白云岩对陆相湖盆泥页岩层系储层物性和脆性的影响定量研究

A considerable part of the oil and gas resources contained in continental lacustrine shale formation is related to lacustrine carbonate rocks in China, and many of the shale formation of the oil and gas reservoir develop numerous dolomites, even with the dolomite as the main reservoir. Thus, the origin and content of dolomite has an important effect to the reservoir properties and brittleness heterogeneity of lacustrine shale formation. We should consult the previous research methods and results of genetic mechanisms of target reservoir dolomite and comprehensively analyze the data of the core observation, thin section identification, geochemical analysis, X-ray diffraction analysis, scanning electron microscope, electron microprobe and cathodoluminescence. According to the different genetic mechanisms of the dolomite, the shale reservoir samples will be classified by designing reasonable target shale reservoirs samples sampling scheme. The quantitative relationship, between dolomite content of different genetic mechanisms and the reservoir properties of lacustrine shale formation, can be established through overburden pressure porosity, permeability measurements and geochemical analysis. Meanwhile, the quantitative relationship among the dolomite content of different genetic mechanisms, organic matter abundance and maturity and shale reservoir properties will be discussed. The contribution of the dolomite content to the elastic parameters of rock will be determined based on the X-ray diffraction analysis and triaxial compression test. Consequently the quantitative relationship between dolomite content and shale reservoir brittleness can be established.

我国陆相湖盆泥页岩层系油气资源相当大一部分与湖相碳酸盐岩相关，且许多泥页岩层系油气发育区储层中含有大量的白云（质）岩，甚至以白云（质）岩类为主要储层，白云岩的成因及含量对于陆相湖盆泥页岩层系储层物性和脆性具有重要的影响。通过设计合理的靶区泥页岩储层样品采样方案，参考前人对靶区白云岩成因机制的研究方法和成果，综合岩心观察、薄片鉴定、地球化学分析、X衍射全岩分析、扫描电镜、电子探针、阴极发光等分析数据，对泥页岩储层样品按照白云岩成因机制进行分类。通过统一的覆压孔渗测试和地球化学分析，拟合建立不同成因机制的白云石含量与陆相湖盆泥页岩储层物性的定量关系，探讨不同成因机制的白云石含量、有机质丰度和成熟度与泥页岩储层物性之间的定量关系。基于X衍射全岩分析与三轴应力压缩实验，确定白云石含量对岩石弹性参数的贡献程度，建立白云石含量与泥页岩储层脆性的定量关系。

我国陆相湖盆泥页岩层系油气资源相当大一部分与湖相碳酸盐岩相关，且许多泥页岩层系油气发育区储层中含有大量的白云（质）岩，甚至以白云（质）岩类为主要储层，白云石含量对陆相湖盆泥页岩层系储层物性与脆性具有重要影响。. 本课题在前人对靶区白云岩成因机制的研究方法和成果基础上，综合岩心观察、薄片鉴定、地球化学分析、扫描电镜等分析数据，对靶区泥页岩储层样品按照白云岩成因机制进行分类；通过统一的覆压孔渗测试和地球化学分析，拟合建立不同成因机制的白云石含量与陆相湖盆泥页岩储层物性的定量关系。基于X衍射全岩分析与三轴应力压缩实验，确定白云石含量对岩石脆性指数的贡献程度，并建立白云石含量与泥页岩储层脆性的定量关系。.综上，本课题取得以下重要结果：（1）明确研究靶区白云石成因；（2）确定研究靶区湖相泥页岩储层矿物组成和分布特征，明确其与国内外主要泥页岩储层的差异性；（3）明确研究靶区湖相泥页岩受力变形及裂缝发育特征，并建立动静态杨氏模量转换关系；（4）建立湖相泥页岩白云石含量与储层孔隙度三段式的定量关系，并分析不同阶段的主要影响因素；（5）确定靶区湖相泥页岩储层中白云石对脆性的贡献程度，并建立白云石含量与脆性的三段式的变化关系，并明确不同阶段的主要影响因素。. 明确白云石的含量与湖相泥页岩储层物性和脆性的定量关系，对认识湖相泥页岩脆性破坏的机理及工程可压性评价有积极意义。从工程角度来讲，这对于完善泥页岩层系储层地质和工程“甜点”评价与预测方法体系、促进页岩层系油气资源勘探开发具有重要的实践价值，不仅有助于压裂参数及高品质页岩压裂段的优选，还能够促进水平井技术与水力压裂技术在页岩气开发中发挥最大的效果。