夹层垂向渗透率对低渗透油层含油饱和度的影响

Effect of vertical permeability of interbed on the oil saturation of the reservoir with low permeability

根据夹层具有垂向窜流条件时的数学模型 ,计算了 9种开采方式下高、低渗透层平均含油饱和度 ,以及低渗透层平均含水饱和度 .结果表明 :当夹层垂向渗透率大于 10 - 5μm2 时 ,不能起到隔层作用 ;夹层垂向渗透率为 5× 10 - 7～ 5× 10 - 6 μm2 ,按注水井仅高渗透层射开 ,生产井仅低渗透层射开 ,或在此基础上 ,高渗透层尖灭 1 3,低渗透层尖灭 1 3两种方式开采时 ,低渗透层平均含油饱和度变化较大 ,低渗透层储量被动用程度相对较高 ;当夹层垂向渗透率在 10 - 5～10 - 4μm2 ,按前种方式开采 ,高、低渗透层平均含油饱和度同时递增 ,说明高、低渗层出现“水驱舌进”或“水窜”现象 ,这是油田开采中必须预防的 .

According to the mathematical model developed for the condition of vertical cross flow through an interbed, the average oil saturations of reservoir with high and low permeability and water saturation of reservoir with low permeability by using nine development models are calculated. The result shows that the interbed can not become an isolate layer when the value of vertical permeability of interbed is more than 10 -5 μm 2. When the value is in the range of 5×10 -7 to 5×10 -6 μm 2, it leads to a large change of the oil saturation of reservoir with the low permeability by using two oil production models, namely the reservoir with high permeability put to use for water injection well, and the reservoir with low permeability is open for oil well; or one third of reservoirs pinch out. The first model could lead to increase of the average oil saturation of reserves with low and high permeability when the vertical permeability of the interbed is 10 -5 -10 - 4 μm 2. It shows that reservoirs with high and low permeability are in the danger of water breakthrough, and it must be prevented in oilfield development.