bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Dry Oxidation on the Performance of Carbon Nanotube Arrays Electrochemical Capacitors
Authors: Aria Adrianus I. , Gharib Morteza 
Published: March 2012

ABSTRACTIn this study, the effect of dry oxidation on the electrochemical properties of carbon nanotube arrays is investigated. Oxygenated surface functional groups were introduced to the arrays by oxygen plasma treatment, where their surface concentrations were varied by controlling the exposure time. The finding presented herein shows an augmentation of nearly thirty times in term of specific capacitance when the arrays are oxidized. Similar behavior is also observed in the non-aqueous electrolytes where the specific capacitance of the oxidized carbon nanotube arrays is measured more than three times higher than that of the pristine ones. However, overexposure to oxygen plasma treatment reverses this effect. At such high oxidation level, the damage to the graphitic structure becomes more pronounced such that the capacitive behavior of the arrays is overshadowed by their resistive behavior. These findings are important for further development of carbon nanotube based electrochemical capacitors.
Bioinspired Layer-by-Layer Poly(vinyl alcohol) - Graphene Oxide Nanocomposites
Authors: Sellam Charline , Zhai Zhi , Zahabi Hediyeh , Deng Hua , Bilotti Emiliano , Peijs Ton 
Published: March 2012

ABSTRACTA bottom-up approach for poly(vinyl alcohol) (PVA) - graphene oxide (GO) nanocomposites using a spraying method is presented. Very simple and versatile, spraying allows to build-up uniform layered composite films with good control on the structure of each layer. 150 bi-layers were deposited to create a transparent film with improved mechanical properties at a loading of 5.4 wt.% GO. The Young’s modulus and strength of these films doubled or nearly doubled which is believed to be due to a synergic effect as a result of the nanoscale organization of the composite by the 2D nanofiller, and hydrogen bonding between the PVA and the GO.
Management of the Invasive Hill Raspberry (Rubus niveus) on Santiago Island, Galapagos: Eradication or Indefinite Control?
Authors: Renteria Jorge Luis , Gardener Mark R. , Panetta F. Dane , Crawley Mick J. 
Published: March 2012

AbstractThe eradication of an invasive plant species can provide substantial ecological and economic benefits by eliminating completely the negative effects of the weed and reducing the high cost of continuing control. A 5-yr program toward the eradication of hill raspberry (Rubus niveusThunb.) in Santiago Island is evaluated using delimitation and extirpation criteria, as well as assessment of the ecological community response to management techniques. Currently, hill raspberry is located in the humid zone of Santiago island. It is distributed over three main infestations, small patches, and many scattered individuals within an area of approximately 1,000 ha. New infestations are constantly being found; every year, new detections add an area of approximately 175 ha. Adult and juvenile individuals are still found, both beyond and within known infestations. Both plant and seed bank density of hill raspberry decreased over time where infestations were controlled. Species composition in the seed bank and existing vegetation were significantly different between areas under intensive control and adjacent uninvaded forest. After 5 yr of intensive management, delimitation of hill raspberry has not been achieved; new populations are found every year, increasing the infested area that requires management. Off-target effects on native species resulting from control efforts seem to be substantial. Although a vast increase in economic investment would allow intensive searching that might enable all individuals to be found and controlled, the resultant disturbance and off-targets effects could outweigh the conservation benefits of eradication.
Roads as Corridors for Invasive Plant Species: New Evidence from Smooth Bedstraw (Galium mollugo)
Authors: Meunier Geneviève , Lavoie Claude 
Published: March 2012

AbstractRoads function as prime habitats and corridors for invasive plant species, and can contribute significantly to the spread and establishment of weeds inside protected areas. Smooth bedstraw (Galium mollugo) populations have recently expanded in the abandoned agricultural fields of Bic National Park (Quebec, Canada), and may represent a threat to the preservation of plant diversity and to the quality of visitor experience. The main objective of this study was to map the distribution of the species in the park and to delineate factors influencing the abundance of the plant in fallow fields. We hypothesized that road proximity was the main factor explaining the presence and abundance (frequency of recording) of smooth bedstraw in fields. Vegetation surveys were conducted in abandoned agricultural fields, and two logistic regression models were built to examine the relationship between the presence and abundance of smooth bedstraw and environmental and historical variables. Smooth bedstraw populations were also mapped along transportation corridors. The abundance of smooth bedstraw significantly increases within 125 m (410 ft) of a paved road. The recent proliferation of smooth bedstraw in Bic National Park is likely associated with the construction of road embankments during the paving of gravel roads. The paved road network has probably acted as a dispersal corridor for smooth bedstraw, while the abandoned agricultural fields located close to the paved roads provided suitable habitats facilitating population establishment over large areas. We recommended to the park's authorities to cease paving all remaining gravel roads in the park, not only to stop smooth bedstraw invasion, but also the spread of other invasive species of concern.
Long‐term data reveal patterns and controls on stream water chemistry in a forested stream: Walker Branch, Tennessee
Authors: Lutz Brian D. , Mulholland Patrick J. , Bernhardt Emily S. 
Published: March 2012

We present 20 years of weekly stream water chemistry, hydrology, and climate data for the Walker Branch watershed in eastern Tennessee, USA. Since 1989, the watershed has experienced a ∼1.0°C increase in mean annual temperature, a ∼20% decline in precipitation, and a ∼30% increase in forest evapotranspiration rates. As a result, stream runoff has declined by ∼34%. We evaluate long‐term trends in stream water concentrations and fluxes for nine solutes and use wet deposition data to calculate approximate watershed input–output budgets.Dissolved constituents were classified as geochemical solutes (Ca2+, Mg2+, and SO42−) or nutrients (NH4+, NO3−, soluble reactive phosphorus [SRP], total soluble nitrogen [TSN], total soluble phosphorus [TSP], and dissolved organic carbon [DOC]). Geochemical solutes are predominantly controlled by discharge, and the long‐term changes in catchment hydrology have led to significant trends in the concentrations and fluxes of these solutes. Further, the trends in geochemical solute concentrations indicate shifting soil flowpath contributions to streamflow generation through time, with deep groundwater having a greater proportional contribution in recent years.Despite dramatic changes in watershed runoff, there were no trends in inorganic nutrient concentrations (NH4+, NO3−, and SRP). While most nutrients entering the watershed are retained, stream fluxes of nutrient solutes have declined significantly as a result of decreasing runoff. Nutrient concentrations in the stream exhibit large seasonality controlled by in‐stream biological uptake. Stream benthic communities are sensitive to hydrologic disturbance, and changes in the frequency or intensity of storm events through time can affect nutrient fluxes. Stream NO3− concentrations are also sensitive to drought, with concentrations decreasing (increasing) if conditions during the three years prior to the time of sampling were drier (wetter) than the long‐term mean. Future changes in the incidence of storm events, as well as the number and duration of droughts, have the potential to significantly alter watershed nutrient losses.Our analysis indicates that changing climates can differentially affect watershed element cycles either through changes in biogeochemical process rates or through changes in catchment hydrology. Furthermore, climate change can include both long‐term trending in mean climate variables, as well as changes in the frequency and intensity of storms and droughts, with each of these types of change having distinct effects on the biological and geochemical processes governing different solutes.
Incorporating Into Reservoir Models How Nonreservoir Effects Impact Production Data
Authors: Hoffman B. Todd , Gopalan Karthik 
Published: March 2012

Abstract
There are a number of factors that can affect a well's production response that are not caused by the reservoir such as a fluid level in the wellbore, downhole pump inefficiencies, completion irregularities, a poor cement job, undetected formation damage and many others. The first part of this paper demonstrates the variability in the "measured" production data when these issues arise, and shows that the impact can lead to a well that produces significantly less than well that is influenced only by reservoir behavior.
Some of the non-reservoir effects (NRE) are known and included in reservoir models, but many are not known and not included in the models. When reservoir properties are modified to match data that is a function of non-reservoir behavior, we show that model predictions do not perform as well as when the NRE are incorporated. The next section of the paper presents ways to account for the NRE with a conventional reservoir simulator. Techniques are developed to automatically change the simulation models based on historical impact and frequency of the NRE.
The techniques were tested on a real field example with 25 years of historical production. We assumed that only the first 5 years were known and matched just that data, and then predicted the next 20 years using both a traditional model and one that included non-reservoir effects. The model with NRE has the same look as the real data and the prediction error was reduced from 47% to 8%.
In petroleum operations, there are other aspects besides the reservoir that impact the measured production data, and this work shows how to account for those effects. When included, models more accurately predict actual reservoir behavior, which should lead to better decision making about the reservoir.
Integrating Wellbore Hydraulics, Reservoir Properties, and Thermal Transient Analysis for SAGD Injector Well Completion Design with Multiple Outflow Control Devices: A Case Study
Authors: Medina Max , Wat Rex 
Published: March 2012

Abstract
The industry’s approach on SAGD injector well completion design is evolving in complexity by increasing the amount of steam-outflow distribution points along the horizontal wellbore. The main drivers in this evolution process are improved steam conformance and uniform chamber growth. Despite this trend, there are not many technical papers covering the criteria for selecting steam outflow locations, quantity and steam flow rate ratio at each distribution point.
This paper describes a case study of a SAGD injector well completion design comprised of two parallel strings and multiple outflow control devices placed along the well’s long string. We modeled the steam outflow profile into the reservoir with a commercial thermal wellbore simulator, which is coupled to a series of reservoir cells along the horizontal wellbore.
We based the preliminary completion design on the subsurface parameters that control steam flow into the reservoir (i.e. permeability, thickness, bitumen saturation, etc.). We derived these parameters from an up-to-date geological model based on core data, open-hole logs and cuttings analysis. At the end of the well’s circulation phase, we ran a series of temperature falloff logs from planned shut-in periods. We used fiber optic and thermocouple temperature data sets to perform thermal transient analysis, which allowed identifying the location of local/preliminary steam chambers and fingering phenomena. This diagnostic analysis generated a revision on the well’s preliminary completion design and steam outflow reservoir parameters.
We carried out a final design using real SAGD performance data obtained from thermal transient analysis. The design objective was to negate the uncharacteristic steam chamber growth features, developed during the circulation phase, to promote uniform development along the wellbore. This paper provides a methodology and criteria for SAGD injector completion design that can be broadly applied across the industry, integrating wellbore hydraulics, reservoir properties and thermal transient analysis into the design process.
Production Optimization and Forecasting of Shale Gas wells Using Simulation Models and Decline Curve Analysis
Authors: Ikewun Peter , Ahmadi Mohabbat 
Published: March 2012

Abstract
This paper involves the use of simulation models and the decline curve analysis (DCA) as a production optimization and forecasting tools. Production data from three neighboring counties (with high, medium and low cumulative gas productions) of the Eagle Ford shale, an analogue to the Shublik shale of Alaska, was analyzed using the DCA to correlate production performance with completion (horizontal leg/stages of fracture) and length of horizontal leg. We built and run generic simulation models using realistic range of properties. Simulation results provided a better understanding of interplay between static properties and dynamic behavior. The simulation results highlight how and when the key influential elements such as gas desorption, fracture closure with depletion, varying medium and fracture properties, different hydraulic fracture configuration, and various natural fracture networks will affect the well production.
The use of the method proposed in this paper would result in better and more reliable production forecast at the Eagle Ford and other young producing shale reservoirs possessing short production history. The modeling of these complex reservoir geometry and fracture networks would give an extensive understanding of the flow mechanics in shale reservoirs and identify the key parameters affecting production performance. It would also serve as a screening tool for fracturing/re-fracturing operations and give optimal hydraulic fracture configuration for various mediums and natural fracture networks.
Results from the decline curve analysis of 24 producing wells with production histories of 9-57 months showed an increase in reserves with more fracture stages but not at all instances which makes the use of simulation models very valuable and necessary in obtaining further results and explanations. DCA generated different forecast depending on which part of data were used. This clearly indicated the need for running simulations. Simulation runs can generate more reliable production forecast of which the decline part can be used to evaluate the capability of DCA to reproduce the production profiles. The results from simulation can provide a clear picture of the role of key influencing parameters from both reservoir and well stimulation/completion on well production performance.
The results from this study will provide answer to the following questions: How long the production history needs to be for DCA to generate reliable forecasts? &lt;br/&gt; What are the key reservoir and completion elements that strongly affect the production? And what parameters control the choice of well spacing?
The Vedder Lease, Section 9, Mt. Poso Field, California: A Unique Case History
Authors: Evans Barry L. 
Published: March 2012

Abstract
Oil production from the Vedder lease began in 1926 with the discovery of the Mount Poso oil field. Oil production has continued for 86 years and development is continuing. The Vedder lease is in the heart of the Main Area of the field. Following primary production, steamflooding the three Vedder sands resulted in very high recovery factors. The Vedder sands had strong aquifers and each sand required a specific design for steamflooding. Later development has been in the Pyramid Hills sands. This development has featured vertical and horizontal drilling and hydraulic fracturing. It is believed that the Pyramid Hills sands have waterflood potential and could further increase the oil reserves and economic life of the field.
The field was sold by a major oil company in March 1999. Operations have been conducted by three other oil companies since 1999. The field is an example of how smaller oil companies can use new technologies to increase oil production and oil reserves resulting in extending the life of an oil field. The implementation of all these processes has required the use several legal agreements. Over the 86 years the Vedder lease has involved three generations of the Vedder family.
Analytical Study of Effects of Flow Rate, Capillarity and Gravity on CO2/Brine Multiphase Flow System in Horizontal Corefloods
Authors: Kuo Chia-Wei , Benson Sally M. 
Published: March 2012

Abstract
This paper presents an approximate semi-analytical solution for predicting the average steady-state saturation during multiphase core flood experiments over a wide range of capillary and gravity numbers. Recently, the influences of flow rate, gravity, and sub-core heterogeneity on the brine displacement efficiency have been studied using the 3-D simulator TOUGH2 (Kuo et al. 2010). These studies have demonstrated that the average saturation depends on the capillary and gravity numbers in a predictable way.
The purpose of this paper is to provide a simple approximate semi-analytical solution for predicting the average saturation during core flood experiments, thus avoiding the need for 3-D simulations. A two dimensional analysis of the governing equations for the CO2/brine multiphase flow system at steady-state is used to develop the approximate semi-analytical solution. We have developed a new criterion to identify the viscous-dominated regime at core scale. Variations of interfacial tension, core permeability, length of the core, and the effects of buoyancy, capillary and viscous forces are all accounted in the theoretical solutions. We have also shown that three dimensionless numbers (NB, Ngv, Rl) and two critical gravity numbers (Ngv, c1, Ngv, c2) are required to properly capture the balance of viscous, gravity, and capillary forces. There is good agreement of the average saturations between the 3-D simulations and the model. This new model can be used to design and interpret multiphase flow core-flood experiments.
Real-Time Downhole Monitoring of Electrical Submersible Pumps Rated to 250°C Using Fiber Optic Sensors: Case Study and Data Value in the Leismer SAGD Project
Authors: Medina Max , Torres Carlos , Sanchez Julio , Boida Lindsey , Leon Alfredo , Jones Jason , Yicon Carlos 
Published: March 2012

Abstract
Leismer is the first Statoil operated steam-assisted gravity drainage (SAGD) project in the Athabasca region of Alberta, Canada. Electrical submersible pumping systems (ESPs) are the standard artificial lift method for this project. A field trial was planned for newly developed ESPs rated to 250°C. The increased temperature rating allows operating SAGD chambers at higher pressures, thus providing more operational flexibility for increasing recovery and dealing with common exploitation problems. The field trial required reliable and comprehensive down-hole monitoring, so that thorough ESP performance analysis could be performed under real field conditions.
Given the extreme conditions at which ESP systems operate in SAGD, fiber optic pressure and temperature sensors were selected for real-time down-hole monitoring. These sensors were placed at the pump intake, inside the motor and at the discharge. The fiber optic gauges’ performance is comparable to standard SAGD measurement devices, but without some of the disadvantages.
The sensing system configuration, ESP interface and installation will be described. This paper will also present the value of real-time ESP monitoring. The pump operation is controlled by continuously history matching performance with well performance software and adjusting parameters to changing down-hole conditions. This ensures the ESPs are run near the best efficiency point. Pump intake sub-cool is controlled to minimize steam flashing occurrence. ESP motor temperature is monitored to boost reliability and run time. Finally, discharge pressure measurement has been used for history matching multiphase flow correlations. This improves ESP performance calculation accuracy in the field’s other wells.
Integrating ESP advances with fiber optic measurement has allowed effective local technology qualification under real operating conditions. This project has provided abundant information and knowledge for field-wide production optimization.
Combining Absorption and AVO Seismic Attributes Using Neural Networks to High-Grade Gas Prospects
Authors: Rahimi Zeynal A. , Aminzadeh F. , Clifford A. 
Published: March 2012

Abstract
A seismic attribute is a transformation of the original seismic data that can help determine the rock type and fluid characters. AVO attribute analysis is a proven method for confirming seismic amplitude anomalies associated with gas anomalies. AVO analysis examines the intensity of seismic reflections at varying source-receiver distances (offset). The major risk with AVO analysis is whether seismic amplitude anomalies represent commercial or non-commercial gas accumulations. Combining AVO and absorption attributes using ANN reduces this risk. Further risk reduction is accomplished thorough investigation of the different types of absorption attributes and enhancing the ANN training with petrophysical information derived from well logs. We demonstrate that the high frequency content of the seismic response attenuates more as it propagates through gas-bearing reservoirs and, unlike AVO, the absorption attribute is impacted by the amount of gas saturation. Furthermore, we demonstrate how the correlation between shallow gas and shallow seismic amplitudes improves as we include different types of well logs with proper calibration. The ANN, trained by the suite of logs and different frequency-related attributes, enhances the ability to detect undeveloped pockets of shallow gas. Gas has a very marked effect on both density and neutron logs, resulting in lower bulk density and lower apparent neutron porosity. Therefore, combining neutron and density logs and training neural networks based on the well logs with AVO and AQF attributes, instead of just training based on attributes alone, increases the certainty of suspected gas pockets. The real power comes from being able to tie absorption and AVO anomalies with other frequency attributes.