bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Experimental Technique to Measure Contact Pressure
Authors: Diaconescu Emanuel N. , Glovnea Marilena L. , Petrosel Ovidiu
Published: January 2009

A new technique to measure the pressure in a real contact is proposed. One of contacting surfaces is covered, prior to contact establishment, by a special gel. The contact closing removes the excess gel and, during a certain time interval, the contact pressure transforms the entrapped substance in an amorphous solid. In each point, the refractive index of this solid depends on the pressure acting during transformation. After contact opening, the reflectivity of this coating depends on the former contact pressure and it is mapped by aid of a laser profilometer and becomes an indicator of contact pressure. Theoretical considerations show that the gel must possess certain optical parameters for the method to work. Several experimental reported results offer a clear image upon pressure distribution in Hertz point contacts, end effects in finite length line contacts, pressure distribution between rough surfaces and indicate the onset of plastic deformation.
Nano-Scratching as a Means to Study Wear Debris Generation in Polymers
Authors: Mohamed Sani Rosli Bin , Sinha Sujeet K. , Ying Tan Joyce Pei , Zeng Kai Yang
Published: January 2009

Scratches in the range of 1000 nm deep were produced on the surfaces of two polymers using diamond tip indenter to study the material deformation and wear debris generation characteristics. Our results show that the process of wear debris generation depends upon the manner in which scratches are produced on the surface. Single track scratches do not produce wear debris despite several passes of the indenter tip whereas intersecting scratches accelerate the wear debris generation process. The results indicate that the material near the four corners of intersecting scratches experience extremely high strain leading to extrusion and eventual breakage from the bulk of the polymer forming a debris particle.
A Computational Study of Nano-Scale Contact and Friction
Authors: Streator Jeffrey L. , Kudish Ilya I.
Published: January 2009

A simulation is undertaken to consider the effects of the scale of surface roughness on elastic contact and friction. In the simulation, a cylindrical rigid indenter of a prescribed profile is brought into contact with an elastic half-space. Interaction between the indenter and the half-space occurs through an assumed surface potential derived from the 6-12 Lennard-Jones intermolecular potential. The hypothesis under investigation is that by assuming the frictional stress is proportional to the magnitude of the normal stress, irrespective of sign, one can account for the enhanced frictional stress at the nano-scale vs. the micro-scale that has been observed experimentally. Results of the simulations indicate qualitative agreement with recent experimental findings.
An Assessment of Archard and Persson’s Models for the Elastic Contact of Rough Surfaces
Authors: Ciavarella M. , Demelio G.
Published: January 2009

The Archard and the Persson models for elastic contact of rough surfaces are critically assessed for a Weierstrass series profile, finding that they both do not take into account of redistribution of load and interaction effects fully, unless scales are separated enough.
Study of Transverse Flow Effects on Particle Flows and Contamination of Air Bearing Sliders
Authors: Shen X.-J. , Suk Mike , Bogy David B.
Published: January 2009

For some complex slider designs the two dimensional approximation incorporated in the Reynolds equation for determining the airflow in the air bearing is not applicable due to steps in the air bearing surface. A model that incorporates some transverse flow effects is needed to better characterize the airflow between the slider and disk for some applications. In this paper such a model is derived to better predict the paths of contamination particles entrained in the air bearing. The characteristics of airflow and particle flow within the air bearing are then studied. The analysis including the transverse effects reveals that the transverse velocity of the air is not negligible in the geometric transition regions of the slider. This transverse velocity has a significant effect on the flight path of particles, and therefore, on the particle contamination profile on slider surfaces. The assumption of adhesion of the particles upon impact with a surface is used as the contamination criteria, and it is viewed as the worst-case scenario.
Spreading of Novel Cyclotriphosphazine-Terminated PFPE Films on Carbon Surfaces
Authors: Tagawa Norio , Tateyama Tadao , Mori Atsunobu , Kobayashi Nagayoshi , Fujii Yoshinobu , Ikegami Masako
Published: January 2009

Spreading characteristics of novel cyclotriphosphazine-terminated Perfluoropolyether (PFPE) films on carbon surfaces were investigated experimentally by using a scanning micro-ellipsometer. The apparent diffusion coefficients of novel lubricants were also studied in order to evaluate the spreading speed and they were compared to the conventional Zdol. It was found that the mobility of cyclotriphosphazine-terminated PFPE films is lower than that of Zdol. This characteristics is dependent on the interactions between the end groups of the lubricants and carbon surfaces and it is found that the tendency of “work of adhesion” for the lubricants has a good correlation with the mobility tendency of the lubricants. In addition, the monolayer film thickness of novel lubricant films as well as conventional Zdol was identified, which was extracted using Matano interface method. As a result, the existing conformation of novel cyclotriphosphazine-terminated PFPE film on carbon surfaces could be estimated, based on the monolayer film thickness results.
Electrochemical Tests of Corrosion of Magnetic Hard Disks With Overcoats of DLC
Authors: Jung Soyoung , Devine Thomas M.
Published: January 2009

Two electrochemical techniques were used to investigate the corrosion of DLC coated magnetic hard disks: (1) potentiodynamic and potentiostatic anodic polarization and (2) electrochemical impedance spectroscopy. The objective was to determine the ability of DC polarization and AC polarization to detect the presence of porosity in the DLC. The results indicate that anodic polarization at high potentials (≈ +1.0V vs SCE) to cause pitting corrosion of the metal layers underneath the DLC might provide a rapid and quantitative estimate of the amount of porosity in the DLC. Measurement of the low frequency electrochemical impedance at intermediate potentials (≈ +0.5V vs SCE) appears to indicate the presence of porosity but further work is required to establish a quantitative relationship between the amount of porosity and the value of the low frequency impedance.
Spreading Characteristics of Monolayer Lubricant Film on Surfaces With Lube Textures
Authors: Zhang Hedong , Mitsuya Yasunaga , Fukuoka Natsuko , Fukuzawa Kenji
Published: January 2009

In this paper, from the viewpoint of lubricant spreading, we investigate the effect of lube textures which mean a nonuniform distribution of bonding strength between lubricant molecules and the disk surface. Lube textures were formed by irradiating ultraviolet rays through a stripe-patterned mask onto a magnetic disk surface which was partially coated with one-monolayer film of perfluoropolyether. Surface characteristics of the lube textures were evaluated by surface energies ascertained from contact angle measurements. Spreading of the lubricant film was measured by scanning microellipsometry on the striped lube textures in the directions parallel and perpendicular to the stripes. The thickness-dependent diffusion coefficients extracted from the spreading profiles show that lubricant spreading in the regime of film thickness less than 0.2 nm is faster along the stripes, indicating the possibility of controlling the behavior of a lubricant film with lube textures.
Nanoscale Heat Transfer Modeling in Solids: Data Storage and Electronic Devices
Authors: Ghai Sartaj S. , Jhon Myung S. , Amon Cristina H. , Hsia Yiao-Tee
Published: January 2009

Lattice Boltzmann method (LBM), is used to examine multi-length scale, confined heat conduction phenomena in solids for which sub-continuum regime is important. This paper describes the implementation of the method and its application to cases pertinent to data storage and electronic devices. Thin solid films with internal heat generation and with temperature difference across the boundaries are used as case studies to illustrate the benefits of the LBM. We compare our results with various hierarchical equations of heat transfer such as Fourier, Cattaneo, and Boltzmann transport equations, as well as with experimental and numerical data from the literature. Our results exhibit a good agreement with other methodologies in one and two dimensions, at a much lower computational effort.
Linear Temporal Stability Analysis of a Low-Density Round Gas Jet Injected Into a High-Density Gas
Authors: Lawson Anthony L. , Parthasarathy Ramkumar N.
Published: January 2009

It has been observed in previous experimental studies that round helium jets injected into air display a repetitive structure for a long distance, somewhat similar to the buoyancy-induced flickering observed in diffusion flames. In order to investigate the influence of gravity on the near-injector development of the flow, a linear temporal stability analysis of a round helium jet injected into air was performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The temporal growth rates and the phase velocity of the disturbances were obtained. The temporal growth rates of the disturbances increased as the Froude number was reduced (i.e. gravitational effects increased), indicating the destabilizing role played by gravity.
Effects of Burner Diameter and Fuel Type on Smoke Point and Radiation Characteristics of Diffusion Flames
Authors: Goh S. F. , Kusadomi S. , Gollahalli S. R.
Published: January 2009

The main purpose of this study was to comprehend the effects of burner diameter and fuel type on smoke point characteristics of a hydrocarbon diffusion flame and its radiation emission. The critical mass flow rate of pure fuel at this smoke point was measured. At nine different fractions of the critical mass flow rate, nitrogen gas was supplied along with the fuel to achieve smoke point. At each condition, flame radiation and flame height were measured. The axial radiation profile at the critical fuel mass flow rate for one burner was also measured. Three fuels of differing sooting propensities were used: ethylene (C2H4), propylene (C3H6), and propane (C3H8). Three different burners with inner diameters of 1.2 mm, 3.2 mm and 6.4 mm were used. Results showed that propylene had the highest critical fuel flow rate and the highest nitrogen dilution required to suppress smoking and total flame radiation, followed by ethylene and propane. For all fuels, the curves of nitrogen flow rate required for smoke suppression versus fuel flow rate exhibited a skewed bell shape. The variation of Reynolds number at the critical fuel mass flow rate with the burner diameter showed a linear relation. On the other hand, the variation of total flame radiation with burner diameter was nonlinear.
Unsteady Heat Transfer During the Rapid Compression and Expansion of Air
Authors: Bakhshan Y. , Karim G. A. , Mansouri S. H.
Published: January 2009

The instantaneous unsteady heat transfer during rapid compression and expansion of air within a pneumatically driven piston in a cylinder arrangement which offers simple, well-controlled and known boundary conditions was examined. Values of the instantaneous apparent overall heat flux from the cylinder gas to the wall surfaces were calculated using a thermodynamic analysis of the experimentally measured pressure and volume temporal development. Corresponding heat flux values were also calculated through the application of a zero-dimensional model that incorporates the use of the k–ε turbulence model. Comparison of the results of the model with corresponding experimental data showed fair to good agreement for the wide range of compression ratio values used (8.4∼24.3). Also, correlation of the derived data using an effective velocity which is based on the distribution of mean kinetic energy, turbulence energy and piston motion and a characteristic length that is a function of the instantaneous height between the piston top and the cylinder head and bore diameter as the parameters to use when calculating the Reynolds, Prandtl and Nusselt numbers resulted in the following workable relationship: Nu = 0.01Re0.205 Pr0.033.
Numerical Simulation of Combustion in a Cylindrical Porous Medium
Authors: Mohamad A. A.
Published: January 2009

Convectional free flame combustion causes the temperature rise in the vicinity of the flame to be very steep, resulting in high temperatures, consequently NOx formation enhances. The fact is that the thermal conductivity of gases are very low, i.e., poor thermal conductors. Combustion in porous media elevates this problem by enhancing heat conduction and thermal radiation from the flame zone, which reduces the flame temperature and NOx formation. Also, heat transfer from the free flame to a load is mainly by convection, while heat transfer is by convection and radiation from combustion zone in porous medium to a load. Moreover, it is easy to stabilize the flame in a porous medium, where the thermophysical properties of the porous medium can engineered for specific application. Most of the work is done on flat type porous burner, where the axial flow of gaseous fuel air mixture forces through a layer of porous medium. In this report a concept of cylindrical porous burner is introduced, where the fuel air mixture is forced to flow radially. Mathematical models and simulation results are introduced for both burners, axial and radial flow burners. Preliminary results of the comparison between the thermal performances between the mentioned burners are discussed. The results revealed that the cylindrical burner has superiority over the convectional flat burner. The cylindrical burner has a wide range stability limits and may produce less NOx than the flat type burners.
Ignition and Propagation of Flammable Gas Mixtures in Vessels With Small, Complex Geometries
Authors: Morgan Michael D. , Mehta S. A. , Al-Himyary T. J. , Moore R. G.
Published: January 2009

Anytime flammable gas mixtures are handled, there is a risk of combustion hazard. This is particularly true in many oilfield applications where space is limited and equipment is located near sources of ignition. Unfortunately, there is a lack of understanding of combustion phenomena within process equipment such as mufflers, rotating blowout preventers, liquid traps, and dry gas seal assemblies. These vessels have small internal volumes, complex internal geometries, and are often connected using small diameter piping. This paper discusses the results of a parametric study which was carried out to establish the nature of combustion within small diameter vessels and exhaust tubing. Flowing, pre-mixed fuel/air mixtures were used. This study has been conducted using a testing system capable of emulating real process equipment under realistic field operating conditions, for example, flow rates, back pressures, and fuel type. The results from a representative sample of 79 tests, from the 5,000+ tests that have been completed, are discussed herein. Typical pressure and temperature responses are presented and analysed. In addition, methods of detecting the presence of combustion are discussed. In particular, it is demonstrated that flames can be remotely detected and located using only high speed pressure data.
Oxidation Characteristics of Light Hydrocarbons for Underbalanced Drilling Applications
Authors: Ferguson Helen A. , Mehta S. A. , Moore R. Gordon , Okazawa Nancy E. , Ursenbach Matthew G.
Published: January 2009

This investigation is directly relevant to various applications associated with the safety aspects of underbalanced drilling operations where de-oxygenated air may be co-injected with oil-based drilling fluid. However, de-oxygenated air often still contains up to 5% oxygen by volume. This residual oxygen can react with oil during the drilling process, thereby forming potentially hazardous oxidized hydrocarbons and compromising the safety of drilling operations. This article examines the conditions and processes by which oxidation reactions occur and may be helpful in reducing risk in drilling operations. This project characterizes the oxidation behaviour of several oils and a typical oil-based drilling fluid at atmospheric and elevated pressures using thermogravimetry (TG) and pressurized differential scanning calorimetry (PDSC). Tests performed on mineral matrix (core) from the oil reservoirs showed no reactivity in both inert and oxidizing atmospheres. In an inert atmosphere, tests on all hydrocarbon samples showed only vapourization, no reactivity. In an oxidizing environment, the tests on hydrocarbons showed several oxidation regions. The presence of core had no effect on the behaviour of the hydrocarbons tested in an inert atmosphere but accelerated the higher temperature oxidation reactions of the oil samples. The oil-based drilling fluid exhibited the opposite effect — the presence of core material retarded the oxidation reactions. This is perhaps due to the presence of an oxygen scavenger reacting with oxygen containing clays present in the mineral matrix. In all tests performed on mixtures of hydrocarbon and core in oxidizing atmospheres, elevated pressures resulted in acceleration of the lower and higher temperature reaction regions.
A Neural Network Based Predictive Emission Monitoring Model for NOx Emission From a Gas Turbine Combustor
Authors: Kibrya G. , Botros K. K.
Published: January 2009

A Predictive Emission Monitoring (PEM) model for predicting NOx emission from a gas turbine combustor has been developed by employing an optimized Neural Network (NN) architecture. The Neural Network was trained by using actual field test data and predicted results of a Computational Fluid Dynamics (CFD) model of the combustor. The field tests were performed at a natural gas compressor station driven by a General Electric (GE) LM1600 conventional gas turbine. The model takes eight fundamental parameters (operating and ambient) as input, and predicts NO and NOx as outputs. The data used for training the model covers the entire operating ranges of power and ambient temperature for the site. The CFD model employs a non-equilibrium (flamelet) combustion scheme and a set of 8 reactions including the Zeldovich mechanism for thermal NOx, and an empirical correlation for prompt NOx formation. The results predicted by the CFD model were within 15% of the measured values. Results of the field tests demonstrated that the spool speed ratio of the gas turbine remained constant throughout the tests, the power output of the engine was linearly proportional to the spool speeds, and the NOx emission was proportional to the site power output. A Multi Layer Perceptron type Neural Network with two hidden layers, each with four neurons was found to be the optimum architecture for the model. The NO levels predicted by the PEM model based on the optimized NN had a maximum absolute error of approximately 7%, mean absolute error of 2.3% and standard deviation of 1.97%. One year operating data for the site was submitted to the trained NN model with ambient temperatures varying from −29.9 °C to 35.7 °C and output powers from 5.8 MW to 17 MW. It was found that the model produced consistent contours of NO emissions. As expected, the NO levels were found to increase with increasing power and/or ambient temperature.
The Effect of Solid Surface Roughness on Dynamic Contact Angles in Solid-Liquid-Liquid Systems
Authors: Rao Dandina N. , Radwani Hussain H.
Published: January 2009

The engineering applications of spreading and adhesion phenomena involving fluids on solids are numerous. The adhesive and spreading interactions at the solid-fluid interfaces are well characterized by dynamic contact angles. This study reports on the results of an experimental investigation into the effect of solid surface roughness on dynamic contact angles in solid-liquid-liquid (S-L-L) systems. The experiment involved the use of Wilhelmy Plate apparatus to measure adhesion tension (which is the product of interfacial tension and cosine of the contact angle between the liquid-liquid interface and the solid surface), the DuNuoy tensiometer to measure the liquid-liquid interfacial tension, and a profilometer to characterize the roughness of the solid surfaces used. The components of the solid-liquid-liquid systems studied consisted of: (i) smooth glass, roughened quartz and an actual rock surface for the solid phase, (ii) normal-hexane and deionized water as the two immiscible liquid phases. The dynamic contact angles (advancing and receding angles) of the three-phase (rock-oil-water) system provide essential information about the wettability of petroleum resrvoirs. The wettability of a reservoir is an important parameter that affects oil recovery in primary, secondary, and enhanced recovery operations [1]. Contact angle measurements on smooth surfaces are generally used to characterize reservoir wettability. However pore surfaces within reservoir rocks are essentially rough and hence it is important to determine the effect of such roughness on measured contact angles. There is very little information in the open literature on the effect of surface roughness on dynamic contact angles in S-L-L systems. In the present work, four levels of roughness of solid surfaces of similar mineralogy (quartz and glass) were tested in hexane-deionized water fluid pair. The advancing and receding contact angles measured at ambient conditions were analyzed for wettability effects. It was found that as surface roughness increased, the dynamic contact angles also increased. The wettability of the rock-oil-water system shifted from weakly water-wet for the smooth glass to intermediate-wet for the roughened surface. The general trends observed in our study were found to be in good agreement with other published results. However, the generally held notion of increasing contact angle hysteresis with increasing roughness appears to be incorrect in solid-liquid-liquid systems.
Buckling Analysis of a Taper-Taper Adhesive-Bonded Composite Joint
Authors: Helms Jack E. , Li Guoqiang , Pang Su-Seng
Published: January 2009

An analytical model of the behavior of an adhesive-bonded taper-taper composite joint under axial compressive loading has been developed using the Ritz Method. The model was based on laminated beam theory. A Fourier series was used to represent the transverse displacement variable and the Ritz method was used to derive an eigenvalue equation for adhesively bonded taper-taper composite joint. The smallest eigenvalue is the critical buckling load. Finite element analyses were performed on two unidirectional laminated beam joints with various taper angles to verify the analytical model. The effect of varying the taper angle, adhesive thickness and adhesive modulus on the critical buckling load were investigated analytically.
Numerical Study on Shock Wave Profiles in 6061-T6 Aluminum Using Shock Viscous Stresses
Authors: Abe Akihisa
Published: January 2009

In order to accurately predict particle velocity profiles of steady shock wave fronts propagating in solid materials, a new numerical calculation method was proposed. The present method was based on one-dimensional Lagrangian finite difference wave code, and shock viscous stresses evaluated theoretically were introduced into the present numerical code. The shock viscous stress that is one of the important parameters to shape the rising profile of the shock wave front was calculated by the inside temperature estimate method for the steady shock wave fronts. The present calculation method was applied to the uniaxial strain problem of 6061-T6 aluminum at some stress levels below 8.86 GPa, where the elastic and plastic steady shock waves will appear. The results of the present calculation could reproduce more accurately the experimental data measured by the velocity interferometer system (VISAR). In addition, the present calculation was applied to a shock stress level of 20 GPa to investigate the shock viscous effects in the overdriven shock wave rising profile.
Ontology-Based Automatic Classifier for Classifying the Web Pages
Authors: Prabowo Rudy , Jackson Mike , Burden Peter , Kno¨ll Heinz-Dieter
Published: January 2009

This paper presents an ongoing project which enhances the design and implementation of the automatic classifier for classifying the Web pages, known as Automatic Classification Engine (ACE). The enhancement focuses on the use of the ontologies of the domains to carry out classification. To articulate the underlying theories of an ontology, the meaning of a concept, a terminology and a gestalt instance is elucidated. The enhancement results in better classification in terms of accuracy.
Environmental Responsibility: A Panacea for Operational Disturbances
Authors: Adebayo Ifebajo J. , Ibizugbe O.
Published: January 2009

Reports from onshore E & P activities in Nigeria have shown that operating in the Niger Delta region poses some of the toughest challenges in the world. This region has witnessed a spate of attacks on oil and gas facilities, staff and contractors. Consequently, major oil and gas players have to contend with complex operational uncertainties due to increase pressure from the local communities for improved environmental control measures. To effectively de-risk this region of this category of operational uncertainties, the industry must begin to see environmental performance as not only a measure of how well she can comply with existing environmental regulations, but also as a measure of how well she can pre-empt environmental pressures as well as maintain constant harmony with all concerned stakeholders and seeing herself as responsible to the environment with a view to improve performance. In this project, we have been able to develop SMART* models based on continuous consultation, integrated management approach and continuos improvement attitude (CIA). With a good FOCUS* approach, this will help in safe and effective operations, pre-empt pressures, maintain harmony with local communities and effectively manage operational disturbances within complex environmental settings like the Nigerian Niger Delta area. Finally, we are of the opinion that every industry that seeks to remain efficient and relevant in this millennium should constantly be looking for ways of becoming more environmentally responsible — because no business can call itself efficient if it threatens the environment within which it operates. • SMART is an acronym for Specific, Measurable, Achievable, Realistic and Time Bond. • FOCUS is an acronym for Fair, Objective, Consistent, Unbiased and Succinct.
Environmental Protection Management in INA
Authors: Svel-Cerovecki Svea
Published: January 2009

INA-Industrija nafte d.d., is one of the largest companies in the Republic of Croatia. Its principal activities are oil and gas exploration and exploitation, oil refining and processing, oil and gas transportation and sale of fuels and associated products. Such a type and scope of activities requires a major responsibility and a systematic approach to planning, implementing and monitoring the environmental protection. In 1998 INA management adopted so called “green” documents for the purpose of improving the environmental protection activities: “Decision on establishing an integral environment management system” and “Environmental protection policy declaration”. The system implementation activities are under way and four organizational units of INA have obtained ISO 14001 certificate for the successfully implemented environment management system. This paper provides an insight into INA’s environment impacts as well as information about the performed environmental protection management activities and achievement of sustainable development. The attention is drawn to the way company’s units carry out their activities to comply with the current environmental legislation. The information is also provided on INA’s way to participate in national eco-projects and cooperation with international institutions in order to achieve eco-efficiency. Following the requirements according ISO 14001, as well as by major investments, INA contributes to the environmental improvement on local, regional and global levels.
Environmental Control Technologies in Drilling and Production Operations Within Austrian Oilfields
Authors: Bacher Reinhard , Ruthammer Gerhard
Published: January 2009

It has to be the vision of an international oil and gas exploration and production company to explore for and produce oil and gas in the most economically efficient, social responsible and environmentally acceptable way. Based on this aim and due to the fact that Austria is a country with a environmental awareness and a high tourism level, OMV as the leading domestic oil and gas company had to elaborate strategies for the benefit of the company, its employees and shareholders, but also for the benefit of local communities maintaining the image of a healthy, clean and relaxing environment. The paper describes the different ways of implementing environmentally relevant technique and strategies beginning with exploration process and ending with the monitoring of oilfield wastes. Case histories demonstrate the concept of converting onshore drilling projects into action in environmentally sensitive regions using the idea of “ecological compensation”. Further a new technology of water treatment based on “microbiological clarification” is shown. With the new water treatment technology a valuable contribution to the protection of environment could be shared by OMV, because this method works without any application of biocides. Finally, innovative methods of calculating the risk potential of oilfield deposits using micro-geophysical surveys are illustrated. This measuring practice takes care of the electric resistivity contrast between oilfield deposits to its surrounding, so that any leakage can be observed immediately due to the change of electric resistivity profile. Generally the paper has the goal to illustrate acceptable ways to meet the environmental sensitivities of communities and authorities.
Environmental Impact of Over-Regulation
Authors: Hargis Dean
Published: January 2009

Consideration of a global viewpoint in modern impact analyses suggests that we should favor the efficient use of available infrastructure over the wasteful development of new infrastructure when comparable volumes of oil and gas production are concerned. This global benefit of efficient development is overlooked in traditional environmental impact analyses that typically focus on local concerns within a narrow geographic range. This traditional approach, which is common in more affluent developed countries, may actually contribute to increased global impacts by establishing stringent regulatory regimes discouraging development that would allow the efficient long-term use of that infrastructure. This disregard for global efficiencies favors development in underdeveloped countries where economic development goals may overshadow local concerns for environmental protection. This paper is based upon the results of a study of onshore industrial infrastructure capacity in Central California sponsored by the U.S. Minerals Management Service. This study evaluates the oil and gas production potential of offshore leases that could be accommodated by existing infrastructure and a balanced program of facility replacement. Though these oil and gas resources were originally identified over ten years ago, local environmental policies have delayed their development. An example of oil and gas production activities in other parts of the world that provide energy supplies equivalent to this unrealized potential is described along with an overview of selected environmental characteristics. This paper concludes that environmental review procedures addressing oil and gas development should include consideration of global implications of locally restrictive approval policies.
Decommissioning Offshore Production Facilities
Authors: Ruivo Fabio M. , Morooka Celso K.
Published: January 2009

Decommissioning offshore oil and gas production facilities have been progressively increasing the concern of the industry, government and other interest groups through the last years. There are at least two reasons for this sudden regard. First, it is the maturing of several oil and gas fields around the world in recent years. Second, it is the growing impact of environmental concerns in international affairs. Despite several works published address to some techniques and to potential problems and risks related to decommissioning offshore oil and gas production installations its procedures are in some extent an innovative issue, especially in Brazil. Therefore, the motivation of this paper is the novelty of the subject in Brazil, since the national industry is just beginning to deal with the end-of-leasing obligations, which involve decommissioning operations. The main ambition is to stimulate debate about appropriate issues.
Calculating Benzene Concentration Emitted During Tanker Loading
Authors: Majima Takahiro , Yamanouchi Hiroshi , Yamaguchi Katsuji
Published: January 2009

Benzene emissions occur during operations. These emissions are regulated in several counties. Accordingly, we developed one-dimensional benzene diffusion model advancing in the vertical direction. Unlike other models, the instant model is based on a 1/10 scale modeling of eddy diffusion at the liquid surface during initial loading operations and advection under tank roof during final loading operations. The model input parameters include loading rate, flow rate, cargo tank size, and temperature dependent saturated concentrations. The validity of the model is demonstrated by comparisons with onboard measurements. Other models exist. However, they are based on empirical estimate rather than rational modeling.
Decommissioning of Offshore Installations — Experience Related to Safety and Environment and the Philosopy: “How Clean is Clean Enough?”
Authors: Bjerkelund Mina Hynne
Published: January 2009

This paper will give a brief presentation of experience gained over the last 5–10 years of decommissioning of offshore installations in the North Sea. Focus is given to safety and environment issues, as this is the driven factor towards decommissioning and deconstruction of offshore installations. The establishment of cleaning criteria is based on experience from The Ekofisk I Field where a number of installations should be out of production and shut down prior to final disposal. The disposal solution was not yet defined; therefore a “cold phase” was defined. The installations would stay in place for an unknown period of time. Cleaning of large storage tanks, such as Brent Spar, Maureen Alpha and The Doris Tank is a challenge due to the size and layout of the tanks and the content, such as H2S, wax, scale, sediments, etc. Special cleaning techniques and methods are developed for each tank. Reuse of installation or part of the installation is a target. Re use of the installations to what they were originally designed for, has been a main issue, but not yet succeeded. In the North Sea, no installations so far have been re used. Lot of effort is put into risk management and waste management. Risk related to deconstruction work, both onshore and offshore, is a major concern. All statistics demonstrates challenges towards work performance in deconstruction projects. It is important for the offshore industry to maintain a good reputation and to be a reliable and orderly partner for safety and environmental aspects of the industry.
The Role of Well Testing in Recognizing Deferred Production Revenue
Authors: Mehdizadeh P. , Perry D. T.
Published: January 2009

Well testing is routinely performed to evaluate the performance of a well, which establishes the allocation factor for the lease, which in turn establishes tax and royalty basis. Most well testing is done with conventional gravity separators, which separates the produced stream into oil, water, and gas components and measures these individual components as individual streams. New multiphase measurement technology improves well test results through improved accuracy, consistency, and more frequent well testing. This paper examines the implication of these improved capabilities to recognize well problems and optimize production. A simple economic model is provided that an operator can use to assess the balance between the cost of performing periodic well tests and the benefits of more quickly discovering well problems that can result in less than expected production. The model relates the cost of decreased production, as the result of unforeseen changes in the well, to the frequency and accuracy of the well tests. The model derives an optimum test interval that minimizes the total cost of well testing and deferred production on the basis of the probability that a higher than normal decline in production rate can be detected by well testing. The model is then used in several field examples to assess the optimum period between well tests and how the optimum period can lead to reduced cost of operation and improved production.
Test Facility for Multiphase Flow Problems
Authors: Britton Charles L.
Published: January 2009

A physical description and the operating characteristics for a multiphase flow test facility are given. The facility is designed for wet-gas conditions where the gas-void-fraction (GVF) is typically greater than 0.95. However under many conditions, the liquid flowrate can be increased which results in a lower GVF. Lean natural gas, whose typical energy content is less than 1100 BTU/ft3, is used as the flowing gaseous media. The flowing liquid can range from a pure hydrocarbon liquid (such as decane) to a mixture of water and hydrocarbon liquids (condensate). Several investigations into the performance of various single-phase flowmeters and gas-liquid separators have been conducted for wet-gas flowing conditions. Present work includes the modification of the test facility to study hydrate formation and methods that can be employed to inhibit the hydrate formation. Visual images obtained with a high-pressure viewing section will be presented which show the different flow patterns that can exist within pipes that are contain multiphase fluids.
New Micromechanics Formulations for the Assessment of Elastic Moduli of Granular Assemblies
Authors: Wang Linbing , Macari Emir , Woldesenbet Eyassu
Published: January 2009

The elastic moduli of granular assemblies are sensitive to the confining conditions as well as the volume fractions of each of its constituents (i.e. solid, fluid, gas). Theoretical estimations using granular mechanics are based on assumed distributions of contact normals and branch vectors using idealized particle shapes and therefore cannot quantitatively predict the moduli. This paper presents a new method to use the moduli of the granular skeleton and those of the matrix to estimate the moduli of the composite and makes it possible to back-calculate the moduli of the skeleton from the moduli of the composite and the matrix.
Sensors in Virtual Reality Experiments
Authors: Guo Wei , Jana Amitava , Mensah Patrick F. , Ibekwe Samuel , Dunn Mariea C.
Published: January 2009

Virutal reality is emerging as an important tool for training and entertainment by creating an environment in a computer that allows a user to interact with objects perceived as real. The cost of providing such a virtual reality interfaces is often prohibitive thereby making it unavailable to many institutions for their research, training, and students’ projects. Critical components of this system have been identified as sensors, electronic interfaces and software. This paper explores different sensors available to make a low-cost virtual reality project possible. Using cheaper available quality components, the authors are in the process of developing a low cost cyber glove for education and training. Availability of such a system will also open doors for training for oil industry workers, etc. especially in hostile or dangerous environments without being physically exposed to such hazards.
Finite Element Analysis of Composite-Concrete Adhesion
Authors: Woldesenbet Eyassu , Hailu Haftay
Published: January 2009

The need for the rehabilitation of bridges and structures is becoming more apparent as the number of deficient civil structure grows and the cost of replacement is becoming prohibitive. These leads to the search of alternative methods, such as rehabilitation, to put the deteriorated structures back to normal operation with the least possible cost. One such method is the use of composite plates adhesively bonded to concrete as reinforcement and to prevent the propagation of crack within the concrete structure. In this study the load transfer and the resulting stress distribution in the composite-concrete adhesion system is investigated using the finite element method. The effects of the different bond parameters are studied using the finite element. In addition, results of the finite element analysis are proved to be in agreement with the analytical solution of shear stress distribution in the adhesion layer that was developed in previous studies by the authors.
A Fuzzy Logic Control Model for the Curing Process of Heat-Activated Coupling of FRP Composites to Alloy Pipes
Authors: Soysal Omer M. , Mensah Patrick F. , Jana Amitava
Published: January 2009

A fuzzy control (FLC) approach has been developed to control the curing process of a polymeric laminate used as the bonding material for the heat-activated coupling (HAC) of a fiberglass composite to Cu-Ni alloy pipe. Controlling the temperature of the curing environment is required in order to achieve uniform cure within the bonding prepreg. Without temperature control, the alloy side of the coupling is essentially a heat sink. Therefore, a controlled heat source on the alloy pipe is needed to compensate for the heat sink effect that tends to decrease curing temperatures within the laminate. The simulation results obtained show that the curing process of HAC of a composite-to-alloy pipe is significantly improved with required uniform cure characteristics being obtained through the thickness of the laminate.
Rheological Analysis of Curing Process of Epoxy Prepreg Used as Composite Pipe Joints
Authors: Sun Liangfeng , Sterling Arthur M. , Pang Su-Seng , Stubblefield Michael A.
Published: January 2009

The rheological properties of curing process of epoxy prepreg were measured by Bohlin Rheometer. The variations of storage modulus, loss modulus and viscosity are monitored vs. the cure time and temperature. Viscosity profiles were described by different models. Except the first order viscosity models, new viscosity models based on Boltzmann function were proposed. In the new models, a parameter called critical time was introduced. Critical time is a function of temperature and also meets an Arrhenius law. The activation energy calculated by critical time closes to that obtained by initial viscosity. The kinetic rate constants in the old and new models are comparable at each temperature, and the kinetic activation energies calculated from rate constants in the old and new models are very close. The fitting results show that the proposed new viscosity models are better than the old models for both isothermal and dynamic cure processes.
Shell and Tube Heat Exchanger Reliability Study
Authors: Gamio Carlos , Pinto F. Walter
Published: January 2009

In 1997, heat exchanger tube failures accounted for 31% of the unplanned downtime in the Lyondell’s Gulf Coast plants. This resulted in over $12MM of unplanned production interruptions. A multi-disciplinary team studied the tube failure modes and developed a systematic program to improve the heat exchanger reliability. The team issued recommendations in the areas of heat exchanger design, construction, operation, maintenance and inspection. This paper mainly discusses the three critical areas surrounding the reliability of heat exchanger tubes. They are tube testing, strategy on retubing exchangers during turnarounds and design improvements.
On the Burst of Pipes Under Internal Pressure and Elevated Temperature: Part 1 — Rate Independent Study
Authors: Sun Maoye , Bunch Paul
Published: January 2009

This paper presents the results of a study on how the burst of steel tubes is influenced by elevated temperature between 75°F and 350°F (24°C and 177°C). The study involves experiments and modeling of burst. Burst tests were conducted on UNS S32750 super duplex stainless steel. Part I is concerned with rate independent burst, while part II (to be published) is concerned with rate dependent burst. Two models were used to simulate the burst experiments. In the first model, the tube is represented as a cylindrical expansion membrane. In the second model, the tube is modeled as a finitely deforming shell which allows a bulge to grow in the unsymmetric manner seen in the final stages of the experiments. Both models produce the burst pressure accurately. The second model has the advantage of being able to study the effect of local thickness imperfections.
Numerical Performance Prediction and Experimental Validation of an Axial Pump Under Two-Phase Flow (Liquid/Gas)
Authors: Tremante Andre´s , Moreno Nathaly , Rey Robert , Noguera Ricardo
Published: January 2009

The main goal of the present work is to establish the tools of the analysis and performance prediction of an axial pump stage under two-phase flow presence of liquid and gas. This knowledge is very important for different applications, for example in the oil industry. The transport of two-phase flow (oil and gas) that comes from the well implies the utilization of separation and treatment facilities before they are pumping. It means that a lot of economical resources are involved in this kind of industrial operation. Therefore, depending on the function optimization of this type of two-phase pumps, it would permit the substitution of the traditional expensive facilities in addition with energy cost savings. In order to predict the fluid dynamics characteristics of an axial pump stage under two-phase flow conditions and in view to improve its performance, the present research will describe a multi-fluid model in order to solve the momentum equations (Navier-Stokes) coupled with the continuity equation. Here, we will take into account the viscosity of the liquid phase and the compressibility of the gas phase, using the CFD simulator: CFX 4.0. Finally, an experimental facility was designed and built to test one axial pump of two stages. Therefore, experimental data is shown in order to validate the previous numerical results obtained.