松辽盆地姚家组—嫩江组沉积演化与成藏响应

松辽盆地姚家组—嫩江组是一套完整的基准面升降旋回沉积地层,嫩江组二段底部最大湖泛面形成了盆地范围内稳定分布的油页岩,不仅是层序及地层对比的标准界面,而且成为重要的烃源岩层和盖层。姚家组及嫩江组一段是湖进形成的大型湖泊与退积型三角洲沉积,嫩江组二段到五段是强制性水退形成的大型湖泊与进积三角洲沉积;在湖进期嫩江组一段长轴物源方向发育大型重力流水道及末端浊积扇沉积,在嫩江组二段强制性水退环境下进积型三角洲前方发育大型滑塌扇沉积;储集层是湖进-湖退过程中形成的大型三角洲复合体,以分流河道、河口坝及席状砂体为特征,这些砂体向湖盆中心延伸楔入湖相泥岩及成熟烃源岩中,形成良好的生储盖组合关系,特别是盆地长轴物源方向发育的大型三角洲复合体成为油藏集中发育的良好场所,是松辽盆地成为巨型陆相含油气盆地的重要地质条件,同时重力流水道及滑塌扇体也具有形成岩性油气藏的有利条件,是不可忽视的勘探领域。

Depositional evolution and accumulation response of Yaojia-Nenjiang Formation in Songliao Basin

Yaojia-Nenjiang Formation in Songliao Basin is an integrated set of deposit stratum cycle with base level rising and falling.The oil shale distributed steadily in the whole basin were formed during the maximum flooding surface period at the bottom of K2n2.The oil shale is not only the standard interface of sequence and stratigraphic correlation,but also the important source rock and cap rock.Sediments of K2y and K2n1are large-scale lacustrine and retrograded delta deposition formed in the lacustrine transgressive period.Sediments from K2n2to K2n5are large-scale lacustrine and progradation delta deposition formed in the forced lacustrine regressive period.Large-scale turbidite channel and tail turbidite fan were developed in the long axis direction of the material source during the progressive lacustrine period of K2n1.Large-scale slump fan deposition were developed on the top of the progradation delta during the forced lacustrine regressive period of K2n2.The reservoir layer is a complex large-scale delta formed during the transgressive and regressive period,which has the characteristic of the sandbody in distributary channel,mouth bar and sheet sand.The sandbodies extended to the lacustrine center and went into the mudstone and mature source rock,thus formed a good source-reserviorcap relationship.The favorable places for oil pools are mainly developed in the large-scale complex delta in the long axis direction of the material source.It is an important geological condition for megapetroliferous basin with continental facies.The gravity current channel and slump fan are also good conditions for forming the lithological pool,which are very important exploration fields.