D. Torres, R. Strickland and M. Gianzero
Halliburton Logging Services
Abstract
Circumferential borehole imaging tools detect, as sine waves, planar features intersecting the borehole at an angle. The amplitude and phase of these sine waves (combined with high resolution caliper measurements) determine the relative dip and strike of the corresponding features. A new approach has been developed which recognizes these sine waves automatically, calculates their amplitude and phase, and then determines their associated dip and strike angles.
Traditionally, these calculations have been performed either manually or by correlation methods commonly used for dipmeter logs. The proposed method relies upon a pattern recognition scheme which mimics human observations. It not only identifies and measures the sinusoidal images but it also places a confidence level on each identified feature, which aids in interpretation. The procedure first generates a binary image highlighting only relevant features. This image contains features possibly hidden in the original image and yet eliminates any insignificant vertical details. The data are then processed for sine waves with their appropriate dip and strike angles.
Examples of this method, applied to borehole images made by the Circumferential Acoustic Scanning Tool (CAST), are presented and compared to results obtained with dipmeter tools.