745 research outputs found
Experimental Study on a Novel Foaming Formula for CO2 Foam Flooding
This research developed a viable and economical foaming formula (AOS/AVS/N70K-T) which is capable of creating ample and robust CO2 foams. Its foaming ability and displacement performance in a porous medium were investigated and compared with the two conventional formulations (AOS alone and AOS/HPAM). The results showed that the proposed formula could significantly improve the foam stability without greatly affecting the foaming ability, with a salinity level of 20,000 ppm and a temperature of 323 K. Furthermore, AOS/AVS/N70K-T foams exhibited thickening advantages over the other formulations, especially where the foam quality was located around the transition zone. This novel formulation also showed remarkable blocking ability in the resistance factor (RF) test, which was attributed to the pronounced synergy between AVS and N70K-T. Last but not the least, it was found that the tertiary oil recovery of the CO2 foams induced by AOS/AVS/N70K-T was 12.5% higher than that of AOS foams and 6.8% higher than that of AOS/HPAM foams at 323 K and 1500 psi, thus indicating its huge enhanced oil recovery (EOR) potential. Through systematic research, it is felt that the novel foaming formulation might be considered as a promising and practical candidate for CO2 foam flooding in the future
An experimental study of combined foam/surfactant polymer (SP) flooding for carbone dioxide-enhanced oil recovery (CO2-EOR)
To better address the issue of viscous fingering and gravity segregation confronted in CO2 flooding, a novel EOR method which coupled the SP flooding with the CO2 foam flooding was presented. Its displacement performance was systematically evaluated and compared with the other two injections modes (i.e. direct foam flooding and CO2/SP flooding) which applied the same amount of the gas and chemicals as the proposed mode. It had been found, if the injection pressure enabled the oil/CO2 miscibility to occur, the foam/SP flooding was endowed with the highest blockage and lowest water cut. Moreover, its oil recovery factor was 5.8% and 12.6% greater than that of direct foam CO2/SP flooding respectively; on the other hand, if the injection pressure was below the minimum miscibility pressure (MMP), the direct foam flooding and the SP flooding displayed comparable water cut and oil recovery factor. Although the foam/SP flooding still recovered the most crude oil, it was only 3.7% and 6.8% higher than that of the direct foam and SP flooding respectively, indicating the less evident displacement advantage. It was believed that the proposed method possessed huge EOR potential, especially in the reservoir whose pressure was well above the MMP
Distributed Holistic Clustering on Linked Data
Link discovery is an active field of research to support data integration in
the Web of Data. Due to the huge size and number of available data sources,
efficient and effective link discovery is a very challenging task. Common
pairwise link discovery approaches do not scale to many sources with very large
entity sets. We here propose a distributed holistic approach to link many data
sources based on a clustering of entities that represent the same real-world
object. Our clustering approach provides a compact and fused representation of
entities, and can identify errors in existing links as well as many new links.
We support a distributed execution of the clustering approach to achieve faster
execution times and scalability for large real-world data sets. We provide a
novel gold standard for multi-source clustering, and evaluate our methods with
respect to effectiveness and efficiency for large data sets from the geographic
and music domains
Antioxidant activity of the methanolic extracts of some species of Phlomis and Stachys on sunflower oil
Antioxidant effects of the methanolic extract of Phlomis bruguieri, P. herba-venti, P. olivieri, Stachys byzantina, S. inflata, S. lavandulifolia and S. laxa were tested in sunflower oil stored at 70ºC, by measuring peroxide values after regular intervals and compared with rosemary-, green tea- and BHAcontaining samples. The methanolic extracts of P. bruguieri and S. laxa were found to be most effective in stabilizing sunflower oil
Synthesis and Optimization of Reversible Circuits - A Survey
Reversible logic circuits have been historically motivated by theoretical
research in low-power electronics as well as practical improvement of
bit-manipulation transforms in cryptography and computer graphics. Recently,
reversible circuits have attracted interest as components of quantum
algorithms, as well as in photonic and nano-computing technologies where some
switching devices offer no signal gain. Research in generating reversible logic
distinguishes between circuit synthesis, post-synthesis optimization, and
technology mapping. In this survey, we review algorithmic paradigms ---
search-based, cycle-based, transformation-based, and BDD-based --- as well as
specific algorithms for reversible synthesis, both exact and heuristic. We
conclude the survey by outlining key open challenges in synthesis of reversible
and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table
A Method to Relate the Affecting Parameters and Estimate Dilution in Coal Mines
This study provides an overview of the various issues influencing Out-of-Seam Dilution (OSD) in longwall mining method. The collected data has been statistically analyzed to examine the effect of the some factors causing OSD in front of the longwall mining face. Multiple parameter regression analysis was conducted on affecting parameters and the OSD. The SPSS (Statistics Package for Social Sciences) for Windows software package was used for the statistics analysis. Finally, a relationship between affecting parameters and the OSD is established by using the multiple parameter regression results. Results of this study have revealed that depth of seam, dip of seam, roof quality and variation in seam thickness are the most important influence factors for OSD. The proposed method may be utilized for the estimation of OSD for similar mines since, it was based on actual collected data from the coal mines
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