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Fragestellung: Die Omarthrose bewirkt eine progrediente Deformität des Schultergelenks sowohl humeral wie glenoidal. Obwohl primär für die Instabilitätsarthrose gedacht, wird die Samilson-Prieto-Klassifikation (SPK) basierend auf der Größe des inferioren Humerskopfosteophyten[zum vollständigen Text gelangen Sie über die oben angegebene URL], Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2019)

Petrophysical properties like porosity and permeability are key parameters for a safe long-term storage of CO2 but also for the injection operation itself. These parameters may change during and/or after the CO2 injection due to geochemical reactions in the reservoir system that are triggered by the injected CO2. Here we present petrophysical data of first ever drilled cores from a newly drilled well at the active CO2 storage site - the Ketzin pilot site in the Federal State of Brandenburg, Germany. By comparison with pre-injection baseline data from core samples recovered prior to injection, the new samples provide the unique opportunity to evaluate the impact of CO2 on pore size related properties of reservoir and cap rocks at a real injection site under in-situ reservoir conditions. After injection of 61 000 tons CO2, an additional well was drilled and new rock cores were recovered. In total 100 core samples from the reservoir and the overlaying caprock were investigated by NMR relaxation. Permeability of 20 core samples was estimated by nitrogen and porosity by helium pycnometry. The determined data are comparable between pre-injection and post-injection core samples. The lower part of the reservoir sandstone is unaffected by the injected CO2. The upper part of the reservoir sandstone shows consistently slightly lower NMR porosity and permeability values in the post-injection samples when compared to the pre-injection data. This upper sandstone part is above the fluid level and CO2 present as a free gas phase and a possible residual gas saturation of the cores distorted the NMR results. The potash-containing drilling fluid can also influence these results: NMR investigation of twin samples from inner and outer parts of the cores show a reduced fraction of larger pores for the outer core samples together with lower porosities and T2 times. The drill mud penetration depth can be controlled by the added fluorescent tracer. Due to the heterogeneous character of the Stuttgart Formation it is difficult to estimate definite CO2 induced changes from petrophysical measurements. The observed changes are only minor. Several batch experiments on Ketzin samples drilled prior injection confirm the results from investigation of the in-situ rock cores. Core samples of the pre-injection wells were exposed to CO2 and brine in autoclaves over various time periods. Samples were characterized prior to and after the experiments by NMR and Mercury Injection Porosimetry (MIP). The results are consistent with the logging data and show only minor change. Unfortunately, also in these experiments observed mineralogical and petrophysical changes were within the natural heterogeneity of the Ketzin reservoir and precluded unequivocal conclusions. However, given the only minor differences between post-injection well and pre-injection well, it is reasonable to assume that the potential dissolution-precipitation processes appear to have no severe consequences on reservoir and cap rock integrity or on the injection behaviour. This is also in line with the continuously recorded injection operation parameter. These do not point to any changes in reservoir injectivity.

The objective of this study is to investigate long-term effects of injected CO2 on pore size related parameters. Changes in porosity, pore geometry and distribution, effective permeability, and capillary entry conditions influence the development of static and dynamic storage capacity and injectivity. For the batch experiments core samples from the target reservoir horizon and its directly overlying cap-rock of the Triassic Stuttgart Formation at the Ketzin pilot storage site in Germany drilled in 2007 (observation well Ktzi 202) were exposed to pure CO2 and synthetic reservoir brine in corrosion-resistant, high-pressure autoclaves under in situ P-T conditions over various time periods. For the first run with reservoir sandstone, seven inner core section (Ø 50 mm x 100 mm) and additional rock fragments were stored in separate autoclaves for 40 months. After 15, 21, 24, and 40 months, respectively, all autoclaves were opened and samples were taken for mineralogical, geochemical, microbiological and petrophysical investigations. In a second run, three parallel siltstone samples were placed in autoclaves and exposed to CO2 and synthetic reservoir brine with run durations of 2, 4 and 6 months; a fourth cap-rock sample was exposed to N2 for 6 months and served as blind-run. The samples were investigated by NMR relaxation and mercury injection porosimetry (MIP). The NMR amplitude is related to fluid filled porosity. In addition, the distribution of NMR-T2 values reflects the pore sizes. The porosity of the connected pore system and the distribution of pore throats can be derived from the MIP. Based on the data, empirical models were used to estimate corresponding permeabilities as well as displacement, threshold, and critical pore pressure from the mercury data. The porosity data of the batch experiments determined by NMR and MIP are comparable and consistent with the logging data. The data of the reservoir experiments indicate only small changes of the pore size related properties. The distinguishment between natural, lithostratigraphic variability and experimentally induced, CO2 related changes is difficult. The second dataset of parallel siltstone samples show also only very small changes in values over time and no effect at the N2 experiment. In 2012, after injection of 61 000 tons CO2, an additional well (Ktzi 203) was drilled and new rock cores were recovered in October 2012. In total 100 core samples from the overlaying caprock and the reservoir horizon with traceable CO2 were investigated by NMR relaxation. Samples from inner and outer parts of the drill core were used in order to separate the influence of potash drilling fluid. The NMR data and derived rock properties are comparable to the pre-injection values determined for the older wells. Due to the heterogeneous character of the Stuttgart Formation it is difficult to estimate definite CO2 induced changes from petrophysical measurements. Based on present data, the changes in pore size related properties of the siliciclastic rocks of the Ketzin reservoir and cap-rock are only minor. These pore size related parameters are not significantly affected by pure CO2 with only marginal influence on reservoir capacity and injectivity. The integrity of the reservoir formation at Ketzin is not affected.

29 Sandstone samples from the CO2 storage pilot site at Ketzin, Germany were studied within the Framework of the COORETEC project. In batch experiments the pressure and temperature conditions of a saline aquifer of the Ketzin drilling (about 630m in depth) were realized. The petrophysical properties porosity, permeability and electric conductivity and the mineralogical composition were studied before and after each experiment to check for changes due to interaction of the partial saturated sandstones (3M NaCl) with water-saturated supercritical CO2 (scCO2). The experiments were performed in a temperature range between 70 to 90 C and pressure range from 9 to 12 MPa to simulate the typical temperature and pressure conditions of a saline aquifer. The total experimental duration was one month, all samples were analyzed for changes of the petrophysical properties every two weeks. Blank tests were made with Argon and fully saturated samples. The mineralogical composition of the untreated samples were analyzed with XRD an XRF. (Quartz 32 wt% to 41.5wt%, Anhydrite 0wt% to 14wt%, Hematite 0wt% to 36wt% and Feldspars 8wt% to 31wt%.) The samples are very heterogenic in composition and easily break parallel to natural ravines. The porosity ranges from 7% to 33%, permeability ranges from 9,57E-17m2 up to 1.18E13m2 and density ranges from 2,64g/cm3 to 2,75g/cm3 for untreated samples. Most samples, that were intact after the first experimental cycle, they showed a slight increase in both porosity and permeability, while density remained unchanged within the experimental error.

In order to investigate CO2-brine-rock interactions occurring at the Ketzin pilot storage site, core samples of the siliciclastic reservoir rock were exposed to pure CO2 and synthetic reservoir brine at simulated in-situ P-T conditions of 5 MPa and 40 °C. Autoclaves were opened and rock and fluid samples taken after 15, 21, 24 and 40 months, respectively. The samples were analysed for mineralogical and chemical composition and compared to baseline data of untreated samples. XRD data with Rietveld refinement show decreasing weight percentages for analcime, chlorite, hematite and illite. While plagioclase as well as K-feldspar both do not reveal a coherent trend over time, quartz exhibits increasing weight percentages in the same interval. On freshly broken rock fragments corrosion textures were found on plagioclase, K-feldspar and anhydrite surfaces of CO2-treated samples. BSE images of the respective samples indicate (intensified) alterations of feldspar minerals. EMPA data display a change in plagioclase composition from intermediate to sodium-rich and albite endmember compositions during CO2 exposure. Compared to the synthetic brine used for the experiments, sodium, magnesium and chloride concentrations increased slightly, while potassium, calcium and sulfate concentrations significantly increased. Potassium and calcium even exceed reservoir brine concentration levels. Experimental observations were reproduced using the reactive geochemical modeling code Phreeqc-2. The mineralogical and geochemical measurements imply preferred dissolution of calcium out of plagioclase next to dissolution of K-feldspar and anhydrite. Petrophysical data show tendentially increasing porosities and permeabilities that also suggest mineral dissolution during the experiments. Due to the heterogeneous character of the Stuttgart Formation it is often difficult to distinguish between natural, lithostratigraphic variability and CO2-related changes. Assuming thermodynamic equilibrium preliminary reactive geochemical modeling of the observed CO2-fluid-rock interactions shows that the measured evolution of fluid composition is consistent with precipitation of albite and dissolution of anhydrite and illite, respectively. In a next step, kinetic data have to be included into the model to determine changes over time. Based on experimental data, the integrity of the Ketzin reservoir is not significantly affected by CO2.