四川盆地东部地区寒武系膏盐岩厚度定量预测及其油气地质意义  

Quantitative thickness prediction of Cambrian gypsum-salt rocks in eastern Sichuan Basin and its petroleum significance

作　　者：江青春[1] 李建忠[1,2] 汪泽成 黄士鹏[1] 苏旺[1] 姜华[1] 曾富英[1] 鲁卫华[1] 毕赫[1] JIANG Qingchun;LI Jianzhong;WANG Zecheng;HUANG Shipeng;SU Wang;JIANG Hua;ZENG Fuying;LU Weihua;BI He(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;PetroChina Tuha Oilfield Company,Hami,Xinjiang 839000,China)

机构地区：[1]中国石油勘探开发研究院,北京市100083 [2]中国石油吐哈油田公司

出　　处：《天然气工业》2022年第5期34-46,共13页Natural Gas Industry

基　　金：中国石油前瞻性基础性科技攻关项目“深层超深层油气成藏过程与油气分布规律研究”(编号:2021DJ0203)。

摘　　要：膏盐岩为盖层的油气藏在全球大型油气藏中所占的比例极高。四川盆地东部地区(以下简称川东地区)寒武系膏盐岩层分布广泛,但厚度不均匀,受川东地区构造变形程度高、二维地震资料品质较差等因素的影响,地球物理技术预测膏盐岩厚度难度极大。为此,在寒武系膏盐岩沉积模式研究的基础上,利用正演模型建立了不同膏盐岩层岩性组合地震识别模式,并应用相控校正系数法预测了川东地区寒武系膏盐岩的厚度分布,最后结合勘探成果指出了该区的油气勘探方向。研究结果表明:①寒武系膏盐岩岩性组合可划分为4种类型,分别为无膏盐岩组合型、薄层膏盐岩组合型、互层膏盐岩组合型和厚层膏盐岩组合型;②建立了4种岩性组合类型所对应的地震正演模型,结合平面插值的方法,定量落实了各种岩性组合的平面分布特征;③依据不同岩性组合类型中膏盐岩厚度和地层厚度的比例关系,确定了不同岩性组类型的膏盐岩厚度校正系数,并预测了膏盐岩平面厚度分布。结论认为,①川东地区寒武系膏盐岩层具有自北西向南东逐渐增厚的特征,其中膏盐岩中心主要发育在建深1井区和太和1井区;②膏盐岩盖层之下的寒武系—震旦系地层,可能是未来深层常规及非常规天然气勘探的重要领域;③围绕膏岩湖盆中心边缘的古地貌高部位是寒武系龙王庙—高台组颗粒滩储层发育的有利区。The proportion of oil and gas reservoirs with gypsum-salt rocks as caprocks in global large-scale oil and gas reservoirs is quite high.Cambrian gypsum-salt rock layers are widely distributed in the eastern Sichuan Basin,but their thickness is not uniform.The degree of structural deformation in the eastern Sichuan Basin is high,and the quality of two-dimensional seismic data is poor,which makes it very difficult to apply geophysical technologies to predict gypsum-salt rock thickness.After studying the sedimentation model of Cambrian gypsum-salt rocks,this paper establishes seismic recognition models of different lithology combinations in gypsum-salt rock layers using forward model.Then,thickness distribution of Cambrian gypsum-salt rocks in the eastern Sichuan Basin is predicted using the facies-control correction coefficient method.Finally,the oil and gas exploration direction in this area is pointed out on the basis of exploration achievements.And the following research results are obtained.First,the lithology combinations of Cambrian gypsum-salt rocks can be classified into four types,i.e.,gypsum-salt rock free combination,thin gypsum-salt rock combination,interbedded gypsum-salt rock combination and thick gypsum-salt rock combination.Second,seismic forward models corresponding to four lithology combinations are established,and combined with the plane interpolation method,the plane distribution characteristics of each lithology combination are confirmed quantitatively.Third,the gypsum-salt rock thickness correction coefficient of different types of lithology combinations is determined based on the ratio of gypsum-salt rock thickness to formation thickness,and the plane thickness distribution of gypsum-salt rocks is predicted.In conclusion,Cambrian gypsum-salt rocks in the eastern Sichuan Basin get thicker gradually from northwest to southeast and the center is mainly developed in Well Block JS1 and Th1.What's more,the Cambrian-Sinian below the caprocks of gypsum-salt rock may be an important field of deep conve

关 键 词：四川盆地 川东地区 寒武系 膏盐岩层 相控校正系数 厚度预测 盖层 勘探方向 

分 类 号：P618.13[天文地球—矿床学]