摘要
综合利用地球化学、扫描电镜、岩心薄片、测井等资料以及油井生产数据等,对鄂尔多斯盆地陕北地区三叠系延长组7段储层特征、烃源岩特征和致密油分布特征进行了分析,从烃源岩展布、输导体系和源-储组合关系3个方面对致密油差异富集控制因素进行了探讨,并总结了成藏模式。研究结果表明:(1)陕北地区长7段致密砂岩储层主要分布在一亚段(长71)和二亚段(长72),以灰色—灰白色长石砂岩和岩屑长石砂岩为主,长71和长72平均孔隙度分别为5.56%和7.32%,平均渗透率分别为0.097 m D和0.110 m D,长72储层物性更好;孔隙空间以溶孔为主,发育少量粒间孔。(2)研究区烃类主要来源于本地长72顶部和长73这2套烃源岩,平均厚度大于20 m,有机质丰度高,平均TOC值为3.02%,干酪根类型以Ⅰ型和Ⅱ1型为主,处于生烃高峰期,平均生烃量为270.2×10^(4)t/km^(2),长73烃源岩生烃潜力更大,供烃至长72储层,长71致密油来源于长72烃源岩;新安边地区三角洲前缘亚相末端的长72储层中致密油由湖盆烃源岩侧向供烃。(3)研究区致密油富集受烃源岩展布、砂体连通性以及源-储组合共同控制,在长72更富集,在新安边地区分布面积最大,安塞地区无大规模致密油聚集;纵向上和平面上致密油的聚集差异受控于烃源岩厚度和源-储组合关系,下生上储、上下生油而中间储集和砂泥互层时含油性更好;新安边地区三角洲前缘亚相末端的长72致密油聚集规模大于三角洲前缘主体,是由于三角洲前缘末端发育的局部连通砂体阻碍了湖盆烃类物质的侧向运移。(4)研究区致密油为“源控-砂控”成藏模式,远源河道优势砂体尖灭处和近源局部连通的砂体是有利勘探区。
The data of geochemistry,scanning electron microscopy,core thin sections,logging and oil well production were used to analyze the characteristics of reservoirs,source rocks and the distribution of tight oil of the seventh member of Triassic Yanchang Formation(Chang 7 member)in northern Shaanxi area,Ordos Basin,the controlling factors for differential enrichment of tight oil were discussed from three aspects:source rocks distribution,transport system and source-reservoir configuration,and the reservoir accumulation model was summarized.The results show that:(1)The tight sandstone reservoirs of Chang 7 member in northern Shaanxi area are mainly developed in the first sub-member(Chang 71)and the second sub-member(Chang 72),predominantly composed of gray to gray-white feldspar sandstone and lithic feldspar sandstone.The average porosity of Chang 71 and Chang 72 sub-members is 5.56%and 7.32%,respectively,and the average permeability is 0.097 mD and 0.110 mD,respectively.The physical properties of Chang 72 reservoir are better.The pore space is mainly composed of dissolved pores,with a small number of intergranular pores developed.(2)The hydrocarbons in the study area mainly come from two sets of source rocks,including the top of Chang 72and Chang 73,with an average thickness greater than 20 meters.The organic matter abundance is high,with an average total organic carbon(TOC)value of 3.02%.The kerogen types are mainly type I and typeⅡ1,indicating a period of high hydrocarbon generation,and the average hydrocarbon generation amount is 4270.2×10^(4) t/km^(2).Chang 73 source rocks have greater hydrocarbon generation potential,supplying hydrocarbons to Chang 72 reservoir,and the tight oil in Chang 71 comes from Chang 72 source rocks.The tight oil in Chang 72 reservoir at the end of the delta front subfacies in Xin’anbian area is supplied laterally by lake basin source rocks.(3)The enrichment of tight oil in the study area is controlled by the distribution of source rocks,the connectivity of sand bodies and the source-reservoir configuration.It is more enriched in Chang 72and has the largest distribution area in Xin’anbian area,and there is no large-scale tight oil accumulation in Ansai area.The differential tight oil accumulation in the vertical and plane is controlled by the source rock thickness and source-reservoir configuration.The oil-bearing ability is better for lower generation and upper storage,upper-lower generation and middle storage as well as sand and mud interlayers.The scale of tight oil accumulation of Chang 72 at the end of the delta front in Xin’anbian area is larger than that of the main body of the delta front,because the locally connected sand bodies developed at the end of the delta front hinder the lateral migration of hydrocarbon sources in the lake basin.(4)The tight oil in the study area follows a“source-controlled and sand-controlled”accumulation model.The sand bodies in distal river channels and locally connected sand bodies near the source are favorable exploration areas.
作者
牟蜚声
尹相东
胡琮
张海峰
陈世加
代林锋
陆奕帆
MOU Feisheng;YIN Xiangdong;HU Cong;ZHANG Haifeng;CHEN Shijia;DAI Linfeng;LU Yifan(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Sichuan Provincial Key Laboratory of Natural Gas Geology,Southwest Petroleum University,Chengdu 610500,China;Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710004,China)
出处
《岩性油气藏》
CAS
CSCD
北大核心
2024年第4期71-84,共14页
Lithologic Reservoirs
基金
国家自然科学基金“泥质纹层对致密砂岩油藏中构造缝垂向扩展的抑制机理”(编号:42002176)
“源储间泥/钙质等隔层对陆相致密油(低渗透油藏)成藏控制机理研究”(编号:41872165)
“烃源岩早期产物对致密油充注聚集的控制机理研究”(编号:42072185)联合资助。
关键词
致密油
差异聚集
三角洲前缘砂
烃源岩展布
源-储组合
砂体连通性
侧向运移
长7段
三叠系
鄂尔多斯盆地
tight oil
differential accumulation
delta front sand
source rocks distribution
source-reservoir configuration
sand bodies connectivity
lateral migration
Chang 7 member of Yanchang Formation
Triassic
Ordos Basin
