Abstract
Wellbore stability analysis utilising wireline borehole images is well established. Today high resolution while drilling (LWD) images are available and they offer information in real time as well as the opportunity to acquire time-lapse information through re-logging while tripping. This paper discusses the usefulness of applying LWD image logs versus wireline image logs for determining wellbore stress through actual well examples. We discuss some benefits to early data acquisition as well as benefits due to technology.
We observe that the comparison of post-drilling images with detailed wellbore images acquired at time of drilling indicates that different features can be observed. These differences relate to the dynamic drilling environment and changes in the wellbore surface with time. In one example, both break-out and tension induced fractures are observed together, indicating an instability not predicted by traditional pore pressure models or seen in post-drilling wireline logs.
Today's drilling practices are continually pushing well design boundaries, for example in the areas of extended reach drilling, high pressure and geometrically complex well design. These scenarios require increasingly sophisticated wellbore stability management. With the real-time information within while-drilling high resolution images, a method is proposed for real-time incorporation in to well bore stability management that will reduce risks in these challenging well conditions.
