What is formation impairment and what are some of its causes?
Disposal well impairment is simply the loss of injectivity, resulting in an increase in injection pressure at constant volume or a decrease in injection volume at constant pressure. Formation impairment should be distinguished from formation damage. Impairment is a symptom while damage is a cause. Impairment may be reversible while damage inherently is not. Injectivity that has been impaired may be restored with appropriate remedial action such as washout, acidizing or other chemical treatment. Formation damage will require more drastic action such as fracturing, perforating or re-completion. Impairment is the result of the accumulation of contaminants somewhere along the flow path of the injected fluid. This may occur within the well tubing, on the formation face or within the fractures or pores of the injection zone rock. Contamination may come from scale, corrosion byproducts, oil, suspended solids, paraffin, emulsion, incompatible treating chemicals, microbiologicals or other sourc
