渤海湾盆地济阳坳陷高产页岩油井BYP5页岩地质特征

Geology of shales in prolific shale-oil well BYP5 in the Jiyang Depression， Bohai Bay Basin

刘惠民 李政 包友书 张守春 王伟庆 吴连波 王勇 朱日房 方正伟 张顺 刘鹏 王敏

Huimin LIU Zheng LI Youshu BAO Shouchun ZHANG Weiqing WANG Lianbo WU Yong WANG Rifang ZHU Zhengwei FANG Shun ZHANG Peng LIU Min WANG

济阳坳陷高产页岩油井BYP5古近系沙河街组三段下亚段（沙三下亚段）页岩为高成熟、富碳酸盐页岩典型代表，研究其地质特征对相似页岩勘探具有借鉴意义。从矿物组成、薄层结构、生烃条件、烃类流体性质、储集空间特征等方面剖析了该页岩基本特点。基于地化参数异常分析了页岩油微运移调整、富集机制，确定了页岩油可动的油饱和度指数（）、总有机碳含量（）及孔隙度下限。研究了有利于页岩油高产的地质条件。研究表明：BYP5井沙三下亚段页岩以碳酸盐质页岩为主，具有明显的薄层结构特征，薄层类型主要包括泥质薄层和泥晶方解石薄层。为0.58 %～7.98 %，平均4.52 %，以Ⅰ型有机质为主，处于生轻质油-凝析气阶段。孔隙度为2.2 %～6.9 %，平均3.22 %，储集空间包括基质孔、层间缝以及穿层缝，其中基质孔是主要储集空间类型。可动页岩油的下限值低于50 mg/g，下限值为1 %，孔隙度下限为2.2 %。利于高产的地质条件是：①较高的有机质丰度和生烃潜力，为石油富集及流动奠定坚实物质基础；②油气具有较好的流动性，可大大降低有效储集物性下限；③异常高压为石油产出提供了充足的天然能量；④页岩的纹层状/层状结构特征决定了其具有较高的生-储-渗效率；⑤层间缝和穿层缝等多种裂缝发育，可有效沟通裂缝两侧的基质孔隙，有利于基质孔中石油产出。

Shales in the lower sub-member of the 3 member of the Paleogene Shahejie Formation （E section） in prolific shale-oil well BYP5 in the Jiyang Depression are of typical carbonate-rich type with high maturity. Research on their geological characteristics is of analogy and reference significance for the exploration of similar shales. We delve into the basic characteristics of these shales in terms of mineral composition， thin layer structure， hydrocarbon-generating condition， hydrocarbon fluid property， and reservoir space type. Based on the anomalies of geochemical parameters， we discuss the micro-migration adjustment and accumulation mechanism of shale oil， determine the lower limit of the oil saturation index （）， total organic carbon （） content， and porosity for shale oil mobility. Therefore， the geological conditions favorable for high shale oil production are concluded. As revealed by this study， shales in the E section in well BYP5 is predominantly of carbonate-rich type， characterized by thin layer structure dominated by argillaceous and micritic calcite thin layers. With content ranging from 0.58 % to 7.98 % （average： 4.52 %） and Type Ⅰ organic matter predominating， the shales in the study area are at the stage of light oil and condensate gas generation. With porosity between 2.2 % and 6.9 % （average： 3.22 %）， the dominant storage spaces are matrix pores， followed by inter-layer and cross-cutting fractures. The lower limit of the shales’ OSI for oil prodution is less than 50 mg/g， while that of their content and porosity for oil prodution is 1 % and 2.2 %， respectively. The geological conditions favorable for high shale oil production are as follows： （1） High organic matter abundance and high hydrocarbon-generating potential as a result serve to lay a solid material foundation for oil enrichment and flow； （2） High hydrocarbon mobility significantly reduces the lower limit of effective reservoir properties for hydrocarbon storage； （3） Abnormally high pressures provide sufficient natural energy for oil production； （4） The lamellar/layered structures of shales determine the high efficiency of hydrocarbon generation， storage， and permeability of the reservoir； （5） Multiple types of fractures like inter-layer and cross-cutting fractures can effectively connect matrix pores on both sides of the fractures， facilitating the oil recovery from the matrix pores.

10.11743/ogg20230606