• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 379
  • 324
  • 71
  • 54
  • 16
  • 10
  • 8
  • 6
  • 5
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • Tagged with
  • 1041
  • 1041
  • 223
  • 189
  • 81
  • 77
  • 73
  • 71
  • 70
  • 69
  • 67
  • 67
  • 67
  • 61
  • 58
  • 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.
91

Natural gas hydrate production

Battah, Sam Jordan January 2002 (has links)
The concept which led to the establishment of the research in natural gas hydrate production, was born by Dr. Robert Amin (currently Professor of Petroleum Engineering at Curtin University and Chair of the Woodside Research Foundation) and Alan Jackson of Woodside Energy. The intended research in this field is to establish the viability of utilizing a synthesised natural gas hydrate as a means to allow a cheaper form of transportation of natural gas from the wellhead to the customer in direct competition with liquefied natural gas (LNG). Natural gas exists in ice-like formations called hydrates found on or under sea-beds and under permafrost. Hydrates trap methane molecules inside a cage of frozen water, where the amount of hydrates trapped is dependent on surrounding formation pressure. The amount of natural gas trapped in hydrates is largely unknown, but it is very large. A number of scientists believe that hydrates contain more than twice as much energy as all the world's coal, oil, and natural gas combined, hence making it a viable option of fuel in the 21st century, in a world constantly seeking cleaner sources of energy. The feasibility of production of natural gas hydrates on offshore installations and onshore facilities makes this development a viable option. As such this technology requires detailed research and development in a laboratory environment coupled with a pilot plant construction for commercial operation. Current estimates for onshore based facilities for the production of hydrates show a cost reduction of approximately 25% compared with LNG plants of the same energy capacity. / There are two major issues which require detailed research and development in order to progress this technology. First is the enhancement of the hydrates production by the use of other additives, and second, the continuous production at near atmospheric pressures. Other research related to transport methodology and re-gasification will be essential for the overall success of this technology, however, this work is outside the scope of this research.
92

The Feasibility of Natural Gas as a Fuel Source for Modern Land-Based Drilling Rigs

Nunn, Andrew Howard 2011 December 1900 (has links)
The purpose of this study is to determine the feasibility of replacing diesel with natural gas as a fuel source for modern drilling rigs. More specifically, this thesis (1) establishes a control baseline by examining operational characteristics (response, fuel usage, and cost) of an existing diesel-powered land rig during the drilling of a well in the Haynesville Shale; (2) estimates operational characteristics of a natural gas engine under identical conditions; and (3) draws a comparison between diesel and natural gas engines, determining the advantages and disadvantages of those fuel sources in drilling applications. Results suggest that diesel engines respond to transient loads very effectively because of their inherently higher torque, especially when compared with natural gas engines of a similar power rating. Regarding fuel consumption, the engines running on diesel for this study were more efficient than on natural gas. On a per-Btu basis, the natural gas engines consumed nearly twice as much energy in drilling the same well. However, because of the low price of natural gas, the total cost of fuel to drill the well was lowered by approximately 54%, or 37,000 USD. Based on the results, it is possible to infer that the use of natural gas engines in drilling environments is feasible, and in most cases, an economical and environmental advantage. First, when compared with diesel, natural gas is a cleaner fuel with less negative impact on the environment. Second, fuel cost can be reduced by approximately half with a natural gas engine. On the other hand, natural gas as a fuel becomes less practical because of challenges associated with transporting and storing a gas. In fact, this difficulty is the main obstacle for the use of natural gas in drilling environments. In conclusion, because of its minimal drawback on operations, it is recommended that in situations where natural gas is readily available near current market prices, natural gas engines should be utilized because of the cost savings and reduced environmental impact. In all other cases, particularly where transport and storage costs encroach on the cost benefit, it may still be advantageous to continue powering rigs with diesel because of its ease of use.
93

Viscosities of natural gases at high pressures and high temperatures

Viswanathan, Anup 17 September 2007 (has links)
Estimation of viscosities of naturally occurring petroleum gases provides the information needed to accurately work out reservoir-engineering problems. Existing models for viscosity prediction are limited by data, especially at high pressures and high temperatures. Studies show that the predicted viscosities of natural gases using the current correlation equations are about 15 % higher than the corresponding measured viscosities at high pressures and high temperatures. This project proposes to develop a viscosity prediction model for natural gases at high pressures and high temperatures. The project shows that commercial gas viscosity measurement devices currently available suffer from a variety of problems and do not give reliable or repeatable results. However, at the extremely high pressures encountered in high pressure and high temperature reservoirs, the natural gases consist mainly of methane as the hydrocarbon constituent and some non-hydrocarbon impurities. Available viscosity values of methane were used in the development of a correlation for predicting the viscosities of naturally occurring petroleum gases at high pressures and high temperatures. In the absence of measurements, this correlation can be used with some confidence.
94

Futures risk premia and price dynamics in energy industry

Dinçerler, Cantekin. January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.
95

Essays on energy economics research

Lin, Ning, doctor of economics 30 January 2012 (has links)
In the first chapter, I examine a variety of the factors that affect the price and demand of natural gas. Prior natural gas price research approaches utilized well-defined time series models. I have taken these historical approaches and explored an alternative approach to estimating the model- defined equilibrium market price based on the market clearing condition. Assuming that the natural gas market is a relatively efficient market, the market equilibrium price induced by the model should track the observed market price. A two-step estimation process includes - reduced formed regression estimations for each market component in the material balance equation, and solves for the market balance equation with identified coefficients and parameters for the market equilibrium price. The model results track the market price quite well, in both one period ahead forecasts and a simulated 36 months forecast case. The second chapter in the series "The Game that Drives the LNG Train" analyzes the strategies and decisions of major oil companies’ on selecting regasification terminal sites for importing liquefied natural gas (LNG) along North American coastlines and delivery of regasified gas into regional domestic markets. Each participating firm’s decision is extensive and complex, involving multi-years of capital and human investments. Furthermore, fierce competition exists among firms procuring LNG cargos and servicing the same set of demand areas, i.e. the North America market. This paper will attempt to condense the whole strategy and decision-making process into a simplified multistage model. The model will focus on exploring the strategic elements of decisions for each participant firm in the competition through a game-theory lens. Extending from previous work on tying, the third chapter seeks a more structured result on the relationship of pre-commitment and exclusion due to tying under a Hotelling framework. A three-stage model is set up, which includes a conditional pre-commitment stage and an entry decision stage preceding the third stage of pricing competition. The paper concludes that: first, exclusion is possible even with zero fixed cost, and it is executed by conditional pre-commitment of tying upon entry. Second, conditional pre-commitment of tying only occurs if entry can be excluded, otherwise, tying is not profitable as independent pricing upon entry. / text
96

Catalytic Combustion and NO Formation of Natural Gas

Qi, Huixiu January 2014 (has links)
As the world energy demand increases and the utilization of non-traditional fossil fuels becomes more attractive, natural gas, from shale gas and in gaseous and liquefied forms, becomes one of the most promising alternative fuels nowadays. The natural gas offers lower fuel production and transportation costs, a lower carbon content, a higher combustion efficiency and a greater applicability to most of existing power plants and combustion engines. Challenges exist, especially in improving its ignition characteristics and to further reduce its greenhouse gas and particulate matter emissions. To overcome these restraints, hydrogen addition, catalyst modification and fuel lean combustion have been investigated recently. In this thesis, the ignition and emission properties of methane and its mixtures with hydrogen additive are first studied in the mini-channel reactor. Numerical investigations have been performed using the CHEMKIN PRO software for pure methane and the mixtures of methane and hydrogen in non-catalytic and catalytic combustion. These effects of the hydrogen fractions, Pt-catalyst, wall temperature and inlet conditions on the ignition delay and NO formation are investigated. Available gas phase kinetics and heterogeneous surface reaction mechanisms in the literature are implemented and analyzed. As the second part of this thesis, natural gas combustion on a counter-flow burner is investigated experimentally and numerically, with a focus on NO formation. The NO profiles, measured by the FT-IR spectroscopy, are compared with model results from CHEMIKIN and with the GRI-Mech 3.0 mechanism. The formation mechanism of NO and effects of the different fuel/oxidizer ratios on the NO formation are investigated.
97

The on line determination of mercury in process streams using atomic spectrometry

Brahma, Noel Kumar January 2000 (has links)
On-line systems for monitoring mercury in liquid and gaseous production and waste streams have been developed, utilising atomic fluorescence spectrometry (AFS) as the basis for detection. Instrumentation has been designed for unattended continuous operation. Laboratory chemistries for the vapour generation of mercury, normally performed off-line in batch mode, have been adapted and optimised for continuous, flow-injection analysis for varying sample types and chemical forms of mercury. The system has typical analysis cycle of 7 minutes, a limit of detection of 10 pg ml ˉ¹ a linear range up to 100 µg ml ˉ¹ and has been applied in industrial environments for the continuous monitoring of mercury in incineration wastewater and sulphuric acid. The system was validated by on-site trials for periods of one week, during which time comparative off-line laboratory measurements showed good agreement. An automated system for monitoring mercury in natural gas streams has also been developed and validated by laboratory and on-site industrial trials. A heated pressure let-down system was designed in order to facilitate sampling of high-pressure gas streams without condensation of heavier fractions. The heated sampling line was interfaced with an automated system for trapping mercury, from variable volumes of gas, onto gold amalgamation traps, with subsequent desorbtion and analysis by AFS. The method detection limit for a 58 litre sample of natural gas was 30 pg m ˉ³ which was sufficient to determine residual mercury in natural gas streams even after mercury scrubbing had been performed. The system was validated by laboratory trials and spiking experiments during on-site trials at a gas processing facility, which resulted in complete installation and commissioning.
98

The effect of biological and polymeric inhibitors on methane gas hydrate growth kinetics

Al-Adel, Shadi, January 1900 (has links)
Thesis (M.Eng.). / Written for the Dept. of Chemical Engineering. Title from title page of PDF (viewed 2008/01/14). Includes bibliographical references.
99

Development of a liner-less composite CNG cylinder and improved mechanical properties of cylinder materials /

Iqbal, Kosar. January 2008 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 82-90). Also available in electronic version.
100

Vaporization of complex mixtures

Podbielniak, Walter Joseph, January 1928 (has links)
Thesis (Ph. D.)--University of Michigan, 1928. / Cover title. At head of title: Exhibit A.

Page generated in 0.1134 seconds