bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fracture and Wellbore Spacing Optimization in Multistage Fractured Horizontal Wellbores: Learnings from Our Experience on Canadian Unconventional Resources
Authors: Ziarani Ali S. , Chen Cheney , Cui Albert , Quirk David James , Roney Dana 
Published: May 2016

Abstract
Horizontal wellbore drilling and completion technology with multi-stage fracturing has revolutionized the exploitation of unconventional resources in North America in recent years. Many unconventional oil and gas reservoirs with ultra-low permeability have become economical as a result. Yet, the development and completion costs of these resources can be further improved by optimizing the number of fracture stages placed on each wellbore and the number of wellbores drilled per section of land.
This study highlights our operational and analytical experience on an integrated workflow for optimization of fracture and wellbore spacing to develop the unconventional resource in Western Canadian Sedimentary Basin. The study is based on fracturing design and optimization, microseismic fracture mapping, reservoir modeling and production analysis for over 30 case studies on different formations in Canada including Montney, Cardium, Doig, Beaverhill Lake, Viking, and Sprit River formations.
The typical workflow for fracture and well spacing optimization studies includes multiple and iterative steps: minifrac tests, fracture modeling and calibration, fracture job execution, microseismic monitoring, reservoir simulation and production data analysis. In this integrated process, hydraulic fracture models were built based on fracture job data, rock mechanics and log data, and then calibrated with minifrac data and microseismic fracture mapping results. Three dimensional reservoir simulation models were constructed using laboratory core data, petrophysical and geological data, and reservoir fluid PVT properties. The calibrated fracture models were integrated into reservoir simulation models. The reservoir models were fine-tuned by history matching the production data. The fine-tuned models were then used to run multiple scenarios by varying the number of fracturing stages per wellbore and wellbores per section. Fracturing treatments with different pump rate, proppant size, pumping schedule and proppant tonnage were further investigated to optimize fracture geometry and conductivity for production enhancement. Optimal fracture and wellbore spacing scenarios were recommended for future drilling and completion planning in the field.
Such optimization studies have helped to minimize operation cost and improve the economics of resource development. Our workflow and experience in West Western Canadian Sedimentary Basin can be a useful guideline to improve economic success of unconventional resources in other basins around the world.
Recent Hydrocarbon Discovery in Pre-Carbonate Clastic Reservoir: Unlocking Deeper Potential in Sarawak Offshore!
Authors: Ali Mohd Firdaus , Nayak Satyabrata , Abd Aziz Anuar , Amir Khan Noorshireen , Zainun Fakhitah , Tukimin Nurmaliza 
Published: May 2016

Abstract
A recent Oil and Gas discovery in an exploratory well in the Balingian Province could be the prelude to a new era of hydrocarbon exploration in deeper stratigraphy (Cycle-I) of the Sarawak offshore. In spite of various hydrocarbon discoveries made previously, only few wells flowed naturally from Cycle-I due to low permeability. Hence, natural oil flow during a DST from the well is a first of its kind in the block and nearby area. With limited data, few well penetrations and poor seismic data quality, Cycle-I exploration remains challenging and less understood. Hence the success is more of a "challenge" to "cherish" story. An extensive regional study, including preparation of time/depth structure maps, regional isopach maps, well penetration charts, play fairway maps and post drill analyses (PDA) of available wells was carried out for the prospect de-risking. Poor seismic data (mainly due to lower frequency in deeper section and shallow gas clouds overlying the objective at the well location) and the uncertainty of reservoir quality (low permeability) observed in the block become the major challenges in finding the best spot to test hydrocarbon prospectivity of Cycle-I. Despite of being low permeability, the reservoir of Cycle-I sand flowed around 400–500 bopd. This flow rate is significant as this is the first recorded data that the Cycle-I reservoir has been production tested in the block and nearby area. Usage of a robust workflow, state-of-art software and cutting edge technology contributed to the success in this well. Apart from various technical studies carried out during the project, the decisive factor behind the success of the well is the "explorer mindset" of the team and full support from the management. The discovery has wider implications for the hydrocarbon exploration of the deeper stratigraphy in this mature basin.

Introduction
The study area is a part of the Balingian Province, which historically has been a prospective area for oil and gas exploration in offshore Sarawak, Malaysia (figure 1). A number of exploration wells have been drilled in the region by various operators since 1970's. Almost without exception, the primary objective was to test hydrocarbon prospectivity of Carbonate and Pre-Carbonate plays. Although hydrocarbon discoveries were made in Pre-Carbonate of Cycle-II and Cycle-III reservoirs, Cycle-I has remained poorly explored till date. With only few well penetrations, limited data, poor – moderate seismic quality, Cycle-I exploration remains challenging and little understood. In February 2013, PCSB took a step further to drill well S1 targeting for Pre-Carbonate reservoirs of Cycle-II and Cycle-I in a faulted anticline. Well S1 well could successfully flow oil naturally from Cycle-I reservoir without any stimulation. The oil discovery in Pre-Carbonate of Cycle-I is significant and key for future exploration of Pre-Carbonate plays.
Risk of Peritoneal Dialysis-Related Peritonitis in a Multi-Racial Asian Population
Authors: Ong Loke Meng , Ch'ng Chin Chin , Wee Hong Chin , Supramaniam Premaa , Zainal Hadzlinda , Goh Bak Leong , Bavanandan Sunita , Mushahar Lily , Hooi Lai Seong , Ahmad Ghazali 
Published: May 2016

Background Peritonitis is one of the most common complications of peritoneal dialysis (PD). Understanding the risk factors of peritonitis in a multi-racial Asian population may help to improve outcomes on PD. Methods We conducted a prospective observational study to identify risk factors for PD-related peritonitis over a 1-year period in 15 adult PD centers. All peritonitis episodes were independently adjudicated. Results A total of 1,603 participants with a mean age of 51.6 years comprising 52.7% females, 62.6% ethnic Malays, 27.0% Chinese, and 8.1% Indians were recruited. The overall peritonitis rate was 1 episode per 44.0 patient-months with 354 episodes recorded in 282 (17.6%) patients over 15,588 patient-months. Significant risk factors of peritonitis were severe obesity (incidence-rate ratio [IRR] 3.32, 95% confidence interval [CI]: 1.30, 8.45), hypoalbuminemia (IRR 1.61, 95% CI: 1.06, 2.46), Staphylococcus aureus nasal carriage (IRR 2.26, 95% CI: 1.46, 3.50), and use of Fresenius system (Fresenius Medical Care North America, Waltham, MA, USA) (IRR 2.49, 95% CI: 1.27, 4.89). The risk of peritonitis was lower in those on automated PD compared with standard PD (IRR 0.43, 95% CI: 0.25, 0.74), and in centers with a patient-staff ratio of 15 to 29.9 (IRR 0.67, 95% CI: 0.49, 0.90) and ≥ 30 (IRR 0.52, 95% CI: 0.34, 0.80). Prevalent patients and exit-site care with topical antibiotics were also protective against peritonitis. Peritonitis rates varied between racial groups. The IRRs of overall peritonitis and gram-positive peritonitis in Chinese versus other racial groups were 0.65 (95% CI: 0.46, 0.90) and 0.47 (95% CI: 0.24, 0.91), respectively. Conclusions Multiple patient, center, and PD-system factors influence the risk of peritonitis. In the Asian population, there are racial differences in the risk of peritonitis.
Risk Factors for Early-Onset Peritonitis in Southern Chinese Peritoneal Dialysis Patients
Authors: Wu Haishan , Huang Rong , Yi Chunyan , Wu Juan , Guo Qunying , Zhou Qian , Yu Xueqing , Yang Xiao 
Published: May 2016

Background Early peritonitis was confirmed to be associated with a higher risk of early technique failure. However, literature concerning peritonitis within the first 3 months of peritoneal dialysis (PD) initiation is scarce. The present study was to investigate risk factors associated with early-onset peritonitis in PD patients. Methods In this retrospective observational cohort study, all incident PD patients from January 1, 2006, to December 31, 2013, were recruited and followed up until December 31, 2014. According to time-to-first episode of peritonitis, patients were divided into early-onset (≤ 3 months) peritonitis and late-onset (> 3 months) peritonitis. Baseline demographic, clinical, and laboratory data, as well as episodes of peritonitis, were collected. Risk factors associated with early-onset peritonitis were evaluated using logistic regression model. Results Of 1,690 patients on PD, 503 (29.8%) developed at least 1 episode of peritonitis and 118 (7.0%) patients presented the first episodes of peritonitis within the first 3 months. A multivariate logistic analysis showed that higher body mass index (BMI) (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.01 – 1.15, p = 0.034), hypoalbuminemia (OR 1.75, 95% CI 1.11 – 2.78, p = 0.017), and catheter exit-site infection (OR 4.14, 95% CI 2.45 – 7.00, p < 0.001) were risk factors independently associated with early-onset peritonitis. Compared to those with late-onset, patients with early-onset peritonitis had a higher overall peritonitis rate (0.76 vs 0.38 per patient-year, p < 0.001) and worse technique survival ( p < 0.001), while patient survival did not differ significantly between the 2 groups during the long-term follow-up ( p > 0.05). Conclusions Higher BMI, hypoalbuminemia, and catheter exit-site infection were the risk factors associated with early-onset peritonitis in PD patients.
New Insights into the Effects of Chronic Kidney Failure and Dialysate Exposure on the Peritoneum
Authors: Vlahu Carmen A. , Aten Jan , de Graaff Marijke , van Veen Henk , Everts Vincent , de Waart Dirk R. , Struijk Dirk G. , Krediet Raymond T. 
Published: May 2016

Introduction Chronic uremia and the exposure to dialysis solutions during peritoneal dialysis (PD) induce peritoneal alterations. Using a long-term peritoneal exposure model, we compared the effects of chronic kidney failure (CKD) itself and exposure to either a ‘conventional’ or a ‘biocompatible’ dialysis solution on peritoneal morphology and function. Methods Wistar rats (Harlan, Zeist, the Netherlands) were grouped into: normal kidney function (NKF), CKD induced by 70% nephrectomy, CKD receiving daily peritoneal infusions with 3.86% glucose Dianeal (CKDD), or Physioneal (both solutions from Baxter Healthcare, Castlebar, Ireland) (CKDP). At 16 weeks, a peritoneal function test was performed, and histology, ultrastructure, and hydroxyproline content of peritoneal tissue were assessed. Results Comparing CKD with NKF, peritoneal transport rates were higher, mesothelial cells (MC) displayed increased number of microvilli, blood and lymph vasculature expanded, vascular basal lamina appeared thicker, with limited areas of duplication, and fibrosis had developed. All alterations, except lymphangiogenesis, were enhanced by exposure to both dialysis fluids. Distinct MC alterations were observed in CKDD and CKDP, the latter displaying prominent basolateral protrusions. In addition, CKDP was associated with a trend towards less fibrosis compared to CKDD. Conclusions Chronic kidney failure itself induced peritoneal alterations, which were in part augmented by exposure to glucose-based dialysis solutions. Overall, the conventional and biocompatible solutions had similar long-term effects on the peritoneum. Importantly, the latter may attenuate the development of fibrosis.
PROBING PLANET FORMING ZONES WITH RARE CO ISOTOPOLOGUES
Authors: Yu Mo , Willacy Karen , Dodson-Robinson Sarah E. , Turner Neal J. , Evans II Neal J. 
Published: May 2016

ABSTRACT
The gas near the midplanes of planet-forming protostellar disks remains largely unprobed by observations due to the high optical depth of commonly observed molecules such as CO and H2O. However, rotational emission lines from rare molecules may have optical depths near unity in the vertical direction, so that the lines are strong enough to be detected, yet remain transparent enough to trace the disk midplane. Here we present a chemical model of an evolving T Tauri disk and predict the optical depths of rotational transitions of 12C16O, 13C16O, 12C17O, and 12C18O. The MRI-active disk is primarily heated by the central star due to the formation of the dead zone. CO does not freeze out in our modeled region within

around a sunlike star. However, the abundance of CO decreases because of the formation of complex organic molecules, producing an effect that can be misinterpreted as the “snow line.” These results are robust to variations in our assumptions about the evolution of the gas-to-dust ratio. The optical depths of low-order rotational lines of C17O are around unity, making it possible to see into the disk midplane using C17O. Combining observations with modeled C17O/H2 ratios, like those we provide, can yield estimates of protoplanetary disks’ gas masses.
THE MASS AND SIZE DISTRIBUTION OF PLANETESIMALS FORMED BY THE STREAMING INSTABILITY. I. THE ROLE OF SELF-GRAVITY
Authors: Simon Jacob B. , Armitage Philip J. , Li Rixin , Youdin Andrew N. 
Published: May 2016

ABSTRACT
We study the formation of planetesimals in protoplanetary disks from the gravitational collapse of solid over-densities generated via the streaming instability. To carry out these studies, we implement and test a particle-mesh self-gravity module for the Athena code that enables the simulation of aerodynamically coupled systems of gas and collisionless self-gravitating solid particles. Upon employment of our algorithm to planetesimal formation simulations, we find that (when a direct comparison is possible) the Athena simulations yield predicted planetesimal properties that agree well with those found in prior work using different numerical techniques. In particular, the gravitational collapse of streaming-initiated clumps leads to an initial planetesimal mass function that is well-represented by a power law,

, with

, which equates to a differential size distribution of

, with

. We find no significant trends with resolution from a convergence study of up to 5123 grid zones and

particles. Likewise, the power-law slope appears indifferent to changes in the relative strength of self-gravity and tidal shear, and to the time when (for reasons of numerical economy) self-gravity is turned on, though the strength of these claims is limited by small number statistics. For a typically assumed radial distribution of minimum mass solar nebula solids (assumed here to have dimensionless stopping time

), our results support the hypothesis that bodies on the scale of large asteroids or Kuiper Belt Objects could have formed as the high-mass tail of a primordial planetesimal population.
HYPERCALIBRATION: A PAN-STARRS1-BASED RECALIBRATION OF THE SLOAN DIGITAL SKY SURVEY PHOTOMETRY
Authors: Finkbeiner Douglas P. , Schlafly Edward F. , Schlegel David J. , Padmanabhan Nikhil , Jurić Mario , Burgett William S. , Chambers Kenneth C. , Denneau Larry , Draper Peter W. , Flewelling Heather , Hodapp Klaus W. , Kaiser Nick , Magnier E. A. , Metcalfe N. , Morgan Jeffrey S. , Price Paul A. , Stubbs Christopher W. , Tonry John L. 
Published: May 2016

ABSTRACT
We present a recalibration of the Sloan Digital Sky Survey (SDSS) photometry with new flat fields and zero points derived from Pan-STARRS1. Using point-spread function (PSF) photometry of 60 million stars with 16 < r < 20, we derive a model of amplifier gain and flat-field corrections with per-run rms residuals of 3 millimagnitudes (mmag) in griz bands and 15 mmag in u band. The new photometric zero points are adjusted to leave the median in the Galactic north unchanged for compatibility with previous SDSS work. We also identify transient non-photometric periods in SDSS (“contrails”) based on photometric deviations co-temporal in SDSS bands. The recalibrated stellar PSF photometry of SDSS and PS1 has an rms difference of {9, 7, 7, 8} mmag in griz, respectively, when averaged over 15′ regions.
TOWARD A NETWORK OF FAINT DA WHITE DWARFS AS HIGH-PRECISION SPECTROPHOTOMETRIC STANDARDS
Authors: Narayan G. , Axelrod T. , Holberg J. B. , Matheson T. , Saha A. , Olszewski E. , Claver J. , Stubbs C. W. , Bohlin R. C. , Deustua S. , Rest A. 
Published: May 2016

ABSTRACT
We present the initial results from a program aimed at establishing a network of hot DA white dwarfs to serve as spectrophotometric standards for present and future wide-field surveys. These stars span the equatorial zone and are faint enough to be conveniently observed throughout the year with large-aperture telescopes. The spectra of these white dwarfs are analyzed in order to generate a non-local-thermodynamic-equilibrium model atmosphere normalized to Hubble Space Telescope colors, including adjustments for wavelength-dependent interstellar extinction. Once established, this standard star network will serve ground-based observatories in both hemispheres as well as space-based instrumentation from the UV to the near IR. We demonstrate the effectiveness of this concept and show how two different approaches to the problem using somewhat different assumptions produce equivalent results. We discuss the lessons learned and the resulting corrective actions applied to our program.
FERMI LAT STACKING ANALYSIS OF SWIFT LOCALIZED GRBs
Authors: Ackermann M. , Ajello M. , Anderson B. , Atwood W. B. , Axelsson M. , Baldini L. , Barbiellini G. , Bastieri D. , Bellazzini R. , Bhat P. N. , Bissaldi E. , Bonino R. , Bottacini E. , Brandt T. J. , Bregeon J. , Bruel P. , Buehler R. , Buson S. , Caliandro G. A. , Cameron R. A. , Caragiulo M. , Caraveo P. A. , Cecchi C. , Charles E. , Chekhtman A. , Chiang J. , Chiaro G. , Ciprini S. , Claus R. , Cohen-Tanugi J. , Conrad J. , Cutini S. , D’Ammando F. , de Angelis A. , de Palma F. , Desiante R. , Di Venere L. , Drell P. S. , Favuzzi C. , Focke W. B. , Franckowiak A. , Funk S. , Fusco P. , Gargano F. , Gasparrini D. , Gehrels N. , Giglietto N. , Giordano F. , Giroletti M. , Godfrey G. , Grenier I. A. , Grove J. E. , Guiriec S. , Hewitt J. W. , Hill A. B. , Horan D. , Jóhannesson G. , Kocevski D. , Kouveliotou C. , Kuss M. , Larsson S. , Li J. , Li L. , Longo F. , Loparco F. , Lovellette M. N. , Lubrano P. , Mayer M. , Mazziotta M. N. , McEnery J. E. , Michelson P. F. , Mizuno T. , Monzani M. E. , Morselli A. , Murgia S. , Nemmen R. , Nuss E. , Ohno M. , Ohsugi T. , Omodei N. , Orienti M. , Orlando E. , Paneque D. , Perkins J. S. , Pesce-Rollins M. , Piron F. , Pivato G. , Porter T. A. , Racusin J. L. , Rainò S. , Rando R. , Razzano M. , Reimer A. , Reimer O. , Schaal M. , Schulz A. , Sgrò C. , Siskind E. J. , Spada F. , Spandre G. , Spinelli P. , Takahashi H. , Thayer J. B. , Tibaldo L. , Tinivella M. , Torres D. F. , Tosti G. , Troja E. , Vianello G. , Kienlin A. von , Werner M. , Wood K. S. 
Published: May 2016

ABSTRACT
We perform a comprehensive stacking analysis of data collected by the Fermi Large Area Telescope (LAT) of γ-ray bursts (GRBs) localized by the Swift spacecraft, which were not detected by the LAT but which fell within the instrument’s field of view at the time of trigger. We examine a total of 79 GRBs by comparing the observed counts over a range of time intervals to that expected from designated background orbits, as well as by using a joint likelihood technique to model the expected distribution of stacked counts. We find strong evidence for subthreshold emission at MeV to GeV energies using both techniques. This observed excess is detected during intervals that include and exceed the durations typically characterizing the prompt emission observed at keV energies and lasts at least 2700 s after the co-aligned burst trigger. By utilizing a novel cumulative likelihood analysis, we find that although a burst’s prompt γ-ray and afterglow X-ray flux both correlate with the strength of the subthreshold emission, the X-ray afterglow flux measured by Swift’s X-ray Telescope at 11 hr post trigger correlates far more significantly. Overall, the extended nature of the subthreshold emission and its connection to the burst’s afterglow brightness lend further support to the external forward shock origin of the late-time emission detected by the LAT. These results suggest that the extended high-energy emission observed by the LAT may be a relatively common feature but remains undetected in a majority of bursts owing to instrumental threshold effects.
THE UV–OPTICAL COLOR GRADIENTS IN STAR-FORMING GALAXIES AT 0.5 < z < 1.5: ORIGINS AND LINK TO GALAXY ASSEMBLY
Authors: Liu F. S. , Jiang Dongfei , Guo Yicheng , Koo David C. , Faber S. M. , Zheng Xianzhong , Yesuf Hassen M. , Barro Guillermo , Li Yao , Li Dingpeng , Wang Weichen , Mao Shude , Fang Jerome J. 
Published: May 2016

ABSTRACT
The rest-frame UV–optical (i.e., NUV − B) color index is sensitive to the low-level recent star formation and dust extinction, but it is insensitive to the metallicity. In this Letter, we have measured the rest-frame NUV − B color gradients in ∼1400 large (r
e > 0.″18), nearly face-on (b/a > 0.5) main sequence star-forming galaxies (SFGs) between redshift 0.5 and 1.5 in the CANDELS/GOODS-S and UDS fields. With this sample, we study the origin of UV–optical color gradients in the SFGs at z ∼ 1 and discuss their link with the buildup of stellar mass. We find that the more massive, centrally compact, and more dust extinguished SFGs tend to have statistically more negative raw color gradients (redder centers) than the less massive, centrally diffuse, and less dusty SFGs. After correcting for dust reddening based on optical-spectral energy distribution fitting, the color gradients in the low-mass (M
* < 1010
M
⊙) SFGs generally become quite flat, while most of the high-mass (M
* > 1010.5
M
⊙) SFGs still retain shallow negative color gradients. These findings imply that dust reddening is likely the principal cause of negative color gradients in the low-mass SFGs, while both increased central dust reddening and buildup of compact old bulges are likely the origins of negative color gradients in the high-mass SFGs. These findings also imply that at these redshifts the low-mass SFGs buildup their stellar masses in a self-similar way, while the high-mass SFGs grow inside out.
Suzanne Lenglen et la définition du professionnalisme dans le tennis de l’entre-deux-guerres
Authors: Castan-Vicente Florys 
Published: May 2016

En 1926, la championne de tennis Suzanne Lenglen (1899-1938) signe un contrat avec un manager pour jouer des matchs d’exhibition, provoquant des débats houleux sur la question du professionnalisme, dans la presse et au sein de la Fédération française de tennis qui décide de l’exclure. Une analyse de sa carrière avant et après son passage officiel au professionnalisme permet de montrer que dans son cas, malgré les discours de fermeté de la Fédération, les conditions de pratique des deux statuts ne sont pas si différentes. La décision de Suzanne Lenglen de passer professionnelle entraîne de plus une redéfinition du professionnalisme par la Fédération, qui distingue désormais les professeurs des « professionnels exhibition », afin de marginaliser ces derniers. À travers cet exemple, la définition de l’amateurisme et du professionnalisme apparaît davantage comme un enjeu de pouvoir aux mains de la Fédération que comme une catégorisation en accord avec les pratiques.