Rig-Assisted Snubbing: Drillpipe Pressure Control in MPD/UBD

2020 ◽  
Author(s):  
Jan Aage Aasen ◽  
Joakim Haram Svensson
Keyword(s):  
Axial Stress ◽  
Three Dimensional ◽  
Pressure Control ◽  
Mechanical Analysis ◽  
Normal Operation ◽  
Combined Effects ◽  
Wellhead Pressure ◽  
Design Calculations ◽  
As Stress ◽  
Helical Buckling

Abstract An important pressure control issue during live well work is the expulsion force acting on the drillpipe. Wellhead pressure multiplied by drillpipe sealing area in the blowout preventor must be overcome before entering the well. The highest snubbing force (compression) is applied when running the first joint into the well since pipe weight is at its lowest at this time. Focus of this paper is the mechanical analysis of the drillpipe as a well barrier element during live well entry. We look at normal operation (primary well barrier) and contingency (secondary well barrier). Load cases include critical unsupported buckling, helical buckling inside tubing guide, collapse and burst. In critical unsupported buckling there is no radial confinement of the pipe and the critical buckling limit is determined at the onset of lateral deflection. On the other hand, inside the tubing guide the pipe is allowed to buckle into a helix and the buckling limit is related to permanent corkscrewing of the pipe. Technical contributions in this paper include engineering design formulas for unsupported buckling and helical buckling. Also presented are experimental buckling results from pipe up to 3½ inch (8.9 cm) diameter. Design calculations for primary and secondary well barriers are explained and analyzed using a field case. All load calculations are based on zero neutral axial stress as stress reference datum, which produces a yield circle that is conveniently deployed for three-dimensional well tubular design. The use of the dimensionless yield circle is found to be an efficient method to assess helical buckling loading and the combined effects of pressure and axial stresses.

scholarly journals Analysis of Turn-to-Turn Fault on Split-Winding Transformer Using Coupled Field-Circuit Approach

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1314
Author(s):  
Cunxiang Yang ◽  
Yiwei Ding ◽  
Hongbo Qiu ◽  
Bin Xiong
Keyword(s):  
Low Voltage ◽  
Short Circuit ◽  
Three Dimensional ◽  
Great Influence ◽  
Normal Operation ◽  
Transient Field ◽  
Axial Forces ◽  
Leakage Field ◽  
Characteristics Analysis ◽  
Split Winding

The turn-to-turn faults (TTF) are also inevitable in split-winding transformers. The distorted leakage field generated by the TTF current results in large axial forces and end thrusts in the fault windings as well as affecting other branch windings normal operation, so it is of significance to study TTF of split-winding transformers. In this paper, the characteristics analysis of the split-winding transformer under the TTFs of the low voltage winding at different positions are presented. A 3600 KVA four split-windings transformer is taken as an example. Then, a simplified three-dimensional simplified model is established, taking into account the forces of the per-turn coil. The nonlinear-transient field-circuit coupled finite element method is used for the model. The leakage field distribution under the TTFs of the low voltage winding at different positions is studied. The resultant force of the short-circuit winding and the force of the per-turn coil are obtained. Subsequently, the force and current relationship between the branch windings are analyzed. The results show that the TTF at the specific location has a great influence on the axial windings on the same core, and the distorted leakage magnetic field will cause excessive axial force and end thrust of the normal and short-circuit windings. These results can provide a basis for the short-circuit design of split-winding transformer.

Mechanism of the Transition From In-Plane Buckling to Helical Buckling for a Stiff Nanowire on an Elastomeric Substrate

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Youlong Chen ◽  
Yong Zhu ◽  
Xi Chen ◽  
Yilun Liu
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Stretchable Electronics ◽  
Buckling Mode ◽  
Design And Optimization ◽  
Out Of Plane ◽  
Plane Direction ◽  
Plane Displacement ◽  
Helical Buckling ◽  
Selection Of

In this work, the compressive buckling of a nanowire partially bonded to an elastomeric substrate is studied via finite-element method (FEM) simulations and experiments. The buckling profile of the nanowire can be divided into three regimes, i.e., the in-plane buckling, the disordered buckling in the out-of-plane direction, and the helical buckling, depending on the constraint density between the nanowire and the substrate. The selection of the buckling mode depends on the ratio d/h, where d is the distance between adjacent constraint points and h is the helical buckling spacing of a perfectly bonded nanowire. For d/h > 0.5, buckling is in-plane with wavelength λ = 2d. For 0.27 < d/h < 0.5, buckling is disordered with irregular out-of-plane displacement. While, for d/h < 0.27, buckling is helical and the buckling spacing gradually approaches to the theoretical value of a perfectly bonded nanowire. Generally, the in-plane buckling induces smaller strain in the nanowire, but consumes the largest space. Whereas the helical mode induces moderate strain in the nanowire, but takes the smallest space. The study may shed useful insights on the design and optimization of high-performance stretchable electronics and three-dimensional complex nanostructures.

The Uneven Settlement Cause and Settlement Prediction of Xi Ying Sluice

2015 ◽  
Vol 733 ◽  
pp. 116-119
Author(s):  
Qing Yuan Zhu ◽  
Li Ting Qiu ◽  
Ting Jiang
Keyword(s):  
Three Dimensional ◽  
Normal Operation ◽  
Wall Structure ◽  
Construction Period ◽  
Settlement Prediction ◽  
Concrete Pile ◽  
Operation Period ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Design Construction

Xi Ying sluice built in Xishi River, Changzhou City, is a single span sluice with width of 6m. The chamber is pier wall structure of depressed reinforced concrete floor, when the chamber had a filling and discharging water during construction period, we found that the chamber appeared large uneven subsidence. According to the design, construction and other specific circumstances of Xi Ying sluice, by using three-dimensional finite element method to calculate and analyzed the settlement of the sluice, we studied on the genesis of the uneven settlement and predicted the settlement after the running. Analysis shows that the chamber of the uneven settlement is due to the jacking effect of concrete pile. The settlement has been basically completed caused by chamber weight, there will not be a substantial settlement; In the case of blocking water during operation period, chamber’s settlement increment outside the river side and inside the river side are respectively 0.3mm and 0.4mm; through processing, the settlement of chamber won’t affect the normal operation of sluice.

scholarly journals Numerical aspects for efficient welding computational mechanics

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 139-148
Author(s):  
Tarek Aburuga ◽  
Aleksandar Sedmak ◽  
Zoran Radakovic
Keyword(s):  
Residual Stresses ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Mechanical Analysis ◽  
Tensile Test Specimen ◽  
Integrity Assessment ◽  
Mass Scaling ◽  
Three Dimensional Models ◽  
Thermal Mechanical Analysis

The effect of the residual stresses and strains is one of the most important parameter in the structure integrity assessment. A finite element model is constructed in order to simulate the multi passes mismatched submerged arc welding SAW which used in the welded tensile test specimen. Sequentially coupled thermal mechanical analysis is done by using ABAQUS software for calculating the residual stresses and distortion due to welding. In this work, three main issues were studied in order to reduce the time consuming during welding simulation which is the major problem in the computational welding mechanics (CWM). The first issue is dimensionality of the problem. Both two- and three-dimensional models are constructed for the same analysis type, shell element for two dimension simulation shows good performance comparing with brick element. The conventional method to calculate residual stress is by using implicit scheme that because of the welding and cooling time is relatively high. In this work, the author shows that it could use the explicit scheme with the mass scaling technique, and time consuming during the analysis will be reduced very efficiently. By using this new technique, it will be possible to simulate relatively large three dimensional structures.

Development and Mechanical Characterization of a Collagen/Hydroxyapatite Bilayered Scaffold for Ostechondral Defect Replacement

2011 ◽  
Vol 493-494 ◽  
pp. 890-895 ◽  
Author(s):  
Francesca Gervaso ◽  
Francesca Scalera ◽  
Sanosh Kunjalukkal Padmanabhan ◽  
Antonio Licciulli ◽  
Daniela Deponti ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Sol Gel ◽  
Three Dimensional ◽  
Collagen Scaffold ◽  
Mechanical Analysis ◽  
Design Parameters ◽  
Compression Tests ◽  
Templating Method ◽  
Organic Part ◽  
Hydroxyapatite Scaffold

In this work a novel three-dimensional ostechondral substitute is proposed that is made of an inorganic/organic hybrid material, namely collagen/hydroxyapatite. The two components of the substitute have been characterized separately. The inorganic part, a hydroxyapatite scaffold, was fabricated by a polymer sponge templating method using a reactive sub-micron powder synthesized in our laboratory by hydroxide precipitation sol-gel route. The organic part, a collagen scaffold, was fabricated by a freeze-dying technique varying design parameters. Both the parts were analysed by scanning electron microscopy and their mechanical properties assessed by compression tests. The hydroxyapatite scaffold showed a high and highly interconnected porosity and a mechanical strength equal to 0.55 MPa, higher than those reported in literature. The collagen scaffolds were seeded by chondrocytes, processed for histology analysis and tested in compression. The biological tests proved the ability of the scaffolds to be positively populated by chondrocytes and the mechanical analysis showed that the mechanical strength of the scaffolds significantly increased after 3 weeks of culture.

scholarly journals The Effect of Implant Length and Diameter on Stress Distribution around Single Implant Placement in 3D Posterior Mandibular FE Model Directly Constructed Form In Vivo CT

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7344
Author(s):  
Akikazu Shinya ◽  
Yoshiki Ishida ◽  
Daisuke Miura ◽  
Akiyoshi Shinya
Keyword(s):  
High Stress ◽  
Three Dimensional ◽  
Clinical Situation ◽  
Mechanical Analysis ◽  
Fe Model ◽  
High Stress Concentration ◽  
Implant Placement ◽  
Implant Therapy ◽  
Mandibular First Molar

A three-dimensional (3D) finite element (FE) model of the mandibular bone was created from 3D X-ray CT scan images of a live human subject. Simulating the clinical situation of implant therapy at the mandibular first molar, virtual extraction of the tooth was performed at the 3D FE mandibular model, and 12 different implant diameters and lengths were virtually inserted in order to carry out a mechanical analysis. (1) High stress concentration was found at the surfaces of the buccal and lingual peri-implant bone adjacent to the sides of the neck in all the implants. (2) The greatest stress value was approximately 6.0 MPa with implant diameter of 3.8 mm, approx. 4.5 MPa with implant diameter of 4.3 mm, and approx. 3.2 MPa with implant diameter of 6.0 mm. (3) The stress on the peri-implant bone was found to decrease with increasing length and mainly in diameter of the implant.

scholarly journals The effective complex permittivity stability in filled polymer nanocomposites studied above the glass transition temperature

2018 ◽  
Vol 149 ◽  
pp. 01080 ◽  
Author(s):  
F. Elhaouzi ◽  
A. Mdarhri ◽  
M. Zaghrioui ◽  
C. Honstettre ◽  
I. El Aboudi ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Complex Permittivity ◽  
Dielectric Response ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Low Frequencies ◽  
Neat Polymer

The temperature effecton the dielectric response of nanocomposite at low frequencies range is reported. The investigated samples are formed by a semi-crystalline ethylene-co-butyl acrylate (EBA) polymer filled with three concentrations of the dispersed conducting carbon black (CB) nanoparticles. The temperature dependence of the complex permittivity has been analyzedabove the glass transition temperature of the neat polymer matrix Tg=-75°C. For all CB concentrations, the dielectric spectra follow a same trend in frequency range 100-106Hz. More interestingly, the stability of the effective complex permittivity ɛ=ɛ' -iɛ'' with the temperature range of 10-70°C is explored. While the imaginary part of the complex permittivity ɛ'' exhibits a slight decreasewith temperature, the real part ɛ' shows a significant reduction especially for high loading samples. The observed dielectric response may be related to the breakup of the three-dimensional structurenetwork formed by the aggregation of CB particles causing change at the interfaceEBA-CB.This interface is estimated bythe volume fraction of constrained polymer chain according to loss tangent data of dynamic mechanical analysis.

Three-Dimensional Pressure Controlled Vortex Design of a Turbine Stage

2012 ◽  
Author(s):  
Qingfeng Deng ◽  
Qun Zheng ◽  
Guoqiang Yue ◽  
Hai Zhang ◽  
Mingcong Luo
Keyword(s):  
Pressure Gradient ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Pressure Control ◽  
Turbine Stage ◽  
Stream Surface ◽  
Control Approach ◽  
Flow Losses ◽  
Pressure Controlled ◽  
Surface Thickness

A three-dimensional (3D) Pressure Controlled Vortex Design (PCVD) method for turbine stage design is proposed and discussed in this paper. The concept is developed from conventional Controlled Vortex Design (CVD) via pressure control approach and CVD technology. By specifying the static pressure and axial velocity distributions, the spanwise pressure gradient incorporated with pressure gradient in streamwise and azimuthal directions is moderated. Not only can profile loss profit from pressure control approach, but also secondary flow can be managed. The reasons for CVD are derived from stream surface thickness and stream surface twist. Through modifying stream surface thickness and inducing large stream surface twist, the secondary flow migrations are controlled properly and orderly. The relations of pressure control approach and CVD technology complement one another and finally lead to a well-posed flow pattern in turbine stage. The first stage redesign of a well-designed low pressure turbine demonstrates this technique application. A significant reduction of secondary flow losses and a corresponding increase of stage efficiency have achieved.

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