Development and Testing of a Portable Acoustic Logging System on Cuttings

In order to measure the real-time acoustic velocity in the formation while drilling, a portable acoustic logging system on cuttings with high precision was developed based on the research of acoustic logging on cuttings. In the design of this logging system, integrated circuit of pulse generator and oscilloscope was adopted. In addition, software functioning as oscilloscope that could quickly read and store waveform data was studied for this system. By using the ultrasonic transmission method, an ultrasonic probe was used to emit ultrasonic waves with 1 MHz frequency to measure the P-wave velocity and S-wave velocity of the acoustic wave passing through cuttings samples. Results comparisons were conducted on both the laboratory test and the dipole acoustic logging in actual drilling. The results showed that the accuracy of acoustic velocity measurement was more than 98.0%, and the consistency of acoustic logging data of cuttings and wireline acoustic data was greater than 80.0%. This system could not only be used to monitor abnormal formation pressure while drilling, but also to evaluate rock brittleness, compressibility, drillability and wellbore stability in real time.