松辽盆地长岭凹陷隐蔽油气藏勘探研究

应用层序地层学理论, 通过确立各级层序划分标准, 建立了长岭凹陷层序格架, 共划分出8个超层序(二级层序)、35个三级层序.并确定T₁, T₂为最大水泛面(密集段), T₃, T₄, T₄1, T₄2, T_g为超层序界面.对5个时期的沉积体系进行研究, 指明了沉积体形成机制和时空展布特征, 并研究储集体分布特征和含油性.通过层序格架内油气分布规律研究, 发现长岭凹陷油层主要分布在低位体系域.根据试油结果统计油层在低位体系域达48.2 %, 在水进体系域为26.8%, 在高位体系域为25.0 %.从勘探实用角度出发, 以砂体成因为主线, 结合形态分析, 将工作中见到的岩性圈闭和复合圈闭分为4类: 河道砂体、前积朵叶砂体、断层-岩性、构造-岩性.总结出一套隐蔽油气藏勘探工作方法和流程.最后, 对松辽盆地长岭凹陷隐蔽油气藏分布进行了预测, 并提出勘探部署意见. 

Study of Subtle Oil/Gas Reservoirs Exploration in Changling Sag of Songliao Basin

By using the theory of sequence stratigraphy, this paper establishes a standard for sequence classification and sequence framework in Changling sag, Songliao basin. Accordingly, we distinguish eight supersequences (second-order sequence) and thirty-five third-order sequences. T_1 and T_2 were recognized to be mfs (condensed section), and T_3, T_4, T1_4, T2_4 and T_g to be supersequence bounding surfaces. The study of the sedimentary systems formed in these five periods revealed the formation mechanism and spatial distribution of sedimentary bodies. Meanwhile, we also studied the distribution and oil-bearing characteristics of sedimentary reservoirs. On the basis of the study of oil/gas distribution in the sequence framework, we found that oil-/gas-bearing beds are mainly distributed in lowstand systems tract. The statistical study of well testing results shows that 48.2% of oil beds are in lowstand systems tract, 26.8% in trangressive systems tract (TST) and 25.0% in highstand systems tract. For the exploration purpose, the encountered lithologic traps and polygenesis traps are divided into four types: river course stone, frontal sedimentary leafy sand body, fault-lithology and structure-lithology sand body. Hence, this paper draws up the method for subtle reservoir exploration and finally makes the prediction of the subtle oil/gas reservoirs and the suggestions for the exploration plan in Changling sag.