上扬子地区五峰组—龙马溪组黑色页岩高频层序划分  

Division of high-frequency sequences in black shales of the Wufeng-Longmaxi formations,Upper Yangtze Region

作　　者：赵少泽 李勇[1] 程乐利 聂舟[4] 王同 吴朝容[6] 耿茂宇 ZHAO Shaoze;LI Yong;CHENG Leli;NIE Zhou;WANG Tong;WU Chaorong;GENG Maoyu(College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;Post-doctoral Research Station of Geology,Chengdu University of Technology,Chengdu 610059,China;Institute of Logging Technology and Engineering,Yangtze University,Jingzhou 434023,China;PetroChina Southwest Oil and Gasfield Company,Chengdu 610051,China;Sinopec Southwest Oil and Gas Company,Chengdu 610016,China;College of Geophysics,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]成都理工大学地质学博士后科研流动站,四川成都610059 [3]长江大学录井技术与工程研究院,湖北荆州434023 [4]中国石油西南油气田分公司,四川成都610051 [5]中国石化西南油气分公司,四川成都610016 [6]成都理工大学地球物理学院,四川成都610059

出　　处：《天然气地球科学》2022年第11期1808-1818,共11页Natural Gas Geoscience

基　　金：油气藏地质及开发工程国家重点实验室自由探索基金“扬子板块前陆盆地早期黑色页岩形成的动力学机制及其对页岩气富集的控制作用”(编号:SKL2019015);油气资源与探测国家重点实验室开放基金“典型陆相页岩油甜点成因及评价方法研究”(编号:PRP/open-2104)联合资助.

摘　　要：上扬子地区上奥陶统五峰组—下志留统龙马溪组是中国页岩气勘探开发最成功的层位。开展该套地层黑色页岩高频层序划分,有助于理解有机碳在页岩中的分布特征。以上扬子地区N211井的五峰组—龙马溪组黑色页岩为研究对象,分析了自然伽马(GR)与总有机碳含量(TOC)特征,基于旋回地层学理论划分了黑色页岩高频层序。结果表明:上扬子地区五峰组和龙马溪组下部黑色页岩GR值与TOC值整体上由五峰组底部到五峰组顶部的观音桥段逐渐变大,观音桥段出现极大值,再由观音桥段向龙马溪组逐渐变小。利用GR频谱分析及其滤波曲线,在五峰组和龙马溪组下部分别识别出约6个和7个长偏心率周期,据此,将五峰组和龙马溪组下部划分为12个完整的四级层序和1个不完整的四级层序。该研究可为黑色页岩高频层序划分提供典型案例,并为上扬子地区五峰组—龙马溪组页岩气甜点段预测提供参考,即:在五峰组—龙马溪组页岩高频层序结构中,层序边界附近的黑色页岩有机质富集程度相对较高。The Wufeng-Longmaxi formations in the Upper Yangtze Region are the most successful horizon of shale gas exploration and development in China. The high-frequency sequences division in the Wufeng-Longmaxi formations black shales is helpful to clarify the distribution of organic carbon. The Well N211 black shales were studied to determine Natural Gamma(GR) and total organic carbon content(TOC), and high-frequency sequences were divided based on cyclostratigraphy. The GR value and TOC gradually increase from the bottom of Wufeng Formation to the Guanyinqiao Member(maximum value appears in Guanyinqiao Member), gradually decrease from Guanyinqiao Member to Longmaxi Formation. Using GR spectrum analysis and its filter curve,about six and seven long eccentricity cycles were identified in the Wufeng and lower Longmaxi formations, respectively. The Wufeng and lower Longmaxi formations can be divided into 12 fourth order sequences and one incomplete fourth order sequence. This study can provide a typical case for high-frequency sequences division of black shales, and a reference for shale gas sweet spot prediction in the Wufeng-Longmaxi formations. In the shale high-frequency sequence structure of the Wufeng-Longmaxi formations, the black shales near the sequence boundary are relatively rich in organic matter.

关 键 词：上扬子地区 五峰组—龙马溪组 黑色页岩 高频层序 

分 类 号：P618.13[天文地球—矿床学]