A Physical and Numerical Modeling for Launching of Jackets (Case Study on Balal PLQ Platform)

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
M. R. Honarvar ◽  
Moharam D. Pirooz ◽  
Mohammad R. Bahaari
Keyword(s):  
Numerical Modeling ◽  
Physical Modeling ◽  
Oil Field ◽  
Physical Models ◽  
Lower Viscosity ◽  
The Difference ◽  
The Stability ◽  
Stability Of Structures ◽  
Similarity Laws

Platform structures are commonly utilized for various purposes including offshore drilling, processing, and support of offshore operations. A jacket is a supporting structure for deck facilities, stabilized by piles driven through it to the seabed. In a jacket design, operational and environmental loads are very important and must be intensively investigated to secure the stability of structures during their service life, as well as installation phase. The main purpose of this research is to evaluate the results of physical modeling for the launch operation of jackets from barge into the sea, as the most hazardous stage in the installation of a platform, and compare them to those of numerical modeling. Both physical and numerical modeling parameters are described and they are examined on a prototype platform, i.e., Balal oil field production and living quarter platform that is a 1700 tone, eight-legged jacket located in the center of Persian Gulf, some 100km distance from Iranian Lavan Island. It is found that both numerical and physical methods can describe the motion of the barge similarly well, but some differences are traced in the motion of jacket. The inequalities are, then, appeared to be due to the Froude-type parameters applied for modeling purpose. One notable fact investigated in this research is the necessity for choosing Reynolds–Froude type in the physical modeling of the launch, instead of Froude type. This is because, in addition to the importance of gravitational and inertial forces, the viscosity affects the drag hydrodynamic force, as well. It should be noted that viscosity and consequently drag coefficient in Froude type modeling cannot be quite applicable and this causes the difference observed between the results of physical and numerical modeling. Although there have been so many jacket launching designed and probably their physical models have been tested, but to the best of our knowledge from the literature, there was found no study on Reynolds–Froude physical modeling of jacket launch phenomenon. If one is interested in practicing a Reynolds-Froude physical modeling, it could be done either in a centrifuge test or by using a fluid with lower viscosity dependent on the scale of model, or even by finding a fluid (with new viscosity and new density) and a new gravity to have simultaneously the Froude and the Reynolds similarity laws satisfied.

A Physical and Numerical Modeling for Launching of Jackets: Case Study on Balal PLQ Platform

2007 ◽  
Author(s):  
M. R. Honarvar ◽  
Moharram D. Pirooz ◽  
Mohammad R. Bahari
Keyword(s):  
Numerical Modeling ◽  
Physical Modeling ◽  
Oil Field ◽  
Knowledge Based ◽  
Lower Viscosity ◽  
Operational Life ◽  
The Difference ◽  
The Stability ◽  
Stability Of Structures

Platform structures are commonly utilized for various purposes including offshore drilling, processing and support of offshore operations. A jacket is a supporting structure for deck facilities stabilized by leg piles through the seabed. In a jacket design, operational and environmental loads are very important and must be investigated intensively to secure the stability of structures during their operational life, as well as installation phase. The main purpose of this research is to evaluate and compare the results of physical and numerical modeling for the launch operation of jackets from barge into the sea, as the most hazardous stage in the installation of a platform. Both physical & numerical modeling basics are described and they are performed on Balal PLQ (Production and Living Quarter) platform that is one 8-legged, 1700-tone main jacket of Balal oil field, located in the center of Persian Gulf, some 100 kms distance from Iranian Lavan Island. It is found that both methods can describe the motion of the barge similarly well, but some differences are traced in the motion of jacket. Then, the inequalities are evaluated to be due to the Froude-type parameters chosen for modeling purpose. The most important result achieved in this research is the necessity of choosing Reinolds-Froude type for physical modeling of launching, instead of Froude-type. This is due to the effect of viscosity in drag hydrodynamic force in addition to the importance of gravitational and inertial forces. It should be noted that viscosity and consequently drag coefficient in Froude type modeling is not quite correct and causes the difference between the results of physical and numerical modeling. To our knowledge, based on the surveyed done in the literature, although there was no results found on the physical modeling of jacket launch to be addressed, but it seems that Reynolds-Froude modeling could be done either in a centrifuge test or by using a fluid with lower viscosity dependent on the scale of model.

scholarly journals A Novel TODIM with Probabilistic Hesitant Fuzzy Information and Its Application in Green Supplier Selection

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-26
Author(s):  
Xiaoli Tian ◽  
Meiling Niu ◽  
Jiangshui Ma ◽  
Zeshui Xu
Keyword(s):  
Weighting Function ◽  
Multiple Criteria Decision Making ◽  
Decision Makers ◽  
Sensitivity Analyses ◽  
Fuzzy Information ◽  
Probability Weighting Function ◽  
The Difference ◽  
The Stability ◽  
Gains And Losses

TODIM is a well-known multiple-criteria decision-making (MCDM) which considers the bounded rationality of decision makers (DMs) based on prospect theory (PT). However, in the classical TODIM, the perceived probability weighting function and the difference of the risk attitudes for gains and losses are not consistent with the original idea of PT. Moreover, probabilistic hesitant fuzzy information shows its superiority in handling the situation that the DMs hesitate among several possible values with different possibilities. Hence, a novel TODIM with probabilistic hesitant fuzzy information is proposed in this paper to simulate the perceptions of the DMs in PT. To show the advantages of the proposed method, a novel TODIM is combined with hesitant fuzzy information. Finally, a case study is carried out to demonstrate the feasibility of the proposed method, and a series of comparative analyses and the sensitivity analyses are used to show the stability of the proposed method.

scholarly journals Slopes Analyses - Case Study, Slope Stability of Bypass Project

2021 ◽  
Vol 4 (2) ◽  
pp. 34
Author(s):  
Diana Bardhi
Keyword(s):  
Fe Analysis ◽  
Parameter Study ◽  
Dilatancy Angle ◽  
Pressure Distributions ◽  
Strain Relationship ◽  
Simple Slope ◽  
Coulomb Model ◽  
The Difference ◽  
The Stability

The scope of this study was to compare various stability evaluation methods. Accordingly, most common LE approaches were compared with the advanced LE (M‐P) method. Similarly, the differences in FOS computed from LE and FE analyses were compared based on a simple slope considering various load cases. In addition, two real slopes in a case study were analysed for the recorded minimum‐maximum GWT, pseudo‐static and dynamic conditions. Moreover, the stability evaluations of these slopes were based on both LE (M‐P) and FE (PLAXIS) calculation approaches, which both utilized shear strength parameters from advanced triaxle tests. Similarly, Mohr‐Coulomb model was applied in both approaches. The following conclusions are hence derived based on the reported work on both idealized and real slopes. To fulfil one of the aims of the study, the LE based methods are compared based on the factor of safety (FOS) obtained for various load combinations. The comparison is mainly based on simplified slope geometry and assumed input parameters. Among the LE methods, the Bishop simplified (BS), Janbu simplified (JS) and Janbu GPS methods are compared with the Morgenstern‐Price method (M‐PM). These LE methods are well established for many years, and thus some of them are still commonly used in practice for stability analysis. Moreover, the M‐PM has been compared with results from the FE analyses. Compared with theFE (PLAXIS) analyses, the LE (M‐PM) analyses may estimate 5 – 14percent higher FOS, depending on the conditions of a dry slope and a fully saturated slope with hydrostatic pore pressure distributions. For fully saturated conditions in the slope, inaccurate computation of stresses in LE methods may have resulted in larger difference in the computed FOS. Since, the FE software is based on stress‐strain relationship, stress redistributions are surely better computed even for a complicated problem. This has been found one of the advantages in FE simulations. A parameter study shows that the application of a positive dilatancy angle in FE analysis can significantly improve the FOS (4 ‐ 10percent). On contrast, the shear surface optimization in LE (M‐PM in SLOPE/W) analysis results in lower FOS, and thus minimizing the difference in FOS compared with FE analysis

scholarly journals Numerical Analysis of the Width Design of a Protective Pillar in High-Stress Roadway: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
FuZhou Qi ◽  
ZhanGuo Ma ◽  
Ning Li ◽  
Bin Li ◽  
Zhiliu Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Energy Density ◽  
Large Deformation ◽  
High Stress ◽  
Vertical Stress ◽  
Pillar Width ◽  
Modeling Approach ◽  
Roadway Stability ◽  
The Stability

The width design of protective pillars is an important factor affecting the stability of high-stress roadways. In this study, a novel numerical modeling approach was developed to investigate the relationship between protective pillar width and roadway stability. With the 20 m protective pillar width adopted in the field test, large deformation of roadways and serious damage to surrounding rocks occurred. According to the case study at the Wangzhuang coal mine in China, the stress changes and energy density distribution characteristics in protective pillars with various widths were analysed by numerical simulation. The modeling results indicate that, with a 20 m wide protective pillar, the peak vertical stress and energy density in the pillar are 18.5 MPa and 563.7 kJ/m3, respectively. The phenomena of stress concentration and energy accumulation were clearly observed in the simulation results, and the roadway is in a state of high stress. Under the condition of a 10 m wide protective pillar, the peak vertical stress and energy density are shifted from the pillar to roadway virgin coal region, with peak values of 9.5 MPa and 208.3 kJ/m3, respectively. The decrease in vertical stress and energy density improves the stability of the protective pillar, resulting in the roadway being in a state of low stress. Field monitoring suggested that the proposed 10 m protective pillar width can effectively control the large deformation of the surrounding rock and reduce coal bump risk. The novel numerical modeling approach and design principle of protective pillars presented in this paper can provide useful references for application in similar coal mines.

Physical and numerical study of lateral diversion by three-layer inclined capillary barrier covers under humid climatic conditions

2014 ◽  
Vol 51 (12) ◽  
pp. 1438-1448 ◽  
Author(s):  
Tony L.T. Zhan ◽  
He Li ◽  
G.W. Jia ◽  
Y.M. Chen ◽  
D.G. Fredlund
Keyword(s):  
Numerical Modeling ◽  
Physical Modeling ◽  
Heavy Rainfall ◽  
Unsaturated Flow ◽  
Numerical Study ◽  
Climatic Conditions ◽  
Physical Models ◽  
Effective Length ◽  
Capillary Barrier ◽  
Lateral Diversion

Southern China has a humid climate and often receives rainfalls that are of high intensity and (or) long duration. This paper investigates the performance of an inclined three-layer cover with capillary barrier effect (CCBE) comprising silt, sand, and gravel, for usage under humid climatic conditions. Physical modeling tests were carried out to observe the response of the three-layer CCBE system to a continuous heavy rainfall of about 70 mm/h. The layered cover model, housed in a 2 m long and 1 m wide instrumented box, is made up of 0.2 m thick silt, 0.1 m thick sand, and 0.1 m thick gravel, and the inclination of the model is 1V:3H. The movement of wetting front, changes in soil suction, and the primary components of water balance were measured during the operation of the physical models. The experimental data was used to calibrate the hydraulic parameters of the numerical model using the unsaturated flow software, SVFlux. Numerical modeling was subsequently carried out on a 60 m long inclined CCBE system to investigate the effective length of lateral diversion under prolonged rainfall. The main findings of the experimental and numerical studies are as follows: (i) the physical model tests showed that the response of the three-layer CCBE system to a heavy rainfall of 70 mm/h was different from the previous observations on experiments where the rainfall was less than 1.6 mm/h; (ii) correlation between the physical modeling and the numerical modeling indicated anisotropic behavior with respect to the hydraulic conductivity in the unsaturated sand layer; (iii) the long inclined, three-layer CCBE system (i.e., 0.6 m thick silt, 0.2 m thick sand, and 0.2 m thick gravel) had an effective length of lateral diversion over 10 m for 30 days of prolonged rainfall (i.e., 1080 mm in total).

Representing Steam Processes With Vacuum Models

1980 ◽  
Vol 20 (03) ◽  
pp. 151-174 ◽  
Author(s):  
G.L. Stegemeier ◽  
D.D. Laumbach ◽  
C.W. Volek
Keyword(s):  
Physical Model ◽  
Physical Modeling ◽  
Full Scale ◽  
Oil Field ◽  
Hot Water ◽  
Physical Models ◽  
Actual Process ◽  
Scaled Model ◽  
Modeling Technology ◽  
Pattern Size

Abstract Scaled models of steam processes have contributed significantly to the design and implementation of many field projects. These models provide a means of answering pertinent questions, including the effect of (1) injection rate, (2) production pressure, (3) completion interval, (4) pattern size and type, (5) aquifers, (6) heterogeneities, and (7) steam quality. Parameters are presented for scaling up physical-model results to full scale and for relating physical-model results to full scale and for relating one oil field to another. These relationships are generated by casting the governing equations in dimensionless form. A set of similarity parameters then are determined by inspectional analysis. In physical models, unfortunately, it is not possible to physical models, unfortunately, it is not possible to match all similarity parameters. Consequently, based on engineering judgment, a set containing a reduced number of parameters, called scaling parameters, is generated that generally can be matched between scaled model and field prototype. Techniques to implement this scaling are discussed, including a description of the laboratory models, typical materials, and procedures for conducting the experiments. Results of model studies for Mt. Poso and Midway Sunset prototypes are presented. presented. Introduction Physical modeling technology has been developed to Physical modeling technology has been developed to the extent that detailed descriptions of steam processes can be provided for field projects in which processes can be provided for field projects in which the number of wells is large, patterns are irregular, or asymmetry occurs from dip or water influx. In many of these cases, sufficient complexity can be introduced to provide both prediction of overall response and specific guidance for operating policies on a well-by-well basis. The fine detail attainable in physical models arises from the large number of physical models arises from the large number of beads or sand grains, typically in excess of 10 million, that are used in the packed bed. By comparison, present-day numerical steam simulators are limited present-day numerical steam simulators are limited practically to about 1,000 grid blocks. Besides practically to about 1,000 grid blocks. Besides offering this capability of representing additional geometrical and geological complexity, the physical models have the advantage that physical phenomena are not constrained by specified relationships but are free to interact subject only to scaling factors. This additional insight can be important in new processes for which relationships are not known or are difficult to formulate. Limitations of physical models arise because of the unavailability of materials and fluids having physical properties that will satisfy all scaling requirements. properties that will satisfy all scaling requirements. Effects of compromises in scaling often can be observed with simple geometric configurations in mathematical simulators. Conversely, improved mathematical simulation often is possible after determining important parameters experimentally. Consequently, the two serve complementary roles in determining the important mechanisms for a particular process. particular process.Our thermal models do not represent processes in which steam distillation, solution gas, chemical reactions, or compressibility are important. The choice of whether to model physically or to calculate numerically depends on the actual process being studied and the capabilities one has developed in each of these technologies. Scaling rules for steam-injection processes have evolved from those for isothermal and hot-water processes. Isothermal reservoir processes have been processes. Isothermal reservoir processes have been the subject of a number of scaling studies. Scaling for the hot-water drive has been reported in the work of Geertsma et al., Baker, and Dietz; scaling for combustion processes has been given by Binder et al. SPEJ P. 151

scholarly journals Physical modeling applied in evaluation of the safety and efficiency of vessel mooring plans

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Rafael Esferra ◽  
José Carlos de Melo Bernardino ◽  
Paolo Alfredini
Keyword(s):  
Physical Modeling ◽  
Physical Models ◽  
Scale Model ◽  
Small Scale ◽  
Mooring Lines ◽  
Safe Alternative ◽  
Adverse Conditions ◽  
Cargo Handling ◽  
Favorable Conditions

ABSTRACT For cargo handling to be carried out safely and efficiently, port terminals should provide favorable conditions of shelter, thus avoiding excessive movement of moored vessels and mitigating strengths on mooring lines. However, terminals in which the influence of waves, winds or currents provide adverse conditions to keep a vessel moored need to pay attention to the mooring arrangement of the vessels, through studies that guarantee the effectiveness of the system. In this context, small-scale hydraulic physical models are the most accurate tool for simulation of mooring lines plans of vessels, since they can accurately reproduce all the complexity of the hydrodynamics and its interaction with the vessel. This manuscript presents the technique of physical modeling in vessel mooring studies and its application in a case study made for Ponta da Madeira Port Terminal. In a scale model 1:170 was carried out a comparison of two proposed mooring arrangements for the Valemax class bulk carrier, the results of which allowed to define a safe alternative that made the berthing operation feasible during almost 100% of the time.

Constraint Analysis on the Steel Mid Tower of a Tri Tower Suspension Bridge

2010 ◽  
Vol 163-167 ◽  
pp. 79-84
Author(s):  
Qiu Zhao ◽  
Chen Xu
Keyword(s):  
Suspension Bridge ◽  
Horizontal Displacement ◽  
Internal Force ◽  
Spring Stiffness ◽  
Fem Model ◽  
Stability Performance ◽  
The Difference ◽  
The Stability ◽  
Main Girder

A certain project of tri-tower suspension bridge of which the main span was 1080m was taken as a case study of the mid tower stability. A 3D beam FEM model has been carried out to investigate the global mechanical behavior of the bridge in which the internal force response to several different typical load cases were specifically concerned. Moreover, the cable spring stiffness to the mid tower was defined as the ratio of the initial horizontal forces acting on the top end of mid tower to the corresponding horizontal displacement. And the effect of this equivalent spring stiffness on the stability performance of the mid tower was compared to other tow constraint conditions to the tower including free constraint and pin constraint. The comparison showed that the cable equivalent stiffness was 4342kN/m when living load was acting along the whole main girder of the bridge while this value varied with different load cases. The difference between the effect caused by the cable spring stiffness and the free constraint was small indicating that the stability of the mid tower was not sensitive to the cable constraint. In addition, with the increase of the equivalent spring stiffness, the longitudinal buckling eigenvalue also became larger and gradually approached the condition of pin constraint.

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