摘要
在充分调研已有成果的基础上,按照Vail经典层序地层理论,综合考虑碳酸盐岩-蒸发岩沉积学原理、台地形态、盆内和古隆起边缘岩性组合特征等,提出了鄂尔多斯盆地奥陶系马家沟组蒸发岩主要赋存于层序下部、浅水碳酸盐岩赋存于层序上部的层序地层划分模式,据此将马家沟组划分为5个三级层序。三级层序界面分别位于马(马家沟组)一段、马三段、马五^(10)亚段、马五^(6)亚段和马五4亚段底部,马家沟组底部和顶部为区域不整合面。在三级层序低位域的时限内,蒸发岩和碳酸盐岩在时空上呈指状交叉,蒸发岩沉积的次数与相邻碳酸盐岩地层中无沉积或间断(不整合)的次数相关,这种四级-五级的沉积间断面是层间溶蚀发育的前提条件,同时也决定了蒸发岩间烃源岩的发育位置。处于低位域的马一段、马三段、马五^(6)亚段3套蒸发岩层系发育潜在烃源岩,主要分布在环盐湖外围洼地及盆地中心斜坡区,具有层薄、累计厚度大的特征。沉积相与多级次层序界面控制储层的发育,主要形成了2类储层:(1)滩相白云岩孔隙型储层,主要发育在三级-四级层序高位体系域中、上部,沉积间断面与滩相叠加区为孔隙型储层发育的有利层位;(2)含膏云岩中膏模溶孔型储层,主要发育在低位体系域的次级海侵期,古隆起边缘区潮坪相带是膏模孔溶蚀型储层发育层位。
Based on the existing research results and the classical sequence stratigraphy theory of Vail P.R.,this study takes into account the sedimentological principle of carbonate-evaporite,platform morphology,and lithological association characteristics of basin interior and margins to propose a sequence stratigraphic division model for the Majiagou Formation in Ordos Basin.According to the model,the sequence,which consists of evaporites mainly at the lower part and shallow water carbonates in the upper part,can be divided into five third-order sequences with boundaries respectively at the bottom of members of Ma1,Ma3,Ma5^(10),Ma^5(6),and Ma5^(4).The bottom and top of Majiagou Formation are regional unconformity surfaces.Within the duration of lowstand systems tract of these third-order sequences,the carbonates and evaporite interfinger each other.The number of the evaporite layers is related to the number of hiatus (unconformity) in the adjacent carbonate sequences.The existence of these 4-5^(th) order hiatus (unconformities) is the prerequisite for the development of interlayer dissolution and determines the location of source rock layers of inter-evaporite.Potential hydrocarbon source rocks are likely to be developed in three evaporative sequences of Ma1,Ma3 and Ma5^(6) members in the lowstand systems tract,which are mainly distributed in the lows surrounding the salt lake and the slope areas of the basin center;moreover,are characterized by thin layers and large accumulated thickness.The sedimentary facies and multiorder sequence boundaries control the development of reservoirs,and two types of reservoirs are mainly formed:(1) The porous dolomitic reservoirs of beach facies are mainly developed in the middle and upper parts of highstand systems tract(HST) of third-to-fourth-order sequence,and the superimposed areas of the sedimentary hiatus and beach facies are the favorable zones for the porous reservoirs.(2) The moldic pore-type gypsodolomite reservoirs are mainly developed during the secondary transgression of t
作者
张涛
张亚雄
金晓辉
周雁
张军涛
谷宁
张威
王濡岳
鲁锴
ZHANG Tao;ZHANG Yaxiong;JIN Xiaohui;ZHOU Yan;ZHANG Juntao;GU Ning;ZHANG Wei;WANG Ruyue;LU Kai(Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206;Petroleum Exploration&Production Research Institute,Hubei Branch of SINOPEC,Zhengzhou,Henan 450006)
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2023年第1期110-124,共15页
Oil & Gas Geology
基金
中国科学院A类战略性先导科技专项(XDA14010406)。
