高低浓度聚合物交替注入油藏试井解释方法

Well testing interpretation method of alternating injection into reservoir by high and low concentration polymer

聚合物交替注入驱油技术作为进一步提高驱油效果的重要手段被应用于海上油田中,但目前对于聚合物驱油藏试井模型的研究较少考虑注入方式的影响,导致许多海上聚驱油藏实际数据拟合效果不理想。通过考虑海上高低浓度聚合物交替注入的实际情况,运动数学物理方法、渗流力学理论,基于严格的数学推导,建立了高低浓度交替注入3区复合油藏试井解释模型,绘制了井底压力响应特征曲线,并对其影响因素进行讨论。分析表明:典型曲线可划分为7个流动段,高低聚合物浓度差异导致第4段压力导数曲线下降,聚合物初始浓度主要影响Ⅰ区、Ⅱ区径向流阶段压力导数曲线高低和过渡段凹子的大小,Ⅰ区复合半径主要影响高浓度聚驱波及范围,Ⅱ区复合半径主要影响低浓度聚驱驱替前缘位置。实例应用证明了本文模型的正确性与实用性。

Alternating polymer flooding technology,as an important means of further improving the effect of polymer flooding,is applied in offshore oilfield.However,the influence of injection mode is seldom considered in the practice of well testing model of polymer flooding reservoir,which leads to the unsatisfactory effect of actual data fitting.By considering the actual situation of alternating injection of high and low concentration polymer,a well testing model for alternating injection into three-zone composite reservoir by high and low concentration is established based on the theory of fluid flow in porous media and on the mathematical physical method.Accordingly,response character curves of well pressure are plotted and its influencing factors are discussed by the numerical inversion method.The result shows that the typical curves have seven stages and the remarkable feature in the typical curves is the obvious upturn in the transient stage between low concentration and high concentration polymer solution.The initial concentration of polymer mainly affects the pressure derivative curve in the first and second radial flow stages and the size of the concavity in the transition section.The compound radius in first zone mainly affects the range of polymer flooding with high concentration and the composite radius in the second zone mainly affects the flooding front of polymer flooding with low concentration.Practical application proves the validity and practicability of the model,and provides the basis for the adjustment of polymer flooding fields.