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Pressure Management of Drilling Fluid and Study of Overcut Ratio in Horizontal Directional Drilling
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- Author / Creator
- Gao, Bo
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Horizontal directional drilling (HDD) has become one of the leading technologies for the installation of underground utilities and other trenchless projects. However, some of the risks associated with HDD, such as hydraulic fracturing and drilling fluid loss, have a considerable impact on construction that may lead to time loss and increased project cost and are major challenges for the industry to overcome. To minimize the risk of hydraulic fracturing and fluid loss, a proper and effective drilling fluid pressure management system is necessary. Moreover, there is still a chance for engineers to develop better design guidelines by optimizing the construction process. During HDD pipe installation, the diameter of the borehole must be larger than the diameter of the product pipe in order to perform a successful pullback operation; and the ratio of borehole diameter to pipe diameter is known as the overcut ratio. As a result, this thesis is focused on two critical problems in HDD: pressure management and overcut ratio. Accordingly, three major aspects of pressure management of drilling fluid are addressed in this thesis: 1) estimation of maximum allowable and minimum required fluid pressures, 2) modeling of the annular pressure of drilling fluid, and 3) drilling fluid pressure management and monitoring. Maximum allowable prediction methods are categorized based on the approaches used for prediction. The authors also discuss three different rheological models for predicting annular pressure of drilling fluid and provide an overview of drilling fluid pressure management in HDD. Furthermore, the effect of overcut ratio on the forces acting on steel and polyethylene pipes during HDD pipe installation is discussed in this thesis. To characterize the effect of overcut ratio, total pullback force is assessed in separate components including fluidic drag and change in direction. Existing methods and standards to calculate total pullback force are investigated. Results indicate that total pullback force decreases with increasing overcut ratio with a higher rate in the case of steel pipes. Change in pullback forces is normalized and quantified as percentages for both steel and Polyethylene (PE) pipes. This approach can be used for a quick and simple evaluation of the total pullback forces when planning HDD. The results indicate an overcut ratio of 1.5 is suitable for steel pipe and an overcut ratio of 1.3 is suitable for PE pipe.
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- Graduation date
- Fall 2018
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.