Innovative Workflow for Wellbore Stability Evaluation Using Logging-While-Drilling Technologies

Abstract

AbstractLogging-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 emerging and existing 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.Optimizing drilling and completions can be achieved by continuously monitoring for signs of deteriorating borehole conditions in data coming from different LWD sensors like density, resistivity, or ultrasonic imagers. 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. Emerging tools like ultrasonic LWD imagers provide high-resolution, azimuthal hole-size measurements allowing advanced evaluation of wellbore conditions.Analysis of LWD data showed the potential to identify, mitigate or eliminate existing and potential wellbore stability risks. 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.Customized workflows were established where available 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 utilize existing and emerging LWD technologies for wellbore stability monitoring. Procedures have been established to mitigate borehole deterioration, thereby optimizing operations for drilling and completions.