bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infinite-Acting Physically Representative Networks for Capillarity-Controlled Displacements
Authors: Behseresht Javad , Bryant Steven L. , Sepehrnoori Kamy 
Published: July 2009

Summary
Drainage/imbibition simulations are traditionally performed on finite regular lattices. If physically representative networks are used instead, the spatial correlation of pore space features inherent in granular materials is automatically accounted for. However, even these networks are obtained from finite samples, and conditions must be specified on the boundaries. Making the conditions correspond to physically realistic situations is difficult, especially for simulations of phase trapping. This paper presents a method of constructing infinite-acting model rocks, in which a well-defined criterion for phase trapping is possible that is independent of boundary conditions. The foundation of the model is computergenerated dense random periodic packings of spheres. We illustrate the method with simulations of drainage and irreducible wetting-phase saturations. To eliminate possible confounding effects from grains being arranged differently, we compare simulations in infinite-acting networks with simulations in the finite network taken from the unit cell of the periodic packing. Wetting-phase connectivity is assessed globally and accounts for all phase morphologies, including pendular rings.
The drainage endpoint for a finite network was highly sensitive to the number and location of the exit pores; while using the infinite-acting network, we removed this latter sensitivity. Comparison with experiments showed that a strict criterion of wetting-phase connectivity (pores connected only by throats filled with wetting phase) cannot account for typical values of Sw,irr and that connectivity must persist via pendular rings.
Typical laboratory experiments and simulations in finite networks yield drainage curves that approach irreducible wetting phase saturation Sw,irr gradually, with large changes in capillary pressure inducing only small changes in saturation. Simulations in infinite-acting networks do not exhibit this behavior. We argue that these simulations are more representative of behavior in the field and that typical laboratory measurements underestimate the value of Sw,irr.
Experimental Study of CO2 Injection Into Saline Formations
Authors: Cinar Y. , Riaz A. , Tchelepi H. A. 
Published: July 2009

Summary
We present laboratory experiments to investigate the influence of gravitational, viscous, and capillary effects on the CO2 injection process. Quasi 2D experiments are performed in a vertical glass-bead pack in the parameter range of interest for CO2 sequestration in deep aquifers (i.e., with Bond numbers of approximately 10−3 and capillary numbers on the order of 10−4). The objective is to investigate the type of flow regimes that occur under favorable as well as unfavorable conditions of density and viscosity. The experiments demonstrate the existence of pore-scale instability in the presence of unfavorable gradients of viscosity and density. Consequently, conventional mathematical models may not be able to represent these unstable flows appropriately. A comparison with estimates from percolation theory shows reasonably good agreement with experimental observations.
A Novel Hydraulic Fracturing Model Fully Coupled With Geomechanics and Reservoir Simulation
Authors: Ji Lujun , Settari A. , Sullivan R. B. 
Published: July 2009

Summary
Unconventional fracturing techniques, such as high-rate waterfracs, waterflooding, or steam stimulation, produced water and cuttings reinjection, CO2 sequestration, and coalbed methane stimulation, are difficult to model because of strong interactions among the fracturing process, geomechanical changes in the porous media, and reservoir fluid flow. The resulting strong poroelastic/thermoelastic effects, permeability and porosity changes, and possible rock failure make current conventional fracturing models inadequate in such circumstances. Therefore, it is necessary to develop new models that include all of these mechanisms and that are capable of conducting integrated data analysis.
This paper presents a new fracturing model with all of these mechanisms included. The model fully couples fracture mechanics with reservoir and geomechanics simulation. This methodology allows us to model fracture initiation and propagation, post-frac multiphase cleanup in the reservoir and fracture and pre-frac and post-frac well performance in a changing stress and pressure environment, all within the same system.
The model couples a 3D finite element geomechanics model with a conventional 3D finite difference reservoir flow simulator. The geomechanics module implicitly models fracture propagation via displacements on the fracture face. The flow and geomechanics/fracturing are coupled in an iterative manner that is equivalent to full coupling of geomechanical and reservoir flow modeling. The 3D (planar) fracture geometry and the pressures in it are the common dynamic boundary conditions for the flow and stress modules. The new iterative process yields smooth fracture propagation, and the model has been tested on classical fracturing problems.
A field example demonstrates the validity and advantages of the approach. To illustrate the model capabilities, we model a waterfrac stimulation performed in Bossier tight-gas sands. The model results show that the model is capable of matching complex injection history and calibrating the stress-dependency of formation permeability.
Effect of Droplet Size on the Reaction Kinetics of Emulsified Acid With Calcite
Authors: Al-Mutairi S. H. , Nasr-El-Din H. A. , Hill A. D. , Al-Aamri A. D. 
Published: July 2009

Summary
Unlike other acid systems, such as gelled and viscoelastic surfactant-based (VES) acids, where the mobility of hydrogen ion controls the overall rate of the reaction, emulsified acid/calcite reaction involves the transport of acid droplets in the diesel phase to the rock surface, breaking of acid droplets, and then the actual reaction on the surface. A limited number of papers have been published on the reaction kinetics of emulsified acid. However, none of the published work considered the effect of acid droplet size on the reaction of emulsified acid. The objective of this work is to examine the effect of the acid droplet size on the reaction rate of emulsified acid with calcite.
The acid was 15 wt% HCl emulsified in diesel with 70:30 acid/ diesel volume ratio. The emulsifier concentration was varied from 1 to 10 gpt. All emulsions were characterized by measuring the droplet size distribution, viscosity, and thermal stability. Diffusivi-ties were measured using the rotating disk device. The experiments were carried out at 25, 50, and 85°C, under 1,000 psi pressure, and disk rotational speeds from 100 to 1,000 rev/min. Samples of the reacting acid were collected and analyzed to measure calcium concentration in the reactor.
The effect of the acid droplet size on the overall reaction rate was significant. The diffusion rate of acid droplets to the surface of the disk was found to decrease with increasing emulsifier concentration because of higher viscosities and smaller droplet sizes. The effective diffusion coefficient of emulsified acid was found to increase linearly with the average droplet size. Emulsions with low emulsifier concentrations (1 gpt) had average droplet sizes of nearly 13 μm. These emulsions were found to have high effective diffusion coefficients (5.093 × 10-9 cm2/s) and low retardation. On the other hand, emulsions with high emulsifier concentrations (10 gpt) had smaller average droplet sizes (nearly 6 μm) and found to have low effective diffusion coefficients (4.905 × 10-11 cm2/s) and high retardations.
The new sets of data can be used to determine the optimum emulsified acid formulation to yield deeper acid penetration in the formation. It is suggested that droplet size can be adjusted to produce the desired diffusion coefficients for acid fracturing treatments.
Completion Analysis and Tracer-Derived Proppant Distribution Improve Completions in the Piceance Basin
Authors: Balderston M. A. , Stabenau J. D. , Holcomb D. L. 
Published: July 2009

Abstract
In June 1996, a two-phase project was initiated to determine how multiple zones react to fracture-stimulation treatments in the Mesa Verde formation, which is located in the Piceance Basin of the western Rocky Mountain Region in the U.S. On the basis of the collected information, study participants evaluated and redesigned procedures to increase the operator's profitability. Limited-entry fracturing was used as the primary fracturing technique, and a multiple-isotope, spectral gamma ray imaging tool was used for evaluating early, middle, and late proppant distribution with three isotopes. During the two-phase project, 20 wells and 218 sands were perforated and targeted for stimulation.
Cleaning Wells from Unexpected, Contaminated Polymer Mud: A State-of-the-Art; Case History
Authors: Talabani Soran , Al Jaberi Salem , Efnik Mohamad S. 
Published: July 2009

Abstract
The presence of the remaining, non-damaged drilling fluid in the well bore before completion might lead to a complicated situation. Furthermore, the non-damaged fluid may generate a kind of sticky material when it interacts with Calcium or potassium ions present in the formation water, hydrogen sulfide, and hydrochloric acid during acid job.
The sticky material found in some wells was spongy and restricted the oil flow rate. None of the production logging tools was able to record data in the presence of this material.
It is believed that a chemical interaction took place between a modified polymer present in the drilling fluid with some higher rank ions than sodium. This interaction releases the trapped water and results in polymer molecules that are polarized with some oil molecules in the presence of a very low pH solution such as a continuous phase (acid). This resulted in a sticky material that could not penetrate the formation but restricted the flow rate.
In this paper the possible reasons for the creation of this material and their chemistry are addressed, the presence of the materials that caused it, and possible solutions that dissolve this material without altering the pay zone rock properties.
Case history from one field shows that in order to avoid the creation of this sticky material, horizontal wells should be totally cleaned and displaced by water before any acid job application.
The chemical that is used to dissolve this sticky material is environmentally safe, causes no damage to the formation pay zone and is economic to use.
The Use of Real-Time Automation to Further Production System Optimization in the Oil Industry
Authors: Cramer Ron , Dunham Cleon , Al Hinai Alley 
Published: July 2009

Abstract
The oil industry is a mature user of SCADA systems, moving from basic monitoring and control into utilizing real time data to optimize the process. Optimization capabilities are improving the economics of oil and gas production operations facilitating production of low cost oil.
The paper outlines the components of "production system optimization" currently being implemented with special emphasis on real time capabilities. Specific examples from Oman are included to show how the technology is improving the life-cycle economics.
A Gas Field Automation System for Enhancing Production and Well Safety
Authors: Reyes Alfonso , Plunkett Joe , Teja Ricardo , Zambrano Oscar 
Published: July 2009

Abstract
The automation of the high-production Ramos gas field, located in the northern region of Argentina, has enhanced field production and well safety and has improved operations by centralizing control of the gas production. A field supervisory control and data acquisition (SCADA) computer located in the gas treatment plant automates the gas production throughout the field by means of a radio telemetry link to a well control unit (WCU) located at each automated well site. Operations personnel can monitor production variables from the plant at any site, view real-time or historical trends of those variables, or change setpoints in a WCU from graphical screens on the computer console. In addition, the production data is archived to a hard disk for further processing and analysis.
Currently, the automation system involves six wells. Five additional wells will be automated during 1999. A solar-powered WCU located at each site controls well production by means of an electrically activated choke. This microprocessor-based controller monitors operating pressures, temperatures and tank levels, and it ensures well and flow-line safety by controlling the operation of the surface safety valve (SSV) and the sub-surface safety valve (SSSV).
Proactive Risk-Assessment-Based Management
Authors: Gruver Steve 
Published: July 2009

Abstract
Traditional management techniques tend to address events in a reactive manner. Many of the documents that are produced in managing day-to-day activities, including morning reports and safety statistics, cover events that have already taken place. With this information in hand, management takes steps to minimise the effects of the action that has taken place and makes further plans to prevent a reoccurrence. This can lead to a cycle in which there is insufficient time to pro-actively plan and look ahead due to the amount of time required to react to events that have already happened. With this in mind, a trial was conducted using an active pro-active risk-assessment based management technique with positive results in accident statistics, personnel turnover and unplanned events.
The Success of Steerable Ream While Drilling Technology Applied in Valhall Field-Norway
Authors: Kinn Sigurd , Marshall Gai-Lynn E. , Poerschke Wilfried , Christensen Hughes , Froehlich Norbert 
Published: July 2009

Abstract
As part of a major oil company's objective to save rig time as well as reduce open-hole exposure time in the Valhall overburden, steerable ream while drilling technology was utilized in their deviated and horizontal wells to eliminate under-reaming thus reducing drilling costs.
The well paths require good directional control with holding capability while drilling long tangent sections. Since a single assembly is designed, the rotary steerable assembly must be capable of programmable dog leg generation when changing inclination and direction or geosteering in the horizontal section.
This paper describes the application of steerable ream while drilling in different hole sections on several wells. Case studies will be presented from wells drilled from the Valhall platform by a jack up rig cantilevered over the wellhead platform. The authors will outline the reasons for utilizing SRWD's and the operational achievements of the system while drilling well F-8, particularly in the two largest hole sections where the tool saved 10-12 days of rig time.
The problems observed while drilling directional and horizontal well paths with steerable motor assemblies will be presented in addition to the modifications implemented as solutions. These improvements should make it possible to further improve ROP and steering abilities on future wells. Additionally, the authors will discuss the improvements achieved by applying new cutter technology and design changes for stabilization of the pilot bit.
Deep-Bed Filtration Under Multiple Particle-Capture Mechanisms
Authors: Guedes R. G. , Al-Abduwani F. , Bedrikovetsky P. , Currie P. K. 
Published: July 2009

Summary
Severe injectivity decline during seawater injection and produced-water reinjection is a serious problem in offshore waterflood projects. The permeability impairment occurs because of the capture of particles from injected water by the rock, both internally in the pores and externally in a filter cake. The reliable modeling-based prediction of injectivity decline is important for injected-water-treatment design and management (injection of seawater or produced water, water filtering, etc.).
The classical deep-bed filtration model includes a single overall description of particle capture. During laboratory or field data interpretation using this model, it is usually assumed that several simultaneously occurring capture mechanisms are represented in the model by a single overall mechanism. The filtration coefficient, obtained by fitting the model to the laboratory or field data, represents the total kinetics of the particle capture. The purpose of this study is to justify this approach of using an aggregated single filtration coefficient.
A multiple-retention deep-bed filtration model needs to describe several simultaneous capture mechanisms. The kinetics of the different capture mechanisms can differ from one another by several orders of magnitude. This greatly affects the particle propagation in natural reservoirs and the resulting formation damage. In this study, a model for deep-bed filtration taking into account multiple particle-retention mechanisms is discussed. It is proven that the multicapture model can be reduced to a single-capture-mechanism deep-bed filtration model. The method for determination of the capture kinetics for all individual capture processes from the breakthrough curve is discussed. As an example, the complete characterization of filtration with monolayer and multilayer deposition of iron oxide colloids is performed using particle-breakthrough curves from coreflooding.
Climate Policy Statement
Authors: Alliance The Blue Green 
Published: July 2009

The four labor unions and two environmental organizations that comprise the Blue Green Alliance worked intensively during the fall of 2008 and winter of 2009 to craft a joint statement on comprehensive climate change policy. The United Steelworkers, Sierra Club, Communications Workers of America, Natural Resources Defense Council, Laborers International Union of North America, and Service Employees International Union together released a policy statement on climate change and energy in late March. The goal of this undertaking is to articulate a framework by which the United States can rapidly put millions of Americans back to work building a clean-energy economy and reducing global warming emissions to avoid the worst effects of climate change.
Fiscal and Externality Rationales for Alcohol Policies
Authors: Parry Ian W. H. , West Sarah E , Laxminarayan Ramanan 
Published: July 2009

Abstract
Alcohol taxes are typically justified as a means to address externalities from alcohol abuse and to raise government revenue. Prior literature has focused on measuring the Pigouvian tax but has paid little attention to the fiscal rationale. This paper presents an analytical and simulation framework for assessing the optimal levels, and welfare effects, of alcohol taxes and drunk driver penalties, accounting for both externalities and how policies interact with the broader fiscal system.Under plausible parameter values and recycling possibilities, the fiscal component of the optimal alcohol tax may be as large, or larger, than the externality-correcting component. Therefore, fiscal considerations can significantly strengthen the case for higher alcohol taxes. They also raise the welfare gains from alcohol taxes relative to those from drunk driver penalties, and they warrant differential taxation of individual beverages on an alcohol equivalent basis.
American Idol: Evidence on Same-Race Preferences
Authors: Lee Jungmin 
Published: July 2009

Abstract
This paper examines whether viewers of the popular television show, American Idol, exhibit racial preferences. We find evidence on same-race preferences among black viewers only: when there are more black contestants in the show, more black viewers are tuned in to watch it. The result is robust after we account for the endogeneity problem regarding the contestants' racial composition, which arises due to the voting mechanism. Our point estimates tell that a 10 percentage point increase in the proportion of black contestants increases viewership ratings for black households by about 1.3 percentage points.
Job Strain in Physical Therapists
Authors: Campo Marc A. , Weiser Sherri , Koenig Karen L. 
Published: July 2009

BackgroundJob stress has been associated with poor outcomes. In focus groups and small-sample surveys, physical therapists have reported high levels of job stress. Studies of job stress in physical therapy with larger samples are needed.ObjectiveThe purposes of this study were: (1) to determine the levels of psychological job demands and job control reported by physical therapists in a national sample, (2) to compare those levels with national norms, and (3) to determine whether high demands, low control, or a combination of both (job strain) increases the risk for turnover or work-related pain.DesignThis was a prospective cohort study with a 1-year follow-up period.MethodsParticipants were randomly selected members of the American Physical Therapy Association (n=882). Exposure assessments included the Job Content Questionnaire (JCQ), a commonly used instrument for evaluation of the psychosocial work environment. Outcomes included job turnover and work-related musculoskeletal disorders.ResultsCompared with national averages, the physical therapists reported moderate job demands and high levels of job control. About 16% of the therapists reported changing jobs during follow-up. Risk factors for turnover included high job demands, low job control, job strain, female sex, and younger age. More than one half of the therapists reported work-related pain. Risk factors for work-related pain included low job control and job strain.LimitationsThe JCQ measures only limited dimensions of the psychosocial work environment. All data were self-reported and subject to associated bias.ConclusionsPhysical therapists’ views of their work environments were positive, including moderate levels of demands and high levels of control. Those therapists with high levels of demands and low levels of control, however, were at increased risk for both turnover and work-related pain. Physical therapists should consider the psychosocial work environment, along with other factors, when choosing a job.
Physiotherapy Practice and Delegation Policies in Oxygen Administration: A Survey of Ontario Hospitals
Authors: Espiritu Olivia , Schaeffer Erin , Bhesania Natasha , Perera Sarah , Dickinson Emma , Nussbaum Ethne , Lai Denise 
Published: July 2009

Purpose: As of 2008, the Regulated Health Professions Act in Ontario stipulates that administration of oxygen is a controlled act, which physiotherapists are not authorized to perform but which may be delegated to physiotherapists by another health professional authorized to perform this act. The aims of this study were (1) to survey physiotherapy practice of oxygen administration in Ontario hospitals and (2) to determine the proportion and characteristics of hospitals with delegation policies for physiotherapists to administer oxygen. Method: Postal surveys were sent to 208 hospitals. Data were collected on hospital characteristics; the presence of delegation policies; and the practice and training of physiotherapists, physiotherapy assistants, and students in oxygen administration. Data were described by summative statistics. Fisher's exact test and Cramer's V statistic were used to examine associations. Potential prognostic factors were analyzed using logistic regression. Results: Response rate was 82.7%. Physiotherapists administered oxygen in 39% of hospitals, and 28% of hospitals had delegation policies. Larger, urban, or teaching hospitals and those with a matrix structure were most likely to have delegation policies and physiotherapists who administered oxygen. Rehabilitation hospitals were also likely to have such policies. Conclusion: Physiotherapists administer oxygen in less than half of Ontario hospitals, very few of which have delegation policies.