Diagenetische Umwandlungen in Sandsteinen der gasgesättigten, der sekundär verwässerten, der Wasser-, und der Übergangszone des Erdgas – Speichers Haidach in der Molasse Zone, Österreich

Die Sandsteine des untersuchten miozänen Gasspeichers sind resedimentierte Ablagerungen des südlichen Abhanges der österreichischen alpinen Molassezone. Heterogene, mittel- bis grobkörnige Sandsteine mit großen Klasten von Tonsteinen und Karbonaten bilden die Speichergesteine. Nach der Förderung wurde das Reservoir zu einem Erdgas-Speicher ausgebaut, der seit 2007 in Betrieb ist. Um die Mineralogie der Reservoirgesteine hinsichtlich der verschiedenen Zonen (Gas-, sekundär verwässerte-, Wasser und Übergangszone) und den Effekt der Bohrspülung auf die Formation besser zu verstehen, wurden verschiedene Analysen durchgeführt. Diagenetische Umwandlungen in den Sandsteinen sind Feldspat-Säume um detritäre Kalifeldspäte; authigene Quarzanwachssäume; Bildung von framboidalen Pyriten sowie spätere Lösung und Ausbildung von oktaedrischen Pyriten. Calcit- und Dolomit bilden die häufigsten Zemente, auch authigene Tonminerale konnten analysiert werden. Weiters kommt Glaukonit als frühe Bildung in Form von Säumen um diverse Körner vor. Hauptaugenmerk lag auf der Charakterisierung der authigenen Tonminerale in den verschiedenen Zonen. Hierfür wurden Proben der gasgesättigten, der Übergangs-, der sekundär verwässerten und der initialen Wasserzone analysiert. XRD – Analysen der <2 µm – Fraktionen zeigten Unterschiede in den verschiedenen Zonen. Eine Erhöhung der Kristallinität von Smektit, Chlorit und Illit von der gasgesättigten bis zur initialen Wasserzone und eine Zunahme des Tonmineralgehaltes konnten beobachtet werden. Die wichtigste Beobachtung hierbei ist, dass es in der gasgesättigten Zone offenbar keine quellfähigen Tonminerale gibt. Dies ändert sich in der Übergangszone, in der sich Smektite ausbilden. Der durch die Gasförderung steigende Wasserspiegel beeinflusst die Authigenese der Tonminerale in den Porenräumen. Innerhalb weniger Jahre nach der Wassersättigung kam es zur Neubildung von Tonmineralen. Die bereits existierenden beginnen zu rekristallisieren und aufweitbare Tonminerale erscheinen in der Übergangszone, wo primär keine vorhanden waren. Die Bohrspülung hatte nur wenig Einfluss auf die Reservoirgesteine. Aufweitbare Tonminerale vom äußersten Rand der Bohrkerne (ca. 1 cm) zeigten ein anderes Verhalten als jene von der Mitte der Bohrkerne. Smektite absorbieren Kalium aus der Spülung, was zu einer Verminderung des Zwischenschichtabstandes führt. Baryt aus der Spülung infiltrierte in die äußersten ca. 3 mm der Kerne. Man erkennt eine abnehmende Häufigkeit der Baryte vom Rand Richtung Mitte der Bohrkerne

Podzemní vody hluboké struktury regionálního rozsahu: Pasohlávky–Laa an der Thaya

The regions of South Moravia in Czech Republic and Lower Austria are well-known for their use of thermal mineral waters for balneological purposes. Mineral waters are exploited from a Jurassic aquifer by two about 1.5 km deep wells MUS-3G (Pasohlavky, Czech Republic) and Laa TH Nord 1 (Laa an der Thaya, Austria). This Jurassic aquifer buried below the Neogene foredeep overlies a crystalline basement of Bohemian Massif and continues to the southeast below the Western Carpathians. Jurassic sediments which are mainly composed of autochthonous carbonates increase their thickness in this direction due to the decline of the crystalline basement. Because of this decline, there are two developments of Jurassic sediments, the shallower on the northwest and the deeper on the southeast. The zone between these two developments is known as the Mušov transition zone. For sustainable mineral water resources development, a groundwater flow pattern and recharge are evaluated. This evaluation includes both the hydrogeologic structure of Jurassic carbonates and hydraulically continuous underlying and overlying rocks. Because of the considerable depth of this hydrogeologic structure, which ranges from 100 to 3 000 metres below sea level, this study was based mostly on archive reports related to deep wells at the study area. The extent of studied units was identified on well-log data and geophysical survey interpretation. The resulting groundwater level contour map is based on the spatial distribution of hydraulic heads ranging approx. from 180 to 220 metres above sea level (masl) that were derived from pressure and water density conditions at the Jurassic aquifer. The general direction of groundwater flow is from northwest and southeast to the drainage zone (hydraulic head approx. 170–190 masl) identified in the middle of the studied area, which is identical to a course of the Mušov transition zone and parallel to the course of Dyje river (water table 170–180 masl). The northwestern part of the studied hydrogeological structure also differs from the southeastern part in a lower total mineralization which indicates active  inflow of fresh water. The study was also enhanced by a spatial distribution of hydraulic parameters of all modelled units. These  parameters were derived from hydrodynamic tests. The hydraulic conductivity values for the major Jurassic aquifer range from  6,0×10-4 to 1,3×10-9 m/s. The occurrence of the higher hydraulic conductivity near the drainage zone indicates the presence of a well-developed drainage network

The GRETA project: the contribution of near-surface geothermal energy for the energetic self-sufficiency of Alpine regions

The Alpine regions are deeply involved in the challenge set by climate change, which is a threat for their environment and for important economic activities such as tourism. The heating and cooling of buildings account for a major share of the total primary energy consumption in Europe, and hence the energy policies should focus on this sector to achieve the greenhouse gas reduction targets set by international agreements. Geothermal heat pump is one of the least carbon-intensive technologies for the heating and cooling of buildings. It exploits the heat stored within the ground, a local renewable energy source which is widely available across the Alpine territory. Nevertheless, it has been little considered by European policies and cooperation projects. GRETA (near-surface Geothermal REsources in the Territory of the Alpine space) is a cooperation project funded by the EU INTERREG-Alpine Space program, aiming at demonstrating the potential of shallow geothermal energy and to foster its integration into energy planning instruments. It started in December 2015 and will last three years, involving 12 partners from Italy, France, Switzerland, Germany, Austria, and Slovenia. In this paper, the project is presented, along with the results of the first year of work

Geologisches Untergrundmodell des Molassebeckens in Österreich

The Molasse Basin in the northern foreland of the Alps covers Lower- and Upper Austria as well as Salzburg between the outline of the Bohemian Massif in the north and the Alpine frontal thrust in the south. However, sediments of the Molasse Basin reach far towards south beneath the Alpine Orogen. Increasing usage requirements in the Molasse Basin regarding mining, geothermal energy and storage of CO2 and natural gas have been the main driving force for creating a geological subsurface model of the respective area. The model can therefore form the basis for a common subsurface management framework in order to prevent possible conflicts over resources. The published subsurface model includes nine stratigraphic units of the Autochthonous Molasse, the Crystalline Basement of the Bohemian Massif with overlying, Paleozoic sediments as well as a model unit combing the Allochthonous Molasse, the Flysch Zone and the Helvetic superunit. The whole model covers an area of about 12,250 km² and reaches to a depth of -8,000 m below sealevel.Das Molassebecken im nördlichen Alpenvorland in Nieder- und Oberösterreich sowie in Salzburg, erstreckt sich an der Erdoberfläche von der Böhmischen Masse im Norden bis zur Alpenüberschiebungsfront im Süden. Im Untergrund reichen die Molassesedimente jedoch noch deutlich weiter nach Süden bis unter das alpine Orogen. Steigende Nutzungsanforderungen an das Molassebecken in den Bereichen Bergbau, Geothermie, Thermalwasser sowie Speicherung von Erdgas und CO2 waren ausschlaggebend dafür, ein geologisches Untergrundmodell dieses Gebiets zu erstellen. Dieses Modell soll als Grundlage für ein gemeinsames Untergrundmanagement dienen, um regionalen Ressourcenkonflikten vorzubeugen. Das hier vorliegende Untergrundmodell besteht aus den neun stratigrafischen Haupteinheiten der autochthonen Molasse, dem Kristallin der Böhmischen Masse mit paläozoischer Sedimentbedeckung sowie einem Modellkörper, welcher die allochthone Molasse, die Flyschzone und das Helvetikum umfasst. Das gesamte Modell besitzt eine laterale Ausdehnung von ca. 12.250 km² und reicht bis in eine Tiefe von -8.000 m unter Meeresspiegel.The model was created using the SKUA-GOCAD™ software suite by combining all published, geological information on the subsurface (geological maps, cross-sections, contour maps and geophysical data). Subsequently, relevant data of the investigation area were digitized and combined into a common 3D modelling environment, where they acted as data points for creating interpolated, geological surfaces using automatical and manual approaches. The modelled geological layers were exported as .DXF files from SKUA-GOCAD™. For more information about the underlying data please see the data description document

Hydrochemické vlastnosti zdrojů termálních minerálních vod v oblasti Pasohlávky – Laa an der Thaya

The South Moravian region of Pasohlávky and the Lower Austrian town of Laa an der Thaya belongs to the areas of intensive use of thermal mineral water for recreational and balneological purposes. Thermal mineral water is extracted from a deep-seated Jurassic aquifer, mainly composed of carbonates. These carbonates overlie the crystalline bedrock, which is dipping towards the southeast below the Outer Western Carpathians. Due to this trend, there are two developments of the Jurassic sediments that differ in their lithological composition and are vertically separated by the Mušov transition zone. To the northwest from this zone, there is a shallower carbonate development and in the southeast, there is a deeper development which is composed of permeable carbonates together with impermeable marls. The Neogene sediments of Carpathian foredeep are deposited on the top of the Jurassic carbonate structure. Thermal mineral water is exploited by two hydrogeological wells – Muš-3G (Pasohlávky, 1 455 m deep) and Laa Th N1 (Laa an der Thaya, 1 448 m deep) situated in the shallower carbonate part of the Jurassic aquifer. The aim of this study, that summarizes the important partial outputs of the cross-border project Interreg HTPO (Hydrothermal Potential of the Area, ATCZ167), is to specify and clarify the origin, genesis and the processes of water formation based on the hydrochemical evaluation of thermal mineral water. For this purpose, both the final reports of studied wells and especially results from newly performed analyses of stable isotopes of hydrogen δ2H and oxygen δ18O were used. The δ18O and δ2H values of water samples from the Muš-3G well varies from –12,77 ‰ to –12,03 ‰ and from –92,23 ‰ to –88,05 ‰, respectively, while water samples from the Laa Th N1 well are isotopically heavier with δ18O values ranging from –7,04 ‰ to –6,31 ‰ and with δ2H values ranging from –51,04 ‰ to –49,33 ‰. In the Pasohlávky region we suppose it is an isotopically depleted water that has infiltrated in the cold climatic period (glacial). Evaluation of the chemical composition revealed that although the thermal waters from both areas of the hydrogeological structure are of the same Na–Cl type, their total mineralization differs significantly. Lower total mineralization in the Pasohlávky area (approx. 2,2 g/L) is also associated with higher relative concentrations of bicarbonate ions (HCO3–) and atmogenic nitrogen, typically bound to infiltrated meteoric waters. The thermal water in this area is mostly of meteoric origin, mixed with primary marinogenic water. In the Laa an der Thaya region, there is water with higher total mineralization (approx. 11 g/L) and lower relative concentrations of HCO3–, which together with the results of isotope analyses indicates a higher content of primary seawater. The marinogenic origin of waters also confirms the presence of bromides and iodides. The process of mixing primary marine waters with infiltrated meteoric waters significantly contributes to the chemical composition of the studied waters in both areas, while the original marinogenic water type of Na-Cl is preserved

The potential of geological storage of CO2 in Austria: a techno-economic assessment

An impressive two-third or about 40GWh/y of electricity in Austria is produced from renewable energy sources, in particular hydro energy. For the remaining part the country depends on fossil fuels, which together with iron & steel production form the most CO2 intensive industries in Austria with a combined emission of just over 20Mt/y. According to the IEA, CO2 capture and geological storage (CCS) can reduce the global CO2 emission until 2050 by 17%. A correct assessment of CCS needs to start with the storage potential. Prior to this study, only general estimates of the theoretical capacity of Austrian reservoirs were available, thus, up until now, the realistic potential for CCS technology has not been assessed. Both for policy and industry, an assessment of the matched capacity is required, which is the capacity that actually will be used in CCS projects. This hurdle can be taken by applying a recently developed methodology (Welkenhuysen et al., 2013). This policy support system (PSS) consists of two parts, PSS Explorer and PSS III simulator. In brief, the methodology is based on expert judgements of potential reservoirs. These assessments can provide the best available data, including the expert's experience and possibly confidential data, without disclosing specific data. The geo-techno-economic calculation scheme PSS Explorer uses the expert input to calculate for each individual reservoir an assessment of the practical capacity (as probability density functions), in function of an acceptable price for storage. This practical capacity can then be used by the techno-economic PSS III simulator to perform advanced source-sink matching until 2050 and thus provide the matched reservoir capacity. The analysed reservoirs are 7 active or abandoned oil and gas reservoirs in Austria. The simulation of the electricity and iron & steel sector of Austria resulted in the estimation of the geological storage potential, taking into account geological, technological and economic uncertainties. Results indicate a significant potential for CCS in Austria and a very high probability for any CO2 storage activity. The assessment of the average practical capacity of the whole country is 120Mt at 15€/tCO2 of storage budget, while the average matched national capacity is 40Mt. Concerning the individual reservoirs, reservoir development probabilities generally lie between 20 and 30%. These numbers served as basis for a reservoir exploration ranking. Compared to current emissions, total storage capacity is at the low end, which is likely the main technical limiting factor for CCS deployment in Austria. Also, current policy seems not in favour of CCS. Storage capacity is however high enough to provide a significant contribution to the reduction of CO2 emissions in the country, in the order of a few million tonnes per year. Opportunities to combine CO2 geological storage and geothermal energy seem promising, but require additional evaluation. Welkenhuysen, K., Ramirez, A., Swennen, R. & Piessens, K., 2013. Ranking potential CO2 storage reservoirs: an exploration priority list for Belgium. International Journal of Greenhouse Gas Control, 17, p. 431-44

The potential of geological storage of CO2 in Austria: a techno-economic assessment

An impressive two-third or about 40GWh/y of electricity in Austria is produced from renewable energy sources, in particular hydro energy. For the remaining part the country depends on fossil fuels, which together with iron & steel production form the most CO2 intensive industries in Austria with a combined emission of just over 20Mt/y. According to the IEA, CO2 capture and geological storage (CCS) can reduce the global CO2 emission until 2050 by 17%. A correct assessment of CCS needs to start with the storage potential. Prior to this study, only general estimates of the theoretical capacity of Austrian reservoirs were available, thus, up until now, the realistic potential for CCS technology has not been assessed. Both for policy and industry, an assessment of the matched capacity is required, which is the capacity that actually will be used in CCS projects. This hurdle can be taken by applying a recently developed methodology (Welkenhuysen et al., 2013). This policy support system (PSS) consists of two parts, PSS Explorer and PSS III simulator. In brief, the methodology is based on expert judgements of potential reservoirs. These assessments can provide the best available data, including the expert's experience and possibly confidential data, without disclosing specific data. The geo-techno-economic calculation scheme PSS Explorer uses the expert input to calculate for each individual reservoir an assessment of the practical capacity (as probability density functions), in function of an acceptable price for storage. This practical capacity can then be used by the techno-economic PSS III simulator to perform advanced source-sink matching until 2050 and thus provide the matched reservoir capacity. The analysed reservoirs are 7 active or abandoned oil and gas reservoirs in Austria. The simulation of the electricity and iron & steel sector of Austria resulted in the estimation of the geological storage potential, taking into account geological, technological and economic uncertainties. Results indicate a significant potential for CCS in Austria and a very high probability for any CO2 storage activity. The assessment of the average practical capacity of the whole country is 120Mt at 15€/tCO2 of storage budget, while the average matched national capacity is 40Mt. Concerning the individual reservoirs, reservoir development probabilities generally lie between 20 and 30%. These numbers served as basis for a reservoir exploration ranking. Compared to current emissions, total storage capacity is at the low end, which is likely the main technical limiting factor for CCS deployment in Austria. Also, current policy seems not in favour of CCS. Storage capacity is however high enough to provide a significant contribution to the reduction of CO2 emissions in the country, in the order of a few million tonnes per year. Opportunities to combine CO2 geological storage and geothermal energy seem promising, but require additional evaluation. Welkenhuysen, K., Ramirez, A., Swennen, R. & Piessens, K., 2013. Ranking potential CO2 storage reservoirs: an exploration priority list for Belgium. International Journal of Greenhouse Gas Control, 17, p. 431-44

The GRETA project: the contribution of near-surface geothermal energy for the energetic self-sufficiency of Alpine regions

The Alpine regions are deeply involved in the challenge set by climate change, which is a threat for their environment and for important economic activities such as tourism. The heating and cooling of buildings account for a major share of the total primary energy consumption in Europe, and hence the energy policies should focus on this sector to achieve the greenhouse gas reduction targets set by international agreements. Geothermal heat pump is one of the least carbon-intensive technologies for the heating and cooling of buildings. It exploits the heat stored within the ground, a local renewable energy source which is widely available across the Alpine territory. Nevertheless, it has been little considered by European policies and cooperation projects. GRETA (near-surface Geothermal REsources in the Territory of the Alpine space) is a cooperation project funded by the EU INTERREG-Alpine Space program, aiming at demonstrating the potential of shallow geothermal energy and to foster its integration into energy planning instruments. It started in December 2015 and will last three years, involving 12 partners from Italy, France, Switzerland, Germany, Austria, and Slovenia. In this paper, the project is presented, along with the results of the first year of work