bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Simplified Engineering Model Integrated Stimulated Reservoir Volume (SRV) and Tight Formation Characterization With Multistage Fractured Horizontal Wells
Authors: Zhao Gang 
Published: October 2012

Abstract
Stimulated Reservoir Volume (SRV) is an engineering concept developed for the purposes of quickly evaluating the effective well drainage area and analyzing the actual performance of a multistage horizontal well in tight formation. Usually SRV is defined using microseismic event mapping. However, there are many other factors hindering the realization of the correct SRV value and largely impairing its engineering application.
A simplified integrating model with multiple regions that combines the near wellbore engineered reservoir area, the SRV region, the original tight formation area and the outbound reservoir region, named as region I, II, III and IV, respectively, were built and analyzed systematically, where the region I confines the horizontal wellbore with multiple artificial hydraulic fractures and allows the integration of complex skin factor distribution, region II intends to capture the influence of SRV under various parametric settings such as fracture networking and matrix-fluid mobility variations, region III accommodates the general geological information for the original large scale tight formation environment and region IV supports the information input for the outbound reservoir environment.
The multiple region modeling has been successfully built and applied to understand the relationship among wellbore, fracture, SRV and original reservoir formation. Theoretical study on the transient pressure and rate responses were conducted to address the technical challenge encountered. The results, presenting in a type curve format under various conditions, have shown that SRV region is strongly related to the fracture influenced/dominated boundary flow regime and appears as a region possessing a less than 1 slope in pressure and reciprocal rate derivative curves, which indicates that the flow process has reached the theoretical SRV boundary, i.e., the fracture influenced area/boundary. However, the derivative value would not reach one due to the inflow from the outside original reservoir region. This phenomenon is a symbolic feature of tight formation with SRV connectivity, as many field cases have been so indicated.
This work allows a quick estimation of SRV region, a better understanding of the influence of the complicated wellbore configurations and a way to characterize the reservoir connectivity between SRV and original/outbound tight formation reservoir.
Potential Investigation of Shale Gas Reservoirs, Southern China
Authors: Wei C. , Wang H. , Sun S. , Xiao Y. , Zhu Y. , Qin G. 
Published: October 2012

Abstract
The shale gas development has more than 3 decades of history. In China, the development is still in the early stage due the technology limitation. The estimated technically recoverable shale gas reserve is 882 Tcf in China. The predicted shale gas production in 2020 is 3.5 Tcf which will contribute 26% of natural gas consumption in China. In order to stabilize the gas output to meet the demand of economic development, increasing recoverable shale gas reserve becomes more and more important.
In this study, a Qiongzhusi reservoir was taken as an example to investigate the potential of shale gas in southern China. The methodologies involved in this investigation include experimental study on core analysis with Total Organic Content (TOC) and Vitrinite Reflectance, outcrops study, geostatistical analysis, and geo-modeling. Besides these methods, an irreplaceable step was to compare the reservoir conditions of given reservoir with successful developments in Barnett and Marcellus in the United States.
By integrating all above technologies and methods, the study forecasted the sedimentary facies, estimated shale gas distribution, and evaluated the petrophysical properties of the shale play. The result indicates that most of the Qiongzhusi reservoirs have promising thickness, favorable kerogen type (type I), high TOC, and encouraging maturity. This paper also predicted favorable zones in the middle and upper Yangtze area with properties of thickness more than 60 meters, TOC not less than 2.0%, and Vitrinite Reflectance from 2.5% to 4.6%.
The study would bring the reservoir engineers and geologists with detailed evidence to support the development of Qiongzhusi reservoirs, and furthermore, it offers the methodology to the research of other shale plays with similar properties.
Multiwell Analysis of Multifractured Horizontal Wells in Tight/Shale Gas Reservoirs
Authors: Nobakht M.. , Clarkson C. R. 
Published: October 2012

Abstract
Shale gas reservoirs have become a significant source of gas supply in North America owing to the advancement of drilling and stimulation techniques. Long horizontal wells completed with multiple-fracturing stages (MFHW) are the most popular method for exploiting shale gas reservoirs today and therefore, development of analysis methods for analyzing production data from these wells has gained tremendous attention in the last decade. The analysis methods developed so far are aimed to obtain understanding of fracture length, fracture conductivity, stimulated reservoir volume (SRV), contacted gas-in-place and other information for a MFHW being analyzed. Although single well analysis methods are of tremendous value, the industry also needs analysis methods for analyzing a group of MFHWs. In this paper, analysis methods developed for single well analysis of MFHWs are extended to analyze a group of MFHWs. These analysis methods are proved to be very useful for cases that adjacent wells are in communication (ex. fracturing one well affected the production of the adjacent wells). It is shown how these methods help engineers to diagnose and characterize the communication between MFHWs and use the results to optimize the size of frac job and spacing between horizontal wells in tight/shale gas plays.
Quantification of cm-Scale Heterogeneities in Tight-Oil Intervals of the Cardium Formation at Pembina, WCSB, Alberta, Canada.
Authors: Solano N. A. , Krause F. F. , Clarkson C. R. 
Published: October 2012

Abstract
A detailed, fine-scale, reservoir characterization study of (light) tight oil rock intervals in the Cardium Formation is performed using an innovative combination of X-Ray CT Scan technology, hardness and profile (probe) permeability measurements. This study aims to quantify the geometry, degree of heterogeneity, and several other key properties, of individual microlithofacies within the highly bioturbated sandstone lithofacies.
Contrasting bulk density values between these microlithofacies domains is identified using X-ray CT-Scan imagery reconstruction. Statistical analysis yields numerical information regarding geometry and connectivity of individual bodies for a given microlithofacies within the analyzed volume. Permeability, as estimated from a profile (probe) permeameter, and hardness of the samples, as quantified using a hardness index (from Leeb Hardness measurements), is investigated for a sub-centimeter 2D grid on slabbed surfaces. This detailed mapping allows the analysis of mm- to cm-scale correlations between rock quality and CT images.
Identified microlithofacies include SS1 and SS2 (sandstones), SH1 (shale), and PB (pyrite-filled burrows). Permeability can exceed 50 mD in SS1 microlithofacies, but generally is less than 1 mD for SS2 and 0.01 mD for SH1. Volumetric reconstruction of these microlithofacies yields approximately 85% total sandstone content for an average sample from tight-oil Cardium lithofacies (which is higher than visual assessment of 50-60% sandstone). The sandstone ratio of SS2/SS1 is between 3 and 5; microlithofacies SH1 and PB have a patchy distribution through the core. SS1 appears as highly disturbed relics of very thinly bedded patches, and sandstone-filled, subhorizontally oriented, sub-centimeter scale burrows. Relatively higher values of bulk density and hardness index characterize SS2 and SH1 microlithofacies.
The overall low permeability usually measured in this lithofacies can be attributed to the complex interplay between biological and physical sedimentary structures at the cm-scale, generating more or less randomly connected volumes with contrasting flow and storage capacity. This study provides a roadmap for more accurate property measurements and modeling at the core scale for this complex lithofacies of the Cardium Formation; we believe that this will also be useful for other tight oil reservoirs.
Evidence of Reopened Microfractures in Production Data Analysis of Hydraulically Fractured Shale Gas Wells
Authors: Apiwathanasorn Sippakorn , Ehlig-Economides Christine 
Published: October 2012

Abstract
The triple porosity analytical model provides a way to account for shale gas production from multiple hydraulic fractured horizontal wells that may have reopened a network of microfractures in the shale during hydraulic fracturing. This behavior has also been analytically modeled as multiple parallel finite conductivity hydraulic fractures in a dual porosity formation. In theory these models may reveal a series of flow regimes exhibiting linear, bilinear, and even trilinear flow. In practice, characterizing the various flow regimes is challenging because typically only one or two of them are likely to appear in any one transient data set.
This work concludes possible theoretical flow regime combinations which may be seen in fractured shale gas wells based on the dual and triple porosity models. Then sensitivity studies are investigated using typical shale gas formation and completion parameters to identify under what conditions in practice the transient data may reveal the flow regimes sensitive to microfractures and how likely or unlikely the those flow regimes could be present in field data.
Investigation of production rate and pressure field data from Barnett and Horn River shale formations illustrates that confirmation of a reopened fracture network, or "complexity", as this has been called by some authors, is not obvious even though some cases show the model related to reopened fracture network yield better matches than the homogeneous model.
This work emphasizes that interpretation using different models may yield significantly different results while still matching the observed behaviors equally well. Though buildup data may help to reduce uncertainties of parameters related to features visible at very early time, the variation of production forecast and recovery estimation is still expected if the model predicts large volume of reopened fracture network with ultra-low shale matrix permeability.
Obstetric Nephrology
Authors: Umans Jason G. 
Published: October 2012

Summary
Preeclampsia, a common and potentially devastating multisystem disorder unique to human pregnancy, represents a novel form of secondary hypertension with complex renal and systemic effects. Recent translational and clinical research reveals key pathophysiologic contributions due to dysregulation of angiogenic factors and of angiotensin signaling. Despite these insights, there are still difficulties in the clinical definition of preeclampsia and in the diagnosis of women with this disorder. Although recent research suggests the potential for new preventive and treatment strategies, most have not yet been shown ready for clinical use.
Is There Life after the Complete Loss of Analyst Coverage?
Authors: Mola Simona , Rau P. Raghavendra , Khorana Ajay 
Published: October 2012

ABSTRACT
This paper examines the value of sell-side analysts to covered firms by documenting the effects on firm performance and investor interest after a complete loss of analyst coverage for periods of at least one year. We find that analyst coverage adds value to a firm both because it reduces information asymmetries about the firm's future performance and because it maintains investor recognition for that firm's stock. After the introduction of regulations that curtailed the informational advantage of analysts in the early 2000s, the investor recognition role of analysts remains important. Firms that lose all analyst coverage continue to suffer a significant deterioration in bid-ask spreads, trading volumes, and institutional presence but do not show a significant difference in subsequent performance relative to covered peers. In addition, controlling for other factors, we find that firms that lose all analyst coverage for one year are significantly more likely to delist than their covered peers. Our results provide insight into the reasons why firms place so much importance on analyst coverage.
Caregiver placebo effect for dogs with lameness from osteoarthritis
Authors: Conzemius Michael G. , Evans Richard B. 
Published: October 2012

Abstract
Objective—To document the caregiver placebo effect in owners and veterinarians of dogs with lameness from osteoarthritis.
Design—Prospective, randomized, double-blinded, placebo-controlled, multicenter clinical trial.
Animals—58 dogs with lameness secondary to osteoarthritis.
Procedures—Dogs enrolled in the placebo arm of an FDA-approved study were evaluated to determine the relationship between subjective (caregiver responses) and objective (force platform gait analysis) patient outcome measures.
Results—A caregiver placebo effect for owners evaluating their dog's lameness occurred 39.7% of the time. A caregiver placebo effect occurred 44.8% of the time when veterinarians examined dogs for lameness at a walk, 44.8% of the time when veterinarians examined dogs for lameness at a trot, and 43.1% of the time when veterinarians evaluated dogs for signs of pain on palpation of the joint. This effect was significantly enhanced with time. Mean ground reaction forces (GRFs) remained unchanged for dogs during treatment with the placebo. Individually, of 58 dogs, 5 had GRFs that worsened by ≥ 5% over 42 days, 7 had GRFs that improved by ≥ 5% over 42 days, and 46 had GRFs that remained unchanged.
Conclusions and Clinical Relevance—A caregiver placebo effect was common in the evaluation of patient response to treatment for osteoarthritis by both pet owners and veterinarians. Force platform gait analysis was an unbiased outcome measure for dogs with lameness from osteoarthritis. A caregiver placebo effect should be considered when interpreting owner and veterinary reports of patient response to treatment.
Parathyroid hormone concentration in geriatric cats with various degrees of renal function
Authors: Finch Natalie C. , Syme Harriet M. , Elliott Jonathan 
Published: October 2012

Abstract
Objective—To determine whether cats in the nonazotemic stages of chronic kidney disease have increased plasma parathyroid hormone (PTH) concentrations as a compensatory physiologic mechanism to maintain plasma phosphate concentration within the reference interval.
Design—Prospective longitudinal study.
Animals—118 client-owned geriatric cats with various degrees of renal function.
Procedures—For each cat, a blood sample was obtained for plasma biochemical analysis and determination of plasma PTH concentration, and a urine sample was obtained for determination of urine specific gravity at study entry (baseline) and after 12 months. For a subset of 30 cats, plasma calcitriol concentration was determined at baseline. Cats were categorized into 1 of 3 groups on the basis of kidney function at the end of 12 months. At baseline and after 12 months, plasma concentrations of variables associated with calcium homeostasis were compared between the 3 groups and also within groups over time. Multivariable linear regression was used to identify variables associated with plasma PTH concentration.
Results—Plasma PTH concentration was significantly increased in cats that developed azotemia, compared with PTH concentration in cats that remained nonazotemic, and PTH concentration increased before changes in plasma calcium and phosphate concentrations were detected. A moderate positive association between plasma calcitriol and PTH concentrations was identified. Plasma PTH concentration was associated with age and plasma urea, creatinine, and total calcium concentrations in the final multivariable model.
Conclusions and Clinical Relevance—Results suggested that renal secondary hyperparathyroidism can develop prior to azotemia in cats, even in the absence of hyperphosphatemia and hypocalcemia.
Evaluation of hemostatic and fibrinolytic markers in dogs with ascites attributable to right-sided congestive heart failure
Authors: Zoia Andrea , Augusto Monica , Drigo Michele , Caldin Marco 
Published: October 2012

Abstract
Objective—To determine whether dogs with ascites secondary to right-sided congestive heart failure (CHF) have bleeding disorders associated with hypofibrinogenemia and discordant plasma fibrin-fibrinogen degradation products (FDPs) and D-dimer assay results (ie, a circulating concentration of FDPs higher than the reference range and a circulating concentration of D-dimer within the reference range).
Design—Retrospective case-control study.
Animals—80 client-owned dogs.
Procedures—Dogs with ascites secondary to right-sided CHF (group 1; n = 20), unhealthy dogs without cardiac disease (group 2; 40), and dogs with left-sided CHF (group 3; 20) were included in the study. Urine bile acids-to-creatinine concentration ratios were calculated as a marker of liver function. Differences among groups regarding coagulation profile analysis results and prevalence of discordant FDPs and D-dimer assay results were determined.
Results—No significant differences were detected among the 3 groups regarding urine bile acids-to-creatinine concentration ratios. Plasma fibrinogen concentration was significantly lower for group 1 versus groups 2 or 3. Prevalence of discordant FDPs and D-dimer assay results was significantly higher for group 1 versus groups 2 or 3. Eighteen group 1 dogs had discordant FDPs and D-dimer assay results. Ten of these dogs had concurrent hypofibrinogenemia, 2 of which had clinical signs of bleeding. Only 10 dogs in groups 2 or 3 had discordant FDPs and D-dimer assay results; none of these dogs had hypofibrinogenemia or clinical signs of bleeding.
Conclusions and Clinical Relevance—Dogs with right-sided CHF and ascites may be at increased risk for primary hyperfibrinogenolysis (ie, hypofibrinogenemia and discordant FDPs and D-dimer assay results).
2,8-dihydroxyadenine uroliths in a dog
Authors: Houston Doreen M. , Moore Andrew E. , Mendonca Sonia Z. , Taylor Judith A. 
Published: October 2012

Abstract
Case Description—A 43-kg (95-lb) 4-year-old neutered male mixed-breed dog was evaluated because of a 2-day history of dysuria.
Clinical Findings—Radiography and ultrasonography revealed hydronephrosis, hydroureter, and radiolucent, hyperechoic uroliths in the right kidney and ureter and the urinary bladder. Serum bile acids concentration was within the reference interval.
Treatment and Outcome—The uroliths in the bladder and right ureter were surgically removed and submitted for analysis. They were initially identified as urate uroliths; however, results of further analysis indicated uroliths were composed of 2,8-dihydroxyadenine (2,8-DHA), and 2,8-DHA was identified in a urine sample of the dog. Allopurinol was prescribed for the dog, and a purine-restricted diet was recommended.
Clinical Relevance—2,8-DHA uroliths are extremely rare in humans and dogs. Such uroliths may be underdiagnosed in humans because of variability of clinical signs and difficulty in differentiating 2,8-DHA and urate uroliths and crystalluria. Uroliths composed of 2,8-DHA may be misdiagnosed as urate uroliths in dogs.
Applicability of Gd-doped BaZrO3, SrZrO3, BaCeO3 and SrCeO3 proton conducting perovskites as electrolytes for solid oxide fuel cells
Authors: Zając Wojciech , Rusinek Dariusz , Zheng Kun , Molenda Janina 
Published: October 2012

Abstract
Four proton conducting oxides of perovskite structure: BaZrO3, SrZrO3, BaCeO3 and SrCeO3 doped with 5 mol.% of gadolinium are compared in terms of crystal structure, microstructure, sinterability, water sorption ability, ionic transference number, electrical conductivity and stability towards CO2. Relations between proton conductivity, structural and chemical parameters: pseudo-cubic unit cell volume, lattice free volume, tolerance factor, crystal symmetry and electronegativity are discussed. The grain boundary resistance is shown to be the limiting factor of total proton-conductivity for the materials examined. The highest proton conductivity was observed for BaCeO3, however, it turned out to be prone to degradation in CO2-containing atmosphere and reduction at high temperatures. On the other hand, Ba and Sr zirconates are found to be more chemically stable, but exhibit low electrical conductivity. Electrical conductivity relaxation upon hydration is used to calculate proton diffusion coefficient. Selected materials were tested as electrolytes in solid oxide fuel cells.
Application of chemometrics to identifying solid fuels and their origin
Authors: Sajdak Marcin 
Published: October 2012

Abstract
The aim of this work was to implement a chemometric analysis to detect the relationships between the analysed variables in samples of solid fuels. Efforts are being made to apply chemometrics methods in environmental issues by developing methods for the rapid assessment of solid fuels and their compliance with the required emission characteristics regulations. In the present investigation, two clustering techniques—hierarchical clustering analysis (HCA) and principal components analysis (PCA)—are used to obtain the linkage between solid fuel properties and the type of sample. These analyses allowed us to detect the relationships between the studied parameters of the investigated solid fuels. Furthermore, the usefulness of chemometrics methods for identification of the origin of biofuels is shown. These methods will enable control of the degree of contamination.
C&RT model application in classification of biomass for energy production and environmental protection
Authors: Sajdak Marcin , Piotrowski Olaf 
Published: October 2012

Abstract
Biomass is most often used to produce energy via its combustion and co-combustion along with conventional energy carriers. The prevalence of this method results from the lack of sufficient facilities that can provide a quick and simple chemical classification method, which would show a broader range of possible applications of biofuel in the energy industry. The aim of this study was the development of novel method of classification allowing for quick determine of the direction of the biomass usage by applying classification and regression models of trees (C&amp;RTs). The proper functioning of a C&amp;RT model is based on a very large database of results collected by the Institute for Chemical Processing of Coal during years of work in this field. The created model may be used as decision tool for grouping various biomass sources with respect to their further application in energy generation.