对大川中地区上三叠统须家河组二、四、六段砂岩沉积相的再认识  

A new understanding of sedimentary facies of sandstones in the 2^(nd),4^(th),and 6^(th) members of the Upper Triassic Xujiahe Formation in the Large-Scale Middle Sichuan Basin

作　　者：蒋裕强[1] 陶艳忠[1] 沈妍斐[1] 蒋婵[1] 王占磊[1] 张本健[2] 李顺[3] 张国常[4] 

机构地区：[1]西南石油大学资源与环境学院 [2]中国石油西南油气田公司川西北气矿 [3]中国石油西南油气田公司川中油气矿 [4]中国石化勘探南方分公司

出　　处：《天然气工业》2011年第9期39-50,134-135,共12页Natural Gas Industry

基　　金：国家科技重大专项"2011ZX05001-005-002"的部分研究成果

摘　　要：学界对四川盆地晚三叠世须家河期沉积相的认识一直存在较大分歧,观点颇多。为此,基于露头剖面观察、取心井精细描述、单井剖面分析、实验室薄片鉴定,结合大量测井资料的研究应用成果,综合研究后认为:四川盆地大川中地区须二段砂体为滨浅湖砂体,河流相砂体分布在龙岗—旺苍以北、广安以东的区域,川中西部—川西北部地区有海侵影响,形成质纯的石英砂岩;须四段、须六段沉积期,除营山—八角场、广安—河包场地区须四段及须六段下部发育三角洲分支河道外,其余大部分地区为河流入湖砂体在湖岸线不断进退、湖面总体扩张的背景下经湖流、波浪再改造、再分配形成的滨浅湖滩坝砂体。结论表明:①在川中南部地区由于受雷口坡期古凸起的影响,在该凸起区缺失须一—须二段下部地层;②受湖流运动方向影响,湖盆中的砂体在川中南部地区呈北东向展布,而在川中北部地区则呈近东西向展布;③滩坝砂体主体分布区是优质孔隙性储层的发育区。There are strong disagreements in the academic circle as to such understandings of the late Triassic channel facies in the Xujiahe Formation of the Sichuan Basin.In view of this,this paper conducts a deep investigation in this study area into the outcrop profile observation,fine description of logging from cored wells,per-well profile analysis,and chips identification at laboratory.On the basis of this and in combination with research results from a number of logging data,this paper concludes that shore-shallow lake facies dominate the sand bodies in the 2nd member of the Xujiahe Formation while fluvial facies of sand bodies are mainly distributed in the areas to the north of Longgang-Wangcang and to the east of Guang'an.The influence of marine transgression can be shown from the pure quality quartz sandstone in the areas of the western Middle Sichuan Basin and the northwestern Sichuan Basin.In the sedimentary period,apart from the well-developed delta branch channels in the lower 4th and 6th members of the Xujiahe Formation of the Yingshan-Bajiaochang and Guang'an-Hebaochang areas,the channel sand bodies in most other areas advanced and retreated along the lake shoreline,and after being reformed and re-distributed by currents and waves,the shore-shallow lake facies came into being in the end.The following conclusions are achieved in this study.(1)Influenced by the paleo-uplift in the Leikoupo period,the lower beds in the 1st and 2nd members of the Xujiahe Formation are absent in the southern study area.(2)Influenced by the direction of lake currents,the sand bodies in the lake basin are in the N-E trending distribution in the southern study area,while those in nearly E-W trending distribution in the northern study area.(3)The quality porous formations are well developed in the area dominated by the shoal-bar sand bodies.

关 键 词：四川盆地中部 晚三叠世 沉积相 新认识 河道砂体 滨浅湖滩坝砂体 海侵 优质储集层分布 

分 类 号：P618.13[天文地球—矿床学] P512.2[天文地球—地质学]