Multi-Measurement Logging-While-Drilling Imager: New Enabler for Wide-Scale Comprehensive Geosciences Applications in Oil-Base Mud

摘要

Borehole images have been widely used in industry for almost three decades for different geological and petrophysical applications; though these logs were often limited in application in the wells drilled with oil-base mud (OBM) due to resolution and coverage constraints against the downhole environment. Recent advances in technology helped address this issue with wireline logging; however, the logging-while-drilling (LWD) capabilities for high resolution borehole images in OBM remained limited thereby limiting any real-time applications of this data. The new innovative multi-measurement LWD imager provides game-changing enabler for wide-scale comprehensive solutions from drilling-efficiency till field development. Singular image acquisition for subtle features at high resolution could often miss out on a lot of important events, thereby constraining the optimal characterization of sub-surface and downhole conditions. To properly understand, characterize and demystify the sub-surface, Industry's first multi-measurement imager was developed with high resolution capabilities in OBM; with ultrasonic and electromagnetic measurements physics. Ultrasonic and Electromagnetic measurements are made at multiple frequencies by multiple sensors to ensure that the features on borehole wall are observed and resolved, both. The complementing nature of these technologies provide far better application capabilities, with multiple full-bore images being acquired simultaneously for apparent resistivity, amplitude and transit time by multiple sensors to overcome downhole operational challenges and variability of formation response without introducing complexity to the drilling bottom-hole assembly (BHA). The apparent resistivity images from electromagnetic measurements provide rich information of the sedimentological, diagenetic and structural features while the ultrasonic images are more sensitive to the near wellbore fracture, drilling induced features and borehole conditions. Availability of the multiple measurements in real-time and relevant time lends the borehole image data for various applications, enabling drilling optimization, smoother and efficient operations and detailed geological characterization. Such comprehensive applications were not available earlier for wells drilled with OBM or any non-conductive mud.