Research on acoustic logging while drilling transmitting technologies

Abstract

Acoustic logging while drilling (LWD) technology plays an important role in oil and gas exploration and development. Compared to traditional wireline logging, LWD must address more additional crucial problems, such as great noise confusions. This paper studies a series of technologies to improve the transmitting performances of LWD tools. First, we verified that the shear wave remote detection technology successfully adopted in wireline logging was also suitable for LWD, which could significantly expand its detection range. In addition, we calculated its dominant excitation frequency bands, which were different with wireline logging. Second, a class AB push-pull excitation circuit was designed. The results demonstrated that this circuit could obtain ideal excitation signals for LWD transmitting transducers. Furthermore, the signal shapes, excitation frequencies and cycle amounts are easily to adjust. In this study, we proposed a broadband impedance matching technology to solve the impedance mismatching problem between the excitation circuits and the excitation transducer. Acoustic experiments showed that this technology improved emitting powers of LWD transducers significantly.