By investigating the evolution of shale gas generation,storage,adjustment and accumulation under different structural settings in superimposed basins,this study elucidates the differential accumulation mechanisms of s...By investigating the evolution of shale gas generation,storage,adjustment and accumulation under different structural settings in superimposed basins,this study elucidates the differential accumulation mechanisms of shale gas.An improved evaluation method of shale gas content evolution in superimposed basins is proposed.This method incorporates the coupling effect of key geological factors such as temperature,pressure,organic matter abundance,maturity,and pore characteristics on the content and occurrence state of shale gas,as well as the configuration relationship between shale gas generation and storage throughout geological history.Using this approach,the gas evolution histories of the Longmaxi Formation shales in wells N201 and PY1 are reconstructed under varying geological conditions.The Longmaxi Formation shales in these wells are dominated by typeⅠkerogen,with original total organic carbon(TOC_(o))contents of 6.20 wt% and 4.92 wt%,respectively,indicating differences in the initial material basis for gas generation.At the maximum burial depth of approximately 5000 m,the Longmaxi Formation shale in well N201 exhibits a formation pressure coefficient of 2.05,an organic matter maturity of 2.2%,and organic pores accounting for 68%of the total porosity.The gas generation quantity(Q_(g))reaches 19.24 m^(3)/t,while the gas storage capacity(Q_(s))is 4.30 m^(3)/t.The actual total gas content(Q_(a)),constrained by Q_(s),is 4.30 m^(3)/t,with free gas comprising 94%.Following relatively moderate tectonic uplift,the Q_(a) in well N201 decreases to 4.03 m^(3)/t,with free gas accounting for 63%.In contrast,the Longmaxi Formation shale in well PY1 reached a maximum burial depth of 6300 m,associated with a formation pressure coefficient of 1.62,organic matter maturity of 2.5%,and organic pore proportion of 67%.Here,Q_(g) is 16.87 m^(3)/t,and both Q_(s) and Q_(a) are 3.65 m^(3)/t,with free gas accounting for 98%.After intense tectonic uplift,Q_(a) declines to 2.72 m^(3)/t,and the proportion of free gas drops to51%.Finally,a four-stage differential accumulation model of shale gas is established:Slow gas generation and only adsorbed gas occur in stageⅠ,which is primarily controlled by TOC content;both adsorbed gas and free gas present in stageⅡ,with free gas becoming dominant;rapid gas generation and free gas predominance are controlled by temperature and porosity in stageⅢ;and gas adjustment and accumulation are primarily controlled by temperature and pressure in stageⅣ.展开更多
Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the...Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the integrity of gas content within samples and are often constrained by estimation errors inherent in empirical formulas,which results in inaccurate gas content measurements.This study introduces a lightweight,in-situ pressure-and gas-preserved corer designed to collect coal samples under the pressure conditions at the sampling point,effectively preventing gas loss during transfer and significantly improving measurement accuracy.Additionally,a gas migration model for deep coal mines was developed to elucidate gas migration characteristics under pressure-preserved coring conditions.The model offers valuable insights for optimizing coring parameters,demonstrating that both minimizing the coring hole diameter and reducing the pressure difference between the coring-point pressure and the original pore pressure can effectively improve the precision of gas content measurements.Coring tests conducted at an experimental base validated the performance of the corer and its effectiveness in sample collection.Furthermore,successful horizontal coring tests conducted in an underground coal mine roadway demonstrated that the measured gas content using pressure-preserved coring was 34%higher than that obtained through open sampling methods.展开更多
Currently,regression prediction methods based on logging data is one of the main methods for analyzing gas content of coal seams.However,the complexity of logging parameters for deep coal seams and the scarcity of mea...Currently,regression prediction methods based on logging data is one of the main methods for analyzing gas content of coal seams.However,the complexity of logging parameters for deep coal seams and the scarcity of measured gas content data signifcantly afects the accuracy and generalizability of data regression models.Accurately predicting the gas content of coal seams under small-sample condition become a difcult point in deep coalbed methane(CBM)exploration.The ModelAgnostic Meta-Learning(MAML)and Support Vector Regression(SVR)algorithms are among the few suitable for smallsample learning,exhibiting strong adaptability under limited sample conditions.In this study,logging parameters are used as input variables to construct MAML and SVR models,and their performance in predicting gas content of deep coal seams across diferent regions and layers is compared.The results demonstrate that the MAML algorithm efectively addresses the complex relationships between gas content of deep coal seam and logging parameters.The prediction errors for test dataset and new samples are merely 3.61%and 4.52%respectively,indicating exceptional adaptability,robust generalization capability,and stable model performance.In contrast,the dependency of SVR model on input parameters restricts its accuracy and generalizability in predicting gas content in deep coal seams with varying geological conditions.Although achieving a test dataset error of 4.71%,the SVR model demonstrates substantially degraded performance when applied to novel samples,with prediction errors escalating to 12.46%.Therefore,the MAML model is selected to predict gas content in the unknown areas of the Baijiahai region.The prediction results reveal that the gas content of coal seams in the Xishanyao formation(J2x)ranges from 1.32 m^(3)/t to 16.11 m^(3)/t,while that in the Badaowan Formation(J1b)varies between 1.73 m^(3)/t and 11.27 m^(3)/t.Notably,the gas enrichment areas are predominantly distributed in well blocks adjacent to fault systems,such as wells C31 and BJ8,etc.,which align with the favorable geological conditions for deep CBM accumulation in the Baijiahai region.These spatial distribution patterns not only corroborate existing geological insights but also further validate the reliability of the MAML model in predicting gas content within deep coal seams.展开更多
As an important form of reactors for gas/liquid/solid catalytic reaction,trickle bed reactors (TBRs) are widely applied in petroleum industry,biochemical,fine chemical and pharmaceutical industries because of their fl...As an important form of reactors for gas/liquid/solid catalytic reaction,trickle bed reactors (TBRs) are widely applied in petroleum industry,biochemical,fine chemical and pharmaceutical industries because of their flexibility,simplicity of operation and high throughput.However,TBRs also show inefficient production and hot pots caused by non-uniform fluid distribution and incomplete wetting of the catalyst,which limit their further application in chemical industry.Also,process intensification in TBRs is necessary as the decrease in quality of processed crude oil,caused by increased exploitation depths,and more restrictive environmental regulations and emission standards for industry,caused by increased environment protection consciousness.In recent years,lots of strategies for process intensification in TBRs have been proposed to improve reaction performance to meet the current and future demands of chemical industry from the environmental and economic perspective.This article summarizes the recent progress in techniques for intensifying gas/liquid/solid reaction in TBRs and application of intensified TBRs in petroleum industry.展开更多
This study presents a systematic investigation of pressure drop and gas holdup in an upward-flow fixedbed reactor,examining the effects of bubble size,bed height,particle shape,superficial gas velocity(SGV),and superf...This study presents a systematic investigation of pressure drop and gas holdup in an upward-flow fixedbed reactor,examining the effects of bubble size,bed height,particle shape,superficial gas velocity(SGV),and superficial liquid velocity(SLV)based on experimental measurements and empirical correlations.Two bubble generators,namely ring tube generator(RTG)and porous sintered film generator(PSG),are used.Key findings reveal that for the PSG,increasing SGV decreases small-bubble population while promoting large-bubble formation,with the bubbles stabilizing at a Sauter mean diameter(d_(32))of~3 mm.The RTG produces stable large bubbles(d_(32)=6—7 mm)with minimal size variations across the range of tested SGVs.The pressure drop decreases with an increase in SGV but increases with higher SLV and bed height,primarily due to the reduced liquid holdup and the dominance of static pressure.Smaller bubbles reduce the pressure drop by slowing rise velocity and minimizing frictional resistance.Clover-shaped particles exhibit the highest pressure drop owing to large porosity,while 3-mm toothed spheres show higher pressure drop than 5-mm spheres at high SGV because of intensified capillary forces.The gas holdup increases with increasing SGV and bed height but decreases slightly with increasing SLV.Smaller bubbles enhance gas holdup by improving bed distribution and residence time.The 3-mm toothed spheres show the highest gas holdup due to stronger capillary trapping,whereas the clover-shaped particles exhibit the lowest.Empirical correlations for pressure drop and gas holdup are developed,yielding calculation errors within±1%and±20%of the experimental values,respectively.展开更多
The methane adsorption capacity,gas content,and carbon isotope characteristics of coal are crucial parameters that determine the productivity of coalbed methane(CBM)wells and their development potential.In this paper,...The methane adsorption capacity,gas content,and carbon isotope characteristics of coal are crucial parameters that determine the productivity of coalbed methane(CBM)wells and their development potential.In this paper,test analyses of methane adsorption,gas content and carbon isotope of methane were carried out using 89 samples from the No.3 coal seam in the southwestern part of the Qinshui Basin.Their characteristics and correlations were analyzed.A relationship model between methane adsorption,gas content,carbon isotopes,coal metamorphism and material composition were established,and its controlling mechanism was investigated.The results indicate that the distribution patterns of Langmuir volume and Langmuir pressure in No.3 coal seam are mainly determined by the material composition and the thermal evolution level.The methane gas content in coal is mainly affected by the burial depth,microcosmic co mposition,mineral conte nt,moisture content and ash yield,adsorption capacity and metamorphism of the coal.The methane carbon isotope(δ^(13)C_(1))values in the natural desorbed gas from No.3 coal seam range from-26.95%to-57.80‰,with a mean value of-34.53‰.δ^(13)C_(1)in coal shows a two-stage variation pattern with increasing in vitrinite reflectance(R_(max)^(o)).When R_(max)^(o)is blow 3.0%,δ^(13)C_(1)values of methane in coal become progressively heavier with increasing R_(max)^(o).When R_(max)^(o)reaches or exceeds 3.0%,δ^(13)C_(1)values exhibit a lightning trend with furth er increases in R_(max)^(o),which is primarily controlled by the carbon isotope fractionation effects during thermal evolution.展开更多
Bubble column reactors fitted with tube bundles(BCR TB)belong to common heat transfer equipment in the field of chemical engineering,yet the complicated thermal-hydraulics performance of BCR TB has not been deeply rev...Bubble column reactors fitted with tube bundles(BCR TB)belong to common heat transfer equipment in the field of chemical engineering,yet the complicated thermal-hydraulics performance of BCR TB has not been deeply revealed.To fill this gap,the present study proposes a novel variable bubble size modeling approach based on the Euler-Euler two-fluid framework,which is coupled with the population balance model considering comprehensive interphase forces.On the basis of verifying numerical reliability using experimental data,the mechanism of bubble swarm flow around the tube bundle and the effects of gas sparger configurations on the thermal-hydraulics performance of BCR TB are investigated.Results indicate that the entire tube bundle can be divided into three distinct zones,namely the sparger effect zone,fully developed zone and interface effect zone in view of the local mixture-to-wall heat transfer coefficient.The maximum peak value of the mixture-to-wall heat transfer coefficient always appears at 210°of heat exchange tubes.When the orifice diameter is 4 mm,the axial gradient of gas holdup is relatively large due to more intense shearing and fragmentation effects.Interestingly,the fractions of medium-sized and large-sized bubbles are not sensitive to orifice angle.Both the mixture-to-wall heat transfer coefficient and the friction factor decrease initially and then increase when the installation height increases.Under the optimized gas sparger structure configuration,the mixture-to-wall heat transfer coefficient increases by 10.23%,accompanied by the reduction of pressure drop by 8.14%,ultimately attaining a system energy conversion efficiency of 97.88%and performance evaluation criterion of 1.087.Finally,a new dimensionless and semi-theoretical Nusselt correlation incorporating a structural correction factor with an average absolute deviation of 5.15%is developed.The findings can offer useful guidance for the optimal design of BCR TB.展开更多
The Lower Cambrian shales in the Sichuan Basin are considered one of the most promising shale gas resources in China.However,large-scale commercial development has not been achieved due to the relatively low and signi...The Lower Cambrian shales in the Sichuan Basin are considered one of the most promising shale gas resources in China.However,large-scale commercial development has not been achieved due to the relatively low and significantly variable gas contents of the drilled shales.Excitingly,the first major breakthrough in deep and ultra-deep Lower Cambrian shale gas was made recently in the well Z201 in the southern Sichuan Basin,with a gas yield exceeding 73×10^(4)m^(3)/d.The success of well Z201 provides a favorable geological case to reveal the distinct enrichment mechanism of deep and ultra-deep Lower Cambrian shale gas.In this study,at drilling site of well Z201,fresh shale core samples with different gasin-place contents were collected,and their geochemical,pore development and water-bearing characteristics were analyzed systematically.The results showed that the Z201 organic-rich shales reached an overmature stage,with an average Raman maturity of 3.70%.The Z201 shales with high gas-in-place contents are mainly located in the Qiongzhusi 12section and the upper Qiongzhusi 11section,with an average gas-in-place content of 10.08 cm^(3)/g.Compared to the shales with low gas-in-place contents,the shales with high gas-in-place contents exhibit higher total organic carbon contents,greater porosities,and lower water saturations,providing more effective pore spaces for shale gas enrichment.The effective pore structures of the deep and ultra-deep Lower Cambrian shales are the primary factors affecting their gas-in-place contents.Similar to the shales with high gas-in-place contents of well Z201,the deep and ultra-deep Lower Cambrian shales in the Mianyang-Changning intracratonic sag,especially in the Ziyang area,generally developed in deep-water shelf facies with high total organic carbon contents and thick sedimentary thickness,providing favorable conditions for the development and preservation of effective pores.Therefore,they are the most promising targets for Lower Cambrian shale gas exploration.展开更多
High-pressure gas injection has proved to be an effective disruption mitigation tech- nique in DIII-D tokamak experiments. If the method can be applied in future tokamak reactors not only for disruption mitigation but...High-pressure gas injection has proved to be an effective disruption mitigation tech- nique in DIII-D tokamak experiments. If the method can be applied in future tokamak reactors not only for disruption mitigation but also for plasma termination and fueling, it will have an attractive advantage over the pellet and liquid injection from the viewpoint of economy and engineering design. In order to investigate the feasibility of this option, a study has been carried out with relevant parameters for conveying tubes of different geometrical sizes and for different gases. These parameters include pressure drop, lagger time after the valve＇s opening, gas diffusion in an ultra-high vacuum condition, and particle number contour.展开更多
Increasingly high requirement driven by environmental concern leads to more rigorous standards for sulfur dosage in fuel. Natural gas desulfurization is an important unit for industrial natural gas process. Catalytic ...Increasingly high requirement driven by environmental concern leads to more rigorous standards for sulfur dosage in fuel. Natural gas desulfurization is an important unit for industrial natural gas process. Catalytic membrane reactor for sulfur compounds removal is a newly emerged and integrated membrane technology. We reviewed the current progress for desulfurization of natural gas with membrane process, and predicted that the process combined with catalytic membrane reactor and microwave irradiation for desulfurization of natural gas might be an integrated and promising unit for large scale desulfurization with high efficiency.展开更多
Based on the data of regional geology,seismic,drilling,logging and production performance obtained from 94 major petroliferous basins worldwide,the global coal resources were screened and statistically analyzed.Then,u...Based on the data of regional geology,seismic,drilling,logging and production performance obtained from 94 major petroliferous basins worldwide,the global coal resources were screened and statistically analyzed.Then,using established definition methods and evaluation criteria for coal-rock gas in China,and by analogy with the tectono-sedimentary and burial-thermal evolution conditions of coal rocks in sedimentary basins within China,the geological resource potential of global coal-rock gas was estimated mainly by the volume method,partly by the volumetric method in selected regions.According to the evaluation indicator system comprising 14 parameters under 5 categories and the associated scoring criteria,the target basins were ranked,and the future research targets for these basins were proposed.The results reveal that,globally,coal rocks are primarily formed in four types of swamp environments within four categories of prototype basins,and distributed across five major coal-forming periods and eight coal-accumulation belts.The total geological coal resources are estimated at approximately 42×10^(12)t,including 22×10^(12)t in the strata deeper than 1500 m.The global geological coal-rock gas resources in deep strata are roughly 232×10^(12)m^(3),of which over 90%are endowed in Russia,Canada,the United States,China and Australia,with China contributing 24%.The top 10 basins by coal-rock gas resource endowment,i.e.Alberta,Kuznetsk,Ordos,East Siberian,Bowen,West Siberian,Sichuan,South Turgay,Lena-Vilyuy and Tarim,collectively hold 75%of the global total.The Permian,Cretaceous,Carboniferous,Jurassic,and Paleogene-Neogene account for 32%,30%,18%,10%,and 7%of total coal-rock gas resources,respectively.The 10 most practical basins for future coal-rock gas exploration and development are identified as Alberta,Ordos,Kuznetsk,San Juan,Sichuan,East Siberian,Rocky Mountain,Bowen,Junggar and Qinshui.Propelled by successful development practices in China,coal-rock gas is now entering a phase of theoretical breakthrough,technological innovation,and rapid production growth,positioning it to spearhead the next wave of the global unconventional oil and gas revolution.展开更多
Natural gas hydrate in Class Ⅰ reservoirs holds significant commercial potential,as demonstrated by production trials in the South China Sea.However,experimental studies have focused largely on Class Ⅲ systems,with ...Natural gas hydrate in Class Ⅰ reservoirs holds significant commercial potential,as demonstrated by production trials in the South China Sea.However,experimental studies have focused largely on Class Ⅲ systems,with Class Ⅰ/Ⅱ reservoirs remaining underrepresented due to the difficulties in simulating the geothermal gradient and interlayer interactions.This study investigates depressurization performance across all three classes using a novel 360°rotatable reactor with segmented temperature control,enabling precise simulation of reservoir conditions.Results reveal:(i)Class Ⅰ shows two-stage gas production,with 50%from early free gas enabling rapid depressurization,followed by dissociated gas dominance.They achieve 38.4%-78.3%higher cumulative production and superior gas-to-water ratios due to efficient energy use.(ii)The free gas layer in Class Ⅰ accelerates pressure and heat transfer.Class Ⅱ’s water layer provides sensible heat but causes water blocking,impairing heat flow.Class Ⅲ exhibits rapid initial dissociation but a quick decline without fluid support.(iii)Low temperature,low hydrate saturation,and high production pressure collectively reduce efficiency by increasing flow resistance,limiting gas supply,and reducing dissociation drive.Over-depressurization risks hydrate reformation and ice blockage.This work bridges experimental gaps for Class Ⅰ/Ⅱ reservoirs,offering key insights for optimizing recovery.展开更多
[Objectives]To determine the content of Zhuang medicine Sauropus spatulifolius Beille from Guangxi.[Methods]The amino acid content of S.spatulifolius Beille was determined by ultraviolet spectrophotometry(UVs).The con...[Objectives]To determine the content of Zhuang medicine Sauropus spatulifolius Beille from Guangxi.[Methods]The amino acid content of S.spatulifolius Beille was determined by ultraviolet spectrophotometry(UVs).The content of kaempferol-3-O-gentiobioside in S.spatulifolius Beille was determined by liquid chromatography-mass spectrometry(LC-MS).Pesticide residues in S.spatulifolius Beille were detected by gas chromatography-mass spectrometry(GC-MS).Heavy metal elements arsenic(As),cadmium(Cd),and lead(Pb)in S.spatulifolius Beille were detected by inductively coupled plasma mass spectrometry(ICP-MS).[Results]The amino acid content in S.spatulifolius Beille was 3.233 mg/g,with a relative standard deviation(RSD)of 0.36%.The content of kaempferol-3-O-gentiobioside was 1.15μg/mL.No pesticide residues or heavy metals were detected in the S.spatulifolius Beille medicinal material.[Conclusions]This study improves the quality control system for S.spatulifolius Beille and provides a reference basis for the quality standard control of Zhuang medicine S.spatulifolius Beille from Guangxi.展开更多
Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioact...Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioactivity of At.ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al2O3 powder,but the biooxidation rate of Fe2＋ decreases markedly from 0.23 g/（L·h） to 0.025 g/（L·h） with increasing the content of Al2O3 powder from 0 to 50%（mass fraction） in the stirred-tank probably due to the deactivation of At.ferrooxidans resulting from the collision and friction of solid particles.The increase in Al2O3 content has a little adverse effect on the bioactivity of At.ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors.The biooxidation rate of Fe2＋ in the rotating-drum is higher than that in the stirred-tank at the same content of Al2O3 powder,especially at high solid content.The higher bioactivity of At.ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor,but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al2O3 powder and sulfide minerals.展开更多
Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus...Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality.Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit(ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit(MCF) method, based on the 'bidisperse' diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation(USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, the ACF and MCF methods, are the best options respectively.展开更多
Comprehensive quantitative evaluation of shale gas content and the controlling factors in different occurrence states is of great significance for accurately assessing gas-bearing capacity and providing effective well...Comprehensive quantitative evaluation of shale gas content and the controlling factors in different occurrence states is of great significance for accurately assessing gas-bearing capacity and providing effective well-production strategies. A total of 122 core samples from well JY-A in the Fuling shale gas field were studied to reveal the characteristics of S_1 l shale,15 of which were selected to further predict the shale gas content in different occurrence states, which are dependent on geological factors in the thermal evolution process. Geological parameters were researched by a number of laboratory programs, and the factors influential in controlling shale gas content were extracted by both PCA and GRA methods and prediction models were confirmed by the BE method using SPSS software. Results reveal that the adsorbed gas content is mainly controlled by TOC, Ro, SSA, PD and pyrite content, and the free gas content is mainly controlled by S_2, quartz content, gas saturation and formation pressure for S_1 l in well JY-A. Three methods, including the on-site gas desorption method, the empirical formula method, and the multiple regression analysis method were used in combination to evaluate the shale gas capacity of well JY-A, all of which show that the overall shale gas content of well JY-A is in the range of 2.0–5.0 m^3/t and that the free gas ratio is about 50%, lower than that of well JY-1. Cause analysis further confirms the tectonics and preservation conditions of S_1 l in the geological processes, especially the influence of eastern boundary faults on well JY-A, as the fundamental reasons for the differences in shale gas enrichment in the Jiaoshiba area.展开更多
The key of the direct method of determining coalbed gas content is how to shorten the coal core exposure time in the sampling progress and reduce measuring error of gas content which comes from the calculation of losi...The key of the direct method of determining coalbed gas content is how to shorten the coal core exposure time in the sampling progress and reduce measuring error of gas content which comes from the calculation of losing gas content. The coring tests were carried out in No.24 drilling field of 715 floor gateway in Qinan Coal Mine by using traditional drill core bar- rel sampler and self-designed reversion seal coring equipment. The losing gas content was calculated by power functional method, and the gas content of two coring methods was determined, respectively. Results show that, compared with traditional drill core barrel sampling, the newly seal coring equipment can significantly shorten the coal core exposure time, the 30 min desorption gas content increases obviously, the calculation of losing gas content reduces by 56.99%, the desorption gas content in normal atmosphere increases by 113.24%, and the determining value of gas content increases by 10.06%. The new technol- ogy has much higher accuracy, and it is worthwhile to be popularized.展开更多
Coal seam gas content is frequently measured in quantity during underground coal mining operation and coalbed methane(CBM)exploration as a significant basic parameter.Due to the calculation error of lost gas and resid...Coal seam gas content is frequently measured in quantity during underground coal mining operation and coalbed methane(CBM)exploration as a significant basic parameter.Due to the calculation error of lost gas and residual gas in the direct method,the efficiency and accuracy of the current methods are not inadequate to the large area multi-point measurement of coal seam gas content.This paper firstly deduces a simplified theoretical dynamic model for calculating lost gas based on gas dynamic diffusion theory.Secondly,the effects of various factors on gas dynamic diffusion from coal particle are experimentally studied.And sampling procedure of representative coal particle is improved.Thirdly,a new estimation method of residual gas content based on excess adsorption and competitive adsorption theory is proposed.The results showed that the maximum error of calculating the losing gas content by using the new simplified model is only 4%.Considering the influence of particle size on gas diffusion law,the particle size of the collected coal sample is below 0.25 mm,which improves the measurement speed and reflects the safety representativeness of the sample.The determination time of gas content reduced from 36 to 3 h/piece.Moreover,the absolute error is 0.15–0.50 m^3/t,and the relative error is within 5%.A new engineering method for determining the coal seam gas content is developed according to the above research.展开更多
The sudden and violent nature of coal and gas outbursts continues to pose a serious threat to coal mine safety in China. One of the key issues is to predict the occurrence of outbursts. Current methods that are used f...The sudden and violent nature of coal and gas outbursts continues to pose a serious threat to coal mine safety in China. One of the key issues is to predict the occurrence of outbursts. Current methods that are used for predicting the outbursts in China are considered to be inadequate, inappropriate or impractical in some seam conditions. In recent years, Huainan Mining Industry Group(Huainan) in China and the Commonwealth Scientific and Industrial Research Organisation(CSIRO) in Australia have been jointly developing technology based on gas content in coal seams to predict the occurrence of outbursts in Huainan. Significant progresses in the technology development have been made, including the development of a more rapid and accurate system in determining gas content in coal seams, the invention of a sampling-while-drilling unit for fast and pointed coal sampling, and the coupling of DEM and LBM codes for advanced numerical simulation of outburst initiation and propagation. These advances are described in this paper.展开更多
Gas content of coal is mostly determined using a direct method, particularly in coal mining where mine safety is of paramount importance. Direct method consists of measuring directly the volume of gas desorbed from co...Gas content of coal is mostly determined using a direct method, particularly in coal mining where mine safety is of paramount importance. Direct method consists of measuring directly the volume of gas desorbed from coal in several steps, from solid then crushed coal. In mixed gas conditions the composition of the desorbed gas is also measured to account for contribution of various coal seam gas in the mix. The determination of gas content using the direct method is associated with errors of measurement of volume of gas but also the errors associated with measurement of composition of the desorbed gas. These errors lead to uncertainties in reporting the gas content and composition of in-situ seam gas. This paper discusses the current direct method practised in Australia and potential errors and uncertainty associated with this method. Generic methods of estimate of uncertainties are also developed and are to be included in reporting gas content of coal. A method of direct measurement of remaining gas in coal following the completion of standard gas content testing is also presented. The new method would allow the determination of volume of almost all gas in coal and therefore the value of total gas content. This method is being considered to be integrated into a new standard for gas content testing.展开更多
基金funded by the Sinopec Science and Technology Project(No.P23132)the AAPG Foundation Grants-inAid Program(No.18644937)。
文摘By investigating the evolution of shale gas generation,storage,adjustment and accumulation under different structural settings in superimposed basins,this study elucidates the differential accumulation mechanisms of shale gas.An improved evaluation method of shale gas content evolution in superimposed basins is proposed.This method incorporates the coupling effect of key geological factors such as temperature,pressure,organic matter abundance,maturity,and pore characteristics on the content and occurrence state of shale gas,as well as the configuration relationship between shale gas generation and storage throughout geological history.Using this approach,the gas evolution histories of the Longmaxi Formation shales in wells N201 and PY1 are reconstructed under varying geological conditions.The Longmaxi Formation shales in these wells are dominated by typeⅠkerogen,with original total organic carbon(TOC_(o))contents of 6.20 wt% and 4.92 wt%,respectively,indicating differences in the initial material basis for gas generation.At the maximum burial depth of approximately 5000 m,the Longmaxi Formation shale in well N201 exhibits a formation pressure coefficient of 2.05,an organic matter maturity of 2.2%,and organic pores accounting for 68%of the total porosity.The gas generation quantity(Q_(g))reaches 19.24 m^(3)/t,while the gas storage capacity(Q_(s))is 4.30 m^(3)/t.The actual total gas content(Q_(a)),constrained by Q_(s),is 4.30 m^(3)/t,with free gas comprising 94%.Following relatively moderate tectonic uplift,the Q_(a) in well N201 decreases to 4.03 m^(3)/t,with free gas accounting for 63%.In contrast,the Longmaxi Formation shale in well PY1 reached a maximum burial depth of 6300 m,associated with a formation pressure coefficient of 1.62,organic matter maturity of 2.5%,and organic pore proportion of 67%.Here,Q_(g) is 16.87 m^(3)/t,and both Q_(s) and Q_(a) are 3.65 m^(3)/t,with free gas accounting for 98%.After intense tectonic uplift,Q_(a) declines to 2.72 m^(3)/t,and the proportion of free gas drops to51%.Finally,a four-stage differential accumulation model of shale gas is established:Slow gas generation and only adsorbed gas occur in stageⅠ,which is primarily controlled by TOC content;both adsorbed gas and free gas present in stageⅡ,with free gas becoming dominant;rapid gas generation and free gas predominance are controlled by temperature and porosity in stageⅢ;and gas adjustment and accumulation are primarily controlled by temperature and pressure in stageⅣ.
基金supported by the National Natural Science Foundation of China(Nos.51827901,42477191,and 52304033)the Fundamental Research Funds for the Central Universities(No.YJ202449)+1 种基金the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(No.SKLGME022009)the China Postdoctoral Science Foundation(No.2023M742446).
文摘Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks.However,existing sampling technologies face challenges in maintaining the integrity of gas content within samples and are often constrained by estimation errors inherent in empirical formulas,which results in inaccurate gas content measurements.This study introduces a lightweight,in-situ pressure-and gas-preserved corer designed to collect coal samples under the pressure conditions at the sampling point,effectively preventing gas loss during transfer and significantly improving measurement accuracy.Additionally,a gas migration model for deep coal mines was developed to elucidate gas migration characteristics under pressure-preserved coring conditions.The model offers valuable insights for optimizing coring parameters,demonstrating that both minimizing the coring hole diameter and reducing the pressure difference between the coring-point pressure and the original pore pressure can effectively improve the precision of gas content measurements.Coring tests conducted at an experimental base validated the performance of the corer and its effectiveness in sample collection.Furthermore,successful horizontal coring tests conducted in an underground coal mine roadway demonstrated that the measured gas content using pressure-preserved coring was 34%higher than that obtained through open sampling methods.
基金supported by the National Natural Science Foundation of China(42272200)The Science and Technology Major Project of China National Petroleum Corporation(2023ZZ18-03)+1 种基金The Science and Technology Major Project of Changqing Oilfeld(2023DZZ01)The Technology project of Huaneng Group Headquarters(Medium-deep Low-Rank Coalbed Methane Resource Potential Evaluation and Key Development Technologies of Zhalainuoer Coalfeld,HNKJ23-H51).
文摘Currently,regression prediction methods based on logging data is one of the main methods for analyzing gas content of coal seams.However,the complexity of logging parameters for deep coal seams and the scarcity of measured gas content data signifcantly afects the accuracy and generalizability of data regression models.Accurately predicting the gas content of coal seams under small-sample condition become a difcult point in deep coalbed methane(CBM)exploration.The ModelAgnostic Meta-Learning(MAML)and Support Vector Regression(SVR)algorithms are among the few suitable for smallsample learning,exhibiting strong adaptability under limited sample conditions.In this study,logging parameters are used as input variables to construct MAML and SVR models,and their performance in predicting gas content of deep coal seams across diferent regions and layers is compared.The results demonstrate that the MAML algorithm efectively addresses the complex relationships between gas content of deep coal seam and logging parameters.The prediction errors for test dataset and new samples are merely 3.61%and 4.52%respectively,indicating exceptional adaptability,robust generalization capability,and stable model performance.In contrast,the dependency of SVR model on input parameters restricts its accuracy and generalizability in predicting gas content in deep coal seams with varying geological conditions.Although achieving a test dataset error of 4.71%,the SVR model demonstrates substantially degraded performance when applied to novel samples,with prediction errors escalating to 12.46%.Therefore,the MAML model is selected to predict gas content in the unknown areas of the Baijiahai region.The prediction results reveal that the gas content of coal seams in the Xishanyao formation(J2x)ranges from 1.32 m^(3)/t to 16.11 m^(3)/t,while that in the Badaowan Formation(J1b)varies between 1.73 m^(3)/t and 11.27 m^(3)/t.Notably,the gas enrichment areas are predominantly distributed in well blocks adjacent to fault systems,such as wells C31 and BJ8,etc.,which align with the favorable geological conditions for deep CBM accumulation in the Baijiahai region.These spatial distribution patterns not only corroborate existing geological insights but also further validate the reliability of the MAML model in predicting gas content within deep coal seams.
基金the support of National Natural Science Foundation of China(21878019)Beijing Natural Science Foundation(2182063)。
文摘As an important form of reactors for gas/liquid/solid catalytic reaction,trickle bed reactors (TBRs) are widely applied in petroleum industry,biochemical,fine chemical and pharmaceutical industries because of their flexibility,simplicity of operation and high throughput.However,TBRs also show inefficient production and hot pots caused by non-uniform fluid distribution and incomplete wetting of the catalyst,which limit their further application in chemical industry.Also,process intensification in TBRs is necessary as the decrease in quality of processed crude oil,caused by increased exploitation depths,and more restrictive environmental regulations and emission standards for industry,caused by increased environment protection consciousness.In recent years,lots of strategies for process intensification in TBRs have been proposed to improve reaction performance to meet the current and future demands of chemical industry from the environmental and economic perspective.This article summarizes the recent progress in techniques for intensifying gas/liquid/solid reaction in TBRs and application of intensified TBRs in petroleum industry.
基金financially supported by the National Natural Science Foundation of China(52025103)。
文摘This study presents a systematic investigation of pressure drop and gas holdup in an upward-flow fixedbed reactor,examining the effects of bubble size,bed height,particle shape,superficial gas velocity(SGV),and superficial liquid velocity(SLV)based on experimental measurements and empirical correlations.Two bubble generators,namely ring tube generator(RTG)and porous sintered film generator(PSG),are used.Key findings reveal that for the PSG,increasing SGV decreases small-bubble population while promoting large-bubble formation,with the bubbles stabilizing at a Sauter mean diameter(d_(32))of~3 mm.The RTG produces stable large bubbles(d_(32)=6—7 mm)with minimal size variations across the range of tested SGVs.The pressure drop decreases with an increase in SGV but increases with higher SLV and bed height,primarily due to the reduced liquid holdup and the dominance of static pressure.Smaller bubbles reduce the pressure drop by slowing rise velocity and minimizing frictional resistance.Clover-shaped particles exhibit the highest pressure drop owing to large porosity,while 3-mm toothed spheres show higher pressure drop than 5-mm spheres at high SGV because of intensified capillary forces.The gas holdup increases with increasing SGV and bed height but decreases slightly with increasing SLV.Smaller bubbles enhance gas holdup by improving bed distribution and residence time.The 3-mm toothed spheres show the highest gas holdup due to stronger capillary trapping,whereas the clover-shaped particles exhibit the lowest.Empirical correlations for pressure drop and gas holdup are developed,yielding calculation errors within±1%and±20%of the experimental values,respectively.
基金supported by the National Natural Science Foundation of China(No.42372192)Shanxi Province science and technology plan joint unveiling project(No.20201101002)。
文摘The methane adsorption capacity,gas content,and carbon isotope characteristics of coal are crucial parameters that determine the productivity of coalbed methane(CBM)wells and their development potential.In this paper,test analyses of methane adsorption,gas content and carbon isotope of methane were carried out using 89 samples from the No.3 coal seam in the southwestern part of the Qinshui Basin.Their characteristics and correlations were analyzed.A relationship model between methane adsorption,gas content,carbon isotopes,coal metamorphism and material composition were established,and its controlling mechanism was investigated.The results indicate that the distribution patterns of Langmuir volume and Langmuir pressure in No.3 coal seam are mainly determined by the material composition and the thermal evolution level.The methane gas content in coal is mainly affected by the burial depth,microcosmic co mposition,mineral conte nt,moisture content and ash yield,adsorption capacity and metamorphism of the coal.The methane carbon isotope(δ^(13)C_(1))values in the natural desorbed gas from No.3 coal seam range from-26.95%to-57.80‰,with a mean value of-34.53‰.δ^(13)C_(1)in coal shows a two-stage variation pattern with increasing in vitrinite reflectance(R_(max)^(o)).When R_(max)^(o)is blow 3.0%,δ^(13)C_(1)values of methane in coal become progressively heavier with increasing R_(max)^(o).When R_(max)^(o)reaches or exceeds 3.0%,δ^(13)C_(1)values exhibit a lightning trend with furth er increases in R_(max)^(o),which is primarily controlled by the carbon isotope fractionation effects during thermal evolution.
基金supported by the project 2024J01421supported by Fujian Provincial Natural Science Foundation.
文摘Bubble column reactors fitted with tube bundles(BCR TB)belong to common heat transfer equipment in the field of chemical engineering,yet the complicated thermal-hydraulics performance of BCR TB has not been deeply revealed.To fill this gap,the present study proposes a novel variable bubble size modeling approach based on the Euler-Euler two-fluid framework,which is coupled with the population balance model considering comprehensive interphase forces.On the basis of verifying numerical reliability using experimental data,the mechanism of bubble swarm flow around the tube bundle and the effects of gas sparger configurations on the thermal-hydraulics performance of BCR TB are investigated.Results indicate that the entire tube bundle can be divided into three distinct zones,namely the sparger effect zone,fully developed zone and interface effect zone in view of the local mixture-to-wall heat transfer coefficient.The maximum peak value of the mixture-to-wall heat transfer coefficient always appears at 210°of heat exchange tubes.When the orifice diameter is 4 mm,the axial gradient of gas holdup is relatively large due to more intense shearing and fragmentation effects.Interestingly,the fractions of medium-sized and large-sized bubbles are not sensitive to orifice angle.Both the mixture-to-wall heat transfer coefficient and the friction factor decrease initially and then increase when the installation height increases.Under the optimized gas sparger structure configuration,the mixture-to-wall heat transfer coefficient increases by 10.23%,accompanied by the reduction of pressure drop by 8.14%,ultimately attaining a system energy conversion efficiency of 97.88%and performance evaluation criterion of 1.087.Finally,a new dimensionless and semi-theoretical Nusselt correlation incorporating a structural correction factor with an average absolute deviation of 5.15%is developed.The findings can offer useful guidance for the optimal design of BCR TB.
基金supported by the National Natural Science Foundation of China(41925014).
文摘The Lower Cambrian shales in the Sichuan Basin are considered one of the most promising shale gas resources in China.However,large-scale commercial development has not been achieved due to the relatively low and significantly variable gas contents of the drilled shales.Excitingly,the first major breakthrough in deep and ultra-deep Lower Cambrian shale gas was made recently in the well Z201 in the southern Sichuan Basin,with a gas yield exceeding 73×10^(4)m^(3)/d.The success of well Z201 provides a favorable geological case to reveal the distinct enrichment mechanism of deep and ultra-deep Lower Cambrian shale gas.In this study,at drilling site of well Z201,fresh shale core samples with different gasin-place contents were collected,and their geochemical,pore development and water-bearing characteristics were analyzed systematically.The results showed that the Z201 organic-rich shales reached an overmature stage,with an average Raman maturity of 3.70%.The Z201 shales with high gas-in-place contents are mainly located in the Qiongzhusi 12section and the upper Qiongzhusi 11section,with an average gas-in-place content of 10.08 cm^(3)/g.Compared to the shales with low gas-in-place contents,the shales with high gas-in-place contents exhibit higher total organic carbon contents,greater porosities,and lower water saturations,providing more effective pore spaces for shale gas enrichment.The effective pore structures of the deep and ultra-deep Lower Cambrian shales are the primary factors affecting their gas-in-place contents.Similar to the shales with high gas-in-place contents of well Z201,the deep and ultra-deep Lower Cambrian shales in the Mianyang-Changning intracratonic sag,especially in the Ziyang area,generally developed in deep-water shelf facies with high total organic carbon contents and thick sedimentary thickness,providing favorable conditions for the development and preservation of effective pores.Therefore,they are the most promising targets for Lower Cambrian shale gas exploration.
基金The project supported by the Nuclear Researchers Exchange Program of Japan Society for the Promotion of Science
文摘High-pressure gas injection has proved to be an effective disruption mitigation tech- nique in DIII-D tokamak experiments. If the method can be applied in future tokamak reactors not only for disruption mitigation but also for plasma termination and fueling, it will have an attractive advantage over the pellet and liquid injection from the viewpoint of economy and engineering design. In order to investigate the feasibility of this option, a study has been carried out with relevant parameters for conveying tubes of different geometrical sizes and for different gases. These parameters include pressure drop, lagger time after the valve＇s opening, gas diffusion in an ultra-high vacuum condition, and particle number contour.
基金Funded by the Natural Science Fundation of China for Creative Research Groups (No. 50621403)the Visiting Scholar Foundation of Key Lab. of University Projects (KLVF-2006-5).
文摘Increasingly high requirement driven by environmental concern leads to more rigorous standards for sulfur dosage in fuel. Natural gas desulfurization is an important unit for industrial natural gas process. Catalytic membrane reactor for sulfur compounds removal is a newly emerged and integrated membrane technology. We reviewed the current progress for desulfurization of natural gas with membrane process, and predicted that the process combined with catalytic membrane reactor and microwave irradiation for desulfurization of natural gas might be an integrated and promising unit for large scale desulfurization with high efficiency.
基金Supported by the China National Science and Technology Major Project on New-Type Oil and Gas Exploration and Development(2025ZD1404200,2025ZD1400800)PetroChina Science and Technology Project(2023ZZ07)。
文摘Based on the data of regional geology,seismic,drilling,logging and production performance obtained from 94 major petroliferous basins worldwide,the global coal resources were screened and statistically analyzed.Then,using established definition methods and evaluation criteria for coal-rock gas in China,and by analogy with the tectono-sedimentary and burial-thermal evolution conditions of coal rocks in sedimentary basins within China,the geological resource potential of global coal-rock gas was estimated mainly by the volume method,partly by the volumetric method in selected regions.According to the evaluation indicator system comprising 14 parameters under 5 categories and the associated scoring criteria,the target basins were ranked,and the future research targets for these basins were proposed.The results reveal that,globally,coal rocks are primarily formed in four types of swamp environments within four categories of prototype basins,and distributed across five major coal-forming periods and eight coal-accumulation belts.The total geological coal resources are estimated at approximately 42×10^(12)t,including 22×10^(12)t in the strata deeper than 1500 m.The global geological coal-rock gas resources in deep strata are roughly 232×10^(12)m^(3),of which over 90%are endowed in Russia,Canada,the United States,China and Australia,with China contributing 24%.The top 10 basins by coal-rock gas resource endowment,i.e.Alberta,Kuznetsk,Ordos,East Siberian,Bowen,West Siberian,Sichuan,South Turgay,Lena-Vilyuy and Tarim,collectively hold 75%of the global total.The Permian,Cretaceous,Carboniferous,Jurassic,and Paleogene-Neogene account for 32%,30%,18%,10%,and 7%of total coal-rock gas resources,respectively.The 10 most practical basins for future coal-rock gas exploration and development are identified as Alberta,Ordos,Kuznetsk,San Juan,Sichuan,East Siberian,Rocky Mountain,Bowen,Junggar and Qinshui.Propelled by successful development practices in China,coal-rock gas is now entering a phase of theoretical breakthrough,technological innovation,and rapid production growth,positioning it to spearhead the next wave of the global unconventional oil and gas revolution.
基金partially funded by Shenzhen Science and Technology Program(No.JCYJ20240813112038050)the National Natural Science Foundation of China(No.52404059)+1 种基金the Economy Trade and Information Commission of Shenzhen Municipality,China(No.HYCYPT20140507010002)the Key Program of Marine Economy Development(Six Marine Industries)Special Foundation of the Department of Natural Resources of Guangdong Province,China(No.GDOE[2021]55).
文摘Natural gas hydrate in Class Ⅰ reservoirs holds significant commercial potential,as demonstrated by production trials in the South China Sea.However,experimental studies have focused largely on Class Ⅲ systems,with Class Ⅰ/Ⅱ reservoirs remaining underrepresented due to the difficulties in simulating the geothermal gradient and interlayer interactions.This study investigates depressurization performance across all three classes using a novel 360°rotatable reactor with segmented temperature control,enabling precise simulation of reservoir conditions.Results reveal:(i)Class Ⅰ shows two-stage gas production,with 50%from early free gas enabling rapid depressurization,followed by dissociated gas dominance.They achieve 38.4%-78.3%higher cumulative production and superior gas-to-water ratios due to efficient energy use.(ii)The free gas layer in Class Ⅰ accelerates pressure and heat transfer.Class Ⅱ’s water layer provides sensible heat but causes water blocking,impairing heat flow.Class Ⅲ exhibits rapid initial dissociation but a quick decline without fluid support.(iii)Low temperature,low hydrate saturation,and high production pressure collectively reduce efficiency by increasing flow resistance,limiting gas supply,and reducing dissociation drive.Over-depressurization risks hydrate reformation and ice blockage.This work bridges experimental gaps for Class Ⅰ/Ⅱ reservoirs,offering key insights for optimizing recovery.
基金Supported by Guangxi Key Research and Development Program Project(GuiKe AB18221095)Open Fund Project of Guangxi Key Laboratory of Research on Ethnic Medicinal Plants in the Youjiang River Basin(yykf2024-01)+1 种基金High-level Talent Research Project of Youjiang Medical University for Nationalities(1002018079)2023 National-level College Student Innovation and Entrepreneurship Training Program Project(202310599008).
文摘[Objectives]To determine the content of Zhuang medicine Sauropus spatulifolius Beille from Guangxi.[Methods]The amino acid content of S.spatulifolius Beille was determined by ultraviolet spectrophotometry(UVs).The content of kaempferol-3-O-gentiobioside in S.spatulifolius Beille was determined by liquid chromatography-mass spectrometry(LC-MS).Pesticide residues in S.spatulifolius Beille were detected by gas chromatography-mass spectrometry(GC-MS).Heavy metal elements arsenic(As),cadmium(Cd),and lead(Pb)in S.spatulifolius Beille were detected by inductively coupled plasma mass spectrometry(ICP-MS).[Results]The amino acid content in S.spatulifolius Beille was 3.233 mg/g,with a relative standard deviation(RSD)of 0.36%.The content of kaempferol-3-O-gentiobioside was 1.15μg/mL.No pesticide residues or heavy metals were detected in the S.spatulifolius Beille medicinal material.[Conclusions]This study improves the quality control system for S.spatulifolius Beille and provides a reference basis for the quality standard control of Zhuang medicine S.spatulifolius Beille from Guangxi.
基金Project(2010CB630904) supported by the National Basic Research Program of ChinaProject(5102030) supported by the Beijing Natural Science Foundation,China+1 种基金Projects(21076214,21006108) supported by the National Natural Science Foundation of ChinaProject supported by the Open Funding Project of the State Key Laboratory of Bioreactor Engineering,China
文摘Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioactivity of At.ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al2O3 powder,but the biooxidation rate of Fe2＋ decreases markedly from 0.23 g/（L·h） to 0.025 g/（L·h） with increasing the content of Al2O3 powder from 0 to 50%（mass fraction） in the stirred-tank probably due to the deactivation of At.ferrooxidans resulting from the collision and friction of solid particles.The increase in Al2O3 content has a little adverse effect on the bioactivity of At.ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors.The biooxidation rate of Fe2＋ in the rotating-drum is higher than that in the stirred-tank at the same content of Al2O3 powder,especially at high solid content.The higher bioactivity of At.ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor,but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al2O3 powder and sulfide minerals.
文摘Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality.Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit(ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit(MCF) method, based on the 'bidisperse' diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation(USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, the ACF and MCF methods, are the best options respectively.
基金financially supported by the Natural Science Foundation of China (NSFC Grant 41572106)+1 种基金the National Science and Technology Major Project "The enrichment conditions, evaluation technology and application of shale gas in the Sichuan Basin and its periphery" (Item No. 2017ZX05035002-006)State Key Laboratory of oil and gas resources and exploration, Chinese University of Petroleum-Beijing
文摘Comprehensive quantitative evaluation of shale gas content and the controlling factors in different occurrence states is of great significance for accurately assessing gas-bearing capacity and providing effective well-production strategies. A total of 122 core samples from well JY-A in the Fuling shale gas field were studied to reveal the characteristics of S_1 l shale,15 of which were selected to further predict the shale gas content in different occurrence states, which are dependent on geological factors in the thermal evolution process. Geological parameters were researched by a number of laboratory programs, and the factors influential in controlling shale gas content were extracted by both PCA and GRA methods and prediction models were confirmed by the BE method using SPSS software. Results reveal that the adsorbed gas content is mainly controlled by TOC, Ro, SSA, PD and pyrite content, and the free gas content is mainly controlled by S_2, quartz content, gas saturation and formation pressure for S_1 l in well JY-A. Three methods, including the on-site gas desorption method, the empirical formula method, and the multiple regression analysis method were used in combination to evaluate the shale gas capacity of well JY-A, all of which show that the overall shale gas content of well JY-A is in the range of 2.0–5.0 m^3/t and that the free gas ratio is about 50%, lower than that of well JY-1. Cause analysis further confirms the tectonics and preservation conditions of S_1 l in the geological processes, especially the influence of eastern boundary faults on well JY-A, as the fundamental reasons for the differences in shale gas enrichment in the Jiaoshiba area.
文摘The key of the direct method of determining coalbed gas content is how to shorten the coal core exposure time in the sampling progress and reduce measuring error of gas content which comes from the calculation of losing gas content. The coring tests were carried out in No.24 drilling field of 715 floor gateway in Qinan Coal Mine by using traditional drill core bar- rel sampler and self-designed reversion seal coring equipment. The losing gas content was calculated by power functional method, and the gas content of two coring methods was determined, respectively. Results show that, compared with traditional drill core barrel sampling, the newly seal coring equipment can significantly shorten the coal core exposure time, the 30 min desorption gas content increases obviously, the calculation of losing gas content reduces by 56.99%, the desorption gas content in normal atmosphere increases by 113.24%, and the determining value of gas content increases by 10.06%. The new technol- ogy has much higher accuracy, and it is worthwhile to be popularized.
基金the National Natural Science Foundation of China(51774119,51374095,and 51604092)the primary research projects of critical scientific research in Henan Colleges and Universities(19zx003)+1 种基金Program for Innovative Research Team in University of Ministry of Education of China(IRT_16R22)State Key Laboratory Cultivation Base for Gas Geology and Gas Control(Henan Polytechnic University)(WS2018A02)。
文摘Coal seam gas content is frequently measured in quantity during underground coal mining operation and coalbed methane(CBM)exploration as a significant basic parameter.Due to the calculation error of lost gas and residual gas in the direct method,the efficiency and accuracy of the current methods are not inadequate to the large area multi-point measurement of coal seam gas content.This paper firstly deduces a simplified theoretical dynamic model for calculating lost gas based on gas dynamic diffusion theory.Secondly,the effects of various factors on gas dynamic diffusion from coal particle are experimentally studied.And sampling procedure of representative coal particle is improved.Thirdly,a new estimation method of residual gas content based on excess adsorption and competitive adsorption theory is proposed.The results showed that the maximum error of calculating the losing gas content by using the new simplified model is only 4%.Considering the influence of particle size on gas diffusion law,the particle size of the collected coal sample is below 0.25 mm,which improves the measurement speed and reflects the safety representativeness of the sample.The determination time of gas content reduced from 36 to 3 h/piece.Moreover,the absolute error is 0.15–0.50 m^3/t,and the relative error is within 5%.A new engineering method for determining the coal seam gas content is developed according to the above research.
文摘The sudden and violent nature of coal and gas outbursts continues to pose a serious threat to coal mine safety in China. One of the key issues is to predict the occurrence of outbursts. Current methods that are used for predicting the outbursts in China are considered to be inadequate, inappropriate or impractical in some seam conditions. In recent years, Huainan Mining Industry Group(Huainan) in China and the Commonwealth Scientific and Industrial Research Organisation(CSIRO) in Australia have been jointly developing technology based on gas content in coal seams to predict the occurrence of outbursts in Huainan. Significant progresses in the technology development have been made, including the development of a more rapid and accurate system in determining gas content in coal seams, the invention of a sampling-while-drilling unit for fast and pointed coal sampling, and the coupling of DEM and LBM codes for advanced numerical simulation of outburst initiation and propagation. These advances are described in this paper.
文摘Gas content of coal is mostly determined using a direct method, particularly in coal mining where mine safety is of paramount importance. Direct method consists of measuring directly the volume of gas desorbed from coal in several steps, from solid then crushed coal. In mixed gas conditions the composition of the desorbed gas is also measured to account for contribution of various coal seam gas in the mix. The determination of gas content using the direct method is associated with errors of measurement of volume of gas but also the errors associated with measurement of composition of the desorbed gas. These errors lead to uncertainties in reporting the gas content and composition of in-situ seam gas. This paper discusses the current direct method practised in Australia and potential errors and uncertainty associated with this method. Generic methods of estimate of uncertainties are also developed and are to be included in reporting gas content of coal. A method of direct measurement of remaining gas in coal following the completion of standard gas content testing is also presented. The new method would allow the determination of volume of almost all gas in coal and therefore the value of total gas content. This method is being considered to be integrated into a new standard for gas content testing.
