二连盆地赛汉塔拉凹陷边界断裂构造特征及其控藏作用

Structural characteristics of the boundary fault and its control on hydrocarbon accumulation in Saihantala Sag,Erlian Basin

为了研究赛汉塔拉凹陷的形成、演化及油气成藏规律,利用地震、钻井、测井等资料对边界断层锡林断裂构造特征进行了分析,并探讨了边界断裂构造对油气成藏的控制作用。结果表明,锡林断裂具有明显的分段性,不同段其断面形态存在差异,表现为中段断面相对陡倾,南、北段则相对平缓。由平均断裂活动速率可知,阿尔善组和腾格尔组沉积期是锡林断裂的强烈活动期。锡林断裂的形成与演化对油气成藏具有控制作用,具体表现为:①断裂活动控制生烃洼槽及优质烃源岩的形成,并促进烃源岩的热演化;②断裂活动控制砂体展布,并形成多种类型的圈闭;③断裂、砂体和不整合面共同构成了油气运移的输导格架。因此,生烃洼槽周边受锡林断裂控制而形成的圈闭是油气聚集的有利场所。

Xilin fault is the boundary fault of Saihantala Sag, which controls origin, evolution and hydrocarbon accumulation of Saihantala Sag. Based on seismic and well data, the structural characteristics of Xilin fault were analyzed, and its control on hydrocarbon accumulation was discussed. The results show that the Xilin fault is a listric fault in profile and it consists of three segments. The southern and northem segments are low dip, while the central segment is steepened. The mean active rate indicates that Xilin fault had a strong activity during the sedi- mentary period of A＇ ershan Formation and Tengge＇ er Formation. The evolution of Xilin fault controls the reser- voir accumulation, which can be proven by： （ 1 ） Xilin fault played an important role on the formation of hydrocarbon generating depression and the accumulation of high-quality source rocks, and it also promoted the maturi- ty of source rocks; （ 2 ） the evolution of Xilin fault has a great influence on palaeogeomorphology and the distri- bution of sand bodies, which dominated the formation of varied traps; （3） faults, sand bodies and unconformity surfaces constituted the hydrocarbon drainage system together. Therefore, the traps controlled by Xilin fault around the source depression are favorable for hydrocarbon accumulation.