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Study of 3-D Numerical Simulation for Gas Transfer in the Goaf of the Coal Mining
In order to simulate field distribution rules, mathematical models for 3-D air flows and gas transfer in the goaf of the coal mining are established, based on theories of permeability and dynamic dispersion through porous media. A gas dispersion equation in a 3-D field is calculated by use of numerical method on a weighted upstream multi-element balance. Based on data of an example with a U type ventilation mode, surface charts of air pressure distribution and gas concentration are drawn by Graphtool software. Finally, a comparison between actually measured results in the model test and the numerical simulation results is made to proves the numerical implementation feasible....
2020-09-15 12:28:59浏览：46
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Study on the threshold value of organic enrichment of carbonate as gas source rocks
In this paper, calculations have been performed about gas quantity of generation, adsorption, dissolving in oil, dissolving in water, diffusion of unit area carbonate rocks at different geologic conditions in the Tarim basin. According to the material balance principle, the corresponding organic carbon content when gas started expelling from source rocks with separate phases has been worked out. We regard it as the theoretical threshold value (TOCmin) of gas source rocks under the same geologic condition. Based on the simulating calculation, a fact has been discovered that TOCmin decreases with the increasing source rocks thickness, decreases at the beginning and then increases with the increasing maturity and decreases with the better type of organic matter. TOCmin evaluation table of carbonate gas source rocks in the Tarim basin has been established. Investigations indicate that the TOCmin of carbonate gas source rocks varies greatly with the differences of geologic conditions, and gas source rocks cannot be evaluated with a unified TOC threshold value. And we also establish a preliminary evaluation table of TOC industrial threshold value, TOCgy, of carbonate gas source rocks in the Tarim basin....
2020-09-15 12:28:59浏览：68
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Stability of stratified flow and slugging in horizontal gas-liquid flow
A transient one-dimensional two-fluid model is proposed to investigate numerically the interfacial instability and the onset of slugging for liquid-gas flow in a horizontal duct. In the present model, the effects of surface tension and transverse variations in dynamic pressure are taken into account. The evolution of interfacial disturbances is displayed and compared with the linear viscous KelvinHelmholtz stability analyses. It shows that interfacial wave is more instable due to the non-linear effect. The model predicts well the stability limit of stratified flow in comparison with the experimental data, and also automatically tracks the onset of slugging. The results show that the initiation of hydrodynamic slugging is related to local interfacial instability. Based on the cycle of slugging, a model for slug frequency is presented, which predicts the trends of slug frequencies with gas/liquid flow rate well in comparison with the available data. The effects of physical properties on slugging have been examined. It is found that with the increase in the gas viscosity and liquid density the slugging would be inhibited, whereas, with the increase in liquid viscosity and gas density, the slugging can be promoted....
2020-09-15 12:28:59浏览：66
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Gas formation mechanism of marine carbonate source rocks in China
By breaking through the conventional ideology on the study of gas-formation mechanism of source rocks which focused on merely the characteristics of source rocks themselves, and based on the development and distribution characteristics of marine carbonate source rocks in the medium-to-bottom parts of the Chinese superimposed sedimentary basins as well as various processes in the course of gas generation and reservoir forming, the complex hydrocarbon-generating model of carbonates is established. Such a model concerns not only the "three-stage" gas formation characteristics of carbonates, but also the gas generation process due to a thermal cracking of oil and the re-generation process of gas from heated secondary organic matters during the gas-generation and reservoir-forming course. The high-quality hydrocarbon generating matter of marine carbonate source rocks determined a high gas-oil ratio and tended to form paleo-oil-reservoirs, representing an enrichment process of organic matters. The thermal cracking of oil in palaeo-oil-reservoirs is an important means for the effective formation of gas reservoirs. The secondary organic matters in carbonate reservoirs may regenerate gas after a secondary deep burial, thus becoming an effective gas source....
2020-09-15 12:28:59浏览：82
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An accurate empirical correlation for predicting natural gas compressibility factors
The compressibility factor of natural gas is an important parameter in many gas and petroleum engineering calculations.This study presents a new empirical model for quick calculation of natural gas compressibility factors.The model was derived from 5844 experimental data of compressibility factors for a range of pseudo reduced pressures from 0.01 to 15 and pseudo reduced temperatures from 1 to 3.The accuracy of the new empirical correlation has been compared with commonly used existing methods.The comparison indicates the superiority of the new empirical model over the other methods used to calculate compressibility factor of natural gas with average absolute relative deviation percent (AARD％) of 0.6535....
2020-09-15 12:28:59浏览：49
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The distribution of phenylalkanes in the modern sediment associated with gas hydrate from the Gulf o
Phenylalkanes with carbon numbers between 16 and 19,characterized by the main carbon-18,have been identified in the mod-em sediments collected from gas hydrate area from the Gulf of Mexico.The structure of phenylalkanes with four isomers for ever-y carbon number was determined by means of their mass spectra and previous studies.The distribution of the series character-ized by a low molecular mass was similar to the distribution of n-alkane,alkylcyclohexanes and alkylbenzenes in each sample.There were differences in the distribution of the phenylalkane series between the S - 1,S - 4,S - 7,S - 9 samples and the S -8,S - 10 and S - 11 samples.The phenylalkanes might be derived from Archaea associated with anaerobic oxidation of methane (AOM) processes in S - 1,S - 4,S - 7 and S - 9 samples according to their distribution resembled with the distribution of the extract from a type of Archaea.The distribution of alkylcyclobexanes and alkylbenzenes in S - 1,S - 4,S - 7 and S - 9 sample was found to be similar to each other.The odd-over-even predominance of alkylcyclohexanes was seen as the input of some bac-terial....
2020-09-15 12:28:59浏览：30
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Extended research of showing means of GIS in the development and management of oil and gas reservoir
Owing to the close correlation of development of oil and gas reservoir and spatial geological place, the technique of GIS can be introduced into the process of development and management of oil and gas reservoir. But development of oil and gas reservoir has its particularity, development and management GIS of oil and gas reservoir should use the other techniques to extend the forms of representation to make up the shortages of GIS in representation. The development and management GIS of oil and gas reservoir will be perfect besides the basic functions of GIS. This paper expatiates how to use other techniques to extend GIS in development and management of oil and gas reservoir mainly from productive dynamic curve of well, layers of map piling up, 3-D geological model and replaying maps, etc. Through extended GIS in development and management of oil and gas reservoir, the forms of representation of geological information are enriched,representations of information are more direct and visual, spatial descriptive ability and forms of representation of GIS are built up and the single information system will be developed into a management and decision-making system....
2020-09-15 12:28:59浏览：48
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Destruction mechanism of gas explosion to ventilation facilities and automatic recovery technology
In order to overcome the heavy casualties caused by gas explosion,we verified the propagation law of shock wave in pipeline and the overpressure distribution of gas explosion by similar experiments according to the analyses of reasons for casualty and ventilation system model destroyed by gas explosion in the mining face.We summarized the gas composition after the explosion and its danger,analyzed the effects of the gas explosion shock wave to ventilation system and facilities and the laws of toxic gas spread and diffusion in the ventilation network after the explosion.We presented a technical proposal to control the smoke and recover the ventilation system after a gas explosion and developed a reserve air door and control system that were embed in the lane,and could close automatically in conditions of no pressure and electricity.The results showed that the reserve air door normally opened and could close automatically controlling the smoke flow and resuming the ventilation system when the gas explosion shock wave destroyed the original shutting air door which resulted in the air short circuit....
2020-09-15 12:28:59浏览：45
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Research on Axial Trail of High-Speed Gas Painting Automizor
The non-linear dynamic model is set up of one type of high-speed painting automizor with gas supporting system. The stability of motion and dynamic response of the gas painting automizor system are studied over a relatively wide range of rotating speed by numerical analytic method, the critical velocity under working condition is found, and rotate stability and critical condition are discussed in theory. Furthermore, the range of the critical parameter of the system when Hopf bifurcation occurs and the law between axis trace and bearing clearance are acquired, too....
2020-09-15 12:28:59浏览：40
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Experimental Investigation on Ablation Characteristic of EPDM Insulator in Different Gas Environment
Some ablation experiments of Ethylene-Propylene-Diene Monomer (EPDM) insulator were carried out in quasi-static low temperature gas environment, gas-phase environment, two-phase environment with Al2O3 grain and high concentration Al2O3 grain gas environments. Their charring ablation rate, thickness, surface morphology and main ingredient of the charring layer were analyzed. The experiment results show that the main influent factors for the charring ablation rate are the gas temperature, grain concentration and state of grain impact; the main influent factors for the charring layer thickness are the gas velocity and environment pressure; and the process of SiO2 migrating in the charring layer occur commonly in different gas environments. They provide a foundation for the ablation mechanism research and modeling of EPDM insulator....
2020-09-13 23:35:02浏览：35
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Research and Application of New Methods to Oil-Gas Geochemical Exploration
Based on the results of researches and applications for many years, it has been discovered that new methods and techniques for geochemical exploration of oil and gas such as D C, altered carbonate, Hg in absorption phase, Ks, Fe2+, d 13C, fluorescence in two and three dimensions, and N2 and O2 in heat release can give full play in the following five fields: (1) optimization of the favourable target or hollow zones and structural zones in a region; (2) evaluation of oil traps and delineation of prospective oil and gas areas; (3) prediction of deep-seated oil-bearing horizons; (4) evaluation of the genesis of oil and gas geochemical anomalies and determination of the types of oil and gas accumulations; (5) forecast of the burial depths of oil and gas pools....
2020-09-13 23:35:02浏览：37
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Research on the explosion characteristics of chlorine dioxide gas
The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 201.The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO2]/[airl),whereas there is no corresponding upper concentration limit.The maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO2 and 0.641 MPa at 90% ClO2.The induction time (the time from the moment of sparking to explosion) at 10% ClO2 was 2195 ms,but at 90% ClO2 the induction time was just 8 ms.The explosion reaction mechanism of ClO2 is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl2O3),from which the chain branching occurs....
2020-09-13 23:35:02浏览：70
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Gas and pressure effects on the synthesis of amorphous carbon nanotubes
The effects of gas, pressure and temperature on the production of amorphous carbon nanotubes were investigated using an arc discharging furnace at controlled temperature. Co/Ni alloy powder was used as catalyst.The discharge current was 80 A and voltage was 32 V. The optimal parameters were obtained: 600℃ temperature, hydrogen gas and 500 torr pressure. The productivity and purity of amorphous carbon nanotubes are 6.5 gram per hour and 80%, respectively. The diameter of the amorphous carbon nanotubes is about 7-20 nm....
2020-09-13 23:35:02浏览：53
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Effects of salinity on methane gas hydrate system
Using an approximately analytical formation,we extend the steady state model of the pure methane hydrate system to include the salinity based on the dynamic model of the methane hydrate system.The top and bottom boundaries of the methane hydrate stability zone (MHSZ) and the actual methane hydrate zone (MHZ),and the top of free gas occurrence are determined by using numerical methods and the new steady state model developed in this paper.Numerical results show that the MHZ thickness becomes thinner with increasing the salinity,and the stability is lowered and the base of the MHSZ is shifted toward the seafloor in the presence of salts.As a result,the thickness of actual hydrate occurrence becomes thinner compared with that of the pure water case.On the other hand,since lower solubility reduces the amount of gas needed to form methane hydrate,the existence of salts in seawater can actually promote methane gas hydrate formation in the hydrate stability zone.Numerical modeling also demonstrates that for the salt-water case the presence of methane within the field of methane hydrate stability is not sufficient to ensure the occurrence of gas hydrate,which can only form when the methane concentration dissolved in solution with salts exceeds the local methane solubility in salt water and if the methane flux exceeds a critical value corresponding to the rate of diffusive methane transport.In order to maintain gas hydrate or to form methane gas hydrate in marine sediments,a persistent supplied methane probably from biogenic or thermogenic processes,is required to overcome losses due to diffusion and advection....
2020-09-13 23:35:02浏览：25
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Characteristics of carbonate gas pool and multistage gas pool formation history of Hetianhe gas fiel
Hetianhe is a big carbonate gas field which is found and demonstrated in the period of "Chinese National Ninth 5-Year Plan". The proved reserve of Hetianhe gas field is over 600×108 m3. Its main producing layers are Carboniferous bioclastic limestone and Ordovician carbonate composed of buried hill. The former is stratified gas pool with water around its side, and the latter is massive gas pool with water in its bottom. The gases in the gas pools belong to dry gases with normal temperature and pressure systems. Based on the correlation of gas and source rock, the gases are mainly generated from Cambrian source rocks. According to the researches on source rock and structure evolution, and the observations on the thin section to reservoir bitumen and the studies on homogenization temperature of fluid inclusions, the gas pool has been identified and divided into three formation periods. The first is Late Caledonian when the oil generated from the Cambrian source rocks and migrated along faults, as a form of liquid facies into Ordovician carbonate reservoir and accumulated there. After that, the crust uplifted, the oil reservoir had been destroyed. The second is Late Hercynian when condensate gases generated from the Cambrian source rocks and migrated into Ordovician reservoir, as a form of liquid facies. Since the fractures had reached P strata, so the trap might have a real poor preservation condition, and the large-scale gas pool formation had not happened. The third gas reservoir formation period occurred in Himalaya. The fractures on both sides of Hetianhe gas field developed violently under the forces of compression, and thus the present fault horst formed. The dry gases generated from Cambrian source rocks and migrated upwards as the form of gas facies into Ordovician and Carboniferous reservoirs, and the large gas pool as discovered at present was formed finally....
2020-09-13 23:35:02浏览：72
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