bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact Evaluation of a Public Bicycle Share Program on Cycling: A Case Example of BIXI in Montreal, Quebec
Authors: Fuller Daniel , Gauvin Lise , Kestens Yan , Daniel Mark , Fournier Michel , Morency Patrick , Drouin Louis 
Published: January 2013

Objectives. We examined associations between residential exposure to BIXI (BIcycle-taXI)—a public bicycle share program implemented in Montreal, Quebec, in 2009, which increases accessibility to cycling by making available 5050 bicycles at 405 bicycle docking stations—and likelihood of cycling (BIXI and non-BIXI) in Montreal over the first 2 years of implementation.Methods. Three population-based samples of adults participated in telephone surveys. Data collection occurred at the launch of the program (spring 2009), and at the end of the first (fall 2009) and second (fall 2010) seasons of implementation. Difference in differences models assessed whether greater cycling was observed for those exposed to BIXI compared with those not exposed at each time point.Results. We observed a greater likelihood of cycling for those exposed to the public bicycle share program after the second season of implementation (odds ratio = 2.86; 95% confidence interval = 1.85, 4.42) after we controlled for weather, built environment, and individual variables.Conclusions. The implementation of a public bicycle share program can lead to greater likelihood of cycling among persons living in areas where bicycles are made available.
A Comprehensive Examination of the Influence of State Tobacco Control Programs and Policies on Youth Smoking
Authors: Farrelly Matthew C. , Loomis Brett R. , Han Beth , Gfroerer Joe , Kuiper Nicole , Couzens G. Lance , Dube Shanta , Caraballo Ralph S. 
Published: January 2013

Objectives. We examined the influence of tobacco control policies (tobacco control program expenditures, smoke-free air laws, youth access law compliance, and cigarette prices) on youth smoking outcomes (smoking susceptibility, past-year initiation, current smoking, and established smoking). Methods. We combined data from the 2002 to 2008 National Surveys on Drug Use and Health with state and municipality population data from the US Census Bureau to assess the associations between state tobacco control policy variables and youth smoking outcomes, focusing on youths aged 12 to 17 years. We also examined the influence of policy variables on youth access when these variables were held at 2002 levels. Results. Per capita funding for state tobacco control programs was negatively associated with all 4 smoking outcomes. Smoke-free air laws were negatively associated with all outcomes except past-year initiation, and cigarette prices were associated only with current smoking. We found no association between these outcomes and retailer compliance with youth access laws. Conclusions. Smoke-free air laws and state tobacco control programs are effective strategies for curbing youth smoking.
Hispanic Mortality Paradox: A Systematic Review and Meta-Analysis of the Longitudinal Literature
Authors: Ruiz John M. , Steffen Patrick , Smith Timothy B. 
Published: January 2013

To investigate the possibility of a Hispanic mortality advantage, we conducted a systematic review and meta-analysis of the published longitudinal literature reporting Hispanic individuals’ mortality from any cause compared with any other race/ethnicity. We searched MEDLINE, PubMed, EMBASE, HealthSTAR, and PsycINFO for published literature from January 1990 to July 2010. Across 58 studies (4 615 747 participants), Hispanic populations had a 17.5% lower risk of mortality compared with other racial groups (odds ratio = 0.825; P < .001; 95% confidence interval = 0.75, 0.91). The difference in mortality risk was greater among older populations and varied by preexisting health conditions, with effects apparent for initially healthy samples and those with cardiovascular diseases. The results also differed by racial group: Hispanics had lower overall risk of mortality than did non-Hispanic Whites and non-Hispanic Blacks, but overall higher risk of mortality than did Asian Americans. These findings provided strong evidence of a Hispanic mortality advantage, with implications for conceptualizing and addressing racial/ethnic health disparities.
Early Childhood Lead Exposure and Academic Achievement: Evidence From Detroit Public Schools, 2008–2010
Authors: Zhang Nanhua , Baker Harolyn W. , Tufts Margaret , Raymond Randall E. , Salihu Hamisu , Elliott Michael R. 
Published: January 2013

Objectives. We assessed the long-term effect of early childhood lead exposure on academic achievement in mathematics, science, and reading among elementary and junior high school children. Methods. We linked early childhood blood lead testing surveillance data from the Detroit Department of Health and Wellness Promotion to educational testing data from the Detroit, Michigan, public schools. We used the linked data to investigate the effect of early childhood lead exposure on academic achievement among school-aged children, both marginally and adjusted for grade level, gender, race, language, maternal education, and socioeconomic status. Results. High blood lead levels before age 6 years were strongly associated with poor academic achievement in grades 3, 5, and 8. The odds of scoring less than proficient for those whose blood lead levels were greater than 10 micrograms per deciliter were more than twice the odds for those whose blood lead levels were less than 1 micrograms per deciliter after adjustment for potential confounders. Conclusions. Early childhood lead exposure was negatively associated with academic achievement in elementary and junior high school, after adjusting for key potential confounders. The control of lead poisoning should focus on primary prevention of lead exposure in children and development of special education programs for students with lead poisoning.
Estimating Facies Fields by Use of the Ensemble Kalman Filter and Distance Functions—Applied to Shallow-Marine Environments
Authors: Lorentzen Rolf J. , Nævdal Geir , Shafieirad Ali 
Published: January 2013

Summary
The ensemble Kalman filter (EnKF) is one of the most promising tools for assisted history matching of reservoir models, but challenges remain for applications on complex geological structures (facies fields). In this paper, we propose a method that uses distance functions to estimate such fields. The definition of a distance function is “the shortest distance between a given position in the field and the boundary separating facies types.” The idea behind this approach is that distances have smooth properties, and the distribution of the ensemble in a given gridblock is without multimodality and in better agreement with the EnKF Gaussianity assumptions. The distances are then updated by use of the EnKF and converted to petrophysical parameters when the reservoir simulator is run to the next assimilation time. The approach is flexible and simple and possesses several advantages compared with other existing methods: The input items for the method are facies realizations that can be generated with any preferred geostatistical tool; we ensure that the updated fields always are facies realizations; we ensure the conditioning of the correct facies types at the well location, both initially and during the assimilation steps; and the method does not involve complex modifications of the standard EnKF equations.
The approach presented here is based on an extension of previous work performed by the authors. The novelty of the extension is summarized by the following: Any number of specified facies types can be estimated; one distance function is used for each facies type—at each gridblock, the facies type that corresponds to the distance function with maximal value is selected; there are no restrictions on the structure of the facies field to be estimated; and the methodology is extended to update variations in the petrophysical parameters within each facies type. The first of these extensions is considered the most important because the flexibility regarding the number of facies types is necessary for every real industrial application.
We demonstrate the methodology on a field with shallow-marine-environment characteristics. The conclusions from the example are that the history match is improved, uncertainty is reduced, and the method always returns facies realizations with geological authenticity.
Reduction of Fines Migration by Nanofluids Injection: An Experimental Study
Authors: Habibi A.. , Ahmadi M.. , Pourafshary P.. , Ayatollahi Sh.. , Al-Wahaibi Y.. 
Published: January 2013

Summary
Formation damage of oil reservoirs as a result of fines migration is a major reason for productivity decline. Formation fines are defined as unconfined solid particles present in the pore spaces of formations. Their migration, caused by fluid flow in the reservoir, can cause pore plugging and permeability reduction. In the last 3 decades, many studies have characterized fines and their migration effect on permeability reduction. There are many techniques in the industry to remediate the damage, especially in the near-wellbore region. Nanofluids (NFs) that contain nanoparticles (NPs) exhibit specific properties, including a high tendency for adsorption and being good candidates for injection into the near-wellbore region, because of the small nanoparticle sizes. In this paper, a packed column is used to study the use of different types of NPs to reduce fines migration in synthetic porous materials. Three types of NPs—MgO, SiO2, and Al2O3—are used here to investigate their effects on fines movement. The results indicate that fines may adhere to the matrix grains, hindering their migration, when the porous materials are soaked with NFs. Furthermore, to check the mechanisms of this remediation technique, the effect of nanoparticle concentration and fluid flow rates in the medium on fines detachment was studied. A theoretical model was used to calculate total energy of interaction for the surfaces to check experimental results, which was also validated with scanning electron microscopy (SEM) pictures for samples from synthetic cores. The results showed that addition of 0.1 wt% of MgO and SiO2 NPs reduced fines migration by 15% compared with the reference state. MgO NPs were found to be more effective, even at high fluid rates, when used at a higher concentration, as noticed in the macroscopic and microscopic results.
Numerical Simulation of Steam-Assisted Gravity Drainage With Vertical Slimholes
Authors: Chang J.. , Ivory J.. , Tunney C.. 
Published: January 2013

Summary
Steam-assisted gravity drainage (SAGD) is the primary in-situ recovery method for bitumen from the large Athabasca deposit in Alberta, Canada. SAGD field operations encounter a significant decrease in production performance when low-permeability shale barriers are present in the formation. These layers can reduce SAGD performance and impede the growth of the steam chamber. They also significantly limit the percentage of the deposit from which bitumen can be economically recovered with SAGD. The concept of drilling vertical slimholes to create flow paths through barriers was conceived and investigated at Alberta Innovates-Technology Futures (AITF), formerly the Alberta Research Council. The use of slimholes has the potential to significantly increase the amount of recoverable bitumen (reserves) and the rate at which it is produced during SAGD. For shallow reservoirs, the slimholes could be drilled from the surface at a relatively low cost. It is believed that the process can be economically viable after its technical operation has been optimized with improvements in drilling technology, slimhole size and spacing, and enhanced usage of the slimholes in the development of steam chambers above the shale layers. Alternatively, the slimholes could be drilled from the horizontal wellbores (to avoid surface disturbance) as either horizontal slimholes from the producer or as horizontal/vertical slimhole combinations from the injector.
The 2D and 3D field-scale numerical simulations were performed by use of reservoir properties and operating conditions based on published information for the MacKay River SAGD operation in the Athabasca deposit. The reservoir depth was 135 m, the initial pressure 500 kPaa, the initial temperature 7.5°C, and the initial oil saturation (SO) 0.8. The simulations explored the effect of vertical slimholes, which were laterally offset 7 m from the horizontal well-pair in reservoirs with and without shale layers or shale lenses. The effects on SAGD performance that were investigated were slimhole cross section (25 cm × 25 cm or 50 cm × 50 cm), the distance between slimholes (12 or 24 m) in the direction parallel to the well pair, the permeability of the reservoir and the vertical slimholes, and horizontal slimholes from the injector or producer. The slimhole cross section represents the disturbed area adjacent to the drilled slimhole and the drilled hole itself and is therefore relatively large. The slimholes were represented as high-permeability vertical channels by use of refined grids. For a reservoir with a continuous shale layer, SAGD performance was improved by vertical slimholes because of the recovery of previously inaccessible oil from above the shale layer, where a secondary steam chamber was formed.
A New Unified Diffusion—Viscous-Flow Model Based on Pore-Level Studies of Tight Gas Formations
Authors: Rahmanian Mohammad R. , Aguilera Roberto , Kantzas Apostolos 
Published: January 2013

SummaryIn this study, single-phase gas-flow simulation that considers slippage effects through a network of slots and microfractures is presented. The statistical parameters for network construction were extracted from petrographic work in tight porous media of the Nikanassin Group in the Western Canada Sedimentary Basin (WCSB). Furthermore, correlations between Klinkenberg slippage effect and absolute permeability have been developed as well as a new unified flow model in which Knudsen number acts implicitly as a flow-regime indicator. A detailed understanding of fluid flow at microscale levels in tight porous media is essential to establish and develop techniques for economic flow rate and recovery. Choosing an appropriate equation for flow through a single element of the network is crucial; this equation must include geometry and other structural features that affect the flow as well as all variation of fluid properties with pressure. Disregarding these details in a single element of porous media can easily lead to flow misinterpretation at the macroscopic scale. Because of the wide flow-path-size distribution in tight porous media, a variety of flow regimes can exist in the equivalent network. Two distinct flow regimes, viscous flow and free molecular flow, are in either side of this flow-regime spectrum. Because the nature of these two types of flow is categorically different, finding/adjusting a unified flow model is problematic. The complication stems from the fact that the viscosity concept misses its meaning as the flow regime changes from viscous to free molecular flow in which a diffusion-like mechanism dominates. For each specified flow regime, the appropriate equations for different geometries are studied. In addition, different unified flow models available in the literature are critically investigated. Simulation of gas flow through the constructed network at different mean flow pressures leads to investigating the functionality of the Klinkenberg factor with permeability of the porous media and pore-level structure.
A Novel and Comprehensive Study of Polymeric and Traditional Phosphonate Inhibitors for High-Temperature Scale Control
Authors: Wang Wei , Kan Amy T. , Tomson Mason B. 
Published: January 2013

Summary
A novel barite-inhibition assay based on the nucleation and inhibition model has been proposed and used to evaluate the thermal stability of phosphonates and polymeric scale inhibitors with regard to their potential application in high-temperature wells. Systematic experiments have been conducted to investigate the time (minutes to days) and temperature (up to 200°C) dependence of inhibitor thermal degradation, the impact of stainless steel and iron on the degradation of inhibitors at high temperatures, and the difference between aging tests with inhibitors in solution and with those inhibitors adsorbed on core materials. The results not only enable a more accurate understanding of the thermal degradation of scale inhibitors but also facilitate the selection and placement of scale inhibitors for high-temperature oil and gas production.
Nanopore-Structure Analysis and Permeability Predictions for a Tight Gas Siltstone Reservoir by Use of Low-Pressure Adsorption and Mercury-Intrusion Techniques
Authors: Clarkson C.R.. R. , Wood J.M.. M. , Burgis S.E.. E. , Aquino S.D.. D. , Freeman M.. 
Published: January 2013

Summary
The pore structure of unconventional gas reservoirs, despite having a significant impact on hydrocarbon storage and transport, has historically been difficult to characterize because of a wide pore-size distribution (PSD), with a significant pore volume (PV) in the nanopore range. A variety of methods is typically required to characterize the full pore spectrum, with each individual technique limited to a certain pore size range.
In this work, we investigate the use of nondestructive, low-pressure adsorption methods, in particular low-pressure N2 adsorption analysis, to infer pore shape and to determine PSDs of a tight gas silt-stone reservoir in western Canada. Unlike previous studies, core-plug samples, not crushed samples, are used for isotherm analysis, allowing an undisturbed pore structure (i.e., uncrushed) to be analyzed. Furthermore, the core plugs used for isotherm analysis are subsamples (end pieces) of cores for which mercury-injection capillary pressure (MICP) and permeability measurements were previously performed, allowing a more direct comparison with these techniques. PSDs, determined from two isotherm interpretation methods [Barrett-Joyner-Halenda (BJH) theory and density functional theory (DFT)], are in reasonable agreement with MICP data for the portion of the PSD sampled by both. The pore geometry is interpreted as slot-shaped, as inferred from isotherm hysteresis loop shape, the agreement between adsorption- and MICP-derived dominant pore sizes, scanning-electron-microscope (SEM) imaging, and the character of measured permeability stress dependence. Although correlations between inorganic composition and total organic carbon (TOC) and between dominant pore-throat size and permeability are weak, the sample with the lowest illite clay and TOC content has the largest dominant pore-throat size and highest permeability, as estimated from MICP. The presence of stress relief-induced microfractures, however, appears to affect laboratory-derived (pressure-decay and pulse-decay) estimates of permeability for some samples, even after application of confining pressure.
On the basis of the premise of slot-shaped pore geometry, fractured rock models (matchstick and cube) were used to predict absolute permeability, by use of dominant pore-throat size from MICP/adsorption analysis and porosity measured under confining pressure. The predictions are reasonable, although permeability is mostly overpredicted for samples that are unaffected by stress-release fractures. The conceptual model used to justify the application of these models is slot pores at grain boundaries or between organic matter and framework grains.
Blockage Detection and Characterization in Natural Gas Pipelines by Transient Pressure-Wave Reflection Analysis
Authors: Adeleke Najeem , Ityokumbul Mku T. , Adewumi Michael 
Published: January 2013

Summary
Pipeline blockage is a major problem in gas production and transportation processes. Safety and economic costs of pipeline blockages are compelling the industry to design innovative means for early detection of partial blockages along pipe systems as a preventive measure. This paper presents a simple numerical model to be used for accurate blockage characterization in natural gas pipelines. The transport phenomenon is modeled with a quasi-1D set of partial differential equations for isothermal natural gas flow in pipes. The variable area formulation maintains the simplicity of a 1D formulation and yet allows for the complex geometries associated with natural gas pipeline blockages. Viscous effects are also included in the formulation of the governing equations, and a cubic equation of state is incorporated into the model to provide the quasi-compositional effect of real gases without the complexities of a fully compositional model. The generalized Newton-Raphson technique is used to solve the piece-wise finite-volume formulation iteratively as an optimization problem with pressure and velocity as perturbed variables. Reflected pressure waves observed at the pipe inlet node were analyzed for blockage characterization. It was observed that viscous losses have no effect on blockage length and location prediction accuracy, but has significant impact on the accuracy of blockage severity predictions.
Surface Complexation Modeling for Waterflooding of Sandstones
Authors: Brady Patrick V. , Krumhansl James L. 
Published: January 2013

Summary
A theoretical surface coordination model of oil attraction to sandstone-reservoir surfaces confirms the two primary oil/mineral coordination reactions to be electrostatic linking of anionic kaolinite-edge sites to protonated nitrogen bases at pH &lt; 6 and calcium carboxylate groups at pH &gt; 6. Kaolinite basal planes are calculated to link to oil through oil –NH+ groups at pH &lt; 6–7 and through oil –COOCa+ groups at pH &gt; 6–7, and may be important to oil attraction where basal planes are more exposed than edges (the ranges shift, depending on the oil, acid, and base numbers). Model predictions are most sensitive to the dissociation constant of oil surface carboxylate groups but are relatively insensitive to other surface equilibria and temperature. The model shows that, although low-salinity, low-Ca waterfloods can enhance oil recovery by decreasing the number of Ca2+ bridges and anionic kaolinite-edge sites, dissolution of sandstone carbonate minerals dampens the low-salinity effect by buffering decreases in waterflood Ca2+ levels. Better model predictions require more-accurate predictions of Ca2+ levels during waterflooding, high-temperature sulfate-adsorption analyses, and more-precise measurements of oil acidity and basicity.
Simultaneous Continuous Monitoring of the Drilling-Fluid Friction Factor and Density
Authors: Carlsen Liv A. , Rolland Nils Lennart , Nygaard Gerhard , Time Rune 
Published: January 2013

Summary
This paper introduces a method to enable continuous automatic online updates of the density and frictional effects of the drilling fluid during drilling operations. The placement of differential-pressure sensors along the circulation path from the rig pump to the connection to the drillstring enables the fluid properties to be examined more thoroughly at various flow rates, pressures, and temperatures. The paper presents results from a full-scale test in which different fluids were examined. The results show that the method may give reliable data on the main drilling-fluid properties, which are important in all drilling operations, and especially in automatic modes.