Organic Geochemical Characteristics of Source Rocks of Hongshuizhuang Formation in the Mengjiawopu Section of Lingyuan-Ningcheng Basin in North China

摘要

cqvip:Through the regional geological survey,outcrop section measurement and other field geological work,a block of black shale is found at the outcrop of Mengjiawopu Section of Hongshuizhuang Formation in Jixian County,and organic geochemical source rock analysis and evaluation methods are used to study the source rocks in Hongshuizhuang Formation.The set of source rocks is mainly gray-black silty mudstone and gray-black shale,with a cumulative thickness of 78 m;the total organic matter(TOC)is generally high,with an average content of 1.35%,of which good and rich source rock samples account for 86%.A combined analysis of the stable carbon isotope of kerogen,the correlation between Pr/nC17 and Ph/nC18,and the ratio of saturated hydrocarbon to aromatic hydrocarbon identifies that the organic matter is mainly TypeⅡkerogen;the equivalent vitrinite reflectance R o of organic matter is from 1.68%to 1.94%.R c,the correlation of the methylphenanthrene index(MPI)against the vitrinite reflectance is from 1.63%to 1.81%,with an average of 1.71%,and the Odd/Even Predominance(OEP)value is between 0.87 and 1.11,both indicating that the source rocks of the Hongshuizhuang Formation are at the stage of high to over maturation.In summary,the set of source rocks in Hongshuizhuang Formation is characterized by high organic matter content,good kerogen types,and high to over maturation stage.