A Comparative Study of Soft String Vs Stiff String Models Application in Torque and Drag Analysis

2021 ◽  
Author(s):  
Nnaemeka Princewill Ohia ◽  
Stanley Toochukwu Ekwueme ◽  
Gabriel Ifeanyi Achumba ◽  
Ndubuisi Okechukwu Okereke ◽  
Ifeanyi Valerian Nwankwo ◽  
...  
Keyword(s):  
High Resolution ◽  
Survey Data ◽  
String Model ◽  
Drag Model ◽  
Continuous Survey ◽  
Partial Representation ◽  
Open Hole ◽  
Data Survey ◽  
Drag Models ◽  
String Models

Abstract Torque and drag models estimate downhole forces, torques and moments acting in wellbores and drillstring elements during drilling and completion operations. A comparison was made between soft string and stiff string torque and drag model using conventional survey data. Survey data needed for torque and drag modeling are provided by field surveys. Field survey can be conventional survey or continuous survey. Conventional survey is carried out every 90 to 100ft interval or more and only gives a partial representation of the actual wellpath, micro-doglegs and micro-tortuosities may not be fully captured with this survey. Continuous survey is carried out between 1 to 5ft intervals of the wellbore using high resolution survey tools and captures more the micro-doglegs and micro-tortuosities but more expensive than the conventional survey. Torque and drag simulations were performed using both Soft and Stiff String models for comparison using a novel software package. Data provided includes deviational survey data from conventional survey, drillstring/BHA data, and fluid rheological data. The torque and drag simulation produced results for hook loads and buckling while running-in-hole (RIH) and pulling-out-of-hole (POOH). Results from this study show that prior to buckling, results from soft string and stiff string model are almost identical with minimal differences within the range of 0.8% to 1.6% and these were achieved as open-hole friction factors (CHFF) from 0.1 to 0.25. High buckling risk was detected for OHFF of 0.3. When buckling occurs, the differences in results between the two models become very apparent. This paper showed that in order to use stiff string torque and drag model for a more realistic, representative and more accurate pre-buckling and post-buckling operations in a highly deviated well, a high resolution continuous survey is needed; this will capture more readily, the micro-doglegs and micro-tortuosities in the wellbore paths.

Using High-Resolution MWD Survey Data in Mud Removal Simulations for Effective Cementing Program Design

2019 ◽  
Author(s):  
Leida Cristina Monterrosa ◽  
Chuang Hwee Tay ◽  
Jose Martin Salazar
Keyword(s):  
High Resolution ◽  
Survey Data ◽  
Program Design

Choosing Your Pond: Location Choices and Relative Income

2020 ◽  
pp. 1-46 ◽  
Author(s):  
Nicolas L. Bottan ◽  
Ricardo Perez-Truglia
Keyword(s):  
Medical Students ◽  
Field Experiment ◽  
Survey Data ◽  
Revealed Preference ◽  
Information Provision ◽  
Relative Income ◽  
Choice Data ◽  
Location Choices ◽  
Income Distributions ◽  
Data Survey

Do individuals care about their relative income? While this is a long-standing hypothesis, revealed-preference evidence remains elusive. We provide a unique test by studying residential choices: individuals often must choose between places with different income distributions, and as a result they “choose” their relative income. We conducted a field experiment with 1,080 senior medical students who participated in the National Resident Matching Program. We estimate their preferences by combining choice data, survey data on perceptions and information-provision experiments. The evidence suggests that individuals care about their relative income and that these preferences differ across single and non-single individuals.

On the Biais Passé

2016 ◽  
pp. 337-366
Author(s):  
João Pedro Xavier ◽  
Eliana Manuel Pinho
Keyword(s):  
String Model ◽  
Ruled Surface ◽  
Ruled Surfaces ◽  
Descriptive Geometry ◽  
13Th Century ◽  
Aesthetic Value ◽  
Structural Efficiency ◽  
Stone Cutting ◽  
String Models

Among the famous dynamic string models conceived by Théodore Olivier (1793-1853) as a primary didactic tool to teach Descriptive Geometry, there are some that were strictly related to classic problems of stereotomy. This is the case of the biais passé, which was both a clear illustration of a special warped ruled surface and an example of how constructors dealt with the problem of building a skew arch, solving structural and practical stone cutting demands. The representation of the biais passé in Olivier's model achieved a perfect correspondence to its épure with Monge's Descriptive Geometry. This follow from the long development of representational tools, since the 13th century sketch of an oblique passage, as well as the improvement of constructive procedures for skew arches. Paradoxically, when Olivier presented his string model, the importance of the biais passé was already declining. Meanwhile other ruled surfaces were appropriated by architecture, some of which acquiring, beyond their inherent structural efficiency, a relevant aesthetic value.

A CFD Study of Existing Drag Models for Geldart A Particles in Bubbling Fluidized Beds

2014 ◽  
Author(s):  
Bahareh Estejab ◽  
Francine Battaglia
Keyword(s):  
Experimental Data ◽  
Fluidized Beds ◽  
Fine Particles ◽  
The Other ◽  
Particle Interactions ◽  
Model Group ◽  
Drag Model ◽  
Numerical Studies ◽  
Solid Phases ◽  
Drag Models

In this study, seven drag models are examined to determine how they affect fluidization behavior of Geldart A particles of biomass and coal. Notwithstanding the notable number of numerical studies to find the best drag model for larger particles, there is a dearth of information related to drag models for finer Geldart A particles. Additionally, to our knowledge, these drag models have not been tested with a binary mixture of Geldart A particles. Computational fluid dynamics was used to model the gas and solid phases in an Eulerian-Eulerain approach to simulate the particle-particle interactions of coal-biomass mixtures and compare the predictions with experimental data. In spite of the previous findings that bode badly for using predominately Geldart B drag models for fine particles, the results of our study reveal that if static regions of mass in the fluidized beds are considered, these drag models work well with Geldart A particles. It was found that the seven drag models could be divided into two categories based on their performance. One category included the Gidaspow family of drag models (Gidaspow, Gidaspow-Blend, and Wen-Yu) and the Syamlal-O’Brien drag model; these models closely predicted the experiments for single solids phase fluidization. For binary mixtures, however, the other drag model group (BVK, HYS, Koch and Hill) yielded better predictions.

scholarly journals Keck HIRES spectroscopy of SkyMapper commissioning survey candidate extremely metal-poor stars

2019 ◽  
Vol 485 (4) ◽  
pp. 5153-5167 ◽  
Author(s):  
A F Marino ◽  
G S Da Costa ◽  
A R Casey ◽  
M Asplund ◽  
M S Bessell ◽  
...  
Keyword(s):  
High Resolution ◽  
Galactic Halo ◽  
High Dispersion ◽  
Chemical Abundances ◽  
Data Survey ◽  
Current Sample

Abstract We present results from the analysis of high-resolution spectra obtained with the Keck HIRES spectrograph for a sample of 17 candidate extremely metal-poor (EMP) stars originally selected from commissioning data obtained with the SkyMapper telescope. Fourteen of the stars have not been observed previously at high dispersion. Three have [Fe/H] ≤ −3.0, while the remainder, with two more metal-rich exceptions, have −3.0 ≤ [Fe/H] ≤ −2.0 dex. Apart from Fe, we also derive abundances for the elements C, N, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, and Zn, and for n-capture elements Sr, Ba, and Eu. None of the current sample of stars is found to be carbon-rich. In general, our chemical abundances follow previous trends found in the literature, although we note that two of the most metal-poor stars show very low [Ba/Fe] (∼−1.7) coupled with low [Sr/Ba] (∼−0.3). Such stars are relatively rare in the Galactic halo. One further star, and possibly two others, meet the criteria for classification as a r-I star. This study, together with that of Jacobson et al. (2015), completes the outcomes of the SkyMapper commissioning data survey for EMP stars.

Surface Survey and Satellite Reconnaissance: Reconstructing the Urban Layout of Mashkan-Shapir

Iraq ◽  
2012 ◽  
Vol 74 ◽  
pp. 65-74
Author(s):  
Elizabeth C. Stone
Keyword(s):  
High Resolution ◽  
Survey Data ◽  
Satellite Imagery ◽  
Large City ◽  
City Wall ◽  
Recent Introduction ◽  
Surface Survey ◽  
High Resolution Satellite Imagery ◽  
The City

The recent introduction of irrigation around the site of Mashkan-shapir, together with the availability of high resolution satellite imagery, has resulted in the preservation of architectural traces which could not be recovered when the site was researched between 1987 and 1990. In spite of recent looting, these traces have allowed the identification of the location of the palace and the reconstruction of much of the street system of this city, including the connection points across the ancient canals. Moreover, the survey data recovered through past fieldwork can be related to these traces, allowing an understanding of the larger context for many of the activities at the site, especially burial and manufacturing. Together these data provide a detailed view of how an ancient Mesopotamian city was conceived—in this instance by Sin-iddinam, who transformed it from a small village to a large city by building the city wall.

Coupled Belt-Pulley Vibration in Serpentine Drives With Belt Bending Stiffness

2004 ◽  
Vol 71 (1) ◽  
pp. 109-119 ◽  
Author(s):  
Lingyuan Kong ◽  
Robert G. Parker
Keyword(s):  
Eigenvalue Problems ◽  
String Model ◽  
Bending Stiffness ◽  
Vibration Modes ◽  
Discrete Eigenvalue ◽  
Belt Drives ◽  
Design Variables ◽  
Moving Beam ◽  
Serpentine Belt ◽  
String Models

A method is developed to evaluate the natural frequencies and vibration modes of serpentine belt drives where the belt is modeled as a moving beam with bending stiffness. Inclusion of bending stiffness leads to belt-pulley coupling not captured in moving string models. New dynamic characteristics of the system induced by belt bending stiffness are investigated. The belt-pulley coupling is studied through the evolution of the vibration modes. When the belt-pulley coupling is strong, the dynamic behavior of the system is quite different from that of the string model where there is no such coupling. The effects of major design variables on the system are discussed. The spatial discretization can be used to solve other hybrid continuous/discrete eigenvalue problems.

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