Innovative Approach to Enhance Evaluation of Well Integrity in Unconventional Completions With FBE Coating

Cement bond evaluation across unconventional pipes, such as fusion-bonded epoxy (FBE) coated casings, presents many challenges for the existing conventional ultrasonic technology. The coating interface behaves as an additional interface affecting the acoustic impedance measurements from conventional ultrasonic tools. This work details the testing and validation of the flexural and ultrasonic tool to address these challenges. The new flexural and ultrasonic transducers that emit and receive the ultrasonic waves to probe the casing, cement, and cement-to-formation/second casing interface were used at surface in a pressurized safety tank. Four FBE coated pipe samples were tested; the samples varied in outside diameter and the slurry density with which they were cemented. To validate the flexural and ultrasonic tool response in FBE coated casing, the 7- and 9.625-in. FBE coated casings were set up in the tank to simulate measurements for each casing size. The simulation included two scenarios. First, the free pipe measurement involved filling the tank with fresh water (1.48 MRayls), targeting the 7-in. casing and then the 9.625-in. casing, with free pipe outside in the annulus. Second, the cemented pipe scenario involved applying a cement sheath to both casing targets, using 121 pcf (pounds per cubic foot) slurry for the 7-in. casing and 91 pcf slurry for the 9.625-in. casing, while maintaining fresh water (1.48 MRayls) inside the tank. Successful testing of the 7- and 9.625-in. pipe samples was performed with the flexural and ultrasonic tool. By simultaneously acquiring ultrasonic pulse-echo measurements and flexural wave imaging, the flexural and ultrasonic tool provides a high-resolution map of pipe thickness and cement with full azimuthal coverage in coated pipes. The results showed that the casing thickness and casing internal radius were as expected for the tested samples. The acoustic impedance of the annulus material obtained from flexural measurements was within the accuracy range of ±0.5 MRayl for both the 7- and 9.625-in. pipe samples in free pipe as well as cemented pipe conditions. Post-validation, the flexural and ultrasonic tool has been successfully deployed in more than 50 wells with coated casing and has helped in delivering enhanced cement and corrosion evaluation for all these wells. This work demonstrates the integration of advanced technology and technical expertise to enable reliable barrier evaluation for well integrity assurance.