扶新隆起带泉头组层序地层格架及发育模式

Sequence stratigraphic framework and development model of Quantou Formation in Fuxin Uplift in Songliao Basin

松辽盆地扶新隆起带泉头组存在层序地层划分方法不统一、各油田间地层划分方案混乱、对泉头组整体研究不足等问题,极大地影响了油气勘探开发的效果。文中运用基准面旋回层序地层学原理,综合利用岩心、录井、地震等资料,通过进积-退积作用转换面、河道冲刷面的识别,以及地层叠置样式变化的研究,划分了扶新隆起带北坡泉头组各级基准面旋回界面,建立了全区高分辨率层序地层格架。研究表明:泉头组整体上发育6个半长期基准面旋回,其中泉三、泉四段发育10个中期基准面旋回,30个短期基准面旋回。泉三、泉四段短期基准面旋回样式共分为三大类7个亚类。研究区泉头组经历了多期长期基准面升降变化,沉积环境自下而上出现河流—滨浅湖—三角洲—河流—三角洲的变化。

Problems such as inconsistent method of sequence stratigraphic division, confusion of stratigraphic division schemes among oilfields, and insufficient study of Quantou Formation as a whole greatly restricts the effect of further oil and gas exploration and development. Based on the principle of base-level cycle sequence stratigraphy, using core, mud logging, seismic and fossil data, and recognizing the change of progradational-retrograde conversion surface, channel scouring surface and stratigraphic superimposition patterns, base-level cycles are divided at all levels of Quantou Formation in the northern slope of Fuxin Uplift, and the high-resolution sequence stratigraphic framework is established. Research results show that the Quantou Formation has developed six and a half long-term base-level cycles on the whole, including ten medium-term and thirty short-term base-level cycles in the 3rd and 4th members of Quantou Formation. The short-term base-level cycles of the 3rd and 4th members of Quantou Formation are divided into three basic types and seven subtypes. The Quantou Formation in the study area has undergone many periods of long-term base-level rise and fall, and the sedimentary environment has changed from bottom to top from river to shallow lake to delta to river to delta.