mass exchange was accompanied by a moderate average decrease in volume of 6.6%. ![]() the difference of elemental gains and losses, shows a net mass loss of about 14.60 g. For one altered rock characterizing theoretically the alteration processes in Gossendorf, mass grains were calculated for SO3, H2O, V and Sr, and mass losses for SiO2, Al2O3, Fe2O3, MnO, Mg0, CaO, Na2O, K2O, P2O5, Cr, Co, Ni, Cu, Zn, Rb, Y, Zr, Nb and Ba with respect to an unaltered latite. The gains depend on the newly formed minerals, the losses, however, on the increase of the porosity in the altered rocks. Drastic differences in gains and losses of certain elements which refer to the different alteration conditions were found to exist not only between different alteration zones but also within such zones. All elements investigated were mobilized during the hydrothermal acid-sulphate alteration process, except Ti, which was selected as the immobile monitor element to calculate mass changes. The associations occur in a zonal arrangement and correspond to the characteristics of the silicic, advanced argillic and argillic alteration terminology. more ABSTRACT The Tertiary latitic rock from Gossendorf, in the Gleichenberg Volcanic Area, Styria, Austria, has in places been completely altered to various associations of the secondary minerals opal-C/-CT, alunite, kaolinite, and montmorillonite. Some of the mineral associations, however, may not be explained by a single alteration process, but must be regarded as the result of multi-stage alteration in which alteration products from weak leaching are super-imposed on alteration products from intense leaching.ĪBSTRACT The Tertiary latitic rock from Gossendorf, in the Gleichenberg Volcanic Area, Styria, Au. The results of experimental alteration tests on the latitic rock in open hydrological systems suggest that these secondary minerals and some of the associations observed in the field as well as their zonal distribution, may have been formed by an originally strongly acid solution rich in SO42- which, undergoing progressive chemical variation by reaction with the rock, exhibits a chemical gradient. These associations occur in a zonal arrangement, in which the innermost part has been totally altered to opal and moreover has retained its original latitic structure. more Summary The latitic rock mined at the Gossendorf open pit in the Gleichenberg Volcanic Area of Styria, Austria, has in places been completely altered to various associations of the secondary minerals opal-C/-CT, alunite, kaolinite and montmorillonite. The gas phase does not flow by advection from the reservoir into the interacting domains so that molecular diffusion in the aqueous phase is the most important process controlling the mass transport occurring in the system under study.Summary The latitic rock mined at the Gossendorf open pit in the Gleichenberg Volcanic Area of St. ![]() Fully water-saturated conditions were assumed for the cement sheath and caprock domains. The effects of the evolving reservoir gas composition are taken into account before, during, and after CO2 injection. On the basis of field data, the system is considered in isothermal (50☌) and isobaric (128.5 bar) conditions. in TOUGH2 User’s Guide, Version 2.0, 1999). in Comput Geosci 32:145–165, 2006) coupled to the TMGAS EOS module (Battistelli and Marcolini in Int J Greenh Gas Control 3:481–493, 2009) developed for the TOUGH2 family of reservoir simulators (Pruess et al. The simulations are performed with the TOUGHREACT simulator (Xu et al. Within a R&D project funded by Eni, we set up a numerical model to investigate the rock–cement alterations driven by the injection of CO2 into a depleted sweet natural gas pool. Such studies are important for injectivity assurance, wellbore integrity, and risk assessment required for CO2 sequestration site qualification. The injection of a reactive gas such as CO2 puts emphasis on the possible alteration of reservoir and caprock formations and especially of the wells’ cement sheaths induced by the modification of chemical equilibria. The injection of CO2 in exploited natural gas reservoirs as a means to reduce greenhouse gas (GHG) emissions is highly attractive as it takes place in well-known geological structures of proven integrity with respect to gas leakage.
0 Comments
Leave a Reply. |