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INTEGRATED GEOPHYSICAL IMAGING OF SUBSURFACE GEOLOGIC CONDITIONS ACROSS A CONTAMINANT PLUME, MCCRACKEN COUNTY, KENTUCKYBlits, Cora A. 01 January 2008 (has links)
Over 7.8 km of seismic reflection data and 2 km of electrical resistivity data were acquired, processed, and interpreted during this multi-method geophysical study. Objectives included the definition of geologic conditions underlying a contaminant plume in McCracken County, western Kentucky, and the determination of the potential for structural control on the rate and direction of plume migration. Both geophysical methods indicate the presence of multiple high-angle normal faults outlining a series of asymmetric grabens ranging in width from 160 m to almost 300 m and striking between N40°E and N45°E. There was agreement between the two methods on fault location and degree of near-surface offset, with offsets of 1 to 2 m observed at 10 to 20 m below ground surface and 3 to 8 m observed at 20 to 30 m depth. Bedrock displacement was generally 2 to 3 times larger, with offsets of 10 to 26 m observed. The faults appear to have originated in the Paleozoic with predominantly normal reactivation occurring as recently as the Pleistocene. The fault strikes generally approximate the orientation of the northwestern contaminant plume. Observed offset of the Regional Gravel Aquifer may form a preferential flow path for contaminant migration.
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An Approach to Mapping of Shallow Petroleum Reservoirs Using Integrated Conventional 3D and Shallow P- and SH-Wave Seismic Reflection Methods at Teapot Dome Field in Casper, WyomingOkojie-Ayoro, Anita Onohuome 17 November 2007 (has links) (PDF)
Using the famous Teapot Dome oil field in Casper, Wyoming, USA as a test case, we demonstrate how high-resolution compressional (P) and horizontally polarized shear (SH) wave seismic reflection surveys can overcome the limitations of conventional 3D seismic data in resolving small-scale structures in the very shallow subsurface (< 100-200 m (~328-656 ft)). We accomplish this by using small CMP intervals (5 ft and 2.5 ft, respectively) and a higher frequency source. The integration of the two high-resolution seismic methods enhances the detection and mapping of fine-scale deformation and stratigraphic features at shallow depth that cannot be imaged by conventional seismic methods. Further, when these two high-resolution seismic methods are integrated with 3D data, correlated drill hole logs, and outcrop mapping and trenching, a clearer picture of both very shallow reservoirs and the relationship between deep and shallow faults can be observed. For example, we show that the Shannon reservoir, which is the shallowest petroleum reservoir at Teapot Dome (depth to the top of this interval ranging from 76-198 m (250-650 ft)) can only be imaged properly with high-resolution seismic methods. Further, northeast-striking faults are identified in shallow sections within Teapot Dome. The strike of these faults is approximately orthogonal to the hinge of Teapot Dome. These faults are interpreted as fold accommodation faults. Vertical displacements across these faults range from 10 to 40 m (~33 to 131 ft), which could potentially partition the Shannon reservoir. The integration of 3D and high-resolution P-wave seismic interpretation helped us determine that some of the northeast-striking faults relate to deeper faults. This indicates that some deeper faults that are orthogonal to the fold hinge cut through the shallow Shannon reservoir. Such an observation would be important for understanding the effect on fluid communication between the deep and shallow reservoirs via these faults. Furthermore, the high-resolution seismic data provide a means to better constrain the location of faults mapped from drill hole logs. Relocation of theses faults may require re-evaluation of well locations as some attic oil may have not been drained in some Shannon blocks by present well locations. Therefore our study demonstrates how conventional 3D seismic data require additional seismic acquisition at smaller scales in order to image deformation in shallow reservoirs. Such imaging becomes critical in cases of shallow reservoirs where it is important to define potential problems associated with compartmentalization of primary production, hazard mitigation, enhanced oil recovery, or carbon sequestration.
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Multi-Scale Neotectonic Study of the Clear Lake Fault Zone in the Sevier Desert Basin (Central Utah)Heiner, Brandon D. 21 January 2014 (has links) (PDF)
A multi-scale high-resolution geophysical and geological study was conducted in the Sevier Desert, central Utah, found within the Colorado Plateau-Basin and Range Transition Zone. The region is marked by with Quaternary volcanics and faulting as young as 660 yr B.P., with many fault scarps thought to have the potential for 7+ magnitude earthquakes. Three locations within the Sevier Desert which represent three different tectonic expressions of possible faulting at the surface were selected. These include a location found within surface sedimentation, a location with surface sedimentation and sub-surface basalts and a location with basalts, at the surface with very limited sedimentation. A suite of geophysical data were obtained including the use of P-wave, SH-wave, ground-penetrating radar (GPR). Auger holes, microprobe glass analysis, and mapping information were also completed in order to constrain and gain a more complete understanding of the sub-surface structure. These data were used to determine if there are sub-surface expressions of the possible surface scarps and if all the faults within the fault zone have the same structural style. The possible surface fault expressions were found to be connected to sub-surface fault expressions but with differing results within both sediments and basalts. Our data show that a multi-scale approach is needed to obtain a complete view of tectonic activity. The area faulting in the Sevier Desert penetrates at depth involving multiple complex styles that include some faulting that cuts recent lava flows and some that do not. The evidence also indicates that in at least some area faulting was episodic and others may be single events having implications on level of activity and hazard.
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DYNAMICKÁ ANALÝZA ZÁKLADOVÉ KONSTRUKCE V INTERAKCI S PODZÁKLADÍM / DYNAMIC ANALYSIS OF THE SOIL-FOUNDATION INTERACTIONMartinásek, Josef Unknown Date (has links)
Thesis deals with problems of the soil-structure interaction. In the theoretical part is described the approach to mathematical modeling of structure-foundation-soil interaction. The subsoil models are further described in detail, including the models with piles (both static and dynamics models). In the next chapter there is described the dynamics theory of the systems with single or more degrees of freedom. There is also an analysis of propagation, reflection and refraction of mechanical one-dimensional waves (P-wave, S-wave) and spatial waves (P- wave, SV-wave, SH-wave) and waves in homogeneous half-space (R-wave L-wave). The numerical analysis is logically sorted from hand calculation of the parameter change influence on the modal characteristics to complex computational FEM model of the machine with a foundation on piles placed in the spatial block of soil. Numerical studies aim to determine the influence of the subsoil model on the modal characteristics and thus confirm the absolute necessity of the subsoil model in tasks of dynamics. The next goal is to determine the appropriate key parameters of the computational model: the size of finite element, suitable shape of subsoil model, suitable inclination of boundary condition and suitable boundary conditions. For creating of set of computational models was used language APDL in conjunction with ANSYS software interface. All used input files are listed in the Annex.
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