Field experiments for fracture characterization: studies of seismic anisotropy and tracer imaging with GPR

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dc.contributor.advisorWilson, Clark R.en
dc.creatorBonal, Nedra Danielle, 1975-en
dc.date.accessioned2008-08-28T23:57:34Zen
dc.date.accessioned2017-05-11T22:18:46Z
dc.date.available2008-08-28T23:57:34Zen
dc.date.available2017-05-11T22:18:46Z
dc.date.issued2007-12en
dc.description.abstractKnowledge of fracture orientation and density is significant for reservoir and aquifer characterization. In this study, field experiments are designed to estimate fracture parameters in situ from seismic and GPR (radar) data. The seismic experiment estimates parameters of orientation, density, and filling material. The GPR experiment estimates channel flow geometry and aperture. In the seismic study, lines of 2D data are acquired in a vertically fractured limestone at three different azimuths to look for differences in seismic velocities. A sledgehammer, vertical source and a multicomponent, Vibroseis source are used with multicomponent receivers. Acquisition parameters of frequency, receiver spacing and source-to-receiver offset are varied. The entire suite of seismic body waves and Rayleigh waves is analyzed to characterize the subsurface. Alford rotations are used to determine fracture orientation and demonstrate good results when geophone orientation is taken into account. Results indicate that seismic anisotropy is caused by regional faulting. Average fracture density of less than 5% and water table depth estimates are consistent with field observations. Groundwater flow direction has been observed by others to cross the fault trend and is subparallel to a secondary fracture set. In this study, seismic anisotropy appears unrelated to this secondary fracture set. Vp/Vs and Poisson's ratio values indicate a dolomite lithology. Sledgehammer and Vibroseis data provide consistent results. In the GPR experiment, reflection profiles are acquired through common-offset profiling perpendicular to the dominant flow direction. High frequency waves are used to delineate fluid flow paths through a subhorizontal fracture and observe tracer channeling. Channeling of flow is expected to control solute transport. Changes in radar signal are quantitatively associated with changes in fracture filling material from an innovative method using correlation coefficients. Mapping these changes throughout the survey area reveals the geometry of the flow path of each injected liquid. The tracer is found to be concentrated in the center of the survey area where fracture apertures are large. This demonstrates that spatial variations in concentration are controlled by fluid channel geometry.en
dc.description.departmentGeological Sciencesen
dc.format.mediumelectronicen
dc.identifier.oclc194248472en
dc.identifier.urihttp://hdl.handle.net/2152/3593en
dc.language.isoengen
dc.rightsCopyright © is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en
dc.subject.lcshFaults (Geology)--Texas--Austin Regionen
dc.subject.lcshRock deformation--Texas--Austin Regionen
dc.subject.lcshSeismic waves--Speeden
dc.subject.lcshAnisotropyen
dc.subject.lcshGround penetrating radaren
dc.subject.lcshGroundwater flow--Measurementen
dc.titleField experiments for fracture characterization: studies of seismic anisotropy and tracer imaging with GPRen
dc.title.alternativeStudies of seismic anisotropy and tracer imaging with GPRen
dc.type.genreThesisen

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