摘要
四川盆地川西坳陷泥盆系具有发育大型油气藏的成藏条件,但由于泥盆系埋藏深度大、研究程度低,其分布状况长期存疑。近期,在川西坳陷中部二叠系底与寒武系底之间新发现了一个角度不整合面,因资料限制,不能直接确认该不整合面的地质属性。为此,以该角度不整合面为研究对象,依据地表露头、钻井、区域构造演化、川西坳陷北部泥盆系—石炭系残余地层分布以及沉积相等资料,分析推断该不整合面的地质属性;详细对比、追踪该不整合面,研究泥盆系—石炭系残余地层的分布,编制二叠纪前古地质图;结合加里东秦祁洋的演化历史,探讨断陷槽的形成机理;进而依据礁滩地震相特征,预测该区泥盆系—石炭系的油气勘探前景。研究结果表明:①该不整合面可能为泥盆系的底界面,主要分布于文星—中江—绵阳老关庙一带,其上为泥盆系—石炭系残余地层;②泥盆系—石炭系残余地层呈现出断陷槽的特征,并且存在着多个断陷;③断陷槽可能为秦祁洋在奥陶纪—石炭纪期间扩展,于龙门山裂谷内形成的次级断陷;④以川西断陷槽为中心,泥盆系—石炭系礁滩相在其两侧对称分布,规模大、礁滩相特征明显。结论认为,川西坳陷泥盆系—石炭系发育礁滩相,其上叠置二叠系礁滩相,下伏寒武系生烃中心,具有多层系立体勘探的有利条件和良好的油气勘探前景。
The Devonian in the West Sichuan Depression of the Sichuan basin has the conditions for the formation of large oil and gas reservoirs. Due to its great burial depth and low research degree, however, its distribution situation has been suspected for a long time. Recently, an angular unconformity is newly discovered between the Permian bottom and the Cambrian bottom in the central area of West Sichuan Depression, but its geological properties cannot be defined directly due to limited data. In this paper, the geological properties of this newly discovered angular unconformity were analyzed and inferred based on the data of surface outcrop, drilling, regional tectonic evolution, distribution of Devonian-Carboniferous residual strata in the northern area of the West Sichuan Depression and sedimentary facies. Then, this unconformity was compared and traced in detail, the distribution of the Devonian-Carboniferous residual strata was studied, and the Pre-Permian paleogeological map was prepared. Finally, the formation mechanism of rift trough was discussed based on the evolution history of Qinqi ocean in the Caledonian period. What’s more, the oil and gas exploration prospect of Devonian-Carboniferous in this area was predicted based on the seismic facies characteristics of reef flat. And the following research results were obtained. First, this unconformity may be the bottom boundary of the Devonian, and it is overlain by the Devonian-Carboniferous residual strata. It is mainly distributed in the Wenxing-Zhongjiang-Mianyang-Laoguanmiao area. Second, the Devonian-Carboniferous residual strata present the characteristics of rift trough, and there are many rifts. Third, the rift trough may be the extension of Qinqi ocean during the Ordovician-Carboniferous and evolves into the secondary rift in Longmenshan rift valley. Fourth, with the West Sichuan rift trough as the center, the Devonian-Carboniferous reef flat facies is symmetrically distributed on both sides. The scale is large and the characteristics of reef flat fac
作者
刘殊
王浩
吕其彪
董霞
刘红爱
孙玮
LIU Shu;WANG Hao;LYU Qibiao;DONG Xia;LIU Hong'ai;SUN Wei(Sinopec Southwest Oil&Gas Company,Chengdu,Sichuan 610200,China;State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation//Chengdu University of Technology,Chengdu,Sichuan 610059,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2020年第9期1-10,共10页
Natural Gas Industry
基金
中国石化西南油气分公司科研项目“川西北海相上组合油气远景评价及目标优选”(编号:KTS-118-1916)。
关键词
四川盆地
川西坳陷中部
断陷槽
泥盆纪—石炭纪
礁滩相
不整合面
多层系立体勘探
油气勘探前景
Sichuan basin
Central area of West Sichuan Depression
Rift trough
Devonian-Carboniferous
Reef flat facies
Unconformity
Multi-layer 3D exploration
Oil and gas exploration prospect
