Spiraled Boreholes: An Expression of 3D Directional Instability of Drilling Systems

Marck, Julien; Detournay, Emmanuel

doi:10.2118/173156-ms

Cited by 4 publications

(3 citation statements)

References 26 publications

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“…Thus, the scaled lateral force on the bit is expected to be of order O ð10 À2 F Ã Þ or less because of the small tilt of the bit on the borehole axis. Equating the expressions for the force and moment at the bit computed from the BHA model to those arising from the bit/rockinteraction leads, in general, to a system of coupled delay differential equations for the inclination and azimuth of the borehole (Perneder 2013;Marck and Detournay 2015). The delays, corresponding to the positions of the rotary-steerable-system pads and stabilizers, represent the spatial feedback embedded in the borehole trajectory.…”

Section: Model Of Borehole Propagationmentioning

confidence: 99%

“…However, this approach neglects the effect of the bit walk, the angle that quantifies the noncoaxiality between the lateral force and lateral penetration at the drill bit. The effect of the walk on the spiraling tendency of drilling systems was studied separately (Marck and Detournay 2015). With the assumption that the borehole is contained in a vertical plane, borehole spiraling degenerates into its 2D equivalent, borehole rippling.…”

Section: Model Of Borehole Propagationmentioning

confidence: 99%

“…These oscillations in the drilling direction essentially betray variations of the bit tilt, as the orientation of the bit axis remains almost constant. This follows from the fluctuating nature of the lateral force at the bit as the stabilizers compel the bottomhole assembly (BHA) to conform to the borehole geometry (Marck and Detournay 2015). Different analytical models were proposed to explain this mechanism and to identify the parameters that mostly influence its onset-namely, the configuration of the BHA, the wear and lateral aggressiveness of the drill bit, and the weight on bit (Pastusek and Brackin 2003;Downton 2007;Perneder 2013;.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Rotary-Steerable-System Design on Borehole Spiraling

Marck

Detournay

2016

SPE Journal

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The paper investigates the influence of the design of push-the-bit rotary-steerable systems (RSSs) on the tendency to drill spiraled boreholes by analyzing the directional stability of the bit trajectory. In this model, differences in RSS designs are accounted for conceptually by assigning a lateral stiffness to the RSS pads. This simple device, which introduces a dependence of the force on the pads upon the deflection of the bottomhole assembly (BHA) relative to the borehole axis, enables exploration of the influence of the actuation mechanism, with the RSS behaving at the ends of the spectrum either as a soft or as a stiff node of the drilling structure.According to this analysis, low pad stiffness has little consequence on the general behavior of the system. However, as the pad stiffness increases, any perturbation in the borehole geometry sensed by the pads alters the drilling direction of the bit and triggers, under certain conditions, self-excited oscillations in the borehole geometry. By increasing the transverse rigidity of the BHA in the vicinity of the bit, stiff RSS pads thus enhance the propensity of a drilling structure to drill spiraled holes and generate, if the system is directionally unstable, borehole oscillations with pitch that corresponds to the distance between the bit and the pads. In contrast, a directionally unstable BHA equipped with RSS characterized by a low stiffness produces spiraled holes with a wavelength corresponding to the distance between the bit and the first stabilizer.

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Section: Model Of Borehole Propagationmentioning

confidence: 99%

Section: Model Of Borehole Propagationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Rotary-Steerable-System Design on Borehole Spiraling

Marck

Detournay

2016

SPE Journal

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Analysis and Quantification of Wellbore Tortuosity

Bang¹,

Jegbefume²,

Ledroz³

et al. 2016

SPE Production &Amp; Operations

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Summary Small-scale wellbore tortuosity—variations in attitude on a length scale smaller than standard survey intervals of 30 m (100 ft)—is generally neglected because of its small effect on the final position of the well and its unclear relation to traditional dogleg severity (DLS). However, it is well-known that such tortuosity may have significant influence on the drilling process and on drilling efficiency. Furthermore, it is a crucial factor for the design and installation of completions and production equipment, because a highly tortuous wellbore section, depending on borehole diameter and tortuosity amplitude and along-hole distribution, may exert strong bending forces on such equipment, or high friction on moving parts. This paper describes a novel methodology for analyzing the tortuosity of openhole wellbores, casing, drillstring, and production tubing. Several related tortuosity parameters are described, and examples of application to field data are included. The methods use high-resolution survey data [measured depth (MD), inclination, and azimuth], which may, in principle, originate from any surveying tool or service capable of providing such data. The methodology requires input data from a single survey only. On the basis of a user-defined length as single external parameter, tortuosity can be analyzed on any length scale greater than approximately 10 times the input survey-data interval, and with a maximum resolution equaling twice the data interval. The processed parameters include relative elongation of a tortuous section compared with a straight-line section, transverse displacements from the straight line, and maximum available diameter for a downhole device caused by the small-scale bendings of the section. The results can be displayed as graphs vs. MD, or as 3D-rendered views of the actual wellbore or tubing shape. Results from various field cases are included, in which the tortuosity analysis was applied to high-resolution continuous gyro survey data collected in cased wellbores. In all the field cases, the novel methods revealed sections of considerable tortuosity that were either unnoticed, or located with unacceptably low accuracy, by conventional methods. These results led to re-evaluation of the planned locations for completion and production equipment. The characterization of the wellbore in terms of tortuosity on various length scales may be of crucial importance for the functionality and lifetime of permanently installed equipment. For example, identification of highly tortuous sections will aid the placement of rod-guide wear sleeves, increasing the rod and casing life and reducing the workover frequency. Another application is the identification of low-tortuosity sections in which downhole pumps or other equipment will not be subject to excess bending. In addition, the tortuosity results may help evaluate the drilling equipment and the drilling process.

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Assessing the Impact of Drilling Tools on Wellbore Quality Using Ultrasonic Borehole Imaging

Penman

Wong

Cooper

et al. 2021

Day 2 Wed, May 26, 2021

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A detailed visualization of borehole size and shape, both while drilling and prior to running casing, completions, or wireline logging equipment, is an essential requirement to minimize non-productive time (NPT) associated with poor borehole quality or wellbore stability issues. The required visualization is made possible using logging-while-drilling (LWD) high-resolution ultrasonic imaging technology, suitable for both water-based mud (WBM) and oil-based mud (OBM) systems. This paper provides borehole size and shape assessment from field deployments of a 4¾-in. ultrasonic calliper and imaging tool, illustrating the impact on borehole quality of various bottom-hole assembly (BHA) designs, including positive displacement mud motors (PDMs) and rotary steerable systems (RSS). The visualization of borehole quality enables features such as borehole spiralling and enlargement to be assessed and used as input into optimizing completions planning and formation-evaluation programs. In addition, the combination of high-resolution travel-time and reflection-amplitude images enables artefacts induced by drilling equipment, including RSS, to be identified and understood. High-resolution travel-time and reflection-amplitude images and 3D borehole profile plots are presented from multiple wells, showing how different drilling systems and logging parameters, including drillstring rotation and logging speeds, impact borehole quality. The relationship between the angular bend in the PDM and the impact it has on borehole spiralling is discussed. The LWD logs presented illustrate the factors that influence borehole quality and the methodology used to ensure that high-resolution images are available in both vertical and high-inclination wellbores, leading to the ability to reduce the NPT associated with wellbore stability issues. The observation and assessment of drilling artefacts and irregular borehole size and shape act as inputs into optimizing completion and logging programs, evaluating the optimal placement of packers and other completion equipment, and the design of the drill bit and BHA. The ability to collect high-resolution travel-time and reflection-amplitude ultrasonic images in both WBM and OBM, in wellbores ranging from 5¾ to 7¼-in., leads to significant improvements in the understanding of wellbore quality. Borehole size and shape can now be visualized in real time in either water or oil-based drilling fluids at a resolution capable of identifying all significant drilling-induced geometric artifacts. This allows the adjustment of drilling parameters to minimize NPT associated with common drilling hazards, the optimization of completion programs and wireline logging programs.

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Spiraled Boreholes: An Expression of 3D Directional Instability of Drilling Systems

Cited by 4 publications

References 26 publications

Influence of Rotary-Steerable-System Design on Borehole Spiraling

Influence of Rotary-Steerable-System Design on Borehole Spiraling

Analysis and Quantification of Wellbore Tortuosity

Assessing the Impact of Drilling Tools on Wellbore Quality Using Ultrasonic Borehole Imaging

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