Non-Integral Wells are common in every aged field and managing their integrity is becoming a challenging issue, particularly in large fields and for complex dual completions such as the case in ZADCO operated fields. As part of the Well Integrity Management System (WIMS), integrity concerns are identified, investigated and subsequently mitigation measures are recommended to restore the well integrity, all in a systematic approach. Well barrier integrity is given the highest priority; therefore a comprehensive Risk Register and Risk Ranking process is implemented by ZADCO Well Integrity Team. The Risk Register process utilizes every related data and integrity investigation results to evaluate the integrity of the well primary & secondary barriers for every flow path. An individual integrity assessment is performed on the different containment sections in a well such as wellhead, inner and outer annuli and zonal isolation. Based on the severity, consequences and likelihood of a barrier failure the individual containment is given a risk rank according to ADNOC/ZADCO risk matrix. The overall risk ranking of a well reflects the highest risk rank of any of its containments. To complete the risk register, existing safeguards are addressed and appropriate short and long term mitigation actions are recommended to keep the risk at ALARP.

Oil producers completed with carbon steel were threatened with sweet corrosion due to early water breakthrough and the presence of carbon dioxide in the associated produced gas. In severe cases corrosion led to problems which interrupted production and put the wells in an unsafe service condition. Remediation or replacement of damaged tubing was not cost effective or not feasible. A robust corrosion inhibition program through periodic squeeze treatment was implemented. Optimized and improved through the years it provided effective protection of the downhole completion and extended well operating lifetime.