Through-Tubing Casing Deformation Inspection Based on Data-Driven Koopman Modeling and Ensemble Kalman Filter

Maintaining well integrity in the oil and gas industry is crucial for operational safety, environmental protection, and cost-effective production. A key aspect of pipe integrity is casing deformation, which is caused by formation swelling, subsidence, tectonic activity, salt creep, corrosion, and thermal stresses. Other factors include completion defects and operational conditions. Evaluating casing deformation is essential, but existing logging technologies require tubing removal to inspect the casing, a costly and time-consuming process. Through-tubing casing inspection is highly desirable to reduce these interventions and make monitoring more routine. However, conventional electromagnetic through-tubing casing inspection faces two major challenges. First, the tubing shielding effect limits magnetic flux penetration, with only 20% reaching the casing, leading to weak responses for reliable analysis. Second, the tubing position inside the casing varies, often being eccentric, introducing uncertainties in logging data processing. This paper presents a novel approach using data-driven modeling and the ensemble Kalman filter (EnKF) to address these issues. By recognizing the system’s dynamic nature and tubing shielding effects, an enhanced dynamic mode decomposition (DMD) based on Koopman operators was developed. This method treats measurement as a dynamic system, accounting for casing deformation changes. The EnKF incorporates an observation model trained on finite element simulation data, considering different wellbore scenarios, logging conditions, and parameters such as casing/tubing diameters, weights, and tool position. Additionally, the method integrates physical constraints to improve accuracy. This innovative approach effectively mitigates the tubing shielding effect, improving through-tubing casing inspection accuracy. It quantitatively estimates tubing eccentricity, enabling the removal of nonlinear effects, even in extreme eccentricity cases where the tubing contacts the casing. The tool’s performance has been validated in both laboratory and field conditions across various casing/tubing combinations. Simulated assessments achieved a 5% deformation ratio accuracy for casing diameters up to 13.375 in. This technology has broad applications in energy sectors, including through-tubing well integrity monitoring for production, injection, gas storage, and geothermal wells. It also aids in stuck pipe diagnostics without pipe manipulation, pipe eccentricity assessment for plug and abandonment (P&A) operations, and tubing clamp orientation detection for control line positioning analysis. Through-tubing casing deformation measurements can be integrated with conventional multibarrier inspection tools, such as multifinger calipers and electromagnetic thickness tools, to provide a comprehensive pipe integrity evaluation solution.