New LWD Technology Provides High-Resolution Images in Oil- and Water-Based Muds for Improved Decision Making in Real Time

摘要

A recently developed logging-while-drilling (LWD) ultrasonic imaging tool has been field tested and shown to provide high-resolution images that give an early indication of problems during drilling operations. These images are compared to other LWD imaging techniques in oil-based muds to demonstrate the advantages of the new technology. The new tool employs a system of three equally spaced ultrasonic transducers along the circumference of the tool at the same level. This arrangement provides the high data density needed for the images and enables precise location of the tool in the borehole for accurate borehole corrections to the data, thereby enhancing the overall image quality. The images are used with other real-time LWD and measurement-while-drilling (MWD) measurements such as equivalent circulating density (ECD), and formation pressure tests (FPT), to monitor wellbore stability and other issues that can lead to non-productive time (NPT) during drilling operations. The new tool has been field tested in a number of wells in different parts of the world. These tests demonstrated the capabilities of the images to identify wellbore stability issues such as breakouts and cavings. The images can also be used to identify geologic features such as fractures and faults that can impact the drilling operation as well as the eventual production of the well. Examples will also be shown that combine the interpretation of the images along with other MWD and LWD measurements to provide a superior technique for wellbore stability management in real time. The new LWD tool provides high-resolution borehole images in oil-based and water-based mud systems. Previously, high-resolution images from an LWD tool were only available in water-based mud systems using electrical imaging tools. This new technology provides a much clearer image of the borehole that has been available in the past. The techniques developed for using this information in real time reduce the frequency and magnitude of borehole-related NPT events.