|Formation damage can originate from various mechanisms at several stages during the life cycle of a field. Evaluation of formation damage requires an integrated approach with laboratory, engineering and geological input.
- Critical velocity test or fines migration tests. These tests basically involve core flow tests at various rates to determine at which velocity certain (clay) minerals become dislodged and cause permeability impairment. Critical velocity test can also be carried out on core plugs to establish at what maximum rate a well test should be conducted without damaging the near wellbore region.
- Permeability reduction due to mud invasion can be investigated with return permeability. The effect of the mud on permeability/productivity is evaluated with core flow tests. These tests can be extended by using various clean-up fluids to determine with type of clean-up fluid enhances (scores) permeability again.
- Simple mercury injection tests yield pore throat size distributions of the formation and can be used as input for mud design.
- Mud or polymer gel liftoff pressures.
- Evaluation of mud cake removal treatments.
- Consultancy for mud design.
Of course formation damage prevention is better than a formation damage remedial solution. Proper mud design, mineralogical information and good engineering practice are just a few major parameters in formation damage prevention.