A Novel Eccentricity Correction Approach to Enhance Casing Damage Evaluation for Forty-Arm Caliper Logging in Horizontal Wells

Multi-arm caliper logging tools provide a high-precision technology for monitoring tubing and casing integrity. However, due to the wellbore structure of horizontal wells and the self-weight of the instrument, the multi-arm caliper logging data of horizontal wells typically exhibit obvious eccentricity, resulting in a high misjudgment probability in the quantitative evaluation of oil and casing pipe damage. In this manuscript, simulation experiments were conducted using the 5.5-inch casing under laboratory conditions. The experiments clarified the response characteristics of forty-arm caliper logging tools in centered and eccentric states within intact and damaged casing. An equivalent model combining the instrument and the horizontal pipe structure was established, and a new method for correcting instrument eccentricity based on the forty-arm caliper logging data in horizontal wells was developed through theoretical analysis. The proposed model effectively overcomes the limitations of existing correction methods under casing damage conditions, reducing the relative error by up to 0.53% and 1.16% in intact and damaged well sections, respectively, compared to the ellipse-fitting algorithm. This effectively improves the correction coincidence rate for eccentricity influence of multi-arm caliper logging tools under various conditions in horizontal well. Applying this established method to the processing and interpretation of forty-arm caliper logging data in horizontal wells provides robust technical support for the high-precision quantitative evaluation, damage location identification, and repair of horizontal well casing.