Oil production is decrease when flow restrictions occur in wellbore induced by chemical and/or mechanical changes.

The major contribution of these issues can be outlined as follows.

• Flow assurance problems such as paraffin or asphaltenes
• Formation damage e.g. Solids plugging,Clay-particle swelling or dispersion,Saturation changes,  Wettability reversal
• Mechanical failures due to sand production, collapse, scaling and corrosion