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Abstract Continued technological advances have made logging-while-drilling (LWD) technologies a reliable and widely used class of tools to evaluate and describe the reservoir. High-resolution imaging-while-drilling, in particular, offers a detailed view of fractures, vugs, faults, bedding planes, and other borehole features in deviated and horizontal wells. One benefit of imaging-while-drilling is the ability to evaluate the formation in real time. This can provide better well placement in the target formation. However, unlike many conventional logging tools that can be used in a wide range of conductive and non-conductive mud environments, resistivity imaging tools require special considerations to obtain high-quality data. Drilling fluid resistivity is one of the important considerations to be verified when a micro-imaging log is planned. In the Arabian Gulf, the most common muds used for drilling horizontal wells are non-damaging fluid (NDF) systems that use calcium chloride to weight the mud. This brine mud is highly conductive, which can cause the emitted current of a micro-imager to flow into the mud instead of the formation, which results in poor image data quality. If a highly conductive mud is combined with a moderate- to high-resistive formation, the image quality can further deteriorate. While a mud system with lower conductivity (such as barite-based mud) is preferred when imaging high resistivity formations, the use of such a mud system may not be possible. Several ADCO wells with various mud and formation conditions were drilled with a new micro-imaging tool. This tool features a unique button design that creates multiple image resolutions and depths of investigation, which improves the chances of obtaining a high-quality image in various drilling conditions. While the resulting images from these wells varied, the tool enabled the development of a logging and integrated geoscience solution to overcome the mud and formation challenges and provide better reservoir characterization. This extended abstract reviews the micro-imager's deployment, the considerations that need to be reviewed before a micro-imaging job commences, and the integrated solution that was developed for imaging highly resistive formations. |
