Acoustic Emission Characteristics of Sedimentary Rocks Under High-Velocity Waterjet Impingement
- 295 Downloads
The success of waterjet drilling technology requires further insight into the rock failure mechanisms under waterjet impingement. By combining acoustic emission (AE) sensing and underwater sound recording techniques, an online system for monitoring submerged waterjet drilling has been developed. For four types of sedimentary rocks, their AE characteristics and correlations to the drilling performance have been obtained through time–frequency spectrum analysis. The area under the power spectrum density curve has been used as the indicator of AE energy. The results show that AE signals from the fluid dynamics and the rock failure are in different ranges of signal frequency. The main frequencies of the rock failure are within the higher range of 100–200 kHz, while the frequencies of the fluid dynamics are below 50 kHz. Further, there is a linear relationship between the AE energy and the drilling depth irrespective of rock type. The slope of the linear relationship is proportional to the rock strength and debris size. Furthermore, the AE-specific energy is a good indicator of the critical depth drilled by the waterjet. In conclusion, the AE characteristics on the power density and dominant frequency are capable of identifying the waterjet drilling performance on the rock materials and are correlated with the rock properties, i.e., rock strength and cutting size.
KeywordsWaterjet Acoustic emission Rock fragmentation Time–frequency analysis
We would like to thank the KMT Company for sponsoring the Advanced Waterjet Cutting System for educational and academic use in university. We would also like to gratefully acknowledge the comments by the anonymous reviewers, which have helped to improve the manuscript. This work was financially supported by the National Natural Science Foundation of China (No. 51490652) and Science Foundation of China University of Petroleum, Beijing (No. 2462014YJRC048).
- Agus M, Bortolussi A, Ciccu R, Kim W, and Manca P. (1993) The influence of rock properties on waterjet performance. In: Paper presented at the Proceedings of the 7th American water jet conference, Seattle, Washington, USAGoogle Scholar
- Li G, Huang Z, Tian S, and Shen Z (2009) Research and application of water jet technology in well completion and stimulation in China. In: Paper presented at the 9th Pacific Rim International Conference on Water Jetting Technology, Fukushima JapanGoogle Scholar
- Mohan R, Momber A, and Kovacevic R (1994) On-line monitoring of depth of AWJ penetration using acoustic emission technique (pp. 649–664): Mechanical Engineering Publications Ltd., London, EnglandGoogle Scholar