Traditional solution for oil and gas production equipment is the use of carbon steel (CS) due to its reduced cost, compared to more noble and corrosion resistant materials. To ensure the integrity of these equipment, the use of carbon steel needs to be accompanied by corrosion mitigation measures, like the use of Corrosion Inhibitors (CI). In the present context with more and more constraining environmental requirements and with the increase of water cut, the use of corrosion inhibitors become challenging. An optimized use of these chemicals is necessary to limit as much as possible, their impact on the environment, but also to limit the costs associated to their use, while the anticorrosion efficiency is kept sufficient to protect the carbon steel (CS) equipment.
The Company strategy is to use CI that are selected via laboratory testing programs. The corrosion inhibitors are evaluated through a series of tests aiming to be representative of the future use conditions. Parameters like carbon dioxide (CO2) content in the associated gas, temperature and produced water salinity, flow velocity and flow regime, presence of sand are considered when the anti-corrosion efficiency is evaluated. Nevertheless, the field conditions cannot be fully reproduced in the laboratory and some aspects like foaming and emulsion tendencies, are not fully assessed during testing. This can be assessed only during a field test, where the CI is exposed to the real conditions.
The paper presents the experience of the use of 5 corrosion inhibitors in our assets in Guinea Gulf. Monitoring results in term of performance of injection and anti-corrosion efficiency are presented. Issues experienced, such as production instabilities, oil/water separation, unreliability of monitoring techniques are also presented. These feedbacks are intended to be used further on to adapt the testing methodology used during the selection of the CI in the laboratory.