bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New-Intermediate Strength Proppant Additive to Combat Asphaltene Deposition for Delivering Long Term Flow Assurance
Authors: Bestaoui-Spurr Naima , DeBenedictis Frances , Usie Marty , Bhaduri Sumit 
Published: February 2020

Abstract
Conventional asphaltene inhibitor treatments prevent asphaltene deposition in the production string and near the wellbore. However, these liquid injection treatments provide little to no protection deep into the reservoir. A new proppant like slow release asphaltene additive that is mixed with the proppant provides the possibility for long term flow assurance without conductivity impairments. This substrate allows more chemical to be transferred bottomhole resulting in longer treatments.
Traditional and nontraditional screening methods were used to demonstrate the longevity of the intermediate strength proppant like slow release asphaltene additive. The additive release profile was evaluated in a mixture with proppant and using untreated crude oil. Long-term protection was then determined. Furthermore, the proppant like substrate was characterized for its proppant like characteristics using API standards. Conductivity studies, to ensure the additive did not affect the proppant pack negatively, and fracturing fluid compatibility were also performed.
The results show that the proppant like slow release asphaltene additive has no conductivity losses at increased loadings and can provide a cost effective long-term flow assurance solution and can be used in the same range than an intermediate strength (ISP) proppant. Significant numbers of Gulf of Mexico (GoM) wells experience closure stresses in the range for the ISP product, opening up the possibility of using this product in this stress regime. Presence of asphaltene inhibitor in the deepest part of the fracture allows release of the chemical and resulting in reduction of precipitates and lowered conductivity damage to plugging. Controlled release of the chemical from the ISP like substrate allows only a certain amount of chemical needed for inhibitor control, preserving the rest of the inhibitor for subsequent release. The incorporation of a delay mechanism in the slow release asphaltene additive will provide increased protection as the well ages. This method allows longer protection time and affords a more cost-effective treatment.
Mineral Solubility Measurement and Prediction Under High Pressure, High Temperature Reservoir Conditions
Authors: Goodwin Neil , May Mark , Wilson Sam , Graham Gordon 
Published: February 2020

Abstract
Being able to predict formation damage due to near-wellbore scale deposition relies on accurate scale prediction modelling. It is recognised that the relative paucity of HPHT solubility data can result in inaccurate predictions, as current models typically extrapolate from solubility data obtained on simple systems under more conventional conditions. This paper describes the generation of additional fundamental solubility data under HPHT conditions, and compares the obtained values with several existing models.
A purpose-built laboratory test rig capable of making mineral solubility measurements up to 250 °C and 25,000 psi has been used in this work. Experimental methodology has been developed using calcium sulphate to demonstrate that equilibrium conditions have been reached. In this work, barium sulphate solubility data has been generated at conditions up to 200 °C and 20,000 psi in the presence of calcium or magnesium ions, as it was recognised that available data for oilfield-representative brines under such conditions was limited. Scale prediction modelling has been conducted using a range of software widely used in the industry to assess the accuracy of the models in these circumstances.
Results for calcium sulphate solubility, obtained earlier, indicated the importance of validating the test methodology, not just for each mineral but also under the required temperature and pressure, to verify that equilibrium solubility conditions have been achieved. Barium sulphate solubility increases with the addition of other divalent cations, but the extent of the increase is at present not accurately predicted by existing scale prediction models. In some cases, the predicted barium sulphate solubility was up to three times greater than the experimentally determined value. It is apparent that there is considerable scope for improvement of scale prediction models under HPHT conditions, particularly in complex brines systems, and that further fundamental solubility data is required to facilitate this.
This paper provides additional data for mineral solubility under HPHT conditions with more complex brines, which are more representative of those produced in oilfields. The work demonstrates the limitations of existing scale prediction modelling software under HPHT conditions, particularly in the presence of significant concentrations of other divalent cations, and illustrates areas where additional data and model development are critical to enable more accurate modelling of scaling risk.
Unplugging Standalone Sand Control Screens with High-power Shock Waves: An Experimental Study
Authors: Habibi Ali , Fensky Charles , Perri Mike , Roostaei Morteza , Fattahpour Vahidoddin , Mahmoudi Mahdi , Ghalambor Ali , Sadrzadeh Mohtada , Zeng Hongbo 
Published: February 2020

Abstract
Previous studies showed that different parameters influence the plugging of completion tools. These parameters include (i) rock mineralogy, (ii) reservoir fluids properties, and (iii) type of completion tools. Although different methods have been used for unplugging these tools, there is still debate regarding performance of these methods on damage removal.
In this study, we assessed the performance of high-power shockwaves generated from an electro-hydraulic stimulation (EHS) tool on cleaning completion tools plugged during oil production. These devices were extracted from different wells in Canada, Europe, and the US. First, we evaluated the extent of cleaning for the plugged completion tools using an EHS tool at the lab-scale. We examined the slots/screens before and after the treatment to show the performance of the EHS tool. Next, we analyzed the mineral composition and morphology of the plugging materials removed after the treatment by conducting X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Spectroscopy (EDS) analyses. Finally, we reviewed the pulsing stimulation treatment results applied to several field case studies.
The results of unplugging sand control devices at the lab-scale showed that more than 50% of plugged slots/screens were cleaned after 45 pulses of shockwaves. The characterization results showed that the main plugging materials are calcite, silicate, and iron-based components (corrosion products). The results of field case studies showed an improved oil production rate after the pulsing stimulation treatment.
This paper provides a better understanding of the performance of shockwaves on damage removal from plugged completion tools. The results could provide a complementary tool for production engineers to select a proper method for treating the plugged tools.
A Novel Shifting Tool to Operate Formation Isolation Valves
Authors: Balasubramanian Ganesh 
Published: February 2020

Abstract
Subsurface barrier valves such as a formation isolation valves (FIVs) isolate the formation from the production bore after the first perforation and the lower completion has been installed. This enables installation of the upper completion and in some cases multiple perforation runs before the well starts producing. During this time, they protect the formation from fluid loss and pressures by acting as a bi-directional fluid barrier. In addition to reduced rig time, a key advantage of FIVs is reduced intervention costs. FIVs can be openend and closed multiple times as required, mechanically with an intervention tool such as a primary shifting tool (PST) (Fig. 1). The conveyance method for PSTs can be on coiled tubing, work string, perforating string, or wireline (using a tractor and stroker) to open and close FIVs. PSTs then must reliably engage and release from shifting profiles in the FIVs to operate the valve and release from the profile after successful valve actuation.
Hence design of the PST is critical for relaible FIV operation. In the event of an emergency where the shifting profile in the tool is unable to release from the engaging profile in the FIV, it is critical to have an emergency release feature inherent in the PST that can enable release of the tool yet not damage the FIV. A novel methodology was developed to design PSTs to enable emergency release if required, through controlled plastic deformation at loads below work string shear limitation. This methodology also avoids fracturing of PST components as free-hanging pieces could be caught in the wellbore while pulling out the tool from the well after emergency release.
Nanocellulose as a New Degradable Suspension Additive for High-Density Calcium Brines
Authors: Deville Jay P. , Rady Ayten , Zhou Hui 
Published: February 2020

Abstract
Calcium-based brines, principally calcium chloride and calcium bromide, find widespread use as completion fluids and base fluids for reservoir drill-in fluids (RDF). The high ionic strength of these brines, combined with the chemical compatibility issues inherent with divalent ions, such as calcium, makes identifying additives for developing functional fluids challenging. While additives, such as hydroxyethyl cellulose, can provide viscosity to calcium brines, imparting the suspension properties needed for the transport of solid bridging agents or drill cuttings can be particularly problematic in divalent brines. Even the widely used and potent suspension agent, xanthan gum, in addition to being difficult to degrade, suffers from gelation and precipitation under certain conditions in high-calcium environments. In this study, nanocellulose, which has previously shown promise as a suspension additive in freshwater and low-salinity brines, was evaluated in high-density brine fluids.
Extensive laboratory evaluation of the commercially sourced nanocellulose was conducted in sodium chloride, calcium chloride, and calcium bromide brines. Rheological determinations were made of simple systems containing only brine plus the novel additive, as well as fully formulated RDF containing the additive with sized calcium carbonate bridging solids, alkalinity, and filtration control additives. This data was compared before and after aging at various temperatures and was further compared to other biopolymers that are used today in divalent brines. Stability of the fluids and the capability of the formulated fluids to suspend solids were also examined. Fluid-loss control of full formulations was compared under API conditions. Single-phase return permeability studies were conducted.
While results in sodium brines were mixed, nanocellulose was shown to outperform existing biomaterials in calcium brines. Nanocellulose was shown to be readily hydrated in the challenging high-density divalent environment and provided superior suspension to currently used fluid components at similar concentrations. Rheological performance of nanocellulose was found to be synergistic with bridging solids. In one particularly interesting example, it was also shown to complement a synthetic polymer in a high-temperature calcium bromide application.
Nanocellulose provides superior rheological performance and reduced formation damage potential compared to conventional materials in difficult high-density calcium chloride and bromide brines. The improved rheological profile and enhanced thermal stability of fluids formulated with nanocellulose, combined with a greater diversity of removal options, can facilitate expansion of the utility of calcium-based brines in well construction and completion applications.
Application of New Technologies to GoM for a Successful Open Hole Gravel Pack
Authors: Rodrigues Kegan , Kevin Whaley , Lawrence Ramnath , Kerimov Natig , Henry Ivan , Brune Lehron , Spicer Jared , Nwafor Chidi , Gutierrez Carlos , Filbrandt Joseph 
Published: February 2020

Abstract
This paper highlights the new drilling and completion technologies used in the delivery of the company’s first successful horizontal open hole gravel pack (OHGP) in the deep-water Gulf of Mexico (GoM). The well was drilled and completed with well performance exceeding the planned objectives.
A new drilling fluid system was needed to address the high depletion, minimize formation damage, and manage the wellbore stability challenges associated with depleted horizontal drilling stress anisotropy. A brine-based system inclusive of a reservoir drill-in fluid (RDIF), solids free screen running pill, and displacement push pill, were qualified. Managed pressure drilling (MPD) was employed to manage the drilling of depleted sands, and managed pressure cementing (MPC) was used for cementing across narrow frac gradient (FG) windows, a new application for the company. New real time drilling surveillance was also applied to allow for trajectory optimization and maximining the open hole (OH) length.
For the completion, a new high temperature gravel pack (GP) carrier fluid was developed to meet the high reservoir temperature and pressure requirements. This GP fluid was also designed to break on surface using an optimized breaker system, allowing for full capture with zero discharge. The sandface completion system included a new to GoM shunted wire wrap screen (WWS), y-manifold, and new lower completion hardware including an anti-swab GP service tool. New completion open hole displacement and GP procedures, to include a new skid-based GP pumping technique, were also implemented successfully.
Medical career expectations of academically talented high school students: A nationwide cross-sectional study in China
Authors: Wu Hongbin , Pei Leisi , Li Shan , Jiang Cheng 
Published: February 2020

Abstract
Background: Academically talented high school students (ATHSSs), an exceptional cohort, are not well studied for their career expectations, especially for those with medical career expectation (MCE). Nowadays, the public perception of the medical profession is changing in China. The purpose of this study was to answer questions about ‘is medicine attractive for ATHSSs and ‘what factors affect medical career expectations (MCE) for ATHSSs’ in China. Methods: A total of 16,479 representative ATHSSs in senior three completed a questionnaire and four different academic tests. Frequency statistics showed the proportion of ATHSSs with MCE. Unpaired t-tests were performed to find out the differences in demographics, family background, and academic performance between students with and without MCE. The logit models analysis were applied to explore the potential factors that affected the MCE of this exceptional group of students. Results: ATHSSs with MCE accounted for 20.6% (ranking 7/18) of the respondents. They were more likely to be female, came from relatively poorer families, lived in a rural area, and performed significantly worse in all academic tests except for mathematics, compared with those without MCE. In addition, the results revealed that gender (β=-0.436, p<0.01), region of hometown (β=-103, p<0.1), mother’s years of schooling (β=-0.019, p<0.05), and father’s occupational status (β=-0.005, p<0.01) contributed significantly to the MCE of academically talented students. Better performance in mathematics affected the MCE of ATHSSs taking the liberal arts and science tests differently. Conclusions: We found the medical career is becoming unattractive to academically talented students and the medical career may be loosing their aura in China. Students who have medical career expectations are likely to be females and to have a weak family background. We discuss implications for medical education.
Prevalence and determinants of modern contraceptive utilization among rural lactating mothers: Findings from the primary health care project in two northwest Ethiopian districts
Authors: Derso Terefe , Biks Gashaw Andargie , Yitayal Mezgebu , Ayele Tadesse Awoke , Alemu Kassahun , Debalkie Getu , Fekadu Hailab , Dellie Endalkachew , Azale Telake , Misganaw Bisrat , Kebede Adane , Fetene Destaw , G/medhin Tsegaye , Atnafu Asmamaw 
Published: February 2020

Abstract
Background : Contraceptive utilization is a guarantee to avert unwanted pregnancies. In Ethiopia however, more than half of the rural women have shorter birth intervals. Consequently, 17% and 8% of the births have been either mistimed (wanted at later date) or unwanted, respectively. Therefore, this paper investigated modern contraceptive utilization and its predictors among rural lactating women. Methods : A community based-cross-sectional study was conducted from May 01 to June 29, 2019, in Dabat and Gondar zuria districts, northwest Ethiopia. Data from 603 lactating mother were collected through face to face interviews using a structured questionnaire. Bivariate and multivariate logistic regression analyses were done to identify the independent predictors of modern contraceptive utilization. Results : The overall prevalence of modern contraceptive (MC) utilization rate was 45.8% [95% CI: 38.01, 53.59]. The contraceptive method mix was dominated by Depo-Provera (39.8%) followed by implants (4.8%). The odds of utilization of contraceptive were 5.58 times higher among mothers of children with fully immunized [AOR=5.58, 95% CI: 3.45, 9.01] compared to mothers whose children were vaccinated partially or not at all. Mothers who received antenatal [AOR= 1.743, 95% CI: 1.13, 4.43] and postnatal care [AOR=2.02, 95%CI: 1.24, 2.91) were 1.74 and 2.02 folds more likely to utilize modern contraceptives than mothers who did not receive such care, respectively. Conclusion : The prevalence of modern contraceptive utilization in own study area was lower than the planed national target. In the region, child immunization service is one of the promising platforms for reaching lactating mothers with modern contraceptive utilization. Our findings suggest that antenatal and postnatal care visits are the other key determinants of modern contraceptive utilization. Thus, in low-resource settings like ours, the health system approaches to improved antenatal and, postnatal care and child immunization services should be intensified with more effective advice on modern contraceptive utilization to reduce unwanted pregnancies. Key words : Contraceptive utilization, Postnatal care, Child immunization
Shedding light: A phylotranscriptomic perspective illuminates the origin of photosymbiosis in marine bivalves
Authors: Li Jingchun , Lemer Sarah , Kirkendale Lisa , Bieler Rüdiger , Cavanaugh Colleen , Giribet Gonzalo 
Published: February 2020

Abstract

Background Photosymbiotic associations between metazoan hosts and photosynthetic dinoflagellates are crucial to the trophic and structural integrity of many marine ecosystems, including coral reefs. Although extensive efforts have been devoted to study the short-term ecological interactions between coral hosts and their symbionts, long-term evolutionary dynamics of photosymbiosis in many marine animals are not well understood. Within Bivalvia, the second largest class of mollusks, obligate photosymbiosis is found in two marine lineages: the giant clams (subfamily Tridacninae) and the heart cockles (subfamily Fraginae), both in the family Cardiidae. Morphologically, giant clams show relatively conservative shell forms whereas photosymbiotic fragines exhibit a diverse suite of anatomical adaptations including flattened shells, leafy mantle extensions, and lens-like microstructural structures. To date, the phylogenetic relationships between these two subfamilies remain poorly resolved, and it is unclear whether photosymbiosis in cardiids originated once or twice. Results In this study, we establish a backbone phylogeny for Cardiidae utilizing RNASeq-based transcriptomic data from Tridacninae, Fraginae, and other cardiids. A variety of phylogenomic approaches were used to infer the relationship between the two groups. Our analyses found conflicting gene signals and potential rapid divergence among the lineages. Overall, results support a sister group relationship between Tridacninae and Fraginae, which diverged during the Cretaceous. Although a sister group relationship is recovered, ancestral state reconstruction using maximum likelihood-based methods reveals two independent origins of photosymbiosis, one at the base of Tridacninae and the other within a symbiotic Fraginae clade. Conclusions The newly revealed common ancestry between Tridacninae and Fraginae brings a possibility that certain genetic, metabolic, and/or anatomical exadaptation existed in their last common ancestor, which promoted both lineages to independently establish photosymbiosis, possibly in response to the modern expansion of reef habitats.
Heat-Not-Burn Tobacco, Electronic Cigarettes, and Combustible Cigarette Use Among Japanese Adolescents: A Nationwide Population Survey 2017
Authors: Kuwabara Yuki , Kinjo Aya , Fujii Maya , Imamoto Aya , Osaki Yoneatsu , Jike Maki , Otsuka Yuichiro , Itani Osamu , Kaneita Yoshitaka , Minobe Ruriko , Maezato Hitoshi , Higuchi Susumu , Yoshimoto Hisashi , Kanda Hideyuki 
Published: February 2020

Abstract
Background
From among the global public health concerns, smoking remains one of the most crucial challenges. Especially for adolescents, the increase in the use of electronic cigarettes is controversial, as its use may lead to established smoking. In Japan, where a unique tobacco regulation system exists, the heat-not-burn tobacco market has been growing. However, the prevalence and association of combustible cigarettes and new tobacco-related products have not yet been closely investigated among Japanese adolescents. This study aimed to clarify the prevalence of smoking among adolescents, including new types of tobacco-related products, and to compare the characteristics of their users.
Methods
The 2017 Lifestyle Survey of Adolescents is a nationally-representative survey collected in Japan. From the national school directory, 98 junior high schools and 86 high schools were randomly sampled throughout Japan. The students completed an anonymous questionnaire at school. We calculated the prevalence of use for each type of tobacco product. Then, the use of a combination of products and the characteristics of different types of products were examined.
Results
In total, 64,152 students from 48 junior high schools and 55 high schools were included the analysis (school response rate = 56%, M age = 15.7 years, 53.9% boys). The age-adjusted rate of ever (current) use of electronic cigarettes was 2.1% (0.7%) in junior high school and 3.5% (1.0%) in high school; that of combustible cigarettes was 2.6% (0.6%) in junior high school and 5.1% (1.5%) in high school. The rate of heat-not-burn tobacco use was lower relative to other products: 1.1% (0.5%) in junior high school and 2.2% (0.9%) in high school. An examination of the combined use of the three products identified a high number of dual users. Comparisons between different types of users indicated different backgrounds for combustible cigarette users and new product users.
Conclusions
The prevalence of new tobacco-alternative products is growing in popularity among Japanese adolescents. Dual use is common, and many adolescents use new products only. Moreover, e-cigarettes might attract a broader range of groups to smoking. Continuous monitoring and research are needed to investigate their influence as a possible gateway to tobacco smoking.