松辽盆地中部含油组合高精度层序地层格架分析

上白垩统青山口组、姚家组和嫩江组一段是松辽盆地最主要的含油层系,习惯上称之为中部含油组合。地震、测井、录井、岩芯及古生物资料综合研究表明,中部含油组合由超层序SSQq-qn的高水位时期和湖泊萎缩时期形成的青山口组二三段和SSQy-n的低水位时期和湖泊扩张时期形成的姚家组和嫩江组一段组成。中部含油组合内部的姚家组底界为超层序界面,其顶底分别为超层序SSQq-qn和SSQy-n的密集段。中央坳陷区中部含油组合发育的地层较全。青一段和泉头组四段顶部组成1个三级层序,包含2个四级层序;青二三段由3个三级层序构成,又可划分为5个四级层序;姚家组由2个三级层序组成,并分别对应1个四级层序;嫩江组一段相当于1个三级层序,其中可划分为3个四级层序。不同级别的层序在古生物、岩性—测井曲线和地震反射资料上都有特征的响应。

HIGH-RESOLUTION SEQUENCE STRATIGRAPHIC FRAMEWORK FOR THE MIDDLE OIL-BEARING BEDS IN THE SONGLIAO BASIN

Strata from the Qingshankou Formation to the 1 st member of the Nenjiang Formation of the Upper Cretaceous are the main oil-bearing rocks in the Songliao Basin.They are collectively known as middle oil-bearing beds.This research,built upon seismic,log,core and paleontological data,shows that the middle oil-bearing beds consist of the 2 nd and 3 rd members of the Qingshankou Formation,the Yaojia Formation,and the 1 st member of the Nenjing Formation.The 2 nd and 3 rd members of the Qingshankou Formation were deposited in the upper part of the supersequence SSQq-qn during lacustrine contraction times.The Yaojia Formation and the 1 st member of the Nenjing Formation are deposited in the lower part of SSQy-n during lacustrine expansion times.The middle oil-bearing beds are well-developed in the central depression area.The 1 st member of the Qingshankou Formation and the 4 th member of the Quantou Formation from a 3-order sequence,and consist of two 4 th-order sequences.The 2 nd and 3 rd members of the Qingshankou Formation consist of three 3 rd-order sequences and five 4 th-order sequences.The Yaojia Formation is composed of two 3 rd-order sequences,each of which includes one 4 th-order sequence.The 1 st member of the Nenjiang Formation corresponds to one 3 rd-order sequence and can be divided into three 4 th-order sequences.These sequences are characterized by distinct paleontological,lithostratigraphic-logging and seismic reflection data.