注水井污染半径计算新方法研究

Research of A New Method for Calculating Pollution Radius in Injection Wells

摘要: 针对注水井固相悬浮物和原油堵塞的问题，提出了一种新的计算注水井污染半径的方法。首先通过理论公式的推导，建立污染半径和污染区渗透率以及整个地层受污染后平均渗透率的关系；然后提出运用比吸水指数计算某一时刻储层受污染后的渗透率，绘出污染半径与污染区渗透率保留率的关系曲线；再结合室内岩心驱替模拟注入水对近井带的堵塞规律，建立污染半径的预测模型，并绘出污染半径与污染区渗透率保留率的关系曲线，两条曲线的交点即为所求的污染半径。以渤海某区块F25井为例，采用该方法计算得到某一时刻注水井的污染半径。该方法解决了理论公式与现场实际相结合的问题，为酸化解堵方案设计提供了借鉴。

Abstract: In consideration of the problems of solid suspension and oil blockage in injection wells, a new method was proposed for calculating pollution radius in injection wells. Firstly, the relationship between the formation average permeability and pollution radius aster the pollution was established by deriving theoretical formula. Then it was proposed that the specific water absorption index was applied to estimate reservoir permeability at a certain moment after it was polluted for drawing the permeability relation curve of the pollution radius and pollution zone. Combined with the core displacement experiment for simulating injection water blocking rule of the near wellbore zone, a forecast model of pollution radius was established to draw the permeability retention curves of the pollution radius and pollution area, the intersection of two curves was the objective pollution radius. By taking Well-F25 of a certain block in Bohai Oilfield, the pollution radius is calculated by the method. It can be used to solve the problem of the combination of theoretical formula and field operation; it provides reference for scheme design for acidized plugging removal.