江西省富有机质页岩孔裂隙结构特征及其对页岩气富集的影响

发布时间：2018-08-14 20:17

【摘要】：以江西省泥页岩储层为研究对象,通过野外地质观测、老井复查、样品采集,采用扫描电子显微镜、高压压汞实验、低温液氮吸附脱附实验、核磁共振、阴极发光、甲烷等温吸附实验等测试方法,系统研究了江西省泥页岩储层孔裂隙发育类型、孔隙结构、孔隙度等相关孔裂隙发育特征,探讨了泥页岩储层孔裂隙发育的影响因素,分析了孔裂隙结构对页岩气富集的影响。研究工作取得如下主要认识:1)江西省泥页岩储层存在有机质孔、矿物质孔两大类孔隙。有机质孔包括原生有机质孔、有机质生烃孔。矿物质孔以黏土矿物间孔为主,主要有粒间孔、粒内孔、晶间孔、溶蚀孔等类型。宏观裂隙以大型剪裂缝为主,包括“X”型共轭剪裂缝等。微裂缝发育类型主要为粒内裂缝、粒缘裂缝、综合型微裂缝,包括有机质生烃缝、收缩缝等多种类型。储集空间包括嵌套型、串珠状孔隙、簇状孔隙、集群孔隙等组合类型。2)储层中的孔隙是从纳米级至厘米级连续完整孔隙系统,且介孔(2-50nm)比例较高。纳米孔隙多为瓶状、狭缝状及无规则开放孔。介孔提供了主要的孔隙体积,介孔及微孔提供了95%以上的比表面积。江西省泥页岩储层均属于特低孔-超低孔、超低渗-非渗储层。储层样品均表现为超低含水饱和度、低可动水饱和度、高束缚水饱和度、中等含气饱和度。超低含水饱和度现象可有效增加页岩气渗流能力但对页岩气开发造成一定风险。孔隙发育是由外因(构造作用、岩浆活动、成岩作用)和内因(矿物组成、生气压裂作用)两大因素控制。3)泥页岩储层现场解析气量偏低,但等温吸附最大理论吸附量达到了北美商业开发的页岩气含气量的要求。其中,赣西北地区王音铺组吸附能力最优。有机质孔的含量与储层吸附能力具有正相关关系。泥页岩储层甲烷最大吸附量与比表面积、孔体积具有正相关趋势。介孔表面积、大孔表面积、大孔体积与甲烷最大吸附量的相关性较强,微孔表面积、孔体积并未表现出很强的相关性。主要的原因在于甲烷分子在微孔及介孔表面吸附方式不同:微孔中范德华力重叠,甲烷分子排列无规则;介孔中甲烷分子发生单分子层吸附,能以单层“均匀规则”的吸附于孔隙壁表面。孔隙度与吸附含气量的线性关系不明显,但孔隙度对页岩气赋存相态有显著影响。泥页岩储层中的输导体系主要有裂隙型、孔隙-裂隙型、孔隙带型。
[Abstract]:Taking the shale reservoir of Jiangxi Province as the research object, through field geological observation, old well review, sample collection, scanning electron microscope, high pressure mercury injection experiment, low temperature liquid nitrogen adsorption and desorption experiment, nuclear magnetic resonance, cathodoluminescence, By means of methane isothermal adsorption test and other testing methods, the characteristics of pore and fissure development of shale reservoir in Jiangxi Province, such as pore fracture type, pore structure, porosity and so on, are systematically studied, and the influencing factors of pore fracture development in shale reservoir are discussed. The effect of pore structure on shale gas enrichment is analyzed. The main results are as follows: (1) there are two kinds of pores in shale reservoirs in Jiangxi Province: organic pore and mineral pore. Organic pore includes primary organic pore and organic hydrocarbon generation pore. Mineral pores mainly consist of intergranular pores, dissolution pores and so on. Macro fractures are mainly large shear cracks, including X-type conjugate shear cracks. The main types of microfractures are intragranular cracks, grain edge fractures, comprehensive microfractures, including organic hydrocarbon generation fractures, shrinkage fractures and other types. The reservoir space is composed of nested, beaded, cluster and cluster pores. 2) the pores in reservoirs are continuous and complete from nanometer to centimeter, and the ratio of mesoporous (2-50nm) is relatively high. Nano-pores are mostly bottle-shaped, slit-shaped and irregular open pores. Mesoporous provides the main pore volume, mesoporous and micropores provide more than 95% of the specific surface area. The shale reservoirs in Jiangxi Province belong to very low porosity-ultra low porosity and ultralow permeability non-permeable reservoirs. The reservoir samples are characterized by ultra-low water saturation, low movable water saturation, high irreducible water saturation and medium gas saturation. The phenomenon of ultra-low water saturation can effectively increase the percolation capacity of shale gas but cause certain risks to the development of shale gas. Pore development is controlled by external factors (tectonism, magmatic activity, diagenesis) and internal factors (mineral composition, gas fracturing). However, the maximum theoretical adsorption capacity of isothermal adsorption reached the requirement of shale gas content developed commercially in North America. Among them, the adsorption capacity of Wangyinpu formation in northwest Jiangxi is the best. There is a positive correlation between the content of organic matter pore and the adsorption ability of reservoir. The maximum adsorption capacity of methane and specific surface area and pore volume of shale reservoir have a positive correlation trend. The correlation between mesoporous surface area, macropore volume and the maximum adsorption capacity of methane is strong, but the micropore surface area and pore volume do not show strong correlation. The main reason is that methane molecules are adsorbed in different ways on the microporous and mesoporous surfaces: the Van der Waals force overlaps in the micropores, the methane molecules are arranged irregularly, and the methane molecules in the mesoporous molecules are adsorbed by monolayers. It can be adsorbed on the surface of pore wall by single layer "uniform rule". The linear relationship between porosity and adsorbed gas content is not obvious, but porosity has a significant effect on the phase state of shale gas. The transport system in shale reservoir mainly includes fracture type, pore-fissure type and pore zone type.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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