呼和湖凹陷断裂特征及其对油气成藏的影响

断裂的形成演化过程对油气的运聚成藏具有重要的影响。本文系统分析了呼和湖凹陷断裂特征、断裂演化及其与油气成藏的关系。研究表明,呼和湖凹陷以T_(22)和T_(04)反射层为界,划分为3套构造层,分别为下部伸展断陷构造层、中部断坳构造层,上部坳陷构造层,其中上部构造层中断裂不发育。纵向上主要发育了两套断裂系统,下部断裂系统展布方向主要是北东东向、北东向和北北东向。上部断裂系统展布方向主要为北北东向和北北西向。发育4种类型的断裂,分别为早期伸展断裂,中期走滑断裂,早期伸展中期走滑断裂和早期伸展中期走滑晚期反转断裂。断裂的主要形成时期为南屯组末期、伊敏组末期和青元岗组末期。断裂的形成和演化影响烃源岩的分布和热演化程度,形成多种类型的圈闭,为油气垂向运移提供良好的运移通道。其中在主力生油洼槽及其周边的几个控陷断层附近有利于油气富集。

Characteristics of fault and its impacts on hydrocarbon accumulation in Huhehu depression

The formation and evolution of fault played important roles on the accumulated reservoir of hydrocarbonThe characteristics，evolution of fault and the relation between reservoir of Huhehu depression were analyzed in this articleThe results show that，with the T22 reflection horizon for boundary，Huhehu depression could be divided into three main structural layers，the lower extensional fault depression layer，the middle faulting sinking layer and the upper dawn warping layer，in which fault aplasia in the upper dawn warping layerThere have been two faulted systems which were developed in the longitudinal direction，the spreading direction of the lower faulted system mainly with NEE，NE and NNE direction and the upper faulted system mainly with NNE and NNW directionThere are four types of faults in this area，including early extensional faults，middle strike slip faults，early extensional and middle strike slip faults，early extensional and middle strike slip and later reverse faultThe main formation periods of faults are in the late depositional periods of Nantun，Yimin and Qingyuangang FormationsThe formation and evolution of fault influenced the distribution and thermal evolution of source rock，formed multi type traps and provided a good migration channel for the vertical migration of hydrocarbonSo the main petroleum generating sub sag and the areas among controlling depression fault nearby the main petroleum generating sub sag are beneficial to hydrocarbon enrichment.