Suspended solids in the injection water cause impairment of water injectivity during waterflooding operations. Suspended solids affect reservoir properties and decrease the permeability of reservoir rocks causing an increase of injection pressure and a decrease in water injectivity. Removal of all suspended solids from injection water is an expensive and economically unfeasible process. To minimize the effects of suspended solids to the formation, it is necessary to determine an impairment mechanism of suspended solids on oil displacement and, therefore, optimize the water treatment process. In this paper, an analytical model that describes the relationship between injection water quality and impairment mechanisms on oil displacement is presented. A formation impairment was calculated, introducing the parameter called impairment ratio, which represents the ratio between suspended solids and pore size distribution of reservoir rock. Based on the impairment ratio, decreases in porosity and permeability were calculated with changes in capillary pressure, relative permeability, and displacement efficiency. The model was tested for three different types of injection water. Results indicated the presence of formation impairment even with the smallest particles. Suspended solids had the greatest influence on porosity and permeability impairment. The model could be used as input for reservoir modelling studies for monitoring and controlling displacement efficiency during waterflooding as well as for planning and modification of water treatment units.

中文翻译：

---

预测注水过程中悬浮固体对注水驱油效率影响的分析模型

注水过程中悬浮的固体会损害注水能力。悬浮的固体会影响储层特性并降低储层岩石的渗透率，从而导致注入压力增加和注水量下降。从注入水中去除所有悬浮固体是一种昂贵且在经济上不可行的过程。为了使悬浮固体对地层的影响最小化，有必要确定悬浮固体对驱油的损害机理，从而优化水处理工艺。本文提出了一个分析模型，该模型描述了注入水质量与减损机理对驱油率之间的关系。计算了地层减损，引入了称为减损率的参数，代表了悬浮固体和储集岩孔径分布之间的比率。根据减损率，计算出孔隙度和渗透率的降低，这取决于毛细管压力，相对渗透率和驱替效率的变化。测试了该模型的三种不同类型的注入水。结果表明即使最小的颗粒也存在形成障碍。悬浮的固体对孔隙率和渗透性损害的影响最大。该模型可以用作油藏建模研究的输入，以监测和控制注水期间的驱替效率，以及用于水处理单元的计划和修改。孔隙率和渗透率的降低是通过毛细管压力，相对渗透率和驱替效率的变化来计算的。测试了该模型的三种不同类型的注入水。结果表明即使最小的颗粒也存在形成障碍。悬浮的固体对孔隙率和渗透性损害的影响最大。该模型可以用作油藏建模研究的输入，以监测和控制注水期间的驱替效率，以及用于水处理单元的计划和修改。孔隙率和渗透率的降低是通过毛细管压力，相对渗透率和驱替效率的变化来计算的。测试了该模型的三种不同类型的注入水。结果表明即使最小的颗粒也存在形成障碍。悬浮的固体对孔隙率和渗透性损害的影响最大。该模型可以用作油藏建模研究的输入，以监测和控制注水期间的驱替效率，以及用于水处理单元的计划和修改。结果表明即使最小的颗粒也存在形成障碍。悬浮的固体对孔隙率和渗透性损害的影响最大。该模型可以用作油藏建模研究的输入，以监测和控制注水期间的驱替效率，以及用于水处理单元的计划和修改。结果表明即使最小的颗粒也存在形成障碍。悬浮的固体对孔隙率和渗透性损害的影响最大。该模型可以用作油藏建模研究的输入，以监测和控制注水期间的驱替效率，以及用于水处理单元的计划和修改。