1,720,976 research outputs found
Laboratory experiment based permeability reduction estimation for enhanced oil recovery
No full textFormation damage is an unwanted operational problem-taking place through
several phases of oil reservoir life. The permeability reduction is a key indicator
for the formation damage. Suitable assessment of permeability reduction is
critical for hydrocarbon recovery. As oil production reach tertiary recovery stage
in many fields, formation damage critical evaluation is needed to avoid additional
operational cost and technical feasibility concern. The interaction between
reservoir minerals and chemical injection practices is not fully understood. Also,
clay mineral presence is highly sensitive to the chemicals, while adsorption
phenomena can also occur. The degree of permeability reduction cannot be
generalized for core/field scalestherefore investigating the permeability
reduction in core scale is important before field-scale assessment. Therefore, this
study investigates the permeability reduction after chemicals injection under low
flow rate in sand-quartz cores and in the presence of kaolinite. Artificial
sandpacks were used to control the sand-kaolinite mixture percentage. The
permeability was measured before and after each flood by pressure drop
calculation. The study showed that the seawater flood has the highest reduction
in permeability followed by polymer and surfactants. Also, the results showed a
strong effect of surfactant nature and molecular weight on the adsorption process
and consequently the permeability reduction. The study provides an insight for
the effect of chemicals on cores physical properties
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Evaluation of Flaxseed Hydrocolloid’s Potential in Improving Oil Recovery
No full textThe use of natural materials to improve oil recovery and production is believed to be a suitable method. The current study examined hydrocolloids extracted from flaxseed as a viscosifying agent for improved and enhanced oil recovery EOR. It aimed to investigate the effect of concentration, temperature, salinity, and ageing time on the rheology of the flaxseed gel solution (FGS). The study also highlighted the solution’s performance at the core level for carbonate reservoirs. The FGS was successfully extracted by soaking and heating at 70 °C. Fourier-transform infrared (FTIR) spectroscopy results showed polysaccharide dominance in the mucilage. The rheology outcomes showed that the FGS was able to increase the water viscosity by 5–17 cp at 25 °C. Different concentrations of the FGS preserved its viscosity at temperatures of 25–45 °C. The salinity reduced the gel’s viscosity, especially above 2.5 wt%. A 50 g/L solution successfully tolerated all the tested salinities and the temperature range at all shear rates. A reduction in viscosity was observed during the first five days of ageing due to biological degradation caused by bacteria. Ageing had no major influence between 5 and 10 days. The FGS resulted in a 12 % incremental oil recovery. The sweep efficiency improved due to the 84 % mobility enhancement. This study confirms the possibility of deploying hydrocolloids as a natural viscosifier to improve the oil recovery in Kazakhstan’s oil reservoir conditions
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