Effect of Drag Reducing Agents (DRA) in Water Injection Well

Applying drag reducing agent (DRA) into water injection system has
improved injection capacity of wells by reducing the friction that occurs inside the
well tubing. Many studies were conducted to understand the behaviour and optimise the performance of DRA when applied in multiphase flow. However, less study is
being done to evaluate the effect of DRA on the formation, especially in the near wellbore zone. It is expected that DRA in injected water will cause permeability reduction, albeit the factor and exact percentage of reduction are subject to the current study. A water injection system using core flood equipment was used in this work. Polyacrylamide (PAM) and polysaccharide (Xanthan Gum) were mechanically degraded under high shear rates before injected into the core to
simulate field condition. Injection rates were varied so that the relationship between
permeability reduction and the rates could be established. It is found that low injection rate of 1cc/min gives more permeability reduction compared to high injection rates at 5cc/min, while Xanthan gum DRA solution gives more permeability reduction compared to polysaccharide DRA solution. Backflow was
performed to restore core permeability, but the permeability restored was less than
initial permeability. CT scan was run to study the permeability reduction of the core. However, no significant difference was observed. It is suggested that the injection rates need to be considered when designing the water injection wells with DRA
additives.