Corrosion of downhole tubulars can be a serious concern when the produced crude has a
high water cut (greater than15 to 20%) and a CO2 content of a few percent. Two options are
available for corrosion control: (a) use of a suitable corrosion inhibitor inside the tubing, or (b)
use of a suitable corrosion resistant alloy (CRA) for the tubing. Compared to CRAs, the use of
inhibitors has often been found to be more cost-effective for existing production wells with
corrosive characteristics.
An increased incidence of corrosion induced failures of downhole tubulars during the last
few years, prompted Kuwait Oil Company1 (KOC), to undertake field trials for downhole
corrosion inhibitor treatment in selected production wells . The efficacy of the inhibitor was
assessed by using a special electronic device known as the Downhole Corrosion
Measurement System (DCMS), as well as downhole corrosion coupons. Baseline corrosion
rates and fluid chemistry data were first collected from the well prior to inhibitor treatment over
a 5-6 week period. Corrosion Inhibitor treatment was then carried out using a batch technique
known as ‘tubing displacement’ and testing was carried out for another 5-6 weeks. A reduction
in uniform corrosion rates, and a drastic reduction in localized corrosion were observed after
inhibitor treatment compared to that obtained in the absence of the inhibitor.
Key words: Corrosion Inhibitor; Downhole Corrosion Monitoring; Downhole Corrosion
Measurement System