渤海湾盆地东营凹陷古近系沙河街组页岩储层润湿性及其主控因素  

Wettability and its major determinants of shale reservoirs in the Shahejie Formation,Dongying Sag,Bohai Bay Basin

作　　者：李倩文 LI Qianwen(State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 102206,China;Key Laboratory of Shale Oil/Gas Exploration and Production Technology,SINOPEC,Beijing 102206,China;Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100026,China)

机构地区：[1]页岩油气富集机理与高效开发全国重点实验室,北京102206 [2]中国石化页岩油气勘探开发重点实验室,北京102206 [3]中国石化石油勘探开发研究院,北京102206

出　　处：《石油与天然气地质》2024年第4期1142-1154,共13页Oil & Gas Geology

基　　金：中国石油化工股份有限公司科技部项目(KLP23012)。

摘　　要：润湿性影响储层页岩油的赋存状态和渗流规律,是评价页岩储层的重要内容。对渤海湾盆地济阳坳陷东营凹陷古近系沙河街组页岩开展接触角测定和自发渗吸实验,定量表征储层的润湿性特征,分析研究润湿性的主控因素,从而对储层进行优选评价。研究结果表明:沙河街组页岩储层孔隙连通性中等,具有斑状润湿特征,总体为水湿-弱水湿。储层润湿性受有机质特征、矿物组成、孔隙孔径大小和页岩油组分控制。有机质和矿物组成对润湿性的影响由固体颗粒本身的界面张力决定。有机质丰度越高,矿物组成中钙质含量越高,储层的水湿性越差,油湿性越好。含油性和页岩油组分改变了液体的表面张力,从而影响储层润湿性。储层含油性越好,原油中极性组分越多,油湿性越好。孔隙结构通过毛细管力作用影响固、液表面的界面张力,进而影响润湿性。储层孔隙孔径越大,水湿性越差,油湿性越好。从润湿性特征评价,纹层状富有机质富钙质页岩的亲油性最好,且在弱水湿条件下页岩油较易富集成藏,相对容易开采,是页岩油勘探开发的有利选择。Wettability,a factor influencing the occurrence and seepage patterns of shale oil in reservoirs,is an important indicator of shale reservoir evaluation.Using contact angle measurements and spontaneous imbibition experiments,we quantitatively characterize the wettability of shale reservoirs in the Shahejie Formation,Dongying Sag,Bohai Bay Basin,while delving into the primary determinants of wettability,and selecting the optimal reservoirs for assessment.The findings suggest that the shale reservoirs in the Shahejie Formation exhibit moderate pore connectivity and fractional wettability,generally proving to be water-wet to weakly water-wet.The reservoir wettability is jointly determined by organic matter characteristics,mineral components,pore size,and shale oil composition.The impacts of organic matter and mineral composition on reservoir wettability depend on the interfacial tension of solid particles.Specifically,a higher abundance of organic matter and a higher calcium content in minerals are associated with reduced water wettability and stronger oil wettability of the reservoirs.The oil-bearing capacity and shale oil components alter the surface tension of liquids,further influencing the reservoir wettability.A higher oil-bearing capacity of reservoirs and the presence of more polar components in crude oil suggest stronger oil wettability.Pore structure influences the solidliquid interfacial tension through capillary pressure,further affecting the reservoir wettability.A larger pore size corresponds to weaker water wettability and stronger oil wettability of the reservoirs.The wettability assessment results demonstrate that lamellar organic-rich calcareous shales exhibit the strongest lipophilicity.Shale oil tends to be enriched and accumulate in these shales under weakly water-wet conditions,creating conducive conditions for shale oil production.Therefore,these shales serve as favorable targets for shale oil exploration and production.

关 键 词：接触角 自发渗吸 储层润湿性 页岩 沙河街组 东营凹陷 渤海湾盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]