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Acidic gas penetration through the internal pressure sheath of a flexible riser tends to cause a corrosive environment in the annulus, reducing the service life of the flexible riser. Nanoparticles can act as gas barriers in the polymer matrix to slow down the gas permeation. Herein, we prepared PA11/SiO2 composites by the melt blending method. The effect of adding different amounts of SiO2 to PA11 on its gas barrier properties was investigated by conducting CO2 permeation tests between 20 °C and 90 °C. As the temperature increased, the lowest value of the permeability coefficient that could be achieved for the PA11 with different contents of SiO2 increased. The composites PA/0.5% SiO2 and PA/1.5% SiO2 had the lowest permeation coefficients in the glassy state (20 °C) and rubbery state (≥50 °C). We believe that this easy-to-produce industrial PA/SiO2 composite can be used to develop high-performance flexible riser barrier layers. It is crucial for understanding riser permeation behavior and enhancing barrier qualities.

Acidic gas penetration through the internal pressure sheath of a flexible riser tends to cause a corrosive environment in the annulus, reducing the service life of the flexible riser. Nanoparticles can act as gas barriers in the polymer matrix to slow down the gas permeation. Herein, we prepared PA11/SiO

The flexible composite pipes are quite suitable for the development of marine oil&gas reservoirs due to the excellent characteristics of design abilities, economics and dynamic behaviors. At present, the theories and methods of the gas permeations in the composite walls have not yet considered the influences of the multiphase flow in the inner pipes. Therefore, the prediction accuracies of the permeation rates are expected to improve for the marine flexible pipelines with significant differences of pressure and temperature drops. In this paper, a comprehensive gas permeation model including gas-liquid two-phase flow is proposed, and the effect of flow patterns on the gas permeation rate and vent period is investigated numerically. The results show that the flow patterns of multi-phase flow have significant impact on the permeation rate of gas due to different pressure drop and temperature drop for the same mass flow rate, and the permeation rate of CO2 is higher than that of CH4 under the same working condition.

Flexible risers are widely employed in deep-sea oil and gas development. Methane, carbon dioxide, water vapor, and other small molecular gases can permeate into the sheaths and accumulate with water condensation in the annulus, which may cause overpressure and corrosion accidents. A mechanistic model was proposed to describe the permeation of gas phase in the multiphase flow though the flexible riser inner surface and its condensation in the internal annular space. The governing equations were solved efficiently by a combination of the control volume method and the finite difference method. After validation of the models, the thermo-hydraulic characteristics, concentration fields, annulus conditions, flow patterns, and some key parameters were comprehensively investigated. The results showed that with increasing the inlet pressure and temperature, the initiation time of venting and its duration decreased exponentially. The venting frequency can be adjusted by selecting an appropriate shielding factor and venting pressure. When the shielding factor is larger than 0.75 or the venting pressure is greater than 500 kPa, the venting cycle will be significantly prolonged. The gas permeation rates varied in a wide range of 2 times with flow patterns.

In this study, a small-scale natural gas liquefaction device was built to verify the feasibility of optimization results of the dual nitrogen expansion natural gas liquefaction process with pre-cooling. From the thermodynamics perspective, the feasibility of using R22 instead of propane as a pre-cooling refrigerant, and nitrogen instead of natural gas as the feed gas was verified. Furthermore, a genetic algorithm was used to optimize the operational parameters of the dual nitrogen expansion liquefaction process. The operational performance and adaptability of the process were evaluated based on sensitivity experiments. The experimental results revealed that the relative error of the key node parameters between the experimental and simulation results was within 10%. Moreover, the experimental device and liquefaction process had a relatively large processing capacity (approximately between 35% and 130%), which is suitable when gas field production attenuation is relatively fast. The experimental device was insensitive to the pressure and temperature of the feed gas, and exhibited excellent adaptability.

In the field of LNG simulation study, most optimization studies have concentrated on the LNG processes at steady-state simulation, and only a few studies have reported the dynamic simulation of the LNG process, which is closer to actual operating conditions. The main purpose of this study was to design a dynamic model of propane pre-cooling double nitrogen-expander LNG process based on an actual LNG plant, to investigate the dynamic behavior of this process, which had been considered suitable for FLNG process in previous studies. Furthermore, this is one of the first studies to verify the dynamic simulation of this process through the actual operation of an LNG plant. First, the dynamic models of the main equipment used in this process were developed. Second, a dynamic simulation of this process was performed, and the dynamic behaviour was investigated. Finally, to verify the accuracy of the dynamic simulation, different types of dynamic conditions were added to the simulation to investigate the behaviour of the process, including disturbances in the feed gas flow rate and shutting down of the propane system. Further, the dynamic responses and average errors between the experimental and simulated values were obtained and discussed. The results indicated that the two-stream heat exchange model can be used to replace the multi-stream heat exchange model for dynamic simulation, with the average error of dynamic simulation being under 10%, the control system can resolve the problem of excess cooling capacity and make the entire system run stably in the case of feed gas flow rate disturbance, the whole system returns to stability within 100 min in the case of the propane system shutdown. The results can provide feasible prediction and verification methods for the construction of large experimental and liquefaction production devices in the future.

Crude oils are generally very complex chemical systems consisting predominantly of hundreds to thousands of hydrocarbon compounds from simple low-molecular-weight paraffin to high-molecular-weight waxes. There are many factors effecting wax deposition such as the fluid composition, pressure and temperature and so on. Wax deposition is complex dynamic process related to transient heat and mass transfer, therefore it is very difficult to predict wax deposition velocity accumulation amounts on the wall in waxy crude oil tieback flowlines. There exist many waxy crude oil tieback flowlines for South China Sea deepwater oil development, which can cause many flow assurance problems. It is very important to carry out wax deposition prediction calculation and effective measures are adopted to solve flow assurance problems. In this study, based on certain waxy crude oil tieback flowlines for South China Sea deepwater oil development, OLGA software is used to simulate transient flow characteristics in waxy crude oil tieback flowlines such as wax precipitation rate, thickness of wax layer deposited at wall, pigging frequency and so on. OLGA software simulation results is coincident with field pigging operation results, finally obtaining a good simulation methods to predict transient flow characteristics in waxy crude oil tieback flowlines and giving good suggestions to determine pigging periods and frequency. The study results show two 10 inch non-insulation steel flowlines are recommended to develop deepwater waxy crude oil field and pigging periods should comprehensive consider thickness of wax layer deposited at wall and the increase of pressure caused by wax deposition. It is reasonable to 35 days pigging periods during 2 year after put into production, 60 days pigging periods after 2 years. The results show maximum liquid flow rate for a 10 inch flowline is 7000m3/d, and it is reasonable that one flowline is used to transport when flow rate is lower than 7000m3/d, and two flowlines are used to transport when flow rate is more than 7000m3/d. The pump pressure at FPSO is kept at 6000kPaA, and required maximum liquid flow rate of pigging at FPSO is 4200m3/d (175m3/h).

The mal-distribution of gas and liquid is the critical issue that can lead to the heat transfer deterioration in plate-fin heat exchangers, especially when the sloshing exists for the floating liquefied natural gas system. The severe sloshing motions of the sea strongly influence the uniformity of the gas–liquid distribution in heat exchangers. In this paper, a new entrance configuration is proposed to allow the distributor to provide a uniform two-phase flow before the two different fluids were mixed. As a comparison, both the uniformity and sloshing resistance are analyzed on gas–liquid distribution performances for the conventional header and the present proposed structure. Both the steady-state and the sloshing motion conditions are numerically simulated by using a CFD software FLUENT. The results show that the effectiveness of the proposed gas–liquid distributors was confirmed and the new design can significantly improve the uniformity of the gas–liquid distribution and the sloshing resistance of heat exchangers.

The study of formation and dissociation of CO2 hydrate in porous media was characterized by magnetic resonance imaging (MRI) system in in situ conditions. This work simulated porous media by using glass beads of uniform size. The growth and dissociation habit of CO2 hydrate was observed under different temperature and pressure conditions. The induction time and the hydrate saturation during the growth and dissociation process in different sizes of porous media were obtained by using the MRI signal intensity. The results indicate that hydrate growth rate and the induction time are affected by the size of porous media, pressure, and degree of supercooling. There are three hydrate growth stages, i.e., initial growth stage, rapid growth stage and steady stage. In this study, the CO2 hydrate forms preferentially at the surface of vessel and then gradually grows inward. The hydrate tends to cement the glass beads together and occupies the pore gradually. As the hydrate decomposes gradually, the dissociation rate increases to the maximum and then decreases to zero.

Liquefaction process is one of the key technologies of offshore FLNG device and is charged by a few of the company’s patent protection. Due to the special offshore operating environment, the choice of FLNG liquefaction process is different from that of onshore. It is very important that FLNG liquefaction process suitable for the marine environment and the oil and gas properties of the South China Sea. In this paper, the static and dynamic performance of propane pre-cooling and dual nitrogen expansion liquefaction process with independent intellectual property rights have been verified by experiment loop simulation with small scale 2000m3/d and middle scale 20000m3/d. Dynamic simulation experimental measures for liquefying key devices such as cold box placed on the swing experiment platform and propane separation tank and the cold box between difference of liquid level changes, are used to verify offshore adaptability of the liquefaction process. Through the static experiments of a small experimental loop with the scale of 2000m3/d simulation considers the liquefaction rate of 93%, energy consumption 0.42kw.h/m3; Dynamic experimental results through the cold box placed on the swinging platform shows that the heat transfer performance of cold box is not affected when FLNG hull roll wave reached 3.6 degrees. The mid-scale experimental simulation of 20000m3/d show that the liquefaction process has the advantages of simple debugging process, convenient operation, quick shutdown and restart, flexible operation, good adaptability to offshore operating parameters, and can realize 3 sets of refrigeration cycles simulation. The propane pre-cooling and dual nitrogen expansion liquefaction process with independent intellectual property rights through the static and dynamic experiments of small and middle scale experimental loop, is verified to the characteristics of high liquefaction rate, low energy consumption and good offshore adaptability. The liquefaction process with independent intellectual property rights can be used to as one of FLNG facility key technologies to develop offshore gas field and faraway from onshore of the South China Sea.

Diabetes is known to exacerbate cerebral ischemia/reperfusion (I/R) injury. Here, we investigated the effects of Clostridium butyricum on cerebral I/R injury in the diabetic mice subjected to 30min of bilateral common carotid arteries occlusion (BCCAO). The cognitive impairment, the blood glucose level, neuronal injury, apoptosis, and expressions of Akt, phospho-Akt (p-Akt), and caspase-3 level were assessed. Meanwhile, the changes of gut microbiota in composition and diversity in the colonic feces were evaluated. Our results showed that diabetic mice subjected to BCCAO exhibited worsened cognitive impairment, cell damage and apoptosis. These were all attenuated by C. butyricum. Moreover, C. butyricum reversed cerebral I/R induced decreases in p-Akt expression and increases in caspase-3 expression, leading to inhibiting neuronal apoptosis. C. butyricum partly restored cerebral I/R induced decreases of fecal microbiota diversity, changes of fecal microbiota composition. Together, these findings highlight the important role of bacteria in the bidirectional communication of the gut-brain axis and suggest that certain probiotics might prove to be useful therapeutic adjuncts in cerebral I/R injury with diabetes.

Gas hydrate decomposition in sediments involves complicated multiphase flow and heat and mass transfer processes because of heat absorption by solid hydrates. Factors affecting gas hydrate decomposition in sediments include sediment type, mineral composition, pore size distribution, particle size, pore water composition, hydrate saturation distribution, initial formation pressure and temperature and cement characteristics. In this paper, experimental simulations of gas hydrate decomposition are carried out on an artificial core to investigate the effects of initial pressure and temperature, particle size and pore size. The experiments show that the characteristics of gas hydrate decomposition in sediments differ completely from those in a pure water system. The decomposition rate of hydrate sediments increases with the initial pressure increasing and decreasing temperatures. Furthermore, the decomposition rate of hydrate sediments decreases with decreasing particle size and increasing pore size.

The influences of halogen ions extracted from sodium fluoride, sodium chloride, sodium bromide, and sodium iodide and their concentrations on methane hydrate phase equilibrium conditions in porous media were investigated experimentally using an orthogonal test method at a pressure of 8 MPa. The experimental results showed that the equilibrium temperature of methane hydrate decreased when halogen ions were added. The equilibrium temperature decreased with the increase of halogen ion concentrations. The influence of the sources of the halogens ion to the methane hydrate equilibrium temperature were insensitive according to variance analysis, which could be explained by about the same mean ionic activity coefficient (a dimensionless coefficient relates the activity to a measured concentration) of sodium fluoride, sodium chloride, sodium bromide, and sodium iodide. The experimental measurements were also in close agreement with the thermodynamic model of Song et al. (J. Nat. Gas Chem. 19, 241 (2010)), in which the mechanical equilibrium of force between the interfaces in a hydrate–liquid–vapor system was considered.

This paper introduces the research advances on replacement of CH4 in Natural Gas Hydrates (NGHs) by use of CO2 and discusses the advantages and disadvantages of the method on the natural gas production from such hydrates. Firstly, the feasibility of replacement is proven from the points of view of kinetics and thermodynamics, and confirmed by experiments. Then, the latest progress in CH4 replacement experiments with gaseous CO2, liquid CO2 and CO2 emulsion are presented Moreover, the superiority of CO2 emulsion for replacement of CH4 is emphasized. The latest experiment progress on preparation of CO2 emulsions are introduced. Finally, the advancements in simulation research on replacement is introduced, and the deficiencies of the simulations are pointed. The factors influencing on the replacement with different forms of CO2 are analyzed and the optimum conditions for the replacement of CH4 in hydrated with different forms of CO2 is suggested.

This paper introduces the research advances on replacement of CH 4 in Natural Gas Hydrates (NGHs) by use of CO 2 and discusses the advantages and disadvantages of the method on the natural gas production from such hydrates. Firstly, the feasibility of replacement is proven from the points of view of kinetics and thermodynamics, and confirmed by experiments. Then, the latest progress in CH 4 replacement experiments with gaseous CO 2 , liquid CO 2 and CO 2 emulsion are presented Moreover, the superiority of CO 2 emulsion for replacement of CH 4 is emphasized. The latest experiment progress on preparation of CO 2 emulsions are introduced. Finally, the advancements in simulation research on replacement is introduced, and the deficiencies of the simulations are pointed. The factors influencing on the replacement with different forms of CO 2 are analyzed and the optimum conditions for the replacement of CH 4 in hydrated with different forms of CO 2 is suggested.

Probiotics actively participate in neuropsychiatric disorders. However, the role of gut microbiota in brain disorders and vascular dementia (VaD) remains unclear. We used a mouse model of VaD induced by a permanent right unilateral common carotid arteries occlusion (rUCCAO) to investigate the neuroprotective effects and possible underlying mechanisms ofClostridium butyricum. Following rUCCAO,C. butyricumwas intragastrically administered for 6 successive weeks. Cognitive function was estimated. Morphological examination was performed by electron microscopy and hematoxylin-eosin (H&E) staining. The BDNF-PI3K/Akt pathway-related proteins were assessed by western blot and immunohistochemistry. The diversity of gut microbiota and the levels of butyrate in the feces and the brains were determined. The results showed thatC. butyricumsignificantly attenuated the cognitive dysfunction and histopathological changes in VaD mice.C. butyricumnot only increased the levels of BDNF and Bcl-2 and decreased level of Bax but also induced Akt phosphorylation (p-Akt) and ultimately reduced neuronal apoptosis. Moreover,C. butyricumcould regulate the gut microbiota and restore the butyrate content in the feces and the brains. These results suggest thatC. butyricummight be effective in the treatment of VaD by regulating the gut-brain axis and that it can be considered a new therapeutic strategy against VaD.

As one of the most promising equipment for deep far sea gas field development, FLNG has been widespread concern in the engineering sector. Due to the characteristic of LNG, the sloshing of liquid tank in FLNG is inevitable. Therefore, the sloshing load of liquid tank is one of the hotspots in engineering and academic research. In this paper, in order to simulate the sloshing load of liquid tank in FLNG, a secondary development software is proposed based on the commercial software FLUENT. The simulation results agree well with previous experimental results. This shows the accuracy of the simulation of the software. In addition, the longitudinal and transverse section of LNG tank is analyzed. The results shows that different excitation frequencies and amplitudes great influence on the sloshing load of liquid tanks, different filling levels also have a certain influence. This will be used to estimate the size of sloshing load for the FLNG equipment which may encounter in the real sea condition, and have certain significance in practical engineering.Copyright © 2014 by ASME

The decomposition process of gas hydrate in sediments is actually the dynamic phase transition process of solid hydrate in sediments after absorbing heat decomposition. According to the phase equilibrium characteristics of gas hydrate, there are three basic development methods, including heating, chemical injecting and depressurization. Currently, there is no good commercial software used to simulate heat transmission and mass transfer in the gas hydrate decomposition process. So in this paper, based on typical gas hydrate sediment in South China Sea, microcosmic, mesocosmic (fractal theory) and macrocosmic scales are respectively used to successfully reveal the heat and mass transfer mechanism of three basis development methods. Molecular dynamics simulation shows heat injection is the best method for heat and mass transferring, and chemical injecting is better than depressurization. Fractal theory is successfully used to describe the complex structure of the porous sediments with gas hydrate occurrence, and can realize the prediction of heat and mass transfer law of hydrate dissociation in porous media. Macrocosmic numerical simulation of depressurization for gas hydrate sediment in South China Sea shows gas hydrate reservoir geological model has a large influence on the gas hydrate decomposition, and permeability and hydrate saturation of the upper cover layer have great effect on gas hydrate decomposition. It is poor development efficiency for only depressurization development and the problem of water drainage should be paid attention during development process.Copyright © 2014 by ASME

As one aspect of flow assurance considerations, severe slugging control strategy in deepwater riser is related to the safety of production system, therefore it’s of great significance to the development of deepwater oil and gas field. This paper summarizes commonly used severe slugging control methods briefly, then takes certain deepwater oil and gas field as an example to introduce the method of software simulation for making severe slugging control strategy of deepwater riser. Firstly the model is built with basic information such as pipeline route, production profile and fluid composition. Data of typical years is used to simulate flowing conditions to determine whether it’s within slugging zone. To mitigate slugging conditions, choking, gas lift and choking& gas lift combined methods are chosen and simulated based on the oil and gas field characteristics, and according to the results gas lift is suggested as the best solution. Factors such as riser type, gas injection location, and flexible riser depth are analyzed for better gas lift efficiency. Finally hydrate formation risk related to severe slugging is analyzed and the slug catcher size is checked. Based on the introduced software simulation procedure, severe slugging control strategy is made, which will be valuable for deepwater flow assurance design and study.Copyright © 2014 by ASME

The current status of the FLNG research project is introduced in this paper. Primary focus is placed on the six key technical areas which have been addressed in the phase I of this project, i.e. liquefaction process, LNG tank sloshing, single point mooring system, LNG tank selection and arrangement, LNG offloading and FLNG risk assessment. Firstly, the selection and design of liquefaction process is presented. Based on the result of comparison with other liquefaction process, an optimized and patented propane pre-cooled nitrogen two-expander cycle process is proposed. Secondly, LNG tank sloshing is considered through numerical simulation and model test. Thirdly, single point mooring system is discussed and considered the impact of different ballast types of FLNG, Both internal turret and external turret are analyzed. Fourthly, a comparison of three commonly used types of LNG containment system is performed considering of both the system characteristics and technical competence in China. In addition, the arrangement of LNG tank is also considered in this paper. Fifthly, both side by side offloading and tandem offloading are discussed. It is pointed out that both types of offloading should be deeply studied in further for applicability for the specified environment condition in South China Sea. Finally, the FLNG risk assessment process and framework is established. Furthermore, a full scale quantitative risk analysis covering all the major hazards of FLNG will be studied in the phase II of the project. In addition to the six key technical areas, future works during phase II of this project in the next five years from 2011 are also proposed.

Extensive research focused on finding effective strategies to prevent or improve recovery from myocardial ischaemia/reperfusion (I/R) injury. Basic fibroblast growth factor (bFGF) has been shown to have therapeutic potential in some heart disorders, including ischaemic injury. In this study, we demonstrate that bFGF administration can inhibit the endoplasmic reticulum (ER) stress and mitochondrial dysfunction induced in the heart in a mouse model of I/R injury. In vitro, bFGF exerts a protective effect by inhibiting the ER stress response and mitochondrial dysfunction proteins that are induced by tert-Butyl hydroperoxide (TBHP) treatment. Both of these in vivo and in vitro effects are related to the activation of two downstream signalling pathways, PI3K/Akt and ERK1/2. Inhibition of these PI3K/Akt and ERK1/2 pathways by specific inhibitors, LY294002 and PD98059, partially reduces the protective effect of bFGF. Taken together, our results indicate that the cardioprotective role of bFGF involves the suppression of ER stress and mitochondrial dysfunction in ischaemic oxidative damage models and oxidative stress-induced H9C2 cell injury; furthermore, these effects underlie the activation of the PI3K/Akt and ERK1/2 signalling pathways.

According to the schematic and properties of a methane hydrate deposit in Shenhu Area of South China Sea in China, the characteristic of hydrate dissociation, water and gas production were simulated with a depressurization method. The effect of hydrate saturation, porosity and permeability et al. on hydrate dissociation was studied, the key controlling factor and difficulty of gas production from hydrate reservoir by depressurization was confirmed.Copyright © 2013 by ASME

Gas hydrates are crystalline solids that consist of gas molecules, usually methane, surrounded by water molecules. According to the phase equilibrium characteristics of gas hydrate, there are three basic development methods, including heating, pressure decreasing and chemical injecting. The development process is actually the multi-phase flow process. Currently, there is no good commercial software used to simulate the multiphase flow, heat transmission and mass transfer in the gas hydrate decomposition process. The study is not mature, still in the development and trial stage. So in this paper, we will make a deeply study on the multi-phase flow simulation method of gas hydrate decomposition in the sediment. We try to make breakthrough in the theory and simulate method. According to the different scales, the simulation computation study of flow characteristics model has microcosmic, mesocosmic and macrocosmic scales. In this paper, mesocosmic scales is used to study for the multiphase flow, heat and mass transfer in the offshore gas hydrate decomposition process, and numerical simulation and experimental simulation are together used to study. Study advancements are shown as follows: firstly, conventional Lattice Boltzmann model is modified to new Lattice Boltzmann Model (LBM) based on sediment with gas hydrate and flow characteristics for gas hydrate decomposition, the interaction and density difference between the phases are considered, and Magnetic Resonance Imaging (MRI) visual technology is used to successfully verified to LBM methods. Secondly, contraction core reaction methods based on fractal theory is used to simulate heat and mass transfer in the offshore gas hydrate decomposition process and is successfully verified by experimental simulation for South China Sea offshore gas hydrate sediment.Copyright © 2013 by ASME

In this paper, based on sediment with gas hydrate and flow characteristics for gas hydrate decomposition, the interaction and density difference between the phases are considered, conventional lattice Boltzmann model is modified to new lattice Boltzmann model then is applied to study flow characteristics for gas hydrate decomposition in sediment. The method is the mesoscopic model between macro and micro methods between. Modification lattice Boltzmann model is applied to carry out a complex micro-channel single-phase, multiphase flow simulation analysis, single-phase flow in porous media for gas hydrate decomposition. The results show that complex micro-channel flow field depends on the micro-channel roughness, bending degree, surface wet ability, fluid properties and other media. Single-phase flow in porous media depends on the pore diameter (saturation) and permeability of the sediment and the hydrate formation in the sediment so greatly reduces the permeability of porous media.Copyright © 2012 by ASME

LNG FPSO (LNG Floating Production Storage and Offloading Unit), is a new exploitation technology of offshore gas field. Acid gas removal process is the key link of pretreatment process which is foremost to FLNG technology, and directly affects the normal operation of subsequent processes. In this paper, based on the experience of onshore acid gas removal process technology, MDEA and DEA mixed amine solvent method has been used in acid gas removal process of offshore demonstration gas field. With the chemical simulation software HYSYS, the simulation analysis of acid gas removal process is completed and the effects of key parameters are analyzed. Finally, the recommended ranges of key parameters are given. The research results give some guidance and reference for the research of offshore floating acid gas removal process.

Multiphase flow and complex flow regimes of asphalt-base crude oil with solid-state asphalt and gas presenting in submarine pipelines bring difficulty to the design and operation. For multiphase flow in risers, flow regimes are often very complex. So simulation of asphalt-base crude oil flow in vertical riser is presented using 3D Computational Fluid Dynamics and the Volume of Fluid method as a surface tracking model. Flow regimes and properties of asphalt-base crude oil were obtained, which vary depending on operating conditions, fluid properties and flow rates. Bubble flow, slug flow, wave flow, annular flow and some other flow regimes could be found in vertical riser. Different flow regime does different impact on flow properties of asphalt-base crude oil and deposition of asphalt. A deeper understanding of multiphase flow phenomena in vertical riser was obtained by the calculation results, which also provide some reference to improve the design of pipelines and assurance transportation of asphalt-base crude oil.

Deposition of asphaltenes can occur in the tubing, pipelines and surface facilities leading to operational problems and loss in production. Nevertheless, accurate predictions of asphaltene instability have been elusive. Therefore, simulations of oil-gas-water three-phase flow in different structural pipelines are presented using 3D Computational Fluid Dynamics to get the distribution of each phase and the deposition rate of asphaltene. Calculation results show that flow velocity increases with the reduction of the effective cross-sectional area of the pipe, which leads to its vibration and shorter service life. In the other hand, pressure and temperature in the shrunken effective cross-sectional area decrease with the increase of velocity, intensifying the asphaltene deposition and transportation difficulty. Impact of deposition in bend and sudden changed pipelines is greater than that in straight ones. The calculation results of this paper can provide a guide for safe design and transportation of heavy crude oil in submarine pipelines.

To evaluate the effects of theanine on sedative effects induced by pentobarbital sodium.The locomotor activities of ICR mice induced by theanine (0.25, 0.5, 1.0, 2.0, 4.0 g x kg(-1)), pentobarbital sodium (5, 10 mg x kg(-1)) or the combination of both were determined with video-tracking system, and a novel index: Peripheral active time Peripheral time (PATP) was established. Hypnosis effect of combination of both was tested with right-reflex disappearance.Compared with normal saline (74.52 +/- 20.4)%, theanine alone decreased this PATP in dose-dependent manner from (62.03 +/- 21.11)%, (56.44 +/- 21.69)%, (31.13 +/- 17.2)%, (25.06 +/- 10.03)% to (17.21 +/- 7.43)% (P0.05, P0.05, P0.01, P0.01 and P0.01, respectively). Compared with pentobarbital sodium (5 mg x kg(-1)), between 0.25 g x kg(-1) and 1.0 g x kg(-1) theanine combined with that decreased peripheral PATP from (28.30 +/- 17.57)%, (30.64 +/- 17.21)% to (24.28 +/- 9.59)% (all P0.01), and increased by 2.0 g x kg(-1) reversely (61.95 +/- 19.39)%. Compared with normal saline, pentobarbital sodium (10 mg x kg(-1)) and the combination with theanine decreased significantly PATP (all P0.01). Compared with pentobarbital sodium (10 mg x kg(-1)), 0.25 g x kg(-1) theanine combined with that increased PATP [(25.37 +/- 13.68)% vs (10.08 +/- 7.98)%, P0.01)] and 0.5 g x kg(-1), 1.0 g x kg(-1) theanine could depresse that increase [(14.56 +/-10.10)%, (8.24 +/- 4.08)% vs (10.08 +/- 7.98)%]. Total distance and peripheral active time showed the same or similar tendency in theanine alone or combination with pentobarbital sodium . Theanine enchanced hypnosis effect of pentobarbital sodium in dose-dependent manner.Theanine can affect the sedative effect of low dose pentobarbital sodium in bidirectional action style but not change the hypnosis effect.

The transportation of heavy or waxy crude oils presents some special design problems, which must take into account the requirements for the control of asphaltene deposition on interior surfaces of the pipeline. With the asphaltene deposition of the crude oils, the effective cross-sectional area or flow passage of the pipeline will be shrunken continuously, which influences their flow properties and threatens their safe transportation. Therefore, the influence of asphaltene deposition on their flow properties should be known well to safely design and operate the pipeline. The focus in this paper is on the asphaltene deposition rate and the influence of the asphaltene deposition on flow properties. Simulations of heavy crude oil flow in different structural pipelines after various deposition patterns are presented using 3D CFD. The flow velocity of heavy crude oil increases with the reduction of the effective cross-sectional area of the pipe, which leads to its vibration and shorter service life. In the other hand, pressure and temperature in the shrunken effective cross-sectional area decrease with the increase of velocity, intensifying the asphaltene deposition and transportation difficulty. While flow properties vary depending on deposition patterns, flow rates and the pipe geometry. So the influence of asphaltene deposition on flow properties in different structural pipelines with various deposition patterns is diverse. The impact of deposition in bending and reducer pipelines is greater than that in straight ones. And the impact in serious deposition pipelines is greater than that in slight deposition ones. So flow properties change drastically in bending and reducer pipelines with serious asphaltene deposition, leading to rapid blockage of the pipelines. The results of this paper can provide a guide for safe design and transportation of heavy crude oil pipeline.