Design and Simulations of a High-Temperature and High-Pressure Acoustic Logging Piezoelectric Transducer

In ultra-deep wells above 8000 m where the bottom hole temperature exceeds 230°C, it is difficult for existing logging instruments to satisfy the requirements of high temperature and high pressure resistance. In this paper, a novel design of high-temperature and high-pressure resistant logging acoustic transducer is proposed, in which the laminated piezoelectric transducer is solid-filled instead of conventionally liquid-filled. Through the finite element multi-physical simulations of the logging acoustic transducer, the vibration modes, stress distribution and sound field distribution are analyzed to optimize the transducer structure parameters. When a 200 MPa ultrahigh pressure is applied around the logging acoustic transducer, the results show that the maximum stress on its piezoelectric plate can be reduced to less than 5 MPa after structural optimization. In addition, the sound field distribution and directivity of the logging acoustic transducer are also analyzed and performed well, which provides technical guidance for physical manufacturing.