An Experimental Study of Drill-String Vibration

1960 ◽  
Vol 82 (2) ◽  
pp. 129-135 ◽  
Author(s):  
I. Finnie ◽  
J. J. Bailey
Keyword(s):  
Experimental Study ◽  
Axial Force ◽  
Natural Frequencies ◽  
Drill String ◽  
Torsional Vibrations ◽  
Satisfactory Solution ◽  
String Vibration ◽  
Rotational Motions ◽  
First Time ◽  
Made In

This paper describes equipment which has been developed for the measurement of axial force, torque, and axial and rotational motions at the top of a drill string. Measurements made in two wells with this equipment represent the first time these quantities have been recorded during drilling. A large number of frequencies of vibration were found in the recordings. Some of these, particularly torsional readings, correlated with predicted natural frequencies, but many did not. Several explanations have been proposed for these “extraneous” frequencies, but no completely satisfactory solution is available. In addition, some interesting interrelations between axial and torsional vibrations were observed.

scholarly journals Development and Testing of a Block Hydrocyclone

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1577
Author(s):  
Alexandr Repko ◽  
Milan Sága ◽  
Boris Sentyakov ◽  
Vladislav Sviatskii
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Reynolds Number ◽  
Mathematical Models ◽  
High Strength ◽  
Fluid Consumption ◽  
Fluid Filtration ◽  
Fluid Movement ◽  
First Time ◽  
Made In

The study aimed to theoretically substantiate the efficiency of liquid purification and obtain corroborating experimental data for a hydrocyclone, consisting of several blocks. Mathematical models of the process of hydrodynamic fluid filtration were developed with the use of screw swirlers. The obtained mathematical models characterize all the main processes of fluid movement in various zones of the functioning of the hydrocyclone. Formulas for calculating the structures of hydrocyclone blocks are included. A block for swirling the flow of the liquid to be cleaned has been made in the form of a three-way screw. For the first time, wear-resistant and high-strength plastic ZEDEX ZX-324 has been used as a material. An experimental study was conducted and the change in the Reynolds number and the coefficient of fluid consumption was shown, using different constructions of the three-way screw. The research results confirmed the correctness and sufficiency of mathematical models for the development and production of block hydrocyclones.

An Analytical Study of Drill-String Vibration

1960 ◽  
Vol 82 (2) ◽  
pp. 122-127 ◽  
Author(s):  
J. J. Bailey ◽  
I. Finnie
Keyword(s):  
Analytical Study ◽  
Natural Frequencies ◽  
Graphical Method ◽  
Drill Pipe ◽  
Drill String ◽  
Trial And Error ◽  
String Vibration ◽  
Method Of Solution ◽  
Trial And Error Method ◽  
Error Method

Longitudinal and torsional vibrations in a drill string consisting of drill pipe and collars, and the boundary conditions at the ends of the string, are discussed. A trial-and-error method of solution for the natural frequencies is demonstrated. Since it is very lengthy, certain useful charts are then derived, and a graphical method of solution for the natural frequencies is developed. By use of this method the natural frequencies can be quickly and easily obtained. The influences of various parameters on the natural frequencies are considered.

Mosses and lichens of Shokalsky Island (Kara Sea, Yamal-Nenets Autonomous Area)

2020 ◽  
Vol 54 (2) ◽  
pp. 497-513 ◽  
Author(s):  
L. N. Beldiman ◽  
I. N. Urbanavichene ◽  
V. E. Fedosov ◽  
E. Yu. Kuzmina
Keyword(s):  
Plant Communities ◽  
Species Distribution ◽  
Arctic Tundra ◽  
Kara Sea ◽  
Lichenicolous Fungi ◽  
South West ◽  
West Part ◽  
First Time ◽  
Nenets Autonomous ◽  
Made In

We studied in detail a moss-lichen component of Shokalsky Island vegetation for the first time and identified 79 species of mosses and 54 species and 2 subspecies of lichens and lichenicolous fungi. All species of mosses and 23 species and 2 subspecies of lichens and lichenicolous fungi are recorded for the first time for the island. The study is based on collections made in South West part of the island, in arctic tundra. We also explored the participation of the mosses and lichens in the main types of plant communities and the species distribution in 10 ecotopes. The paper describes the noteworthy findings (Abrothallus parmeliarum, Aongstroemia longipes, Arthonia peltigerea, Caloplaca caesiorufella, Catillaria stereocaulorum, Ceratodon heterophyllus, Lecanora leptacinella, Sphagnum concinnum, S. olafii) and features of bryo- and lichenoflora of Shokalsky Island.

Damage detection of a flywheel shaft

2010 ◽  
Vol 7 ◽  
pp. 211-218 ◽  
Author(s):  
A.G. Khakimov
Keyword(s):  
Damage Detection ◽  
Natural Frequencies ◽  
Torsional Vibrations

Using three natural frequencies of torsional vibrations, it is possible to define the location and size of a transverse notch on the flywheel shaft.

NUMERICAL AND EXPERIMENTAL STUDY ON FREE VIBRATION OF DELAMINATED WOVEN FIBER GLASS/EPOXY COMPOSITE PLATES

2012 ◽  
Vol 12 (02) ◽  
pp. 377-394 ◽  
Author(s):  
J. MOHANTY ◽  
S. K. SAHU ◽  
P. K. PARHI
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Numerical Study ◽  
Shear Deformation Theory ◽  
Composite Plates ◽  
Fiber Glass ◽  
Number Of Layers

This paper presents a combined experimental and numerical study of free vibration of industry-driven woven fiber glass/epoxy (G/E) composite plates with delamination. Using the first-order shear deformation theory, an eight-noded two-dimensional quadratic isoparametric element was developed, which has five degrees of freedom per node. In the experimental study, the influence of various parameters such as the delamination size, boundary conditions, fiber orientations, number of layers, and aspect ratio on the natural frequencies of delaminated composite plates are investigated. Comparison of the numerical results with experimental ones shows good agreement. Fundamental natural frequencies are found to decrease with the increase in the delamination size and fiber orientation and increases with the increase in the number of layers and aspect ratio of delaminated composite plates. The natural frequency of the delaminated composite plate varies significantly for different boundary conditions.

scholarly journals Stroke Prevention in Atrial Fibrillation: Where are We Now?

2012 ◽  
Vol 6 ◽  
pp. CMC.S8976 ◽  
Author(s):  
Yousif Ahmad ◽  
Gregory Y.H. Lip
Keyword(s):  
Atrial Fibrillation ◽  
Stroke Prevention ◽  
Management Strategies ◽  
Bleeding Risk ◽  
Long Term Study ◽  
Risk Patients ◽  
First Time ◽  
Major Progress ◽  
Made In

Atrial fibrillation is the commonest arrhythmia worldwide and is a growing problem. AF is responsible for 25% of all strokes, and these patients suffer greater mortality and disability. Warfarin has traditionally been the only successful therapy for stroke prevention, but its limitations have resulted in underutilisation. Major progress has been made in AF research, leading to improved management strategies. Better risk stratification permits identification of truly low-risk patients who do not require anticoagulation and we are able to simplify ourevaluation of a patient's bleeding risk. The advent of novel anticoagulants means warfarin is no longer the only choice for stroke prophylaxis. These drugs circumvent many of warfarin's inconveniences, but only long-term study and use will conclusively demonstrate how they compare to warfarin. The landscape of stroke prevention in AF has changed with effective alternatives to warfarin available for the first time in 60 years—but each new option brings new considerations.

Effect of compact inclusion on the natural frequencies of vibrations of a pipe string in a well

2021 ◽  
pp. 73-77
Author(s):  
A.M. Svalov ◽  
Keyword(s):  
Asymptotic Expansion ◽  
Small Parameter ◽  
Natural Frequencies ◽  
Oscillation Period ◽  
Drill String ◽  
Analytical Relation ◽  
Longitudinal Vibrations ◽  
Bottom Hole ◽  
Tubing String ◽  
Analytical Relations

The influence of small-size inclusion of pipes in a well column on the natural frequency of its longitudinal vibrations is investigated. Using the asymptotic expansion in a small parameter, an analytical relation is obtained that describes the change in the period of the column oscillations in the form of some additional small term to the period of the homogeneous column oscillations. Numerical calculations show that the obtained analytical relations almost accurately describe the oscillation period of a column with a massive compact inclusion, while its difference from the oscillation period of a homogeneous column is within ~20%. The results obtained can be useful for preventing resonant phenomena in the drill string when drilling wells, as well as for optimal use of the longitudinal vibrations of the tubing string to influence the bottom-hole zones of producing wells.

A Modular Mechanism for Downhole Weight-on-Bit and Torque Reaction in Small Diameter Boreholes

2021 ◽  
pp. 1-15
Author(s):  
Anirban Mazumdar ◽  
Stephen Buerger ◽  
Adam Foris ◽  
Jiann-cherng Su
Keyword(s):  
Axial Force ◽  
Small Diameter ◽  
Field Testing ◽  
Drill String ◽  
Force Transmission ◽  
Drilling Performance ◽  
Weight On Bit ◽  
In Series ◽  
Mechanical Devices ◽  
Scalable Design

Abstract Drilling systems that use downhole rotation must react torque either through the drill-string or near the motor to achieve effective drilling performance. Problems with drill-string loading such as buckling, friction, and twist become more severe as hole diameter decreases. Therefore, for small holes, reacting torque downhole without interfering with the application of weight-on-bit, is preferred. In this paper we present a novel mechanism that enables effective and controllable downhole weight on bit transmission and torque reaction. This scalable design achieves its unique performance through four key features: 1) mechanical advantage based on geometry, 2) direction dependent behavior using rolling and sliding contact, 3) modular scalability by combining modules in series, and 4) torque reaction and weight on bit that are proportional to applied axial force. As a result, simple mechanical devices can be used to react large torques while allowing controlled force to be transmitted to the drill bit. We outline our design, provide theoretical predictions of performance, and validate the results using full-scale testing. The experimental results include laboratory studies as well as limited field testing using a percussive hammer. These results demonstrate effective torque reaction, axial force transmission, favorable scaling with multiple modules, and predictable performance that is proportional to applied force.

Ultrasonic Attenuation Peaks Near the Diffuse Transition Temperature in Solid Electrolytes with Fluorite Structure

1988 ◽  
Vol 135 ◽  
Author(s):  
M. O. Manasreh ◽  
D. O. Pederson ◽  
T. S. Aurora
Keyword(s):  
Transition Temperature ◽  
Solid Electrolytes ◽  
Ultrasonic Attenuation ◽  
Linear Thermal Expansion ◽  
Fluorite Structure ◽  
Relaxation Rates ◽  
Local Site ◽  
Anomalous Peak ◽  
First Time ◽  
Made In

AbstractMeasurements of the ultrasonic attenuation and velocity have been made in solid electrolytes with fluorite structure, PbF2, BaF2, and CdF2, from room temperature to temperature at or above the diffuse solid electrolyte transition temperature, Tc. The ultrasonic attenuation peaks observed in this class of materials are associated only with the ionic conductivity saturation rather than in combination with crystallographic phase transition found in many other solid electrolytes. The relaxation rates and Arrhenius activation energies for anion motion above the transition temperature were obtained from the temperature dependence of the ultrasonic attenuation and the theory of local site fluctuations. The ultrasonic attenuation peaks observed for the first time in CdF2was used to define the diffuse transition temperature in this material. An Anomalous peak is also observed in the linear thermal expansion coefficient of PbF2.

Experimental Study on the Axial Force of Shearer Drum Cutting Coal and Rock

2015 ◽  
Vol 8 (1) ◽  
pp. 70-78 ◽  
Author(s):  
Chenxu Luo ◽  
Hongxiang Jiang ◽  
Xinxia Cui
Keyword(s):  
Experimental Study ◽  
Axial Force
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