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1.
为了更精确描述煤层气注气开发或二氧化碳煤层封存涉及到的多组分吸附过程,采用扩展Langmuir、理想吸附溶剂和二维状态方程预测不同煤对甲烷-二氧化碳混合气体的吸附,并将三种模型预测结果与实验数据进行对比分析,结果表明:二维状态方程模型对混合气体的吸附预测精度最高,并且能较好适用于高压系统的吸附预测。除此之外,从三种模型分离因子的变化规律可以看出,理想吸附溶剂和二维状态方程模型在吸附时都考虑了气体相对吸附性随平衡气相组分和压力的变化,而扩展Langmuir没有考虑该因素。因此,也表明理想吸附溶剂和二维状态方程模型在预测多组分气体相对吸附方面具有一定的优势。 相似文献
2.
Frank van Bergen Chris Spiers Geerke Floor Pieter Bots 《International Journal of Coal Geology》2009,77(1-2):43-53
Field experiments and laboratory studies have shown that swelling of coal takes place upon contact with carbon dioxide at underground pressure and temperature conditions. Understanding this swelling behavior is crucial for predicting the performance of future carbon dioxide sequestration operations in unminable coal seams conducted in association with methane production. Swelling is believed to be related to adsorption on the internal coal surface. Whereas it is well established that moisture influences the sorption capacity of coal, the influence of water on coal swelling is less well-defined. This paper presents the results of laboratory experiments to investigate the effect of moisture on coal swelling in the presence of carbon dioxide, methane and argon. Strain development of an unconfined sample of about 1.0–1.5 mm3 at 40 °C and 8 MPa (and at other pressures) was observed in an optical cell under a microscope as a function of time. Both air dried and moisturized samples were used. Results confirmed different swelling behaviors of coal with different substances: carbon dioxide leads to higher strain than methane, while exposure to argon leads to very little swelling. The experiments on moisturized samples seem to confirm the role of moisture as a competitor to gas molecules for adsorption sites. Adsorption of water could also explain the observed swelling due to water uptake at atmospheric pressure. A re-introduction of carbon dioxide, after intermediate gas release, results in higher strains which indicate a drying effect of the carbon dioxide on the coal. The results of this study show that the role of water cannot be ignored if one wants to understand the fundamental processes that are taking place in enhanced coalbed methane operations. 相似文献
3.
Maria Mastalerz Wilfrido Solano-Acosta Arndt Schimmelmann Agnieszka Drobniak 《International Journal of Coal Geology》2009,79(4):167-174
This paper investigates changes in the high-volatile bituminous Lower Block Coal Member from Indiana owing to moisture availability and oxidation in air at ambient pressure and temperature over storage time. Specifically, it investigates changes in chemistry, in surface area, and pore structure, as well as changes in methane and carbon dioxide adsorption capacities. Our results document that the methane adsorption capacity increased by 40%, whereas CO2 adsorption capacity increased by 18% during a 13-month time period. These changes in adsorption are accompanied by changes in chemistry and surface area of the coal.The observed changes in adsorption capacity indicate that special care must be taken when collecting samples and preserving coals until adsorption characteristics are measured in the laboratory. High-pressure isotherms from partially dried coal samples would likely cause overestimation of gas adsorption capacities, lead to a miscalculation of coal-bed methane prospects, and provide deceptively optimistic prognoses for recovery of coal-bed methane or capture of anthropogenic CO2. 相似文献
4.
L.D. Connell R. SanderZ. Pan M. CamilleriD. Heryanto 《International Journal of Coal Geology》2011,87(2):128-138
Enhanced coalbed methane (ECBM) involves the injection of a gas, such as nitrogen or carbon dioxide, into the coal reservoir to displace the methane present. Potentially this strategy can offer greater recovery of the coal seam methane and higher rates of recovery due to pressure maintenance of the reservoir. While reservoir simulation forms an important part of the planning and assessment of ECBM, a key question is the accuracy of existing approaches to characterising and representing the gas migration process. Laboratory core flooding allows the gas displacement process to be investigated on intact coal core samples under conditions analogous to those in the reservoir. In this paper a series of enhanced drainage core floods are presented and history matched using an established coal seam gas reservoir simulator, SIMED II. The core floods were performed at two pore pressures, 2 MPa and 10 MPa, and involve either nitrogen or flue gas (90% nitrogen and 10% CO2) flooding of core samples initially saturated with methane. At the end of the nitrogen floods the core flood was reversed by flooding with methane to investigate the potential for hysteresis in the gas displacement process. Prior to the core flooding an independent characterisation programme was performed on the core sample where the adsorption isotherm, swelling with gas adsorption, cleat compressibility and geomechanical properties were measured. This information was used in the history matching of the core floods; the properties adjusted in the history matching were related to the affect of sorption strain on coal permeability and the transfer of gas between cleat and matrix. Excellent agreement was obtained between simulated and observed gas rates, breakthrough times and total mass balances for the nitrogen/methane floods. It was found that a triple porosity model improved the agreement with observed gas migration over the standard dual porosity Warren-Root model. The Connell, Lu and Pan hydrostatic permeability model was used in the simulations and improved history match results by representing the contrast between pore and bulk sorption strains for the 10 MPa cases but this effect was not apparent for the 2 MPa cases. There were significant differences between the simulations and observations for CO2 flow rates and mass balances for the flue gas core floods. A possible explanation for these results could be that there may be inaccuracy in the representation of mixed gas adsorption using the extended Langmuir adsorption model. 相似文献
5.
为了研究不同煤级煤对H2S气体的吸附差异及吸附模型,采集新疆气煤,山西潞安瘦煤、晋城无烟煤3个煤样进行了工业分析、煤岩分析和平衡水条件下的等温吸附实验。采用Langmuir,BET,D-R和D-A吸附模型,利用拟合软件对等温吸附实验数据进行了非线性回归拟合,并检验拟合程度。结果表明:煤对H2S的吸附量随着煤化程度的加深而增加,为第Ⅰ类等温吸附线;其中Langmuir模型的拟合效果最好,n=1的D-A模型的拟合效果次之,BET模型的拟合效果较差,模型对实验数据的拟合效果与吸附模型中参数个数无明显关系;煤吸附H2S可用单分子层吸附理论来解释。 相似文献
6.
页岩中气体的超临界等温吸附研究 总被引：1，自引：0，他引：1
页岩气等温吸附实验多为临界温度以上的吸附实验,其得到的吸附量为过剩吸附量。为了研究页岩气超临界等温吸附机理,运用重力法,在临界温度以上,分别进行了甲烷和二氧化碳在页岩中的高压等温吸附实验。在分析经典型吸附和超临界吸附区别的基础上,通过修改的超临界等温吸附模型(Langmuir方程和微孔充填(Dubinin Radushkevich,D-R))对实验数据进行了拟合。结果表明:简单的Langmuir方程可近似拟合甲烷吸附实验数据,但精度不高,且无法拟合二氧化碳的吸附数据;将吸附相密度作为可优化参数,修改的微孔充填模型和Langmuir模型能很好地拟合甲烷和二氧化碳的吸附数据,其中修改的微孔充填模型拟合效果最好,且回归得到的超临界甲烷吸附相密度同文献报道的一致,表明吸附气可能以微孔充填的形式存在。 相似文献
7.
M. Salmasi S. Fatemi M. Doroudian Rad F. Jadidi 《International Journal of Environmental Science and Technology》2013,10(5):1067-1074
Carbon dioxide is known as a hazardous material with acidic property that can be found as impurity in natural gas reservoirs with a broad range of 2 up to 40 %. Therefore, many efforts have been directed to remove and separate carbon dioxide from methane to prevent corrosion problems as well as improving the natural gas energy content. In this study, two molecular sieves, silicoaluminophosphate-34 (SAPO-34) zeotype and T-type zeolite, were synthesized by the hydrothermal method for the comparative study of adsorptive separation of carbon dioxide from methane. The synthesized adsorbents were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Brunner–Emmett–Teller techniques. These characterization tests confirmed formation of both materials with acceptable crystallinity. Both adsorbents were tested in equilibrium adsorption experiments in order to evaluate maximum capacity and adsorption affinity. Adsorption capacity of carbon dioxide and methane on SAPO-34 and zeolite T were measured in a pressure range of 0.1–2.0 MPa and temperature of 288, 298, and 308 K and fitted with the Sips and Langmuir isotherm models. The ideal selectivity of CO2/CH4 was determined for SAPO-34 and zeolite T at the studied pressures and temperatures, indicating that the molecular sieves can be properly used for CO2–CH4 separation or CO2 capturing from natural gas. 相似文献
8.
Apiradee Terdputtakun Orn-anong Arqueropanyo Ponlayuth Sooksamiti Sorapong Janhom Wimol Naksata 《Environmental Earth Sciences》2017,76(22):777
Leonardite, a by-product from coal mines, was applied to adsorb Cd(II) and Zn(II) from aqueous solutions. Individual and simultaneous adsorptions of the two metal ions were investigated. In a single-component adsorption system, Langmuir and Freundlich isotherms were fitted to the adsorption data. Linear and nonlinear regression methods were used for the assessment of the optimum adsorption isotherm. Error functions including root-mean-square error, sum of the squares of the errors, mean absolute percentage error, Marquardt’s percent standard deviation (MPSD), and Chi-square were applied in the nonlinear regression. The most suitable model for the adsorption of Cd(II) and Zn(II) in the single system is the Freundlich isotherm. The isotherm parameters calculated by MPSD provided the lowest sum of normalized error (SNE) value. The adsorption capacity was found to be 23.89 mg/g for Cd(II) and 16.86 mg/g for Zn(II). It was observed that the adsorption of Cd(II) on leonardite is greater than that of Zn(II). For binary component adsorption systems, Cd(II) and Zn(II) showed antagonistic behavior. The presence of the other metal ions could decrease the amount of metal adsorbed. Binary adsorption of Cd(II) and Zn(II) was tested with regard to four multi-component isotherms: Extended Langmuir, Modified Langmuir, Sheindorf–Rebuhn–Sheintuch, and Extended Freundlich. The Extended Freundlich isotherm proved to be a good fit for the experimental data. 相似文献
9.
CUI Yongjun ZHANG Dengfeng ZHANG Qun LIN Weigang SONG Wenli LI Yuhui JIANG Wenping 《《地质学报》英文版》2010,84(6):1547-1554
<正>Four coal samples of different ranks are selected to perform the adsorption measurement of high-pressure methane(CH4).The highest equilibrium pressure of the measurement exceeds 20 MPa. Combined with the measuring results and theoretical analyses,the reasons for the peak or the maximum adsorption capacity appearing in the excess adsorption isotherms are explained.The rules of the peak occurrence are summarized.And then,based on the features of coal pore structure,the adsorption features of high-pressure gas,the microcosmic interaction relationship of coal surface and CH4 molecule,and the coalbed methane reservoir conditions,three theoretical assumptions on the coal adsorption high-pressure CH_4 are suggested.Thereafter,on the basis of these theoretical assumptions,the Ono-Kondo lattice model is processed for simplification and deformation. Subsequently,the equations modeling the excess adsorption isotherm of high-pressure CH_4 adsorption on coal are obtained.Through the verification on the measurement data,the fitting results indicate that it is feasible to use the Ono-Kondo lattice mode to model the excess adsorption isotherm of high-pressure CH_4 adsorption on coal. 相似文献
10.
甲烷在煤基质中的扩散性能是影响煤层气产出的重要储层参数。采用云南东南部地区新近系中新统小龙潭组褐煤样品,开展了低煤阶煤中甲烷等温吸附实验。基于等温吸附实验获得的吸附量与时间的关系数据,应用一元孔隙结构气体非稳态扩散模型,计算了煤中甲烷气体扩散系数,揭示了煤中甲烷扩散规律和控制机理。研究结果表明,低煤阶煤中气体扩散规律服从Langmuir方程,煤中甲烷有效扩散系数和扩散系数随着压力的增高而增大;吸附时间常数随着压力的增高而减小,服从负指数函数规律。4个实验煤样Langmuir有效扩散系数和扩散系数分别是（1.71~5.46）×10-4 s-1和（2.17~6.91）×10-12 m2/s,Langmuir压力为0.63~1.97 MPa。在相同温度和压力条件下,干燥煤样的有效扩散系数和扩散系数大于平衡水分煤样,随着温度的增高,其有效扩散系数和扩散系数增加,煤中气体扩散性能增强。 相似文献
11.
煤层瓦斯含量计算方法探讨 总被引：7，自引：0，他引：7
煤层瓦斯含量作为煤层瓦斯摹本参数之一，准确测定有重要意义：目前常用的煤层瓦斯含量计算方法是根据已知的煤层瓦斯压力和实验室测出煤样干燥无灰基的吸附常数计算，需水分、灰分系数校正，在实践中我们采用煤样空气干燥基的langmuir体积和langmuir压力来计算煤层吸附瓦斯含量，获得了更为简化适用的公式。 相似文献
12.
注入CO2提高煤层气产能的可行性研究 总被引：15，自引：0，他引：15
根据煤储层吸附一解吸机理,首次采用“解吸一注气一解吸”的实验方法,分别进行CH4,CO2的吸附一解吸和CO2注入置换煤层CH4实验,模拟了煤层气井“排采一注气一排采”的增产途径和效果。结果表明：在CH4和CO2二元体系的竞争吸附中,CO2组分的吸附速率是先快后慢,而CH4组分的吸附速率先慢后快,解吸时则相反,反映出CO2在竞争吸附中占据优势;注入CO2气体的数量越大和相对浓度越高,单位压降CH4解吸率和CO2吸附率就越高。实验结论对工业规模的煤层气开发试验具有指导意义。 相似文献
13.
14.
The coal seams of Sawang Colliery, East Bokaro Coalfields are bituminous to sub-bituminous in nature and categorized as high
gaseous seams (degree II to degree III level). These seams have the potential for coal bed methane (CBM) and their maturity
increases with increasing depth, as a result of enhanced pressure-temperature conditions in the underground. The vitrinite
maceral group composition of the investigated coal seams ranges from 62.50–83.15%, whereas the inertinite content varies from
14.93–36.81%. The liptinite content varies from 0.66% to 3.09%. The maximum micro-pores are confined within the vitrinite
group of macerals. The coal seams exhibit vitrinite reflectance values (Ro% calculated) from 0.94% (sample CG-97) to 1.21%
(sample CG-119).
Proximate analyses of the investigated coal samples reveal that the moisture content (M%) ranges from 1.28% to 2.98%, whereas, volatile matter (VM%) content is placed in the range of 27.01% to 33.86%. The ash
content (A%) ranges from 10.92% to 30.01%. Fixed carbon (FC%) content varies from 41.53% to 55.93%. Fuel ratio variation shows a restricted
range from 1.53 to 1.97. All the coal samples were found to be strongly caking and forming coke buttons.
The present study is based on the adsorption isotherm experiments carried out under controlled P-T conditions for determination of actual gas adsorption capacity of the coal seams. This analysis shows that the maximum methane
gas adsorbed in the coal sample CG-81 is 17 m3/t (Std. daf), at maximum pressure of 5.92 MPa and experimental temperature of 30°C. The calculated Langmuir regression parameters
PL and VL range from 2.49 to 3.75 MPa and 22.94 to 26.88 m3/t (Std. daf), respectively. 相似文献
15.
A theoretical model for gas adsorption-induced coal swelling 总被引：6，自引：2，他引：6
Swelling and shrinkage (volumetric change) of coal during adsorption and desorption of gas is a well-known phenomenon. For coalbed methane recovery and carbon sequestration in deep, unminable coal beds, adsorption-induced coal volumetric change may cause significant reservoir permeability change. In this work, a theoretical model is derived to describe adsorption-induced coal swelling at adsorption and strain equilibrium. This model applies an energy balance approach, which assumes that the surface energy change caused by adsorption is equal to the elastic energy change of the coal solid. The elastic modulus of the coal, gas adsorption isotherm, and other measurable parameters, including coal density and porosity, are required in this model. Results from the model agree well with experimental observations of swelling. It is shown that the model is able to describe the differences in swelling behaviour with respect to gas species and at very high gas pressures, where the coal swelling ratio reaches a maximum then decreases. Furthermore, this model can be used to describe mixed-gas adsorption induced-coal swelling, and can thus be applied to CO2-enhanced coalbed methane recovery. 相似文献
16.
Coal swelling/shrinkage during gas adsorption/desorption is a well-known phenomenon. For some coals the swelling/shrinkage shows strong anisotropy, with more swelling in the direction perpendicular to the bedding than that parallel to the bedding. Experimental measurements performed in this work on an Australian coal found strong anisotropic swelling behaviour in gases including nitrogen, methane and carbon dioxide, with swelling in the direction perpendicular to the bedding almost double that parallel to the bedding. It is proposed here that this anisotropy is caused by anisotropy in the coal's mechanical properties and matrix structure. The Pan and Connell coal swelling model, which applies an energy balance approach where the surface energy change caused by adsorption is equal to the elastic energy change of the coal solid, is further developed to describe the anisotropic swelling behaviour incorporating coal property and structure anisotropy. The developed anisotropic swelling model is able to accurately describe the experimental data mentioned above, with one set of parameters to describe the coal's properties and matrix structure and three gas adsorption isotherms. This developed model is also applied to describe anisotropic swelling measurements from the literature where the model was found to provide excellent agreement with the measurement. The anisotropic coal swelling model is also applied to an anisotropic permeability model to describe permeability behaviour for primary and enhanced coalbed methane recovery. It was found that the permeability calculation applying anisotropic coal swelling differs significantly to the permeability calculated using isotropic volumetric coal swelling strain. This demonstrates that for coals with strong anisotropic swelling, anisotropic swelling and permeability models should be applied to more accurately describe coal permeability behaviour for both primary and enhanced coalbed methane recovery processes. 相似文献
17.
为揭示在温度、地应力和瓦斯压力等多场作用下煤与瓦斯（methane）相互作用对煤矿瓦斯抽采、CO2注气强化瓦斯开采及CO2在深部不可采煤层的封存具有的重要意义,更精确地从微观角度观测在多物理场耦合条件下煤瓦斯相互作用的动态过程,研制了一种在多场耦合条件下带显微观测装置的煤瓦斯试验装置。该装置由密封容器与施力夹持机构、气压系统、温度场系统、显微观测系统4部分组成,能够通过显微观测装置结合图像处理技术,直接观测多场条件下煤与不同气体的相互作用所引起的细微变化。利用该装置进行了无应力加载、相同温度、相同气压下的瓦斯、CO2的吸附膨胀试验。研究发现,（1）试件在两种气体的变形大致经历了快速增长、缓慢增长直至平衡3个阶段,类似于吸附等温曲线;（2）试件在CO2气体中达到吸附饱和的时间比试件在瓦斯气体中达到吸附饱和的时间要短;（3）试件在瓦斯气体中的最大线性应变约为0.15%,相同条件下试件在CO2气体中的最大线应变约为0.5%,相同条件下试件在CO2气体中达到吸附饱和时的最大应变比试件在瓦斯气体中达到吸附饱和时的最大应变大3倍左右。研制的装置具有结构简单、直观、精度高的特点。 相似文献
18.
根据达西渗流理论 ,结合Langmuir等温吸附定律和Fick第一定律描述了煤层气由煤基质解吸经扩散进入煤层裂隙系统 ,由裂隙运移至生产井筒产出的气水二相渗流过程 ,又将其和由渗流作用引起的煤体变形场耦合起来 ,形成了煤层气运移产出的气水固三相耦合模型 ,并采用全隐式联立求解方法同时隐式求出了气、水产量和饱和度值 ,实现了模型求解的无条件稳定。在沁水盆地 3 # 煤层气井开采潜能的评价预测中 ,应用该方法分别预测了将该井的动液面置于 3 # 煤底和 15 # 煤底的气、水产量 ,效果良好。 相似文献
19.
Hongguan Yu Weijia Guo Jiulong Cheng Qianting Hu 《International Journal of Coal Geology》2008,74(3-4):250-258
Modelling the sorption properties of coals for carbon dioxide under supercritical conditions is necessary for accurate prediction of the sequestering ability of coals in seams. We present recent data for sorption curves of three dry Argonne Premium coals, for carbon dioxide, methane and nitrogen at two different temperatures at pressures up to 15 MPa. The sorption capacity of coals tends to decrease with increasing temperature. An investigation into literature values for sorption of nitrogen and methane by charcoal also show sorption capacities that decrease dramatically with increasing temperature. This is inconsistent with expectations from Langmuir models of coal sorption, which predict a sorption capacity that is independent of temperature. We have successfully fitted the isotherms using a modified Dubinin–Radushkevich equation that uses gas density rather than pressure. A simple pore-filling model that assumes there is a maximum pore width that can be filled in supercritical conditions and that this maximum pore width decreases with increasing temperature, can explain this temperature dependence of sorption capacity. It can also explain why different supercritical gases give apparently different surface sorption capacities on the same material. The calculated heat of sorption for these gases on these coals is similar to those found for these gases on activated carbon. 相似文献
20.
针对目前页岩吸附等温线测试温度、压力通常未达到储层温压条件这一问题,设计了页岩高温高压吸附等温线测试方法,研究了储层温度、压力条件下页岩吸附等温线特征,以实际页岩岩心为例计算了游离气和吸附气随压力的变化规律,并采用全直径页岩氦气和甲烷控压生产实验研究了吸附气对产气特征的影响。结果表明：视吸附量先随压力增大而增大,到达峰值之后视吸附量随压力的增大而减小;在低压条件下,采用Langmuir外推计算的吸附气量与高压实验计算的吸附气量相差不大;而在高压条件下,采用低压Langmuir理论推算总含气量高估9.2%;低于临界解吸压力时,吸附气解吸附使得单位压差产气量增加;高于临界解吸压力时,吸附气对单位压差产气量几乎没有影响;开发初期,低于临界解吸压力范围较小,吸附气对产气量贡献较小,尽可能动用游离气是高效开发的关键。 相似文献