Oil and gas facilities can be subjected to faster deterioration during period of shutdown than those in operation; hence replacement of damaged equipment or piping can be very costly. Among the myriads of short-term preservation methods available, chemical treatment preservation program represents one of the most effective method to minimize the risk of continuous deterioration, hence safeguard the overall integrity of the facility.
This paper details the unique challenges encountered within the Al-Wafra oilfield when implementing chemical treatment method under the stagnant and highly corrosive conditions, as a result of unscheduled shutdown. These conditions alongside the entrapped sludge and accumulation of fluids at low spots is expected to lead to the dominance of under-deposit (UDC) and microbial induced corrosion (MIC), hence any chemical program should be designed to effectively mitigate these damage mechanisms. Consequently, the methodology developed involved initially flushing the facilities with less saline water to remove deposits and sediments, and subsequently treating the entire facility with a mixture of corrosion inhibitor, oxygen scavenger and biocide in brackish water. This is expected to significantly reduce the corrosion rates in comparison to uninhibited system. A range of corrosion monitoring techniques alongside fluid chemistry analysis was implemented for the field monitoring to ascertain the overall efficacy of the program as per key performance indicators (KPI).
Key words: chemical treatment, risk, stagnant condition, mechanical cleaning, corrosion inhibitor, oxygen scavenger, biocide, corrosion monitoring, under deposit corrosion, sulfate reducing bacteria.