bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nano-Proppants for Fracture Conductivity Improvement and Fluid Loss Reduction
Authors: Bose Charles C , Gul Awais , Fairchild Brian , Jones Teddy , Barati Reza 
Published: April 2015

Abstract
Hydraulic fracturing has been proved as a successful technology to increase productivity of ultra-tight shale oil and shale gas reservoirs. Although higher concentrations of polymer were traditionally used for conventional fractures, “linear gels”, “waterfracs”, “slick-water” and ”hybrid” fluids have been typically applied for tight shale plays as we produce from formations with lower permeability and higher brittleness. Fracturing jobs in tight shale plays tend to generate or extend a network of fractures while a bi-wing fracture was typically generated in conventional reservoirs. This network of fractures includes a large network of micro-fractures opened during the injection of fracturing fluids. Small fractures tend to close under closure stress unless a nano-sized proppant with significant stress resistance is injected to keep these micro-fractures opened. Although very high conductivity is not required for very low permeability formations, an open fracture or micro-fracture performs better than a collapsed fracture.
Proppants with different mesh sizes of 20/40, 30/50, 40/70, 70/140 and 80/200 with grain diameters ranging from 0.033 inch (0.8382 mm) to 0.0041 inch (104.14 μm) have been used during hydraulic fracturing of tight shale formations. These proppants are large enough to create conductivity in the larger generated or existing fractures but not small enough to penetrate into the existing or generated micro-fractures. This will cause the closure of micro-fractures at the end of a fracturing job thus reduction in the length and conductivity of the complex fracture network. This reduction in the fracture network extension will reduce production from tight shale formations.
The objective of this work is to investigate size, nano-hardness, reduced elastic modulus, fluid loss prevention capabilities as well as their induced fracture conductivity by nano-proppants from a currently known waste product.
Transmission Electron Microscope (TEM) images showed that nano-proppants had particle sizes varying from 100 nm to 1 μm. Particles showed hardness and reduced elastic moduli of 1.3 GPa and 20 GPa, respectively. These properties show potential for these nanoparticles to be used as proppants to keep fractures open under stress.
Fluid loss tests were conducted using 1% (w/w) concentrations of nanoparticles mixed with 2% (w/w) of KCl, cross-linked guar solutions, and cross-linked guar solutions mixed with 1 % concentration of nanoparticles and significant fluid loss reduction was observed for one of several types of nanoparticles. These nanoparticles generated significant conductivity when used as proppants in an API fracture conductivity test. Fracture permeability values of 27-33 mD were generated using these nano-proppants.
Use of nanoparticles prior to the placement of larger proppants is recommended in order to prevent fluid loss into the formation, and also increase the conductivity of the fissures and micro-sized fractures.
Shifts in the Fundamental Frequency of a Fluid Conveying Pipe Immersed in a Viscous Fluid for use in the Optimization of an Energy Harvesting System to be Deployed in a Producing Hydrocarbon Well
Authors: Kjolsing E. , Todd M. 
Published: April 2015

Abstract
Novel methods for harvesting energy in down hole applications are desired. Specifically, it is hoped that sufficient power can be generated near a hydrocarbon reservoir to operate commercially available well monitoring equipment. Vibration based harvesters are the most likely systems to be developed. The efficiency of such harvesters is highly dependent on the natural frequency of the structural system. To optimize the harvester design, the dynamic properties of the down hole system must be characterized.
This paper presents the results of an analytical frequency study undertaken to identify the role axial force effects, annulus fluid geometry, and annulus fluid properties have on the first natural frequency of a production string as the conveyed fluid velocity was varied. The system was modeled using an Euler-Bernoulli formulation and includes a hydrodynamic forcing function to account for annulus fluid effects. The problem was solved in the frequency domain using the spectral element method, which conveniently provides natural frequency information.
The results of the study are in-line with previously published studies on analogous systems. It was found that the well annulus geometry, annulus fluid density, and annulus fluid viscosity have a strong role in determining the behavior of the system. Additionally, the axial force, added mass, and viscous effects were found to shift the natural frequency of the system while only axial force and viscous effects cause a shift in the fluid velocity at which bifurcation occurs. These findings, along with the method outlined in this paper, provide a useful tool in the characterization of hydrocarbon producing wells which is a first step towards developing an energy harvesting system.
Although the problem of determining the dynamics of a fluid conveying pipe immersed in a viscous fluid has been approached using a shell formulation in the past, to the authors knowledge this is the first time the problem has been solved with a beam formulation.
Approved for publication, LA-UR-15-21089. Copyright for this paper have been transferred to SPE.
Reservoir Waterflooding System Identification and Model Validation with Injection/Production Rate Fluctuations
Authors: Rezapour A. , Ortega A. , Ershaghi I. 
Published: April 2015

Abstract
Describing injector-producer relationships in waterflooding with a Linear Time Invariant (LTI) model is mainly based on black box modeling techniques, where the model parameters do not necessarily have physical interpretation. Therefore, the question is whether one can be certain about the range of the estimated parameters and their validity when they cannot be verified with measurements. In this paper, we will show the connection between the conditions on the training data and the reliability of the predictions of the mathematical models. Our results show that if the injection rates (before and after water break through) have variations at relatively low frequencies and without high amplitude, then the identified models with well-known model parameterization, such as capacitance model, have accurate predictions. The observations in this research imply that for obtaining reliable models; (i) one must find the appropriate amplitude and frequency for injection rate fluctuations, (ii) while keeping the reservoir condition and its working point in linear (or close to linear) regime. Otherwise, the model identification becomes unreliable, since the models that are used in practice tend to be LTI.
Improved Proxy For History Matching Using Proxy-for-data Approach And Reduced Order Modeling
Authors: He Jincong , Xie Jiang , Wen Xian-Huan , Chen Wen 
Published: April 2015

Abstract
Response surface proxies are commonly used in history matching process to approximate the functional relationship between the input parameters and the aggregated mismatch. The quality of the proxy (accuracy in prediction) degrades as the nonlinearity of the response surface increases. However, commonly-used definitions of aggregated mismatch, such as root mean squared error (RMSE) or mean absolute error (MAE), are highly nonlinear. As a result, the quality of the proxy for aggregated mismatch can be unsatisfying in many cases.
In this work we propose the proxy-for-data approach, in which one proxy is built for each observation data point and then the data values predicted by those proxies are used to calculate the aggregated mismatch. Because proxies are constructed for the data themselves rather than for the aggregated mismatch, the nonlinearity of the aggregated mismatch definition will not affect the quality of the proxy. It is shown in multiple test cases that the new approach consistently improves proxy quality for different types of proxies and different aggregated mismatch definitions. For cases with large amount of observation data points, we also show that the use of reduced-order modeling can efficiently reduce the number of proxies needed and achieve similar improvement. The new approach is successfully applied to both synthetic and field examples and both examples show improved proxy quality.
An Analytical Comparison of Wellbore Deviation and its Effects on Proper Centralization in the Bakken
Authors: Fry Dominik , Pruett Bradley 
Published: April 2015

Abstract
The effects of centralization on the quality of a cement job should not be underestimated. Poor centralization promotes channeling and poor removal of drilling mud/filter cake. Even the best designed cement might not perform if mud is left in the hole with cement on just one side of the wellbore. Computer simulations are effective tools in predicting ideal centralizer placement, but placement is frequently based solely off planned wellbore data. The general well plan in North Dakota is to drill vertically until kicking off to drill the horizontal section through the Bakken formation. In theory, a casing string will stay centralized without any centralizers in a truly vertical wellbore. This has led to the use of only a sparse number of centralizers, even though many cement bond logs can show poor bonding far below the desired top of cement. In cases of poor isolation the state regulatory agency might require an additional string to be run for the stimulation procedure, as well as cathodic protection on the casing.
A sampling of wells spaced throughout the Bakken was put into a deviation analysis. All wells were planned vertical until the desired kickoff point. These wells were analyzed for trends in deviation, dog leg severity, and required centralizer spacing to achieve the desired standoff. Sections of the wellbores were identified with higher tendencies towards deviation from the desired well path. The average required centralization was determined and rules were generated based off dog leg severity and deviation. These rules were used to create an optimized centralization schedule, which was tested against the original wellbores.
The results clearly show that the planned vertical section is rarely vertical. While the deviation from plan varies widely, even small deviations impact centralization significantly. This is likely one of the first analysis done on multiple wells to analyze the influence of prejob planning on cementing in the Bakken. Because of the thorough analysis on past operations, a more robust design can be proposed for real-world conditions in the future.
Decision-Useful Asset Measurement from a Business Valuation Perspective
Authors: Botosan Christine A. , Huffman Adrienna A. 
Published: April 2015

SYNOPSIS
This article proposes an approach to asset measurement rooted in business valuation theory and practice. In the context of a business valuation, investors' information needs and the asset measurement investors find useful vary with the manner in which the assets are expected to realize value for the firm. After reviewing arguments made in economic and accounting theory, accounting research, accounting standards, and practitioner and business valuation literature, we conclude that for in-exchange assets, investors need to determine the value expected to be realized in exchange. Exit price in a hypothetical market exchange (i.e., fair value) less expected costs to sell provides investors with decision-useful information in this regard; replacement cost and historical cost do not. For in-use assets investors require information useful in forecasting cash flows generated by using such assets in combination. Based on arguments and data presented in the aforementioned literature, we conclude that historical cost generally provides investors with decision-useful information for forecasting purposes; fair value does not. In addition, replacement cost can provide decision-useful information provided holding gains and losses are separately disclosed, but its decision-usefulness can be constrained by verifiability concerns.
Anterior Ischemic Optical Neuropathy in Children on Chronic Peritoneal Dialysis: Report of 7 Cases
Authors: Di Zazzo Giacomo , Guzzo Isabella , De Galasso Lara , Fortunato Michele , Leozappa Giovanna , Peruzzi Licia , Vidal Enrico , Corrado Ciro , Verrina Enrico , Picca Stefano , Emma Francesco 
Published: April 2015

Background Anterior ischemic optic neuropathy (AION) is characterized by infarction of the optic nerve head due to hypoperfusion of the posterior ciliary arteries and causes sudden blindness in adults on chronic dialysis, but has rarely been described in children. Unlike adults, children do not have comorbidities related to aging. Methods We retrospectively analyzed data of 7 children on nocturnal continuous cycling peritoneal dialysis (CCPD) who developed AION identified within the Italian Registry of Pediatric Chronic Dialysis. We also summarized data from 10 cases reported in the literature. Results Our 7 patients suffered from acute onset bilateral blindness. Their mean age was 3.2 years and chronic hypotension had been observed prior the AION in 3 of the 7 children. Low systolic blood pressure (SBP) was associated with higher risk of developing AION according to statistical analysis. None recovered completely. In total, 11 out of 16 experienced a partial recovery and no clear evidence emerged favoring specific treatments. Conclusions Hypotensive children treated with CCPD are at increased risk of developing AION, which often results in irreversible blindness.
Taxa and names in Cynoglossum sensu lato (Boraginaceae, Cynoglosseae): an annotated, synonymic inventory, with links to the protologues and mention of original material
Authors: Hilger Hartmut , Greuter Werner , Stier Victoria 
Published: April 2015

An inventory is presented of all names so far validly published in Cynoglossum sensu lato and its segregate genera: Adelocaryum, Afrotysonia, Kuschakewiczia, Lindelofia, Mattiastrum, Paracaryum, Rindera, Solenanthus, Trachelanthus, and their synonyms. Names and designations that were not validly published in the cited place, and later isonyms, are accounted for when they have been included in the International Plant Name Index (IPNI). Problems with IPNI entries, including errors and omissions, are discussed, and the hope is expressed that the present inventory may be of use for fixing them.
The inventory, generated from a list of structured data, is presented in two Supplements, as a searchable HTML document comprising a sequence of entries with internal cross-links and links to external sources, in particular to protologues accessible online or, copyright restrictions permitting, made available as scanned documents via DOIs, and as machine-readible file. With minor exceptions, all names have been verified in their original place of publication, and all were nomenclaturally assessed. Colour coding is used to distinguish between names (in green) pertaining to Cynoglossum sensu lato, for which complete synonymies are provided; and names (in orange) pertaining to other genera but published under Cynoglossum or its segregates. They are listed together with their basionym and the corresponding correct name (if it exists), but without complete synonymy. Acceptable, potentially correct names appear in bold-face type, both under a broadly defined Cynoglossum (for which purpose validation of 81 new combinations and the name of 1 new species was necessary) and under one or more of its segregates. When a name was published for a new taxon, original material is indicated, usually by direct quotation from the protologue. New type designations are exceptional (two cases), whereas former type designations are cited whenever known. Furthermore, types and original specimens, especially when their digital images are available online, are mentioned with their locations and accession numbers. Comments are added whenever appropriate, especially to explain nomenclatural assessments that are not self-evident.
Black flies (Diptera: Simuliidae) of Turkish Thrace, with a new record for Turkey
Authors: Şirin Ümit , Çalışkan Hakan , Şahin Yalçın 
Published: April 2015

This paper includes 2742 specimens of 18 species of black flies (Diptera: Simuliidae) collected from 132 lotic sites in Turkish Thrace, the European part of Turkey, in the early summer of 2002 and 2003 and the spring of 2005 and 2006.
All species are recorded from this region for the first time, and Metacnephia nigra (Rubtsov, 1940) is a new record for Turkey. Distributional and taxonomical remarks are given for each species.
Embracing a vision of the New Jerusalem (Rv 21:1−22:5) to impact on life and society
Authors: Pohlmann Martin H. 
Published: April 2015

Apocalyptic biblical literature has played a significant role in motivating and mobilising Christians. As part of this genre, the Apocalypse of John has played this mobilising role within the church throughout its history. Jerusalem is often incorporated into this genre to conjure up different emotions and images to impact many different people. For example, the Jew annually recites the words to fellow Jews at every Passover meal: ‘Next year in Jerusalem’. Most Christians know the hymn ‘The holy city’, originally penned by Frederic Weatherly in 1892. It lifts many a spirit as it conjures up the idea of a beautiful, perfect, heavenly city of God. However, there is more to this apocalyptic vision, which will be explored in this article. The city upholds the hope of decent godly living today. Whilst Jerusalem is a city with an extremely chequered history, it remains to be the launching pad of a dream that believers can embrace in order to impact society for the better. The vision in Revelation 21–22 is the launch of the ‘idea’ of God’s intention for society today, and the ‘implementation impetus’ is the primary role of the church. In the greater scheme of things, the world community is the target group for a better society for everyone.Aanneming van ’n visioen van die Nuwe Jerusalem (Op 21:1–22:5) ten einde ’n invloed op lewe en die samelewing uit te oefen. Apokaliptiese Bybelliteratuur het ’n beduidende rol in die motivering en aansporing van Christengemeenskappe gespeel. Die Openbaring van Johannes het hierdie motiveringsrol deurgaans in die geskiedenis van die kerkas deel van dié genre vertolk. Jerusalem is dikwels hierby ingesluit om ’n verskeidenheid van emosies en beelde op te roep ten einde ’n impak op ’n verskeidenheid mense te maak. Die Jood, byvoorbeeld, haal jaarliks die volgende woorde teenoor mede-Jode tydens die Paasmaaltyd aan: ‘Volgende jaar in Jerusalem’. Die meeste Christene ken die gesang ‘The holy city’ wat oorspronklik deur Frederic Weatherly in 1892 geskryf is. Dit hef menige gelowiges se gemoedere op omdat dit die beeld van ’n pragtige, perfekte stad van God oproep. Daar is egter meer aan hierdie openbaringsuitsig wat in hierdie artikel verder ondersoek word. Die hemelstad bekragtig die hoop vir ’n godvrugtige lewe vandag. Alhoewel Jerusalem ’n stad met ’n uiters veelbewoë geskiedenis is, is dit tog die beginpunt vir hierdie droom van gelowiges om die samelewing te verbeter. Die visioen in Openbaring 21–22 is die bekendstelling van die ‘idee’ van God se bedoeling vir ons hedendaagse samelewing en die ‘vervullende beweegkrag’ is die primêre rol van die kerk. Holisties beskou, is die wêreldgemeenskap die teikengroep vir ’n beter samelewing vir almal.
Analogs of Luteinizing Hormone-Releasing Hormone in the Treatment of Endometriosis
Authors: Engel Jörg B. , Tinneberg Hans R. , Block Norman L. , Berkes Eniko , Schally Andrew V. 
Published: April 2015

Agonists of luteinizing hormone-releasing hormone (LHRH) induce a reversible hypoestrogenic state through the down-regulation of LHRH receptors and desensitization of the pituitary. Since endometrial implants are estrogen sensitive, LHRH agonists have frequently been used for medical treatment of endometriosis. Nowadays, LHRH agonists can be considered in general as a second-line medical treatment for endometriosis-related symptoms, as oral therapy with dienogest is as effective and has fewer side effects. However, therapy with LHRH agonists for 3-6 months prior to in vitro fertilization remains the treatment of choice in patients with endometriosis, as it significantly increases pregnancy rates. LHRH agonists are used prior to surgery and as an adjuvant after an operation to prevent recurrence or prolong disease-free intervals. Adverse effects of LHRH agonists are due to hypoestrogenism and include hot flushes, vaginal dryness, loss of libido, sleep disturbances and a diminished bone density which limits the duration of their administration to 6 months. For long-term treatment, add-back of estrogen and/or progestin,/or progestin only with or without bisphosphonates, can be used, but existing studies only cover a 12-month period of treatment. LHRH antagonists competitively block the pituitary receptors for LHRH. Consequently, a partial pharmacological hypophysectomy with a reduction of the estrogen levels to a desired level is possible if LHRH antagonists are adequately dosed. As endometriotic implants require relatively high levels of estrogen, partially lower plasma levels of estrogens are sufficient to prevent the loss of bone density. A long-term treatment without add-back therapy is also possible.
Why we should not skip aspirin in cardiovascular prevention
Authors: Schrör K. 
Published: April 2015

SummarySince more than 20 years, aspirin is an approved and established first-line antiplatelet medication in cardiovascular prevention. This is partially due to ist unique mode of action which is not shared with any other antiplatelet agent as well by the reliability of its pharmacological efficacy: inhibition of platelet COX-1 and subsequent thromboxane formation in almost every patient. Aspirin acts synergistic with ADP-antagonists in dual antiplatelet therapy of acute coronary syndroms (ACS) and percutaneous coronary interventions (PCI) and is also approved for long-term secondary prevention. Patients with atrial fibrillation are an exception and benefit more from anticoagulants. After the introduction of the new oral anticoagulants (NOACs), i.e. direct inhibitors of factor Xa or thrombin formation, there is a renewed discussion about the role of antiplatelet agents, specifically if additional dual antiplatelet treatment is still necessary for an optimum clinical effect or whether one component, such as aspirin might be skipped in favor of other classes of oral antiplatelet agents, such as ADP-antagonists. The available data are insufficient to recommend this because of a low number of studies and a still uncertain benefit/ risk (bleeding) ratio. More research on aspirin as a chemopreventive appears also to be necessary and is going on, in particular in individuals at high-risk for vascular thrombotic diseases (diabetics, preeclampsia, venous thrombembolism).