Abstract

Recent developments have advanced ultrasonic technology to the point where images can be viewed which are similar in clarity to electrical imaging tools, bringing new applications to all wellbores. Ultrasonic high resolution images, previously known as borehole televiewers, have provided a breakthrough in borehole imaging, especially in oil-based muds. The Ultrasonic Borehole Imager (UBI^#) tool measures both amplitude and transit time with peak-envelope processing techniques which provide an enhanced accuracy.

Applications of the tool can be divided into two classifications, geologic and borehole deformation. Geologic applications consist of computation and analysis of structural and stratigraphic dips and thin bed analysis. Analysis of these images on a workstation allows the interactive computation of dipping features and a detailed depositional environment interpretation for reservoir delineation. High resolution thin bed analysis and cumulative sand count analysis in oil-base muds are possible by using an amplitude cut-off on a continuously computed median amplitude curve. These analyses are verified with integration and comparison of core data.

Stress analysis and borehole deformation measurements are calculated from radius data. These measurements are accurate to better than .02" in diameter and less than 2° in azimuth orientation, allowing the calculation of minimum stress directions and various displays of borehole shapes. These displays make it possible to view and identify the various borehole deformation features such as key seat, borehole breakout, slippage, sloughing, and coal ledging.