四川广元上寺剖面上二叠统大隆组有机质分布特征与富集因素

发布时间：2018-05-06 20:42

本文选题：大隆组 + 页岩气　；参考：《地球科学》2017年06期

【摘要】：四川盆地上二叠统大隆组富有机质硅质泥岩是页岩气勘探的一套重要目的层系.利用扫描电子显微镜和元素地球化学等方法探究大隆组有机质类型、分布特征及富集因素,对该地区非常规油气勘探具有指导意义.根据扫描电镜图片,上寺剖面大隆组有机质按形态可分为形态有机质、弥散有机质和沥青.三者成因不同,形态有机质是选择性保存的结果,以离散状分布在所有岩性样品中;弥散有机质是大隆组有机碳总量(total organic carbon,TOC)的主体,主要分布在硅质泥岩样品中,硅质灰岩样品中极少,体现了粘土矿物的吸附作用;沥青是可溶有机质运移进入孔、缝系统,经高热演化后形成的块状有机质,主要分布于硅质灰岩和灰岩样品中.该剖面地球化学数据显示缺氧沉积环境有利于有机质保存,但海洋表层生产力才是控制TOC含量变化的主要因素.研究表明,晚二叠世海平面上升导致上寺剖面大隆组表层生产力增加及底层海水缺氧,该组富有机质黑色硅质泥岩段高TOC是沉积环境与矿物吸附共同作用的结果,同时也反映了原生有机质保存情况.更好的理解泥质烃源岩中有机质赋存类型有助于烃源岩评价及非常规油气勘探开发工作.
[Abstract]:The siliceous mudstone rich in organic matter in the Dalong formation of Upper Permian in Sichuan Basin is an important target series for shale gas exploration. By means of scanning electron microscope and elemental geochemistry, the types, distribution and enrichment factors of organic matter in Dalong formation are studied, which is of great significance for the exploration of unconventional oil and gas in this area. According to the SEM pictures, the organic matter of Dalong formation in Shangsi section can be divided into organic matter form, dispersed organic matter and bitumen according to their morphology. The organic matter forms are the result of selective preservation, distributed in discrete form in all lithologic samples, and dispersed organic matter is the main body of total organic carbon in the Dalong formation, which is mainly distributed in siliceous mudstone samples. There are very few samples of siliceous limestone, which reflect the adsorption of clay minerals, bitumen is the mass organic matter formed by the migration of soluble organic matter into pore and fracture system, which is mainly distributed in the samples of siliceous limestone and limestone. The geochemical data of the section show that the anoxic sedimentary environment is conducive to the preservation of organic matter, but the marine surface productivity is the main factor controlling the change of TOC content. The results show that the rise of sea level in the late Permian resulted in the increase of surface productivity and anoxia in the bottom water of the Dalong formation of Shangsi section. The high TOC of the black siliceous mudstone member rich in organic matter is the result of the interaction of sedimentary environment and mineral adsorption. It also reflects the preservation of primary organic matter. A better understanding of the occurrence types of organic matter in argillaceous source rocks is helpful to the evaluation of hydrocarbon source rocks and the exploration and development of unconventional oil and gas.
【作者单位】：中国地质大学地质过程与矿产资源国家重点实验室;中国地质大学地球科学学院;中国石油化工股份有限公司石油勘探开发研究院;
【基金】：中国地质调查局项目(No.1212011220796) 中国地质大学地质过程与矿产资源国家重点实验室科技部专项经费
【分类号】：P618.13

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