High Resolution LWD Oil Based Mud Imaging via Impulse Radar – Hydrocarbon Case Studies

High resolution borehole images are key in characterising complex reservoirs and mitigating risk. For decades, borehole images have been primarily acquired via wireline, but as reservoirs become more inaccessible and borehole trajectories more complex, the appeal of Logging While Drilling (LWD) imaging measurements has grown. LWD imaging measurements have been available for over a decade, primarily using ultrasonic and electrical measurement techniques. Ultrasonic methods are affected by the annulus size and mud properties and thus don’t always work well in heavy muds and/or in large stand-offs (such as 12 ¼” or larger holes). Oil Based Mud (OBM) systems can also be challenging for resistivity-based microimaging tools. The resolution of OBM LWD images is generally lower than Water Based MUD (WBM) tools, which can lead to missing critical structural features in complex reservoirs. An LWD oil-based mud imaging tool has been introduced, which uses an impulse radar source/microwave antenna system to create high resolution micro-electrical images. It is much less affected by standoff and mud weight and can operate effectively in holes up to 22 inches in diameter. The images are of high vertical and azimuthal resolution, with 1 cm features readily distinguishable. The tool simultaneously acquires both wellbore shape and microelectrical images, make it a powerful tool for characterising both well integrity and formation properties. Since the introduction of the tool in 2020, more than 25,000 metres of data have been acquired in a variety of geologies from Europe, North America, and Australia. This paper focuses on hydrocarbon examples in OBM, illustrating how the measurements can be used to understand laminated reservoirs. Images clearly illustrate the complexities of the reservoir at a level of detail difficult to characterise with the traditional logs. High resolution radar-based LWD OBM images are a powerful tool for understanding the geology and structure of complex reservoirs and can acquire data in difficult environments where wireline logs may not be available. This paper presents a set of field cases demonstrating how the novel impulse radar LWD imaging tool performs across a range of borehole environments and geological complexities. The tool provides highresolution images in oil-based mud and large-diameter wells, revealing detailed features such as thin laminations, fractures, and subtle changes in borehole shape. Through comparisons with ultrasonic and wireline imaging, we highlight the complementary strengths of each method and show how the radar tool can fill critical gaps in formation evaluation and well integrity analysis.