大邑地区须二段物源及沉积相探讨  

Sources and sedimentary facies of the 2nd Member of Xujiahe Formation, Upper Triassic in Dayi area

作　　者：葛忠伟[1] 魏力民[1] 樊莉 张庄[1] 

机构地区：[1]中石化西南油气分公司勘探开发研究院,成都610081 [2]中石油川庆钻探川西钻探公司,成都610051

出　　处：《华南地质与矿产》2013年第1期72-78,共7页Geology and Mineral Resources of South China

基　　金：中石化西南油气分公司科研项目"大邑地区须家河组气水关系与分布预测研究"(编号GJ-118-0904)

摘　　要：大邑地区须二段沉积时期物源体系较四川盆地其他地区简单,且川西南地区须家河组沉积厚度也较盆地其他地区薄。针对现有研究成果有关物源方向存在众多争议的现状,本文从区域沉积背景分析、须家河组野外露头岩性组合特征识别、钻井岩心精细描述、测井相分析、地震反射特征、岩石矿物成分变化等方面入手,认为:①大邑地区及周边区块物源主要来自于盆地西南方,物源区可能为康滇古陆及其周边的古隆起;②研究区须二段处于辫状三角洲前缘环境,有利的储集砂体类型为水下分流河道及河口坝;③受沉积物供应、构造升降运动、以及分流河道频繁迁移的影响,在构造西南翼主要发育水下分流河道,构造主体部位为水下分流河道与河口坝砂体叠置区;④纵向上,两种成因类型的砂体反复叠置,形成了须二段上部连续发育且厚度巨大的砂岩。通过对大邑地区须二段物源及沉积体系的研究,进一步深化了对气藏砂体展布的认识,对今后该区块进一步的勘探具有一定的参考作用。The sources system is less than the other parts of Sichuan basin during deposition of the 2nd member of Xujiahe Formation in Dayi area, and the thickness of Xujiahe Formation is also thinner than others in southwest part of Sichuan basin. Since the controversy of the resources during the existing research, this article analyzed through sedimentary background, lithologic association of outcrop, fine distribution of rock cores, electro-facies, seismic reflection feature and atternation of mineralogical composition, it is believed that：（1）The source is probably the Kangdian ancient land or other palaeohigh around it; （2） It is considered that the depositional environment is in the mouth front braided delta, and the beneficial sandbody include the underwater distributary channels and the bar; （3） Influenced by the amount of sources area, tectonic subsidence, the frequently change of distributary channels, the distributary channels are widely upgrowth in the southwest part of the Dayi structure, and the dis- tributary channels and the mouth bar are overlapped in the main part of the structure; （4） The two types sandbod- ies are frequently overlapped in vertical profile, which formed the continous upgrowth and tremendously sandstone thickness of the 2nd member of Xujiahe Formation. Through the research of sources and sedimentary facies, which deepen the recognition of the sandbody distribution in gas pool, as provided reference for exploration of next phase in this area.

关 键 词：须二段 康滇古陆 辫状三角洲前缘 水下分流河道 河口坝 四川盆地大邑地区 

分 类 号：P588.212[天文地球—岩石学]