bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Variation and Covariation in Male Attractiveness and Female Mating Preferences inDrosophila melanogaster
Authors: Ratterman Nicholas L , Rosenthal Gil G , Carney Ginger E , Jones Adam G
Published: November 2013

How mating preferences evolve remains one of the major unsolved mysteries in evolutionary biology. One major impediment to the study of ornament-preference coevolution is that many aspects of the theoretical literature remain loosely connected to empirical data. Theoretical models typically streamline mating preferences by describing preference functions with a single parameter, a modeling convenience that may veil important aspects of preference evolution. Here, we use a high-throughput behavioral assay in Drosophila melanogaster to quantify attractiveness and multiple components of preferences in both males and females. Females varied genetically with respect to how they ranked males in terms of attractiveness as well as the extent to which they discriminated among different males. Conversely, males showed consistent preferences for females, suggesting that D. melanogaster males tend to rank different female phenotypes in the same order in terms of attractiveness. Moreover, we reveal a heretofore undocumented positive genetic correlation between male attractiveness and female choosiness, which is a measure of the variability in a female’s response to different male phenotypes. This genetic correlation sets the stage for female choosiness to evolve via a correlated response to selection on male traits and potentially adds a new dimension to the Fisherian sexual selection process.
Cryptosporidium and Giardia as water contaminant pathogens in Hungary
Authors: Plutzer Judit
Published: November 2013

Introduction: Many species of Cryptosporidium, and two assemlages of Giardia duodenalis cause typically acute diaorrhoea in human. The oocysts and cysts of these parasites excreted in faeces are capable of infecting other hosts and those are environmentally stable. Aim: The aims of the study were to evaluate the prevalence and genotypes of Cryptosporidium and Giardia species from different water sources as well as to monitor and characterize the (oo)cyst contamination sources in watersheds. In addition, an epidemiological study was performed in three selected settlements. Method: Wide range of modern epidemiological and molecular detection methods have been applied. Results: (Oo)cysts densities were associated with water receiving effluents of sewage treatment plants or originating from a forest environment. It was confirmed, that cattle can be a source of Cryptosporidium oocysts at watersheds and aquatic birds can play a role in the environmental dissemination of these protozoa. The epidemiological study demonstrated a specific epidemiological situation, giving essential evidence about giardiasis in asymptomatic carriers. The applied novel detection technology was found to be cost effective and simple procedure for screening catchments to identify those that require further treatment and more detailed microscopic counts. Conclusions: The presented results contribute to a better understanding the epidemiology and relevance of waterborne parasites, their surveillance and performance of future control measures to prevent waterborne infections in Hungary. Orv. Hetil., 154(46), 1836–1842.
Vitamin D level in Hungarian patients with inflammatory bowel diseases
Authors: Lőrinczy Katalin , Lakatos Péter László , Tóth Miklós , Salamon Ágnes , Nemes Adrienn , Csontos Ágnes Anna , Fekete Bálint , Terjék Orsolya , Herszényi László , Juhász Márk , Tulassay Zsolt , Miheller Pál
Published: November 2013

Introduction: Vitamin D has an important role in the immune regulation. Vitamin D is essential for innate and adaptive immune systems and it plays a significant role in the formation of immune tolerance, as well. Aim: Vitamin D deficiency has been observed in patients with inflammatory bowel diseases in Western Europe, but there is no data available from Eastern Europe. Method: The study included 169 patients with inflammatory bowel disease. Results: The median vitamin D level was 22.7±10.6 ng/ml. Only 20% of the patients had adequate vitamin D level (>30 ng/ml), 52% had vitamin D insufficiency (15–30 ng/ml), and 28% of them had severe vitamin D deficiency (<15 ng/ml). Vitamin D concentration failed to correlate with clinical activity indexes (partial Mayo score: r = –0.143; Crohn’s disease activity index: r = –0.253) and with inflammatory parameters (C-reactive protein: r = 0.008; erythrocyte sedimentation rate: r = 0.012). Conclusions: Since vitamin D deficiency can be frequently observed in Hungarian patients with inflammatory bowel disease, its level should be tested in these patients. Orv. Hetil., 154(46), 1821–1828.
Ultra-high Molecular Weight Polyethylene /Graphite Nanocomposites Prepared by High-energy Cryomilling.
Authors: Vazquez-Rodriguez Sofía , Rodríguez-Vázquez Gloria E. , Sepulveda-Guzman Selene , Reyes-Melo Martín E. , Morelos-Gomez Aaron , Cruz-Silva Rodolfo , Terrones Mauricio
Published: November 2013

Ultra-high molecular weight polyethylene/graphite nanocomposites were prepared by high-energy cryogenic milling followed by syntering. Microstructure changes shows that graphite was reduced to graphite nanoplatelets by high-energy cryomilling and partial exfoliation of graphite to few layered graphene nanoplatelets occurred in a small extent. The resulting nanocomposites revealed high electrical conductivity and good mechanical performance. Thermal characterization of the nanocomposites was also carried out by differential scanning calorimetry.
Antídotos e medicamentos utilizados para tratar intoxicações no Brasil: necessidades, disponibilidade e oportunidades
Authors: Galvão Tais F. , Bucaretchi Fabio , De Capitani Eduardo M. , Pereira Maurício G. , Silva Marcus T.
Published: November 2013

Antídotos e determinados medicamentos são essenciais ao tratamento de algumas intoxicações e não podem sofrer falhas no abastecimento, sob o risco de prejudicar a saúde e a segurança da população. O objetivo deste trabalho foi avaliar a disponibilidade de antídotos e medicamentos recomendados para o tratamento de intoxicações no Brasil. A partir de consensos internacionais, foram selecionados 41 antídotos para análise, todos sem patente em vigência. Desses, 27 são registrados, porém 11 estão disponíveis em formas inadequadas ao tratamento de intoxicações, restando 16 medicamentos comercialmente disponíveis. Somente um terço dos medicamentos necessários para o tratamento de intoxicações está incluído na relação de medicamentos essenciais do país. Em adição, é apresentada proposta de suprimento das demandas a um dos antídotos, anticorpo antidigoxina, considerando a capacidade de produção nacional de imunobiológicos. Os resultados demonstram limitação da assistência adequada aos pacientes intoxicados no país e reforçam a necessidade urgente de políticas públicas na área.
What matters most?: evidence-based findings of health dimensions affecting the societal preferences for EQ-5D health states
Authors: Andrade Monica Viegas , Noronha Kenya Valeria Micaela de Souza , Maia Ana Carolina , Kind Paul
Published: November 2013

This study analyzes how different health dimensions defined by the EQ-5D-3L instrument affect average individual preferences for health states. This analysis is an important benchmark for the incorporation of health technologies as it takes into consideration Brazilian population preferences in health resource allocation decisions. The EQ-5D instrument defines health in terms of five dimensions (mobility, daily activities, self-care activities, pain/discomfort, and anxiety/depression) each divided into three levels of severity. Data came from a valuation study with 3,362 literate individuals aged between 18 and 64 living in urban areas of Minas Gerais State, Brazil. The main results reveal that health utility decreases as the level of severity increases. With regard to health issues, mobility stands out as the most important EQ-5D dimension. Independently of severity levels of the other EQ-5D-3L dimensions, the highest decrements in utilities are associated with severe mobility problems.
Evidence-based process for decision-making in the analysis of legal demands for medicines in Brazil
Authors: Figueiredo Tatiana Aragão , Osorio-de-Castro Claudia Garcia Serpa , Pepe Vera Lúcia Edais
Published: November 2013

Legal actions have been playing a significant role as an alternative pathway to access to medicines in Brazil. These lawsuits demand medicines used in Primary Health Care as well as medicines that are still in clinical research and have not been market approved by the Brazilian National Agency for Sanitary Surveillance (ANVISA). The goal was to analyze medicines demanded through lawsuits brought to the judicial district which includes the city of Rio de Janeiro, Brazil, from July/2007 to June/2008. The medicines in 281 lawsuits were examined for their respective indications, classified according to their presence in publicly-funded lists, market approval by ANVISA, compliance with national clinical guidelines, existence of alternative therapies in lists and support of indication by scientific evidence. Six different categories were described, which are deemed useful to managers and the Judiciary in decision-making. The support of evidence is of utmost importance for medicines that are not included in public funding lists and also for those with no available therapeutic alternatives.
Are Targeted Therapies a Consideration in Poorly Differentiated Neuroendocrine Tumors?
Authors: Sorscher Steven
Published: November 2013

The close relationship between poorly differentiated NETs (PDNETs) and well or intermediately differentiated neuroendocrine tumors (NETs) is evidenced by the World Health Organization criteria for distinguishing these groups and by recognition by the National Comprehensive Cancer Network that octreotide therapy should be considered in some PDNETs. Based on the possible derivation from similar normal cells and the somewhat arbitrary World Health Organization distinction, particularly between intermediate and poorly differentiated NETs, it seems reasonable that future studies of targeted agents in the treatment of NETs should evaluate patients with PDNETs as well.
Standardized Approach to Lymphedema Screening
Authors: Dylke Elizabeth S. , Ward Leigh C. , Kilbreath Sharon L.
Published: November 2013

This letter concerns the recent article by O'Toole et al. on the need to standardize the screening and diagnosis of lymphedema. Perometry and bioimpedance spectroscopy, the potential of combining new technologies and available clinical tools, and the need for evidence are discussed.
Directed seed dispersal of Piper by Carollia perspicillata and its effect on understory plant diversity and folivory
Authors: Salazar Diego , Kelm Detlev H. , Marquis Robert J.
Published: November 2013

Directed dispersal occurs when seeds are differentially deposited to sites where offspring survivorship is higher than at randomly chosen sites. Traditionally, characteristics of the dispersal target sites that could increase survivorship of the dispersed plants are thought to be intrinsic to the sites. If directed dispersal is constant over extended periods of time, however, it is likely that nonrandom patterns of dispersal could modify the ecological characteristics of the target site in ways that could increase survivorship and fitness of the dispersed plants. Here we report patterns of Piper diversity (richness, equitability, and similarity) and Piper folivory within plots near natural or artificial roosts of Carollia perspicillata vs. similar plots without bat roosts. Plots with bat roosts, both natural and artificial, had significantly higher Piper species diversity. Additionally, we found that plots with a higher Piper species diversity showed less specialist folivory, higher generalist folivory, and lower total herbivore leaf damage than plots with low Piper diversity. Finally, plots with bat roosts also showed less specialist folivory, lower generalist folivory, and lower total folivory when compared to plots without roosts. We propose that long‐lasting nonrandom patterns of seed dispersal can change the local ecological characteristics of target sites via changes in plant diversity, and that these changes are likely to reduce the local rates of folivory and, therefore, increase seed and adult plant survivorship
A multi‐decade time series of kelp forest community structure at San Nicolas Island, California (USA)
Authors: Kenner Michael C. , Estes James A. , Tinker M. Tim , Bodkin James L. , Cowen Robert K. , Harrold Christopher , Hatfield Brian B. , Novak Mark , Rassweiler Andrew , Reed Daniel C.
Published: November 2013

San Nicolas Island is surrounded by broad areas of shallow subtidal habitat, characterized by dynamic kelp forest communities that undergo dramatic and abrupt shifts in community composition. Although these reefs are fished, the physical isolation of the island means that they receive less impact from human activities than most reefs in Southern California, making San Nicolas an ideal place to evaluate alternative theories about the dynamics of these communities. Here we present monitoring data from seven sampling stations surrounding the island, including data on fish, invertebrate, and algal abundance. These data are unusual among subtidal monitoring data sets in that they combine relatively frequent sampling (twice per year) with an exceptionally long time series (since 1980). Other outstanding qualities of the data set are the high taxonomic resolution captured and the monitoring of permanent quadrats and swaths where the history of the community structure at specific locations has been recorded through time. Finally, the data span a period that includes two of the strongest ENSO events on record, a major shift in the Pacific decadal oscillation, and the reintroduction of sea otters to the island in 1987 after at least 150 years of absence. These events provide opportunities to evaluate the effects of bottom‐up forcing, top‐down control, and physical disturbance on shallow rocky reef communities.
Canopy volume–aboveground biomass relationships of desert perennials and the effects of elevated CO2
Authors: Vanier Cheryl H. , Newingham Beth A. , Smith Stanley D.
Published: November 2013

Known allometric relationships between aboveground plant biomass and canopy volume allow standing biomass and net primary productivity (NPP) to be estimated non‐destructively. Canopy volume–aboveground biomass relationships are published for many ecosystems, but not for most desert species. It is also unknown if elevated atmospheric carbon dioxide [CO2] affects canopy volume–aboveground biomass relationships in desert perennials, limiting efforts to model NPP in an elevated CO2 environment. We measured canopy volume and aboveground biomass for perennial plants in the Mojave Desert, USA, at the Nevada Desert FACE Facility (NDFF): four species before treatment and 22 species after 10 years (1997–2007) of elevated CO2. Canopy volume to aboveground biomass allometry was estimated for each of the nine most common species individually; the remaining 13 species and unidentified dead shrubs combined to form a single “other” group. The resulting slopes and intercepts, which were estimated using a robust version of major axis regression, were compared across treatments and time points. None of the species had altered allometry in elevated CO2 compared to ambient CO2 treatments, nor did the relationships change over time. Data for each species were therefore combined across treatments and time points to provide the best available predictive equations relating canopy volume and aboveground biomass. The data set contains the canopy volume and aboveground biomass for all 3702 individual plants that were measured. We provide the regression coefficients relating canopy volume to aboveground biomass for both treatment and time comparisons and a single equation that predicts aboveground biomass from canopy volume for each species group. Our results suggest that grasses, forbs, and cacti may increase more rapidly in canopy volume than aboveground biomass, resulting in more shallow slopes compared to woody shrubs. The most notable limitation of this data set is that the maximum plant size at this site may be smaller than at other locations with the same species. The canopy volume to aboveground biomass equations could be improved by adding data from additional locations. Our results suggest that aboveground biomass for desert perennial plants in elevated CO2 conditions may be reasonably estimated from the allometry of plants under ambient CO2.
Antarctic Site Inventory breeding bird survey data, 1994–2013
Authors: Lynch Heather J. , Naveen Ron , Casanovas Paula
Published: November 2013

This data set represents the accumulation of 19 years of seabird population abundance data collected by the Antarctic Site Inventory, an opportunistic vessel‐based monitoring program surveying the Antarctic Peninsula and associated sub‐Antarctic Islands. This Data Paper, which includes 1124 records from 113 locations for seven species of seabirds (Adélie Penguin [Pygoscelis adeliae], Gentoo Penguin [P. papua], Chinstrap Penguin [P. antarctica], Macaroni Penguin [Eudyptes chrysolophus], Blue‐eyed Shag [Phalacrocorax atriceps], Kelp Gull [Larus dominicanus], and Southern Giant Petrel [Macronectes giganteus]), includes data already published by the Antarctic Site Inventory as well as seven years of recent data not previously published. Census data represent a mix of nest and chick counts; each census record includes the location, date, and precision of the census count, along with any auxiliary notes. Included with the database are maps to clarify the location of specific breeding populations that may be new (and thus not previously reported) or ambiguous. This compilation represents the best single source of raw data on the spatiotemporal dynamics of the Pygoscelis penguins in the Antarctic Peninsula region and provides population data on several flying bird species less frequently studied.
Do septic tank systems pose a hidden threat to water quality?
Authors: Withers Paul JA , Jordan Philip , May Linda , Jarvie Helen P , Deal Nancy E
Published: November 2013

Aquatic ecosystems are being degraded by anthropogenic pollution on a global scale. Septic tank systems (STS), which are widely distributed in rural and peri‐urban areas, are one potential source of water pollution. Although generally regarded as the most efficient method for onsite treatment of domestic wastewater, we question whether current regulation and management of these systems is sufficient to guarantee that they function effectively. Here, we present watershed‐specific examples that illustrate some of the problems that arise when many years of inadequate regulation and management result in a legacy of failing STS that can become long‐term, chronic sources of nutrient pollution. Our data suggest that more accurate accounting of the location, performance, and degree of failure of STS, and more research into their impacts on water quality, would improve source attribution of pollutants within rural watersheds. This would ensure that education of homeowners, mitigation, interdisciplinary research, and technological innovation could be targeted in a cost‐effective way.
Portable Technology Puts Real-time Automated Mineralogy on the Well Site
Authors: Ashton Tom , Ly Chi Vinh , Spence Graham , Oliver Guy
Published: November 2013

With the growing interest in the using hydraulically fracturing reservoirs both in main land USA and now globally, there has been a growing need to better characterize the reservoir to maximize hydrocarbon recovery while also reducing the overall cost in the recovery of the hydrocarbon. With current fracc-ing regimes relying on a large number of stages to ensure maximum recovery, which in many cases leads to upwards of 30% of these stages being unproductive. This reduces the overall profitability of well even with maximum hydrocarbon recovery. With the ongoing development of automated mineralogy tools, such as the RoqSCAN, there is now the ability to characterize a reservoir at the well-site in real-time and also rapidly in a laboratory.

In this paper we will review the current development of these mobile and ruggedized instruments using a real life project for Eagleridge Energy LLC, on their Burgess lateral well. The paper will show the application of automated mineralogical analysis of cuttings samples pre-drilling in defining stratigratic zones via mineralogy/elemental data. And then explore the application of the same data to assist, and in this case lead, the decision making process during directional drilling of the lateral well. The paper will also look at the use of the technology in defining tactical fracc-ing zone based on rock properties (e.g. ductility) determined from the mineralogical, elemental and textural data.

This paper will show that through the use of automated mineralogical instruments, such as the RoqSCAN, companies can pro-actively steer wells by identifying mineral changes within lateral borehole, indicating a deviation from the target zone. Additionally, this type of technology can be used to reactively steer by it ability to rapidly identification subsurface changes, such as unknown (undetected) faults. Finally the paper will show that through through the better characterization of this reservoir companies can reduce the risk accociated with the drilling of expensive lateral wells.
Multi-Stage Large Scale Hydraulic Fracturing in Horizontal Well, a First in India
Authors: Stolyarov Sergey , Sookprasong Andy , Sargon Mark
Published: November 2013

The first of its kind horizontal ‘proof of concept’ well, in India, Cambay-76 was drilled into the Late Eocene tight hydrocarbon reservoir of the Cambay Basin and completed with an Open Hole Multi-Stage (OHMS) swell packer completion. Drilling and completion operations were followed by another first of its kind in India, multi-stage hydraulic fracturing treatment of the Eocene EP-III/EP-IV zone. The hydraulic fracture jobs pumped the largest treatment fluid volumes in a well in India as well as placed the largest quantity of proppant in a single well in India. The application of horizontal well technology and multiple-stage hydraulic fracturing techniques has permitted the evaluation of "tight" hydrocarbons. The OHMS is comprised of eight (8) water-activated swell packer stages with two (2) ball actuated fracture ports per stage, totalling 16 fracture initiation points. Tests conducted on selected core samples from an offset well provided basic rock properties and rock mechanical properties that were used in the fracture design and planning. After closure analysis (ACA), following a minifrac, provided reservoir properties to aid in production forecast. Microseismic monitoring was employed during all fracture treatment phases and provided data to determine the fracture geometry. Information obtained from the microseismic was used in hydraulic fracture simulator software to generate a Discrete Fracture Network (DFN) model to allow visualization of the generated discrete fracture network.

This paper describes the lessons leant in the development of a tight hydrocarbon reservoir and demonstrates that the "proof of concept" can be scaled up across unconventional reservoirs in India. Extensive laboratory studies using formation cores and Microseismic monitoring results are also presented.
Physical and Numerical Simulation of Hydraulic Fracture Initiation and Propagation in Gas Shale
Authors: Li Yongping , Wang Yonghui , Ding Yunhong , Wang Xin , Yang Lifeng
Published: November 2013

Every year tens of thousands of shale gas wells were stimulated in the world. The initiation and propagation mechanism of hydraulic fracture in gas shale is not very clear unlike in the sandstone and carbonate. To investigate this problem, some large scale shale outcrop samples were tested with a true tri-axial rock mechanics frame, where the in-situ stress can be modeled. The size of sample is 30cm*30cm*30cm, and a borehole was drilled in it. Then the hydraulic fracturing was modeled by injecting fluid in the borehole with precise pump. The pumping rate and the treatment pressure can be recorded with acquisition system. The experiment results show the hydraulic fracture geometry is very complex and like network in shale because of the existence of beddings. And the fracture is significantly controlled by the beddings even though the difference of horizontal stress reaches 7MPa.

To further investigate the effect of different factors on the hydraulic fracture propagation in large scale shale, a new numerical simulation method was developed based on the FEM. In this method, a special failure process mode was adopted, which makes the method be able to model the fracture propagation behavior. The validity of numerical method was proved with comparison of physical and numerical result. The numerical simulation results show the stress status and existence of beddings are the keys to form complex network for shale. And the complex fracture geometry in shale was gotten under different condition.

The physical and numerical results can help guide the selection of well/layer and the optimization of hydraulic fracturing design.
Measurement of Relative Permeability of Coal to Gas and Water
Authors: Ham Y.. , Kantzas A..
Published: November 2013

Relative permeability of coal to gas and water is an important variable in coalbed methane reservoir development as it is required for reserve estimation and field production planning. In this study, gas-water relative permeability of two coal samples: Grande Prairie (GP) and Goldsource (GS) were determined by the Johnson-Bossler-Naumann (JBN) method, which is widely used for petroleum reservoir rocks.

An experimental apparatus was designed, built, tested, and commissioned for various two-phase gas-water relative permeability measurements. The gas phases used were helium, methane, and carbon dioxide in this order of adsorbing strength on coal and the water phase used was formation brine. Forty-eight drainage and imbibition displacement runs were carried out on the two coal samples using helium-brine, methane-brine, and carbon dioxide-brine combinations at three different operating pressures (100, 300, 400 psi) at a constant overburden pressure (800 psi), and the results were analyzed and plotted on drainage and imbibition curves.

Imbibition relative permeability showed that the irreducible water saturation correlated with pressure and the absolute permeability of the coal samples changed after each experiment. The GS coal sample showed a greater two-phase flow saturation range than the Grande Prairie coal sample. In both cases, the relative permeability to gas was low and high for water. The coal samples tended to become more water-wet at higher pressures in the case of adsorbing gases, namely methane and carbon dioxide but in the case of non-adsorbing gas helium, higher pressure prevented the inflow of water into the smaller pores leading to a decrease in irreducible water saturation with an increase in pressure. The drainage experiments were highly unstable based on the Instability Number calculated. The resulting relative permeability curves showed oscillation.

From this study, it was concluded that coal relative permeability to gas and water depended on the nature of gas, the operational pressure, and fluid-mineral interactions.
Dynamic Positron Emission Tomography: Application to Imaging Fluid Mobility in Fractured Cores
Authors: Maucec Marko , Dusterhoft Ron , Rickman Richard , Gibson Ron , Buffler Andy , Stankiewicz Maciek , van Heerden Michael
Published: November 2013

Positron emission tomography (PET) continues to have wide-ranging medical application and is based on the detection of gamma radiation emitted from the decay of certain types of radionuclides. Modern PET scanners produce 3D images of the radiation source, in discrete time steps, using tomography analysis. This paper presents an application of PET for studying fluid mobility in pressurized low-permeability rocks in the presence of natural fractures. This technique uses a high-resolution PET scanner and image reconstruction based on filtered back-projection. Traditional techniques have been limited to pressure measurement of fracture conductivity and effective permeability, but little is understood about the dynamic flow and velocity profiles within the fracture.

The objective of this work was to determine if it is possible to measure the dynamic (e.g., time-lapse and continuous) distribution of fluid flow as a function of the overburden stress. PET imaging was applied to the flow of brine solution, which was tagged with 18F-fluorodeoxyglucose (FDG) positron emitting radionuclide, through nonfractured sandstone and naturally fractured shale cores. A special composite container was manufactured to sustain high-pressure conditions and minimize the absorption of emitted gamma rays. The experimental apparatus is described, and it is demonstrated that 3D images obtained with a grid resolution of 2 × 2 × 2 mm3 allow clear determination of the fluid flow rate through the core as a function of overburden pressure and time. PET images are direct observations of the radiation source and allow an unambiguous determination of the fluid distribution in the core. The results of this research can be used to validate the numerical modeling of fluid flow through fractured rock matrices, to enable more accurate estimates on the directionality of fractures from the fluid distribution as a function of time, and to obtain more quantitatively sound estimates of fracture connectivity.
Moving CBM Reservoirs into Production – Developing a New Workflow
Authors: Sidiq Hiwa , Khalili Ahmad Dehghan
Published: November 2013

There have recently been extensive attempts to better model and simulate coal bed methane (CBM) reservoirs - something which is particularly pertinent to Australia which has an estimated 198 billion cubic meters (Bcm) of CBM resources and Queensland where AUS$50 billion worth of CBM projects are currently in progress.

Yet, while most reservoir simulators are equipped to simulate fluid flow in CBM reservoirs, there is a need for a workflow that is better able to locate the sweet spots in CBM. To this end, this paper will examine recent technical developments in reservoir modelling and how modelling tools can be better utilised to optimise production in CBM reservoirs through simulation.

The paper will look at the challenges in collecting the right amount of data to compile an accurate characterisation of a preexisting fracture network (cleats) and its structural complexities. The current low gas prices sometimes prevent the acquisition of such data – data that is an essential input to drilling strategies, fracture programme design and well spacing.

The paper will also examine how the transport along a wellbore is not only controlled by the fractures around the well but also by the drained volume. In such cases, the pre-existing fractures and their reactivation during the fracturing stage are not always sufficient to determine the amount of gas that can be recovered during production.

With this in mind, the paper will also look at the challenge of generating a good estimation of the size of the gas-in-place within CBM reservoirs and the role of reservoir modelling and simulation within this area.
A Holistic Approach to the Appraisal Stage of Shale Gas Resources
Authors: Navarette Mike , Chorn Larry , Maucec Marko
Published: November 2013

Source rock reservoirs (SRRs) are found in conventional oil and gas basins. The exploration for and the evaluation of an SRR depends on the geology, geochemistry, petrophysical, and geomechanical parameters; as well as economic constraints in the targeted area. The SRR exploration methodology is fundamentally different from conventional exploration as SRR objectives require a program that includes a data-acquisition focused effort in the early stages of exploration and appraisal. We highlight a holistic approach to shale gas development that has been developed in detail, encompassing more than 25 years of Halliburton experience in U.S. shale plays. Unconventional SRRs impose significant engineering constraints because reserves are spread out across large compartmentalized, stacked or layered reservoirs, which are highly heterogeneous (faulted and fractured) and confine wide ranges of mineralogy. The objective of our work is to provide a better understanding of the SRRs' reservoir quality and deliverability to assist with maximizing well productivity, improving hydraulic fracturing stimulation, and optimizing drilling and completion efficiency. This paper identifies critical paths and key technical elements or tasks associated with SRR basin screening, appraisal, and field development. Previous data acquired (seismic, logs, cuttings, mud logs, and well files) and commercially successful analogs are used to evaluate and benchmark potential hydrocarbon reserves. A methodical approach that addresses the following key tasks is presented: Determine critical SRR attributes.Map selected attributes in the SRR model.Establish best reservoir targets (sweet spots) with well location and orientation.Maximize the stimulation potential and recovery factor.

Our work provides a proven road map for the evaluation and development of SRRs. Critical paths with the associated key technical elements address and provide a project scope of challenges, which enables a holistic solution to successful unconventional SRR development.
Novel Chemical Stimulation Techniques to Enhance Coal Permeability for Coal Seam Gas Extraction
Authors: Turner Luc G. , Steel Karen M. , Pell Stephen D.
Published: November 2013

Permeability is a key controlling factor for gas migration in coal seam reservoirs and has invariably been the barrier to economically viable gas production. A large variety of completion techniques have been utilised in coal bed methane (CBM) production with varying degrees of success. Low permeability stimulation treatments primarily consist of hydraulic fracturing and multi-lateral horizontal wells. High stress, cleating and low Young's Modulus in coal can lead to complex and inefficient fractures compared to conventional reservoirs. The creation and transport of fines due to shear failure can reduce the fracture conductivity and thus coal permeability. The unique structure of coal may offer opportunities for the development of new methods for creating gas flow paths for low permeability coals.

Coal seams contain upwards of approximately 10 wt.% mineral matter with a significant proportion contained within the natural cleat system. This study has involved characterization of the cleat system in a core sample from the central Bowen Basin. It was found that the volume of cleats was around 0.52% with around 73% of the cleats mineralized. LTA-XRD analysis found the minerals in the whole coal to be quartz, kaolinite, clays, calcite, apatite and bassanite. SEM-EDS analysis found that calcite and kaolinite dominate the mineralology of the cleats. The removal of these minerals is thought to create additional gas flow paths whilst maintaining the structural integrity of the coal. Furthermore, given that coal is reactive toward oxidants there is the possibility to undergo controlled reaction of the macromolecular coal structure to further enhance permeability.

Batch leaching experiments with HCl were effective at dissolving the Ca-bearing minerals. Of the oxidants studied, potassium permanganate appeared to break down the coals structure, producing a significant level of organics in solution Both hydrogen peroxide and Fenton's reagent didn't yield organics in solution although a slight mass loss was found, indicating that oxidation may have occurred with CO2 produced as the reaction product. Permeability tests were performed on a Bowen Basin core sample with HCl solutions. An increase of 7 wt% was observed, however, permeability was found to decrease again on account of the confining pressure exceeding the cleat pressure.
Lessons Learned from Engineering Analysis of Fracture Injection Tests from Different CBM Reservoirs
Authors: Pankaj P.. , Sinha M.. , Barasia A.. , Venkateshwaran R.. , Shado O.. , Nawaz Sami , Ghosh Baijayanta , Kumar Vikash
Published: November 2013

With the growing energy demand, operators are looking at exploiting every source of energy and have intensified exploration in coalbed methane (CBM) reservoirs. In the area under consideration, hundreds of wells have been drilled to a few thousands of feet depth covering multiple coal seams. Most of these coal seam reservoirs are CBM reservoirs that need massive dewatering to economically produce the methane gas adsorbed on the coal surface. Hydraulic fracturing has become an important tool that not only enables accelerated dewatering to reduce reservoir pressure to the critical desorption pressure, but also creates a conductive path for gas production and minimizes non-Darcy effects.

However, the art of hydraulic fracturing in these unconventional reservoirs is not easy to master. Complex formation behaviors such as poroelasticity, nonideal pressure leakoff, state of formation damage, orientation of cleat system, high fracture gradients, etc. constantly challenge the fracturing design and execution in these unconventional reservoirs. Neglecting pressure responses and having a poor understanding of formation characteristics can compromise the placement of optimized hydraulic fractures, and, ultimately, production results.

Hydraulic fracture engineering analysis was performed on all the CBM wells in two exploratory fields and one development field of a CBM basin have been consolidated; the analysis included approximately 40 fracture treatments from these three different fields. Fracture pressure diagnostics such as G-function plots, leakoff mechanisms, and closure pressure analysis, were part of the design, execution, and evaluation cycle to establish and characterize the hydraulic fractures (HF) in the different coal seams. Post-fracture studies completed the design execution and evaluation cycle.
Innovation, Motivation, and Fear: A Novel Perspective for Unconventional Oil
Authors: Bunio Gary L. , Gates Ian D.
Published: November 2013

The focus of this paper is innovation in oil sands recovery technology. Canada hosts the third largest reserves of petroleum in the world, mostly in heavy oil/oil sands reservoirs. The two commercial in situ recovery technologies, Cyclic Steam Stimulation and Steam-Assisted Gravity Drainage, were both invented >30 years ago; both use large amounts of water and emit carbon dioxide. Industry is facing a critical point where it is imperative to find new technologies. It has been a significant challenge to find new processes with large reductions of water and carbon dioxide emissions. Another critical issue is adoption time scale – in the past, new technologies have taken 10–20 years to become commercial – this pace must be accelerated. The oil sands industry needs to improve the innovation cycle of oil sands extraction technologies. The objective here is to understand how to do this, to describe factors that encourage and discourage innovation, and to recommend strategies to enable and stimulate non-incremental innovation. It is interesting to note that despite only a few oil companies still having research laboratories and permanent research staff, abundant potentially inventive scientific, engineering, and management staff exist in oil companies. So the question becomes: what is preventing them from developing a plethora of inventions and bringing creativity to issues confronted by the oil sands industry? It does not appear to be only a technical issue but also a social one. Market, resource, and social issues lead to this result: most petroleum funding directed at near market iterations, short term incentives (increasing shareholder value), government funding matched to current industry activity and thus linked to market forces, low funding levels, culture of risk adversity and fear of risk, innovation curbed by regulatory factors or internal work overload, and high costs due to investment, variable resource quality, high capital costs, and oil price volatility.
Monitoring Well Integrity and Groundwater Protection with Innovative Logging Practices in Unconventional Horizontal Wells
Authors: Foianini I.. , Nurhayati T..
Published: November 2013

Hydraulic fracturing and horizontal drilling have catalyzed the recent United States (US) hydrocarbon production "renaissance," spearheaded by unconventional asset development. The increase in oilfield activity, however, has exposed groundwater contamination as a potential environmental concern associated with the use of these two technologies. Government and state agencies have revisited regulations to help ensure well integrity, but operational success is currently limited because of tool deployment and centralization issues in horizontal wellbores.

The combination of acoustic logging and conveyance technologies with field engineering insight has created a unique solution to well integrity monitoring in horizontal well intervals. Various successful logging services have been performed in wells producing from the Marcellus shale play in Pennsylvania.

A well operator needed to determine proper cement placement between different fracturing stages to avoid unwanted fluid movement throughout the wellbore annulus. The logging tool string, composed of ultrasonic scanning and cement bond log (CBL) tools, was transported through the horizontal wellbore using a tractoring device.

Tool centralization, which is critical to accurate operation of acoustic tools, is difficult to achieve in horizontal wellbores because of the influence of gravity and friction forces. This challenge was overcome by integrating centralization equipment for additional tool support while maintaining wireline tension limits.

This case study discusses the operational background and challenge, creation of this innovative tool setup, and the effects this service will have on performing successful well integrity monitoring in additional unconventional horizontal wells.
Vitrinite Reflectance Versus Pyrolysis Tmax Data: Assessing Thermal Maturity in Shale Plays with Special Reference to the Duvernay Shale Play of the Western Canadian Sedimentary Basin, Alberta, Canada
Authors: Wust Raphael A. , Hackley Paul C. , Nassichuk Brent R. , Willment Nicole , Brezovski Ron
Published: November 2013

In unconventional, self-sourced sedimentary rocks, organic matter type and maturity and therefore the hydrocarbon production potential, are the most critical parameters when evaluating unconventional hydrocarbon resources. Several methods exist that determine the maturity level of sedimentary rocks and the organic matter. Organic maturity is commonly determined by vitrinite reflectance (%Ro). Vitrinite is a type of maceral that is derived from higher order plants. In rock with little or no vitrinite, bitumen or other organic matter type reflectances are measured and calculated to a normalized reflectance value (%Ro). Measuring vitrinite/bitumen reflectance is time-consuming and subject to the interpretation of the analysts. Alternatively, organic matter type and maturity are also measured using Rock Eval or equivalent pyrolysis techniques. The temperature (Tmax) at which thermal cracking of heavy hydrocarbons and kerogen reaches the maximum depends on the nature and maturity of the kerogen and indicates the level of thermal maturity. Pyrolysis results are independent of an operator although the data output may still require validation. In order to compare data from these two techniques, a study from the Barnett in 2001 produced a conversion formula to calculate %Ro from Tmax data. The conversion formula (calculated Ro = 0.0180 × Tmax − 7.16) has been used extensively in basins worldwide despite the fact that the correlation was produced for the Barnett shale. Here we present new maturity data (>100) (%Ro and Tmax) within the Duvernay Formation in Alberta, Canada, which is compared to data using the conversion formula. The Duvernay Formation of the Western Canada Sedimentary Basin is an Upper Devonian (~360 Ma) source rock which has been praised as one of the most promising oil/gas resource plays in Canada. Since late 2009, land sale activity has seen over $1.4 Bn spent in Alberta with land purchases focused in the Pembina and Kaybob areas. The total organic carbon (TOC) content of the Duvernay Formation can exceed 20 wt% in areas of low maturity but on average, the dark shales have TOC contents ranging between 4–11 wt%. TOC is a key indicator of hydrocarbon generation potential. In this study, we discuss the details of both analytical techniques, findings of the organic petrography, bitumen reflectance data and corresponding Tmax data. The data is also compared to calculated Ro values and problems using the formula are highlighted. In addition, the data is put into perspective of production information and the hydrogen-generative models (initial production data). The results show that inherent problems are manyfold and conversion calculations should be avoided in new formations where a conversion formula has not been established.
Surface Well Test of Methane Gas Saturation in CSG Lateral Completions During Dewatering Using Raman Spectroscopy
Authors: Mazumder S.. , Scott M.. , Pope J. M. , Morgan Q.. , Ramsay P..
Published: November 2013

This paper describes application of an established coal seam gas (CSG) testing technology to the reservoir and production conditions prevalent in the Bowen basin, Queensland, Australia. The technology involves using Raman spectroscopy to measure gas partial pressure in single phase fluids produced under pressure from dewatering coal seam gas wells. The technique's efficacy has been described extensively in technical literature. Prior tests have been conducted on permeable coals that produce several hundred BWPD. Applying the technology to tight coals in the Bowen basin is not considered straightforward.