bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absence of Lateral Composition Fluctuations in Aberration-corrected STEM Images of an InGaN Quantum Well at Low Dose
Authors: Yankovich Andrew B. , Kvit A. V. , Li X. , Zhang F. , Avrutin V. , Liu H.Y. , Izyumskaya N. , Özgür Ü. , Morkoç H. , Voyles P. M. 
Published: October 2012

ABSTRACTBy using aberration corrected scanning transmission electron microscopy we have found no small scale lateral In composition fluctuations exist in the In0.15Ga0.85N active region of a light emitting diode. Images were acquired at 2% of the electron dose known to create electron beam damage, so the acquired images reflect the intrinsic structure of the InGaN active region. Position averaged convergent beam electron diffraction reveals the local sample thickness where images were acquired is 4.8 nm, eliminating the possibility that the absence of composition variation was observed due to projection through a thick sample. In addition, 2-3 atomic layer steps were observed in the top surface of In0.08Ga0.92N layers and the In0.15Ga0.85N active layers, providing a possible mechanism for lateral carrier confinement.
Characterization of rf-sputtered HfMgZnO thin films
Authors: Chung Hantsun , Chen Jian-Zhang , Cheng I-Chun 
Published: October 2012

ABSTRACTMgZnO becomes amorphous or short-range-ordered with the addition of hafnium oxide. The films are rf-sputter deposited onto glass substrates (Eagle 2000, Corning Inc.) from Mg0.05HfxZn0.95-xO targets (x=0, 0.025, 0.05, 0.075, 0.1) in pure Ar ambient at room temperature. The sputtered Mg0.05Zn0.95O exhibits strong (002) preferred orientation with XRD peak located at 2θ=34.16o. The XRD peak intensity is also greatly reduced, indicating the material amorphorization proceeds with the addition of Hf. The grain size, estimated from the full-width-at-half-maximum (FWHM) of the (002) XRD peak, decreases from 24.1 to 3.3 nm as the Hf content x increases from 0 to 0.025 in Mg0.05HfxZn0.95-xO. No sharp XRD peaks are detected in the as-sputtered films when more than 5.0 at.% Hf are added into the materials. The films remain in amorphous or short-range-ordered states after annealing at 600 oC for 30 mins. All Mg0.05HfxZn0.95-xO films (100 nm in thickness) are highly transparent (> 80 %) in the visible region from 400 to 800 nm and have sharp absorption edges in the UV region. The tauc bandgap ΔE (eV), as a function of hafnium composition x, is fitted as ΔE=3.336+6.08x for room temperature as-deposited films, and ΔE=3.302+2.60x for films after 30 min 600 oC annealing. The annealing process decreases the bandgap shift caused by the incorporation of Hf in the materials.
Analysis of Production Decline Characteristics of a Multi-Stage Hydraulically Fractured Horizontal Well in a Naturally Fractured Reservoir
Authors: Ketineni Sarath Pavan , Ertekin Turgay 
Published: October 2012

Abstract
Most unconventional gas reservoirs are naturally fractured in nature and exhibit dual porosity characteristics. Hydraulic fracturing often alters the reservoir parameters around the wellbore, thus, potentially creating a rubble zone (stimulated reservoir volume-SRV) with distinctly different characteristics when compared to the outer zone. This problem could ideally be approximated as an equivalent flow problem around a horizontal wellbore in a composite naturally fractured domain.
The computational package developed in the current study could be used in generating forward solutions for prediction of production transients in hydraulically fractured double porosity reservoirs. Additionally, as a part of an inverse analysis procedure, using relevant dimensionless parameters, it will be possible to characterize the composite naturally fractured reservoirs.
A solution to the elliptical flow problem that considers flow into a horizontal wellbore in a truly composite naturally fractured reservoir has been attempted. Mathieu modified functions were used to solve the elliptical flow problem. Stehfest algorithm is used for inversion of the Laplace space solutions back to real time domain. This generated solution is validated with other existing solutions by collapsing it into its subsets given in the literature. Forward solutions are generated for various dimensionless parameters. A graphic user interface (GUI) has been developed to generate production decline curves.
The interface elliptical coordinate does have a significant effect on the dual porosity signature of production transients in the case of mobility ratios higher than 10. It is observed that the mobility ratio, diffusivity ratio, storativity ratio, interporosity flow coefficient ratios of the inner, and outer regions exhibit significant effects on the decline curves experienced by this class of reservoirs.
Methodology for Analytic Estimation of Fast Shear Polarization Direction in HTI Formations
Authors: Collins Mark 
Published: October 2012

Abstract
A new algorithm for processing cross-dipole acoustic log waveforms in formations with horizontal transverse anisotropy (HTI) has been developed. Conventional algorithms for anisotropy processing of cross-dipole acoustic waveforms minimize an objective function whose parameters are the azimuth angle of a reference (usually X-dipole) transmitter relative to the fast principal flexural-wave axis of the HTI formation and the fast and slow shear wave slowness. Minimizing the objective function with respect to all the parameters provides the desired anisotropy angle and the amount of anisotropy. It is common to minimize the objective function over all the parameters using a numerical search method (such as very fast simulated annealing) or by evaluating the objective function on a fine grid in the parameter space (i.e., brute force); however, this is never necessary with cross-dipole waveforms. It is possible to derive equations for the angle of the X-dipole relative to the fast principal flexural-wave axis that can be solved analytically as a function of the other parameters.
Analytic computation relative to numerical computation provides several advantages. First, the angle found at any given point in the auxiliary parameter space is a mathematically exact global minimum (up to computer precision) with respect to the angle of the objective function at that point in the auxiliary parameter space. This is not guaranteed with a numerical-search algorithm. In addition, studying the objective function at the minimizing angle with respect to the remaining auxiliary parameters can provide insight as to the best means of minimizing the objective function with respect to the remaining parameters. This paper uses synthetic and field data to demonstrate the advantages of this new algorithm.
Improved Time-Based Processing of Broadband Borehole Acoustic Data Using Delay Filters
Authors: Donderici Burkay , Tracadas Philip 
Published: October 2012

Abstract
Borehole acoustic tools that use broadband source excitation functions can optimally excite multiple frequencies at nearly the same time, yielding a wide range of different formation acoustic response properties in the received signal. However, the analysis of received broadband signals is not straightforward in the time-domain because standard time semblance algorithms suffer from interference when received acoustic modes with different slownesses and frequency content arrive at a similar time. Another method, frequency semblance, is computationally expensive and is sensitive to noise and to other effects. We propose using specially designed phase filters that can move (delay) individual frequency contributions differently in time without changing the spectral amplitudes of the received signal, thus enabling existing time semblance methods to perform optimally at many frequencies by separating the received spectra in time.
Predicting Pyrite and Total Organic Carbon from Well Logs for Enhancing Shale Reservoir Interpretation
Authors: Witkowsky Jim , Galford James , Quirein John , Truax Jerome 
Published: October 2012

Abstract
Accurate quantification of total organic carbon (TOC) is an important step in evaluating log data in organic-rich reservoirs. The literature describes many log-based approaches for predicting TOC that have been introduced over the years, including the use of uranium content or GR linear regression, bulk density, the DeltaLogR approach, neural network approach, and a response equation-based method using sonic, density, and resistivity logs. All of the approaches require core-to-log calibration for validation. Each of these techniques involves assumptions for them to be valid, and, in a given instance, it is possible some techniques will not produce reliable results. However, good log-based TOC quantifications can be achieved by taking the median average of TOC estimates from several indicators.
Many shale reservoirs contain 10 wt% pyrite and total organic carbon (TOC), which translates to 7% pyrite and 20% kerogen by volume. High volumetric percentages of pyrite and kerogen significantly affect the rock grain density. In low-porosity shale reservoirs, each 0.02 g/cm3 error in grain density produces approximately 1 p.u. error in porosity.
Pyrite is commonly present in organic-rich shale intervals of shale gas formations because of the reducing conditions that enhanced organic matter preservation, and it may play a role in decreased resistivity response if the volume is sufficient.
Consequently, in shale reservoirs, any method of predicting TOC using resistivity logs, such as DeltaLogR, should also consider the presence of pyrite. Similarly, TOC predictions based on bulk-density logs may also be sensitive to elevated pyrite concentrations.
The link between pyrite presence and the depositional environment for many organic-rich shale reservoirs suggests that pyrite and sulfur may be useful TOC indicators in some situations. This paper examines the possible application of pyrite and sulfur for predicting TOC in shale reservoirs, such as in the Haynesville shale reservoir, but results should be applicable to many other shale reservoirs. An interesting result is that, although it may be possible to calibrate a TOC-based pyrite indicator for individual wells, the calibration is not universally applicable.
Modeling and History Matching of Hydrocarbon Production from Marcellus Shale using Data Mining and Pattern Recognition Technologies
Authors: Esmaili S. , Kalantari-Dahaghi A. , Mohaghegh S. D. 
Published: October 2012

Abstract
The Marcellus Shale play has attracted much attention in recent years. Our full understanding of the complexities of the flow mechanism in matrix, sorption process and flow behavior in complex fracture system (natural and hydraulic) still has a long way to go in this prolific and hydrocarbon rich formation.
In this paper, we present and discuss a novel approach to modeling and history matching of hydrocarbon production from a Marcellus shale asset in southwestern Pennsylvania using advanced data mining & pattern recognition technologies. In this new approach instead of imposing our understanding of the flow mechanism, the impact of multi-stage hydraulic fractures, and the production process on the reservoir model, we allow the production history, well log, and hydraulic fracturing data to force their will on our model and determine its behavior. The uniqueness of this technique is that it incorporates the so-called "hard data" directly into the reservoir model, such that the model can be used to optimize the hydraulic fracture process. The "hard data" refers to field measurements during the hydraulic fracturing process such as fluid and proppant type and amount, injection pressure and rate as well as proppant concentration.
The study focuses on part of Marcellus shale including 135 wells with multiple pads, different landing targets, well length and reservoir properties. The full-field history matching process was completed successfully. Artificial Intelligence (AI)-based model proved its capability in capturing the production behavior with acceptable accuracy for individual wells and for the entire field.
Permeability and Completion Efficiency Determination From Production Data in the Haynesville, Eagle Ford, and Avalon Shales
Authors: Rodrigues E. , Callard J. 
Published: October 2012

Abstract
Production analysis can aid in the determination of formation and stimulation characteristics including permeability, fracture half length, fracture conductivity, and completion efficiency. The time to the end of the infinite acting linear flow combined with the distance between stimulated fracture faces yields permeability. The production analysis method includes three flow regimes; infinite acting linear flow, fracture-fracture interference from evenly spaced fracture stimulation treatments which leads to boundary dominated flow and fracture-fracture interference when fracture stimulation treatments are unevenly spaced.
Production for the uneven or non-uniform spacing situation can provide perforation cluster completion efficiency for plug and perf completions and can be diagnostic in packer ports systems when stimulations are originated at the packer due to packer induced rock failure.
Low completion efficiencies could dictate fewer clusters per stage in future designs. If low completion efficiencies are revealed, increased isolation to maintain actual stimulated fracture face distance may be required. In packer port systems identification of non-design uneven spacing may also warrant increased isolation.
Case studies from three shale reservoirs are included to illustrate the production analysis techniques.
Using Multiple Linear Regression to Model EURs of Horizontal Marcellus Shale Wells
Authors: Cunningham Charles F. , Cooley Lisa , Wozniak Gregory , Pancake Jim 
Published: October 2012

Abstract
EQT Production has been actively drilling the Marcellus Shale in Pennsylvania and West Virginia since 2008. With over 170 producing horizontal wells in the Marcellus, EQT has a significant data set for evaluation using Multiple Linear Regression. A variety of well design parameters can be compared to production in hopes of finding a correlation and identifying what determines a well’s Estimated Ultimate Recovery (EUR). Some of the most logical parameters to compare include lateral length, lateral azimuth, formation target, formation mineralology and stimulation design. Multiple Linear Regression is a powerful tool for bringing many of these design aspects together for comparison against productivity and can reveal patterns and relationships that may be indiscernible using conventional methods.
A regression software package was used for this study following the Least Squares method. Well EUR was the primary dependent variable throughout the analysis. Each individual dataset consists of wells in close proximity to one another (map quad, county, etc.). Dozens of drilling and completion parameters were compared against the EURs, as independent variables. Multiple iterations of removing and adding specific independent variables led to an optimal EUR model for a particular area.
Four main areas were the focus for the study, and the results have been conclusive. In all areas, treated lateral length exhibited a near-linear relationship with EUR. More specifically, in Area 1, the model exhibited an R-Squared value of 0.97. This was achieved using only three independent variables: treated lateral length, perforation cluster spacing, and lateral spacing. Realistic models were built, with conclusive results, in Areas 2, 3, and 4 using different criteria. Multiple Linear Regression Models can provide extremely important information for field development. Using MLR models, coefficients are obtained for each of the independent variables (i.e. the quantitative effect each parameter has on a well’s EUR). These values can be extended to new areas, and a more accurate EUR can be predicted, often before the well is drilled. In core areas, when an operator is forced to make decisions based on land and drilling constraints, this method can be used to make the best economic decision for drilling and completion design.
A New Simulation-Based Process to Predict the Impact of Hydraulic Fracture Parameters on EUR: A Tight Gas Field Example
Authors: Yetkin C. , Firincioglu T. , Haney A. M. 
Published: October 2012

Abstract
This study develops a process that determines the critical hydraulic fracture parameters and quantifies their impact on the EUR by combining reservoir simulation with probabilistic analysis methods. The process is verified by a real field case example in a tight gas reservoir. The final product can be applied to other unconventional reservoirs to ultimately maximize revenues by planning superior fracturing operations and optimizing well spacing.
A detailed dual porosity, 1 section reservoir model was created and history matched to model the flow mechanism. A fine layered (2-3ft) geostatistical model was utilized in simulation without upscaling. The dual porosity formulation enabled the simulation model to represent the hydraulic fracture - matrix interaction properly so that the flowback and formation water production could be matched also.
During the history matching phase, the parameters that control the impact of hydraulic fractures on the recovery were identified as follows:Matrix-fracture exchange: this parameter represents the complexity of the fractures and is controlled by the surface area created during hydraulic fracturing.Fracture conductivity: this is effectively the permeability of the hydraulic fractureHalf length: this parameter impacts the extent of the hydraulic fracture, therefore the amount of matrix that has been accessed.Job size: The size of the frac fluid volume injected during the hydraulic fracturing process
In this work, an internal proprietary technology that creates a response surface for the combination of the parameters defined above was utilized. This technology utilizes Experimental Design, Response Surfaces and Constrained Monte Carlo. The history matched simulation model was automatically modified to create the necessary cases to calculate a multi-dimensional response surface. The created response surface was then used to do Monte Carlo simulations to create P10 to P90 probabilities of the total gas production (EUR).
The results of the study allowed us to understand not only the mechanisms operating in the reservoir being studied, but also the required hydraulic fracture parameters (ranges) to achieve a given EUR of a specific probability. The same algorithms were then be used to predict the future performance of other well spacing patterns and hydraulic fracture job sizes.
New Slurry Design Concepts Using Multifunctional Additives to Improve Quality and Sustainability of Cementing Systems for Zonal Isolation
Authors: Brandl A. , Narvaez G. G. , Bray W. S. 
Published: October 2012

Abstract
The benefits of a new class of a multifunctional cement additive and the performance of the resulting cementing systems are evaluated in comparison to conventional slurry designs used for cementing wells in the Northeastern U.S. Cement testing procedures, lab test results, logistical and operational aspects, economical and ecological balances, chemical footprints of slurry designs are presented and discussed. The tested multifunctional additive can fully replace at least 4 different additives (extender, suspending agent, free fluid, fluid loss, and gas control additive) to achieve the desired performances and so simplify cement slurry designs. The multifunctional additive in this study also exhibits delayed hydration, which facilitates surface mixing and generates desired high viscosity over time, minimizing settling issues in horizontal wells during placement. The innovative cement design concept using a multifunctional additive reduce the number and loadings of chemical additives required to adjust the performance of cement slurries, thereby improving economics, reducing the chemical footprint, and simplifying logistics and operations.
How Much Does IFRS Cost? IFRS Adoption and Audit Fees
Authors: De George Emmanuel T. , Ferguson Colin B. , Spear Nasser A. 
Published: October 2012

ABSTRACT
This study provides evidence of a directly observable and significant cost of International Financial Reporting Standards (IFRS) adoption, by examining the fees incurred by firms for the statutory audit of their financial statements at the time of transition. Using a comprehensive dataset of all publicly traded Australian companies, we quantify an economy-wide increase in the mean level of audit costs of 23 percent in the year of IFRS transition. We estimate an abnormal IFRS-related increase in audit costs in excess of 8 percent, beyond the normal yearly fee increases in the pre-IFRS period. Further analysis provides evidence that small firms incur disproportionately higher IFRS-related audit fees. We then survey auditors to construct a firm-specific measure of IFRS audit complexity. Empirical findings suggest that firms with greater exposure to audit complexity exhibit greater increases in compliance costs for the transition to IFRS. Given the renewed debate about whether the Securities and Exchange Commission (SEC) should mandate IFRS for U.S. firms, our results are of timely importance.
Data Availability: Data are publicly available from the sources identified in the paper. Survey response data are available from the authors upon request.
Effects of mechanical properties of thermoplastic materials on the initial force of thermoplastic appliances
Authors: Kohda Naohisa , Iijima Masahiro , Muguruma Takeshi , Brantley William A. , Ahluwalia Karamdeep S. , Mizoguchi Itaru 
Published: October 2012

ABSTRACT

Objective:
To measure the forces delivered by thermoplastic appliances made from three materials and investigate effects of mechanical properties, material thickness, and amount of activation on orthodontic forces.

Materials and Methods:
Three thermoplastic materials, Duran (Scheu Dental), Erkodur (Erkodent Erich Kopp GmbH), and Hardcast (Scheu Dental), with two different thicknesses were selected. Values of elastic modulus and hardness were obtained from nanoindentation measurements at 28°C. A custom-fabricated system with a force sensor was employed to obtain measurements of in vitro force delivered by the thermoplastic appliances for 0.5-mm and 1.0-mm activation for bodily tooth movement. Experimental results were subjected to several statistical analyses.

Results:
Hardcast had significantly lower elastic modulus and hardness than Duran and Erkodur, whose properties were not significantly different. Appliances fabricated from thicker material (0.75 mm or 0.8 mm) always produced significantly greater force than those fabricated from thinner material (0.4 mm or 0.5 mm). Appliances with 1.0-mm activation produced significantly lower force than those with 0.5-mm activation, except for 0.4-mm thick Hardcast appliances. A strong correlation was found between mechanical properties of the thermoplastic materials and force produced by the appliances.

Conclusions:
Orthodontic forces delivered by thermoplastic appliances depend on the material, thickness, and amount of activation. Mechanical properties of the polymers obtained by nanoindentation testing are predictive of force delivery by these appliances.