四川盆地高石梯—磨溪区块灯四段沉积相变对岩溶储层发育影响  

Effects of sedimentary facies change on development of karst reservoirs in Dengying 4 Member, Gaoshiti-Moxi Block, Sichuan Basin

作　　者：朱讯[1] 徐伟[1] 李菡韵 刘义成[1] 鲁杰[1] 陶夏妍 申艳[1] 张旋[1] Zhu Xun;Xu Wei;Li Hanyun;Liu Yicheng;Lu Jie;Tao Xiayan;Shen Yan;Zhang Xuan(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》2018年第3期51-57,共7页Natural Gas Exploration and Development

基　　金：国家科技重大专项课题"大型油气田及煤层气开发"(编号:2016ZX05052)

摘　　要：四川盆地高石梯—磨溪区块震旦系灯四段气藏为受风化壳古地貌控制的大型碳酸盐岩古岩溶气藏,丘、滩相主要发育于台缘带,地震预测储层大面积连片发育。但是近期部署在磨溪区块台缘带的几口探井相继失利,为寻找其失利原因,在区域构造沉积演化研究成果的基础上,通过井震结合,重点刻画灯四段沉积相相变,分析相变对后期风化壳岩溶及岩溶储层发育的影响。结果表明:(1)研究区受桐湾Ⅰ幕形成的剥蚀面影响,台缘带内存在丘滩体与滩间海沉积的相变;(2)在相对隆起区域灯四段丘滩体继承性发育;在相对低洼区域,灯四段以填平补齐沉积为主,主要为滩间海沉积微相,不利于丘滩体发育。结论认为:沉积微相变化控制了研究区台缘带岩溶储层展布,在滩间海沉积微相区域,岩性致密,裂缝欠发育,不利于后期岩溶改造(岩溶储层厚度一般小于10 m);在丘滩体发育区域的相对隆起部位,裂缝发育,有利于后期风化壳岩溶的形成,同时岩性主要为富藻白云岩,有利于表生岩溶溶蚀孔洞保存(岩溶储层厚度介于25~50 m)。The Sinian Dengying 4 Member,Gaoshiti-Moxi block,Sichuan Basin,is large-scale palaeokarstic gas reservoirs controlled by weathering-crust palaeogeomorphology.Bioherm and beach facies are mainly developed along platform marginal belts.And it is predicted from seismic data that these reservoirs are developed continuously and extensively.However,several exploration wells deployed along the platform margin in Moxi block have recently suffered failure one after another.So,some research results on the sedimentation and evolution of regional structures were reviewed.Moreover,by virtue of well-seismic integration,the sedimentary-facies change of Dengying 4 Member was analyzed.And the effects of facies change on development of weathering-crust karst and karst reservoirs were summarized.Results show that(1)affected by denudation surface formed during Tongwanian I period,there is a facies transition from bioherm and beach to interbank sea inside the platform margin;and(2)for some higher areas,both bioherm and beach faceis are dominantly developed in Dengying 4 Member whereas filling and compensation deposits are dominant for other lower areas,which the main facies of interbank sea are unfavorable for the development of bioherm and beach.It is deemed that,the distribution of karst reservoirs along the platform margin is controlled by microfacies change.In some areas of interbank sea microfacies,tight lithology and underdeveloped fractures are not advantageous to the later karst reconstruction(karst reservoirs are generally less than 10 m in thickness).In other higher zones developed by bioherm and beach facies,well-developed fractures are conducive to the development of later weathering-crust karst;and dolomites with rich algae are also favorable for preserving dissolved pores among epigenetic karst(karst reservoirs are generally 25～50 m in thickness).

关 键 词：白云岩 相变 丘滩体 岩溶储层 晚震旦世 四川盆地 

分 类 号：P618.13[天文地球—矿床学]