页岩油气甜点预测的储层地质力学基础理论研究

This project takes the Paleozoic marine shale gas in the southeastern Sichuan Basin and the Cenozoic continental shale oil in the Bohai Bay and Jianghan Basins for example. Based on data of outcrop, core, thin section, logging, sample test and production, and using the geological and geophysical methods, the fundamental theory of three core parameters of prediction of shale oil and gas sweet spot, i. e. brittleness, in-situ stress and natural fracture, will be studied. On the basis of comparison study of difference of shale oil and gas enrichment and shale macroscopic and microscopic characteristics, development mechanism and main control factors of shale oil and gas sweet spot will be firstly researched. Then, according to systemic test of rock physical parameters in different confining pressure and stress-strain conditions, and combining with data of acoustic loggings, the quantitative relationships between geophysical parameters and characteristic parameters of petrology and rock mechanics, configuration parameters of shale will be established. Based on formation condition and development rule of multi-scale fractures, the effectiveness of multi-scale fractures and their influences on enrichment and preservation of shale oil and gas will be clarified. Finally, the prediction methods of shale brittleness based on critical crack index, in-situ stress based on shale anisortropy and considered tectonic stress, and classified fractures impacted on enrichment and preservation of shale oil and gas will be formed. The research results not only can guide exploration and development of shale gas in the Sichan Basin and shale oil in the Bohai Bay and Jianghan Basins, but also can provide geological theory basis for prediction and scientific evaluation of shale oil and gas sweet spots.

本项目以四川盆地东南部页岩气为重点，结合渤海湾和江汉盆地页岩油为研究对象，利用地表露头、岩心、薄片、测井、测试和生产资料，应用地质和地球物理方法，拟对页岩油气甜点预测3个核心参数（脆性、地应力、天然裂缝）基础理论进行研究。在页岩油气富集差异性及页岩宏观与微观特征对比研究基础上，阐明页岩油气甜点发育机理和主控因素；通过页岩在不同围压和应力-应变条件下岩石物理参数系统测试，结合声波测井数据对比分析，建立页岩岩石学和岩石力学特征参数、结构参数与地球物理参数的定量关系；在页岩多尺度裂缝形成条件与发育规律研究基础上，明确不同尺度裂缝有效性及对页岩油气富集与保存影响；形成基于临界破裂指数的页岩脆性预测方法、考虑水平构造应力并适应页岩各向异性的地应力预测方法和影响页岩油气富集与保存的分类裂缝预测方法。研究成果不仅对四川盆地页岩气和渤海湾、江汉盆地页岩油勘探开发具有重要指导作用，还可为页岩油气甜点预测和科学评价提供地质理论基础。

页岩油气是我国非常规油气勘探开发的重点领域，资源量大，分布广，但勘探开发难度大。甜点区预测是页岩油气勘探开发的关键技术和公认技术难题，储层地质力学是预测页岩油气甜点的基础理论。针对页岩油气甜点预测的储层地质力学理论基础，项目以四川盆地南部海相页岩气和渤海湾盆地与江汉盆地陆相页岩油为例，开展了页岩油气储层甜点发育机理与主控因素、页岩油气储层脆性与地球物理参数定量模型、页岩油气储层地应力与地球物理参数定量关系、页岩油气储层多尺度裂缝主控因素与有效性评价等4个方面研究，取得了重要进展：（1）明确了海相页岩气与陆相页岩油储层的地质特征及其差异性，阐明了页岩油气储层甜点的发育机理和主控因素，为页岩油气储层甜点预测提供了基础。（2）通过大量的物理模拟实验，发现了页岩脆性的各向异性特征及其主控因素，建立了页岩脆性与地球物理参数的定量关系和脆性各向异性岩石物理模型，在此基础上提出了基于页岩岩石物理模型的脆性预测方法。（3）阐明了页岩储层地应力分布特征、变化规律及其主控因素，建立了页岩地应力与地球物理参数的定量关系和各向异性页岩地应力定量计算模型，在此基础上形成了页岩地应力定量评价方法和地质约束的页岩地应力地震预测方法。（4）阐明了页岩储层天然裂缝的成因类型、形成机理及主控因素，明确了不同类型天然裂缝对页岩气富集与保存的影响，形成了断层相关裂缝发育带的精细刻画方法、地质与地球物理相结合的水平页理缝评价方法和预测方法以及基于构造变形强度的页岩气分区定量评价方法。研究成果在四川盆地涪陵地区海相页岩气、渤海湾盆地沾化凹陷陆相页岩油、江汉盆地潜江凹陷陆相页岩油和鄂尔多斯盆地陆相页岩油勘探开发中应用，取得了良好应用效果和显著经济与社会效益，为我国页岩油气甜点预测及勘探开发提供了地质理论基础和核心技术支持。