ABSTRACT
Intensive corrosion and bacteria problems were encountered by a mature onshore field with over 30 years production history, which has resulted in frequent work overs for tubing / casing repair and replacement. This has necessitated the investigation into root causes, the review of the existing risk evaluation and chemical treatment activities, in view to protect future production and the integrity of new drilled wells.
Based on the analysis of field historical production, work over, sampling, chemical treatment and monitoring data, the predominant corrosion mechanism and a suitable corrosion risk model is validated and qualified for this field. The model has proved to be successful in identifying the corrosive wells with good agreement with the historical data.
Not only the probability of corrosion but also the consequence of failure are considered and captured in the new risk model; using this newly developed work flow, a full field mapping of the corrosion risks is carried out which allows the field to planning chemical budget ahead and to make sure the wells at highest risks are well protected. Improvements in chemical injection are discussed in this paper.
