bluuebunny/crossref_metadata_2025 huggingface dataset:
Data and Code for Analyzing Performance of QHY CMOS Cameras
Authors: Nandakumar Hari , Srivastava Shailesh
Published: October 2018

Expensive cameras meant for research applications are usually characterized by the manufacturers and detailed specifications [1] are available for them. Suppliers of inexpensive cameras usually do not provide such detailed information about their cameras. This data set provides the acquisition speed and noise characteristics acquired from a monochrome 1.2 megapixel CMOS camera, the QHY5L-II M [2]. The source code provided along with this data set [3] can also be used to acquire similar data for other QHY cameras. This enables the use of such cost-effective cameras for other scientific applications in other fields, beyond the designed use in Astronomy.
Catalytic/Protective Properties of Martian Minerals and Implications for Possible Origin of Life on Mars
Authors: Fornaro Teresa , Steele Andrew , Brucato John Robert
Published: October 2018

Minerals might have played critical roles for the origin and evolution of possible life forms on Mars. The study of the interactions between “building blocks of life” and minerals relevant to Mars mineralogy under conditions mimicking the harsh Martian environment may provide key insight into possible prebiotic processes. Therefore, this contribution aims at reviewing the most important investigations carried out so far about the catalytic/protective properties of Martian minerals toward molecular biosignatures under Martian-like conditions. Overall, it turns out that the fate of molecular biosignatures on Mars depends on a delicate balance between multiple preservation and degradation mechanisms often regulated by minerals, which may take place simultaneously. Such a complexity requires more efforts in simulating realistically the Martian environment in order to better inspect plausible prebiotic pathways and shed light on the nature of the organic compounds detected both in meteorites and on the surface of Mars through in situ analysis.
Surveying the Solar Power Gap: Assessing the Spatial Distribution of Emerging Photovoltaic Solar Adoption in the State of Georgia, U.S.A.
Authors: Tidwell Jacqueline Hettel , Tidwell Abraham , Nelson Steffan
Published: October 2018

Despite a global push in the development and implementation of widespread alternative energy use, significant disparities exist across given nation-states. These disparities reflect both technical and economic factors, as well as the social, political, and ecological gaps between how communities see energy development and national/global policy goals. Known as the “local-national gap,” many nations struggle with fostering meaningful conversations about the role of alternative energy technologies within communities. Mitigation of this problem first requires understanding the distribution of existing alternative energy technologies at the local level of policymaking. Using the State of Georgia, U.S.A. as a case study, we present a model for analyzing how existing adoption trends enable/limit conversation at the scale of local governance (i.e., county governments). Leveraging existing work on the Gini Coefficient as a metric for measuring energy inequity, we argue these tools can be applied to analyze where gaps exist in ongoing solar adoption trends. As we demonstrate, communities that adopt solar tend to be concentrated in a few counties, indicating existing conversations are limited to a circumscribed set of social networks. This information and the model we demonstrate can enable focused qualitative analyses of existing solar trends, not only amongst high-adoption areas but within communities where little to no adoption has occurred.
Transcriptome Analysis of Long Non-Coding RNA in the Bovine Mammary Gland Following Dietary Supplementation with Linseed and Safflower Oil
Authors: Ibeagha-Awemu Eveline M. , Li Ran , Dudemaine Pier-Luc , Do Duy N. , Bissonnette Nathalie
Published: October 2018

This study aimed to characterize the long non-coding RNA (lncRNA) expression in the bovine mammary gland and to infer their functions in dietary response to 5% linseed oil (LSO) or 5% safflower oil (SFO). Twelve cows (six per treatment) in mid lactation were fed a control diet for 28 days followed by a treatment period (control diet supplemented with 5% LSO or 5% SFO) of 28 days. Mammary gland biopsies were collected from each animal on day-14 (D-14, control period), D+7 (early treatment period) and D+28 (late treatment period) and were subjected to RNA-Sequencing and subsequent bioinformatics analyses. Functional enrichment of lncRNA was performed via potential cis regulated target genes located within 50 Kb flanking regions of lncRNAs and having expression correlation of >0.7 with mRNAs. A total of 4955 lncRNAs (325 known and 4630 novel) were identified which potentially cis targeted 59 and 494 genes in LSO and SFO treatments, respectively. Enrichments of cis target genes of lncRNAs indicated potential roles of lncRNAs in immune function, nucleic acid metabolism and cell membrane organization processes as well as involvement in Notch, cAMP and TGF-β signaling pathways. Thirty-two and 21 lncRNAs were differentially expressed (DE) in LSO and SFO treatments, respectively. Six genes (KCNF1, STARD13, BCL6, NXPE2, HHIPL2 and MMD) were identified as potential cis target genes of six DE lncRNAs. In conclusion, this study indicated potential roles for lncRNAs in mammary gland immune functions and development and provided potential candidate genes and pathways via which lncRNAs can function in diet responses.
Monitoring Effects of Drought on Nitrogen and Phosphorus in Temperate Oak Forests Using Machine Learning Techniques
Authors: Kotlarz Jan , Kubiak Katarzyna , Spiralski Marcin
Published: October 2018

Oak is a European tree species highly sensitive to drought. If declining symptoms appear they are often detectable at the crown (such as dieback) enabling monitoring using aerial images and remote sensing methods. Here, we analyzed the impact of short and long-term drought on oaks located in central Poland, between the years of 2014 and 2017. We used leaf nitrogen (N) and phosphorus (P) concentrations measured in the laboratory, aerial images collected in the range of 460-880 nm and machine learning techniques to estimate nutrient concentrations on the > 4000 oaks growing on gleysoil in the study area. We determined a negative impact on N and P concentrations during both types of drought stress (-23% and 19% for N concentration in leaves; -27% and -10% for P concentration in leaves) and an inconsiderable impact on N:P values (3% increase of N:P ration during short and 7% decrease of N:P ration during long-term drought stress). We found that the long-term drought impact was spatially diverse, possibly depending on the presence of drainage ditches and competing species.
ANN and DOE Analysis of Corrosion Resistance Inhibitor for Mild Steel Structures in Iraq
Authors: Sheet Eiman , Yamin Jehad , Al-Amiery Ahmad
Published: October 2018

Modelling of the effect of newly developed mild steel (MS) corrosion inhibitor in Iraq was investigated using artificial neural network (ANN) and Response Surface Methodology Design of Experiment (RSM-DOE) methods. The most significant parameters among the parameters studied and the optimum coating conditions was also investigated. Weight loss method (WLM) as well as Scanning electron microscope (SEM) were used in the experimental work to obtain data for modelling. The inhibitor used was made in the center’s laboratories called N-(3-Nitrobenzylidene)-2-aminobenzothiazole. The MS specimens were tested for different immersion times and corrosive solution temperatures. Different concentrations of the inhibitor from of 0, to 1000 mg/L were used in the study. The results showed that within the concentrations studied, the corrosion inhibition performance increased with increasing N-(3-Nitrobenzylidene)-2-aminobenzothiazole concentration. The ANN model proposed with the Gaussian activation function was accurate for both testing and validation up to 99%. The RSM method used indicated that comparing time and concentration alone, inhibitor concentration was more significant than the immersion time in the corrosive solution. On the other hand, the effect of temperature and time were opposite to one another. While increasing time of immersion increased corrosion rate, temperature effect was the opposite.
Sensory Analysis Test of Pounded Yam Made from a Pounding Machine Designed and Fabricated in Nigeria
Authors: Abulude F.O. , Elemide A.O , Oladipupo O.K , Ale T.A
Published: October 2018

Pounded yam eaten with any type of soup is a delicacy eaten by Nigerians.            It is manually prepared by pounding yam, cocoyam or combination with mortar and pestle. Preparation takes 30-45 mins. Researches on the improvements have taken place to reduce the heavy burden on the pounded yam preparation. One of the efforts made is the fabrication of pounding machine from the Department of Engineering, Federal College of Agriculture, Akure, Nigeria. The aim of this study is to carry out the organoleptic analysis of pounded yam produced from the fabricated machine. A ten-man panelist was used to determine the organoleptic analysis of the pounded yam in terms of the appearance, taste, colour, odour and texture. The panelists were scored with a class of quality grading: 22.6-25.0 (excellent), 20.2-22.5 (good), 18.2-20.1 (satisfactory), 16.2-18.1 (less satisfactory), and <15.2 (unsatisfactory). Also, sensory attributes were scored as 1= unsatisfactory, 2= less satisfactory, 3= satisfactory, 4=good, and 5= excellent. The results were statistically analysed. From the results it was found that the mean results of appearance, colour, odour, taste, and texture were 4.55, 4.43, 4.15, 4.32, and 4.08 respectively. Coefficients of variation (%) were 16.89, 17.80, 21.65, 15.67, and 24.40. The Skewness of the parameters was in negative, while only odour has its Kurtosis in negative form (-0.37). All the panelists rated the appearance (19-24%) of all the samples high above all other parameters. The Pearson Coefficient of Correlation and Principal Component Analysis showed elements of relationships between the parameters. In conclusion, the machine pounded yam was scored above satisfactory, which means the fabricated machine was efficient.
Finding Exact Forms on a Thermodynamic Manifold
Authors: Ju Chao , Stalzer Mark
Published: October 2018

Because only two variables are needed to characterize a simple thermodynamic system in equilibrium, any such system is constrained on a 2D manifold. Of particular interest are the exact 1-forms on the cotangent space of that manifold, since the integral of exact 1-forms is path-independent, a crucial property satisfied by state variables such as internal energy dE and entropy dS. Our prior work [1] shows that given an appropriate language of vector calculus, a machine can re-discover the Maxwell equations and the incompressible Navier-Stokes equations from data. In this paper, We enhance this language by including differential forms and show that machines can re-discover the equation for entropy dS given data. Since entropy appears in various fields of science in different guises, a potential extension of this work is to use the machinery developed in this paper to let machines discover the expressions for entropy from data in fields other than classical thermodynamics.
Analisis Kemampuan Penalaran Matematis Peserta Didik dalam Menyelesaikan Soal Cerita di SMAN 6 Malang
Authors: Linola Delima Mei , Marsitin Retno , Wulandari Tri Candra
Published: October 2018

Penelitian ini merupakan penelitian kualitatif dengan jenis penelitian deskriptif kualitatif yang bertujuan untuk mendeskripsikan kemampuan penalaran matematis peserta didik dalam menyelesaikan soal cerita di SMAN 6 Malang. Subjek dalam penelitian ini adalah peserta didik kelas XI MIPA 4. Indikator yang digunakan untuk menganalisis kemampuan penalaran peserta didik antara lain (1 ) melakukan manipulasi matematika, (2) menyusun bukti dan memberikan alasan terhadap kebenara solusi, (3) menyajikan pernyataan matematika secara tertulis, diagram, dan gambar, dan (4) menarik kesimpulan pernyataan secara logis. Teknik pengumpulan data terdiri dari tes tertulis dan wawancara. Analisis data yang digunakan dalam penelitian ini meliputi reduksi data, penyajian data, dan penarikan kesimpulan. Berdasarkan analisis data diperoleh hasil bahwa kemampuan penalaran matematis peserta didik kelas XI MIPA 4 SMAN 6 Malang dalam menyelesaikan soal cerita tergolong tinggi. Peserta didik dengan kemampuan penalaran kategori rendah sebanyak 4%, peserta didik dengan kemampuan penalaran kategori sedang sebanyak 32%, dan peserta didik dengan kemampuan penalaran kategori tinggi sebanyak 64%
Selected Physical Characteristics and Playing-Related Musculoskeletal Problems in Adolescent String Instrumentalists
Authors: Vinci Stefano , Smith Anne , Ranelli Sonia
Published: October 2018

PURPOSE: Music research has investigated the prevalence of playing-related musculoskeletal problems in adults and children, but the prevalence in adolescents has not been established. String instrumentalists report high problem rates, though it is unclear whether rates vary between
upper and lower strings in adolescent instrumentalists. Further, there is limited evidence for the association between physical characteristics and playing problems in this group of musicians. METHODS: Seventy-six adolescent string musicians from the West Australian Youth Orchestras were surveyed.
Their experience of playing problems, both symptoms (PRMS) and disorders (PRMD), within the last month and measurements of body mass index, hand span, and joint mobility (Beighton scale) were obtained. Prevalence rates were calculated and compared between upper and lower string instrumentalists
using a chi-squared test. Logistic regression examined the association of physical measures with playing problems, adjusting for confounding factors. RESULTS: Within the last month, 73.5% participants reported experiencing a PRMS and 26.5% reported experiencing a PRMD. There was no significant
difference between the problem rates in upper and lower string instrumentalists. After adjusting for potential confounders, an increasing count of hypermobile joints remained significantly associated with problems (OR 1.76, CI 1.02 to 3.04, p=0.042). CONCLUSIONS: This study found playing problems
are common in adolescent string instrumentalists, though rates did not differ between upper and lower string players. Joint hypermobility was associated with playing-related problems in adolescent musicians. Early identification of problems in this group of maturing musicians may help prevent
disabling disorders and maximize performance.
Virtual Reality Exposure Training for Musicians: Its Effect on Performance Anxiety and Quality
Authors: Bissonnette Josiane , Dubé Francis , Provencher Martin D , Moreno Sala Maria T
Published: October 2018

Music performance anxiety affects numerous musicians, with many of them reporting impairment of performance due to this problem. This exploratory study investigated the effects of virtual reality exposure training on students with music performance anxiety. Seventeen music students
were randomly assigned to a control group (n=8) or a virtual training group (n=9). Participants were asked to play a musical piece by memory in two separate recitals within a 3-week interval. Anxiety was then measured with the Personal Report of Confidence as a Performer Scale and the S-Anxiety
scale from the State-Trait Anxiety Inventory (STAI-Y). Between pre- and post-tests, the virtual training group took part in virtual reality exposure training consisting of six 1-hour long sessions of virtual exposure. The results indicate a significant decrease in performance anxiety for musicians
in the treatment group for those with a high level of state anxiety, for those with a high level of trait anxiety, for women, and for musicians with high immersive tendencies. Finally, between the pre- and post-tests, we observed a significant increase in performance quality for the experimental
group, but not for the control group.
Abstracts from the Literature, No. 68
Authors: Dawson William J
Published: October 2018

Installment #68
A Psychophysiological Case Study of Orchestra Conductors
Authors: Jaque S Victoria , Karamanukyan Isabel H , Thomson Paula
Published: October 2018

The psychological and physiological effects of performance were investigated in two professional orchestral conductors, with data collected prior to, during, and after a rehearsal and a public performance. The participants were given a battery of psychological self-report tests (anxiety,
dissociation, health inventory, fantasy proneness, shame, and flow). Ambulatory physiological monitoring (Vivometric LifeShirt® system) was conducted during both a rehearsal and public performance to gather information about the autonomic nervous system and heart rate variability (HRV).
One conductor had a history of asthma and anxiety, and the second conductor had coronary artery disease. The results revealed within-subject and between-subject differences in autonomic nervous system responses and HRV during several conditions (pre-performance rest, stair-climbing, rehearsal,
and performance). Based on heart rate, the physiological demands of professional conducting are reflective of work intensities considered “hard.” Both conductors experienced high flow states. Anxiety and coronary artery disease may have attenuated HRV resilience in this study.
It is recommended that noninvasive methods be implemented to assess cardiac autonomic activity in professional conductors, particularly during engagement in their professional activities. The findings suggest a need to further study anxiety, respiratory conditions, and cardiovascular risks
for conductors.
Self-Reported Injury and Management in a Liberal Arts College Dance Department
Authors: DiPasquale Sarah , Becker Nicole , Green Sarah , Sauers Kim
Published: October 2018

Dancers often view injuries as a necessary sacrifice for participating in their art form. The purpose of this research was to determine the frequency and patterns of injury in a non-conservatory, liberal arts dance environment. These data may enable dance departments to provide more
effective health resources. METHODS: Dancers registered in technique courses in a liberal arts dance department (including ballet, modern, tap, and jazz) completed an injury questionnaire immediately following the occurrence of any dance-related injury over the course of one semester. RESULTS:
Out of 168 students registered in the department, 46 injuries were reported throughout the semester. The greatest rate of injury was in September and December with 0.95 and 0.65 injuries reported per day, respectively. 89.1% of participants indicated that they would use a direct-access, on-campus
physical therapist or athletic trainer if available, though 45.7% of injured participants indicated that they would seek treatment off campus. CONCLUSIONS: Dancers in a liberal arts collegiate program may train at a higher intensity during the semester than summer break, which likely accounts
for the high incidence of injury in September. Of those injured, most planned on self-treating, but none planned on missing class. Pre-semester screening and post-semester cross-training education should be implemented in liberal arts dance programs to help decrease the rate of injury seen
when returning to dance following prolonged time off from dancing. Additionally, direct access to physical therapy or athletic training treatment would likely be utilized by these students if available.
The Bioethics of Music, the Music of Bioethics
Authors: Lubet Alex
Published: October 2018

Bioethics is rarely referenced in the scholarship of performing arts medicine (PAM). This essay argues that bioethical concerns loom far larger in the care of PAM patients than might typically be understood. This essay presents Beauchamp and Childress’s four principles of bioethics,
with examples pertinent to PAM, drawn from the author’s research and personal experience.
Hydraulic Fracture Height Growth: Pseudo-3D vs. Full 3D Modeling
Authors: de Pater C. J. , Shaoul J. R. , Northington N.. , Stelin I..
Published: October 2018

Advances in fracture mapping and full 3D modeling have yielded new insights into hydraulic fracture geometry, but it is still impossible to predict height growth. Fracture mapping data collected from a large number of treatments in different basins yield a rule-of-thumb for expected fracture height over fracture length (aspect ratio), but in specific cases fracture design optimization requires a more accurate forecast for height growth. Calibrated models with full 3D fracture geometry will give the best results, but in many projects the available data to calibrate such a model is severely limited. Knowing this, the question this paper attempts to answer is: "Will using a full 3D model give more reliable predictions of fracture geometry (maybe height growth) compared with pseudo-3D models?".

Using data from an instrumented field test and routine fracture treatments, the results of the different fracture models are tested. Even when detailed knowledge of stress and geomechanical properties are available, it is impossible to match observed fracture geometry using only conventional hydraulic fracture physics. So, even a full 3D model does not provide a true prediction of fracture geometry. Both pseudo3D and full 3D fracture models can match observed fracture geometry, but only by introducing additional parameters beyond conventional fracture propagation physics, such as formation lamination or fracture tip pore pressure.

A full 3D model with default input parameters and conventional fracture physics yields a prediction of strong containment, even for modest stress difference between pay and overburden. This agrees in general with average observed geometry, but in specific cases, fracture height growth still occurs, showing that in these cases the model was inadequate and needs to be calibrated. Pseudo-3D models tend to overestimate height growth for default inputs, but that can also be modified to match the stronger containment often seen in practice. Therefore, no benefit is obtained from fully gridded simulation models in routine cases where critical inputs and calibration data are unavailable.
Achieving Desired Fracture Placement in a Thick and Stratified Reservoir
Authors: Jaboob M.. , Turk G.A.. A. , Rylance M.. , Trejo R.. , Al-Shueili A.. , Al Manji A.. , Ishteiwy O.A.. A.
Published: October 2018

The Barik formation is a low-permeability conventional tight-gas reservoir, in Block 61 in the Sultanate of Oman, comprised of a series of interbedded sandstone and mudstone (shale) layers. To achieve the most efficient and economic development of this formation sequence, the wells require the application of massive hydraulic fracturing. Such an approach was developed and deployed during the Appraisal stage of the programme and a considerable effort was placed in ensuring that the fracture height was contiguous, resulting in an effective drainage across all layers of the Barik formation. This approach was then encapsulated in the Full Field Development (FFD) planning Basis of Design (BoD) and was established as the approach to be taken throughout FFD.

Until the field development was well underway, a single fracture treatment had proven sufficient to stimulate the entire Barik reservoir. However, as the development moved into the Southern area of the field, a substantial thickening of the Barik sequence was encountered and with this change successful complete vertical propped fracture coverage became much more challenging to achieve in an effective and repeatable manner. This paper demonstrates the approaches that were subsequently taken with the fracture design, the fracturing fluid selection and the fracture perforation strategy to address this issue and restore the achievement of complete fracture/formation coverage.

Throughout the paper a number of examples will be presented that demonstrate the issues and effects that arose with the thickening of the Barik formation. The paper will then go on to examine how these effects were identified, what surveillance was used and the various characteristics that were displayed and how they were inferred. It will examine how the various issues were addressed, what changes were made to the fracturing strategy and demonstrate, through direct results, the outcomes that were subsequently achieved.

This paper will focus on some of the principal issues that can arise when moving a developing fracture BoD in a laminated sequence into a more thickly developed environment with more extensive height and bulkier sands. The paper will provide a number of detailed examples of the issues themselves, and describe the detrimental and impactful effects that they may have on fracture coverage and hence well productivity and EUR. Additionally, the paper will describe the approaches that can be used in order to successfully address these effects. The paper will clearly demonstrate that when such considerations are taken into account that a successful suite of outcomes can be achieved.
Is Bigger Always Better? Using Chemical Tracers to Optimize the Size of your Multistage Fracturing
Authors: Spady D.. , Langdon I.. , Tippett W.. , Hogg M.. , Lane D..
Published: October 2018

From using history matching to recording microseismic; exploration, completion, and production groups in the oil and gas industry don't know exactly where stimulation treatments are placed and how efficient that placement has been. Exploration geologists and geophysicists want to know placement effectiveness to relate current geologic parameters with future potential formations. Completion engineers want to use tubular and downhole hardware systems to be as cost-effective as possible and to minimize total stimulation treatment cost. Production engineers are seeking to maximize production for as long a time frame as possible. Fracturing placement and verification cuts across all segments of an asset.

With recent technology and methodology advancements, the industry can inject particulate oilsoluble tracers (OST) with the proppant and measure those tracers effectively from fracture tip to production tank. While still not accurately describing the exact fracture geometry or parameters such as fracture conductivity (fcd), the industry can now qualitatively measure production from each stage. With each stage uniquely identified by post-fracture production, fracture size and capital expenditure associated with the placement of the fracturing treatment can be optimized.

Broadview Energy recently pumped a fracturing treatment into the 637 m (2089 ft) total vertical depth (TVD) Sparky clastic zone through a 114 mm (4.5") liner string in a horizontal wellbore using mechanically operated sleeves. Broadview Energy sequentially alternated the size of the fracturing treatments along the length of the well between 7.5 t (16, 534 lb) and 5 t (11,023 lb) of 16-30 fracturing sand as the proppant. Alternating the fracture size served to isolate geologic and fluid heterogeneities.

Measuring the OST concentration from each fracture treatment showed results that were not directly proportional with the size of the treatment; namely, a 50% larger stage treatment yielded a 33% improvement in OST return. Using tracer technology to show observable variations of completion methods, Broadview Energy hypothesizes that, with further testing, it would be possible to recognize the threshold in fracture size and prevent diminishing returns in future fracture treatments with similar geologic conditions.
Early Insights from Various Load Fluid Recoveries after Hydraulic Fracturing Treatments: A Case History of a Developing Unconventional Oil Shale Play in Alberta
Authors: Wüst Raphael A. , Mattucci Mike , Hawkes Robert , Quintero Harvey , Sessarego Sebastian
Published: October 2018

The Devonian Duvernay Formation in Alberta, characterized as a carbonate-siliceous source rock, is ramping up to be one of the largest and most prolific shale oil plays in Canada. In the southern part of the Duvernay Shale Basin (i.e. East Shale Basin), tight limestone beds are interbedded with laminated organic-rich calcareous shales, which show an organic maturity ranging mostly from early oil- to condensate-window. This new light oil shale play is still in the initial stages of development and the nature of these deposits requires hydraulic fracturing to increase stimulated rock volume. General completion programs involve ≥50 clustered plug ‘n’ perf stages with slickwater treatments in excess of 40,000 m3 with ~4000 tonnes of proppant per well. The large water volume treatments will inevitably interact directly with the rock surface in the stimulated area and cause both oil-water and rock-water interactions. Post-hydraulic fracturing water retention is especially pronounced in light oil shale plays. The oil-wet nature of the Duvernay, along with calcareous and siliceous shale lithologies, adds to the complexity of water retention and perceived water-blockage. In addition, because of operational delays such as road bans and pipeline constraints, some wells may be shut-in after the fracturing treatment for weeks and even months, which will affect rock-oil-water behavior (i.e. production). The extent of water displacing into the matrix of the rocks of the Duvernay Formation in the East Shale Basin, as measured by load fluid recovery, varies significantly and appears to heavily rely on the choice of surfactant. Although the use of surfactants is generally accepted for this play, detailed understanding of the rock-fluid interaction mechanisms is still incomplete.

This paper investigated the response of Duvernay Shale rocks from the East Shale Basin to various types of surfactants and analyzed production and fluid flowback data. Amott Cell analyses, which test for spontaneous oil displacement using various stimulation fluid types, demonstrated that in the East Shale Basin, nano-sized surfactants including multi-functional surfactants (MFS) and microemulsions significantly outperformed common surfactant chemistry when tested with mixed wettability shale core samples. The results provide an estimate as to extent of water migration into the matrix of the Duvernay as a result of the choice of surfactant. Our analysis is made possible from publicly available cores, laboratory analysis and high quality well production data from the Alberta Energy Regulator.
Multistage Hydraulic Fracturing Campaign Learning Curve in a Tight Sandstone Reservoir, Offshore West Africa
Authors: Sedda P.. , Parziale S.. , Giammancheri M.. , Forno L. Dal , Ferdinandi F.. , Farina L.. , Tsangueu B. E. , Giraud C.. , Morbelli D.. , Mauth K. D.
Published: October 2018

In the last decade, hydraulic fracturing has been successfully applied in West Africa for the development of tight reservoirs. Since 2007, more than 200 fracturing stages have been achieved in 9 different fields targeting wells characterized by a wide range of conditions: from sandstone to carbonate formations, from low to high temperature reservoirs, and from old existing completions to new drilled wells.

While applying this technology throughout the years, tailored solutions for treatments design have been continuously put in place to address the observed challenges and maximize the final oil recovery. The deployment of new technologies such as proppant flowback prevention additives, non-radioactive tracers for fracture height monitoring, and channel fracturing, to boost the fracture conductivity played a major role in achieving the desired results.

The accumulated in-depth knowledge on hydraulic fracturing built from local experience allowed Eni West Africa to rapidly approach a new offshore tight oil field development with confidence that hydraulic fracturing would be an effetive stimulation technique. This paper will describe the fracturing campaign major milestones, from the promising results obtained on the exploration wells, to the optimization actions implemented during the first development phase. Thus far, six horizontal and two vertical wells were completed, including a total of 23 hydraulic fracturing stages during a single campaign spanning less than one year.

On the first of the two vertical wells, each stimulated with a single frac stage, a non-radioactive tracer was employed for measuring the propped fracture height, and calibrating the frac model. For the horizontal wells, where 3 or 4 frac stages were implemented, a plug-and-perf (P&P) technique was selected. This method included coil tubing equipped with fiber optic, enabling precise perforation intervals placement, also providing flexibility in case re-perforation was required. Moreover, several actions were adopted to improve completion efficiency and cost-effectiveness, including perforation selection to limit near-wellbore pressure losses, and coiled tubing runs optimization for setting the bridge plug and perforating in a single trip.

Finally, particular focus will be given to the steep achieved learning curve, describing the adopted decisions, to improve both completion performance and fracture conductivity.
Fracture Design and Placement and Its Application and Influence on Amin Performance
Authors: Ishteiwy O. A. , Dawson W.. , Al Shidhani R.. , Al Busafi B..
Published: October 2018

The Amin formation is a tight sandstone formation, that is present in Block 61 in the Sultanate of Oman, that has presented a number of development challenges. The Amin reservoir is characterized by an average permeability approximately two orders of magnitude lower than the Barik formations, which is the other main current development reservoir within the field. Adding to the challenge is the presence of the immediately and extensively underlying Buah formation, which is known to be sour.

During the Appraisal phase of the project, two vertical wells and one horizontal well were completed in the Amin, demonstrating that a horizontal well profile with multi-stage fracturing would most likely be required to achieve consistently commercial rates. It was also evident, even during the project sanction, that significant further investigation would be required to be able to more completely understand the hydraulic fracture behaviour in the Amin; in terms of the created fracture geometry, appropriate hydraulic fracturing methodology, suitable formation connection techniques, and other completion design factors to succeed with a reservoir development. Additionally, it was known that understanding reservoir fluid distribution would be fundamental to delivering such wells.

During the Development phase several vertical wells were completed with a range of fracture types and designs, to facilitate an assessment of well performance in the vertical geometry, as well as understand the fracture height for various hydraulic fracturing techniques, including High Rate Water Fracturing (HRWF) treatments as well as Hybrid-Frac (HF) type approaches. Additionally, several horizontal wells were also completed to build upon the Basis of Design (BoD) that had been selected at the end of the Appraise phase, with a continuous learning approach taken to further develop the frac understanding. Lessons more recently learned from North American unconventional reservoir stimulations were also investigated, carefully selected and then subsequently applied in a coherent and systematic way.

This paper presents a review of several of these vertical wells and two horizontal wells, attempting to demonstrate the progress made between the approaches. Additionally, the two horizontal wells will be used as a case study to illustrate the application of the continuous improvement methods, as well as the adoption of some key appropriate technologies transferred from North American unconventional reservoir stimulation approaches. These included an investigation of perforation cluster efficiency, the baseline fracture design and fracturing fluid types; as well as integrating directly with the open-hole characterization and production logs to enhance the frac designs and results.
Successful Application of TSE-Based Fracturing Fluids in Proppant Fracturing for Unconventional Carbonate Source Rock
Authors: Al-Taq Ali A. , Al-Khaldi Mohammed H. , Alfakher Basil M. , Mechkak Karim
Published: October 2018

Fracturing operations consume relatively large amounts of fresh or groundwater, especially in the area of unconventional resources where multi-stage fracturing is required to obtain an economical production rate and improve recovery. In an attempt to conserve groundwater, treated sewage effluent (TSE) has been evaluated and optimized for fracturing treatments to provide the required transport property for the proppant and not induce formation damage by maintaining compatibility with formation brine. Extensive laboratory work has been conducted including viscosity measurements, compatibility testing, and a microbial study to optimize an TSE-based fracturing fluid for unconventional operations. Based on laboratory recommendations, the TSE-based fracturing fluid has been applied successfully on well-A.

Twenty stages of unconventional proppant fracture stimulation utilizing the Plug and Perf (P-n-P) technique across the carbonate source rock have been applied successfully. Two base fluids, freshwater and TSE, were used to evaluate the effectiveness of TSE as a substitute for the freshwater in unconventional fracturing operations. Each water was used in 10 stages. The post-fracturing production results of well-A showed comparable results with the offset wells treated only with freshwater-based fracturing fluids. The pressure logging tests (PLT) conducted on this well confirmed that contribution of intervals treated with TSE-based fracturing fluid was comparable with those treated with fresh water-based fracturing fluid. There was no evidence of scaling issues during the flowback period for both fluid systems. Microbial evaluation of water samples collected during the flowback of well-A showed no presence of bacteria in these samples. This paper will discuss the laboratory work and the field application of TSE-based fracturing fluid.
ACA Practical Considerations: When is it Accurate and How Should it be Used to Improve Reservoir Stimulation
Authors: Ishteiwy O. A. , Jaboob M.. , Turk G.. , Dwi-Kurniadi S.. , Al-Shueili A.. , Al-Manji A.. , Smith P..
Published: October 2018

The use of the Diagnostic Fracture Injection Test (DFIT) technique as a means of pre-frac investigation has become relatively routine in the oilfield, particularly to understand the reservoir properties and then subsequently optimize the hydraulic fracture design. A key component of an effective DFIT is the performance of an effective After Closure Analysis (ACA) to assess the transmissibility of the formation and thereby allow for effective design.

BP Oman is developing the Barik formation, within the Khazzan field, which is a low-permeability conventional tight-gas reservoir within Block 61 of the Sultanate of Oman. The reservoir is comprised of a series of tightly interbedded sandstones and shales, with substantial shale breaks between the principal sand lobes. During the Appraisal and Development well sequence to date, BP Oman have performed DFIT operations in over 50 vertical wells, within the Barik Formation. Each one of these wells was then subject to placement of a large (one million lb) hydraulic fracture treatment. Each treatment was then followed by a standard clean-up programme and when possible a PBU, with subsequent placement on production into the main gathering system.

This paper seeks to demonstrate that there is unambiguous evidence of a coherent correlation between the petro-physical Barik open-hole logs, the transmissibility value (as estimated from the ACA), the conventional Pressure Transient Analysis (PTA) as well as the long-term production behaviour. Additionally, the paper will investigate the key aspects of the actual DFIT execution, the data gathering and the analysis that can impact the quality of the correlation. The paper will go on to demonstrate the most efficient methods of achieving the most accurate assessment of the formation transmissibility; that is both indicative and subsequently helpful for the fracture design and post-fracture productivity prediction.

This paper successfully describes a 50 well, and growing, DFIT analysis programme and the suitability of the use of the results from the subsequently performed ACAs for forward planning and hydraulic fracture design. Providing a suite of useful and helpful insights, suggestions and recommendations; into how DFIT, for ACA, should be executed in the field; the paper adds an extensive case history to the industry database for future consideration.
Unconventional Multiplay Evaluation of Casing-in-Casing Refracturing Treatments
Authors: Cadotte R. J. , Elbel Brittany , Modeland Neil
Published: October 2018

Throughout the development of major shale plays, a better understanding of stimulation influence on reservoir productivity has led to significant changes in industry completion practices. The relatively fast development of fields combined with the evolution of completion design suggests the completions performed on the earlier completed wells are understimulated and inadequate for optimum recovery. In the Eagle Ford and Haynesville shales, refracturing treatments were first performed using degradable particulate diversion, but yielded inconsistent results. However, a new method using the installation of a new casing string has been applied to these two separate plays to help reduce risk and maximize asset production.

Precise placement of the restimulation treatment using degradable particulate diversion is complex because of a lack of treatment isolation. The fluid used in restimulation must overcome friction pressure differentials, the presence of several existing perforations, and reservoir depletion. Advancements in cement slurries and wellbore design have made it possible to install a new, smaller casing string into the existing wellbore and restore treatment isolation. Despite the tight annular clearances, a specialized slurry has been designed to maintain circulation and to provide good mechanical properties for proper zonal isolation.

The reconstruction of the wellbore with the smaller casing string enables the refracturing treatment to be performed like new-drill completions by means of plug-and-perforate methodology. Although the treatment injection rate might be limited in comparison, many of the complications in diversion refracturing treatments are eliminated. This process has confirmed greater repeatability and more consistent production results across two separate plays.

The successful implementation of 75 casing-in-casing refracturing treatments in the Haynesville resulted in an average estimated ultimate recovery (EUR) increase of approximately 150%. This technique has been implemented in the Eagle Ford and, although the number of wells in the dataset is fewer, the EUR of some wells observed have experienced an average increase of 140%. This method is becoming increasingly popular, with multiple operators successfully applying this technique throughout different portions of the Haynesville and Eagle Ford Shale.
Development Strategy Optimization of Ning201 Block Longmaxi Shale Gas
Authors: Yong Rui , Wu Jianfa , Shi Xuewen , Zhuang Xiangqi , Wen Heng , Luo Yin
Published: October 2018

Changning National Shale Gas Demonstration Area was established in 2012. Field Development of its Ning201 shale gas fields was geared up in 2014. By 2015, Changning area accomplished the construction of 15×108 m3/a production capacity. During early appraisal phase before 2014, average testing results of wells were 10~15×104 m3/d. In the end of 2016 and early 2017, average testing results of large numbers of wells across multiple pads achieved over 25×104 m3/d. Overall testing results of some pads have exceeded 180×104 m3/d per pad, and some of them may exceed 180×104 m3/d per pad in soon future. Through implementing geo-engineering integration, efficiency and effectiveness of field development have been steadily enhanced. This paper reviews our practices to establish and rapidly evolve the learning curve in this national demonstration area through geoengineering integration. Benefiting from geo-engineering integrated study, development options were systematically, proactively and effectively supported throughout the process of field development. Per the evolving understanding of reservoir and engineering challenges, adaptive technology and engineering solutions were exploited and optimized. A new geo-engineering model has been proposed which covers engineering applications of drilling, completion, production and development. Based on our gathered knowledge and experience, key contributing factors for marine shale gas development in Sichuan basin were thoroughly studied and summarized. They may include controlling factors of productivity, optimum production scheme, optimized well spacing, and so on. This paper also points out key areas for further improvement and enhancement in future.
Investigation of Multiple Hydraulic Fracture Propagation for Low-Pressure Tight Sandstone Reservoirs in Northern Ordos Basin of Changqing Oilfield, China
Authors: Tang Jizhou , Ehlig-Economides Christine , Li Jiawei , Guo Xuyang , Wu Kan , Mu Lijun , Tang Meirong , Du Xianfei
Published: October 2018

Giant Ordos basin, located in the northern China, consists of Palaeozoic lacustrine stacked sandstone and shale deposits characterized by low-pressure, low-porosity, low permeability matrix rock and a poorly developed natural fractures (NFs) system. Recognizing the successful exploration of shale gas reservoirs in United States, Changqing oilfield primarily uses three fracturing technologies, hydraulic sandblasting technology, open-hole packer technology and drillable bridge plugging technology, to create multiple straight hydraulic fractures (HFs) in tight sandstone zones with large differential horizontal stress. For this study we consider multiple perforation clusters per stage using the drillable bridge plugging technology, which offers benefits of large injection rate and high treatment efficiency. This paper describes a hydraulic fracture propagation model (HFPM) that couples fracture deformation and fluid flow to simulate the growth of multiple HFs in the horizontal wellbore. We then integrated an embedded discrete fracture model (EDFM) and commercial reservoir simulator to analyze production prediction based on the provided data from Changqing oilfield. We calibrated the fracture propagation model with the reservoir performance data and demonstrated how to optimize the fracture treatment. The low formation pressure gradient in the Changqing oilfield impairs the production performance. To reduce the rapid decline rate in reservoir pressure, the fracturing fluid is not only used for creating fractures, but also enhancing the pore pressure by leaking off into the formation. Adjusting the pumping rate and fluid volume enables our model to increase the formation pressure gradient. Moreover, the tight sandstone deposits in the Changqing oilfield have a relatively high brittleness index (BI) and large differential horizontal stress. This is the reason why reservoir with sparse NFs in the Ordos basin has less opportunity of generating complex fracture networks. Large-scale physical simulation experiments were also conducted to validate the possibility of fracture networks generation. Our model accouts for the stress heterogeneity and offers the capability to address HF propagation in the presence of sparsely distributed NFs and adjusts the dimensions and spacing of the NFs to achieve a history match with production data. This paper emphasizes the extensive application of a fracture propagation model for lacustrine tight sandstone deposits. Considering features of Ordos basin, such as low-pressure gradient and relatively high BI, our model can provide a guideline for HF treatment design and optimization of well performance.