依据水驱前缘移动规律优化分层注采压差

Optimization for Injection-Production Pressure Difference Based on the Movement Law of Water Flooding Front in Two Layers

针对两层层间注采压差的优化问题,依据水驱油藏基本渗流理论,运用数学解析法,推导出了径向渗流两层层间注采压差优化模型。将模型应用于鄂尔多斯盆地某砂岩油藏数据模拟,计算出的见水时间相对误差为6.28%~7.48%。研究表明,上下两层水驱前缘位移跟井筒半径的平方差之比与其相应的注采压差之比成直线函数关系,水驱前缘的移动速率与水驱前缘位移成反比函数关系。定义了两层储渗纵向非均质系数,系数越大,储渗纵向非均质程度越严重。有效解决层间矛盾的最佳分层注采压差,须满足的条件是两层储渗参数之比值与相应注采压差之比值的乘积等于1。只有在这种条件下,上下两层在不同位移处的渗流速率才会相等,才不会发生层间突进现象。

In order to optimize the injection-production pressure difference of two layers,based on the water flooding theory of oil reservoir,the formula for describing the interlayer pressure difference about radial flow state is deduced by using mathematical analytic method.The interlayer breakthrough time in a block of the Ordos basin is calculated by the method.The result is close to the real time,with a relative error of only 6.28%~7.48%.It is indicated that the ratio about the quadratic difference of displacements of water-flooding frontal edge and wellbore radius in two layers is in a linear functional relationship with the ratio about the corresponding injection-production pressure differences.And the movement velocity of water flooding front is in an inverse proportional functional relationship with the water flooding front.The heterogeneity coefficient of two layers is defined.The larger the coefficient is,the more serious the interlayer heterogeneity.The effective way to solve interlayer breakthrough is to adjust the injection-production pressure difference in different layers.The best stratified differential pressure is the one that the product of the ratio of the flow field parameters and ratio of corresponding injection-production differential pressure is equal to 1 in the two layers.Only under this condition can the interlayer breakthough not occur.And the seepage velocities of the upper and lower layers are equal at different displacements in the condition.