• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 79
  • 10
  • 7
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 108
  • 108
  • 108
  • 30
  • 20
  • 15
  • 15
  • 14
  • 13
  • 12
  • 12
  • 12
  • 11
  • 11
  • 10
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Tectono-stratigraphic and climatic record of the NE Arabian Sea

Calvès, Gérôme January 2009 (has links)
This study describes the tectono-stratigraphic and climatic record of the NE Arabian Sea during the Cenozoic.  Compilation of regional knowledge and subsurface observations has in this thesis provided new interpretations and insights into the records present along this passive margin.  The first is the rifting period (80-65 Ma) and the identification of a syn-rift volcanic sequence, comparable to other volcanic rifted margins.  This is followed by the record of a drift sequence (~65 Ma to present day), composed of extensive carbonate platforms and an infill sequence of siliciclastic deposits.  The analysed drift sequence (sink) is partly the result of the erosion of the hinterland (source) characterised by the India-Eurasia continent-continent collision.  Influence of regional climate and/or tectonic forces on the accumulation rate in the sink was tested, but not conclusive as the study area (Upper Indus Fan) covers only a limited part of the sedimentary record of the Indus Fan.  The thermal regime of the western margin of India is sparsely sampled, but once analysed, allows the definition of first order constraints on multiple rifting events.  The post-rift subsidence of the margin is slow and anomalous for >28 m.y. after break-up, potentially in relation with vigorous asthenospheric convection and a sharp ocean-continent boundary.  Past and present fluid flow is recorded in the sedimentary sequence of the Upper Indus Fan.  The first is related to gas hydrate occurrence and is the result of the migration of fluids by a plumbing system to the shallow subsurface, expressed by bottom-simulating reflections crosscutting stratal reflections.  A longer term fluid migration is recorded in this basin by the longest lived (~22 m.y.) mud volcano field recorded to date.

Investigation of the crust in the southern Karoo using the seismic reflection technique

Loots, Letticia 07 July 2014 (has links)
Several seismic reflection surveys were conducted in the late 1980s and early 1990s under the auspices of the SA National Geophysics Programme. These surveys targeted the Bushveld Complex, Limpopo Mobile Belt (Limpopo Province), Witwatersrand Basin, Vredefort Dome and the Beattie magnetic anomaly (BMA) in the Southern Karoo. The ~100 km seismic reflection profile described in this study (SAGS-03-92) covers the BMA, the Southern Cape Conductive Belt (SCCB) and the Karoo/Cape Fold Belt boundary. The profile runs from approximately Droëkloof in the south to Beaufort West in the north along the N12 national road. The profile was acquired in 1992, but the complete profile was not interpreted or published prior to this study. The purpose of this study is to successfully reprocess the data and to do a structural and stratigraphic interpretation in order to try and understand the geological history and processes that led up to the formation of the rocks in that area. SAGS-03-92 reveals a clear image of the crust in the southern Karoo. The crust is interpreted to be around 37 km thick in the area of investigation and can be classed into three parts: upper crust, middle crust and lower crust. The upper crust consists of the Karoo and Cape Supergroup rocks that dip slightly to the south. This interpretation has been confirmed by two deep boreholes (BH No. 3 and KW 1/67). The seismic fabric shows quite a strong character in the upper crust and the interpreted boundaries between the different lithologies (The Table Mountain, Bokkeveld and Witteberg Groups of the Cape Supergroup and the Dwyka, Ecca and Beaufort Groups of the Karoo Supergroup) are for the most part quite easy to identify. Within the Cape Fold Belt (CFB), however, the seismic character becomes distorted in such a way that it is very difficult to make out any features. This is possibly due to the severe faulting and folding that occurred when the CFB formed. An unconformity that can continually be followed throughout the profile (although it disappears in the south of the profile possibly due to deformation when the CFB formed) separates the upper crust from the middle crust and the unconformity is clearly indicated by a strong series of reflectors on the seismic profile. The middle crust is interpreted to consist of granitic-gneisses belonging to the Bushmanland Terrane (part of the Namaqua-Natal Belt (NNB)). The seismic profile suggests that the NNB gneisses continue beneath the Cape Fold Belt. The seismic fabric dips steeply to the north. The middle crust also hosts the source of the Beattie Magnetic Anomaly (BMA). There is an area of high reflectivity under the BMA on the seismic profile that differs significantly from the surrounding seismic character. This area is characterised by a beanshaped cluster of strong reflections dipping north and south. It is ~10 km wide, with a thickness of ~8 km and occurs at a depth of ~6 km to ~10 km. The lower crust is interpreted to consist of either granites belonging to the Areachap Terrane, Richtersveld or Kheis Province (NNB) or rocks belonging to the Kheis Province. The seismic fabric of the lower crust dips moderately to the south. The Moho is recognised at ~37 km depth at ~68 km from the south of the profile, but for the rest of the profile, it is unclear where the Moho is encountered. The research done for this study correlates well with work done under the auspices of Inkaba yeAfrica, especially the work done by Ansa Lindeque

High resolution seismic imaging of the near-surface : comparison of energy sources /

Xiang, Jianguang, January 2000 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 114-119.

Toward high definition reservoir characterization

Luca, Gheorghe, January 2001 (has links)
Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xi, 149 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 118-124).

MCMC algorithm, integrated 4D seismic reservoir characterization and uncertainty analysis in a Bayesian framework / Markov Chain Monte Carlo algorithm, integrated 4D seismic reservoir characterization and uncertainty analysis in a Bayesian framework

Hong, Tiancong, 1973- 11 September 2012 (has links)
One of the important goals in petroleum exploration and production is to make quantitative estimates of a reservoir’s properties from all available but indirectly related surface data, which constitutes an inverse problem. Due to the inherent non-uniqueness of most inverse procedures, a deterministic solution may be impossible, and it makes more sense to formulate the inverse problem in a statistical Bayesian framework and to fully solve it by constructing the Posterior Probability Density (PPD) function using Markov Chain Monte Carlo (MCMC) algorithms. The derived PPD is the complete solution of an inverse problem and describes all the consistent models for the given data. Therefore, the estimated PPD not only leads to the most likely model or solution but also provides a theoretically correct way to quantify corresponding uncertainty. However, for many realistic applications, MCMC can be computationally expensive due to the strong nonlinearity and high dimensionality of the problem. In this research, to address the fundamental issues of efficiency and accuracy in parameter estimation and uncertainty quantification, I have incorporated some new developments and designed a new multiscale MCMC algorithm. The new algorithm is justified using an analytical example, and its performance is evaluated using a nonlinear pre-stack seismic waveform inversion application. I also find that the new technique of multi-scaling is particularly attractive in addressing model parameterization issues especially for the seismic waveform inversion. To derive an accurate reservoir model and therefore to obtain a reliable reservoir performance prediction with as little uncertainty as possible, I propose a workflow to integrate 4D seismic and well production data in a Bayesian framework. This challenging 4D seismic history matching problem is solved using the new multi-scale MCMC algorithm for reasonably accurate reservoir characterization and uncertainty analysis within an acceptable time period. To take advantage of the benefits from both the fine scale and the coarse scale, a 3D reservoir model is parameterized into two different scales. It is demonstrated that the coarse-scale model works like a regularization operator to make the derived fine-scale reservoir model smooth and more realistic. The derived best-fitting static petrophysical model is further used to image the evolution of a reservoir’s dynamic features such as pore pressure and fluid saturation, which provide a direct indication of the internal dynamic fluid flow. / text

Modeling of seismic coda, with application to attenuation and scattering in southeastern Tennessee

Ogilvie, Jeffrey Scott 08 1900 (has links)
No description available.

True amplitude prestack depth migration /

Deng, Feng, January 2007 (has links)
Thesis (Ph.D.)--University of Texas at Dallas, 2007. / Includes vita. Includes bibliographical references (leaves 103-107)

Optimization of seismic least-squares inversion /

Silva Aristeguieta, Maria. January 1993 (has links)
Thesis (Ph.D.)--University of Tulsa, 1993. / Includes bibliographical references (leaves 92-97).

Nonlinear elastic wave inversion by blocky parameterization /

Shin, Chang Soo. January 1988 (has links)
Thesis (Ph.D.)--University of Tulsa, 1988. / Bibliography: leaves 121-123.

The determination of crustal structure in the Adelaide geosyncline using quarry blasts as seismic sources /

Shackleford, Peter Ronald James. January 1978 (has links) (PDF)
Thesis (M.Sc.) -- Department of Physics, University of Adelaide, 1979.

Page generated in 0.1922 seconds