Well integrity is one of the highest operational risks for E&P companies across the industry. As such, well integrity concerns are high priority for operational excellence. Electromagnetic Corrosion Logs have been more frequently acquired as Cased-hole logging services enabling the quantification of multi-barrier well integrity. Due to ease of data acquisition through logging operations and the ability to model remaining metal thickness per-barrier from acquired surveys, demand for Electromagnetic Corrosion Logs has been sharply growing across the industry. Electromagnetic Corrosion Logs can compliment conventional integrity tests and can be used for well integrity compliance where business-critical decisions are accordingly made.
Electromagnetic corrosion logs are run more frequently across assets to investigate time-lapse per-barrier integrity status for multi-barrier systems (multiple concentric tubulars). Degradation in barrier integrity in operating wells present integrity risks. Harsh operating environments during production/injection, sour environments, life-time wear and tear, and shallow aquifers all affect wellbore integrity in the form of internal and external metal loss. Electromagnetic Corrosion Logs are currently reported to be capable of quantifying total remaining metal per-casing (separately) up to three barriers.
In 2016, a yard test was conducted in Oman to assess the limitations of different Electromagnetic corrosion tools. The test consisted of multi-barrier concentric oil-field tubulars of different sizing and set-up. Four tubular set-ups (simulating routine well completions) were constructed with man-made "corrosion" features to assess raw, processed and interpreted Electromagnetic Corrosion logs. The man-made features included defects of various shapes and configurations distributed axially and longitudinally as well as machined thickness-loss areas with precise thresholds. Multiple service providers with different tools and configurations were requested to acquire corrosion logs through the yard test "completions."
This paper investigates Electromagnetic Corrosion Log technology. It illustrates the physics, practice, and applied technology scope of Electromagnetic Corrosion Logs gathered from the yard test and multiple surveys in Petroleum Development of Oman (PDO). The outcome is improved awareness of operational windows, tool resolution and sensitivities, detection capability, data QC and analysis, processing, and modeled thickness outputs. Some discussion is made around the limitation of Electromagnetic Corrosion Logs and the uncertainty in thickness estimation, and recommendations for this technology's scope for application.