Definition of Formation Damage
Unintended impedance to the flow of fluids into, or out of, a wellbore.
It relates to either a reduction in either rock conductivity or fluid mobility through the pore space
Damage mechanisms:
Reduction in absolute permeability
Reduction in relative permeability
Increase in fluid viscosity
Examples
Solids plugging
Clay swelling
Saturation changes
Wettability reversal
Emulsion blockage
Aqueous filtrate blockage
Precipitation of soluble salts
Fines migration
Deposition of paraffins or asphaltenes
Condensate banking
Others
Quantifying Formation Damage
Darcy’s Experiments
Henry Phillibert Gaspard Darcy (1803 ~ 1858)
Hydraulic engineer
1828, Designed 12.7 km long waterway in Dijon, France
1856, Suggested Darcy’s Law in his book
One of the Legendary scholars in Hydraulic/Petroleum Eng. area
Measured flow rate from vertical pipe full of sand.
Flow rate of fluid is proportional to;
Area
Difference in hydraulic head (pressure)
Length of pipe
It explains the flow of fluid in porous media.
Pressure Drop Calculation
Radial flow condition
Constant Flow Rate
Darcy’s Law
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