论油气运移的“高速公路”及源外找油思想

Expressway of Hydrocarbon Migration and the Thought to Find the Reservoirs beyond the Region of Source Rock

源控论认为,有效烃源岩的展布范围或者生油凹陷的展布范围控制了油气的平面分布,油气主要分布在距离主力生油洼陷20～30km的范围内。松辽盆地西部斜坡大部分地区超出有效烃源岩的展布范围,但在西坡发现了富拉尔基油田、平洋油气田、图牧吉油砂矿和套保油田等油区。笔者在松南西斜坡发现一条大型"人字"形沟谷体系,该沟谷体系对白城水系具有重要的控制作用,在河道上的探井都有良好的油气显示,套保和图牧吉油田(距离主力生油凹陷达120km)的成因也与沟谷体系有关。嫩一、二段湖相泥岩形成的区域性盖层,沟谷体系的高孔—高渗储层以及单倾斜坡使得长岭凹陷生成的油气具备了向西部斜坡长距离运移的地质条件。因此,盆缘发育的"人字"形沟谷体系及其控制的河道沉积是油气长距离运移的"高速公路",只要存在圈闭条件,沿着"高速公路"就可以实现"源外"找油。

According to source control theory, most reservoirs lie in ambient region of source rock. The kernel content of ＂Source Control Theory＂ is that oil ＆ gas migration distance is short. Most of them distribute between 20 km and 30 kin. The west slope in the Songliao basin is outside of source rock distribution. However, several oilfield have been＇ found in the west slope, such as Fulaerji, Pingyang ,Taobao, Tumuji and so on. A large channel is found in the west slope and this research shows that this channel control distribution of Baicheng ＆ Honggang river system. The channel and its river system is the most effective migration way for the reservoirs in the west slope. The wells in this channel all have good signs oil migration. The regional cap formed by the lacustrine shale in Nen Ⅰ and Ⅱ members, sandstone of high porosity and high permeability in the channel, and single slanted slope provide the geologic conditions for the hydrocarbon generated in Changelin Sag to migrate towards the west slope the channel and its river is a kind of expressway of hydrocarbon migration. Therefore, it is possible that explorer may seek reservoirs alone expressway beyond the region of source rock.