苏北盆地金湖凹陷油气二次运移动力分析

金湖凹陷是苏北盆地第二大产油凹陷，但各区带油气富集程度分布不均。分析表明，油气二次运移对油气富集程度有较大影响。基于油气二次运移的驱动力为水动力和浮力两类认识，通过对凹陷油田水性质、地下古水流形式和地层流体压力系统特征分析，排除了水动力是油气二次运移的主动力；依据油水界面张力、孔喉半径和润湿角等参数，计算了阜宁组输导层在关键时刻的毛细管阻力并与浮力相比较，得出二级构造带油气侧向二次运移的驱动临界条件，发现油相连续长度远小于含油带宽度，且临界油相长度小的地区油气较富集（反之，则较贫）。因此认为油相静浮力为本区油气二次运移的主动力，并由此指出凹陷油气二次运移方向与有利聚集部位。

Dynamical analysis of secondary migration of oil and gas in Jinhu sag, Subei basin

Jinhu sag is the second largest oil-producing sag in Subei basin. Its hydrocarbon enrichment varies largely in different zones. By analysis it shows that secondary migration of oil and gas have great effect on hydrocarbon enrichment degree. Hydrodynamic force and buoyancy are assumed the driving force in the paper. From the properties of oil-field water, underground paleocurrent type and analysis of fluid pressure system, it can conclude that the hydrodynamic force of the Jinhu sag is not the main action force to the secondary migration of hydrocarbon. Capillary resistance of conducting layers of Funing Formation in key time can be calculated from oil-water interfacial tension, radius of pore throat and wetting angle; et al. Compared it with buoyancy, it can derive out the critical driving condition of lateral secondary migration in second- order structure zone. It can also find out that continuous length of oil phase is far shorter than the width of petroleum zone. Shorter the critical oil length of zone, richer oil and gas it has. So, oil static buoyancy is the active force of secondary migration in the area. From this, the orientation of secondary migration and favorable accumulation part of hydrocarbon can be determined.