摘要
西湖凹陷平湖组发育海陆过渡沉积体系,以砂、泥、煤薄互层为特征,砂体成藏条件优越,逐步成为隐蔽油气藏滚动挖潜的热点。但由于其埋深大、砂体薄、横向变化快,使得砂体预测难度大、精度低。利用稳定煤层对高频层序格架搭建的指示作用,建立了含煤地层高频层序格架;在煤层等时格架约束下,基于地震沉积学的地层切片技术对不同层位砂体沉积特征进行了深入分析。研究结果表明:平湖组一、二段划分为2个三级层序、7个四级层序;储层类型主要包括分流河道、决口扇、三角洲、潮道4种,分流河道宽500~1 000 m、厚10~40 m、宽厚比12∶1~40∶1,决口扇平面规模1~10 km2、内扇厚5~10 m,三角洲平面规模15~200 km^2,潮道宽度仅80~360 m、厚2~5 m;垂向演化主要受控于海平面变化、物源供给和古地貌形态,指出Sq2海退序列发育的分流河道及其伴生决口扇砂体成藏耦合关系良好,是下一步实施周边隐蔽油气藏挖潜的方向之一。
Pinghu Formation of the Xihu sag developed sea-land transition sedimentary systems with the characteristic of thin interbedding among sand,clay and coal layers.The accumulation conditions of narrow thin sand body are superior,which gradually become the hotspot of rolling exploration and development.To determine the genetic type of narrow thin sand body,plane size,evolution rules and main control factors,the indication function of stable coal seam to high frequency sequence formation was fully used to set up their constructions based on the analysis of core,logging and seismic data,and the sedimentary characteristics were studied intensively by using seismic sedimentology strata slice technology.Firstly,a high frequency sequence framework of coal-bearing strata was established,and the one and second segment of Pinghu formation was divided into two third-order sequences and seven fourth-order sequences.Secondly,three kinds of narrow thin sandstone geneses were identified as distributary channel,flood fan and tidal channel.The width of distributary channel was from 500 m to 1 000 m,the plane size of flood fan was from 1 km 2 to 10 km 2,both of which were developed in regressive sequence,however,the tidal channel width was only from 80 m to 360 m,and developed much more in transgressive sequence.Finally,the vertical evolution and main controlling factors of narrow thin sand body were discussed and pointed out that the distributary channel and its associated flood fan sand body had good accumulation coupling relationship in the regressive sequence,which should be the main direction of subtle reservoir exploration.
作者
刘英辉
黄导武
段冬平
陈波
丁芳
陈晨
黎祺
LIU YingHui;HUANG DaoWu;DUAN DongPing;CHEN Bo;DING Fang;CHEN Chen;LI Qi(Shanghai Branch of CNOOC Ltd.,Shanghai 200335,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2018年第5期957-968,共12页
Acta Sedimentologica Sinica
基金
国家科技重大专项(2016ZX05027-004)~~
关键词
地震沉积学
含煤地层
中深层
定量解剖
平湖组
西湖凹陷
seismic sedimentology
coal-bearing strata
middle-deep sand body
quantitative anatomy
Pinghu Formation
Xihu sag
