幕式成藏理论的提出及其勘探意义

THEORY OF EPISODIC MIGRATION AND ACCUMULATION: EVIDENCE AND EXPLORATION SIGNIFICANCE

幕式成藏是一种快速、高效的成藏方式,并常常具有周期性,因而对于高富集度大中型油气田的形成具有十分重要的意义。同渐进式成藏一样,幕式成藏也是含油气盆地一种普遍存在的成藏方式,特别是对于多构造运动、断裂发育的盆地以及异常压力比较发育的盆地(如前陆盆地和裂谷盆地等),幕式成藏往往占有重要地位;而在构造运动相对较稳定的克拉通盆地,一般以渐进式成藏为主。与渐进式成藏不同,幕式成藏在时间上并不完全受生烃窗控制,而主要受控于区域构造运动、断裂活动和异常压力的演化,因此盆地的构造演化史、断裂活动史和异常压力发育史往往决定了幕式成藏史。幕式成藏理论的提出,不仅是对传统油气成藏理论的一个重要补充,更重要的是拓宽了油气勘探领域,进一步明确了大中型油气田的勘探方向。

It is evidenced that episodic migration and accumulation is rapid, efficient and periodic as a kind of reservoir formation, and therefore significant to the formation of mid-large oil and gas fields. Like gradual migration and accumulation of hydrocarbon, episodic migration and accumulation is also found to be quite common type of reservoir formation in petroleum basins. Compared with gradual migration and ac cumulation, episodic migration and accumulation is particularly important in basins that experienced strong orogenies, fault activity or have abnormal pressures. Unlike gradual migration and accumulation, which is more important in cratonic basins, episodic migration and accumulation is more important in foreland and rift basins. It should be noted that episodic migration and accumulation is not fully controlled by hydrocar bon generation window in time, but mainly by tectonic events （fault activity in particular） and evolution of abnormal pressure as well. Consequently, history of tectonic changes, fault activity and/or abnormal pressure development determine that of episodic migration and accumulation. The theory of episodic migration and accumulation is not only an important supplement to the traditional theory of petroleum geology, but also broads the exploration domain and further defines the exploration orientation of mid-large oil and gas fields .