泥页岩储层微观孔隙结构模型及吸附能力研究

发布时间：2018-10-04 23:16

【摘要】：随着技术手段的提升,非常规油气开发取得长足进步,页岩气作为非常规气藏的重要组成部分,获得广泛关注。本文通过对页岩气藏孔隙结构与吸附能力的理论和实验研究,对其储层微观孔隙结构和气体储集方式有了深入的认识。本文以四川盆地龙马溪组页岩为研究对象,结合国内外研究现状开展研究,主要包括X射线衍射、X射线荧光、扫描电镜、核磁共振、低压氮气吸附、高压甲烷吸附等实验。通过研究分析得到龙马溪组页岩岩性、地化特征、孔隙结构和吸附能力等相关特性参数。综合各种实验方法,总结出了一套适合泥页岩室内岩心实验的方法流程。通过扫描电镜观察,本文对龙马溪组页岩孔隙和裂缝进行分类,按照成因来源将基质孔隙分为无机孔隙和有机质孔隙。无机孔隙主要包括粒状颗粒粒间孔、黏土粒间孔、晶间孔、边缘孔为代表的粒间孔和粒内溶孔、生物孔组成的粒内孔。将裂缝分为构造张裂缝、构造剪裂缝、层间页理缝和成岩收缩缝。本文利用以分形理论为基础的孔隙结构模型,结合实验结果分析研究区内页岩孔隙的相关分形特征,得到了模型表征参数；通过建立多层分形吸附模型并结合对比Langmuir单层吸附模型、BET多层吸附模型和D-A模型,分析对比各个模型在页岩气藏拟合中的适用性。与此同时,在超临界压力的吸附实验中引入拟饱和蒸汽压概念,拓宽了BET模型和D-A模型的适用范围。通过拟合求得D-A模型特性曲线和BET模型净吸附热,拟合结果相关性系数达到0.99,对样品在未知温度的等温吸附情况进行预测,预测结果与实验情况吻合。页岩气的吸附量主要由页岩内部组成因素和外界环境因素决定。页岩的固有吸附能力受其孔隙结构和比表面积控制,而这两个参数又受页岩组成控制,这其中包括不同黏土矿物、石英和有机质的共同作用；此外温度、压力和含水率也会对页岩的吸附过程产生影响。
[Abstract]:With the improvement of technical means, unconventional oil and gas development has made considerable progress, shale gas as an important part of unconventional gas reservoirs, has received extensive attention. Based on the theoretical and experimental study on pore structure and adsorption capacity of shale gas reservoirs, this paper makes a deep understanding of the microscopic pore structure and gas reservoir mode of shale gas reservoirs. In this paper, the shale of Longmaxi formation in Sichuan Basin is taken as the research object, and the research is carried out at home and abroad, including X-ray diffraction X-ray fluorescence, scanning electron microscope, nuclear magnetic resonance, low pressure nitrogen adsorption, high pressure methane adsorption and so on. The shale lithology, geochemical characteristics, pore structure and adsorption capacity of Longmaxi formation were obtained. In this paper, a set of methods for core experiment in shale is summarized by synthesizing all kinds of experimental methods. The shale pores and fractures of Longmaxi formation were classified by SEM, and the matrix pores were divided into inorganic pores and organic pores according to the origin. Inorganic pores mainly include granular intergranular pores, clay intergranular pores, edge pores represented by intergranular pores and intragranular dissolved pores, and biopore composed of intragranular pores. The fractures are divided into structural tensional fractures, structural shear fractures, interlaminar lamellar fractures and diagenetic shrinkage joints. In this paper, the pore structure model based on fractal theory is used to analyze the fractal characteristics of shale pores in the study area, and the characterization parameters of the model are obtained. By establishing multilayer fractal adsorption model and comparing Langmuir monolayer adsorption model with Langmuir multilayer adsorption model and D-A model, the applicability of each model in shale gas reservoir fitting is analyzed. At the same time, the concept of quasi saturated vapor pressure is introduced into the adsorption experiment of supercritical pressure, which widens the application range of BET model and D-A model. By fitting the characteristic curve of D-A model and the net adsorption heat of BET model, the correlation coefficient of the fitting results is 0.99. The isothermal adsorption of the sample at unknown temperature is predicted, and the predicted results are in good agreement with the experimental results. The adsorption capacity of shale gas is mainly determined by the internal composition of shale and external environmental factors. The inherent adsorption capacity of shale is controlled by its pore structure and specific surface area, and these two parameters are controlled by shale composition, which includes the interaction of different clay minerals, quartz and organic matter, in addition to temperature, Pressure and moisture content also affect the adsorption process of shale.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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