断裂在乌尔逊凹陷油气成藏中的作用

乌尔逊凹陷断裂发育较多,断裂呈条带状分布且具多期活动的特点。研究发现,乌尔逊凹陷深部发育的大断裂是深源无机CO₂向上运移的主要通道控制着CO₂气藏的形成与分布;断裂活动时期与源岩大量排烃期的匹配关系控制着乌尔逊凹陷源岩的油气聚集量,凹陷断裂第二次活动时期与南屯组源岩大量排烃期匹配关系较好,有大量南屯组源岩生成排出的油气沿晚期与长期继承性断裂运聚成藏;平面上延伸较远的大断裂在乌尔逊凹陷中对油气侧向运移.起到了通道作用;良好的断层垂向封闭性控制乌尔逊凹陷油气的聚集与分布:较好的断层侧向封闭性是乌尔逊凹陷断块、断鼻和断层遮挡三种圈闭类型形成的重要条件。

Effect of Faults on Hydrocarbon Accumulation in Wuerxun Sag

There exist many faults featuring by striped distribution and multiphase activity in Wuerxun sag. This study showed that the deep major faults acted as main passages of deep inorganic CO2 migrating upward, which controlled the formation and distribution of CO2 gas reservoirs; the matched relationship between the faulting activity period and the mass expulsion period of hydrocarbon from source rocks controlled the volume of petroleum accumulation into source rocks in Wuerxun sag. There are a great deal of oil and gas expulsed from Nantun source rocks followed by migration and accumulation along late and long-term inherited faults, because of good matched relationship between the second faulting activity period and expulsion period of hydrocarbon in the sag; the major faults extending longer in plane effected as main passages on oil and gas lateral migration in the sag; the good vertical sealing faults controlled the accumulation and distribution in the sag; and good lateral sealing faults dominated the formation of faulted block trap, faulted nose trap and fault-screened trap in Wuerxun sag.