With the development of underground space

more and more attention has been paid to the special areas on borehole wall. In order to overcome the low resolution of traditional ultrasonic borehole imaging technology

a new borehole imaging method based on ultrasonic synthetic aperture technology is proposed to improve the resolution and image quality. Firstly

high resolution synthetic aperture focusing technique(SAFT) is used to synthetically process a large number of cross-section scanning echo signals

so as to enhance the reflection signal and suppress the interference signal

which makes the echo of the corresponding typical area at the rock wall more prominent. Then the sound amplitude and sound time parameters of the scanned cross-section echo signals are extracted. The principle of ultrasonic drilling image reconstruction based on correlation is proposed based on the synthesized characteristics of sound amplitude and sound velocity parameters. After superimposing the detection data of different depths

the borehole reconstruction image with more obvious focus area is formed. Finally

the method is applied in practical engineering

and its feasibility and accuracy has been verified.