叠合盆地断裂上、下盘油气差异聚集效应及成因机理

断裂沟通叠合盆地不同层位、不同时代的烃源岩和生储盖组合,成为连接烃源岩和各种圈闭的重要渠道,导致形成了多种类型与断裂有关的油气藏。断裂上、下盘油气聚集差异现象十分普遍。通过剖析松辽盆地、柴达木盆地典型断裂带油气藏成藏条件,认为其根本原因是由于断裂上、下盘具有不同的地质特征和油气运聚成藏条件,它们往往具有互为消长的关系。油气富集在断裂的上盘还是聚集在断裂的下盘,主要取决于:断裂的作用,断距与储、盖层的厚度关系,断裂倾角,区域盖层之下断裂断开烃源岩或油气层的层数,断裂形成或活动时期与主力烃源岩排烃高峰时期的关系等 8个主要因素。

ACCUMULATING DIVERSITY AND ITS MECHANISM BETWEEN HANGING AND LOWER WALLS OF FAULT IN SUPERIMPOSED BASIN

A fault should be an important channel between source rocks and traps, since it linked up both the varied layers, and source rocks with different ages and source reservoir cap association in a superimposed petroliferous basin, which resulted in creation of multy type petroleum accumulations related to faulting. The phenomenon of divergent accumulating between hanging and lower walls of fault was very common, because there were different geologic features, petroleum migrating and accumulating conditions in the hanging wall and the lower plate. By analyzing the Songliao and Qaidam basins, it was discovered that petroleum accumulating in the upper or in the lower plates depending on the following factors: fault controlling roles, relationship between fault displacement and thickness of reservoir and cap rocks, fault dipping angle, the numbers of source rocks or petroleum reservoirs cut by fault under the regional cap rocks, relationship between faulting age and datings of hydrocarbon generating and squeezing.