四川盆地西北部灯影组深水沉积的发现及油气地质意义  

Discovery of deep-water deposits in Northwest Sichuan Basin during Dengyingian period:Implications for petroleum geology

作　　者：张玺华[1] 彭瀚霖[1] 文龙[1] 李勇[1] 钟佳倚[1] 马奎 罗冰[1] 田兴旺[1] Zhang Xihua;Peng Hanlin;Wen Long;Li Yong;Zhong Jiayi;Ma Kui;Luo Bing;Tian Xingwang(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院

出　　处：《天然气勘探与开发》2020年第4期10-21,共12页Natural Gas Exploration and Development

基　　金：中国石油西南油气田公司科技处项目"德阳—安岳裂陷槽东侧震旦系灯影组油气成藏差异性研究"(编号:20200301-01)。

摘　　要：德阳—安岳台内裂陷作为四川盆地重要控藏地质单元,其成因演化认识上存在较大分歧。通过野外地质研究,发现盆地西北部上震旦统灯影组发育深色泥晶灰岩、白云岩夹薄层硅质岩的深水相沉积,与邻区灯影组巨厚台地边缘微生物丘滩复合体呈巨大岩相差异,揭示了灯影组四段深水盆地相—斜坡相—台缘丘滩相—局限台地相完整相序,进一步明确了灯影期德阳—安岳裂陷的性质,提出晚震旦世盆地西北部地区已具台—盆分异沉积格局,但盆地中部高磨地区裂陷内灯影组发育藻白云岩浅水沉积,裂陷内外地层厚度差异为后期岩溶侵蚀作用结果。结合区域构造背景、地质、地震综合研究提出:①现今德阳—安岳裂陷及周缘灯影组厚度差异是"早期伸展作用下的沉积相分异、桐湾期岩溶侵蚀改造"的地质叠加效应,其性质上具有"北段沉积作用主导,中、南段岩溶侵蚀作用主导"的分段性;②盆地中西部地区灯影组构造分异控制地貌分异,发育深水相沉积及灯二段、灯四段两期巨厚的沉积型台缘带,呈北东走向,而盆地中南部地区灯影组发育侵蚀洼地侵蚀台地,呈近南北向展布;③剖析盆地中西部地区灯影组构造沉积分异作用的油气聚集效应,该区是裂陷中心生烃区、沉积型台缘带的有利叠合区,具有生、储、盖成藏三要素包裹式的耦合特征,有利于灯影组大规模的油气聚集。For Deyang—Anyue intra-platform rift,an important geological unit controlling reservoirs in Sichuan Basin,the cognitions of its formation and evolution are quite different.It is found from field geological research that some deep-water facies deposits of dark argillaceous limestone and dolomite interbedded with thin siliceous rocks are developed in the Upper Sinian Dengying Formation,northwestern basin,representing large lithofacies difference with Dengying Formation in adjacent regions,which is also the microbial mound beach complexes with giant thickness developed at platform margin.A complete facies sequence developed in Dengying 4 Member is revealed,such as deep-water basin facies,slope facies,mound beach facies at platform margin,and restricted platform facies.In addition,the effect of Deyang—Anyue intra-platform rift during Dengyingian period is further made clear.It suggests that the northwestern basin in the late Sinian had a platform-basin differential framework.However,poor tectonic-sedimentary differentiation generated from the rift in Gaoshiti-Moxi area of central basin and formation-thickness variation inside and outside the rift might result in the later karst erosion.According to regional structural setting,and geologic and seismic study,it is proposed that(1)the thickness difference of Dengying Formation in current Deyang—Anyue intra-platform rift and surrounding regions,is the geological superimposition effect of"sedimentary-facies differentiation under early extension and karst erosion transformation during Tongwanian period",which is featured by the segmentation of"sedimentation dominated in the north and karst erosion in the middle and south";(2)the differentiation in the northern basin is obvious,in which deep-water facies deposits are developed inside the rift and two-stage(Dengying 2 and Dengying 4 members)thick sedimentary platform margin zones with NE strike are developed in the rift limb,whereas poor differentiation in the middle and southern basin is affect by apparent karst erosi

关 键 词：四川盆地西北部 晚震旦世 灯影组 德阳—安岳台内裂陷 深水相 沉积型台缘带 构造沉积分异 成藏要素 油气聚集带 

分 类 号：P618.13[天文地球—矿床学]