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鄂尔多斯盆地南缘下寒武统高丰度烃源岩 发育特征与油气勘探方向

作    者:黄军平1,2,3, 李相博3, 何文祥1,2, 林俊峰4, 徐耀辉1,2, 包洪平5, 王宏波3, 章贵松3, 完颜容3, 王雅婷3
单    位:1长江大学油气资源与勘探技术教育部重点实验室; 2长江大学资源与环境学院; 3中国石油勘探开发研究院西北分院;4 河南理工大学能源科学与工程学院; 5中国石油长庆油田分公司勘探开发研究院
基金项目:本文受国家科技重大专项下属课题“岩性地层油气藏区带、圈闭评价方法与关键技术”等共同资助
摘    要:
华北板块鄂尔多斯盆地寒武系具有较大勘探潜力。通过对华北板块构造-古地理格局和烃源岩分布特征、生烃能力、生排烃期次与发育模式的研究,明确了鄂尔多斯盆地深层寒武系的勘探潜力并指明下一步有利勘探方向。研究结果表明:①鄂尔多斯盆地南缘下寒武统沉积了一套高丰度优质烃源岩,最厚达80 m,主要为泥页岩,有机碳含量平均值为3.14%,最高达9.19%;干酪根类型以Ⅱ型为主,少量为Ⅰ型;等效镜质组反射率大于2%,处于高—过成熟阶段。②下寒武统烃源岩的发育受构造背景、陆缘斜坡及深水海湾欠补偿环境的共同控制:一方面,早期形成的古地貌背景和深水海湾共同控制着烃源岩的发育规模,使得烃源岩在古凹槽或断陷区、深水海湾区较为发育;另一方面,强还原环境使得烃源岩具有较高的有机质丰度和生烃潜力。③下寒武统烃源岩具有两期生排烃特征,早期大规模生排烃发生于二叠纪末期—中三叠世,此时秦岭尚未大幅度隆升,盆地南缘为一向南倾斜的斜坡;晚期发生于中生代晚期、新生代,在构造活动较弱的富平—洛川海湾和新生代渭河盆地发生了二次生烃。鄂尔多斯盆地南缘庆阳古隆起、富平—洛川海湾两侧的隆起区为油气运移的指向区,具有较大勘探潜力。
关键词:烃源岩; 发育特征; 发育模式; 下寒武统; 鄂尔多斯盆地南缘; 华北板块南缘

Development characteristics of high abundance source rocks of the Lower Cambrian and direction of oil and gas exploration in southern margin of Ordos Basin

Author's Name: HUANG Junping, LI Xiangbo, HE Wenxiang, LIN Junfeng, XU Yaohui, BAO Hongping, WANG Hongbo, ZHANG Guisong, WANYAN Rong, WANG Yating
Institution: 
Abstract:
The Cambrian in Ordos Basin of North China Plate has great exploration potential. Based on the study of North China plate tectonic paleogeographic pattern, source rock distribution characteristics, hydrocarbon generation capacity, hydrocarbon generation and expulsion stages and development model, the exploration potential of deep Cambrian in Ordos Basin is clarified and the next favorable exploration direction is pointed out. The results show that: (1) A set of high abundance and high-quality source rocks (mainly shale) were developed in the Lower Cambrian in southern margin of Ordos Basin, with the thickness up to 80m, with an average organic carbon content of 3.14% and a maximum of 9.19%; the kerogen type is mainly type Ⅱ, with a small amount of typeⅠ; the equivalent vitrinite reflectance is greater than 2%, which is in the high or over mature stage. (2)The development of Lower Cambrian source rocks is jointly controlled by tectonic setting, continental margin slope and deep-water bay of under-compensated environment: on the one hand, the early formed paleogeomorphic background and deep-water bay jointly control the development scale of source rocks, which makes the source rocks more developed in ancient grooves or fault depression areas and deep-water bay areas; on the other hand, the strong reduction environment makes the source rocks have high organic abundance and hydrocarbon generation potential. (3)The source rocks of Lower Cambrian have two stages of hydrocarbon generation and expulsion. In the early stage, large-scale hydrocarbon generation and expulsion occurred in the Late Permian to Middle Triassic, when the Qinling Mountains had not been uplifted significantly, and the south margin of the basin was a southward inclined slope; in the late stage, the secondary hydrocarbon generation occurred in Mesozoic-Cenozoic in Fuping-Luochuan Bay and Weihe Basin developed in Cenozoic with weak tectonic activity. Therefore, the Qingyang paleo-uplift in southern margin of the basin and the uplifted areas on both sides of Fuping-Luochuan Bay are favorable locations for hydrocarbon migration, which have great exploration potential.
Keywords: source rocks; distribution characteristics; development model; Lower Cambrian; southern margin of Ordos Basin; southern margin of North China Plate
投稿时间:2020-12-22  
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