Drill string axial vibration and sonic head analysis

Emtehani Jahromi, Kambiz (2012) Drill string axial vibration and sonic head analysis. Masters thesis, Memorial University of Newfoundland.

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    Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
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Abstract

This study contains several analyses about vibration generation devices and axial vibration in the drill string. Advanced Drilling Group (ADG) has been seeking new technologies in drilling to improve the rate of penetration (ROP), and in this regard several vibration generation devices for rotary drilling have been reviewed for further analysis. The Sonic Head Drill (SHD) is one of the most prominent drilling tools in shallow depth drilling, and is the focus of the first part of this study. This study attempts to determine if this tool can be used for laboratory and field tests, and if the concept of unbalanced masses used in the SHD can be successful in oil and gas drilling. In order to determine the feasibility and ease of use of the SHD, a series of tests and simulations were conducted in this thesis. A sonic head is surrounded by four isolators. These isolators are experimentally characterized and the force transmitted to the rock and the frame is predicted. Several other vibratory systems were also reviewed and a basic model of a vibratory system based on the SHD principle is proposed. The vibration generation device designed is 127 mm (5 inches) in diameter and 0.5 m long. It can generate 74.5 kN vibratory force at the frequency of 150 HZ compared to 100 kN for the SHD. The drill string transfers rotary and vibratory motion to a drill bit. Drill string vibration is a very prevalent phenomenon: it has a great effect on drilling engineering, and drill string resonance is the main reason causing drill string fatigue. The drill string is connected to the vibration generation device proposed in this study, and it is another purpose of this study to analyze the effect of vibration on the drill string. Possible solutions are explored on how a shock sub can be used to mitigate a vibration generated by a vibratory tool or by bit rock interaction. In this regard, a model of the drill string is generated for real oil drilling at higher depth in commercial simulation software. This model includes self-weight, buoyancy forces due to the drilling fluid and realistic boundary conditions. This drill string model is used to predict the vibration tool force transmission to the rock and to the surface. This model is then used to design isolators to mitigate the vibration transferred to the surface. The result of this analysis shows that weight on bit (WOB), damping and spring constant of a shock sub have strong effects on the amplitude of vibration for the surface equipment. By applying higher WOB, damping and spring constant this amplitude would be reduced dramatically.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/2350
Item ID: 2350
Additional Information: Includes bibliographical references (leaves 110-118)
Department(s): Engineering and Applied Science, Faculty of
Date: 2012
Date Type: Submission
Library of Congress Subject Heading: Drill stem testing; Vibrators--Dynamics; Rock-drills--Vibration

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