羌塘盆地上三叠统和下侏罗统有机地球化学特征及烃源岩评价

发布时间：2018-04-10 18:24

本文选题：TOC + 烃源岩评价　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：羌塘盆地上三叠统和下侏罗统地层是青藏高原最具生烃潜力的地层,但前期勘探程度较低,前人有机地球化学研究主要依据地表遭受不同风化作用生物露头样品。本文对上三叠统(QK-2孔)和下侏罗统(QK-3孔)地层从有机地球化学特征、沉积环境和岩相古地理三个方面对研究地层进行烃源岩评价,进而为羌塘盆地油气包括水合物勘查提供来自钻井的地质基础资料。上三叠统肖茶卡组主要为一套砂和粉砂碎屑岩,不含厚层暗色泥岩;有5个单层含粉砂泥岩厚度达到1m以上的层段;下侏罗统曲色组存在4段暗色泥岩层,单层暗色泥岩最大厚层达11.36m。获得了两套地层的有机地球化学记录。上三叠统TOC含量平均值为0.75%,有8段达到中等烃源岩及以上级别。TOC丰度类型系数低(24、10),属腐泥腐殖型(II2),高镜质体反射率(平均Ro=0.98%)指示烃源岩处于成熟阶段。下侏罗统TOC含量平均值4.20%,丰度极好(类型系数为45、42),为腐殖腐泥型(II1),Ro平均值0.51%,处于未成熟-低成熟阶段。初步分析了两套烃源岩的沉积环境。上三叠统和下侏罗统烃源岩沉积时期间搬运距离较近,但是前者比后者物源供给充分,沉积速度较快。利用沉积物地球化学环境指标初步探讨了晚三叠世和早侏罗世期间气候等沉积环境。综合初步评价,研究区上三叠统肖茶卡组为差-中等烃源岩;而下侏罗统曲色组为有利的烃源岩。
[Abstract]:The Upper Triassic and Lower Jurassic strata in Qiangtang Basin are the most hydrocarbon generating strata in the Qinghai-Tibet Plateau, but the exploration degree in the early stage is relatively low. Previous organic geochemical studies are mainly based on different weathering biological outcrop samples on the surface of the Qinghai-Xizang Plateau.The source rocks of the upper Triassic (QK-2) and the Lower Jurassic (QK-3) strata are evaluated from three aspects: organic geochemical characteristics, sedimentary environment and lithofacies paleogeography.The geological data from drilling are provided for oil and gas exploration including hydrate exploration in Qiangtang Basin.The Shaocha Ka formation of the Upper Triassic is mainly composed of a set of sand and silt clastic rocks without thick layer dark mudstone, five single-layer silty mudstone formations with thickness of more than 1m, and four dark mudstone formations in the Lower Jurassic meandering formation.The maximum thickness of single layer dark mudstone is 11.36 m.Two sets of organic geochemical records were obtained.The average TOC content of the Upper Triassic is 0.75, and there are 8 members with medium source rocks and above. The low TOC abundance type coefficient is 240.10g, which belongs to the humic saprophyte type II2G. The high vitrinite reflectance (average Ro-0.98) indicates that the source rocks are in the mature stage.The average value of TOC content in Lower Jurassic is 4.20 and its abundance is excellent (type coefficient is 45 ~ 42g). The average value of Ro of humic saprophyte is 0.51%, which is in the immature to low mature stage.The sedimentary environment of two sets of source rocks is preliminarily analyzed.The source rocks of the Upper Triassic and Lower Jurassic are transported more closely during the sedimentary period, but the former is more abundant than the latter, and the deposition rate is faster than that of the latter.The climate and other sedimentary environments during the late Triassic and early Jurassic were preliminarily discussed by using the geochemical environmental indicators of sediments.The preliminary evaluation shows that the upper Triassic Xiaocha Ka formation is a poor to medium source rock, while the lower Jurassic meandering formation is a favorable source rock.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13;P534.3

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