Maximizing Value in Offshore Brazil Well Interventions Applying Through-Tubing Cement Evaluation

Abstract

Abstract

Abstract This paper presents the application of a novel method for evaluating cement integrity in dual-string completions of deepwater wells, utilizing state-of-the-art logging tools within Brazilian well scenarios. Success cases are thoroughly discussed and analyzed, showcasing the technology's benefits, including reduced operational time, mitigated risks, and decreased CO2emissions. These outcomes align with industry regulations, emphasizing the method's potential to enhance log reliability, and its efficiency during a complex well integrity assessment process. The applied dual string cement evaluation consists of acoustic logging methodology. The first stage was focused on the development of theoretical acoustic modeling and simulation to characterize and identify signatures related to the different barrier conditions. The second stage comprised the planning and application of field tests to ratify and validate the TTCE logging application. After carrying out the field logging, data processing and data interpretation, some log results could be compared with subsequent conventional cementing evaluation logs performed after removing the production string. This paper describes the pioneer cementing evaluation logging behind dual string in Brazil, using an innovative methodology adapted for Brazilians scenarios. The challenges to apply this methodology include thick tubing and casing strings, fast formation, formation creeping (shale and salt), barite sag, among others. The proposed TTCE method and its log data were validated through field tests, which included logging runs before and after removing the completion string. The logs were compared and the differences identified between the logging methods were evaluated. In addition to the cement percentage, the technique could determine the interfaces between cement, barite sag and the drilling fluid above the top of solid (TOS). All these data created value for the intervention, and this methodology will benefit from more field logging (increasing the data base) by getting better trained models (machine learning) to increase its robustness. Keeping the production string in the well reduces intervention time, costs, environmental footprint and risks in workover and plug and abandonment operations. However, a comprehensive evaluation of the performance of through tubing logging technology needs to be considered to ensure the robustness of the permanent barrier. This novel acoustic methodology for cement evaluation in concentric tubulars provides valuable information, yet its limitations shall be discussed by the interpreters.