This dissertation focuses on quantitatively interpreting the elastic properties of the Cranfield reservoir for CO₂ saturation. In this work, quantitative interpretation starts by examining the relationship between CO₂ saturation and the elastic properties of the reservoir. This relationship comes from a rock-physics model calibrated to measured well data. Seismic data can then be inverted using a model for CO₂ saturation and rock-property estimates. The location and saturation of injected CO₂ are important metrics for monitoring the long-term effectiveness of carbon capture utilization and storage. Non-uniform CO₂ saturation is a contributing factor to both lateral and time-lapse changes in the elastic properties of the Cranfield reservoir. In the Cranfield reservoir, CO₂ saturation and porosity can be estimated from the ratio of P-wave velocity (Vp) to S-wave velocity (Vs) and P-impedance (Ip), respectively. Lower values of Ip for a given rock matrix often correlate to higher porosity. Similarly, for a given area of the reservoir, lower Vp/Vs frequently can be associated with higher CO₂ saturation. If a constant porosity from the baseline to the time-lapse survey is assumed, changes in Ip over time can be attributed to changes in CO₂ saturation in lieu of using Vp/Vs. Decreases in Ip between the baseline and time-lapse survey can be attributed to increases in CO₂ saturation. With a rock-physics model calibrated to the reservoir, Ip and Is from a vertical seismic profile were correlated to statistical ranges of porosity and CO₂ saturations. To expand the lateral interpretation of reservoir porosity and CO₂ saturation, the time-variant changes in Ip between baseline and time-lapse surface seismic datasets were compared to changes in CO₂ saturation calculated from the rock-physics model. Characterizing the CO₂ saturation of the Tuscaloosa sandstones helped to establish a workflow for estimating reservoir properties and fluid saturation from multiple types of geophysical data. Additionally, this work helped establish an understanding for how CO₂ injected into a reservoir alters and changes the elastic properties of the reservoir and the degree to which those changes can be detected using geophysical methods. / text

3D time-lapse seismics, also known as 4D seismics, have great potential for monitoring the migration of CO2 at underground storage sites. This thesis focuses on time-lapse analysis of 3D seismic reflection data acquired at the Ketzin CO2 geological storage site in order to improve understanding of the reservoir and how CO2 migrates within it. Four 3D seismic surveys have been acquired to date at the site, one baseline survey in 2005 prior to injection, two repeat surveys in 2009 and 2012 during the injection period, and one post-injection survey in 2015. To accurately simulate time-lapse seismic signatures in the subsurface, detailed 3D seismic property models for the baseline and repeat surveys were constructed by integrating borehole data and the 3D seismic data. Pseudo-boreholes between and beyond well control were built. A zero-offset convolution seismic modeling approach was used to generate synthetic time-lapse seismograms. This allowed simulations to be performed quickly and limited the introduction of artifacts in the seismic responses. Conventional seismic data have two limitations, uncertainty in detecting the CO2 plume in the reservoir and limited temporal resolution. In order to overcome these limitations, complex spectral decomposition was applied to the 3D time-lapse seismic data. Monochromatic wavelet phase and reflectivity amplitude components were decomposed from the 3D time-lapse seismic data. Wavelet phase anomalies associated with the CO2 plume were observed in the time-lapse data and verified by a series of seismic modeling studies. Tuning frequencies were determined from the balanced amplitude spectra in an attempt to discriminate between pressure effects and CO2 saturation. Quantitative assessment of the reservoir thickness and CO2 mass were performed. Time-lapse analysis on the post-injection survey was carried out and the results showed a consistent tendency with the previous repeat surveys in the CO2 migration, but with a decrease in the size of the amplitude anomaly. No systematic anomalies above the caprock were detected. Analysis of the signal to noise ratio and seismic simulations using the detailed 3D property models were performed to explain the observations. Estimation of the CO2 mass and uncertainties in it were investigated using two different approaches based on different velocity-saturation models.

The aim is to gather pollen sequences and derive from them synthetic information on past species distribution and Holocene vegetation history. Lonicera nigra was selected as a model taxa. The phylogeographic hypothesis that its Alpine and Carpathian populations survived the LGM in separate refugia is supported only by the Late-Glacial record. This shrub migrated rapidly from southern to central Europe during the warm oscilations of the Late Glacial. The synthesis of vegetation history was produced by applying the REVEALS model, which can filter out following factors influencing the relationship between pollen and vegetation: pollen taphonomy, pollen productivity and pollen dispersal. It was necessary to calculate and test those parameters, so the goals were partly methodical. Pollen productivity estimates are calculated within the Relevant Source Area of Pollen, which is influenced by vegetation structure. Subsequent validation of those values in the area of the REVEALS model 10000 km2 and selection of additional values for lacking taxa created the best set of parameters for the study area. The source fossil dataset for purposes of this synthesis is the newly developed Czech Quaternary Pollen database (PALYCZ). Non-direct multivariate analysis of pollen percentages including all taxa revealed a similarity...