Vibratory Power Delivery to Rock During Rotary-Vibratory Drilling

1978 ◽  
Vol 100 (2) ◽  
pp. 179-187
Author(s):  
D. C. Ohanehi ◽  
L. D. Mitchell
Keyword(s):  
Complete System ◽  
Closed Form Solution ◽  
String Model ◽  
Element Model ◽  
Power Input ◽  
Drill String ◽  
Form Solution ◽  
Drilling Process ◽  
Drilling Mud ◽  
Mechanical Element

This paper outlines the theoretical description of the vibratory portion of the rotary-vibratory drilling process. A multiple mechanical element model is used to describe the drill string and rock-rock bit assembly. The drill string model has continuously distributed properties of mass, stiffness, and external drilling-mud damping. A closed form solution is developed using boundary condition matching at the end of each mechanical element. The solution is used to compute the power input to the system by a vibratory unit, the power delivered to the rock, and the power lost to the drilling mud through vibratory losses. From these data, efficiencies are computed. The analytical solution has been checked in parallel with a transfer matrix computer solution. The results are identical within computer precision. The analytical model is then applied to the study of the Drilling Research Incorporated (DRI) prototype drilling system and its test drilling parameters for the 1957 test drilling. Explanations of the limits of the increase in drilling rates to 2:1 are explored. The results are explored relative to the potential for increasing the drill penetration rates by system redesign. Conclusions are drawn concerning the most productive routes to be taken for rotary-vibratory drilling systems and for the vibratory driver. It has become clear that successful future downhole rotary-vibratory drilling rigs will require a complete system understanding, a complete system design, and a new concept in vibratory driver.

scholarly journals Dynamic Analysis and Vibration of Beam Inside Annulus for Ultra Short-Radius Water Jet Drilling

2012 ◽  
Vol 9 (1) ◽  
pp. 55 ◽  
Author(s):  
T Pervez ◽  
SA Al-Hiddabi ◽  
A Al-Yahmadi ◽  
AC Seibi
Keyword(s):  
Oil And Gas ◽  
Closed Form Solution ◽  
Oil And Gas Industry ◽  
Form Solution ◽  
Water Jet ◽  
Drilling Process ◽  
Drilling Mud ◽  
Gas Industry ◽  
Horizontal Drilling ◽  
Thrust Forces

Conventional water-jet nozzle systems have been developed and partially used in the oil and gas industry to drill horizontal sidetracks. However, this technique still presents a few shortcomings associated with tube buckling and water jet sagging. Due to these problems, the drilled hole deviates from the desired path and does not reach the target reservoir. The issue becomes more complex due to the continuously moving boundaries representing the borehole profile, which is, in turn, governed by the nozzle dynamics. A mathematical model representing the dynamics of water jet drilling confined in a borehole along with drilling mud is developed to predict the sagging phenomenon during the drilling process. The closed form solution of the governing equation is obtained for horizontal drilling in shallow formation layers. The solution shows the strong influence of nozzle vibration and the magnitude of thrust force at the nozzle tip on the profile and the diameter of drilled hole. For sidetrack drilling of greater than 400 m length, the magnitude of sagging is large enough to miss the target reservoir. Furthermore, the dril string buckles at certain magnitudes of thrust forces and penetration lengths.

scholarly journals A Method for the Design and Optimization of Nonlinear Tuned Damping Concepts to Mitigate Self-Excited Drill String Vibrations Using Multiple Scales Lindstedt-Poincaré

2021 ◽  
Vol 11 (4) ◽  
pp. 1559
Author(s):  
Vincent Kulke ◽  
Paul Thunich ◽  
Frank Schiefer ◽  
Georg-Peter Ostermeyer
Keyword(s):  
Multiple Scales ◽  
String Model ◽  
Element Model ◽  
Drill String ◽  
Installation Space ◽  
Drilling Process ◽  
Premature Failure ◽  
Design And Optimization ◽  
String Vibrations ◽  
Critical Dynamic

In downhole drilling systems, self-excited torsional vibrations caused by the bit-rock interactions can affect the drilling process and lead to the premature failure of components. Especially self-excited oscillations of higher-order modes lead to critical dynamic loads. The slim drill string design and the naturally limited drilled borehole diameter limit the installation space, power supply and lead to numerous potentially critical self-excited torsional modes. Consequently, small and robust passive damping concepts are required. The variety of possible downhole boundary conditions and potential damper designs necessitates analytical solutions for effective damper design and optimization. In this paper, two nonlinear passive damper concepts are investigated regarding design and effectiveness to reduce self-excited high-frequency torsional oscillations in drill string dynamics. Based on a finite element model of a drill string, a suitable minimal model based on the identified critical mode is generated and solved analytically using the Multiple Scales Lindstedt-Poincaré (MSLP) method. The advantages of MSLP compared to conventional MS methods are shown for this example. On the basis of the analytical solution, parameter influences are determined, and design equations are derived. The analytical results are transferred to self-excited drill string vibrations and discussed using time domain simulations of the drill string model.

Bending and free vibration analysis of foam-filled truss core sandwich panel

2016 ◽  
Vol 20 (5) ◽  
pp. 617-638 ◽  
Author(s):  
MP Arunkumar ◽  
Jeyaraj Pitchaimani ◽  
KV Gangadharan
Keyword(s):  
Free Vibration ◽  
Vibration Analysis ◽  
Sandwich Panel ◽  
Closed Form Solution ◽  
Free Vibration Analysis ◽  
Element Model ◽  
Form Solution ◽  
Numerical Comparison ◽  
Truss Core ◽  
Foam Filled

This paper presents the studies carried out on bending and free vibration behavior of truss core sandwich panel filled with foam typically used in aerospace applications. Equivalent stiffness properties for foam-filled truss core sandwich panel are derived by idealizing 3D foam-filled sandwich panel to an equivalent 2D orthotropic thick plate continuum. The accuracy of the derived elastic property is ensured by the numerical comparison of free vibration response of 3D and its equivalent 2D finite element model. The derived stiffness constants were used in closed form solution to evaluate the maximum deflection of the continuum. The results show that the free vibration and static behavior of the sandwich panel can be enhanced in due consideration to the space constraint by filling foam in the empty space of core. The results also reveal that triangular core foam-filled sandwich panel deflects less compared to other cores. From the free vibration analysis, effect of filling foam is effective in cellular and trapezoidal core.

Identification of cracks in an Euler–Bernoulli beam using Bayesian inference and closed-form solution of vibration modes

2020 ◽  
pp. 146442072096971
Author(s):  
Tianyu Wang ◽  
Mohammad Noori ◽  
Wael A. Altabey
Keyword(s):  
Finite Element ◽  
Bayesian Inference ◽  
Finite Element Model ◽  
Crack Detection ◽  
Closed Form Solution ◽  
Element Model ◽  
Form Solution ◽  
Vibration Modes ◽  
Vibration Data ◽  
The Finite Element Model

Over the past two decades, extensive research has been carried out in the field of structural health monitoring for damage detection in structural systems. Some crack detection methods are based on the finite element model of a beam and use vibration data are developed. These methods identify the crack by updating of the finite element model according to the vibration data of structure. This paper proposes a novel method for crack detection in Euler–Bernoulli beams based on the closed-form solution of mode shapes using Bayesian inference. The expression of vibration modes is derived analytically with the crack parameters as unknown variables. Subsequently, the Bayesian inference is used to obtain the probability density function of crack parameters and to evaluate the uncertainty of the modes. Finally, the method is applied to a series of numerical examples, including a beam with a single-crack and multi-cracks, to verify the effectiveness of this method.

Seismic Response of Unanchored Fluid-Filled Tanks Using Finite Elements

1992 ◽  
Vol 114 (1) ◽  
pp. 74-79 ◽  
Author(s):  
Wei Yi ◽  
S. Natsiavas
Keyword(s):  
Finite Elements ◽  
Seismic Response ◽  
Analytical Procedure ◽  
Equations Of Motion ◽  
Closed Form Solution ◽  
Element Model ◽  
Form Solution ◽  
Structural Domain ◽  
Hydrodynamic Response ◽  
Strong Ground

A finite element model is presented for the seismic response of liquid-filled tanks. This type of analysis is complicated for unanchored tanks, because the bases of these tanks separate from their foundations during strong ground motion. This changes the dynamic behavior of these structures considerably and may result in severe loading. The analysis starts by geometrically discretizing the shell structure using cylindrical finite elements. Then, application of Hamilton’s principle in the structural domain yields the equations of motion for the coupled fluid/structure system. The foregoing analytical procedure employs the closed-form solution for the hydrodynamic response problem, resulting in a compact system of equations of motion. Primary attention is paid to the formulation of the nonlinear base uplift problem. Effects due to shell and ground flexibility are also included.

scholarly journals Euler-Maclaurin Closed Form Finite State Space Model for a String Applied to Broadband Plate Vibrations

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Michael J. Panza
Keyword(s):  
Closed Form ◽  
State Space ◽  
State Space Model ◽  
Closed Form Solution ◽  
String Model ◽  
Form Solution ◽  
Space Model ◽  
Function Solution ◽  
Plate Vibrations ◽  
Finite State

The Euler-Maclaurin sun formula is applied to the infinite series Green's function solution in the space-time Laplace transform domain for the one dimensional wave equation for a string fixed at each end. The resulting approximate closed form solution is used to derive a single third order input-output ordinary differential equation to model the string dynamics. The average modal density of a plate is shown to be comparable to a string. A finite three state-space model is developed for the string and applied to the vibrations of a plate subjected to broadband random and impulse inputs. The applications include the direct problem of determining the response to a disturbance input and the inverse problem of identifying the disturbance input with a finite state observer based on the finite string model. Numerical simulations using many plate modes are obtained in the time and frequency domains and are used to compare the multimodal plate model to the finite string based model and to demonstrate how the finite string based model can be used to represent the multimodal vibrations of the plate.

A Finite Element Model of Skin Subjected to a Flash Fire

1994 ◽  
Vol 116 (3) ◽  
pp. 250-255 ◽  
Author(s):  
D. A. Torvi ◽  
J. D. Dale
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Closed Form Solution ◽  
Blood Perfusion ◽  
Element Model ◽  
Form Solution ◽  
Bioheat Transfer ◽  
Multiple Layer ◽  
Degree Burn ◽  
Flash Fire

A variable property, multiple layer finite element model was developed to predict skin temperatures and times to second and third degree burns under simulated flash fire conditions. A sensitivity study of burn predictions to variations in thermal physical properties of skin was undertaken using this model. It was found that variations in these properties over the ranges used in multiple layer skin models had minimal effects on second degree burn predictions, but large effects on third degree burn predictions. It was also found that the blood perfusion source term in Pennes’ bioheat transfer equation could be neglected in predicting second and third degree burns due to flash fires. The predictions from this model were also compared with those from the closed form solution of this equation, which has been used in the literature for making burn predictions from accidents similar to flash fires.

Stress Analysis of the Target Enclosure at the R14B Firing Range

1995 ◽  
Author(s):  
Aaron D. Gupta
Keyword(s):  
Stress Analysis ◽  
Structural Integrity ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Closed Form Solution ◽  
Element Model ◽  
Form Solution ◽  
Worst Case ◽  
Firing Range ◽  
Impulse Balance

Abstract A stress analysis of the target enclosure structure at the R14B firing range at Aberdeen Proving Ground (APG), MD, subjected to an internal blast and worst-case fragment impact was conducted to assure structural integrity and safe operation of the structure during tests. The reflected dynamic pressure loads due to explosive blast were estimated from the CONWEP explosion effects code developed by the U.S. Army Waterways Experiment Station and were modeled as exponentially decaying pressure pulses which could be approximated as triangular loads with equivalent impulses. Fragment impact loads are approximated from a momentum-impulse balance formulation as step loading functions. A closed-form solution of the equation of motion of a sidewall of the structure subjected to a triangular blast load was obtained and verified by a three-dimensional (3-D) finite element model.

Wave Number-Based Technique for Detecting Slope Discontinuity in Simple Beams Using Moving Test Vehicle

2017 ◽  
Vol 17 (06) ◽  
pp. 1750060 ◽  
Author(s):  
J. D. Yau ◽  
Judy P. Yang ◽  
Y. B. Yang
Keyword(s):  
Numerical Simulation ◽  
Closed Form Solution ◽  
Element Model ◽  
Beam Element ◽  
Form Solution ◽  
Wave Number ◽  
Test Vehicle ◽  
Promising Alternative ◽  
Alternative Approach ◽  
Slope Discontinuity

The wavelength characteristic is a useful clue for locating and assessing the severity of slope discontinuity in beams. In this study, the slope discontinuity of a beam is represented by an internal hinge restrained by elastic springs, and the wavelength of the beam is calculated indirectly from the vertical response of a test vehicle during its travel over the beam. The key parameters of the problem at hand are first unveiled using an approximate, closed-form solution for the response of the vehicle moving at low speeds over the bridge. Then a two-beam element model with slope discontinuity is formulated for the vehicle–bridge interaction (VBI) system for use in numerical simulation. In the examples, the wavenumber-based response of the test vehicle is used to identify the location and severity of the discontinuity in the beam. It is demonstrated that the wavelength-based technique presented herein by using the moving test vehicle as a moving sensor system offers a promising, alternative approach for damage detection in girder type bridges.

pH-Sensor Under Consideration for Multi-Sensor-Chip in Downhole Drilling Fluid Monitoring

2017 ◽  
Author(s):  
Jonathan Kühne ◽  
Frederic Güth ◽  
Heike Strauß ◽  
Yvonne Joseph ◽  
Pál Árki
Keyword(s):  
Optical Sensors ◽  
Drilling Fluid ◽  
Drill String ◽  
Glass Electrode ◽  
Drilling Fluids ◽  
Drilling Process ◽  
Ph Sensing ◽  
Drilling Mud ◽  
Ph Sensors ◽  
Drilling Muds

Modern drill strings for the exploration of oil and gas are equipped with a variety of sensor carrying devices such as Measurement While Drilling (MWD), Logging While Drilling (LWD), and Formation Testing While Drilling (FTWD). These devices generate a large amount of downhole data, such as the orientation of the well, drilling parameters e.g. weight on bit and torque, and formation properties. Appropriate telemetry systems are included in the drill string to transfer relevant downhole data in real time to the surface. Other data is stored in memories downhole for subsequent evaluation. However, drilling fluid properties are still monitored at the surface and their behavior under borehole conditions is predicted with hydraulic models. Commercial solutions for a direct downhole measurement of various drilling fluid parameters are rare, though they would increase drilling process safety and the knowledge about the behavior of drilling fluids under real bottomhole conditions. The pH has a significant influence on the properties of water-based muds and plays a role in the chemistry of oil-based muds as the water cut in the emulsion increases. Commercial pH-sensing devices, such as the glass electrode, and optical sensors are not appropriate for the pH measurement under bottomhole conditions. Fragility, the insufficient degree of miniaturization, the low temperature and pressure resistance due to the liquid reference electrolyte, and phenomena such as the alkaline error are certain drawbacks of glass electrodes. Often optical sensors often will not capture the whole pH scale and require the medium to be at least slightly transparent for light. The usage of pH-sensors based on EIS (electrolyte-isolator-semiconductor) structures is a possible application of chemical sensors for drilling fluid monitoring under in situ borehole conditions. This paper presents results from a study on the behavior of an EIS structure as a pH sensitive electrode measured vs. a commercial Ag/AgCl reference electrode in comparison with a commercial glass electrode. EIS structures are capacitive pH sensors where the sensing layer is generally a metal oxide on a semiconductor substrate. Measurements in basic drilling muds were conducted under constant temperature and atmospheric pressure while the drilling mud was steadily stirred. The mud was titrated from alkaline to acidic conditions with hydrochloric acid and the pH was measured after potential equilibration at the electrodes. The results show a general feasibility for the usage of the proposed sensor. There are still certain challenges to be overcome in the development of a robust and reliable pH-sensing device for complex fluids, such as drilling muds under high pressure/high temperature (HP/HT) conditions.

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