bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clinical Experience with Ranolazine in a Veteran Population with Chronic Stable Angina
Authors: Reeder Don N , Gillette Michael A , Franck Andrew J , Frohnapple David J 
Published: January 2012

BACKGROUND: Efficacy of ranolazine in the treatment of chronic stable angina (CSA) has been established; however, pivotal trials did not require the optimization of conventional antianginal drug therapy (CADT) prior to use in a veteran population. OBJECTIVE: To determine whether ranolazine, when added to optimized doses of CADT, improves angina in a veteran population with CSA and refractory symptoms. METHODS: In an observational retrospective study, 35 patients prescribed ranolazine and having a baseline Seattle Angina Questionnaire (SAQ) administered at a Veterans Affairs medical center in Gainesville, FL, were evaluated. Patients who were prescribed ranolazine by a provider from outside the institution and did not obtain a baseline SAQ were excluded. The primary outcome measure was the change in SAQ scores from baseline to 1 and 3 months after initiation of ranolazine treatment. Secondary measures included clinically significant QTc interval prolongation (>500 msec or an increase of at least 60 msec from baseline), adverse drug reactions, discontinuation rates, and drug-drug interactions. RESULTS: The addition of ranolazine to optimized CADT was associated with improvement in all dimensions of the SAQ scores at 1 and 3 months compared to baseline scores (p < 0.001 for all dimensions). Mean changes in SAQ dimension scores at 1 and 3 months, respectively, were as follows: physical limitation, +9.86 and +11.94; angina stability, +39.29 and +32.69; angina frequency, +26.79 and +25.38; treatment satisfaction, +11.38 and +10.66; and disease perception, +16.85 and +18.59. Improvments in all dimensions, except treatment satisfaction, were clinically significant as defined by set criteria. Of the 7 patients whose ranolazine dosages were increased to 1000 mg twice daily, only 2 patients were able to maintain treatment at that dosage. CONCLUSIONS: Ranolazine added to optimized doses of CADT demonstrated an improvement in angina symptoms when given to a veteran population with persistent CSA.
Mitochondrial Genome Maintenance: Roles for Nuclear Nonhomologous End-Joining Proteins inSaccharomyces cerevisiae
Authors: Kalifa Lidza , Quintana Daniel F , Schiraldi Laura K , Phadnis Naina , Coles Garry L , Sia Rey A , Sia Elaine A 
Published: January 2012

AbstractMitochondrial DNA (mtDNA) deletions are associated with sporadic and inherited diseases and age-associated neurodegenerative disorders. Approximately 85% of mtDNA deletions identified in humans are flanked by short directly repeated sequences; however, mechanisms by which these deletions arise are unknown. A limitation in deciphering these mechanisms is the essential nature of the mitochondrial genome in most living cells. One exception is budding yeast, which are facultative anaerobes and one of the few organisms for which directed mtDNA manipulation is possible. Using this model system, we have developed a system to simultaneously monitor spontaneous direct-repeat–mediated deletions (DRMDs) in the nuclear and mitochondrial genomes. In addition, the mitochondrial DRMD reporter contains a unique KpnI restriction endonuclease recognition site that is not present in otherwise wild-type (WT) mtDNA. We have expressed KpnI fused to a mitochondrial localization signal to induce a specific mitochondrial double-strand break (mtDSB). Here we report that loss of the MRX (Mre11p, Rad50p, Xrs2p) and Ku70/80 (Ku70p, Ku80p) complexes significantly impacts the rate of spontaneous deletion events in mtDNA, and these proteins contribute to the repair of induced mtDSBs. Furthermore, our data support homologous recombination (HR) as the predominant pathway by which mtDNA deletions arise in yeast, and suggest that the MRX and Ku70/80 complexes are partially redundant in mitochondria.
Evaluating Constant Volume Depletion Data
Authors: Whitson Curtis Hays , Torp Stein Børre 
Published: January 2012

ABSTRACT
This paper presents results of analyzing constant volume depletion data obtained from experimental analyses of gas condensates and volatile oils. Theoretical and practical developments are supported by analyses of experimental data from two North Sea condensate reservoirs.
The three major contributions of this work are: (1) presentation of material balance equations used to calculate fluid (particularly liquid) properties from measured constant volume depletion data, (2) a simple method for calculating "black oil" formation volume factors and solution gas-oil ratios for volatile systems using material balance results and a separator flash program, and (3) investigation of the Peng-Robinson equation of state as a tool for matching measured PVT data and studying vapor-liquid equilibria phenomena during constant volume depletion.
The main example presented is a rich gas condensate whose measured, calculated and simulated phase behavior are fully documented in tables and figures. Complete description of the heptanes-plus fraction is also included so that other engineers can check, modify and hopefully improve fluid characterization using the Peng-Robinson (or any other) equation of state.
Challenges and Solutions in Global-Flow-Based Scaleup of Permeability: Isolated Flow Bodies
Authors: Stone Matthew T. , Wu Xiao-Hui , Parashkevov Rossen R. , Lyons Stephen L. 
Published: January 2012

Abstract
One of the unresolved issues preventing the practical application of a flow based global upscaling of permeability is the problem of isolated flow bodies. Isolated flow bodies make a global flow difficult to define in these regions. New and innovative techniques to calculate flow in these regions and how to imbed these solutions into a global upscaling framework are discussed. Specifically, answers to questions of how to apply boundary conditions to isolated bodies and how to handle the barriers are presented. Resolving the issue of isolated flow bodies is a necessary and significant step to enabling global upscaling on a more widespread basis.
The proposed techniques have been applied to several models, demonstrating the capability to use these methods in a global upscaling framework. Together these methods allow the application of global upscaling to a greater variety of geologic model types, enabling the application of global upscaling in situations not previously possible.
Examples of the application of the method show that global upscaling is feasible and provides advantages over industry standard local upscaling methods. Different global upscaling techniques show different behavior on certain model types. The advantages and disadvantages for each technique when applied to different types of models are discussed.
A New Multipoint Flux Approximation for Reservoir Simulation
Authors: Chen Qian-Yong , Wan Jing , Yang Yahan , Mifflin Rick T. 
Published: January 2012

Abstract
Multi-point flux approximations (MPFAs) have been developed in recent years to improve the accuracy of the flux computation for reservoir simulation when the reservoir grids are not K-orthogonal. Recent studies, however, have shown that commonly used MPFA approaches could pose severe limitations. Specifically, it has been observed that MPFA can cause severe nonphysical oscillations in numerical solutions for the single-phase pressure equation if the permeability field is strongly anisotropic. Some researchers have linked those numerical oscillations to the lack of monotonicity in the solution matrix for the discretization problem and efforts have been made to improve MPFA so that matrix monotonicity can be restored.
This paper will present new techniques, collectively called enriched multi-point flux approximations (EMPFAs), to reduce or eliminate numerical oscillations in the solutions. The key to improving the consistency and accuracy of the local flux calculations is the introduction of new temporary unknowns and the application of better pressure interpolation techniques. EMPFA can be used for modeling general multiphase flows in 2-dimensional or 3-dimensional reservoir models, and the grid can be Cartesian, Voronoi, or even arbitrary. Simulation results will demonstrate the differences among EMPFA, MPFA, and the original two-point flux approximation (TPFA).
Unique Solution for Fracture Isolation Resolves Breakthrough Challenges in Horizontal Slim Hole Well
Authors: Al-Mumen Adib A. , Al-Umran Mohammed I. , Agrawal Pradeep , Jorgensen Thomas , Smith Peter E. 
Published: January 2012

Abstract
A mature well in a carbonate reservoir in Saudi Arabia was no longer producing and was sidetracked in a workover operation to regain production. This paper describes the usage of swellable packers to isolate a detrimentally water producing fracture encountered during drilling of a 3-7/8" slim hole horizontal in a naturally fractured carbonate reservoir. No means of open hole/slim hole isolation were available prior to the introduction of swellable packers. The packers were successfully run and the well was brought into production at good rates and low water cut.
Offshore Benign Water-Based Drilling Fluid can Prevent Hard Brittle Shale Hydration and Maintain Borehole Stability
Authors: Peng Chunyao , Feng Wenqiang , Yan Xiaolin , Yan Jienian , Luo Xiangdong 
Published: January 2012

Abstract
In the South West of Weizhou Island, a region of growing importance in oil and gas production in South China Sea, drilling delays and suspension of wells prior to reaching the targets due to wellbore instability, have occurred frequently. The hard brittle shales rich in the formation play the key problematic role. As a result, economic benefits through the use of new drilling technologies are significantly reduced due to high additional drilling costs.
Conventional water-based drilling fluids didn't conquer the problematic formation. They can not prevent filtration from invading formation effectively, thereby the shale hydration and prore pressure increase can not be eliminated. Alternatively, oil-based drilling fluids can provide superb borehole stability. Especially formulated with the efficient sealing materials, they can be available in drilling the hard brittle shale formation. It had been proven by some successful cases in the South West of Weizhou Oilfield. However, the employment of oil-based drilling fluids is cause for increasing concern due to offshore environmental restrictions and expensive disposal costs.
An environmentally acceptable water-based drilling fluid, which is based on methylglucoside and silicate, is developed to conquer the hard brittle shale formation. It has been confirmed from numerous laboratory results that the MS drilling fluid exhibited perfect filtration loss control and inhibitive abilities and also can effectively seal microfractures by physical packing and chemical precipitation. It stabilizes the hard brittle shale by the same mechanism as did oil-based drilling fluid in preventing shale hydration, pore pressure increase and weakening of shale by effectively developing sufficient osmotic force to offset hydraulic and chemical forces acting to cause filtration flux into the hard brittle shale.
MS drilling fluid has given its first offshore field trial in Weizhou oilfield. The data from the pilot well has showed that the novel drilling fluid exhibited excellent inhibition and lubricity which approaches or even exceeds oil-based fluids.
Through-Tubing Casing Exit and Inflatable Technologies Combine to Deliver Enhanced Production during Coiled Tubing Drilling Campaign in the Middle East
Authors: Garfield Garry 
Published: January 2012

Abstract
As part of a coiled tubing drilling re-entry campaign for a client in the Middle East, a well required a through-tubing casing exit system to enable the subsequent drilling assembly access to drill a new lateral. On completion of the drilling phase, a production well test determined that water production from the lower perforations in the main bore had increased to an unacceptable limit, and a water shut-off solution was required.
The paper will provide a comprehensive overview of utilizing a through-tubing whipstock system deployed with coiled tubing in order to create an effective window in the production liner. One of the major advantages of a coiled tubing deployed exit system is the ability to mill a window in the casing in a restricted wellbore environment. The whipstock can be deployed into a live-well environment without the necessity of removing the completion equipment, thus eliminating the requirement for a workover rig or potentially reservoir-damaging well kill fluids. The paper will also focus on the use of through-tubing inflatable technology and the relationship of utilizing these unique devices for water shut-off applications.
The case history will detail the running of a new exit system showing the economic benefits of utilizing live well intervention deployment methods for whipstock placement as well as the rig cost savings of utilizing coiled tubing deployed mills and motors for delivering a casing window. The case history will also detail inflatable technology for water shut off applications for this particular well focusing on the ability to run and set the inflatable device in a cross-flow environment.
Dynamic Formations Rendered Less Problematic with Solid Expandable Technology
Authors: Jennings Iain 
Published: January 2012

Abstract
To reach drilling objectives in dynamic formations requires robust technology that can adapt to unpredictable wellbore conditions. Such is the case with operations in Asia Pacific; a very tectonically active region. The shifting plates put the earth's crust under extreme stress, which has a propensity to cause various difficult drilling conditions including: FaultsHigh pore pressureWellbore instability
These issues are difficult to predict, both in occurrence and true vertical depth (TVD), and are usually mitigated by running an unplanned string of casing. Unexpected conditions requiring a casing point put the drilling plan at risk when reservoir objectives are hole-size dependent. Standard oil country tubular goods (OCTG) reduce the wellbore inside diameter (ID) every time a casing string is set. When the situation dictates setting casing higher than planned, solid expandable technology has successfully minimized wellbore reduction and enabled the operator to get back to the casing program with an optimized hole size.
Planning solid expandable systems into wellbore construction as a design element, rather than a contingency plan, has averted numerous problems identified during the drilling process.
Conventional solid expandable systems minimize loss of hole size, while single-diameter expandable systems (including openhole cladding) provide solutions without loss of hole size. By utilizing single-diameter technology, zones and formations can be sealed, allowing the next hole section to be drilled with the same bit as the previous. In this capacity, expandable systems become an enabling technology for previously undrillable wells.
This paper will discuss how solid expandable tubular systems have evolved to include a technology suite of options that addresses drilling challenges in active formations. Case histories will be used to illustrate the technical and economic value brought to projects by way of solid expandable system application.
Cost Evaluation for the First Running Experience of Expandable Openhole Liner for Unexpected Problems in Drilling Well, Iran
Authors: Yousafi Y. , Fazaelizadeh M. , Hareland G. , kustamsi A. , Mirhaj S. A. , Shirkavand F. 
Published: January 2012

Abstract
The expandable openhole liner system is used as solution for operational challenges associated with borehole instabilities, pore pressure/fracture gradient issues and the effect of salt or subsalt formation. All these operational challenges produce pre- mature downsizing of well's tubular.
While drilling in the Kupal oilfield located in south west of Ahwaz, Iran, an isolated extreme thief zone was penetrated resulting in a possible unplanned conventional liner was run, decreasing further deeper hole sizes. The smaller size of liner would have cause problems such as lower reservoir production rate and putting limitations on running measurement tools to evaluate the reservoir. Because of these aforementioned negative effects of running a conventional liner it was instead desided to run an expandable openhole liner.
This paper discusses challenges and solutions for running the first expandable openhole liner in Iran to reach a proposed target with the planned hole sizes as well as a cost evaluation and comparison of two wells, one using expandable open hole liner and one using conventional liner.
A Simple Analytical Model for Vertical Permeability Prediction (Alternate Title: Modelling vertical permeability at microscopic and reservoir scales)
Authors: Uguru C. I. , Onyeagoro U. O. , Onuoha K. M. 
Published: January 2012

Abstract
With reservoir management leaning increasingly on numerical simulation, adequate reservoir characterization is critical to the process of developing good reservoir models that can be used to predict reservoir performance. Previously vertical permeability for reservoirs was modelled based on facies/genetic unit averages of kv/kh (vertical permeability to horizontal permeability) ratios. This method does not account for reservoir heterogeneity. Additionally, this averaging method has been found to be quite sub-optimal because the wide range of the values for kv/kh ratios for any genetic unit makes representation by a single average value grossly inadequate. In the quest for improved reservoir characterization an analytical model for predicting vertical permeability has been developed and is discussed in this paper. The model is based on the architecture of reservoirs, core data from the Niger Delta, the laws for permeability averaging and elementary differential calculus. With the proposed model continuous property curves for vertical permeability that account for reservoir heterogeneity can be generated for any reservoir interval of interest. This was hitherto not possible with the previous techniques. Comparisons of modelled vertical permeability profiles with real data show excellent agreement and indicate that the proposed model adds reasonable value to the effort to describe reservoirs better. Having matched core data on vertical permeability a "tuning" scheme based on outcrop analogues and log character is proposed for modeling vertical permeability on a reservoir scale. The advice of this paper is not to focus on devising an appropriate permeability averaging technique but on the reservoir character that will dominate fluid flow under the influence of a pressure gradient.
Optimization of Behind Casing Resistivity Analysis Using Nuclear Logs
Authors: Akem Benjamin , Anyaehie James , Arogun Olubunmi , Abangwu Prince 
Published: January 2012

Abstract
Conventional resistivity analysis has been used for evaluation of hydrocarbon saturation in both exploratory and development wells. Resistivity logs are however not sufficient for performance of a fluid characterization because resistivity cannot detect variation in hydrocarbon densities. As a result, additional logs such as nuclear, sonic and nuclear magnetic resonance logs are required to perform a satisfactory evaluation of hydrocarbon fluid typing and saturation computation.
This paper focuses on recommended best practices for combination of behind casing resistivity measurements and complementary logs in matured fields for evaluation of hydrocarbon/water contacts, detection of by-passed reserves and fluid typing.
An example from the eastern Niger Delta shows where cased hole formation resistivity results were optimized with pulsed neutron spectroscopy measurements in performing a successful workover program and improving production rates by over 80%
Upscaling Local CO2 Trapping During Buoyancy-Driven Flow
Authors: Saadatpoor Ehsan , Bryant Steven L. , Sepehrnoori Kamy 
Published: January 2012

Abstract
Assessment of storage capacity of a formation and the risk involved in using that capacity are essential tasks for large scale carbon sequestration. Simulations are useful tools for this purpose, but some modes of trapping that reduce risk present challenges for simulators. One of these modes is local capillary trapping, which occurs during buoyancy-driven flow through rocks with fine-scale heterogeneity. However, fine-scale simulation is always costly or even impractical, and an accurate upscaling method would greatly facilitate assessment of large fields nominated for storage. This application is a useful example in the science of upscaling of a flow process in which the displacement physics are tightly coupled to the rock heterogeneity.
We examine the basis for upscaling local capillary trapping for practical coarse-grid simulations. We carry out a series of full-physics simulations of buoyancy-driven migration of CO2 within heterogeneous aquifers. The simulations include studies of a leak appearing in the top seal after buoyant migration has ended. The effect of heterogeneity enters via scaled capillary pressure curves for all grid blocks. We vary the degree of coarsening and compare the distribution of CO2 into different storage modes for each simulation. Preferential flow paths, which contain CO2 trapped at saturations far above core-scale residual, exhibit structures several times larger than the correlation length of the permeability field. A coarse-grid simulation that only upscales heterogeneity is inaccurate to capture this behavior. Hence, we use simulations and post process the data to compute a new parameter called effective residual saturation for the whole aquifer domain. A linear relationship is shown to exist between effective maximum residual gas saturation and mass of CO2 escaped through leaks. The relationship holds for grid blocks larger than the correlation lengths of permeability field and entry pressure field.
Fracture Mechanics Interpretation of Leak-Off Tests
Authors: Aadnoy Bernt S. , Mostafavi Vahid , Hareland Geir 
Published: January 2012

Abstract
This paper presents a model for leak-off interpretation that includes evaluation after the borehole is fractured. The Kirsch equation is valid up to the conventional leak-off point, but beyond leak-off the hole is fractured, and an elastoplastic bridge model applies to ultimate failure. Also presented is an evaluation of in-situ stress interpretations from leak-off tests.
Findings of the new model are that the leak-off point using Kirsch is correctly defined by the in-situ stress state and the rock tensile strength. The model also explains the circulation loss problem with oil based drilling fluids where the wellbore strength reduces to the minimum horizontal stress level.