Investigation of alkaline–crude oil reaction

AbstractOne of the mechanisms of alkaline flooding relies on alkaline reaction with organic acids (saponifiable components) in the crude oil to produce an in situ surfactant called soap that lowers interfacial tensions. However, this mechanism is not quantified in the literature. For example, what is the fraction of acid components which react with alkaline solution to generate soap? How much soap can be generated?In this paper, this mechanism and related issues are discussed, analyzed or quantified. In particular, the numerical simulation approach is used. The results show that only a fraction of acid components can be converted into soap; the amount of generated soap could be low. A minimum pH (e.g. 9) is needed for the acids to be converted to soap. The literature information on the effect of amount of acid components (total acid number) on oil recovery is also discussed

Review of Surfactant Enhanced Oil Recovery in Carbonate Reservoirs

About half of proven conventional oil reserves are in carbonate reservoirs. Due to complex structures, formation heterogeneities and oil-wet/mixed wet conditions, etc., the oil recovery factor in carbonate reservoirs is very low. There is increasing interest in improve oil recovery using surfactants, as the surfactant EOR has the potential after other EOR methods have been tried.This paper reviews the models of wettability alteration using surfactants and upscaling models related to oil recovery in carbonate reservoirs. Chemicals used in carbonate reservoirs are reviewed. The field cases where surfactants were used to stimulate oil recovery are analyzed.Key words: Enhanced oil recovery; Carbonate reservoirs; Wettability alteration; Chemical EO

A Comparative Experimental Study of Sweep Efficiency in Naturally Fractured Reservoirs

In this paper the performance of gel and polymer in fractured core plugs in laboratory is compared. The experimental results show that in a naturally fractured reservoir, the best solution to improve oil recovery should be such that the gel particle sizes are larger than the pore sizes, and the solution viscosity becomes very high after the particles contact with water. If the fracture is wide, the improvement of sweep efficiency by a polymer solution is limited because the polymer solution could flow through the fracture channel. The results in this paper provide us with guidelines to select proper polymers to improve sweep efficiency.Key words: Sweep efficiency; Naturally fractured reservoirs; Polymer solution; Oil recover

Analyze Horizontal Well Tests Using Reservoir Simulation Approach–a Case Study

Analysis based on analytical solutions dominates in conventional well testing analysis. Analytical solutions, however, meet their challenges under some complex test conditions. This paper presents a case study of horizontal well testing analysis using simulation approach. In this case study, we show an example that the horizontal well tests, sometimes, could not be analyzed using conventional well testing methods, but they could be analyzed using simulation approach (a single well model in this case). By history matching the well tests, we calibrated the single well model. Then using the calibrated model, we analyzed the actual well performance. We also used the single well model to design a new drawdown test. The new drawdown test was successfully conducted and analyzed using an analytical model. The analysis results are consistent with those obtained from the earlier tests analyzed using simulation approach.Key words: Reservoir simulation approach; Horizontal well; ECLIPSE; PanSyste

Reactive oxygen species drive herpes simplex virus (HSV)-1-induced proinflammatory cytokine production by murine microglia

Abstract Background Production of reactive oxygen species (ROS) and proinflammatory cytokines by microglial cells in response to viral brain infection contributes to both pathogen clearance and neuronal damage. In the present study, we examined the effect of herpes simplex virus (HSV)-1-induced, NADPH oxidase-derived ROS in activating mitogen-activated protein kinases (MAPKs) as well as driving cytokine and chemokine expression in primary murine microglia. Methods Oxidation of 2', 7'-dichlorodihydrofluorescin diacetate (H2DCFDA) was used to measure production of intracellular ROS in microglial cell cultures following viral infection. Virus-induced cytokine and chemokine mRNA and protein levels were assessed using real-time RT-PCR and ELISA, respectively. Virus-induced phosphorylation of microglial p38 and p44/42 (ERK1/2) MAPKs was visualized using Western Blot, and levels of phospho-p38 were quantified using Fast Activated Cell-based ELISA (FACE assay). Diphenyleneiodonium (DPI) and apocynin (APO), inhibitors of NADPH oxidases, were used to investigate the role of virus-induced ROS in MAPK activation and cytokine, as well as chemokine, production. Results Levels of intracellular ROS were found to be highly elevated in primary murine microglial cells following infection with HSV and the majority of this virus-induced ROS was blocked following DPI and APO treatment. Correspondingly, inhibition of NADPH oxidase also decreased virus-induced proinflammatory cytokine and chemokine production. In addition, microglial p38 and p44/42 MAPKs were found to be phosphorylated in response to viral infection and this activation was also blocked by inhibitors of NADPH oxidase. Finally, inhibition of either of these ROS-induced signaling pathways suppressed cytokine (TNF-α and IL-1β) production, while chemokine (CCL2 and CXCL10) induction pathways were sensitive to inhibition of p38, but not ERK1/2 MAPK. Conclusions Data presented herein demonstrate that HSV infection induces proinflammatory responses in microglia through NADPH oxidase-dependent ROS and the activation of MAPKs.</p

A self-similar analytical solution of spontaneous and forced imbibition in porous media

Both viscous and capillary forces control the two-phase flow in porous media. The Buckley Leverett solution for viscous flow in porous media has been proposed for over a half century. While the corresponding studies of capillary dominated solutions are mainly based on the capillary tube based models. The continuum solutions are just prevail in recently years. The analytical solution of the combination of both effects is rarely investigated. A self-similar analytical solution of spontaneous and forced imbibition in porous media is proposed in this work and the corresponding concise algorithms are presented. The proposed solution successfully solves this typical non-linear partial differential equation by introducing a transformation variable and the capillary fractional flow function analog to the fractional flow function of Buckley Leverett solution. Finally, the case study is performed, which demonstrates the feasibility and accuracy of this proposed solution to a general two-phase flow condition.Cited as: Wang, X., Sheng, J.J. A self-similar analytical solution of spontaneous and forced imbibition in porous media. Advances in Geo-Energy Research, 2018, 2(3): 260-268, doi: 10.26804/ager.2018.03.0

Gene functional similarity search tool (GFSST)

BACKGROUND: With the completion of the genome sequences of human, mouse, and other species and the advent of high throughput functional genomic research technologies such as biomicroarray chips, more and more genes and their products have been discovered and their functions have begun to be understood. Increasing amounts of data about genes, gene products and their functions have been stored in databases. To facilitate selection of candidate genes for gene-disease research, genetic association studies, biomarker and drug target selection, and animal models of human diseases, it is essential to have search engines that can retrieve genes by their functions from proteome databases. In recent years, the development of Gene Ontology (GO) has established structured, controlled vocabularies describing gene functions, which makes it possible to develop novel tools to search genes by functional similarity. RESULTS: By using a statistical model to measure the functional similarity of genes based on the Gene Ontology directed acyclic graph, we developed a novel Gene Functional Similarity Search Tool (GFSST) to identify genes with related functions from annotated proteome databases. This search engine lets users design their search targets by gene functions. CONCLUSION: An implementation of GFSST which works on the UniProt (Universal Protein Resource) for the human and mouse proteomes is available at GFSST Web Server. GFSST provides functions not only for similar gene retrieval but also for gene search by one or more GO terms. This represents a powerful new approach for selecting similar genes and gene products from proteome databases according to their functions

Purge–Mainstream Interactions in a Turbine Stage With Rotor Endwall Contouring

Purge flows are prevalent in modern gas turbine design, allowing for increased turbine entry temperatures. The purge flow passes through a rim seal and interacts with the mainstream flow, modifying the blade secondary flow structures and reducing stage efficiency. These structures may be controlled using end wall contouring (EWC), though experimental demonstration of their benefit is seldom reported in the literature. The optically accessible turbine at the University of Bath was designed to directly measure and visualize the flow field within the blade passage for a rotor with EWC. The single-stage turbine enables phase-locked flow field measurements with volumetric particle image velocimetry (PIV). Purge flow was supplied to investigate a range of operating conditions in which the secondary flow structures were modified. The modular turbine rotor allowed for expedient change of a bladed ring, or bling, featuring non-axisymmetric EWC. The identified secondary flow structures were the pressure-side leg of the horse shoe vortex (PS-HSV) and an egress vortex (EV) of concurrent rotational direction. An increase in purge flowrate monotonically shifted the EV toward the suction-side (SS) of the adjacent blade. The migration of the PS-HSV toward the SS caused the two aforementioned vortices to merge. The EWC rotor design included a leading-edge (LE) feature to alter the PS-HSV and a trough to guide the EV low spanwise in the passage and maintain displacement from the adjacent suction-side. The EWC rotor was found to be effective at altering the formation and positioning of the secondary flow structures at a range of purge flow conditions

Reynolds number influences in aeronautics

Reynolds number, a measure of the ratio of inertia to viscous forces, is a fundamental similarity parameter for fluid flows and therefore, would be expected to have a major influence in aerodynamics and aeronautics. Reynolds number influences are generally large, but monatomic, for attached laminar (continuum) flow; however, laminar flows are easily separated, inducing even stronger, non-monatomic, Reynolds number sensitivities. Probably the strongest Reynolds number influences occur in connection with transitional flow behavior. Transition can take place over a tremendous Reynolds number range, from the order of 20 x 10(exp 3) for 2-D free shear layers up to the order of 100 x 10(exp 6) for hypersonic boundary layers. This variability in transition behavior is especially important for complex configurations where various vehicle and flow field elements can undergo transition at various Reynolds numbers, causing often surprising changes in aerodynamics characteristics over wide ranges in Reynolds number. This is further compounded by the vast parameterization associated with transition, in that any parameter which influences mean viscous flow development (e.g., pressure gradient, flow curvature, wall temperature, Mach number, sweep, roughness, flow chemistry, shock interactions, etc.), and incident disturbance fields (acoustics, vorticity, particulates, temperature spottiness, even electro static discharges) can alter transition locations to first order. The usual method of dealing with the transition problem is to trip the flow in the generally lower Reynolds number wind tunnel to simulate the flight turbulent behavior. However, this is not wholly satisfactory as it results in incorrectly scaled viscous region thicknesses and cannot be utilized at all for applications such as turbine blades and helicopter rotors, nacelles, leading edge and nose regions, and High Altitude Long Endurance and hypersonic airbreathers where the transitional flow is an innately critical portion of the problem