Advanced Techniques for Wellbore Stability Evaluation Using Logging-While-Drilling Technologies

Abstract

Abstract Logging-while-drilling (LWD) technologies have long been used for real-time formation evaluation and Geosteering. Several optimization techniques for drilling and completions have been developed, based on data acquired from LWD technologies. In this paper, methods and techniques are presented where LWD measurements were utilized for the purpose of safely planning, drilling, and completing vertical and horizontal boreholes. In addition to resistivity tools known to provide shallow and deep readings, density tools provide azimuthal borehole images from two detectors of different source-detector spacings, allowing their data to have different depths of investigation (DOI). Comparison between the responses of sensors having different DOI over multiple logging passes can be used to assess wellbore deterioration over time. Ultrasonic LWD imagers also provide high-resolution, azimuthal hole-size measurements allowing advanced evaluation of wellbore conditions. Integrating multiple sensors of different DOI in the logging suite, and comparing their individual responses, gives more insight into the borehole conditions than analysis of single-sensor data alone. Data from LWD was integrated with surface-data-logging (SDL) data to provide full analysis of wellbore conditions in real time. Time-lapse analysis using data acquired while tripping out of the hole revealed deterioration that was not observed in the first logging passes while drilling. Interventions were made to mitigate wellbore instability and lessons have been captured to prevent hole deterioration in subsequent wells drilled in the area. Workflows have been developed to LWD technologies for wellbore stability monitoring to mitigate borehole deterioration, thereby optimizing operations for drilling and completions.