bluuebunny/crossref_metadata_2025 huggingface dataset:
Análise comparativa dos efeitos do ultrassom terapêutico e laser de baixa potência sobre a proliferação de células musculares durante a diferenciação celular
Authors: Artilheiro Paola Pelegrineli , Barbosa Jean Lucas Parpinelli , Fernandes Kristianne Porta Santos , Oliveira Tábata Santos de , Bussadori Sandra Kalil , Mesquita-Ferrari Raquel Agnelli
Published: June 2012

INTRODUÇÃO: Existe um grande interesse no estabelecimento de recursos e terapias a serem utilizados na tentativa de proporcionar um processo de reparo muscular de melhor qualidade e menor duração. O ultrassom terapêutico (US) e o laser de baixa potência (LBP) são recursos muito usados na prática clínica, porém são escassas, e por vezes contraditórias, as evidências científicas que determinam com segurança os parâmetros dosimétricos e metodológicos adequados. OBJETIVOS: O objetivo do estudo foi analisar o efeito do US e do LBP sobre a proliferação celular durante a diferenciação de mioblastos C2C12. MATERIAIS E MÉTODOS: Os mioblastos foram cultivados em meio de cultura de Eagle modificado por Dulbecco, contendo 10% de soro fetal bovino (SFB), sendo induzida a diferenciação pela adição de 2% de soro de cavalo durante 96 horas. Posteriormente, as células foram irradiadas com US pulsado a 20%, 3 MHz de frequência (intensidades de 0,2 e 0,5 W/cm², durante cinco minutos) ou submetidas ao tratamento com LBP (potência de saída de 10 mW, densidade de energia de 3 e 5 J/cm², por 20 segundos). A proliferação celular foi avaliada após 24h e 72h utilizando o método de MTT. Foram realizados três experimentos independentes, em cada condição citada e células não irradiadas serviram como controle. RESULTADOS: Os resultados obtidos foram submetidos à análise estatística utilizando a Análise de Variância (ANOVA), teste Dunnet, para verificar diferenças entre o grupo controle (não tratado) e os grupos tratados com US e LBP, adotando significância de p < 0,05. Os resultados evidenciaram que não houve diferença significativa na proliferação celular entre as células musculares submetidas a tratamento com ambos os recursos terapêuticos e as células controle, nos períodos de 24h e 72h após tratamento. Além disso, foi possível verificar que não houve aumento significativo no número de células após o período de 72h quando comparado a 24h, confirmando o processo de diferenciação celular, conforme esperado. CONCLUSÕES: Conclui-se que o US e o LBP, nos parâmetros avaliados, não alteraram a proliferação de mioblastos em processo de diferenciação.
Abandoned coal mine drainage and its remediation: impacts on stream ecosystem structure and function
Authors: Bott Thomas L. , Jackson John K. , McTammany Matthew E. , Newbold J. Denis , Rier Steven T. , Sweeney Bernard W. , Battle Juliann M.
Published: June 2012

The effects of abandoned mine drainage (AMD) on streams and responses to remediation efforts were studied using three streams (AMD‐impacted, remediated, reference) in both the anthracite and the bituminous coal mining regions of Pennsylvania (USA). Response variables included ecosystem function as well as water chemistry and macroinvertebrate community composition. The bituminous AMD stream was extremely acidic with high dissolved metals concentrations, a prolific mid‐summer growth of the filamentous alga, Mougeotia, and >10‐fold more chlorophyll than the reference stream. The anthracite AMD stream had a higher pH, substrata coated with iron hydroxide(s), and negligible chlorophyll. Macroinvertebrate communities in the AMD streams were different from the reference streams, the remediated streams, and each other. Relative to the reference stream, the AMD stream(s) had (1) greater gross primary productivity (GPP) in the bituminous region and undetectable GPP in the anthracite region, (2) greater ecosystem respiration in both regions, (3) greatly reduced ammonium uptake and nitrification in both regions, (4) lower nitrate uptake in the bituminous (but not the anthracite) region, (5) more rapid phosphorus removal from the water column in both regions, (6) activities of phosphorus‐acquiring, nitrogen‐acquiring, and hydrolytic‐carbon‐acquiring enzymes that indicated extreme phosphorus limitation in both regions, and (7) slower oak and maple leaf decomposition in the bituminous region and slower oak decomposition in the anthracite region. Remediation brought chlorophyll concentrations and GPP nearer to values for respective reference streams, depressed ecosystem respiration, restored ammonium uptake, and partially restored nitrification in the bituminous (but not the anthracite) region, reduced nitrate uptake to an undetectable level, restored phosphorus uptake to near normal rates, and brought enzyme activities more in line with the reference stream in the bituminous (but not the anthracite) region. Denitrification was not detected in any stream. Water chemistry and macroinvertebrate community structure analyses capture the impact of AMD at the local reach scale, but functional measures revealed that AMD has ramifications that can cascade to downstream reaches and perhaps to receiving estuaries.
Does the Age of Offenders and Victims in Crime Scenarios Affect Perceptions of Crime Seriousness and Punitiveness Among Students?
Authors: Bensimon Moshe , Bodner Ehud
Published: June 2012

The extent to which the age of the offender or the victim influences respondents’ respective evaluations of crime seriousness and punitiveness has rarely been studied. This study hypothesizes that evaluations of the severity of offenses with intrapersonal and interpersonal social implications and the estimation of their punitiveness will be more serious when the offenses are performed by younger than by older offenders and less serious when they harm younger as opposed to older victims. Results from 129 undergraduate students who were administered the Multidimensional Social Transgressions Scale (MSTS) confirm the hypotheses. The findings are discussed in light of crime theories, social theories, and ageism studies.
Workplace Bullying, Emotions, and Outcomes
Authors: Glasø Lars , Notelaers Guy
Published: June 2012

This study examines emotional experiences as potential mediators between exposure to workplace bullying and job satisfaction, organizational commitment, and intention to leave the organization, respectively. A total of 5,520 respondents participated in the study. Drawing upon affective events theory (AET), the results show that emotions partly mediate these relationships and, hence, support the notion that emotions play a central part in the relationship between bullying and essential occupational outcomes.
Multidimensional Self-Esteem as a Mediator of the Relationship Between Sports Participation and Victimization: A Study of African American Girls
Authors: Taylor Matthew J. , Wamser Rachel A. , Welch Desiree Z. , Nanney John T.
Published: June 2012

The purpose of this study that focused on African American high school girls was threefold. First, the relationship of sports participation and victimization was explored. Second, the impact of sports participation on self-esteem was assessed. Third, the role of self-esteem and its disaggregated components (social acceptance, competence, and self-confidence) as mediators of the relationship between sports participation and victimization was examined. In accordance with the sport protection hypothesis, it was hypothesized that sports participation would be related to enhanced self-esteem and reduce victimization. Results suggest that sports participation appears to have some relationship to lower rates of victimization. There was also support for our assertion that sports participation was related to enhanced self-esteem. Finally, overall self-esteem and, specifically, the individual component competence mediated the relationship between sports participation and victimization.
Guided Bone Regeneration Using Injectable Vascular Endothelial Growth Factor Delivery Gel
Authors: Kaigler Darnell , Silva Eduardo A. , Mooney David J.
Published: June 2012

Background: Vascularization underlies the success of guided bone regeneration (GBR) procedures. This study evaluates the regenerative potential of GBR in combination with vascular endothelial growth factor (VEGF) delivery via an injectable hydrogel system.

Methods: Critical‐sized defects were created in rat calvariae, and GBR procedures were performed with a collagen membrane alone (control), or plus bolus delivery of VEGF, or plus application of VEGF‐releasing hydrogels (VEGF–Alg). Four and 8 weeks after treatment, defect sites were evaluated with microcomputed tomographic and histomorphometric analyses for blood vessel and bone formation.

Results: At 4 weeks, relative to the control condition, the bolus addition of VEGF did not affect blood vessel density within the defect site, yet the application of VEGF–Alg significantly (P <0.05) increased blood vessel density. Although there was no difference in bone regeneration at 4 weeks, at 8 weeks there was a significant (P <0.05) increase in bone regeneration in the VEGF–Alg‐treated defects.

Conclusions: These data demonstrate that the application of VEGF–Alg enhanced early angiogenesis, whereas at a later time point, it enhanced bone regeneration. Controlled delivery approaches of angiogenic growth factors used adjunctively with GBR may be a promising strategy for enhancing outcomes of GBR.
Latex-Based Cement Design: Meeting the Challenges of the Haynesville Shale
Authors: Pavlock Cole , Tennison Brad , Thompson Jonn , Darbe Robert
Published: June 2012

The Haynesville shale presents special challenges when designing cement systems. Extended-reach, horizontal wellbores create a high-pressure/high-temperature (HP/HT) environment not conducive to conventional cement slurries. Tight annular clearances and a narrow pore-pressure/fracture-gradient window have forced the industry to push the boundaries of cementing theory. Cement designs with a latex additive have improved rheological characteristics that yield lower equivalent circulating densities (ECDs) and reduce the frictional coefficient necessary for manageable surface pressures. The latex-based designs are thermally stable up to 400°F and provide excellent fluid-loss control, while still improving surface mixability. Most of the desired properties are observed when the cement is liquid; the set cement sheath can also provide corrosion resistance, annular bonding, and elasticity for well cycling.

The development, testing, and case histories of latex-based cement slurries are discussed in this paper and compared to conventional cement designs for horizontal applications. By improving the physical properties of the cement while it is still in a fluid state, the cement can be properly placed, thus decreasing the potential for job failures. With the fluid viscosities enhanced, the pump rates can be optimized using hydraulic modeling to obtain increased mud-displacement efficiency. Laboratory testing has shown the latex additive to be effective from 1 to 2.5 gal per sack of cement. The latex additive enhances several cementing properties and reduces the need for additional fluid modifiers. By reducing the additives in the blend, the testing variability is decreased and repeatability is increased. Similar designs have been used in the past, but failure to maintain system stability created limitations. With new technology and theory, a heavyweight, thermally stable cement can be pumped during the most adverse well conditions.
Evaluation of Precompletion Annular Gas Leaks in a Marcellus Lateral
Authors: Moore L. P. , Jones J. E. , Perlman S. H. , Huey T. A.
Published: June 2012

Environmental concerns in Pennsylvania related to Marcellus Shale development are high. One of the issues to which the Pennsylvania Department of Environmental Protection (PADEP) has given a high priority is the threat of methane migration into fresh water as a result of methane leaking to surface from behind casing. This has become a significant problem for Marcellus operators as leaking annuli on both new and existing wells is not uncommon. This paper outlines the steps that Flatirons Development took to demonstrate to PADEP that the annular leaks on a recently drilled and cased Marcellus lateral posed no credible threat to ground water and that completion of the well should be allowed to proceed.

In early June, 2011, Flatirons became aware of bubbling in the water filled cellar of the DU 3-6-1H. This discovery came just as completion operations were set to begin. Subsequent investigation revealed that there were two leaks, one from the production-intermediate annulus and another very small leak from the intermediate-surface annulus. PADEP issued Flatirons a Notice of Violation (NOV) and requested that fracture treating the well not proceed until the issue had been resolved.

Over the following two months, Flatirons implemented a series of diagnostic procedures meant to assess the short and long term environmental threat, determine the cause of the problem, trace the source of the gas, and, if necessary, formulate effective remediation options. Using a variety of tools including ultrasonic imaging, pressure build-ups, noise-temperature logs, gas isotopic analysis, cement sample analysis, and continuous monitoring of annular flow, Flatirons was able to demonstrate that the fresh water aquifer was not threatened by methane migration. This work was presented to PADEP's Gas Well Integrity study group and helped form a basis for revising regulations governing leaking annuli.
Establishing Key Reservoir Parameters with Diagnostic Fracture Injection Testing
Authors: Nojabaei B. , Kabir C. S.
Published: June 2012

Diagnostic fracture injection testing (DFIT) is an invaluable tool for evaluating reservoir properties in unconventional formations. The test comprises injection of water over a very short time period, initiating a fracture at the end of a well's horizontal section, followed by a long shut-in period. Analysis of the falloff data with the G-function plot reveals the fracture closure pressure, and the fracture pseudolinear-flow period leads to the initial reservoir pressure.

In most tests, wellhead pressure (WHP) measurements are used because of cost considerations. A wellbore heat transfer model is used to allow conversion of WHP to bottomhole pressure (BHP) by accounting for changing fluid density and compressibility along the wellbore. This model, in turn, allowed us to assess the quality of solutions generated with the WHP data. For DFIT analysis, we adapted the modified-Hall plot for the injection period, whereas both the pressure-derivative and G-function plots were used for the analysis of falloff data. The derivative signature of the modified-Hall plot allows unambiguous estimation of the fracture breakdown pressure (pfb) during the injection period. As expected, the pfb always turns out to be higher than the fracture closure pressure (pfc), estimated with the two methods during pressure falloff, thereby instilling confidence in the solutions obtained.

A statistical design of experiments with coupled geomechanical/fluid-flow simulation capabilities showed that the formation permeability is by far the most important variable controlling the fracture closure time. Mechanical rock properties, such as Young's modulus of elasticity and the Poisson's ratio, play minor roles. In microdarcy formations, a longitudinal fracture takes much longer to close than its transverse counterpart.
Novel Water-base Mud for Shale Gas, Part II: Mud Formulations and Performances
Authors: Riley Meghan , Stamatakis Emanuel , Young Steve , Price Hoelscher Katherine , Stefano Guido De
Published: June 2012

Shale-gas plays and other unconventional resources have gained significant importance worldwide. Historically, synthetic based drilling fluids (SBM) are used in these plays when no environmental concerns are in place and are preferred when wellbore stability is necessary. In this paper, we study the use of an improved water based drilling fluid (WBM) that is simple in formulation and maintenance that shows excellent rheological properties, maintains wellbore stability, and a good environmental profile. A combination of well-known and economically affordable materials is combined with new technology to achieve desired rheological properties and wellbore stability.

The use of nanoparticles to decrease shale permeability by physically plugging nanoscale pores holds the potential to remove a major hurdle in confidently applying water-based drilling fluids in shale formations, adding a new advantage to the studied fluid. Silica nanomaterials were investigated for this purpose. Due to their commercial availability, these materials can be engineered to meet the specifications of the formation. Characterization of the nanoparticles was completed with Transmission Electron Microscopy (TEM), dynamic light scattering, and X-ray-photoelectron spectroscopy. Rheological properties and fluid loss are studied together with other important properties such as shale stability and anti-accretion properties. The authors will describe new laboratory methods used to investigate these properties, from a modified API fluid loss test to the Shale Membrane Test that measures both fluid loss and plugging effects and illustrate additional future research that includes adding reactive species, and anchoring them to the pores, thus stabilizing the shale further.
Integrated Unconventional Shale Gas Reservoir Modeling: A Worked Example From the Haynesville Shale, De Soto Parish, North Lousiana.
Authors: Díaz de Souza O. C. , Sharp A. J. , Martinez R. C. , Foster R. A. , Simpson M. Reeves , Piekenbrock E. J. , Abou-Sayed I.
Published: June 2012

Production from shale gas reservoirs in the USA has become an important component in the increase of natural gas supply. The Haynesville shale, in particular, is a major contributor in gas supply due mainly to its relatively higher initial deliverability compared to other gas shale plays.

One of the critical questions in developing a play efficiently and economically is the well spacing. There are several approaches to addressing this question. The paper looks at one approach, namely the process behind building a calibrated, history matched multi well reservoir model. The model is run in prediction mode with different sensitivities to answer the well spacing issue. The model honors the initial static and dynamic conditions, is capable of running in a reasonable time and, most importantly, has been useful to management in the decision making process.

In this field case, a half section in the state of Louisiana has been drilled and completed with 4 horizontal multistage producing wells and 2 vertical microseismic monitoring wells, 1 of which was subsequently converted to a downhole pressure monitoring well. During the entire hydraulic fracturing operation, downhole microseismic data were simultaneously recorded in both observation wells. The pressure data from the monitor well acquired during production was entered into the reservoir model as another history matching variable. The microseismic data were used to calculate the fracture parameters and as a limiting constraint in the process. This dual porosity model is a practical example application of the methodology previously described in SPE paper 132180 by Du et al. (2010).

The sections in this paper describe a method for building a reservoir model that honors the static boundary conditions. The model was built in two parts according to the Dual Porosity nature of it: a conventional geological model representing the initial porosity and permeability of the rock matrix, and a second part that models the fracture network generated by the stimulation operations and the pre-existing natural fractures. The paper then explains how this model was tuned to enable a production and pressure history match. There is also a section devoted to the generation and utilization of a critical correlation between pressure depletion and a combined fracture half-length times the square root of permeability (Xf.√k) parameter which greatly reduced the uncertainty caused by the non-uniqueness of the match. Finally, some general conclusions regarding the results are presented.
Hybrid Drill Bit Combining Fixed-Cutter and Roller-Cone Elements Improves Drilling Performance in Marcellus Shale Surface Interval
Authors: Bradford John , Ferrari Anthony , Rickabaugh Caleb , Rothe Mitchell , Tipton Brent
Published: June 2012

The application of hybrid bits saves the operator drilling time by out-drilling conventional roller-cone and fixed-cutter bits in the difficult Marcellus shale surface interval. This interval comprises interbedded sandstone, shale, and siltstone down to 600-1,200 ft. deep. Historically, hammer bits and air have been used to drill the surface interval resulting in high penetration rates. In today's environmentally conscious oil industry, some operators have changed casing profiles to better protect water zones and switched to drilling with mud instead of air. Operators drilling these overbalanced wells typically use conventional roller-cone and fixed-cutter bits depending on the area of the play. The roller-cone bits consistently drill the entire interval, yet achieve slow penetration rates due to the lack of available weight. Fixed-cutter bits have been tested to achieve higher penetration rates. They drill faster than roller-cone bits with the available weight on bit, but are accompanied by dynamic dysfunction that leads to a poor dull condition and seldom complete the entire interval.

Extensive research, testing, and development have produced a hybrid bit combining roller-cone and fixed-cutter elements to address these major challenges. The fixed-cutter elements help provide higher penetration rates with the low available weight on bit. The roller-cone cutting elements help drill through the harder part of the interbedded formation by reducing drilling dysfunctions while maintaining a better dull condition.

This paper is a case study comparing the performance of roller-cone, fixed-cutter, and hybrid bits using field results and drilling data from an operator's Marcellus shale surface interval.
Natural Fracture Identification and Characterization While Drilling Underbalanced
Authors: Norbeck Jack , Fonseca Ernesto , Griffiths D. V. , Wong Sau-Wai
Published: June 2012

An algorithm based on data obtained during underbalanced drilling operations is described for identifying the location and properties of productive natural fractures that are intersected by the wellbore. The criteria used to identify natural fracture locations are (i) total gas concentration measurements from mud logs and (ii) mud pit volume. The paper also describes a simple approach for estimating the fracture permeability. The algorithm is applied to data from three sets of horizontal parallel wells with spacing of roughly 700 ft. In two of the three well pairs considered, conductive fracture locations identified in one well aligned with corresponding features in the parallel well. An attraction of the proposed methodology is that it makes use of data that is commonly recorded during drilling, reducing the need for expensive image log tests. The information obtained from this type of analysis can be used to improve hydraulic fracture treatment designs.
Numerical Simulation of Enhanced Oil Recovery in the Middle Bakken and Upper Three Forks Tight Oil Reservoirs of the Williston Basin
Authors: Iwere F. O. , Heim Robin N. , Cherian B. V.
Published: June 2012

The United States Geologic Survey (USGS) reported in 2008 that undiscovered technically recoverable oil in the Bakken was about 3.6 billion barrels across the U.S. portion of the basin, considering recent successful application of horizontal wells and multistage hydraulic fracturing technologies. As the development of the unconventional resources in the Williston Basin continues beyond the phases of exploration and lease evaluation, optimum well spacing and recovery factor will become forefront considerations in the formulation of asset development strategies. Based on our studies the reservoir producing mechanism is primarily solution gas drive and primary oil recovery factor is lower than 15% of the original oil in-place. This low recovery or very high oil volume remaining in place is a strong motivation to investigate the application of enhanced oil recovery methods in this basin.

This paper describes the construction of numerical simulation models using typical fluid and rock properties for the Bakken and Three Forks, assuming both naturally fractured and single porosity systems and their combinations. Multistage hydraulic fracture properties are determined from well completion engineering and coupled with the flow models. The flow models are constrained by well operating practices implemented by operators across the basin during primary oil production. The results of pressure maintenance methods to arrest the rapid reservoir pressure decline due to large pressure drawdown necessary to produce oil and water, as well as gas (including carbon dioxide) and water injection methods to improve oil recovery are presented.
Quantification of Fracturing Fluid Migration due to Spontaneous Imbibition in Fractured Tight Formations
Authors: Dutta R. , Lee C.-H. , Odumabo S. , Ye P. , Walker S. C. , Karpyn Z. T. , Ayala L. F.
Published: June 2012

During hydraulic fracturing operations in low permeability formations, spontaneous imbibition of fracturing fluid into the rock matrix may be responsible for having a significant impact on the retention of water-based fracturing fluids in the neighborhood of the induced fracture. This may consequently affect the post-frac productivity of the well. However, there is lack of direct quantitative and visual evidence of the extent of retention, evolution of the resulting imbibing fluid front, and how they relate to potential productivity hindrance. In this paper, laboratory experiments have been carefully designed to represent the vicinity of a hydraulic fracture. The evolution of fracturing fluid leak-off is monitored as a function of space and time using X-ray computed tomography (CT). The X-ray CT imaging technique allows us to map saturations at controlled time intervals to monitor the migration of fracturing fluid into the reservoir formation. It is generally expected for low permeability formations to show strong capillary forces due to their small characteristic pore radii, but this driving mechanism is in competition with the low permeability and spatial heterogeneities found in tight gas sands. The relevance of capillarity as a driver of fluid migration and retention in a tight gas sand sample is interpreted visually, quantified and compared with high permeability Berea sandstone in our experiments. It is seen that although these formations demonstrate strong capillarity, the effect can be suppressed by the low permeability of the formation and the heterogeneous nature of the sample. However, saturation values attained during imbibition experiments are comparable to those previously obtained for high permeability samples, which can have significant implications in terms of phase mobilities in the neighborhood of induced fractures. Results from this investigation are expected to provide fundamental insight regarding critical variables affecting the retention and migration of water-based fracturing fluids in the neighborhood of hydraulic fractures, and consequently on the post-frac productivity of the well.
Improved Methodologies for More Accurate Shale Gas Assessments
Authors: Boulis Anastasios , Jayakumar Ramkumar , Lalehrokh Farshad , Lawal Hamed
Published: June 2012

Over the last few decades, shale gas has become an increasingly important global source of natural gas, especially in the United States. According to Polczer (2009) and Krauss (2009), shale gas will greatly expand worldwide and is expected to supply as much as half the natural gas production in North America by 2020. Due to extremely low shale matrix permeability, shale is considered an unconventional source of gas and requires fractures to provide a flow path to the wellbore. Due to uncertainties in quantifying the gas-in-place and identifying flow behavior; estimating the ultimate recoveries in shale gas reservoirs requires new techniques. In this paper, we used four approaches to estimate the ultimate recovery in shale gas wells: two empirical methods (conventional and modified decline curve analysis), analytical modeling and numerical modeling. All four approaches were applied on wells from four different shale plays (Barnett, Haynesville, Marcellus and Woodford).
Designing Completions in Horizontal Shale Gas Wells - Perforation Strategies
Authors: Wutherich Kevin D. , Walker Kirby J.
Published: June 2012

Horizontal cased hole completions have become the accepted practice for completing wells in many shale gas plays. There has been a great deal of focus on how to optimize these completions. One of the most important, yet least discussed, concepts in horizontal shale completion optimization strategies is how to perforate to optimize for both placement efficiency of the hydraulic fracture treatment as well as production.

Some of the perforation scheme characteristics that typically need consideration are as follows:The number of perforation clusters for each fracture stageThe optimum number of perforations per clusterThe distance between perforation clustersThe length of each perforated intervalShot density, phasing and perforation charge typeOptimal location to place the clusters

Taking into account all of these considerations and using an optimized perforation strategy can be the difference between placing a fracture as per design or experiencing high treatment pressures throughout the stimulation treatment and prematurely aborting the job part way through. Even more importantly, properly engineered perforations can improve overall production by ensuring an equal fracture treatment through each perforation cluster as well as improving wellbore connectivity to the fracture.

This paper looks at all these outlined aspects through a number of different means including a literature review, the use of simulation tools, and case studies from the Marcellus shale. Ultimately, a strategy for optimized perforations is presented with specific focus on shale gas horizontal wells in the Marcellus with further application to other shale gas plays.
Nanopore Structure Analysis and Permeability Predictions for a Tight Gas/Shale Reservoir Using Low-Pressure Adsorption and Mercury Intrusion Techniques
Authors: Clarkson C. R. , Wood J. M. , Burgis S. E. , Aquino S. D. , Freeman M. , Birss V.
Published: June 2012

The pore structure of unconventional gas reservoirs, despite having a significant impact on hydrocarbon storage and transport, has historically been difficult to characterize due to a wide pore size distribution, with a significant pore volume in the nanopore range. A variety of methods are typically required to characterize the full pore spectrum, with each individual technique limited to a certain pore size range.

In this work, we investigate the use of non-destructive, low-pressure adsorption methods, in particular low pressure N2 adsorption analysis, to infer pore shape, and to determine pore size distributions of a tight gas/shale reservoir in Western Canada. Unlike previous studies, core plug samples, not crushed samples, are used for isotherm analysis, allowing an undisturbed pore structure to be analyzed. Further, the core plugs used for isotherm analysis are subsamples (end pieces) of cores for which MICP and permeability measurements were previously made, allowing a more direct comparison with these techniques. Pore size distributions determined from two isotherm interpretation methods (BJH Theory and Density Functional Theory), are in reasonable agreement with MICP, for that portion of the pore size distribution sampled by both. The pore geometry is interpreted to be slit-shaped, as inferred from isotherm hysteresis loop shape, the agreement between adsorption- and MICP-derived dominant pore sizes, SEM imaging and the character of measured permeability stress-dependence. Although correlations between inorganic composition and total organic carbon (TOC) and dominant pore throat size and permeability are weak, the sample with the lowest illite clay and TOC content has the largest dominant pore throat size and highest permeability, as estimated from MICP. The presence of stress-relief-induced microfractures, however, appears to affect lab-derived (pressure-decay and pulse-decay) estimates of permeability, even after application of confining pressure.

Based on the premise of slit-shaped pore geometry, fractured rock models (matchstick and cube) were used to predict absolute permeability, using dominant pore throat size from MICP/adsorption analysis and porosity measured under confining pressure. The predictions are reasonable, although permeability is mostly over-predicted for samples that are unaffected by stress-release fractures. The conceptual model used to justify the application of these models is slot pores at grain boundaries.
Production Data Analysis in Unconventional Reservoirs with Rate-Normalized Pressure (RNP): Theory, Methodology, and Applications
Authors: Samandarli Orkhan , Valbuena Ernesto , Ehlig-Economides Christine
Published: June 2012

Unconventional reservoirs, shale gas and oil for instance, have proven to be an important contributor to hydrocarbon production in North America. Horizontal wells with multiple transverse fractures unlocked these unconventional resources by attaining profitable production rates and increasing gas reserves for future years. A critical challenge in these types of reservoirs is characterizing the stimulated reservoir volume (SRV), by estimating the effective productive volume created during stimulation and quantifying the permeability of the formation.

Recent approaches for rate and pressure data deconvolution have emphasized the benefits of using buildup responses acquired whenever the well is shut-in, often for operational reasons, to assess significant insights about heterogeneity and compartmentalization in conventional reservoirs. However, deconvolution performs poorly when the initial reservoir pressure is unknown and might generate ambiguous results when pressure data accuracy is questionable.

Regular measurements of daily production rates and wellhead flowing pressures can provide important information about well completion, stimulation, and formation parameters. With effective data processing, rate-normalized pressure (RNP) converts variable-rate and variable-pressure data to an equivalent of the drawdown pressure response to constant-rate production. This reveals flow regimes that enable direct estimation of the formation permeability and the productive fracture extent in the SRV. Subsequently, observed field rates and pressures can be matched with a global model to refine the estimates from the flow regime analysis. Although numerical models can be used to match the data, in this study we employed an analytical flow regime equations that provides fast and accurate results that can be easily programmed.

The proposed methodology was applied to production data from Barnett shale wells providing excellent results and demonstrating an efficient, fast, and cost effective method to estimate critical well and formation parameters in unconventional reservoirs. The same methodology can be used to diagnose wells from other unconventional resources.
Field Development Study: Channel Fracturing Achieves Both Operational and Productivity Goals in the Barnett Shale
Authors: Samuelson M. , Stefanski J. , Downie R. , Mikhaylov A. , Ovsyannikov D. , Peña A.
Published: June 2012

The Barnett shale has an extensive history of various hydraulic fracture methodologies aimed at creating both reservoir connection via complex fracture networks and a conductive proppant pack for fluid flow to the wellbore. Multiple studies indicate that effective stimulation of shale plays like the Barnett shale require extensive conductive complex fracture development coupled with sufficient proppant-pack retained permeability to maximize well productivity. Studies have also shown that wells very often underperform expectations after the application of low proppant concentrations with slickwater fluids and/or hybrid designs with linear or crosslinked fluids. Furthermore, recent increased restrictions on fracturing operations in urban areas have created a need to reduce the operational footprint of the treatments without compromising production results. The need exists for novel stimulation methods capable of addressing these challenges.

The channel hydraulic fracturing technique creates open pathways within the proppant pack by combining specific surface equipment controls and pumping protocols with fluid and fiber technologies. The engineered network of channels provides highly conductive paths for the flow of fluids from the reservoir to the wellbore.

We conducted a study including more than 50 treatments performed in the Barnett shale with this technique. These treatments reduced proppant and water used per well up to 40% and 36%, respectively, compared to treatments with conventional methods in offset wells. The study includes the use of advanced modeling software, coupled with microseismic evaluation and comparison of conventional job designs with the channel-fracturing approach, to evaluate the impact on fracture geometry.

The results of the study indicate that the channel fracturing technique increased operational efficiency at equivalent well production in the study area of the Barnett shale. Microseismic comparisons show similar fracture heights and transverse fracture lengths. Coupling of conventional higher rate slickwater treatments with the channel fracturing technique yields equivalent well production while achieving significant reductions in fluid and proppant used in the job designs. The project demonstrated that such reductions have led to more than 38 million gallons of water and over 3,000 proppant and water-hauling trips saved for every 50 stages using this technology for the stimulation of wells in the Barnett shale.
A Pore Scale Gas Flow Model for Shale Gas Reservoir
Authors: Swami Vivek , Settari A. (Tony)
Published: June 2012

It has been observed that the shale gas production modeled with conventional simulators/models is much lower than actually observed field data. Generally reservoir and/or stimulated reservoir volume (SRV) parameters are modified (without much physical support) to match production data. One of the important parameters controlling flow is the effective permeability of the intact shale. In this project we aim to model flow in shale nano pores by capturing the physics behind the actual process. For the flow dynamics, in addition to Darcy flow, the effects of slippage at the boundary of pores and Knudsen diffusion have been included. For the gas source, the compressed gas stored in pore spaces, gas adsorbed at pore walls and gas diffusing from the kerogen have been considered. To imitate the actual scenario, real gas has been considered to model the flow. Partial differential equations were derived capturing the physics and finite difference method was used to solve the coupled differential equations numerically. The contribution of Knudsen diffusion and gas slippage, gas desorption and gas diffusion from kerogen to total production was studied in detail. It was seen that including the additional physics causes significant differences in pressure gradients and increases cumulative production. We conclude that the above effects should be considered while modeling and making production forecasts for shale gas reservoirs.
Effect of Capillary Relaxation on Water Entrapment after Hydraulic Fracturing Stimulation
Authors: Michel G. , Sigal R. , Civan F. , Devegowda D.
Published: June 2012

Effect of retardation in fluid displacement on transport inside capillary tubes during leak-off and clean-up for hydraulically stimulated reservoirs is investigated by modeling of the relevant phenomena. The effect of wall proximity during the transport in narrow capillaries is formulated. The importance of the critical properties alteration due to confinement is demonstrated by modification of the real gas deviation factor. The relaxation in fluid displacement observed in the fluid transport dynamics is coupled with the bundle of tubes representation of porous media for investigation of the relaxation effects on fluid saturation, capillary pressure, and relative permeability. An analytical formulation of the relaxation time corresponding to water removal during clean-up processes following hydraulic fracture stimulation is presented. The dynamics of advancement of the wetting and non-wetting fluids inside capillary tubes are illustrated by various applications.
Formal and Informal Help-Seeking for Mental Health Problems. A Survey
of Preferences of Italian Students
Authors: D’Avanzo Barbara , Barbato Angelo , Erzegovesi Stefano , Lampertico Letizia , Rapisarda Filippo , Valsecchi Lella
Published: June 2012

Help-seeking preferences for mental health are a crucial aspect to design strategies to support adolescents in an emotionally delicate life phase. Informal help-seeking is usually preferred but little was published about preferences in different cultures, and it is not clear whether informal and formal help are mutually exclusive or whether they are part of the same overall propensity to help-seeking. In a survey of 710 students in Milan, Italy, help-seeking propensity measured through an Italian version of the General Help-Seeking Questionnaire was high, similar in males and females (mean total score 3.8, DS 0.9); few (9%) tended not to seek help. The most-preferred source of help was a friend, then father or mother, partner, psychologist and psychiatrist. 355 students (55%) reported high propensity to seek both informal and formal help; 33 (5%) would only seek formal help. Help-seeking should be promoted in itself, rather than indicating professionals and professional settings as primary sources of help.
Marijuana: Modern Medical Chimaera
Authors: Lamarine Roland J.
Published: June 2012

Marijuana has been used medically since antiquity. In recent years there has been a resurgence of interest in medical applications of various cannabis preparations. These drugs have been cited in the medical literature as potential secondary treatment agents for severe pain, muscle spasticity, anorexia, nausea, sleep disturbances, and numerous other uses. This article reviews the research literature related to medical applications of various forms of cannabis. Benefits related to medical use of cannabinoids are examined and a number of potential risks associated with cannabis use, both medical and recreational, are considered. There is a clearly identified need for further research to isolate significant benefits from the medical application of cannabinoids and to establish dosage levels, appropriate delivery mechanisms and formulations, and to determine what role, if any, cannabinoids might play in legitimate medical applications. It is also imperative to determine if reported dangers pose a significant health risks to users.
What If You Caught Them Using? Prospective Teachers' Beliefs about Responding to Student Substance Use
Authors: Ludden Alison Bryant
Published: June 2012

This survey research examined how prospective teachers' ( N = 384) beliefs about the nature of adolescence, their substance use, and their preparedness for dealing with substance use situations are linked to perceptions of how they would respond to students' possession or use of cigarettes, alcohol, and marijuana at school. Results suggested that prospective teachers are not prepared for these situations. Feeling prepared, perceiving that few adolescents engage in problem behavior, and low personal substance use were associated with more responses to substance use situations. Women were more likely than men to think they would respond to adolescent substance use yet they felt less prepared. Males who used alcohol, cigarettes, or marijuana recently were the least likely to perceive that they would respond to adolescents using substances at school.
Starting to Drink: The Experiences of Australian Lower Secondary Students with Alcohol
Authors: Davenport Gillian , Midford Richard , Ramsden Robyn , Cahill Helen , Venning Lynne , Lester Leanne , Murphy Bernadette , Pose Michelle
Published: June 2012

This study describes Australian year eight students' (13–14 years old) experiences with alcohol in terms of communication with parents, initiation into drinking, patterns of consumption, context of use, and harms experienced. The sample comprised 521 year eight students from four state government secondary schools in the state of Victoria. Three of the schools are in Melbourne, the capital of Victoria; the fourth is in a rural center. Female and rural students were more likely to talk to parents about alcohol, but this was not associated with safer drinking. Initiation into drinking was higher among rural students. Rural students also drank more, were more likely to drink without adult supervision, to drink to get drunk, and drink more than planned. Student drinkers experienced just over four alcohol-related harms on average in 12 months, with some indication of greater harm among rural students. Higher levels of drinking by rural students, accompanied by more risky patterns of consumption and the possibility of greater harm, supports prioritizing interventions in rural schools.
“A Sound Track of Your Life”: Music in Contemporary Uk Funerals
Authors: Adamson Sue , Holloway Margaret
Published: June 2012

This article considers the role that music plays in contemporary UK funerals and the meaning that the funeral music has for bereaved families. It is based on findings from a recently completed study of 46 funerals funded by the UK Arts and Humanities Research Council. Music contributes to the public ceremony and the personal existential quest of the bereaved. It is important to both the content and process of the contemporary funeral, an event of deep cultural significance in our response as individuals and communities to death and the loss of a significant relationship. There is evidence that for many people, the music chosen and used also evokes and conveys their spirituality. Spirituality may not be intrinsic to the music but spiritual experience may result from the meaning that the music has for that particular person.
Conversations, Coping, & Connectedness: A Qualitative Study of Women Who Have Experienced Involuntary Pregnancy Loss
Authors: Van Paulina
Published: June 2012

The purpose of this qualitative study was to describe processes and strategies used by women to cope after pregnancy loss. Twenty women with a history of involuntary pregnancy loss were interviewed. All of the women were in the last month of a subsequent pregnancy, married or partnered, and most were EuroAmerican or Asian American and had completed college. Taped interviews, fieldnotes, and analytical notes were transcribed then subsequently coded and developed in individual or team sessions. Construction and confirmation of the categories and related themes derived from the data was a collaborative process. Three themes were revealed that described the coping behaviors used by the women: being myself, connecting with others, and avoiding and pretending. The core concept of connectedness and coping after involuntary pregnancy loss was further validated in this study. The purpose of this study was to describe processes and strategies that facilitate coping for 20 women, pregnant subsequent to an involuntary pregnancy loss (IPL). Involuntary pregnancy loss (IPL) refers to miscarriages, ectopic pregnancies, fetal deaths, and stillbirths (Van & Meleis, 2003). This current study was designed to replicate two prior qualitative studies, with African-American women, by the author (Patterson, 2000; Van, 2001). Based on the author's previous work, a theoretical framework entitled “A Model of Living with Grief after Pregnancy Loss” was constructed (Patterson, 2000). For the current study, a more diverse sample was used to potentially expand the applicability of the Model of Living with Grief after Pregnancy Loss to women who are of races other than African American.