What does a fracture look like on an acoustic image log?

• A. Sinus curve
• B. Elliptical curve
• C. Straight line
• D. Zigzag line

Answer: (D)

Acoustic image logs map reflections from the borehole wall, and fractures show up where there’s a sharp, planar discontinuity. The line that marks a fracture on the image isn’t a smooth curve because the tool views the wall in a rotating, circular way and records many ray paths as depth changes. When a fracture reflects energy, the trace appears as a sequence of angular, abrupt segments rather than a smooth, continuous curve, giving a zigzag pattern. This jagged appearance reflects the imaging geometry, rock roughness, and variations in fracture orientation along the borehole. A straight, smooth line or a curved sinusoidal or elliptical shape would not typically represent a single fracture on an acoustic image log.