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通过对四川盆地重庆地区下志留统龙马溪组的钻井岩心和野外露头等进行分析,利用高压吸附仪分析了页岩中CH_4、CO_2气体的吸附性能,并采用N_2吸附法、CO_2吸附法、场发射扫描电子显微镜(FE—SEM)和X-射线衍射(XRD)等技术,从孔隙结构、有机碳含量、矿物成分、温度和单位压力变化等方面探讨页岩吸附能力的影响关系。研究表明,龙马溪组页岩CH_4、CO_2吸附曲线具有Ⅰ型等温线特征,用Langmuir模型回归等温线能较好地拟合实验数据;页岩的总孔体积、比表面积与饱和吸附量体现良好的线性相关关系,且正相关;页岩有机质和矿物成分通过控制着微米—纳米级孔隙的相对丰度影响着气体的吸附和储存,微孔、中孔孔体积及孔隙度均随总有机碳含量(TOC)值增加而增大;TOC值越大,页岩的饱和吸附量就越大,二者具有良好的正相关性;吸附气量与黏土矿物含量呈正线性相关,与脆性矿物含量呈现相反的变化规律。温度升高会加快气体解吸速度,降低吸附量;此外,页岩对CO_2吸附能力高于CH_4。
By analyzing the drilling core and outcrop of the Lower Silurian Longmaxi Formation in the Chongqing area of Sichuan Basin, the adsorption properties of CH 4 and CO 2 in shale were analyzed by high pressure adsorption apparatus. The adsorption characteristics of CH 4 and CO 2 in the shale were analyzed by N 2 adsorption, CO 2 adsorption, Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used to investigate the influence of shale adsorption capacity on pore structure, organic carbon content, mineral composition, temperature and unit pressure. The results show that the CH 4 and CO 2 adsorption curves of Longmaxi shale have the characteristics of type Ⅰ isotherm. The Langmuir model isotherm can well fit the experimental data. The total pore volume, specific surface area and saturated adsorption capacity of shale show good The correlations between the organic matter and mineral components in shale affect the gas adsorption and storage by controlling the relative abundance of micropores and nanoscale pores. The micropores, mesopore volume and porosity are positively correlated with the total organic carbon The content of TOC increases with the increase of TOC value. The larger the TOC value is, the larger the saturated adsorption amount of shale is, and the two have a good positive correlation. The content of adsorbed gas is positively correlated with the content of clay minerals and opposite to that of brittle minerals The law of change. The temperature increase will accelerate the gas desorption rate, reduce the amount of adsorption; In addition, shale adsorption capacity of CO_2 higher than CH_4.