Microbial Induced Corrosion Of Subsea Pipeline in the Gulf Of Suez

In mid May, 1996, a leak was developed in a 24" crude oil line which transfers the untreated crude oil from El-Morgan field at Gulf Of Suez to the onshore process facilities. The line was installed in April, 1993 from carbon steel, API-SL XS - 60, tubing with wall thickness 0.75 inch. A diving survey was carried out after oil spill using side scan sonar survey and an Remote Operating Vehicle (R.O.V) video inspection identified the leak to be due to internal corrosion in 8 joints located at depth 240 - 250 feet. After fixing the leaks, complete ultrasonic survey was performed using high resolution intelligent pig. The ultrasonic data with the sample analysis of the deposits accumulated a head of the pig confirmed the mode of corrosion as internal Microbial Influenced Corrosion (MIC) in 6 o'clock position. A comprehensive review of the corroded line history and the available corrosion monitoring data and the applied corrosion mitigation program refereed to the following:

1. Corrosion monitoring using weight loss coupons, electrochemical devices, and / or chemical methods installed in the two ends of the subsea pipelines does not shows any sign of high corrosion rate (average 3 MPY).

2. Absence of frequent pigging process in the pipeline resulted in accumulation of sludge that caused under deposits corrosion.

3. Thermophilic SRB bacteria was not detected, however some non SRB's were detected.

This paper reviews in details the pipeline history, corrosion mechanism, inspection outlines, reservoir souring modeling and presents action plan to prevent this leak to happen again in future, with a brief introductory for mitigation options strategies and economics