The bulk of Nigeria’s oil and gas production come from the Niger Delta area of the country. The environment is generally susceptible to high salinity, which influences quick set in of external corrosion on metallic products.

The surface casing of wells located mostly in the swamps of the Niger Delta are prone to external corrosion attack at the splash zone around the wellhead region. The effect of this corrosion ultimately results in loss of load bearing capacity of the wellhead when the severity is very high. At rig based well reentry, collapse of the surface casing had occurred under the weight of the Blow Out Preventer (BOP) during its installation. Repair of such failure at the wellhead is mostly unplanned and can be expensive.

The external corrosion at the wellhead region is influenced by the oxygenation of rainwater retained in the annular space between the conductor pipe and the surface casing. Similarly, the cement micro annulus that emanates behind the surface casing tend to retain some relatively small amount of water which invariably do cause an invisible, slow but steady development of corrosion on the surface casing.

The proposed paper will proffer solutions to incidence of external corrosion on the surface casing with a view to enhancing production life, safety and reducing operating cost.

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