Advanced Analytical Tools in Microbially Influenced Corrosion (MIC) Failure Diagnosis
An offshore oil and gas operator in the North Sea was experiencing decreased well injectivity in a newly commissioned produced water reinjection facility. Over a period of six years, this worsened to a point of minimal to no injection capacity.
Despite the managed continuous application of a scale and corrosion inhibitor and batch biocide additions, these flow assurance challenges severely impacted project feasibility. SGS subject matter experts identified the potential tubing and casing integrity threat and provided a summary of all potential impacting factors.
The operator’s primary theory was that reservoir fines or clays accumulating in the system might be impacting water injectivity and well integrity. The operator commissioned SGS to provide onsite sampling and off-site laboratory testing and consultancy support to diagnose the root cause of the observed operational impacts.
Produced water well injectivity decline was prevalent, resulting in:
- Reduced capacity for produced water disposal
- Project feasibility impacts/production deferral
- Significant compliance concerns related to well integrity and safety
- CAPEX demand for new well tubing/replacement
- Increased OPEX spend on a suite of chemicals unable to remediate the flow assurance challenge
SGS provided on-site specialist sampling support as the well tubing was recovered. A series of corrosion anomalies penetrating the tubing wall were identified in multiple sections of tubing sections recovered. For each section, a swab was taken from within a representative corrosion site and preserved for onshore analysis. A series of tubing samples were retained, preserved in resin mounts and progressed for SGS QEMSCAN analyses.
SGS MiRAS Next Generation Sequencing (NGS) was conducted on all swabs, showcasing the extensive microbial diversity present and the high portion of MIC driven consortia present in the corrosion zones. SGS QEMSCAN surface imagery of cross cuts identified the presence of typical biofilm morphology and pit propagation. No clays or sand were present, however layers of inorganic deposits, aligned with typical microbial influenced corrosion by-products, were present. A firm diagnosis was presented for MIC related tubing failure impacts and appropriate mitigation guidance was presented. Well tubing replacements were induced. To date no further tubing integrity or injectivity decline impacts have been reported.
SGS MiRAS services and consultancy support provided effective investigation, sampling, analyzing and root cause assignment.