Résumé -Dérivation de l'équation d'énergie de l'écoulement huile-gaz dans des pipelines -Lors de la simulation d'un écoulement multiphasique huile-gaz dans une conduite, le calcul thermodynamique représente un processus important en interaction avec le calcul hydraulique ; il influence la convergence du programme et la précision des résultats. La forme de l'équation d'énergie constitue la clef du calcul thermodynamique. Basée sur l'équation d'énergie de l'écoulement huile-gaz dans un pipeline, la formule de chute de température explicite (ETDF ; Explicit Temperature Drop Formula) est dérivée pour un calcul de température d'état stable huile-gaz. Cette nouvelle équation d'énergie prend en compte de nombreux facteurs, tels que l'effet Joule-Thomson, le travail de pression, le travail de frottement, ainsi que l'incidence des ondulations de terrain et le transfert de chaleur avec le milieu extérieur le long de la ligne. Ainsi, il s'agit d'une forme globale de l'équation d'énergie, laquelle pourrait décrire précisément la réalité d'un pipeline à phases multiples. Pour cette raison, un certain nombre de points de vue de la littérature à propos du calcul de température d'un écoulement diphasique huile-gaz dans des pipelines sont passés en revue. L'élimination de la boucle d'itération de température et l'intégration de l'équation de température explicite, au lieu de l'équation d'énergie d'enthalpie, dans le calcul conjugué hydraulique et thermique, se sont avérées améliorer l'efficacité de l'algorithme. Le calcul a été appliqué non seulement au modèle de composants mais aussi au modèle Black-Oil. Ce modèle est incorporé respectivement dans le modèle de composants ainsi que le modèle Black-Oil et deux simulations sont effectuées sur deux pipelines en service, les pipelines multiphasiques Yingmai-Yaha et Lufeng ; les résultats de température sont comparés à la simulation calculée par OLGA et aux résultats mesurés. Il est montré que ce modèle a très bien simulé la distribution de températures. Enfin, on a analysé l'influence de la capacité thermique spécifique du pétrole et du gaz sur la température du mélange des fluides et l'influence de l'effet Joule-Thomson sur la répartition de température sur le pipeline. Il est montré que le coefficient de Joule-Thomson représente un facteur clef pour décrire correctement un écoulement diphasique huile-gaz. Oil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 68 (2013), No. 2, pp. 341-353 Copyright © 2012, IFP Energies nouvelles DOI: 10.2516/ogst/2012020 Oil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 68 (2013 Abstract -Energy Equation Derivation of the Oil-Gas Flow in Pipelines -In the simulation of oil-gas pipeline multiphase flow, thermodynamic computation is an important process interacting with the hydraulic calculation and it influences the convergence of the program and the accuracy of the results. The form of the energy equation is the key to the thermodynamic computation. Based on the energy equation of oil-gas flow in pipeline, the E...
A/chicken/Nanjing/908/2009(H11N2) (CK908) was isolated from a live poultry market in Nanjing, China. Using PCR and sequencing analysis, we obtained the complete genome sequences of the CK908 virus. The sequence analysis demonstrated that this H11N2 virus was a novel reassortant AIV whose PB1, PB2, PA, HA, NP, NA, M, and NS genes originated from H9N2, H7N7, H5N2, H11N8, H3N6, H6N2, H1N1, and H5N1, respectively. Knowledge regarding the complete genome sequences of the CK908 virus will be useful for epidemiological surveillance. Avian influenza virus (AIV) originates from birds, particularly wild waterfowl, and has been demonstrated to have 16 hemagglutinin (HA) and 9 neuraminidase (NA) subtypes (1, 3). In the early 1970s, live poultry markets (LPM) were considered to be a prolific source of AIVs (5). H11N2 subtype avian influenza virus can infect wild birds (1), turkey, and gull (3). In addition, serum surveillance demonstrated that Lebanese backyard poultry growers, who were frequently exposed to chicken, may have been infected with H11 avian influenza virus (4). This result indicated that H11 influenza virus may possess the ability to cross the species barrier to infect humans. Thus, it is important to enhance surveillance for H11 AIVs.In this study, A/chicken/Nanjing/908/2009(H11N2) (CK908) was isolated from LPM in Nanjing, China. The PCR was performed using universal primers for influenza A virus (2). The amplification products were directly sequenced, and the SEQMAN program (DNASTAR, Madison, WI) was used to analyze the sequences.The genome of the CK908 virus consisted of 8 segments of single-stranded RNA and was 13,623 nucleotides in length. The polymerase genes PB1 and PB2 each consisted of 2,341 nucleotides; the polymerase acidic (PA) gene consisted of 2,233 nucleotides; the HA gene, 1,760 nucleotides; the nucleoprotein (NP) gene, 1,565 nucleotides; the NA gene, 1,466 nucleotides; the matrix (M) gene, 1,027 nucleotides; and the nonstructural (NS) gene, 890 nucleotides.Sequence analysis revealed that the nucleotide sequences of the HA gene of the CK908 virus were most closely related to that of the H11N8 isolate A/mallard/Netherlands/17/2007(H11N8) and shared 98% nucleotide homology. The NA fragment was most closely related to H6N2 isolate A/mallard/Jiangxi/8264/2004 (H6N2) and shared 98% nucleotide homology with it. The nucleotide sequences of PB1 and PB2 genes were most closely related to those of the H9N2 isolate A/avian/Egypt/920431/2006(H9N2) and the H7N7 isolate A/shoveler/Italy/2698-3/2006(H7N7), with which they shared 97% and 98% nucleotide homology, respectively. The nucleotide sequences of the PA gene were most closely related to that of the H5N2 isolate A/wild bird/Korea/A81/ 2009(H5N2) and shared 99% nucleotide homology with it. The nucleotide sequences of the NP and M genes were most closely related to those of the H3N6 isolate A/red crested pochard/ Mongolia/1915Mongolia/ /2006 and H1N1 isolate A/duck/Eastern China/103/2003(H1N1), with which they shared 98% and 95% nucleotide homology, respect...
Aimed at problems of poor fracturing effects of fracture-network acid fracturing in three wells in the Keshen 5 block, a fractured and tight gas reservoir in Tarim Oilfield, the mechanical activity of natural fractures was studied. The fractures in this block were divided into three types: fully-filled, semi-filled, and unfilled. The analysis of the correlations showed that the correlation of the number of fully-filled fractures and absolute open flows (AOF) is poor, while the correlation between the number of unfilled and semi-filled fractures and AOF is the best. Core samples with different types of fractures were tested using conventional triaxial compression methods, and the experimental results showed that the friction coefficient of the fully-filled fracture is close to that of semi-filled fracture, while the cohesion of fully-filled natural fractures is close to that of intact rocks, which is much greater than that of semi-filled fractures. The effective stress test results shows that the effective stress coefficient of fully-filled natural fracture rock samples is lower than that of semi-filled fractures. Using Mohr–Coulomb theory to calculate the natural fracture mechanics of high-production wells and low-production wells, the results show that low-production wells are mainly fully-filled fractures, most of which are not activated, so the production is low; while high-production wells are semi-filled and unfilled fractures, most of which can be activated, so the production is high. Based on this, for a well dominated by fully-filled fractures, it is recommended to use conventional gel fracturing to replace the fracture-network acid fracturing process. The stimulation practice of two wells has proven the validity of this strategy. The filling degree of natural fractures affects the increasing production and choice of stimulation process. This may be a relatively new understanding and may provide insights to stimulation strategy decisions for other fractured tight reservoirs in the world.
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