Genetic mechanism and petroleum geological significance of calcite veins in organic-rich shales of lacustrine basin:A case study of Cretaceous Qingshankou Formation in Songliao Basin,China  

作　　者：HE Wenyuan SUN Ningliang ZHANG Jinyou ZHONG Jianhua GAO Jianbo SHENG Pengpeng 

机构地区：[1]China National Oil and Gas Exploration and Development Corporation,Beijing 100034,China [2]National Key Laboratory for Multi-resource Collaborated Green Development of Continental Shale Oil,Daqing 163712,China [3]Ocean Engineering Research Institute,Northeastern University,Qinhuangdao 066004,China [4]School of Resources and Materials,Northeastern University at Qinhuangdao,Qinhuangdao 066004,China [5]National Engineering Research Center of Offshore Oil and Gas Exploration,Beijing 100028,China [6]Exploration and Development Research Institute of CNPC Daqing Oilfield Company Limited,Daqing 163712,China [7]School of Geosciences,China University of Petroleum(Eastern China),Qingdao 266580,China

出　　处：《Petroleum Exploration and Development》2024年第5期1083-1096,共14页石油勘探与开发（英文版）

基　　金：Supported by the Natural Science Foundation of Hebei(D2024501002);Fundamental Research Funds for the Central Universities(N2423020);Major Science and Technology Projects of CNPC(2021ZZ10)。

摘　　要：Based on the observation and analysis of cores and thin sections,and combined with cathodoluminescence,laser Raman,fluid inclusions,and in-situ LA-ICP-MS U-Pb dating,the genetic mechanism and petroleum geological significance of calcite veins in shales of the Cretaceous Qingshankou Formation in the Songliao Basin were investigated.Macroscopically,the calcite veins are bedding parallel,and show lenticular,S-shaped,cone-in-cone and pinnate structures.Microscopically,they can be divided into syntaxial blocky or columnar calcite veins and antitaxial fibrous calcite veins.The aqueous fluid inclusions in blocky calcite veins have a homogenization temperature of 132.5–145.1℃,the in-situ U-Pb dating age of blocky calcite veins is(69.9±5.2)Ma,suggesting that the middle maturity period of source rocks and the conventional oil formation period in the Qingshankou Formation are the sedimentary period of Mingshui Formation in Late Cretaceous.The aqueous fluid inclusions in fibrous calcite veins with the homogenization temperature of 141.2–157.4℃,yields the U-Pb age of(44.7±6.9)Ma,indicating that the middle-high maturity period of source rocks and the Gulong shale oil formation period in the Qingshankou Formation are the sedimentary period of Paleocene Yi'an Formaiton.The syntaxial blocky or columnar calcite veins were formed sensitively to the diagenetic evolution and hydrocarbon generation,mainly in three stages(fracture opening,vein-forming fluid filling,and vein growth).Tectonic extrusion activities and fluid overpressure are induction factors for the formation of fractures,and vein-forming fluid flows mainly as diffusion in a short distance.These veins generally follow a competitive growth mode.The antitaxial fibrous calcite veins were formed under the driving of the force of crystallization in a non-competitive growth environment.It is considered that the calcite veins in organic-rich shale of the Qingshankou Formation in the study area has important implications for local tectonic activities,fluid overpressure,

关 键 词：Songliao Basin calcite vein in-situ LA-ICP-MS U-Pb dating horizontal extrusion force of crystallization OVERPRESSURE shale oil CRETACEOUS Qingshankou Formation 

分 类 号：TE14[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]