The study on permeability reduction during steam injection in unconsolidated porous media

The effluents from steam generators usually have low salinity and high pH level during steam injection. Steam and its condensate can cause particle migration and hydrothermal reactions. Those largely decrease production potential of heavy oil resulting from permeability reduction. The flow experiments were conducted in sand-pack filled with unconsolidated sands. This paper presented the experimental results to evaluate the influence of pH level and temperature on permeability reduction. Meanwhile, a series of hydrothermal reactions were conducted to analyze solubility of solid particles in steam condensate. The experimental results showed that steam condensate irreversibly reduced the permeability up to 43.52%, but the permeability was only restored to 66.32%. Sandstone interaction with high pH condensate leads to a serious dissolution of formation minerals and subsequent precipitation of new minerals. Particle migration and hydrothermal reaction constitute the primary damage mechanisms when steam and condensate of low salinity and high temperature are injected into unconsolidated porous media.