龙门山前陆盆地南部上三叠统马鞍塘组页岩沉积特征

发布时间：2018-05-31 06:59

  本文选题：前陆盆地 + 马鞍塘组　； 参考：《成都理工大学》2017年硕士论文

【摘要】：龙门山前缘地区油气田(藏)较发育,油气勘探前景较好。龙门山前陆盆地地区多口油气测试分析出马鞍塘组油气潜力巨大,是页岩气储存重要目的层位。通过前人资料收集、野外实测剖面、钻井岩心观察、地球化学分析马鞍塘组页岩沉积特征,马鞍塘组页岩地球化学及储存特征和黑色页岩的形成机制探讨,主要取得了以下的认识;(1)马鞍塘组时期研究区内主要为礁滩相、潮坪-泻湖相沉积,黑色页岩主要是泻湖相沉积。研究区内马鞍塘组下部为浅海生物碎屑灰岩,上部为浅海粉砂岩、泥页岩。马鞍塘组地层厚度在都江堰区域达到200米以上,地层厚度由龙门山向盆地中部逐渐减薄并出现楔形分布。马鞍塘组页岩厚度约为50—120m,在研究区范围内从南到北页岩厚底逐渐增大。(2)马鞍塘组页岩有机碳含量均大于1%,在雅安地区马鞍塘有机碳含量大于2.5。马鞍塘TOC值从西南部的雅安地区向北东方向逐渐的减小,这表明远离龙门山冲断带区域地区逐渐减小。多种类型有机质并存,Ⅲ型、Ⅱ2型和Ⅱ1型都有存在,大部分是Ⅲ型,少部分是Ⅱ2型和Ⅱ1型。马鞍塘组的Ro在雅安地区大于2.0,从西南部的雅安地区向北东方向逐渐的减小,表明远离龙门山冲断地区Ro值逐渐减小。马鞍塘组孔隙度0.5%~1.5%,孔隙度较小。马鞍塘泥页岩渗透率0.001~0.01mD之间,渗透率低。龙门山山前的都江堰-大邑地区富有机质页岩累计有效厚度约100m,平均埋深小于4000m,有机碳含量平均值为2.11%,有机质成熟度至少是1.25%,总含气量至少是1.0m3/t,孔隙度约1.1%,地表以平原和低山为主,保存条件良好,是马鞍塘组页岩气勘探前景区。(3)龙门山前陆盆地富有机质页岩形成机制主要是以下几个方面,其一,卡尼期危机使得古气候从干燥变为湿润,发生了生物大灭绝事件,提高了有机质生产率。巨型季风在晚三叠世早期达到最大,巨型季风带动的洋流在本时期黑色页岩形成过程中为有机质的运移提供了强大动力。位于热带的扬子大陆西缘边缘,巨型季风和上升洋流发育,有机质来源丰富;其二,位于龙门山造山楔-前陆盆地-扬子板块之间,具有封闭的古地貌和缺氧滞留环境;其三,造山带构造负载驱动的挠曲沉降导致前陆盆地具有可容纳空间。
[Abstract]:The oil and gas fields (reservoirs) in the front of Longmen Mountain are relatively developed, and the prospects of oil and gas exploration are good. Multiple oil and gas tests in Longmenshan Foreland Basin show that the Maantang formation has great oil and gas potential and is an important target horizon for shale gas storage. Based on previous data collection, field profile, drilling core observation, geochemical analysis of shale sedimentary characteristics of Maantang formation, shale geochemistry and storage characteristics of Maantang formation, and formation mechanism of black shale, the paper discusses the formation mechanism of black shale in Maantang formation. In the study area of Maantang formation, the reef facies, tidal flat and lagoon facies, and the black shale facies are mainly lagoon facies. In the study area, the lower part of Maantang formation is shallow sea bioclastic limestone, the upper part is shallow siltstone and shale. The formation thickness of Maantang formation is more than 200 meters in Dujiangyan area, and the formation thickness decreases gradually from Longmenshan to the middle of the basin and appears wedge distribution. The shale thickness of the Maantang formation is about 50-120 m, and the thickness base of the shale from south to north increases gradually from south to north. The organic carbon content of the shale in the Maantang formation is more than 1, and the organic carbon content in Maantang is more than 2.5 in Ya'an area. The TOC value of Maantang decreases gradually from the southwest of Ya'an area to the north east direction, which indicates that the area far from Longmen Mountain thrust belt decreases gradually. There are many types of organic matter, such as type 鈪，

本文编号：1958733