应用沉积学和层序地层学的原理和方法,利用地震、测(录)井、岩芯、露头、古气候及古生物等资料,通过地震合成记录标定,结合盆地区域构造演化特征分析,在松辽盆地北部四方台组—明水组共识别出区域不整合面、古暴露界面、河道侵蚀冲刷面、地层叠加型式转换面4类层序界面,并识别划分出1个新的超层序界面SB4,最终将四方台组—明水组划分为1个超层序组,2个超层序(SSQ1和SSQ2),6个三级层序(SQ1-SQ6),17个体系域,建立高精度层序地层格架。盆地北部层序地层格架内沉积充填演化规律为:层序SQ1~SQ3(SSQ1)沉积时期,盆地主要发育南北向长轴物源的河流及滨浅湖沉积;层序SQ4~SQ6(SSQ2)沉积时期,盆地主要发育东西向短轴物源的辫状河三角洲及滨浅湖沉积;从四方台组时期开始,盆地沉积中心向西北方向不断迁移。根据层序地层格架内的储盖组合分布及成藏条件综合分析可知:纵向上四方台组时期层序SQ1发育本区最有利的储盖组合,而大安—新站地区SQ1低位体系域厚层河床砂岩为本区最有利的油气聚集区带,最有可能形成构造-岩性次生油气藏。
According to seismic, logging, core, outcrop palaeoclimate and palaeontologic data, synthetic seismogram was used to demarcate and analyze the area structure evolution characteristic, and using concept and method of sedimentology and sequence stratigraphy, four types of sequence boundaries were identified, including regional unconformity surface, exposure surface, channel scouring and eroding surface and formation stacking transformation surface, and a new supersequence boundary SB4 was also divided. The results show that Sifangtai to Mingshui formation in the north of Songliao Basin finally can be divided into one supersequence group, two supersequences(SSQ1 and SSQ2), six sequences(SQI-SQ6) and seventy systems tracts and the high resolution sequence stratigraphie framework is also established. The rule of sediment fill and evolution in the sequence stratigraphic framework in the north of the basin is as follows: In the deposition period of sequence SQ1 to SQ3, the basin mainly develops fluvial and coastal-shallow lake facies where provenance's direction is in the direction of SN along the long axis of the basin, while in the deposition period of sequence SQ4 to SQ6, the basin mainly develops braid river delta and costal-shallow lake facies where provenance is in the direction of EW along the short axis of the basin. The basin's deposit center has also constantly migrated to the northwest from the beginning of the Sifangtai formation. Based on the comprehensive research on the reservoir-cap combination distribution of sequence stratigraphy framework and the conditions of the migration, accumulation of oil and gas show that sequence SQI of Sifangtai formation develops the most favorable reservoir-cap combination, and the thick bedded channel sand of the lowstand systems tract of sequence SQ1 in Da'an--Xinzhan area is the most favorable hydrocarbon accumulation area which probably develops structural-lithologic secondary hydrocarbon reservoir.