东营凹陷沙河街组沙三、沙四段泥页岩微观孔隙特征分析

Analysis of microscopic pore characteristics of shale in Shahejie Formation of Dongying depression

泥页岩储集空间存在着丰富的纳米级和微米级孔隙,这些微观孔隙的存在对研究页岩油气的储集、运移具有重要意义。基于井下岩心样品及钻井资料,通过岩石热解、X射线衍射、氩离子抛光-扫描电镜以及JmicroVision软件,对东营凹陷沙三下亚段和沙四上亚段所挑选的7块泥页岩微观孔隙结构特征进行分析,并将不同矿物组合对孔隙发育的影响进行探讨。研究结果表明,研究区沙三下亚段和沙四上亚段烃源岩总有机碳含量为好-最好烃源岩程度,干酪根表现为Ⅰ型和Ⅱ1型;发育多种成因类型微观孔隙,主要以有机质孔、粒间孔、粒内孔、微裂缝以及古生物化石孔为主,且粒间孔和粒内孔是总面孔率的最大贡献者;脆性矿物含量和碳酸盐岩矿物含量分别与孔隙发育程度呈负相关和正相关关系。

The reservoir space of shale has a wealth of nano-pores and micron-pores.The existence of these micro pores is of great significance for studying the storage and migration of shale oil and gas.Based on underground core samples and drilling data,the microscopic pore structure characteristics of 7 selected shale blocks in the lower and upper Sha-3 and Sha-4 sub sections of Dongying depression were analyzed through rock-eval,XRD,argon ion polishing-scanning electron microscopy and JmicroVision software.The influence of different mineral combinations on pore development was discussed.The research results indicate that the total organic carbon content of the source rocks in the lower and upper Sha-3 and Sha-4 sub sections of the study area is good-the best degree of source rock,and the kerogen exhibits typeⅠandⅡ1.Multiple types of micro pores are developed,mainly composed of organic matter pores,intergranular pores,intragranular pores,microcracks,and paleontological fossil pores,with intergranular pores and intragranular pores being the largest contributors to the total porosity.The content of brittle minerals and carbonate minerals are negatively and positively correlated with the degree of pore development,respectively.