渤海湾盆地济阳坳陷古近系陆相富有机质页岩裂缝研究

The development degree of fractures in organic-rich shale has a direct influence on the efficiency of shale oil and gas development. The project aims at a hot researched question-the study of fractures in continental shale reservoir. It takes the lacustrine Shahejie formation Sha3 section organic-rich shale as an example, which bases on the materials including drilling information of Sha3 section shale, cores from 40 oil or gas bearing wells, logging (FMI included) material, oil production and formation pressure. Beside, in order to make a comprehensive distinction of fracture developed layers in different levels and give a systematic study for the characteristics of micro-fractures and nanometer ultra-micro fractures in shale reservoir, the project uses advanced experimental methods and instruments, such as thin section, argon ion polishing, field emission scanning electron microscopy,transmission electron microscope, nano-CT and magnetic resonance imaging. By using the methods of X-ray diffraction, organic geochemistry, high temperature and pressure triaxial rock mechanics experiment and AE tectonic stress test, the data can be obtained including the mineral components、organic contents、parameters on rock mechanics properties、paleo-tectonic stress、abnormal formation pressure、shear stress、tensile stress and fractures cracking rate. The project also make a quantitative evaluation on the controlling factors of fractures development in Sha3 shale, and establish a mathematical model to show the quantitative relationship between fracture development degree and its main controlling factors, which may play important role in the establishment of the theory and the development of continental shale oil and gas in the depression of eastern China.

富有机质页岩裂缝发育程度直接影响着油气藏的开采效益，项目针对当前陆相泥页岩储层裂缝研究的热点问题，以我国东部济阳坳陷沙河街组三段湖相富有机质泥页岩为例，依据钻揭沙三段泥页岩，并见油气显示40口钻井的岩心、测井（含FMI）、气测、地震、地层压力等资料，采用岩石光薄片、氩离子抛光、场发射扫描电镜、透射电镜、纳米-CT和核磁共振等技术，综合识别页岩不同级别裂缝层段，系统研究页岩储层微裂缝和纳米级超微缝特征；利用X-衍射、有机地球化学、高温高压三轴岩石力学、声发射地应力测试等先进实验方法和构造应力场数值模拟技术，获取裂缝层段的矿物组成、有机碳含量、岩石力学参数、古构造应力、异常地层压力、剪应力、张应力和裂缝综合破裂率等数据，定量分析沙三段泥页岩裂缝发育主控因素，建立裂缝发育程度与主控因素之间定量关系数学模型。项目成果将对于我国东部断陷湖盆陆相页岩油气地质理论建立和勘探开发均具有重要意义。

渤海湾盆地济阳坳陷古近系沙河街组三段富有机质页岩层系是页岩油勘探开发的对象，页岩裂缝发育程度直接影响着页岩油藏的品质和开采效益。该项目充分利用了研究区内地质、钻井、测井（含特殊测井）、岩心样品等资料，采用岩石薄片、氩离子抛光、场发射扫描电镜、高温高压三轴岩石力学实验、声发射地应力测试、测井裂缝评价、构造应力场数值模拟等先进技术方法，系统深入开展了陆相富有机质泥页岩裂缝发育层段综合识别与特征参数表征研究、裂缝发育层段主控因素定量研究、裂缝发育程度与主控因素之间定量关系数学模型研究、裂缝发育对页岩含油性影响研究。. 明确了济阳坳陷古近系沙三下亚段湖相富有机质页岩的矿物学和地球化学特征，确定了沙三下亚段页岩层中有机质富集主要贡献来自于表层水较高的原始生产力，水体分层条件对有机质富集起到了一定保护作用,这对识别济阳坳陷古近系沙三下亚段陆相富有机质页岩发育层段具有重要应用价值。 建立的渤海湾盆地济阳坳陷古近系陆相富有机质页岩岩相测井识别方法与特征，明确指出沙三下亚段中下部的层状灰质页岩和纹层状粘结岩岩相段为该地区更为有利的页岩油勘探和开发目的层段。此结果对研究区古近系页岩油的勘探目的层的优选提供了重要的基础理论依据。形成的一整套页岩储层地球物理测井评价技术方法，特别是对页岩气储层裂缝发育有利区（甜点）预测，为页岩气勘探开发水平井井位部署提供更可靠的依据。 提出的页岩微观孔隙-裂缝成因类型划分的方法，对确定富有机质页岩储集空间类型及形成机制具有重要使用价值。明确了页岩储层裂缝识别方法与表征、页岩储层体积压裂缝网形成的主控因素及评价方法。探讨了地应力、天然裂缝对水力压裂缝的影响，此结果对页岩气储层改造与水平井轨迹优选具有重要指导作用。提出了页岩储层二维和三维构造应力场模拟与裂缝分布预测方法，对于页岩气勘探开发早期缺少三维地震资料的地区含气页岩储层裂缝的分布预测具有普遍适用价值。