Formation damage refers to impairment of the reservoir caused by invasion of wellbore fluids during drilling or completion. It can be mechanical, by plugging of pore spaces, or chemical, such as clay swelling or precipitation of salts. Formation damage reduces permeability near the wellbore and hydrocarbon flow. While reservoir properties cannot be controlled, operational changes can minimize damage during drilling, completion and production to enhance well productivity.

2.  Formation damage is defined an impairment
to the reservoir caused by the invasion of
wellbore fluids during any interval of well.
 In petroleum industry, it is said that
“Formation damage is an expensive headache
to the oil & gas industry”.

4.  Mechanical Damage
 Chemical Damage

5.  The formation damage that is caused by the
plugging of solids or grain particles with in
the pore space or throats of the formation
rock which ultimately results in the
impedance to the flow of fluid.

7.  Injection of low salinity water into a
sandstone reservoir could result in clay
swelling & fines migration.
 Injection of incompatible water(contains high
sulphate content) & the formation water contains
high concentration of calcium, strontium or
barium ions.
 As a result, sulphate salts of these cations will
precipitate in the formation & may cause severe
formation damage.

9.  Fluid-fluid incompatibility(emulsion
generation etc)
 Rock-fluid incompatibility(clay swelling etc)
 Fines invasion & migration(particles etc)
 Phase trapping & blocking(water entrapment
in gas reservoirs)
 Biological activity

10.  Invasion by drilling
 Partial Completion
 Plugging of perforations
 Bacterial growth
 Dispersion of clays (Swelling)
 Presence of mudcake
 Presence of high gas saturation around the
well bore

11.  Over the last five decades, a great deal of
attention has been paid to formation damage
issues for two primary reasons:
 Ability to recover fluids from the reservoir is
affected very strongly by the hydrocarbon
permeability in the near-wellbore region
 Although we do not have the ability to control
reservoir rock properties and fluid properties, we
have some degree of control over drilling,
completion, and production operations

12.  Thus, we can make operational changes,
minimize the extent of formation damage
induced in and around the wellbore, and
have a substantial impact on hydrocarbon
production. Being aware of the formation
damage implications of various drilling,
completion, and production operations
can help in substantially reducing
formation damage and enhancing the
ability of the well to produce fluids.