摘要
油 (气 )在岩层中必须达到某一门限值 (临界饱和度 )才开始运移的观点并不正确。在输导层中 ,油气运移(二次运移 )的主要条件是运移动力必须大于毛细管阻力和摩擦阻力。油气运移的动力由水动力和浮力提供 ,均与连续油 (气 )相长度有关 ,只要连续油 (气 )相长度足够长 ,油气就能发生运移。因此 ,输导层中的油 (气 )运移与含油 (气 )饱和度并不存在必然关系。盖层和烃源岩层基本上是无渗透性的 ,油 (气 )要发生渗漏和运移 ,必须要在连续油相两端形成 10MPa以上的压差 ,在岩层内部仅靠剩余压力是无法达到的 ,所以只有突发事件才能使烃源岩中的油 (气 )发生运移 (初次运移 ) ,与油 (气 )饱和度没有关系。在动力压差一定、孔隙结构和润湿性不变的储层中 ,水驱油最后可达到一个较稳定的残余油饱和度 ,但改变水驱条件 (动力、孔隙等 ) ,则残余油饱和度亦必然发生变化。所以 ,油 (气 )是否能够运移 ,取决于连续油 (气 )相的长度 ,而不由含油 (气 )
The viewpoint that oil and gas in rocks can migrate only when they reach certain threshold is not correct.The primary condition for oil and gas migration (secondary migration)is that the dynamic force must be greater than capillary resistance and fractional resistance.The dynamic force includes hydrodynamic force and buoyancy,both of which are related to the length of oil and gas phases.That is to say,oil and gas can migrate so long as the length of oil or gas phase is sufficient.This suggests that there is no inevitable relationship betwee oil and gas migration and saturation.It is pointed out that differental pressure greater than 10 MPa between the two ends of the oil or gas phase is needed to cause the migration.Only sudden event can produce such differential pressure but not formation residual pressure.When dynamic differential pressure is certain,the reservoir's pore texture and wettability remain invariable,water driving oil may reach stable residual oil saturation.But the residual saturation would change with the variation of water driving condition.So it is considered that oil and gas can migrate or not is determined by the lengh of continuous oil(gas) phase but not the oil saturation.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2000年第3期197-200,213,共5页
Oil & Gas Geology
关键词
毛细管力
连续油相
油气运移
含油气饱和度
oil(gas) saturation
capillary force
continuous oil phase
oil gas migration
