苏北盆地金湖凹陷古近系戴南组孔隙演化及次生孔隙成因分析  

Pore evolution and genesis of secondary pores in the Paleogene Dainan Formation,Jinhu Sag,Subei Basin

作　　者：张琴[1,2] 朱筱敏[1,2] 毛凌 孙祖宇 周琛 苏康 杨立干[4] ZHANG Qin;ZHU Xiaomin;MAO Ling;SUN Zuyu;ZHOU Chen;SU Kang;YANG Ligan(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting(China University of Petroleum(Beijing)),Beijing 102249,China;Geophysical Research Institute,SINOPEC,Nanjing 211103,China;Exploration and Development Research Institute of Jiangsu Oilfield Company,SINOPEC,Yangzhou 225009,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]油气资源与探测国家重点实验室(中国石油大学(北京)),北京102249 [3]中国石化石油物探技术研究院,江苏南京211103 [4]中国石化江苏油田分公司勘探开发研究院,江苏扬州225009

出　　处：《地学前缘》2021年第1期190-201,共12页Earth Science Frontiers

基　　金：国家自然科学基金项目“不同赋存形态海绿石的成因机制及其与储集空间关系研究(41872134)”。

摘　　要：金湖凹陷戴南组储层总体为一套中低孔中低渗碎屑储层,次生孔隙是本区最有效、最重要的孔隙类型,而搞清次生孔隙的分布规律及其成因成为下一步有利储层预测的关键。文中综合利用岩心、普通薄片、铸体薄片、扫描电镜及物性参数等资料,对戴南组储层的岩石类型、物性特征、孔隙类型及次生孔隙分布规律进行了综合分析,并从溶蚀作用的发育条件入手探讨了次生孔隙的成因,以期为下一步有利储层预测和勘探开发提供科学依据。研究认为,金湖凹陷戴南组碎屑岩储层主要发育于三角洲、扇三角洲和滨浅湖,受沉积相带控制,储层类型复杂,以不等粒砂岩、含砾不等粒砂岩、细砂岩及粉砂岩为主,不同地区岩性存在差异。根据岩性三角图,砂岩类型以长石岩屑质石英砂岩为主。砂岩成分成熟度中等偏低,结构成熟度中等。戴南组砂岩孔隙度峰值分布在12.0%~14.0%,渗透率峰值分布在1~10 mD。不同沉积环境和地区储层物性也存在一定差异。三角洲前缘亚相的储层物性最好,平均孔隙度约19.4%,平均渗透率约134.2 mD,岩性以细砂岩为主,主要分布于研究区西部和中部。扇三角洲物性次之,平均孔隙度约12.5%,平均渗透率约6.2 mD,岩性以含砾不等粒砂岩为主,位于桐城断裂带东南部便1井附近。滨浅湖亚相的储层物性最差,岩性以粉砂岩为主,平均孔隙度约8.3%,平均渗透率约2.3 mD。戴南组储层孔隙分为原生孔隙和次生孔隙两大类,以次生粒间溶蚀孔隙为主。溶蚀孔隙包括粒间溶孔、粒内溶孔和铸模孔。粒间溶孔多由粒间碳酸盐胶结物如方解石、白云石、铁方解石等溶蚀后形成,粒内溶孔主要是长石及碳酸盐岩屑被选择性溶解而形成,可见白云石晶粒溶解留下的铸模孔。戴南组储层中的原生孔隙相对较少,主要以石英次生加大后的残余粒间孔的形式存在,发育于埋藏较浅的井�The reservoir of the Dainan Formation,Jinhu Sag is a set of clastic reservoirs with medium-low porosity and permeability.The secondary pore is the most important and effective pore type in the study area,and the determination of its genesis and distribution is the key step for predicting favorable reservoirs.Based on core,thin section and cast thin section data,scanning electron microscope imaging,and physical property measurements,we analyzed the rock type,reservoir property,pore type and distribution of secondary pores,and discussed the genesis of secondary pores in association with the dissolution conditions in this area,which will provide scientific guidance for predicting favorable reservoir and for reservoir exploration.Our study showed that clastic reservoirs mainly deposited in delta,fan delta and show-shallow lakes.Controlled by sedimentary facies,the reservoir rocks are complex and include mainly unequal-grained sandstone and pebbly sandstone,fine sandstone and siltstone,showing varying lithologies in different areas.According to the triangular plot,the sandstone is mainly feldspathic debris quartz sandstone.The compositional maturity is medium to low and the textural maturity is medium.The porosity and permeability peak values were 12.0%14.0%and 110 mD,respectively.There are some differences in reservoir properties associated with different sedimentary facies and regions.The reservoir properties of delta front are most favorable,with an average~19.4%porosity and~134.2 mD permeability,and the lithofacies is mainly fine sandstone distributing in the western and central areas.The fan delta near Well Bian-1 in the southeast of the Tongcheng fault zone cames in second.The fan sandstone is gravel bearing mix-grained sandstone with an average porosity of~12.5%and permeability of~6.2 mD.The reservoir property of shore-shallow lake is least favorable.It deposited mainly siltstone with an average porosity of~8.3%and permeability of~2.3 mD.There are two types of pores,primary and secondary pores,in the Dainan For

关 键 词：孔隙类型 次生孔隙 孔隙演化 控制因素 戴南组 金湖凹陷 

分 类 号：P618.13[天文地球—矿床学]