Effect of GTA on Gas Transporting SHS of Ti_5Si_3

By doping gas transport agents (GTA), the combustion process and structural formation of SHS can be significantly varied. In this paper, Ti5Sis was synthesized by SHS method using AICI3·6H2O as GTA. The effect of GTA was studied by measuring combustion process parameters. XRD and SEM were used to determine the phases and microstructures of products. The structural formation of 7V6Si3 with different GTA contents was studied by CFQ method. Three mechanisms were deduced.

Behavior of transporting pipeline sections without and with hydrogen exposure based on full-scale tests

Pipeline transport of hydrogen is one of today’s economic and environmental challenges.In order to find safe and reliable application of both existing gas and build new pipelines,it is essential to carry out tests on full-scale pipeline section,including the potentially more dangerous places than the main pipe,the girth welds.For the investigations,pipeline sections of P355NH steel with girth welds were prepared and exposed to pure hydrogen at twice the maximum allowable operating pressure for 41 days.Subsequently,full-scale burst tests were carried out and specimens were cut and prepared from the typical locations of the failed pipeline sections for mechanical,and macro-and microstructural investigations.The results obtained were evaluated and compared with data from previous full-scale tests on pipeline sections without hydrogen exposure.The results showed differences in the behavior of pipeline sections loaded in different ways,with different characteristics of the materials and the welded joints,both in the cases without hydrogen exposure and in the cases exposed to hydrogen.

A STAMP-Game model for accident analysis in oil and gas industry

Accidents in engineered systems are usually generated by complex socio-technical factors.It is beneficial to investigate the increasing complexity and coupling of these factors from the perspective of system safety.Based on system and control theories,System-Theoretic Accident Model and Processes(STAMP)is a widely recognized approach for accident analysis.In this paper,we propose a STAMP-Game model to analyze accidents in oil and gas storage and transportation systems.Stakeholders in accident analysis by STAMP can be regarded as players of a game.Game theory can,thus,be adopted in accident analysis to depict the competition and cooperation between stakeholders.Subsequently,we established a game model to study the strategies of both supervisory and supervised entities.The obtained results demonstrate that the proposed game model allows for identifying the effectiveness deficiency of the supervisory entity,and the safety and protection altitudes of the supervised entity.The STAMP-Game model can generate quantitative parameters for supporting the behavior and strategy selections of the supervisory and supervised entities.The quantitative data obtained can be used to guide the safety improvement,to reduce the costs of safety regulation violation and accident risk.

Numerical simulation of gas transport mechanisms in tight shale gas reservoirs

Due to the nanometer scale pore size and extremely low permeability of a shale matrix,traditional Darcy＇s law can not exactly describe the combined gas transport mechanisms of viscous flow and Knudsen diffusion.Three transport models modified by the Darcy equation with apparent permeability are used to describe the combined gas transport mechanisms in ultra-tight porous media,the result shows that Knudsen diffusion has a great impact on the gas transport and Darcy＇s law cannot be used in a shale matrix with a pore diameter less than 1 μm.A single porosity model and a double porosity model with consideration of the combined gas transport mechanisms are developed to evaluate the influence of gas transport mechanisms and fracture parameters respectively on shale gas production.The numerical results show that the gas production predicted by Darcy＇s law is lower than that predicted with consideration of Knudsen diffusion and the tighter the shale matrix,the greater difference of the gas production estimates.In addition,the numerical simulation results indicate that shale fractures have a great impact on shale gas production.Shale gas cannot be produced economically without fractures.

Underwater gas self-transportation along femtosecond laser-written open superhydrophobic surface microchannels(<100μm)for bubble/gas manipulation

Underwater transportation of bubbles and gases has essential applications in manipulating and using gas,but achieving this function at the microscopic level remains a significant challenge.Here,we report a strategy to self-transport gas in water along a laser-induced open superhydrophobic microchannel with a width less than 100μm.The femtosecond laser can directly write superhydrophobic and underwater superaerophilic microgrooves on the polytetrafluoroethylene(PTFE)surfaces.In water,the single laser-induced microgroove and water medium generate a hollow microchannel.When the microchannel connects two superhydrophobic regions in water,the gas spontaneously travels from the small region to the large area along this hollow microchannel.Gas self-transportation can be extended to laser-drilled microholes through a thin PTFE sheet,which can even achieve anti-buoyancy unidirectional penetration.The gas can overcome the bubble’s buoyance and spontaneously travel downward.The Laplace pressure difference drives the processes of spontaneous gas transportation and unidirectional bubble passage.We believe the property of gas self-transportation in the femtosecond laser-structured open superhydrophobic and underwater superaerophilic microgrooves/microholes has significant potential applications related to manipulating underwater gas.

Transport model for shale gas well leakage through the surrounding fractured zones of a longwall mine

The environmental risks associated with casing deformation in unconventional(shale)gas wells positioned in abutment pillars of longwall mines is a concern to many in the mining and gas well industry.With the recent interest in shale exploration and the proximity to longwall mining in Southwestern Pennsylvania,the risk to mine workers could be catastrophic as fractures in surrounding strata create pathways for transport of leaked gases.Hence,this research by the National Institute for Occupational Safety and Health(NIOSH)presents an analytical model of the gas transport through fractures in a low permeable stratum.The derived equations are used to conduct parametric studies of specific transport conditions to understand the influence of stratum geology,fracture lengths,and the leaked gas properties on subsurface transport.The results indicated that the prediction that the subsurface gas flux decreases with an increase in fracture length is specifically for a non-gassy stratum.The sub-transport trend could be significantly impacted by the stratum gas generation rate within specific fracture lengths,which emphasized the importance of the stratum geology.These findings provide new insights for improved understanding of subsurface gas transport to ensure mine safety.

Influence of gas transport mechanisms on the productivity of multi-stage fractured horizontal wells in shale gas reservoirs

In order to investigate the influence on shale gas well productivity caused by gas transport in nanometer- size pores, a mathematical model of multi-stage fractured horizontal wells in shale gas reservoirs is built, which considers the influence of viscous flow, Knudsen diffusion, surface diffusion, and adsorption layer thickness. A dis- crete-fracture model is used to simplify the fracture mod- cling, and a finite element method is applied to solve the model. The numerical simulation results indicate that with a decrease in the intrinsic matrix permeability, Knudsen diffusion and surface diffusion contributions to production become large and cannot be ignored. The existence of an adsorption layer on the nanopore surfaces reduces the effective pore radius and the effective porosity, resulting in low production from fractured horizontal wells. With a decrease in the pore radius, considering the adsorption layer, the production reduction rate increases. When the pore radius is less than 10 nm, because of the combined impacts of Knudsen diffusion, surface diffusion, and adsorption layers, the production of multi-stage fractured horizontal wells increases with a decrease in the pore pressure. When the pore pressure is lower than 30 MPa, the rate of production increase becomes larger with a decrease in pore pressure.

CFD simulation of effect of anode configuration on gas–liquid flow and alumina transport process in an aluminum reduction cell

Numerical simulations of gas–liquid two-phase flow and alumina transport process in an aluminum reduction cell were conducted to investigate the effects of anode configurations on the bath flow, gas volume fraction and alumina content distributions. An Euler–Euler two-fluid model was employed coupled with a species transport equation for alumina content. Three different anode configurations such as anode without a slot, anode with a longitudinal slot and anode with a transversal slot were studied in the simulation. The simulation results clearly show that the slots can reduce the bath velocity and promote the releasing of the anode gas, but can not contribute to the uniformity of the alumina content. Comparisons of the effects between the longitudinal and transversal slots indicate that the longitudinal slot is better in terms of gas–liquid flow but is disadvantageous for alumina mixing and transport process due to a decrease of anode gas under the anode bottom surface. It is demonstrated from the simulations that the mixing and transfer characteristics of alumina are controlled to great extent by the anode gas forces while the electromagnetic forces(EMFs) play the second role.

Preparation and Gas Permeation of Supported γ-Al_2O_3 Membranes Used as Substrate Layer for Microporous Membranes

γ-Al2O3 membranes were successfidly deposited on the top of porous α-Al2O3 support by sol-gel process and characterized by means of XRD , SEM, N2 adsorption and gas permeation. The γ-Al2O3 membranes, free of pin-holes and cracks, adhere tightly to the supports and have a thlekness of about 7μm. When sintered at 400 ℃ , γ-Al2O3 membranes have a rutrrow pore size distribution, with a pore diameter of 3.6nm, and the transport of both H2 and CO2 in supported γ-Al2O3 membrane is governed by Knudsen mechanism, with H2 permeance of 3.3× 10^-6 molm^-2Pa^-1s^-1 and H2/ CO2 permselectivity close to the ideal Knudsen value at 50 ℃ . The γ-Al2O3 membranes are suitable for being used as the substrates of microparoas membranes .

The Compressed Gas Thermodynamics Processes on Gas Pipelines

Transport of gas through pipelines is the most energy-intensive production. About 80% of the energy of the whole oil and gas production is used for the gas transportation through pipelines. To that end, enhancement of the efficiency and energy saving in the field of gas transport are solved with the aid of the basic thermodynamic relations which are mainly presented in this article.

Large Potential Exists in China's Oil & Gas Transportation System

As China in the decades ahead is to go through significant reorganization in the power sector and the petrochemical industry will see considerable growth,the transportation infrastructure for petroleum and gas should have a new shape. Implementing the largest infrastructure projects and creating on this basis a modern transportation network will not only see a new reincarnation of traditional industrial centers, but also open wider opportunities for regional development.

The development status and the prospect of the pipeline robots in the oil and gas storage and transportation industry

In the process of the constant development of the oil and gas storage and transportation technology, the maintenance of the large pipelines is an important task. At present, China vigorously promotes the use of the pipeline robots, for the maintenance of the oil and gas pipelines by the unique characteristics of the robots. In this paper, the author carries out the detailed analysis on the current situation of the development of the pipeline robots in the oil and gas storage and transportation industry, and compares the different applications of the pipeline robots at home and abroad. Starting from the principles of the operation of the robots, the author analyzes the characteristics of the different types of the robots, and combined with the existing conditions of the oil and gas storage and transportation in our country, the author tries to find the most favorable way of the working of the pipeline robots, to continuously improve the development of the oil and gas storage and transportation industry using the robot technologies.

The challenges facing the oil and gas storage and transportation technology and its developing direction

In recent years, our country is increasingly dependent on the use of the oil resources, and the degree of the oil mining is also continuously upgrading. After the completion of the tasks related to the oil mining in the lands, the technologies for the development of the offshore oil mining are particularly important. Among these problems, after the exploitation, the storage and transportation of the offshore oil and gas is worthy of the discussion of the technical personnel. From the experience of the oil and gas storage and transportation in the long years, in some environmentally degraded areas, there are problems in the efficiency and safety in the long pipeline transportation and the oil and gas mixed transportation, and in the transportation, there are also big shortcomings. In this paper, the author carries on the analysis of the existing questions encountering in our country＇s oil and gas storage and transportation~ and proposes the direction of the researches in the future oil and gas storage and transportation, and the purpose is to better improve the security of Cbina＇s oil and gas storage and transportation and to enhance the efficiency of the use of the oil and gas.

Current State and Prospects of CNPC's Oil and Gas Storage and Transportation

Oil and gas transportation facilities are important for a country to secure an energy supply and maintain social stability and economic development.Social capitals in China are now encouraged by the government to invest in the construction of oil and gas infrastructures in the country.With China's growing economy and new reforms in the oil and gas sector,more opportunities are available for private companies seeking to get involved in energy infrastructure.It is estimated that the future market of energy infrastructure projects in China is valued at nearly RMB 2 trillion.This paper is trying to offer some clues regarding investment in energy infrastructure in China by giving a brief introduction to the current situation of CNPC's oil and gas infrastructure construction.

Transport properties of dilute ammonia-noble gas mixtures from new intermolecular potential energy functions

Previously we have determined the dilute mixture transport properties of slightly polar fluorocarbons using the inverted intermolecular potential energies(Ind. Eng. Chem. Res. 45(2006) 9211–9223). In the present paper, the corresponding states correlations for reduced viscosity collision integrals were employed to obtain effective unlike interaction potential models for dilute binary mixtures of highly polar molecule ammonia with noble gases.The inverted potentials were fitted to the Morse–Spline–van der Waals(MSV), model potential. The method of least-squares fitting was then applied to identify best consistence force parameters for each ammonia-noble gas mixture, taking advantage of experimental viscosities, diffusion coefficients and thermal conductivities.The proposed potential models were compared with those obtained from other sources, in order to assess the extent of their validity.The potentials were later employed to calculate transport properties of the studied mixtures. Then, results were compared with those reported in the literature, which led to the acceptable agreement.

Reform Exploration for Safety Course System of Oil and Gas Storage and Transportation Facilities

In recent years,the safety of oil and gas storage and transportation facilities has been paid more attention by the state and enterprises due to frequent accidents.The oil and gas storage and transportation facilities safety courses in China University of Petroleum(Beijing)includes“Engineering mechanics”,“Strength design of pipelines and tanks”and“Safety and integrity management of oil and gas storage and transportation facilities”.The three courses lack relevance and the teaching mode is too rigid,resulting in students losing their initiative in learning.If students can’t use the knowledge flexibly,it will affect the achievement of the objectives of the training program.Therefore,oil and gas storage and transportation facilities safety courses are reformed,training plans are adjusted and teaching methods are improved.The practice shows that the reform enriches the teaching content,improves the teaching quality,stimulates classroom activity and gets a good evaluation of students.The reform of safety courses has a certain significance for cultivating compound talents who have the ability to solve practical problems in engineering.

Main Indexes of Pipeline Transportation of Crude Oil and Gas

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2013 Production of China's Shale Gas Reaches 200 Million Cubic Meters and the First Transportation Pipeline Constructed

Results of the global shale gas resources show that minable resources of global shale gas are 187 trillion cubic meters （tern）, of which China accounts for 36 tcm （about 20% of the total amount）, which is mainly distributed in the Sichuan Basin, Yangtze Terrace, and Ordos Basin. From 2009 to 2012, China completed an accumulative number of 129 drilling wells related to shale gas, including 46 investigated vertical wells, 55 exploration wells and 28 evaluation wells, with 2012 production ranging from 25 million cubic meters （mcm） to 30 mcm.

Reconcile the contradictory wettability requirements for the reduction and oxidation half-reactions in overall CO_(2) photoreduction via alternately hydrophobic surfaces

The overall photocatalytic CO_(2) reduction reaction(OPCRR)that can directly convert CO_(2) and H_(2)O into fuels represents a promising renewable energy conversion technology.As a typical redox reaction,the OPCRR involves two half-reactions:the CO_(2) reduction half-reaction(CRHR)and the water oxidation half-reaction(WOHR).Generally,both half-reactions can be promoted by adjusting the wettability of catalysts.However,there is a contradiction in wettability requirements for the two half-reactions.Specifically,CRHR prefers a hydrophobic surface that can accumulate more CO_(2) molecules on the active sites,ensuring the appropriate ratio of gas-phase(CO_(2))to liquid-phase(H_(2)O)reactants.Conversely,the WOHR prefers a hydrophilic surface that can promote the departure of the gaseous product(O_(2))from the catalyst surface,preventing isolation between active sites and the reactant(H_(2)O).Here,we successfully reconciled the contradictory wettability requirements for the CRHR and WOHR by creating an alternately hydrophobic catalyst.This was achieved through a selectively hydrophobic modification method and a charge-transfer-control strategy.Consequently,the collaboratively promoted CRHR and WOHR led to a significantly enhanced OPCRR with a solar-to-fuel conversion efficiency of 0.186%.Notably,in ethanol production,the catalyst exhibited a 10.64-fold increase in generation rate(271.44μmol g^(-1)h~(-1))and a 4-fold increase in selectivity(55.77%)compared to the benchmark catalyst.This innovative approach holds great potential for application in universal overall reactions involving gas participation.

Confinement effect on CO_(2)and CH_(4)permeability in shale

Gas flow in shales follows a number of physical mechanisms that include Knudsen diffusion,Darcy flow,and adsorption in the matrix and micro pores.The aim of the study is to resolve the interplay of gas transport in these media at increased effective stress as well as net pore pressure.In this research,we investigated the nature of gas transport in the matrix of shale by sending He,CH_(4)and CO_(2)gases through a transient upstream pressure pulse decay instrument.A series of experiments were conducted at constant pore pressures and a gradually increasing confining pressure.The same study was done in three different scenarios,injecting He,CO_(2)and CH_(4).At a constant pore pressure,gas permeability appears to decrease with an increasing confining pressure and effective stress.With increasing effective stress,the slip factor also decreases along with the permeability.The decrease in slip could be attributed to prestressing,that is likely to create new fractures.Among the three purged gases,permeability of shale to CH_(4)is the highest,and that to CO_(2)is the lowest owing to its high adsorption.Higher permeability of CH_(4)against He,could be attributed to the dual transport mechanism.