Abstract
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
