滨北地区层序地层学研究及岩性圈闭预测

Study on Sequence Stratigraphy and Prediction to Lithologic Traps in Binbei Zone

松辽盆地滨北地区白垩系北部水系在大庆长垣一带形成大型三角洲沉积,三角洲前缘发育了大量的下倾尖灭砂体,部分砂体在后期大庆长垣形成过程中被抬升而由下倾变为上倾,形成岩性圈闭.另一方面基准面变化控制了三角洲位置的迁移,从而决定了三角洲前缘砂体尖灭部位与大庆长垣背斜北坡的相对位置,二者空间位置的搭配影响到砂体上倾尖灭的形成.另外,三角洲前缘的透镜状砂体的圈闭条件由沉积作用决定,不受后期构造运动的影响.基于以上认识,预测大庆长垣以北的黑鱼泡凹陷中嫩一二段的透镜状砂体、大庆长垣北坡姚家组透镜状砂体、滨洲线以南的大庆长垣顶部姚家组上倾尖灭砂体、大庆长垣北坡青山口组透镜状砂体和上倾尖灭砂体是比较有利的岩性圈闭.

The north water system in Binbei zone deposited a large-scale delta near Daqing placanticline during the Cretaceous period. On one hand, at the delta front, there existed lots of sand layers down thinning out, and some of them were distorted from down thinning out to up thinning out by the late rising of Daqing placanticline, so that some lithologic traps were made. On the other hand, the change of base level controlled the delta＇s move,which decided the relative location between thinning out points of sand layers and the north slope of Daqing placanticline. The relative location between them would decide if the sand layers up thinning out were formed or not. In addition, there also existed many lens sand bodies whose trapping conditions were controlled not by tectonic process but by sedimentary process. According to the above, some lithologic traps are predicted. Lens sand bodies in Heiyupao depression on the north of Daqing placanticline in the 1st and 2nd member of Nenjiang formation, lens sand bodies on the north slope of Daqing placanticline in Yaojia formation, sand layers up thinning out at the top of Daqing placanticline in Yaojia formation, sand layers up thinning out and lens sand bodies on the north slope of Daqing placanticline in Qingshankou formation.