摘要
近年来,中国陆相盆地页岩油成为油气勘探开发的热点和难点。笔者以柴达木盆地北缘鱼卡地区中侏罗统大煤沟组七段为研究对象,通过岩心、普通薄片观察、有机地化、X衍射等实验,研究了大煤沟组七段的岩相特征、沉积演化模式,为优质烃源岩的发育分布提供理论依据。研究结果表明,该段共发育6种岩相,垂向上可划分为3个沉积阶段。阶段A为温湿气候下的三角洲前缘、浅湖环境,发育贫有机质块状黏土质、硅质泥岩相,强陆源输入导致水体富氧,使该阶段页岩油气潜力较差,TOC平均为0.79%;阶段B为构造沉降作用下半深湖-深湖环境,发育富有机质块状黏土质泥岩相,深湖还原环境为有机质提供了良好保存条件,使该阶段页岩油气潜力较高,TOC平均为4.16%;阶段C为干旱气候、构造沉降共同控制的半深湖-深湖环境,发育富有机质纹层状钙质、富黏土钙质、黏土质泥岩相,湖水咸化分层提供了良好的有机质保存条件,适应性藻类勃发提供了高生产力,使该阶段页岩油气潜力最高,TOC平均为5.03%。
In recent years,shale oil incontinental basins of China has become a hotspot in oil and gas exploration and development.This paper studied the lithofacies characteristics and sedimentary evolution model of the 7th member of Dameigou formation of Middle JurassicinYuqia area,north Qaidam Basin by means of observation of core and thin section,organic geochemistry and X-ray diffraction experiments.It provided theoretical basis for the development and distribution of high-quality source rocks.The results show that there are six types of lithofacies,which can be divided into three sedimentary stagesin the vertical direction.Stage A is the delta front and shallow lake sedimentary environment under warm and humid climate,which develops massive poor-organicclay and siliceous mudstone facies.Strong terrestrial input leads to the oxygen-rich water bodywith an average TOC of 0.79%.Therefore,shale oil and gas potential is poor at this stag.Stage B is a semi-deep to deep lake sedimentary environment under tectonic subsidence,which develops the massive rich organic clay mudstone facies.The deep-lakereducing environment provides good condition for the preservation of organic matter.A higher potential of oil and gas appears with an average TOC of 4.16%.Stage C is a semi-deep to deep lake sedimentary environment jointly controlled by arid climate and tectonic subsidence,which develops the laminar calcareous organic-rich matter,calcareous clay-rich and clayey mudstone facies.Good preservation conditions of organic matter by lake salinity stratification and high productivity of adaptive alga make stage C the highest shale oil and gas potential with an average TOC of 5.03%.
作者
白楠
徐尚
王雨轩
郭天旭
石万忠
BAI Nan;XU Shang;WANG Yuxuan;GUO Tianxu;SHI Wanzhong(Key Laboratory of Structure and Oil-Gas Resources,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;School of Resources,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;School of Geosciences,China University of Petroleum,Qingdao 266580,Shandong,China;Center of Oil&Gas Resource Survey,China Geological Survey,Beijing 100083,China)
出处
《西北地质》
CAS
CSCD
北大核心
2021年第2期74-85,共12页
Northwestern Geology
基金
国家自然科学基金项目(41690134,41821002)
山东省重点研发计划(2020ZLYS08)
中国石油大学(华东)自主创新科研计划(21CX06001A)。
关键词
页岩油
有机质富集
沉积演化模式
大煤沟组七段
柴达木盆地北缘
shale oil
organic enrichment
sedimentary evolution model
the 7th member of Dameigou formation
north of Qaidam basin
