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Pullback Force Evaluation of Pipes Installed via Horizontal Directional Drilling
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- Author / Creator
- Rabiei, Montazar
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Since its first application in the 1970s, Horizontal Directional Drilling (HDD) has steadily become one of the fastest growing trenchless construction methods for utility and conduit installation under surface obstacles. This rapid growth in HDD application could not have been accomplished without major development in engineering and design procedures, which take into account the unique characteristics of this technology. As a result, the most current HDD design references, at least to some extent, rely on studies carried out in other industries, e.g., oil well drilling and utility cable installation. These adoptions are often made without making proper adjustments, leading to inaccurate pipe designs. This dissertation aims to identify and address the shortcomings that exist in current pullback determination methods during pipe installation by HDD. Throughout the study, special attention is paid to the investigation and refinement of the proposed procedures by the two reference design documents used widely in North America: the ASTM F1962 method and the Pipeline Research Council International (PRCI) method, used for HDPE and steel pipe design, respectively. The dissertation is heavily tilted toward investigating the pipe-drilling fluid interaction since several studies have emphasized the necessity of refining the current practice of fluidic drag calculation. Two new methods for calculating fluidic drag are introduced: one applicable to power-law fluids and the other one for Herschel-Bulkley fluids. The latter accounts for pipe eccentricity and is based on the application of Finite Volume Method (FVM) to the HDD drilling fluid flow problem. Also, a series of simple methods for fluidic drag estimation are proposed, which are suitable for HDD practitioners to use and can be incorporated into future standards. For estimating the non-fluidic drag component of pullback force, two different models have been developed: one for steel pipes and the other for HDPE pipes. Unlike the PRCI method, the former doesn’t involve an iterative procedure and, contrary to the ASTM F1962 method, the latter is not limited to crossings with specific bore geometry. For verification of the developed methods and models, pullback data collected on different crossings has been used. The data is provided by The Crossing Company (TCC), the industry partner of the Consortium for Engineered Trenchless Technologies (CETT) at the University of Alberta, and collected on different project sites for crossings executed in Alberta, Canada. The new proposed models have been able to simulate the recorded pullback forces, while the PRCI method failed to do so. It has been observed that the fluidic drag changes almost linearly with the installation progress; therefore, simple methods based on adaption of the pipe annulus to a slot can be used for estimating the fluidic drag. Furthermore, the fluidic drag is not a direct function of hydrokinetic pressure and, as a result, methods like ASTM F 1962 fail to predict the fluidic drag changes accurately. The FVM results revalued that the effect of eccentricity on the drag is insignificant, and its effects can be disregarded for practical application. The new proposed methods in this dissertation enables the HDD contactors/practitioners to predict drilling fluid flow within bore hole during pipe installation operation, so they can fine-tune their plans for drilling fluid collection and recovery.
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- Graduation date
- Fall 2016
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.