渤海湾盆地沾化凹陷沙河街组页岩油微观储集性

摘要

探讨渤海湾盆地沾化凹陷页岩油储层不同岩石矿物的孔隙发育特征,为页岩油勘探开发提供基础资料.取自沾化凹陷罗69井古近系沙河街组页岩油层段21块自然断面和氩离子抛光岩心样品,利用场发射扫描电镜图像定量研究页岩油储层不同岩石矿物的孔隙发育类型、孔径分布及其面孔率贡献.结果表明沙河街组页岩油主要孔隙类型有泥岩中的泥质碎片间微孔和泥晶灰岩中的方解石溶蚀孔,其中的微米级孔隙提供了页岩油的主要储集空间.纳米级孔径为主的方解石晶间孔、晶内孔和黄铁矿晶间孔数量多,但孔隙面孔率很低.沾化凹陷页岩油开发的主要对象为微米级泥质粒间孔和方解石溶蚀孔发育层段.%Pore development characteristics of different rocks and minerals in shale oil reservoir in Zhanhua Sag of Bohai Bay Basin are discussed and studied in order to provide basic data for exploration and development of shale oil.21 natural section and argon-ion polishing samples from Well Luo-69 for the Paleogene Shahejie Formation in Zhanhua Sag are selected,and the pore development types,pore size distributions and plane porosity contribution of different rocks and minerals of shale oil reservoir are quantitatively studied by field emission scanning electron microscope image analysis.It shows that the main pore types of shale oil in Shahejie Formation consist of argillaceous inter-particle pores in mudstone and calcite dissolved pores in micrite,and the micro-pores provide main reservoir space for shale oil.The amount of calcite inter-crystal pores,intra-crystal pores and pyrite inter-crystal pores are mainly in nanometer scale with very low pore plane porosity.It reveals that the main target of shale oil development in Zhanhua Sag is the developed intervals of micro-scale argillaceous inter-particle pores and calcite dissolved pores.