A method of logging a perforation tunnel and associated features of the perforation tunnel can include the following features. A logging device including an ultrasonic transducer is located downhole into a well. The well has a casing. The ultrasonic transducer has a focal point that is a distance from the ultrasonic transducer so as to be behind the inner face of the casing. An ultrasonic signal is projected from the ultrasonic transducer. A reflection of the ultrasonic signal is reflected from an internal portion of the perforation tunnel, the perforation tunnel extending through the casing and into formation. A transit time is measured between transmission and reception of the ultrasonic signal. A position of the ultrasonic transducer corresponding to the ultrasonic transmission and reception of the reflected signal is determined.