成岩流体演化对致密砂岩气藏储层质量的控制作用研究

The abundant unconventional natural gas resources, if exploited reasonably and efficiently, will provide stable energy supply for the sustainable development of Chinese economy. Palaeozoic tight sandstone gas reservoir of the Daniudi gas field in northern Erdos Basin is the main research object. Using many experimental technology, such as thin section observation, scanning electron microscope, X-ray diffraction analysis, cathodoluminescence and so on, diagenetic events and diagenetic series were studied firstly. Through the study of the diagenetic mineral types and their spatial distribution characteristics, diagenesis types, diagenesis characteristics, diagenetic events and diagenetic evolution process were analysed in details. Secondly, By means of the fluid inclusions analytical technology and laser raman spectroscopy experiment, some parameters of the secondary inclusions in reservoir, such as temperature, pressure, fluid phase composition, salinity and pH value were measured, fluid type, fluid composition and fluid properties were analysed combined with diagenetic products, diagenetic fluid evolution characteristics were summarized and the diagenetic environment was restored. Finally, based on all of the research results, the controlling effects of diagenetic fluid evolution on tight sandstone gas reservoir quality were summarizesd. By studying the fluid properties and physical and chemical environment in the period of the diagenetic authigenic mineral formed in different diagenetic stages, the loss rate and contribution rate of diagenesis on reservoir porosity in different diagenetic stages were analysed and the evolution law of pore space was revealed. The research results will indicate the direction for the secondary pores belt exploration and high quality reservoirs prediction.

我国非常规天然气资源丰富，合理有效地开发可为中国经济的可持续发展提供能源保障。以鄂尔多斯盆地北部大牛地气田古生界致密砂岩气藏为主要解剖区，利用薄片观察、扫描电镜、X-衍射分析、阴极发光等实验技术手段，首先开展储层成岩事件及成岩系列研究，通过研究储层造岩矿物、成岩矿物类型及其空间分布特点，确定储层成岩作用类型及特征，明确储层成岩事件及成岩演化历程。其次，利用流体包裹体研究技术、激光拉曼光谱实验等手段，测定储层中次生包裹体温压、流体相成分、盐度、pH值等参数，结合成岩产物判断流体类型、组分及性质，总结成岩流体演化特征，恢复成岩环境。综合上述研究成果，分析成岩流体演化对储层质量的控制作用，通过研究各成岩阶段自生矿物形成时流体的性质及其物理化学环境，分析不同成岩阶段下成岩作用对储层孔隙的损失率和贡献率，明确孔隙空间演化规律，为寻找次生孔隙发育带及预测优质储层指明方向。

我国非常规天然气资源丰富，合理有效地开发可为中国经济的可持续发展提供能源保障。以鄂尔多斯盆地北部大牛地气田上古生界致密砂岩气藏为主要解剖区，利用薄片观察、扫描电镜、X-衍射分析、阴极发光等实验技术手段，开展储层成岩事件及成岩系列研究，通过研究储层造岩矿物、成岩矿物类型及其空间分布特点，确定储层成岩作用类型及特征，明确储层成岩事件及成岩演化历程。研究表明研究区太原组以纯石英砂岩为主，山西组和下石盒子组均以岩屑砂岩和岩屑石英砂岩为主，粒间溶孔及溶蚀扩大孔、粒内溶孔是砂岩的主要孔隙类型。成岩作用主要包括机械压实、多期次的硅质胶结和钙质胶结，溶解作用包括酸性溶解和碱性溶解两种。在此基础上，利用流体包裹体研究技术、激光拉曼光谱实验等手段，测定储层中次生包裹体温压、流体相成分、盐度、pH值等参数，结合成岩产物判断流体类型、组分及性质，总结成岩流体演化特征，恢复成岩环境。将成岩演化过程按时间次序依次划分为：Ⅰ-快速压实、Ⅱ-酸碱交替、Ⅲ-致密化和Ⅳ-致密后四个阶段，深入研究了每个阶段的成岩特征及与天然气充注的关系。综合上述研究成果，分析成岩流体演化对储层质量的控制作用，通过研究各成岩阶段自生矿物形成时流体的性质及其物理化学环境，分析不同成岩阶段下成岩作用对储层孔隙的损失率和贡献率，重点分析了储层杂基含量、压实作用、胶结作用对储层质量的影响。研究成果为研究区致密砂岩气藏的勘探开发提供了依据，具有一定的理论和实际应用价值。