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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.
31

Foolproof completions for high rate production wells

Tosic, Slavko 10 October 2008 (has links)
Operators, especially those managing production from deepwater reservoirs, are striving to produce hydrocarbons at higher and higher rates without exposing the wells to completion failure risk. To avoid screen failures, recent studies have favored gravel pack (GP) and high rate water pack (HRWP) completions over high-permeability fracturing (HPF), known in the vernacular as a frac&pack (FP) for very high rate wells. While a properly designed GP completion may prevent sand production, it does not stop formation fines migration, and, over time, fines accumulation in the GP will lead to increasing completion skin. Although, and not always, the skin can be removed by acidizing, it is not practical to perform repeated acid treatments on deepwater wells, particularly those with subsea wellheads, and the alternative has been to subject the completion to increasingly high drawdown, accepting a high skin effect. A far better solution is to use a HPF completion. Of course the execution of a successful HPF is not a trivial exercise, and frequently, there is a steep learning curve for such a practice. This work explains the importance to HPF completions of the well trajectory through the interval to be hydraulically fractured, for production, not execution, reasons. A new model quantifies the effect of the well inclination on the connectivity between the fracture and the well via perforations. Guidelines based on the maximum target production rate, including forecasts of multiphase flow, are provided to size the HPF completion to avoid common completion failures that may result from high fluid rate and/or fines movement. Skin model will be developed for both vertical and deviated wells. Once the HPF is properly designed and executed, the operators should end up with a long term low skin good completion quality well. The well will be safely produced at the maximum flow rates, with no need for well surveillance and monitoring.
32

Approche pour l'ordonnancement distribué de workflows dans le contexte d'entreprises virtuelles une méthodologie basée multi-agents pour la planification et l'éxécution de processus distribués /

Kanzow, Sebastian Amirat, Yacine. Djouani, Karim January 2004 (has links) (PDF)
Thèse de doctorat : Sciences. Informatique : Paris 12 : 2004. / Titre provenant de l'écran-titre.
33

Apport de la cytométrie en flux dans l'étude de la physiologie plaquettaire et de la modulation pharmacologique des fonctions plaquettaires

Hezard, Nathalie Nguyen, Philippe January 2004 (has links) (PDF)
Reproduction de : Thèse doctorat : Médecine. Hématologie.Biomolécules et dynamique cellulaire : Reims : 2004. / Bibliogr.
34

Modélisation et contrôle statistique de l'analyse cytométrique de la ploïdie en cancérologie

Guillaud, Martial. Chassery, Jean-Marc. Demongeot, Jacques January 2008 (has links)
Reproduction de : Thèse d'université : Génie biologique et médical : Grenoble 1 : 1993. / Titre provenant de l'écran-titre. Bibliogr. p. 209-221.
35

Sphères de comportement pour la modélisation et l'exécution de procédés flexibles

Guabtni, Adnene Godart, Claude. January 2007 (has links) (PDF)
Thèse doctorat : Informatique : Nancy 1 : 2007. / Titre provenant de l'écran-titre.
36

Analysis of a curved buoyant jet in an enclosure using LES

Badeau, Allen E. January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xxii, 177 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 151-154) and index.
37

Processing, flux pinning and recycling of Y-Ba-Cu-O bulk superconductors

Pathak, Sandeep Kumar January 2011 (has links)
No description available.
38

Time and space dependent neutron flux in an externally moderated spherical cavity

Forehand, Harry MacDonald, 1941- January 1973 (has links)
No description available.
39

Timestep selection during streamline simulation via transverse flux correction

Osako, Ichiro 30 September 2004 (has links)
Streamline simulators have received increased attention because of their ability to effectively handle multimillion cell detailed geologic models and large simulation models. The efficiency of streamline simulation has relied primarily on their ability to take large timesteps with fewer pressure solutions within an IMPES formulation. However, unlike conventional finite-difference simulators, no clear guidelines are currently available for the choice of timestep for pressure and velocity updates. That is why we need largely an uncontrolled approximation, either managed by engineering judgment or by potentially time-consuming timestep size sensitivity studies early in a project. This will clearly lead us to the lack of understanding of numerical stability and error estimates during the solution. This research presents a novel approach for timestep selection during streamline simulation that is based on three elements. First, we reformulate the equations to be solved by a streamline simulator to include all of the three-dimensional flux terms - both aligned with and transverse to the flow directions. These transverse flux terms are totally neglected within the existing streamline simulation formulations. Second, we propose a simple grid-based corrector algorithm to update the saturation to account for the transverse flux. Third, we provide a discrete CFL (Courant-Friedrich-Levy) formulation for the corrector step that leads to a mechanism to ensure numerical stability via the choice of a stable timestep for pressure updates. This discrete CFL formulation now provides us with the same tools for timestep control as are available within conventional reservoir simulators. We demonstrate the validity and utility of our approach using a series of numerical experiments in homogeneous and heterogeneous ¼ five-spot patterns at various mobility ratios. For these numerical experiments, we pay particular attention to favorable mobility ratio displacements, as they are known to be challenging to streamline simulation. Our results clearly demonstrate the impact of the transverse flux correction on the accuracy of the solution and on the appropriate choice of timestep, across a range of mobility ratios. The proposed approach eliminates much of the subjectivity associated with streamline simulation, and provides a basis for automatic control of pressure timestep within full field streamline applications.
40

New neutron detector using magnetically focused electrons for fast reactor neutron flux measurements

Abdul-Majid Alzaidi, Samir 12 1900 (has links)
No description available.

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