海拉尔盆地乌尔逊-贝尔坳陷隆起带类型及对油气成藏控制作用

海拉尔盆地为典型的小型断陷湖盆,具有"下断上凹"的二元结构,"洼槽控油、隆起带控油"特征明显。本文在系统研究构造演化特征的基础上,分析了不同类型隆起带形成演化历史及对油气的控制作用。研究表明,海拉尔盆地构造演化历经了5个阶段:即铜钵庙组山间盆地、南一段和南二段被动裂陷盆地、南三段和南四段主动裂陷盆地、大磨拐河组-伊敏组断-坳转化盆地和青元岗组坳陷盆地。经历了3期强烈变形和2期强烈改造,被动裂陷的走滑作用导致反向断层及其下盘翘倾隆起,形成"长期淋滤造储、近洼不整合输导、反向断层遮挡" 的成藏有利条件,最终成为被动裂陷层序有利油气富集区带。主动裂陷伸展作用形成小型滚动背斜和中央隆起带,小型滚动背斜带形成"小而肥"构造油藏,而中央隆起带形成典型的复式油气聚集带。南屯组沉积末期构造反转,导致部分中央背斜带隆升剥蚀,断裂切割破碎,进而导致大气水下渗淋滤,有效改造基岩潜山储层,成为基岩潜山油藏的富集带。伊敏组沉积末期,形成正反转断层和反转期活动的正断层两种调整型断层,将早期聚集在断陷构造层的油气调整到大磨拐河组,聚集在反转构造及其边部,形成次生油气聚集带。

The type of uplift zones and its control for hydrocarbon accumulation in the Wuerxun-Beier depression, Hailar Basin

Hailaer Basin is a small rift lake basin,featured by structure of "bottom rift,upper sag" and "sub-sag and uplift belt-control oil".Basis on the research of characteristics of structural evolution,the formation and evolution history of different uplift belt and the control of uplift belt on hydrocarbon reservoir was analyzed.The study suggests that the evolution of Hailaer Basin went through five stages,intermountain basin of Tongbomiao Formation,Passive rift basin of Member K₁n¹ and K₁n²,initiative rift basin of member K₁n³ and K₁n⁴,rift-depression basin of Damoguai-Yimin Formation and depression basin of Qingyuangang Formation.Under heavily 3 periods deformation and 2 periods alteration,strike-slip movement of passive rift basin generate backward faults and tilt-uplift of footwall.Reservoir-forming conditions of this area feature by "leaching-made reservoir,unconformity of sag transporting,sealed by backward faults",which is the favorable areas for reservoir.Extension of initiative rift generate small scroll anticline and central uplift belt,the former developed several small and rich structural reservoirs,and the latter developed composite oil-gas accumulation zone.Owing to uplift and denudation in part of central uplift belt and fault-cut by tectonic inversion of Nantun Formation,Meteoric water eluviation alternated reservoir of bedrock buried hill and generate the reservoir accumulation zones.The positive inversion fault and active normal fault in the reverse period in the end of Yimin sedimentation adjusted the oil-gas that collected in the fault depression at early stage to Damoguai Formation,and accumulated in inversion structure,and formed the secondary oil and gas accumulation zone.