bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Implementation of the First CO2-EOR Demonstration Project in Saudi Arabia
Authors: Kokal Sunil , Sanni Modiu , Alhashboul Almohannad
Published: September 2016

Enhanced oil recovery (EOR) using CO2 is an important recovery process that can increase recoverable hydrocarbons and sequester CO2 simultaneously. For light oils, CO2 injection is particularly interesting and is considered a win-win strategy that sequesters CO2 and provides additional oil reserves at the same time.

Saudi Aramco has designed and implemented the first CO2-EOR demonstration project in one of the fields. It is worth mentioning that while Saudi Aramco does not require EOR oil for decades to come, this project is being pursued primarily to demonstrate the feasibility of sequestering CO2 through EOR in the Kingdom and using it as grounds to test new monitoring and surveillance (M&S) techniques. The project consists of two components: the actual EOR project in a small part of a field, and the CO2 capture plant. An overall plan covering laboratory and research studies, reservoir modeling and simulation, monitoring and surveillance, construction of a CO2 capture facility, project implementation and evaluation will be presented for this first demonstration project.

The project uses 40 million standard cubic feet per day (MMscf/d) of CO2 that is being captured and processed from an existing facility and piped about 85 km to the field location. An innovative progressive infill line drive has been implemented to take advantage of the east-west fluxes in the field. This includes a row of four injectors and four producers, and another set of observations wells for monitoring and surveillance. The CO2 is being injected in a water-alternating-gas (WAG) mode. An elaborate monitoring and surveillance program has been established and currently being implemented to evaluate the performance of the project. It includes the deployment of several new technologies including seismic, inter-well tracers, gravity, geochemical sampling and analyses that will be discussed in the paper.

The main objectives of the demonstration project are estimation of sequestered CO2, determination of incremental oil recovery, addressing the risks and uncertainties involved, including migration of CO2 within the reservoir and operational concerns. It is estimated that up to ~40% of the injected CO2 will be sequestered permanently in the reservoir.
Investigation of Methods to Rotate Casing Sections Independent of Surface Rotation
Authors: Fleckenstein W. W. , Eustes A. W. , Yaakob G. H. , Rostad R. D.
Published: September 2016

It has long been recognized that the movement of casing can improve cement jobs and assist in running casing in challenging well trajectories. Both reciprocation and rotation of casing relies upon the use of the rig at the surface to rotate or reciprocate the entire casing string, which may be undesirable for operational or safety considerations. Rotation of casing from the surface may also result in unacceptable stresses on the casing string. This paper presents the results of an investigation into a method to rotate a section of the casing without the use of surface rotation, but instead using a hydraulic device to rotate a specific section of the casing. In many applications, the most critical portion of the casing to achieve a quality cement job and resultant seal in the annulus between the casing and the borehole is the bottom sections of the casing. A method is presented to rotate a section of casing by the use of a hydraulic device placed below the float collar, which rotates a section of casing from the bottom up. This casing section is decoupled from the non-rotating section of the casing by means of a sealed rotation element, allowing only critical section(s) of the casing to be rotated. The placement of the hydraulic device below the float collar allows the device to be drilled up or left encapsulated in cement, for operational efficiency. The casing rotation is imparted hydraulically by the use of a rotary mechanical device that extracts energy from a fluid flow and causes the section of casing to rotate in response to a fluid being pumped through, such as cement, spacers and drilling fluids. Modeling of a variety of hydraulic device configurations and experimental experience with several prototypes using surface tests at low hydraulic horsepower configurations indicate that sections of casing can be rotated hydraulically for various applications. Several different configurations of downhole devices were examined, and were capable of a variety of rotational speeds and torques, depending on the specific application that the casing is rotated for. Multiple devices may be used in tandem to produce more hydraulic horsepower, as needed for a desired application, or to provide rotation at several critical areas.
Prevention of Halite Formation and Deposition in Horizontal Wellbores: A Multi Basin Developmental Study
Authors: Hebert Jeff , Leasure Josh , Saldungaray Pedro , Ceramics Carbo
Published: September 2016

Halite scale is a wide spread problem throughout several basins in the United States. This scale can form in surface equipment, downhole tubulars as well as affecting production. Traditional remediation of halite can be accomplished by dissolving the scale in fresh water as well as recycled water. In most cases the operator must factor in the cost of fresh water, trucking, manpower, anti-scale additives, and disposal of additional produced water. These treatments are often frequent with multiple applications per week.

The approach described in this paper will prevent the formation of halite scale for a given period of time. This is accomplished through the use of a new porous ceramic proppant-based chemical delivery system in which a halite inhibitor is infused. The infused halite inhibitor is encapsulated with a semi-permeable membrane to regulate the elution rate of the inhibitor from the porous proppant carrier. The chemical delivery system is added to the bulk proppant as a small weight percentage of the bulk proppant and is placed in the fracture as normal proppant.

Several wells in the multiple basins for several E&P companies were completed using this new chemical delivery system, which allowed for a significant amount of halite inhibitor to be placed within the proppant pack. As fluids flowed over the proppant pack the halite inhibitor was slowly released. This paper intends to describe the mechanism for which the inhibitor acts, the control release mechanism of the substrate and the engineering behind the placement and volumes of the halite infused proppant. This paper will also discuss the data collected from laboratory modeling and the implementation of these products in fracturing applications. The use of this chemical delivery system will allow these operators to defer remediation, lowering lease operating expenses.

This paper will be useful to all production and completions engineers and technicians operating in an area with halite scale issues. This new chemical delivery system allows for deferred implementation of traditional remediation strategies while extending the most productive time of the wells life. This halite inhibitor delivery system not only improves estimated ultimate recovery but also lowers lease operating expenses.
Calibrated Clay Parameter Improves Continuous Permeability Estimation with LWD Logs in Complex Siliciclastic Reservoirs
Authors: Li Xingli , Lu Yunlong , Zhu Jianmin , Wang Xijie , Li Ting , Zhang Lei
Published: September 2016

For conventional reservoirs, matrix permeability is a crucial petrophysical parameter for completion design and reservoir characterization. However, direct measurement of permeability is difficult to obtain through well logging. Traditionally, continuous permeability is estimated from porosity log using relationships derived from core measurements. This method can result in inaccurate permeability values when there's a poor correlation between porosity and permeability.

It has been shown previously that the kΛ equation can accurately estimate permeability when applied to log data. This equation computes permeability from lithology weight fractions by associating a specific surface area (S0) value with each lithology. In general, S0 for sand and carbonate are well defined and stable. However, the specific surface area for clay (S0clay) depends largely on clay type and can be highly variable from reservoir to reservoir. Since clay has the most significant effect on permeability, the wrong assumption on S0clay will lead to strong bias in the interpretation results.

In modern logging programs, formation pressure tests are commonly included for reservoir characterization. By observing pressure behavior versus time in a pretest, one can directly measure fluid mobility at discrete stations. We can then use the measured fluid mobility to calibrate S0clay and compute a continuous permeability log. Here is the workflow:Zone the well such that the clay is of the same type within the zones.Using a univariate optimization routine, find S0clay the value that minimizes the sum of squared difference between permeability from pressure tests and permeability from well logs within the zone.Use the calibrated S0 for clay to compute a continuous permeability log from quantitative lithology.

In this report, we demonstrate that in a complex sandstone reservoir containing interbedded sand and shale, the variability in permeability is fully captured by the continuous permeability log. The calibrated clay S0 ensures that the interpreted permeability matches measured permeability from pressure tests.
Oil Droplet Removal from Produced Water Using Nanoparticles and Their Magnetic Separation
Authors: Ko Saebom , Kim Eun Song , Park Siman , Daigle Hugh , Milner Thomas E. , Huh Chun , Bennetzen Martin V. , Geremia Giuliano A.
Published: September 2016

The removal of highly stable dispersed oil produced during oil recovery processes is very challenging, especially in offshore operations where the limited space does not allow use of equipment with long residence time for the required separation. Using magnetic nanoparticles (MNPs) to remove the dispersed oil from produced water is a promising way to overcome the difficulties that the current treatment technologies face, since the MNPs-attached oil droplets can be quickly and efficiently separated with application of an external magnetic field. The MNPs can be also regenerated and reused, minimizing the generation of hazardous waste. We investigated not only the optimal operating conditions, such as MNP concentration and salinity, but also the mechanisms of MNPs-oil attachment and magnetic separation.

We synthesized MNPs in the laboratory with a prescribed surface coating. The MNPs were superparamagnetic with an average individual particle size of ~10 nm. Crude oil content in separated water was reduced by as much as 99.9% using MNP concentrations as low as 0.04 wt% in 5 minutes after MNPs and oil were reacted.

The electrostatic attraction between negatively charged oil-in-water emulsions and positively charged MNPs controls the attachment of MNPs to the droplet surface; and the subsequent aggregation of the electrically neutral MNPs-attached oil droplets plays a critical role for accelerated and efficient magnetic separation. The particle aggregation occurred fast, generally within one minute. Thus, the total magnetic separation time was dramatically reduced to as short as 1 second, contrary to that of free, individual MNPs where it took about 36~72 hours, depending on the MNP concentrations.

Model calculations of magnetic separation velocity, accounting for the MNP magnetization and viscous drag, show that the velocity of free Amine functionalized MNPs (A-MNPs) increases about 1~3 orders of magnitude as the particles get closer to the magnet depending on the particle size. The smaller the particles, the greater the effect of the magnetic field on the velocity. A typical operating condition would be when the size of the MNPs-oil droplet aggregates is grown to be greater than 360 nm. Then, the total magnetic separation time will be approximately 5 minutes.
Wellbore Stability Analysis Based on Sensitivity and Uncertainty Analysis
Authors: Niño Fernando Antonio
Published: September 2016

A methodology based on sensitivity and uncertainty analysis is presented for performing a wellbore stability analysis in order to quantify model uncertainty and improve the predictions made. This methodology is applied to the safe mud window design for a study case.

A wellbore stability model is set up, as of constitutive equation and failure criteria selection. Based on available data, a stochastic approach is used to assess the uncertainty associated to input parameters, or otherwise other alternatives like expert opinion are utilized. Secondly, a sensitivity analysis is carried out by means of OAT and RSM methods displaying results on tornado and spider diagrams. Finally, an uncertainty analysis is performed using Monte Carlo simulations for quantifying uncertainty in model outputs and obtaining the required mud weight to drill successfully as a probability function.

Four approaches for assessing uncertainty in input data of wellbore stability models are presented. Sensitivity analyses showed maximum horizontal stress and cohesion as the most critical parameters in collapse pressure determination while minimum and maximum horizontal stresses were the major variables in fracture pressure evaluation. On other hand, vertical stress and Poisson ratio were considered as constants during the uncertainty evaluation due to their subtle impact in model results. Ultimately, an uncertainty analysis is presented via probabilistic graphs, which enables a better decision making since uncertainty in input data is considered and safe mud window is obtained as a probability function of drilling successfully.

The workflow proposed makes up a complete uncertainty study useful for developing wellbore stability analyses which optimizes the decision making in drilling process design. Aspects like evaluation of input data uncertainty and incorporation of sensitivity analyses are novel components for complementing the simulation Montecarlo as uncertainty analysis method and risk analysis tool.
Development of Software Application for Optimization of Primary Cementing Operations Using Visual Basic
Authors: Chaudhry Abdul Manan
Published: September 2016

Scientific software development is a multi-step process, involving good understanding of the mathematical model, development of an algorithm and subsequently its implementation as a computational code.

Using these methodologies an open source Cementing Operations software library has been coded. A software application "Cementing Operations Calculator" has been developed over this library, which efficiently provides solutions for primary cementing operations.

The software helps in selecting optimum parameters for primary cementing operations such as Displacement Volume, Lead Slurry Total Volume, Tail Slurry Total Volume, Lead Slurry Composition (quantity of cement & cement additives), Tail Slurry Composition (quantity of cement & cement additives), Lead Slurry Composition (Dead Volume), Tail Slurry Composition (Dead Volume) and finally the Chemicals required for performing the primary cementing operations job.

A number of geoscientific computational libraries are available in the public domain which have been initiated by various universities and developed and maintained by a large community of developers. Keeping in view the same trend, there is a need for developing open source libraries for petroleum engineering. Thus the aim of this research is to provide open source code which is publicly available to the others to enhance and incorporate new functionality. In addition the software tools are also publicly available which can be used by students and researchers for analysis of their data. The use of the software is demonstrated with real field data examples.
Adaptive Grid Refinement Improves Gas Injection Modeling
Authors: Gonzalez Karin G.
Published: September 2016

This paper introduces a new method to create adaptive mesh refinement and coarsening in compositional reservoir simulation. The methodology targets individual cells for refinement based on forecasted compositional fronts calculated using streamlines and the analytical convection-dispersive transport equation. Quadtree decomposition determines the optimal spatial discretization across the simulation grid using dynamic and static reservoir properties. Application of the new approach results in improved computational performance and better representation of complex fluid behavior.

Current dynamic gridding implementations have rigid schemes, posing two major limitations: cell refinement size is a pre-determined input value and compositional maps from the previous time step define the refinement region. This solution leads to suboptimal modeling due to time-lagging refinement and lack of grid adaptability in heterogeneous reservoirs and/or fast-moving compositional fronts. The new methodology overcomes these limitations by combining streamline and particle trajectory to forecast the injection front location and adapt grid sizes in advance.

Tracking compositional variations starts by calculating fluxes for all cells using the finite-difference solution. Next, Pollock's tracing method allows reducing the 3-dimensional model into a series of 1-dimensional streamlines, while the convection-dispersive equation forecasts future compositions, shape, and location of injection front along each streamline trajectory. Finally, quadtree decomposition analyzes the homogeneity of dynamic and/or static properties (e.g., composition, pressure, permeability, facies) to determine if a volume can be represented by a single gridblock or if it requires refinement to preserve spatial details. Grid discretization is dynamic over time, refining cells requiring high-resolution and/or coarsening those with low variation.

A mechanistic model with CO2 injection served to evaluate the methodology. The fluid was modeled with five pseudo-components and the Peng-Robison equation of state with volume translation to improve volumetric predictions. The new approach reduced the total number of cells required to model miscible injection by continuously creating adaptive grids that represent the advancement and shape of the injection front. Results showed a reduction in computational cost between 30-63% over a static fine grid without compromising the representation of compositional mixing phenomena and production forecast.
3-D Reconstruction of Porous Media and Rock Characterization
Authors: Naraghi Morteza Elahi
Published: September 2016

The transport and elastic properties of a rock are functions of the pore size distribution, geometry and morphology. Due to limited availability of 3-D micro-structure images of rocks, several attempts to theoretically model the behavior of rocks have been made. However, all such methods have limitations. In addition, 3-D micro-structure images of rocks, even if available, represent only a small volume of the rock, and the predictions of macroscale properties based on them are uncertain. In this study, a new stochastic method to reconstruct a 3-D model for the rock using only a 2-D section of the imaged rock sample is proposed. The proposed method is a combination of a multiple point statistics simulation, gradual deformation of images, and calculation of transport and elastic properties. The first step is to generate multiple independent realizations by performing multiple-point statistics based stochastic simulations. These simulations represent independent 2-D scans through the rock volume. Next, a succession of images is generated spanning two adjacent independent sections. These images are generated so as to gradually morph features from one section to those in the next independent section. These 2-D images are then stacked together to reconstruct the 3-D image.

After reconstruction, transport and elastic properties of the reconstructed image are computed. For a test case for which the measured rock properties are available, the results obtained using the reconstructed image reveal that the calculated properties are close to the measured values. Finally, we generated multiple realizations with different porosity values, where the shape of pores and grains are preserved. We studied the sensitivity of the elastic properties to the porosity of the samples. The results provide insights on the effect of cementation or increased overburden pressure on flow and mechanical properties of rocks.
Capturing Complex Reservoir Heterogeneity in a Field Under Water Injection – A Case Study of a Niger Delta Field
Authors: Nanaghan Karena O.
Published: September 2016

Structural heterogeneity is one of the critical factors that can affect a reservoir's performance, properties and thus, its ultimate recovery. With the decline in oil price and continuous drive for cost optimisation, understanding the impact of such features on reservoir behaviour in terms of pressure communication, fluid movement, production and well placement becomes paramount.

In this research paper, the main study subject is a compartmentalised reservoir in a mature Niger Delta field undergoing water injection. Two blocks in the reservoir separated by a fault mapped from the seismic which was believed to be non-sealing as initial pressure data acquired from both blocks through aRepeat Formation Test(RFT) were similar; suggesting that these blocks were in hydraulic communication.

Production started from the western block in 2001, and after few years of production, a significant drop in reservoir pressure was observed. To arrest this pressure decline, water injection into the reservoir commenced in 2011. After four years of injection, a substantial increase in reservoir pressure was observed as confirmed from static bottom hole pressure surveys from existing wells in the block.

With the successful implementation of pressure maintenance and oil being swept updip structure as suggested by the history matched reservoir model, infill well opportunities were identified in the western and eastern parts of the A block. In order to properly land these wells, reduce production uncertainty and ensure its successful production, a pilot hole was drilled into these blocks to ascertain current fluid contacts and reservoir pressure. Information from the RFT was however surprising as reservoir pressure in the eastern block was found to be significantly depleted contrary to expectations; as similar pressure with the western block was expected since there was no producer in this block.

This paper describes how an integrated approach resulted in significant cost saving and how an analytical tool like the multi tank material balance methods was used to effectively characterise a complex reservoir under water injection and revise the field redevelopment plan.
An Extension of Johnson, Bossler and Neumann JBN Method for Calculating Relative Permeabilities
Authors: Abbas Mamudu
Published: September 2016

The Johnson, Bossler and Neumann (JBN) method is the industry standard for measuring relative permeabilities from field cores. Mitigating the numerical errors resulting from the numerical differentiation required by the method has been an area of interest over the years. There have been several modifications of this technique by many researchers in order to improve the results. Some of the researchers have used curve fitting and graphical approach. However, till date, the application of a numerical modeling technique to do the necessary numerical differentiation of the data required by the JBN method for improved results is yet to be established.

This paper presents the application of cubic spline numerical modeling technique (CSNMT) on JBN method. Production data from field cores were used. The JBN technique was initiated procedurally. The necessary numerical differentiation of the production data required by the JBN method was done with cubic spline numerical modeling technique (CSNMT). Tridiagonal system of equations was formed and resolved. Different and continuous equations (polynomials) were derived for the contiguous intervals and then differentiated accordingly. The procedure was then accomplished.

The technique shows good results which are close to those obtained when the numerical differentiation is done the traditional way, using an expression for an unequally spaced data gotten from the numerical differentiation of a second-order langrage interpolating polynomial for three data points. However, because of the oscillations induced and the difficulty in handling higher order polynomials numerically which leads to the use of second-order langrage interpolating polynomial instead of a polynomial of order one minus the number of the data points required, the results from the use of CSNMT are more reliable. In addition, the profiles of the production data are modeled in CSNMT. The reduction in the overall numerical error was reflected by the differences in the relative permeability values obtained by both approaches.
Hierarchical Geological Realism for Reliable Reservoir Predictions
Authors: Kuznetsova Alexandra
Published: September 2016

In the current oil price situation it is particularly important to improve the reliability of reservoir forecasts to make better field development decisions. The great challenge of reservoir modelling is to account for geological uncertainty to increase reliability of the predictions.

The aim of this paper is to explore and answer three important questions that tackle this challenge and affect reservoir predictions.

The first question is: to what extent does geological realism matter to reservoir predictions? To estimate the value of geological realism to reservoir predictions we introduce hierarchical geological realism into facies modelling. It allows us to account for geological realism at three different levels: 1) multiple possible geological concepts, 2) geological consistency of each geological concept, 3) geologically realistic relations of model parameters, such as: geobodies dimensions and facies proportions. Implementation of multiple possible geological concepts allows us to include interpretational uncertainty for more realistic predictions.

The second question is: how to maintain geological realism during model update? Automated history matching requires model updates to achieve a good match between observed and simulated data. Geological realism can easily be lost during a model perturbation whilst history matching. We aim to maintain geological realism through model the update process by using a metric space approach. Classification of models in the metric space provides geologically realistic differentiation between multiple possible geological concepts. The result of the classification allows us to predict a geologically realistic model description through the model update process.

Finally, we ask: can geological realism improve the reliability of the forecast? To answer this question we test the hierarchical approach in automated history matching on a West Coast of Africa reservoir. The results validate the choice of geological scenario and improve the reliability of the forecast.
Dynamic Hybrid Modelling Framework for Resources Management in Exporting Under-Developed and Developing Nations
Authors: Echendu Joseph C.
Published: September 2016

Most reserves growth models have focused on mature fields in developed nations. Consequently, the direct application of such models to under-developed and developing nations with perceived maturing fields becomes challenging as the fundamental assumption in existing model formulations do not apply and are violated. The resultant resource management policies thus fail to meet the yearnings and aspirations of many under-developed and/or developing petroleum-dependent economies.

This work bridges this gap using the formulation of a hybrid model that captures the peculiarity of under-developed and developing nations with attendant maturing field, towards their resources management. The modelling framework entails a hybrid of discovery-process, econometrics, and discounted cash flow approaches. However, for the purpose of this paper, policy application of the latter is the focus.

Discounted Cash Flow (DCF) model framework adopted in this paper; is used to evaluate and investigate the impacts of volatility of oil price on oil and gas development economics using conventional, linear and logarithmic scales' fiscal policy schemes. Economic performance indicators such as Internal Rate of Return (IRR), Profitability Index (PI), and Take statistics are incorporated to evaluate investment performance. Sensitivity simulation approach is also incorporated to investigate its impact on decision variables. The overall aim is mitigating associated economic and technical risks in the highly risky and capital intensive oil and gas industry during low oil price regime.

This paper recommends that resources utilization emphasis should be geared towards value addition by providing incentives that encourages more investment domestically, thereby opening up opportunities for its citizenry. Paradoxically, incentivizing and delaying gratification that encourages investments tend to yield approximate economic performance metrics as perceived regressive fiscal terms that would not encourage upstream E&P investments, ceteris paribus.
Analysis of Production Rates of a Gas Well Using Computational Fluid Dynamics and Rate-Dependent Pseudo-Skin Factor
Authors: Molina Oscar
Published: September 2016

This paper investigates the impact of high-rate production on well performance of a cased-hole gas well with a fracpack type of completion. We modeled fluid dynamics in the near wellbore region, where the most drastic changes in pressure, velocity and temperature are expected to occur, using a computational fluid dynamics approach.

Fluid flow modeling was based on Navier-Stokes equations coupled with Forchheimer equation, which enabled us to study inertial and turbulence effects in regions where velocity suddenly increases and then decreases in the same way in a relatively small length scale. In addition, gas properties were incorporated into the momentum balance equation via the Soave-Redlich-Kwong equation of state. Simulations were pressure-driven at steady-state and isothermal conditions so that external pressure was kept constant and pressure at the wellbore was varied to generate the well performance curve for the simulation model.

The concept of rate-dependent pseudo-skin factor was then introduced as a tool to assess the level of nonlinearity caused by inertial and turbulence kinetic energy losses at different pressure drawdowns. Analysis of simulation results showed that rate-dependent pseudo-skin went from a negative value at low rates to positive at medium-to-high producing rates. This is because inertial and turbulence effects were negligible at low superficial velocity, hence negative skin factor of completion prevailed, while the opposite happens at high superficial velocity. Therefore, we hypothesize that optimum operating condition of a well is at the maximum possible flow rate at which inertial and turbulence kinetic energy losses are minimum; we found this condition coincides with the well flowing condition at which the rate-dependent pseudo-skin is zero.
RECIPIENTES E SUBSTRATOS NA PRODUÇÃO DE MUDAS DE JATOBÁ (Hymenaea courbaril L.)
Authors: Gonzaga Luciana De Moura , Silva Sarah Santos da , Campos Silvane De Almeida , Ferreira Rodrigo De Paula , Campos André Narvaes da Rocha , Cunha Ana Catarina Monteiro Carvalho Mori da
Published: September 2016

O objetivo deste estudo foi avaliar diferentes recipientes e substratos na produção de mudas de jatobá (Hymenaea courbaril L.), arbórea nativa da família Caesalpinioideae. O delineamento utilizado foi inteiramente ao acaso com 2 recipientes (tubete e sacola plástica) e 10 formulações de substratos (misturas de solo, esterco bovino - EB, cama aviária de poedeiras - CA, fertilizante químico e areia, em diferentes proporções). Aos 210 dias após semeadura foram avaliadas as variáveis: altura da parte aérea, diâmetro do colo, matéria seca da parte aérea, radicular, e total, e calculado os índices de qualidade das mudas. Foi realizada a quantificação de esporos de fungos micorrízicos arbusculares (FMAs) e a normalização por meio de correção ESPOROS/MSR. Na maioria das características avaliadas, não houve diferença significativa entre os substratos testados, o que possibilita o uso de acordo com o custo e a disponibilidade local de cada. A sacola plástica e os substratos de origem animal possibilitaram maiores ganhos de biomassa às mudas. Quanto ao número de esporos de FMAs os maiores valores foram observados em substratos contendo CA em tubete. Recomenda-se para a produção de mudas de jatobá: sacola plástica e o substrato com 60% solo + 20% areia + 20% CA.
GESTÃO E AVALIAÇÃO DA ARBORIZAÇÃO DE ÁREAS PÚBLICAS NO MUNICÍPIO DE BOM JESUS-PIAUÍ
Authors: De Oliveira Robson José , Silva Ana Lúcia Alves da , Da Silva Elisabete Oliveira da , Sant’Anna Giovani Levi , França Luciano Cavalcante de Jesus
Published: September 2016

Este estudo teve como objetivo analisar a arborização nas áreas públicas no município de Bom Jesus, Sul do Piauí, enfocando a importância da arborização urbana, sua contribuição na qualidade de vida e manutenção do ecossistema urbano. Foram avaliadas três praças públicas dispostas em diferentes locais do município. O levantamento dos dados foi realizado por meio de amostragem aleatória. A amostragem foi realizada com 11 indivíduos arbóreos, distribuídos em cinco espécies exóticas e seis nativas. Foram avaliados: infraestrutura das praças, espécie, fiação, vias e calçadas. Dentre os indivíduos avaliados, as espécies predominantes foram: Inga vera (Sombreiro) e Licania tomentosa (Oiti). Todos os indivíduos apresentaram algum grau de inadequação, estando alguns inseridos em locais com a presença de fiação, telefone público e em espaçamento de calçadas errados.
Singing Psalms with owls: a Venda twentieth century musical history
Authors: Kruger Jaco
Published: September 2016

World historiography of the second half of the twentieth century has been marked by the expansion of historical subject matter. Bundy (1991:94-95) notes of American historiography that â€œnew methodologies, new sources of evidence, new themes and concepts have not only transformed existing specialist fields of enquiry but also called into being entirely new genres and sub-disciplinesâ€. South African historiography has lagged behind in this respect, and it is only in recent years that themes in social history have emerged. These include demography, the family, youth, old age, death, crime, leisure, health, education and law (Bundy 1991:100). Bundy (1991:99-100) furthermore notes that the study of these themes has not yet been taken far, while â€œentire areas of the past remain blankâ€. While artistic cultural forms like literature, orature, graphic and plastic art, theatre, dance and music are receiving increasing historical attention, they too still have to enter mainstream historiography. Furthermore, within the domain of these artistic forms, musical perspectives in particular are inadequately represented in historical reconstruction.
The Impact of Microfinance Institution on Development of Small and Medium Enterprises: A Case Study of Lagos State
Authors: Bagudu Hauwa Daniyan , Khan Shazida Jan Mohd , Roslan Abdul Hakim
Published: September 2016

The major target of this study is to evaluate the effect of Microfinance Institution (MFIs) on the development of SMEs (Small and medium enterprises) in Lagos state Nigeria. Simple random techniques of sampling were employed in this study in selecting 70 SMEs which constituted the size of the sample of the research. To facilitate the obtaining of relevant data that was used for analysis in this study, structured questionnaire was designed. Descriptive statistics involving simple graphical charts and tables was strategically applied in presentation and analysis of data. The outcome of the findings indicates that large number of SMEs are benefiting from the loans granted by the MFIs, despite the fact that few of them have sufficient ability to secure the needed amount. Interestingly, most of the SMEs admit positive MFIs loans contribution towards advancing their market share, the economic competitive advantage of the company and achieving market excellence through product innovation.
Arena, FMLN y los sucesos del 5 de julio del 2006 en El Salvador: violencia e imaginarios políticos
Authors: Sprenkels Ralph
Published: September 2016

Graves disturbios ocurrieron el día 5 de julio del 2006 en El Salvador. La violencia política más grave de la posguerra salvadoreña hasta esa fecha se pagó con dos policías muertos, varios heridos y decenas de detenidos. Después de estos hechos, se produjo otra batalla: explicar lo sucedido y encontrar a los culpables. Ese 5 de julio marcó la culminación en la polarización política entre el partido de derecha Alianza Republicana Nacionalista (Arena), partido de gobierno en ese momento; y el de izquierda, el Frente Farabundo Martí para la Liberación Nacional (fmln), entonces principal partido de oposición. A través de una reconstrucción longitudinal, el presente artículo analiza lo que los hechos –así como las interpretaciones y manipulaciones– pueden enseñarnos sobre la dinámica política de la posguerra salvadoreña. Llama la atención la vigencia de imaginarios políticos asociados a la utilización de los métodos conspirativos y con claros antecedentes en el conflicto armado salvadoreño y la Guerra Fría.
The Triple Aim and its Implications on the Management of Chronic Rhinosinusitis
Authors: Barry Jonnae Y. , McCrary Hilary C. , Kent Sean , Saleh Ahlam A. , Chang Eugene H. , Chiu Alexander G.
Published: September 2016

Introduction

Accountable care organizations (ACO) and alternative payment models are a sign of the change in reimbursement from fee-for-service to value-based reimbursement. The focus of health care under ACOs is represented by the Triple Aim: to improve the experience of health care, improve the health of populations, and reduce the per capita costs. Individuals with chronic rhinosinusitis (CRS) are heavy consumers of health care services. Results of recent studies have indicated that there is the potential for improved outcomes and cost savings from early surgical intervention. Adhering to the principles of the Triple Aim may signal a paradigm shift in regard to timing of intervention for CRS in certain patients.

Methods

A scoping review was performed to analyze the current literature related to management of CRS and the impact on cost, population health outcomes, and the patient's experience of health care.

Results

A growing body of literature indicates that, in appropriately selected patients, when compared with medical management, endoscopic sinus surgery has the potential to improve patient outcomes and reduce the long-term cost burden of CRS.

Conclusion

With the advent of ACOs, a paradigm shift in the treatment of CRS is inevitable to better conform to the goals of the Triple Aim. Future treatment algorithms will need to account for the heterogeneity within CRS and seek to identify appropriate timing and interventions for patients on an individual basis if the value of health care is to be improved.
Open versus Endoscopic Medial Orbital Decompression: Utilization, Cost, and Operating Room Time
Authors: Ference Elisabeth H. , Sindwani Raj , Tan Bruce K. , Chandra Rakesh K. , Kern Robert C. , Conley David , Smith Stephanie Shintani
Published: September 2016

Background

The advent of endoscopic sinus surgery has created an exciting interface between rhinology and ophthalmology in the area of orbital and optic nerve decompression

Objectives

(1) To study the utilization of open versus endoscopic medial orbital decompression based on geography and indication, (2) to describe the demographics of the patient populations who underwent these different techniques, and (3) to compare outcomes, including mean charges and operating room (OR) times

Methods

Cases identified by Current Procedural and Terminology codes were extracted from the California, Florida, Maryland, and New York State Ambulatory Surgery Databases from 2009 to 2011. Patient demographics, diagnoses, mean charge, and OR time were compared.

Results

A total of 1009 patients underwent orbital decompression; 93.0% of cases involved the medial wall only; 22.9% of medial decompressions were performed endoscopically, 74.5% were open, and 2.6% were via combined approach. Eighty percent of patients had thyroid eye disease. Analyses adjusted for sex, age, race, state, and diagnosis found that surgeries for infection (N = 47) were more likely to be performed endoscopically compared with procedures for other diagnoses (N = 962) (odds ratio 5.27 [2.67-10.40], p < 0.001). Patients in Florida were more likely to undergo endoscopic decompression compared with patients in California (odds ratio 2.35 [1.42-3.62]). The difference in median charge for endoscopic ($13,119) versus open ($11,291; p = 0.085) procedures was not significant on bivariate analysis but was significant on multivariate analysis (p = 0.04). The median OR time for open procedures was, on average, 33 minutes shorter (endoscopic, 132 minutes; open, 98 minutes; p ≤ 0.001) on bivariate analysis but was not significantly different when controlling for covariables (p = 0.08).

Conclusion

In the study sample, endoscopic orbital decompression was performed in 22.9% of patients, with significant variation in surgical technique based on geography and indication. Procedures that used endoscopic compared with open decompression techniques had no significant difference in charge on bivariate analysis. The OR time for open procedures was shorter on bivariate but not on multivariate analysis. Further research is required regarding the relative effectiveness of open versus endoscopic surgical techniques for various indications
Immunoglobulin G4-related Sclerosing Disease of the Paranasal Sinuses: A Case Report and Literature Review
Authors: Vandjelovic Nathan D. , Humphreys Ian M.
Published: September 2016

Objective

Immunoglobulin G4 (IgG4) related sclerosing disease (RSD) of the paranasal sinuses is a rare lesion of dense lymphoplasmacytic tissue, with a high proportion of IgG4+ plasma cells. We presented a rare case of IgG4-RSD with isolated involvement of the paranasal sinuses in the absence of multiorgan involvement.

Methods

A case report and comprehensive literature review.

Results

To our knowledge, only 11 cases of IgG4-RSD with paranasal sinus involvement have been reported. Patients with IgG4-RSD commonly present with epistaxis and symptoms that mimic chronic rhinosinusitis, e.g., rhinorrhea, nasal obstruction, and facial pressure. On imaging, an expansive and erosive process is described. Surgery provides tissue for immunohistologic evaluation; however, there is a paucity of evidence about the direct extent of surgical resection or medical therapies. Postoperative steroids were typically started, although the regimen was not standardized.

Conclusion

Few cases of paranasal sinus IgG4-RSD have been reported in the literature. Evidence-based recommendations regarding treatment and surveillance of paranasal sinus IgG4-RSD are lacking; however, most reports describe systemic steroids as the mainstay of treatment. This single subject analysis, with a review of previously reported cases adds to the expanding body of data related to this rare disorder.
Redesigning Rail Transit Short-Turn Operations: Case Study of Line 2 of the Shanghai Metro in China
Authors: Sun Yanshuo , Schonfeld Paul M. , Lu Yi , Zhou Ming
Published: September 2016

A practical problem in the operations of Line 2 of the Shanghai Metro in China—the severe congestion at the Guanglan Road station—led to the proposal of a total cost (including both operator’s and users’ costs) minimization model for redesigning short-turn operations. Existing studies were extended mainly by relaxing the assumption that the full-length route must be operated because this assumption was determined to be needlessly strict and could, therefore, lead to inferior solutions. Flexible models were designed to accommodate more complex combinations of train routes and to calculate potential waiting costs if no direct services were available for some origin–destination pairs. The method was tested through real-world case studies, and major findings were interpreted. Future research directions are also suggested.
Planning Urban Ring Rail Transit Lines: Case Study of Shanghai, China
Authors: Saidi Saeid , Ji Yuxiong , Cheng Cheng , Guan Jinping , Jiang Shengchuan , Kattan Lina , Du Yuchuan , Wirasinghe S. C.
Published: September 2016

Shanghai, China, has the largest metro system in the world, with a network length of more than 550 km. Both Shanghai and Beijing are among the top five cities in terms of ridership, and some of the most important components of their metro systems are the ring transit lines. Many other cities, in China and elsewhere, also envision a ring transit line for their future rail transit networks. A previously developed analytical model for the long-range planning of ring transit lines was used in the comparison of the current alignment of the Shanghai ring line with the optimized model output, and a second ring transit line was recommended for the future Shanghai network. The findings suggest that the alignment of an existing ring line would affect the optimal alignment of the second ring line. In addition, if an outer ring line exists (or is planned to be constructed), the optimal location of the inner ring line might not be its current location. Furthermore, a sensitivity analysis was conducted to test the impact of changes on demand, value of time, and passenger ride cost on the second ring line. Zones that would benefit most from introduction of the second ring line were also determined. Although the case study presents the Shanghai ring lines, the outcomes provide useful information for other cities that are considering the expansion of their transit network with a first or second ring line. Unlike simulations and agent-based models, the model presented in this study is easily transferable to any transit network.
Integrated Line Planning and Train Scheduling for an Urban Rail Transit Line
Authors: Wang Y. , Pan X. , Su S. , Cao F. , Tang T. , Ning B. , De Schutter B.
Published: September 2016

An integrated model for line planning and train scheduling based on the circulation of trains is proposed to reduce passenger dissatisfaction and operation costs for an urban rail transit line. The turnaround operations of trains and their departures from and arrivals at the depot were included in this model. Furthermore, binary variables were introduced to indicate whether train service existed, and a discrete event model was used to determine the order of the train services. In addition, a bi-level optimization approach is proposed to solve the integrated line-planning and train-scheduling problem, in which the number of required train services, the headways between train services, the departure times, and the arrival times were optimized simultaneously on the basis of passenger demand. The performance of the proposed integrated model and bi-level approach is illustrated with a case study of the Beijing Yizhuang line.