Performance of Air Foam Flooding under Low Frequency Vibration

Foam injection is widely applied in amounts of fields to drilling, production, and formation protection. Sometimes, the application result is disappointing, which is caused by the failure of bubble generation in foam flooding. Therefore, it is necessary to seek ways for improving the performance of foam injection. An increased disturbance to the stratum, like the vibration caused by a seismic oil recovery technique, would be helpful. In the current work, the seepage of air foam in porous media under low frequency (LF) vibration is analyzed with experiments and an investigation of bubble creation/destruction rate change is carried out using mathematical modeling. The resistance factor of foam flooding under indoor vibration increases by 1.5 times and the valid time is obviously extended compared with when no vibration is used. The optimal vibrating acceleration and frequency of 0.7 m/s2 and the natural frequency of the cores-nearby of 18 Hz are achieved in the indoor experiments. Under vibration, the bubble generation rate increases, while bubble break rate by internal expansion or by gas diffusion and transfer decreases. An interesting phenomenon is also observed, which might develop a power level formula between the initially defined dimensionless MRF (maximum foam flooding resistance factor) and dimensionless DMRF (duration of maximum foam flooding resistance factor). The power product and sum of the power exponents of the above formula both equal approximately to 1. With the assistance of LF vibration, the increase of security, adaptability, and efficiency in foam injection may improve the reservoir recovery and extend its application.</span

The Analysis of Hydrates Frozen Blocking in Fire Flooding Exhaust Gas of Heavy Oil

The No. 56 desulfurization tower pipeline network of Dawn production plant in Liaohe Oilfield is fire flooding exhaust gas collecting pipe. Since put into production, because of the large amount of gas and liquid, fine pipelines and big quantities of bends, the frozen blocking often occurs in winter. The site only adds methanol inhibitors on the basis of production experience, although the frozen blocking phenomenon is eased, it also shows frozen blocking phenomenon in the well interchanges and ups and downs. Now aiming at the problem, based on the percentage of hydrate cross-sectional area, through the establishment of exhaust gas pipe network model and mathematical model, we analyzed how the various factors (temperature, pressure, ground temperature, throughput) influenced the frozen blocking of pipe networks, and the results showed that the cross-sectional area percentage of 37.6% is frozen blocking break points, and the input’s effect on the frozen blocking is the largest. The error in this mathematical model between the prediction of frozen blocking position and actual position is within the scope of the permit (5%). So it can guide the production work in the winter, to reduce the loss of oil field, and increase the economic benefit.Key words: Fire flooding exhaust; Frozen blocking; Mathematical model; Frozen blocking predictio

A New Transcatheter Aortic Valve Replacement System for Predominant Aortic Regurgitation Implantation of the J-Valve and Early Outcome

AbstractObjectivesThis study introduces a newly designed transcatheter aortic valve system, the J-Valve system, and evaluates its application in patients with predominant aortic regurgitation without significant valve calcification. We also report the early results of one of the first series of transapical implantations of this device and aim to offer guidance on the technical aspects of the procedure.BackgroundTranscatheter aortic valve replacement (TAVR) has been widely used in high-risk patients for surgical aortic valve replacement. However, the majority of the TAVR devices were designed for aortic valve stenosis with significant valve calcification.MethodsSix patients with native aortic regurgitation without significant valve calcification (age, 61 to 83 years; mean age, 75.50 ± 8.14 years) underwent transapical implantation of the J-Valve prosthesis (JieCheng Medical Technology Co., Ltd., Suzhou, China), a self-expandable porcine valve, in the aortic position at our institution. All patients were considered to be prohibitive or high risk for surgical valve replacement (logistic EuroSCORE [European System for Cardiac Operative Risk Evaluation], 22.15% to 44.44%; mean, 29.32 ± 7.70%) after evaluation by an interdisciplinary heart team. Procedural and clinical outcomes were analyzed.ResultsImplantations were successful in all patients. During the follow-up period (from 31 days to 186 days, mean follow-up was 110.00 ± 77.944 days), only 1 patient had trivial prosthetic valve regurgitation, and none of these patients had paravalvular leak of more than mild grade. There were no major post-operative complications or mortality during the follow-up.ConclusionsOur study demonstrated the feasibility of transapical implantation of the J-Valve system in high-risk patients with predominant aortic regurgitation

First identification of long non-coding RNAs in fungal parasite Nosema ceranae

International audienceAbstractNosema ceranae is a unicellular fungal parasite of honey bees and causes huge losses for apiculture. Until present, no study on N. ceranae long non-coding RNAs (lncRNAs) was documented. Here, we sequenced purified spores of N. ceranae using strand-specific library construction and high-throughput RNA sequencing technologies. In total, 83 novel lncRNAs were predicted from N. ceranae spore samples, including lncRNAs, long intergenic non-coding RNAs (lincRNAs), and sense lncRNAs. Moreover, these lncRNAs share similar characteristics with those identified in mammals and plants, such as shorter length and fewer exon number and transcript isoforms than protein-coding genes. Finally, the expression of 12 lncRNAs was confirmed with RT-PCR, confirming their true existence. To our knowledge, this is the first evidence of lncRNAs produced by a microsporidia species, offering novel insights into basic biology such as regulation of gene expression of this widespread taxonomic group

N2 fixation rate and diazotroph community structure in the western tropical North Pacific Ocean

Abstract(#br)In the present study, we report N2 fixation rate (15N isotope tracer assay) and the diazotroph community structure (using the molecular method) in the western tropical North Pacific Ocean (WTNP) (13°–20°N, 120°–160°E). Our independent evidence on the basis of both in situ N2 fixation activity and diazotroph community structure showed the dominance of unicellular N2 fixation over majority of the WTNP surface waters during the sampling periods. Moreover, a shift in the diazotrophic composition from unicellular cyanobacteria group B-dominated to Trichodesmium spp.-dominated toward the western boundary current (Kuroshio) was also observed in 2013. We hypothesize that nutrient availability may have played a major role in regulating the biogeography..