Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 85 for “"Downhole"”.
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Borehole effects on downhole seismic measurements
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994.
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Abrasion-corrosion of downhole drill tool components
… PhD project entitled ‘Abrasion-corrosion of downhole drill tool components’. The objective of this project was to replicate the wear-corrosion mechanisms of tungsten carbide (WC)-based hardmetals and coatings occurring in downhole environments (pH 9-11) under controlled laboratory conditions, …
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Downhole vibration sensing by vibration energy harvesting
… vibration energy harvesting device for use in a downhole environment. First order models of the necessary components for a generic vibration energy harvester are presented and used to predict the most sensitive parameters for the design of energy harvesting systems. A subset of the design tools …
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Phase-controlled rectification for permanent-magnet downhole alternators
… rectification to be used with permanent-magnet downhole alternators. The design faces unique challenges imposed by the downhole environment. The thesis discusses the design, simulation, and construction of the rectifier. A high-side semi-bridge phase-controlled model is proposed. The model is …
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System Design of a High-Temperature Downhole Transceiver
… improving reliability. In addition, current downhole telemetry data rates are insufficient for supporting more sophisticated and higher resolution well-logging sensors. Increasing the data rates can also save the industry significant amount of time by decreasing the amount of well-logging …
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Downhole Gas Separator Performance in Sucker Rod Pumping System
… amount of gas entering into the pump is to use downhole gas separators. The main purpose of these devices is to facilitate agglomeration of gas bubbles so that they migrate upwards and can be released through the casing annulus. Design and selection of downhole gas separators is usually done …
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Integrated multiphase flow modeling in wellbore for downhole pressure predictions
… significance. One would ask why not deploy downhole pressure gauges to obtain P_wf readings. Unfortunately, it is not economical or practical to do so. The harsh in-situ conditions are not optimal for such gauges, resulting in high failure rates. Thus, the common practice is to apply …
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Fibre optic pressure sensor for downhole monitoring in the oil industry
… more important than ever. The availability of downhole information is seen to be the key to increasing oil-recovery efficiency, currently estimated to be 35% on average for North Sea oil-wells.<br/>Fibre-optic sensors have the potential to measure many downhole parameters. However, …
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Design of a High Temperature GaN-Based VCO for Downhole Communications
… This paper presents a high temperature VCO for downhole communication system. The proposed VCO is designed and prototyped using 0.25 μm GaN on SiC RF transistor which has extremely high junction temperature capability. Measurements show that the proposed VCO can operate reliably under ambient …
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A High Temperature Wideband Power Amplifier for a Downhole Communication System
… power amplifier (PA) has been designed for a downhole communication system operating at an ambient temperature of 230oC. GaN technology was chosen primarily due to its ability to function at a high junction temperature. The proposed PA was designed with Qorvo's T2G6003028-FL HEMT as it …
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Downhole Weight on Bit Prediction with Analytical Model and Finite Element Method
… are comparable to results obtained from measured downhole WOB (DOWB).
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Downhole Automation Using Spline, Catenary and Clothoid Curves Based on Minimum Wellpath Energy
… to designed well trajectory, an experimental downhole drilling automation is set up and applied. The criterion used to select the best curve between deviated point and target point is the minimization of well path energy. This criterion considers curvature and torsion together, which supplies …
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Seismic Site Response and Extraction of Dynamic Soil Behavior From Downhole Array Measurements
The presence of deep unconsolidated deposits in the upper Mississippi Embayment has an important impact on anticipated surface motions. PSHA-NL, probabilistic seismic hazard analysis with nonlinear site effects, can be used to estimate seismic hazard with the effect of deep deposits. This thesis …
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Numerical and analytical modelling of downhole seismic sources--the near and far field
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
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Design of a High Temperature GaN-Based Variable Gain Amplifier for Downhole Communications
… frequency (IF) variable gain amplifier (VGA) for downhole communications, which can operate up to an ambient temperature of 230 °C. The proposed VGA is designed using 0.25 μm GaN on SiC high electron mobility transistor (HEMT) technology. Measured results at 230 °C show that the VGA has a peak …
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A High Temperature RF Front-End of a Transceiver for High Speed Downhole Communications
… the field in many areas, such as well logging downhole telemetry systems, power networks, sensors, and actuators. In the past, the industry has managed to use the existing electronics at temperatures up to 150 oC. However, declining reserves of easily accessible natural resources have motivated …
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Evaluation of Site Response Analysis for Vertical Ground Motions in LS-DYNA Using Geotechnical Downhole
This study was motivated by the desire to conduct site-specific vertical site response analysis. The main body of knowledge in this field is limited to horizontal shaking, as such a goal of this study was to extend that knowledge to vertical shaking. Current practice for predicting vertical ground …
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