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  • 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.
1

Reservoir characterization and sequence stratigraphy of Permian San Andres platform carbonates, Fullerton Field, Permian Basin, West Texas

Helbert, Dana Kristin 21 October 2010 (has links)
The San Andres Formation (Permian, Guadalupian) is the most prolific oil reservoir in the Permian basin. However, despite more than 60 years of production, an estimated 70% of the original oil in place remains. Recovery of this huge resource requires a better understanding of facies and reservoir framework, which, in turn, must be accomplished using a rock-based reservoir characterization process. This high resolution correlation method is essential for understanding the complex heterogeneities found in shallow water platform carbonates. Steps in the construction of a rock-based reservoir model in the Fullerton San Andres Unit (FSAU) included (1) defining depositional facies and primary facies groups; (2) creating an outcrop depositional model; (3) integrating facies descriptions with gamma-ray and porosity log data; (3) defining field-wide high frequency sequences based on wireline logs and cycle stacking patterns; (4) developing a sequence-based reservoir framework and 3-dimensional reservoir architecture; (5) defining porosity and permeability relationships for facies groups based on rock fabric characteristics. In Fullerton Field, the San Andres Formation comprises high frequency cycles of upward shoaling shallow-marine carbonates. Studies of nine cores (1730 ft) in FSAU reveal four peritidal and five shallow subtidal depositional facies based on texture, fossil assemblages, and sedimentary structures. Peritidal facies are dominantly laminated carbonate mudstones, interpreted as deposited on an intermittently exposed tidal flat. Shallow subtidal facies are peloid and mollusk dominated wackestones and packstones, interpreted as deposited in a shallow protected lagoon. Cycle stacking patterns indicate four complete upward shallowing high frequency sequences. Comparison of high frequency sequences between cored wells shows a high degree of similarity in the overall generalized vertical sequence, especially in the proportions of peritidal and subtidal components within each sequence. Three-dimensional reservoir characterization, using 132 gamma ray and porosity logs, reveals that depositional sequences are largely flat-lying with local topographic variation identified as the fundamental influence on lateral facies distribution within the reservoir section. Integration of core and petrophysical data from surrounding fields places FSAU in the larger sequence stratigraphic framework of the Central Basin Platform. The regional depositional sequence formed a series of depositional environments ranging from intermittently exposed to open marine. San Andres facies developed during south-easterly progradation of shallow water tidal flat and sabkha sediments over a deeper open marine shelf. / text
2

Political and judicial strategies for the care of marine and coastal ecosystems. The case of Creole People in San Andrés Island, Colombia.

Núñez Riaño, Miguel Ángel January 2016 (has links)
This thesis illustrates how native populations exert a crucial ecological role through deliberate strategies in order to conserve and preserve marine and coastal ecosystems. The investigation identifies political and judicial practices of the Creole people that have contributed to care of ecosystems placed in the Caribbean Archipelago of San Andrés. To this regard, this study considers how the agency of Creole people has influenced the environmental structuring of islands and seas during 20th and 21st centuries. The result is an improved comprehension, through critical analysis of cultural and judicial discourses, of the current ecological state of the Archipelago.
3

Outcrop-constrained flow and transport models of reflux dolomitization

Garcia-Fresca, Beatriz, 1973- 23 March 2011 (has links)
Two hydrogeologic models explore reflux dolomitization using two outcrop datasets at different scales to constrain transient boundary conditions and heterogeneous petrophysical properties. A platform-scale petrophysical model of the Permian San Andres Formation was built from outcrop and subsurface data following a reservoir modeling approach that preserves outcrop heterogeneity and incorporates a sequence stratigraphic framework. This model was used as input for hydrogeological simulations of hypersaline fluid flow and solute transport during the accumulation and compaction of the platform. Boundary conditions change over time, as relative sealevel fluctuations drive sedimentation, depositional environment migration, topographic gradients, and location, size and salinity of the brine source. The potential volume and distribution of dolomite formed is inferred by a magnesium mass-balance. The composite result of reflux events at various orders of stratigraphic hierarchy is a complex dolomite pattern that resembles that observed on San Andres outcrops. Dolostone bodies across the platform may be generated by different combinations of favorable conditions, including proximity to the brine source, zones of higher permeability, permeability contrasts, and latent reflux. A meter-scale reactive transport model of the Albian Upper Glen Rose Formation simulates deposition of three high-frequency cycles punctuated by three brine reflux events. The simulator determines flow, solute and reactive transport along the flow paths, revealing the spatial and temporal distribution of calcite dissolution, and precipitation of dolomite and sulfate. The model recreates fully and partially dolomitized cycles within the time and lithological constrains on Glen Rose outcrops. Our results show that the distribution of dolomite within a high-frequency cycle may be the net result of intercycle processes, whereby dolomitizing fluids sourced from younger cycles flow across stratigraphically significant boundaries. We also show that variations in dolomite abundance and the unfulfilled dolomitization potential control the contemporaneous propagation of multiple dolomite fronts and the coalescence of discrete dolomite bodies. Results show that reflux is an effective and efficient mechanism to dolomitize carbonate formations that progresses simultaneously with sediment accumulation. Dolomitization is the cumulative result of many short-lived reflux events, sourced in different locations and times, and amalgamation of successive dolostone bodies. This model contrasts with previous studies that approached dolomitization of a carbonate platform as a discrete reflux event and current interpretations that relate dolomite bodies to their most immediate stratigraphic surfaces. / text
4

Bridging the Broadband Divide through Universal Service Funds : Key Principles for Broadband Connectivity Projects in Underserved Areas

Joshi, Raoul, Hammarström, Fredrik January 2013 (has links)
The rapid emergence of broadband, or always-on Internet, during the course of the last decade, has increased the importance of the so- called information society in urban and industrialized societies world- wide. Liberalized information and communications technology (ICT) market forces worldwide have however failed to supply these services to rural and low-income regions resulting in the so-called digital divide. One financial tool, adopted by many developing nations to drive broadband investments in underserved areas, is the universal service fund (USF), a public fund mainly levying its resources from ICT market players. USFs have previously been used to fund telecom networks but with the growing importance of broadband, structural and regulatory discrepancies are preventing USFs from adequately supporting broadband investments. Currently, little up-to-date academic theory exists within this field; thus, this thesis serves to outline principles that policy-makers and regulators need to consider when designing or reforming universal service fund mechanisms. The research is based on a series of qualitative country case studies investigating policy, procedural, and executional aspects related to USFs and rural broadband. Publicly available material has been complemented with interviews of stakeholders from various levels to establish a holistic empirical base upon which conclusions have been drawn. The conclusions outline principles governing public involvement in USFs, roles played by various stakeholders in the broadband ecosystem, and strategies for rural broadband network deployment. / Framfarten av bredband under det senaste årtiondet har ökat vikten av det så kallade informationssamhället i de industrialiserade och urbaniserade samhällen. Marknadskrafterna inom den liberaliserade informations- och kommunikationsindustrin har dock misslyckats med att göra dess tjänster tillgängliga till glesbefolkade och låginkomstregioner, vilket har lett till en digital klyfta. Ett finansiellt hjälpmedel som många utvecklingsländer har anammat för att påskynda bredbandsinvesteringar i regioner med få bredbandsuppkopplingar är fonder för samhällsomfattande tjänster (USF), som är en offentlig fond vilken får den största delen av sitt kapital genom en pålaga på intäkterna från aktörer inom informations- och kommunikationsindustrin. USF:er har tidigare använts för att finansiera telekomnätverk, men i takt med att bredbandets ökande genomslag i samhället har strukturella och regleringsmässiga problem med USF:erna uppdagats vilka hindrar dem från att effektivt stödja bredbandsinvesteringar. För närvarande finns lite akademisk teori på området, och sålunda syftar denna uppsatts till att tillhandahålla principer vilka beslutsfattare och regulatorer bör efterfölja vid utformning eller reformering av mekanismer för samhällsomfattande tjänster för bredband. Arbetet baseras på en serie kvalitativa fallstudier av länder med policy, procedurella och verkställande aspekter kopplade till USF:er i områden med få bredbandsuppkopplingar i fokus. Material tillgängligt för allmänheten har kompletterats med intervjuer av intressenter från olika organisations- och samhällsnivåer för att skapa en heltäckande empiri på området från vilka slutsatser har dragits. Slutsatserna innehåller principer som rör offentlig inblandning i USF:er, roller för samhällets olika intressenter i ett ekosystem för bredband, samt strategier för utbyggnad av bredbandsnätverk i glesbefolkade områden.

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