bluuebunny/crossref_metadata_2025 huggingface dataset:
Interfacility Transfers of Noncritically Ill Children to Academic Pediatric Emergency Departments
Authors: Li Joyce , Monuteaux Michael C. , Bachur Richard G.
Published: June 2012

OBJECTIVES:

We aimed to characterize the demographics, diagnoses, and management of transferred patients who were directly discharged from the emergency department (ED) or admitted less than 24 hours.

METHODS:

We conducted a retrospective, cross-sectional study of patients classified as interfacility ED transfers over a 12-month period in the Pediatric Health Information System database, an administrative database of 42 tertiary care pediatric US hospitals. The primary study outcomes were ED resource utilization at the receiving facility with a focus on children who were discharged directly from the ED or admitted less than 24 hours.

RESULTS:

Overall, 24 905 interfacility transfers were identified, accounting for 1.3% of the ED volume of these academic pediatric centers. Of these, 24.7% were discharged directly from the ED and 17.0% were admitted for less than 24 hours. Among those directly discharged from the ED, the 3 most common complaints were orthopedic problems, nonsurgical abdominal pain, and viral gastroenteritis; 20.7% received no medical or procedural intervention. Among those admitted for less than 24 hours, the 3 most common complaints were orthopedic problems, traumatic head injury, and gastrointestinal conditions.

CONCLUSIONS:

A significant proportion of interfacility transfers to academic pediatric EDs is discharged directly from the ED or is admitted for less than a day. These patients and their clinical outcomes provide insight into the educational needs and medical capabilities of referring hospitals and clinicians.
Effect of microelement loads on mustard (Sinapis alba L.) grown on calcareous sandy soil
Authors: Kádár Imre
Published: June 2012

Karbonátos Duna–Tisza közi homoktalajon vizsgáltuk a 0, 30, 90 és 270 kg·ha-1mikroelem-terhelés hatását a mustárra. A mikroelemek sóit egy ízben a kísérlet indulásakor, 1995 tavaszán szórtuk ki Cr2(SO4)3, K2Cr2O7, CuSO4, Pb(NO3)2, Na2SeO3és ZnSO4formájában. A 6 elem×4 terhelés = 24 kezelés×3 ismétlés = 72 parcellát jelentett, 7×5 = 35 m²-es parcellákkal. A termőhely a homoktalajokra jel-lemzően rossz vízgazdálkodású, aszályérzékeny és az NPK főbb tápelemekkel gyengén ellátott. A szántott réteg 0,7–1,0% humuszt, 2–3% CaCO3-ot tartalmaz, a talajvíz 5–10 m mélyen található. Alaptrágyaként 100–100–100 kg·ha-1N, P2O5és K2O hatóanyagot alkalmazunk évente az egész kísérletben. A főbb eredmények: – A száraz tavasz és az aszályos nyári időjárás eredményeképpen kis termések képződtek. A magtermés 0,8 t·ha-1, a szár + becő melléktermés 4,5 t·ha-1légszáraz tömeget ért el. A kísérlet 9. évében főként a Se-, és részben a 90, illetve 270 kg·ha-1Zn-kezelés utóhatása bizonyult toxikusnak. A Se-toxicitás döntően a generatív fázisban jelentkezett, a kontrollon mért szemtermés 85%-kal csökkent, az átlagos növénymagasság 96 cm-ről 53 cm-re mérséklődött, a melléktermés/főtermés aránya 5-ről 12-re tágult. A Na2SeO3formában adott szelén nagyobb része Ca-szelenátként már az altalajba mosódott. – Az ólom szennyezett talajon sem volt kimutatható a mustár szerveiben. A króm 2–3 mg·kg-1koncentrációt ért el a melléktermésben és 0,5 mg·kg-1mennyiséget a magban a Cr(VI)-kezelésben. A réz 2–3 mg·kg-1értékkel nőtt a nagyobb Cu-terheléssel, a cink maximálisan 20, ill. 33 mg·kg-1értékkel a magban, ill. a szárban. A szelén hiperakkumulációt mutatott 3-nagyságrendbeli dúsulással a kontrollhoz viszonyítva. A mustár magja élelmezési, hajtása/szára takarmányozási célokra alkalmatlanná vált az extrém Se-szennyezés eredményeképpen. – A felvett Cr 8 g [(CrIII)-kezelés)], 16 g [(CrVI)-kezelés)], Cu 33 g, Zn 197 g, Se 949 g mennyiséget tett ki hektáronként aratáskor a föld feletti biomasszában. Az Pb az 1 g·ha-1méréshatár alatt maradt. A 270 kg·ha-1Cr felvételéhez – hasonló körülmények között – 16675 évre [(CrVI)-kezelés)], a Cu kivonásához 8182 évre, a Zn esetén 1370 és a Se esetében 285 évre volna szükség. A fitoremediáció módszere nem tűnik hatékonynak erősen szennyezett talajok tisztításában. – Az 1 t szem + a hozzátartozó melléktermés ún. fajlagos elemtartalma extrém nagy értékeket mutatott: a P- és a K- 2–3-szor, a N- közel 4-szer, a Ca- és Mg-készlet 8-szorosan haladta meg a hazai szaktanácsadásban elfogadott tartalmakat részben az igen tág melléktermés/főtermés aránya, illetve az aszály miatt betöményedő ásványi elemkoncentrációk miatt. Nem ajánlhatók tehát a mustár elemigényének becsléséhez, félrevezetőek lehetnek. Valójában a száraz évben fel nem vett tápelemeket a következő évi növény hasznosíthatja, a trágyaigény csökkenhet. Kombájn aratásnál a felvett elemek zöme egyébként is a táblán marad, leszántják. Karbonátos termőhelyeken a Ca és Mg pótlása, kötöttebb talajokon a K-trágyázás válik feleslegessé.
Effectiveness of generic rosuvastatin in patients with ischaemic cerebrovascular disease
Authors: Szapáry László , Fehér Gergely
Published: June 2012

Statin therapy is the cornerstone of anti-atherosclerotic treatment, and it considered obligatory in the secondary prevention of atherosclerotic diseases. Rosuvastatin is well-known and efficacious lipid-lowering agent. Generic drugs are more frequently used instead of its ancestors. Generic rosuvastatin forms have been aproved recently to the Central European market, but their safety and efficacy have not been previously examined in cerebrovascular patient populations. Patients and methods: 109 patients with documented ischaemic cerebrovascular events were included in our study. 20 mg generic rosuvastatin significantly decreased total cholesterol (5.47 vs. 3.88 mmol/l, p<0.01), low-density lipoprotein (3.16 vs. 1.84 mmol/l, p<0.01) and trigliceride levels (1.77 vs. 1.33 mmol/l, p<0.05, and there was a non-significant high-density lipoprotein increasing tendency (1.27 vs. 1.36 mmol/l, p = 0.08). There was also a significant decrease in high-sensitive C-reactive protein levels (3.73 vs. 2.82 mg/l, p<0.05). Overall, 30% decrease in total cholesterol, 42% decrease in low-density lipoprotein, 25% decrease in trigliceride and high-sensitive C-reactive protein and 9% increase in high-density lipoprotein levels were observed. Conclusions: The generic rosuvastatin studied by the authors proved to be safe and efficacious lipid-lowering agent. Based on these short term results, in daily practice, generic rosuvastatin treatment seems to be cost-effective for the treatment of patients with ischemis cerebrovascular disease. Orv. Hetil., 2012, 153, 857–860.
Questioning Israel's Great Biodiversity—Relative to Whom? A Comment on Roll et al., 2009
Authors: Gavish Yoni
Published: June 2012

Each evolutionary-independent province has its own mainland species area relationship (SPAR). When using the power law SPAR (S = cAz), separate mainland SPARs are parallel in a log-log space (similar z value), yet they differ in species density per unit area (c value). This implies that there are two main SPAR-based strategies to identify biodiversity hotspots. The first treats all mainland SPARs of all provinces as if they form one global SPAR. This is the strategy employed by Roll et al. (2009) when questioning Israel's high biodiversity. They concluded that Israel is not a global biodiversity hotspot. Their results may arise from the fact that Israel's province, the Palaearctic, is relatively poor. Therefore, countries from richer provinces, whose mainland SPAR lies above the Palaearctic SPAR, are identified as global hotspots. The second strategy is to construct different mainland SPARs for each province and identify the provincial hotspots. In this manuscript I ask whether Israel's biodiversity is high relative to other countries within its province. For six different taxa, I analyzed data for Palaearctic countries. For each taxon, I conducted a linear regression of species richness against the country's area, both log transformed. The studentized residuals were used to explore Israel's rank relative to all other Palaearctic countries. I found that Israel lies above the 95th percentile for reptiles and mammals and above the 90th percentile for birds. Therefore, within the Palaearctic province, Israel is indeed a biodiversity hotspot.
Teste de caminhada de seis minutos para avaliação de mulheres com fatores de risco cardiovascular
Authors: Ribeiro Alexandre , Younes Camili , Mayer Diogo , Fréz Andersom Ricardo , Riedi Christiane
Published: June 2012

INTRODUÇÃO: A atividade física é uma das formas de prevenção ao aparecimento de fatores de risco cardiovascular, como a hipertensão arterial sistêmica (HAS) e o diabetes mellitus (DM). Uma das formas de avaliar é o teste de caminhada de seis minutos (TC6), que é um teste submáximo, simples de ser realizado, de baixo custo e alta reprodutibilidade. OBJETIVOS: Comparar o desempenho funcional de mulheres portadoras de risco cardiovascular, por meio do TC6. MÉTODOS: 45 mulheres foram alocadas em três grupos: G1 (com diagnóstico de HAS DM), G2 (diagnóstico de HAS) e G3 (voluntárias saudáveis). Inicialmente, as voluntárias realizaram o TC6 com caráter de aprendizado e uma hora depois o teste com caráter avaliativo. Considerou-se como variáveis pré e pós-teste a saturação periférica de oxigênio, a frequência cardíaca, a pressão arterial, a glicose e a distância percorrida. A análise estatística foi realizada com significância estipulada de p < 0,05. RESULTADOS: Todos os grupos aumentaram significativamente a distância percorrida no teste avaliativo, e tiveram acréscimo na pressão arterial e redução do índice glicêmico. CONSIDERAÇÕES FINAIS: O TC6 pode ser utilizado para avaliação da capacidade funcional de mulheres portadoras de HAS e DM como fatores de risco cardiovascular, demonstrando-se seguro e submáximo.
Influência de alterações posturais, acompanhadas por fotogrametria computadorizada, na produção da voz
Authors: Carneiro Paula Rossi , Teles Lídia Cristina da Silva
Published: June 2012

INTRODUÇÃO: Há considerável evidência da importância de uma postura adequada para um bom desempenho vocal. As alterações posturais podem influenciar diretamente a projeção da voz. OBJETIVO: Identificar a influência das diferentes posturas corporais na produção da voz. MATERIAIS E MÉTODOS: Foram realizadas as análises de 25 amostras vocais de um indivíduo que emitiu a vogal sustentada /a/ em três diferentes posturas corporais: a) ortostática natural; b) anteriorização da cabeça associada com extensão da coluna cervical; c) aumento da cifose torácica associada com anteriorização de cabeça. O indivíduo foi fotografado simultaneamente ao processo de gravação da voz. Para certificar-se de que o indivíduo estava sempre na mesma posição, as posturas foram acompanhadas por fotogrametria computadorizada pelo programa Corel Draw 10®. RESULTADOS: Os resultados da fotogrametria foram analisados pelo teste de Levene que não mostrou diferenças significativas em oito dos nove ângulos estudados. A voz foi avaliada por análise acústica e avaliação subjetiva perceptivo-auditiva. A acústica foi analisada pelos testes Anova e Tukey, que mostraram diferença na variável jitter - relacionada à qualidade vocal - entre as posturas A e B. A comparação das posturas A e B e A e C pela análise perceptivo-auditiva da voz mostrou mudanças no tom, piora na qualidade e na ressonância vocal. CONSIDERAÇÕES FINAIS: As mudanças encontradas na voz provam que a melhor produção do som é na postura ereta. O fisioterapeuta é o profissional indicado para a orientação postural e correção das más posturas.
Relação entre a Avaliação da Coordenação e Destreza Motora (Acoordem) e a Classificação Internacional de Funcionalidade, Incapacidade e Saúde (CIF)
Authors: Cardoso Ana Amélia , Magalhães Lívia de Castro , Lacerda Tatiana Teixeira Barral de , Andrade Peterson Marco de Oliveira
Published: June 2012

INTRODUÇÃO: A Classificação Internacional de Funcionalidade, Incapacidade e Saúde (CIF) visa a proporcionar uma base científica para a compreensão e o estudo da saúde e das condições relacionadas, podendo ser utilizada para nortear a criação e utilização de medidas de desfecho em reabilitação. A Avaliação da Coordenação e Destreza Motora (Acoordem) é um teste brasileiro, criado para detectar atraso motor em crianças de 4 a 8 anos. OBJETIVOS: Os objetivos deste estudo foram: a) associar as subcategorias da CIF aos itens da Acoordem; e b) determinar se os itens da Acoordem se encaixam na estrutura da CIF. MATERIAIS E MÉTODOS: Uma terapeuta ocupacional e um fisioterapeuta codificaram independentemente os itens contidos na Acoordem, fazendo o linking com a CIF. Para os itens em que não houve concordância entre os pesquisadores, foi usada a opinião de outras duas pesquisadoras, uma terapeuta ocupacional e uma fisioterapeuta. RESULTADOS: Os itens da Acoordem foram associados aos componentes b (funções do corpo), d (atividades e participação), e (fatores ambientais) e f (fatores pessoais). Não houve itens relacionados com o componente s (estrutura do corpo) e apenas três itens foram codificados como nc (não coberto pela CIF). DISCUSSÃO E CONCLUSÃO: Os itens da Acoordem puderam ser relacionados à estrutura da CIF. Profissionais e pesquisadores da área de reabilitação podem usar a Acoordem para obter dados acerca da atividade e participação em crianças com problemas de coordenação motora, pois sua terminologia e abrangência está de acordo com a perspectiva biopsicossocial da OMS.
Unraveling the drivers of community dissimilarity and species extinction in fragmented landscapes
Authors: Banks-Leite Cristina , Ewers Robert M. , Metzger Jean Paul
Published: June 2012

Communities in fragmented landscapes are often assumed to be structured by species extinction due to habitat loss, which has led to extensive use of the species–area relationship (SAR) in fragmentation studies. However, the use of the SAR presupposes that habitat loss leads species to extinction but does not allow for extinction to be offset by colonization of disturbed‐habitat specialists. Moreover, the use of SAR assumes that species richness is a good proxy of community changes in fragmented landscapes. Here, we assessed how communities dwelling in fragmented landscapes are influenced by habitat loss at multiple scales; then we estimated the ability of models ruled by SAR and by species turnover in successfully predicting changes in community composition, and asked whether species richness is indeed an informative community metric. To address these issues, we used a data set consisting of 140 bird species sampled in 65 patches, from six landscapes with different proportions of forest cover in the Atlantic Forest of Brazil. We compared empirical patterns against simulations of over 8 million communities structured by different magnitudes of the power‐law SAR and with species‐specific rules to assign species to sites. Empirical results showed that, while bird community composition was strongly influenced by habitat loss at the patch and landscape scale, species richness remained largely unaffected. Modeling results revealed that the compositional changes observed in the Atlantic Forest bird metacommunity were only matched by models with either unrealistic magnitudes of the SAR or by models ruled by species turnover, akin to what would be observed along natural gradients. We show that, in the presence of such compositional turnover, species richness is poorly correlated with species extinction, and z values of the SAR strongly underestimate the effects of habitat loss. We suggest that the observed compositional changes are driven by each species reaching its individual extinction threshold: either a threshold of forest cover for species that disappear with habitat loss, or of matrix cover for species that benefit from habitat loss.
Fear of the dark or dinner by moonlight? Reduced temporal partitioning among Africa's large carnivores
Authors: Cozzi Gabriele , Broekhuis Femke , McNutt John W. , Turnbull Lindsay A. , Macdonald David W. , Schmid Bernhard
Published: June 2012

Africa is home to the last intact guild of large carnivores and thus provides the only opportunity to investigate mechanisms of coexistence among large predator species. Strong asymmetric dominance hierarchies typically characterize guilds of large carnivores; but despite this asymmetry, subdominant species may persist alongside their stronger counterparts through temporal partitioning of habitat and resources. In the African guild, the subdominant African wild dogs and cheetahs are routinely described as diurnal and crepuscular. These activity patterns have been interpreted to result from the need to avoid encounters with the stronger, nocturnal spotted hyenas and lions. However, the idea that diel activity patterns of carnivore species are strongly shaped by competition and predation has recently been challenged by new observations. In a three‐year study in the Okavango Delta, we investigated daily activity patterns and temporal partitioning for wild dogs, cheetahs, spotted hyenas and lions by fitting radio collars that continuously recorded activity bursts, to a total of 25 individuals. Analysis of activity patterns throughout the 24‐h cycle revealed an unexpectedly high degree of temporal overlap among the four species. This was mainly due to the extensive and previously undescribed nocturnal activity of wild dogs and cheetahs. Their nocturnal activity fluctuated with the lunar cycle, represented up to 40% of the diel activity budget and was primarily constrained by moonlight availability. In contrast, the nocturnal activity patterns of lions and hyenas were unaffected by moonlight and remained constant over the lunar cycle. Our results suggest that other ecological factors such as optimal hunting conditions have shaped the diel activity patterns of subdominant, large predators. We suggest that they are “starvation driven” and must exploit every opportunity to obtain a meal. The benefits of activity on moonlit nights therefore offset the risks of encountering night‐active predators and competitors.
Patterns of Intimate Partner Violence in Young Adult Couples: Nonviolent, Unilaterally Violent, and Mutually Violent Couples
Authors: Marcus Robert F.
Published: June 2012

This study examined nonviolent (NV), unilaterally violent (UV), and mutually violent (MV) patterns of perpetrated intimate partner violence in relation to dyadic relationship quality and partner injury. The respondents were 1,294 young adult, Add Health partners (AHP) and their non-Add Health partners (NAHP), in dating, engaged, or in marital relationships, who were participants in Wave III of the National Longitudinal Study of Adolescent Health (Add Health). Using both partner reports of perpetration to classify intimate partner violence (IPV) patterns resulted in 25% of couples with a MV pattern, and 75% of couples with a UV pattern; among those couples (41%) reporting any perpetrated IPV. Results also showed poorer relationship quality and higher partner sensation-seeking scores among MV and UV couples when contrasted with NV couples. Those couples with MV patterns were more likely to contain partner injury than those with UV patterns.
Exposure to Harsh Parenting and Pornography as Explanations for Males’ Sexual Coercion and Females’ Sexual Victimization
Authors: Simons Leslie Gordon , Simons Ronald L. , Lei Man-Kit , Sutton Tara E.
Published: June 2012

Sexual violence against women is a major concern to researchers and policy makers, as well as to the general public. This study uses a sample of more than 2,000 college students to investigate the extent to which exposure to harsh parenting practices and sexually explicit materials contributes to perpetration and victimization. Findings indicate that frequent corporal punishment in the family of origin combined with consumption of pornographic materials increased the probability that males reported engaging in coercive sexual practices. For females, both frequent corporal punishment and exposure to paternal hostility combined with consumption of pornographic materials were associated with higher levels of reported sexual victimization. These results provide increased understanding of the impact of pornography use among a nonclinical sample, as well as the consequences of experiencing harsh corporal punishment in one’s family of origin, on the sexual victimization of females.
Teachers Bullied by Students: Forms of Bullying and Perpetrator Characteristics
Authors: Kauppi Teemu , Pörhölä Maili
Published: June 2012

The focus of this study is on the forms in which the bullying of school teachers by students manifests itself, the characteristics of the students who engage in the bullying, and the manner in which the students who engage in bullying behave in their own peer relationships. The data was gathered from primary and lower secondary school teachers by means of an Internet survey. The answers of 70 teachers who had experienced bullying by their students are examined.

The teachers had been exposed to different forms of bullying by students. They had typically been bullied by male students. In most cases, the bullying had been perpetrated by an individual student or a small group of students. According to the teachers’ assessment, the majority of the students who bullied them also bullied their fellow students.
Parametric Study of Fracture Treatment Parameters for UltraTight Gas Reservoirs
Authors: Abaa Kelvin , Wang John Yilin , Ityokumbul Mku Thaddeus
Published: June 2012

Tight gas reservoirs are expected to contribute significantly to the gas and energy supply all over the world. However, the productivity of tight gas wells, especially in the ultra-tight formations, is often lower than expected. One of the needed improvements in reservoir stimulation technology is in the advancement of fracturing fluids and techniques that can help create long and highly conductive fractures and reduce phase trapping at the face of the fracture. Introduction of aqueous based fluids in ultralow permeability sands during hydraulic fracturing decreases the effective gas permeability and ultimate gas recovery. Unfortunately most fracture fluids currently deployed are aqueous based owing to their ease of preparation and low cost. This paper aims to investigate the effect of different fracture fluid systems and fracture treatment parameters and then determine one that achieves a balance of minimal fluid retention, optimal fracture geometry and low cost for ultra-tight gas reservoirs.

In this paper, a dataset of reservoir properties, petrophysical properties, and fracture treatment parameters has been developed based on a complete review of published geological and engineering data of ultra-tight gas reservoir. Then based on numerical parametric studies, the effect of pertinent design factors on hydraulic fracture propagation and geometry is quantified with a fracture simulator. The factors investigated include volumetric injection rate, gel loading and proppant size. Parametric variation of seven different injection rates, seven different fracture fluids, and three different proppants was studied.

A final fracture treatment that achieves maximum fracture length, fracture width and proppant conductivity is determined to be optimal. Results from simulations show that optimal fracture geometry and fracture conductivity based on pumping limitations is obtained at an injection rate of 100 bpm, a gel loading of 50 pptg of linear gel and a proppant size of 20/40 mesh sand.

This paper brings new understanding of fracture behavior in ultra-tight gas reservoirs and serves as a guide for improved hydraulic fracturing practices in ultra-tight gas basins throughout the United States.
Lowering Tubing in Jonah Field Offset Production Decline
Authors: Ogugbue Chinenye E. , Hopkins Cody R. , Greenly Leah R. , Wilson Robert K. , Gates Gordon E.
Published: June 2012

Declining reservoir pressure and rate in the Jonah field has led to the common problem of liquid loading. As fluids accumulate the downhole pressure increases which decreases the available drawdown that allows fluids to flow into a wellbore. Jonah wells are completed in the 2000 - 3500-ft thick Lance Formation, using 8-16 hydraulic fracturing stages. With initial end of tubing (EOT) depths set above the top perforation for most wells, this left approximately 1500-3000 feet (gross pay) of perforations below the EOT. With lifting velocities significantly greater in larger diameter casing than tubing, a liquid column was developing below the EOT and engineering and operational attention was needed to improve field performance.

Improving on the operational efficiency involved the implementation of recommended actions from a cross-functional well by well review group that received input and support from all Jonah asset members. The approach focused on how to improve liquid removal and optimize gas production from wells identified as liquid-loaded. In addition to installing plunger lift systems and injecting soaps, in 2008 a program was started to lower production tubing in wells by approximately 50-70% into perforations; the purpose was to reduce the column of fluid in the wellbore by helping more efficiently unload fluids using the reduced critical flow rate in the tubing and allowing plungers deeper access to the column of liquid covering the perforated interval.

This paper discusses the results of lowering the EOT of over 100 gas producing wells in the Jonah field. The wells showed an average sustained uplift of approximately 105 mcfd, with undiscounted payout of less than 12 months. In addition, on wells that have had the tubing lowered, their decline curves appear to flatten out, offsetting anticipated double digit decline. Practical methods of selecting candidate wells and the new EOT are presented and discussed.
Wellbore Real-time Monitoring and Analysis for Shale Reservoirs
Authors: Gonzalez Luis E. , Chokshi Rajan N.
Published: June 2012

Advances in directional drilling and reservoir stimulation techniques have dramatically increased gas production from wells drilled in shale reservoirs that were considered uneconomical not too long ago. In spite of many advances made on understanding the production behavior of this type of reservoirs, there are many unknowns that still do not have a proper answer. Particularly, it is difficult to predict productivity from cores, logs or DSTs or from early well production performance. Drainage volumes are uncertain and well spacing is based on trial and error methods.

The use of micro-seismic and production logs has helped in the fracture evaluation to determine the drainage volume and fracture inflow. Micro-seismic can provide useful information on the development of fracture symmetry, half-length, azimuth, width and height, and their dependence on the stimulation treatment parameters and reservoir characteristics. Additionally, these fracture geometries in conjunction with other measured or calculated parameters (rates, inflow models) can be used to better understand fracture modeling and production characteristics.

Reviews of production logs have indicated that only a percentage of the fractures are contributing to the production, however considering that this is a transient system, a snapshot measurement is not enough to understand the behavior of the fractures and their contribution over time. It is necessary to have continuous or permanent information from within the wellbore to establish which fractures are contributing and how much.

The near-wellbore temperature distribution yielded by distributed temperature sensing (DTS) or multi-point or array temperature sensing (ATS) can be used to determine the relative amount of fluids that each perforation interval contributes. If this information is combined with one or more pressure measurements and a real-time surface multiphase flow measurement in conjunction with an inflow model for each fractured interval, a production allocation could be calculated for each fracture. This approach is analogous to a traditional well allocation where a daily aggregated measurement at the production plant is back allocated to each well based on wellhead measurements like pressure, temperature and well performance. This paper will provide details on the above mentioned analogy and the use of these technologies to analyze the fracture behavior in horizontal wells in shale reservoirs.
Relating Fracture Network Characteristics to Shale Gas Reserve Estimation
Authors: Akbarnejad-Nesheli Babak , Valkó Peter P. , Lee W. John
Published: June 2012

The Stretched Exponential production Decline Model (SEDM) provides a flexible framework for forcasting production and estimating reserves in unconventional reservoirs. In the following we use the Discrete Fracture Network (DFN) concept to interpret the SEDM results obtained previously. Our study proposes that the SEDM exponent parameter, n can be related to the scale independent characteristics of the created fracture network that in turn can be considered non-varying in a given field (or larger group of wells in the same geological settings and of similar completion type.) Our hypothesis is supported by dry gas flow simulation involving stochastic generation of DFN with various characteristics. The effect of variations in natural fracture lengths, apertures, density, and connectivity are considered along with induced hydraulic fracture dimensions. In view of our findings we present another conditioning approach to robust decline curve analysis and provide application examples for selected Barnett Shale wells.
Optimizing Fracture Spacing to Induce Complex Fractures in a Hydraulically Fractured Horizontal Wellbore
Authors: Jo Hyunil
Published: June 2012

As conventional hydrocarbon reservoirs are depleted and new sources sought for economic and security reasons, unconventional reservoirs attract the oil and gas industry's attention. Among the unconventional options, shale gas reservoirs have become prominent. After many years of working to effectively recover hydrocarbons from the shale gas reservoirs, it has been accepted that creating complex fracture networks by hydraulic fracturing is one of the most efficient ways to produce gas from these reservoirs. Although several factors affect development of the complex fracture networks, the in-situ stress anisotropy (i.e. the maximum in-situ horizontal stress – the minimum in-situ horizontal stress) is the most significant factor. Low in-situ stress anisotropy increases the chance of creating complex fracture networks with hydraulic fracturing. In order to compensate for the in-situ stress anisotropy, M.Y. Soliman suggested arranging a sequence of fracturing stages to make use of the induced stress caused by the net fracturing pressure (Soliman et al. 2008; East et al. 2011). This method is so called Texas Two Step method (TTSM). This research analyzes the effectiveness of TTSM by utilizing the boundary element method (BEM). In addition, the research analyzes and models fracture geometries caused by interaction among multiple hydraulic fractures to determine the optimal fracture spacing for multistage fracturing operations. From the results, this research concludes that curved fractures can enhance or vitiate the stress contrasts induced by the net fracturing pressure, depending on the shape of the curved fractures. It further calculates optimal fracture spacing for operations using the Texas Two Step method.
Comparison of Production Results from Open Hole and Cemented Multistage Completions in the Marcellus Shale
Authors: Snyder Daniel , Seale Rocky
Published: June 2012

With estimates of recoverable reserves at approximately 500 Tcf, the Marcellus Shale has become one of the main unconventional shale targets in the U.S. The Marcellus is part of the Appalachian Basin and underlies 95,000 sq. miles of Pennsylvania, New York, Ohio, Maryland, and West Virginia. The Marcellus is a challenging target due to formation characteristics, making it cost-intensive to develop. In addition, operators working in the Marcellus have had to contend with public opposition to hydraulic fracturing, prompting them to look for technologies to make this process more efficient and less resource intensive.

This paper compares open hole multistage fracturing systems (OHMS) and cemented casing, "plug and perf" (CCPP) completions and presents the evolution of completion methods utilized in the Marcellus Shale. Production results from horizontal wells in two counties completed with OHMS are compared to offset wells completed with the CCPP method. System details, the fracture methods used, as well as the operational efficiencies of OHMS compared to other horizontal completions methods are discussed. In addition, an update on the recent advances in technologies that have been made since the introduction of OHMS to the Marcellus Shale is presented.

Higher cumulative production results at six, 12, and 24 months in both geographic areas of analysis demonstrate the successful application of OHMS systems in the Marcellus Shale. Comparing the two completion methods also highlights the increased efficiency of OHMS systems compared to CCPP. With decreased time and cost requirements, OHMS completions are the clear choice in the Marcellus Shale. Therefore, this paper demonstrates that OHMS technology provides a long-term solution for the life of wells in shale plays. Although the focus is on the Marcellus Shale, principles from this paper can be applied to any unconventional shale reservoir.
The Importance of Slow Slip on Faults During Hydraulic Fracturing Stimulation of Shale Gas Reservoirs
Authors: Zoback Mark D. , Kohli Arjun , Das Indrajit , McClure Mark
Published: June 2012

We utilize several lines of evidence to argue that slow slip on pre-existing fractures and faults is an important deformation mechanism contributing to the effectiveness of slick-water hydraulic fracturing for stimulating production in extremely low permeability shale gas reservoirs. First, we carried out rate and state friction experiments in the laboratory using shale samples from three different formations with a large range of clay content. These experiements indicated that slip on faults in shales comprised of less than about 30% clay is expected to propagate unstably, thus generating conventional microseismic events. In contrast, in formations containing more than about 30% clay are expected to slip slowly. Second, we illustrate through modeling that slip induced by high fluid pressure on faults that are poorly oriented for slip in the current stress field is expected to be slow, principally because slip cannot occur faster than fluid pressure propagates along the fault plane. Because slow fault slip does not generate high frequency seismic waves, conventional microseismic monitoring does not routinely detect what appears to be a critical process during stimulation. Thus, microseismic events are expected to give only a generalized picture of where pressurization is occurring in a shale gas reservoir during stimulation which helps explain why microseismicity does not appear to correlate with relative productivity. We review observations of long-period-long-duration seismic events that appear to be generated by slow slip on mis-oriented fault planes during stimulation of the Barnett shale. Prediction of how pre-existing faults and fractures shear in response to hydraulic stimulation can help optimize field operations and improve recovery.
Shale Gas Drilling Experience and Lessons Learned from Eagle Ford
Authors: Guo Quanxin , Ji Lujun , Rajabov Vusal , Friedheim James , Portella Christin , Wu Rhonna
Published: June 2012

As an industry, we are still in the early stages of the learning curve for shale gas drilling although many shale gas wells have been drilled in recent years. Data from over one thousand wells drilled in the Maverick basin since 2003 were retrieved from an internal drilling database. Among them are over two hundred horizontal wells from the Eagle Ford shale play drilled by 31 different operators between 2008 and early 2011. The analyses of drilling performance data of these horizontal wells offer the establishment of general practice guidelines and recognition of opportunities for improvement in Eagle Ford shale drilling.

Oil-based drilling fluid, or "mud" (OBM) is a typical drilling fluid type currently used to drill from the surface casing shoe to the total depth (TD) in the Eagle Ford shale play. However, water-based mud (WBM) has also been used since the development of the Eagle Ford shale play. A comparative analysis was performed between oil-based and water-based drilling fluids to assess their performances and to identify the key challenges and potential areas for improvement when drilling in the Eagle Ford shale. The analyses included mud chemistry, drilling performance, mud weight and well architectures such as bit sizes, casing sizes and depths of the casing shoe, as well as lateral length. A statistical analysis (P10, P50, and P90) was also performed to evaluate industry-wide drilling performance such as drilling days for wells of various depths. Comparisons were made among different drilling fluid types and different operating companies.

The statistical analysis shows that although overall performance of water-based drilling fluids lags behind that of oil-base fluids in Eagle Ford shale drilling, a certain WBM system shows promising performance close to that of oil-based drilling fluids. The analysis shows that there is a general trend of decreased drilling days per footage over time and a large variation in total drilling days for similar well depths and trajectories. This indicates that although the drilling industry as a whole has improved drilling in the Eagle Ford shale over the years, there is still a large opportunity for improvement. One interesting finding is that some operators can drill wells in fewer days than the industry average even though their drilling fluid cost is slightly more expensive than the industry average. As a result of reduced drilling time, their overall drilling costs are reduced.

Lab test results with different fluid types show that the failure mechanism and shale-fluid interaction of the Eagle Ford shale is different from dispersion or swelling which are typical of traditional shales. The analyses and results of this study on drilling performance data provide lessons learned and general guidelines for current drilling practices and opportunities for improvement such as drilling fluid selections, mud weight, and well architectures in the Eagle Ford shale play.
Assessing the Spacing of Stages in Plug and Perf Completions in the Marcellus Shale
Authors: Baig Adam M. , Urbancic Ted , Goldstein Shoshana
Published: June 2012

Completion programs for hydraulic fracture stimulations are planned to optimize the spacing of wells and perforation clusters such that the largest volume of the reservoir can be accessed through the promotion of a discrete fracture network in the reservoir. Such treatments also seek to minimize costs associated with pumping proppants and fluids down wells by ensuring that these injectants reach their target formations, stay in zone, and act to promote the stimulation of the reservoir. From this viewpoint, it is seen as desirable to minimize the overlap of treatment volumes between neighbouring wells and stages to avoid the preferential diversion of proppants and fluids into the previously stimulated volumes of the reservoir. However, it has also been argued that the creation of new fractures in a previously treated volume promotes a complex fracture network enhancing drainage. When these stimulations are monitored from multiple geophone arrays surrounding the treatment zone, seismic moment tensor inversion (SMTI) analysis offers the ability to test these hypotheses by inferring if the microseismic events are related to the opening of or closure of pre-existing natural or newly created fractures. In this paper, we discuss event clusters that occur with a significant degree of overlap between neighbouring stages in the Marcellus Shale. Because the events were monitored with multi-array sensor configuration, the SMTI calculations can be conducted with a high degree of accuracy. SMTI allows for the orientations of the underlying fractures to be determined, allowing us to construct a discrete fracture. Further analysis of the orientations of the underlying fractures also enable us to assess which fractures are being activated in relation to the pre-existing structures in the reservoir, and how the activation of those structures correlates to estimates of stimulated reservoir volume which we relate to the regions of the reservoir where an complex, intersecting fracture network is being activated by the stimulation.
Optimal Well Spacing Configurations for Unconventional Gas Reservoirs
Authors: Sahai Vivek , Jackson Greg , Rai Rakesh , Coble Larry
Published: June 2012

Determining the optimal number of wells for infill drilling in an unconventional reservoir is a critical endeavor for shale gas operators as many leases are held only by production. To develop a given section, operators must select locations and completion designs for all wells. The planned well placement and completion design will dictate the economic viability and production of the field for the asset's life. The key factors impacting performance in shale gas reservoirs can be broadly divided into two categories: controllable and uncontrollable. Uncontrollable factors include rock properties such as porosity, water saturation, net-to-gross, initial pressure, permeability, natural fractures, and fluid properties. Controllable factors related to producibility that can be optimized include well design, completion design, well placement, surface facilities design, and operating conditions.

Development schemes must consider both engineering and economic risks that include reduction of reservoir permeability due to rock compaction and changes in completion characteristics/efficiency. To determine optimal development, these factors have to be evaluated. This paper outlines the results of well optimization studies initiated from a production performance analysis of over 100 wells in the Haynesville Shale and over 300 wells in the Marcellus Shale. Both analytical and numerical tools were used in the presented workflow. The study results indicate a threshold of reservoir and completion properties below which any well drilled may be uneconomic based on our financial assumptions. Original gas-in-place (OGIP), rock brittleness, and fracture height containment were considered with regard to stimulated reservoir volume, SRV. The effect of natural fractures was also studied. With low gas prices, optimal capital allocation is a critical development component and is an issue that all operators face. The subsequent results presented could save operators myriad hours of simulation effort while potentially saving millions of dollars by eliminating unnecessary wells.
Focus on Cement Design and Job Execution Increase Success for Shale Cementing Operations
Authors: Bassett Jessica , Watters Jeff , Sabins Fred , Febbraro Anthony
Published: June 2012

In recent years, drilling and production activity in US shale gas has been increasing. This high volume of work has led to the use of manufacturing-style well construction. Each area has its own challenges; however, problematic wells are prevalent in many shale plays. A major study in the Haynesville shale targeted the manufacturing-style methodology. Over the course of the study, more than 160 cement jobs were analyzed including surface, intermediate and production strings. This study implemented the use of careful engineering decisions that were focused on the issues and challenges specific to wells in this area. This was achieved through analyzing and optimizing the laboratory operations, design of cement systems, bulk plant and job site processes. This study shows by taking the proper steps to design these processes, a manufacturing style approach can be very successful when applied in challenging shale cementing operations.
Optimizing Completion Designs for Horizontal Shale Gas Wells Using Completion Diagnostics
Authors: Bartuska J. E. , Pechiney J. J. , Leonard R. S. , Woodroof R. A.
Published: June 2012

In horizontal shale completions, one of the primary goals is to maximize contact with the most reservoir rock and effectively drain the complex fracture network that has been created during the stimulation process. This paper covers a five-well case study in the Marcellus Shale where completion diagnostics were used to evaluate and optimize the completion process. The case histories will detail key completion parameters and how they changed over time based on various diagnostic results.

Completion diagnostics such as proppant and fluid tracers can be integrated with production, stimulation and geologic data to provide useful information as to the effectiveness of the completion design. Proppant tracers have been utilized in horizontal shale basins throughout North America to evaluate near-wellbore fracture initiation, identify un-stimulated perforations, and evaluate proppant interference between stimulated wellbores. Fluid tracers are currently being used to analyze lateral clean-up over time and to quantify fracture fluid interference between wells.

In this case study, these diagnostic technologies were instrumental in addressing several completion design questions. Proppant tracers were used to evaluate cluster and stage spacing and also identified proppant interference with adjacent wells. Fluid tracers were utilized to evaluate overall load fluid recoveries for various wellbore trajectories and helped quantify the source and amount of interference between wells.
Mean Corpuscular Volume as a Marker for Adherence to Zidovudine-Containing Therapy in HIV-Infected Adults
Authors: Mugisha Joseph O , Donegan Katherine , Fidler Sarah , Ramjee Gita , Hodson Andrew , Dunn David T , Porter Kholoud , Kaleebu Pontiano
Published: June 2012

Objectives:

To assess whether mean corpuscular volume (MCV) is useful in detecting non-adherence to AZTcontaining therapy.

Design:

Observational study within randomised controlled trial.

Methods:

We combined data from two treatment arms in SPARTAC, an RCT of short-course cART in primary HIV infection, classifying participants as responders (HIV-RNA decrease ≥1 log10or reaching <400copies/ml) or nonresponders following cART initiation. We assessed the sensitivity and specificity of using different percentage increases in MCV for accurately differentiating between responders and non-responders. We further examined changes in MCV levels up to 24 weeks after protocol-indicated cART cessation.

Results:

Of 119 participants included in this analysis, 73 (61%) were women, 71 of whom were randomised in Africa. Ninety-eight (88%) and 84 (85%) were classified as responders at 4 and 12 weeks respectively following cART initiation. MCV increased by a mean 3% and 1% at week 4, and 14% and <1% at 12 weeks for responders and non-responders. A 2% MCV increase at 4 weeks had 62% sensitivity and specificity for identifying virological response. At 12 weeks, an 8% increase had 89% sensitivity and specificity. In responders, MCV remained lower for individuals in African compared to non-African sites throughout and rose from 85vs90 fL at cART start to 96vs103 fL at 12 weeks post-initiation then fell to 88vs93 fL and 86vs89 fL at 12 and 48 weeks post-cessation.

Conclusion:

In low-income countries, where HIV RNA may be unavailable, 12-weekly MCV measurements may be useful in monitoring adherence to AZT-containing regimens.