Acoustic Emission and Echo Signal Compensation Techniques Applied to an Ultrasonic Logging-While-Drilling Caliper

Abstract

A logging-while-drilling (LWD) caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM). The detection range is a major performance index of a UDM system. This index is determined by the blind zone length and remote reflecting interface detection capability of the system. To reduce the blind zone length and detect near the reflecting interface, a full bridge acoustic emission technique based on bootstrap gate driver (BGD) and metal-oxide-semiconductor field effect transistor (MOSFET) is designed by analyzing the working principle and impedance characteristics of a given piezoelectric transducer. To detect the remote reflecting interface and reduce the dynamic range of the received echo signals, the relationships between the echo amplitude and propagation distance of ultrasonic waves are determined. A signal compensation technique based on time-varying amplification theory, which can automatically change the gain according to the echo arrival time is designed. Lastly, the aforementioned techniques and corresponding circuits are experimentally verified. Results show that the blind zone length in the UDM system of the LWD caliper is significantly reduced and the capability to detect the remote reflecting interface is considerably improved.

A Novel Transfer Function Based Ring-Down Suppression System for PMUTs

“…Then the distance can be obtained through the difference between the arrival time of the echo signal and the emission time of the pulse signal (Time of flight, TOF). When the excitation signal is removed, the PMUTs continue to vibrate due to mechanical inertia called the ring-down vibration or “tailing” [ 4 ], as shown in Figure 1 b. During the ring-down stage, the echo signal will be affected by the ring-down vibration of the PMUTs, such as overlapped or distortion, which fails to distinguish the echo signal and TOF [ 4 , 5 ].…”

“…When the excitation signal is removed, the PMUTs continue to vibrate due to mechanical inertia called the ring-down vibration or “tailing” [ 4 ], as shown in Figure 1 b. During the ring-down stage, the echo signal will be affected by the ring-down vibration of the PMUTs, such as overlapped or distortion, which fails to distinguish the echo signal and TOF [ 4 , 5 ]. In pulse-echo mode, the first echo signal that can be received must arrive later than the end of pulse signal transmission.…”

“…At present, many efforts have been made to reduce the ring-down time or blind area of ultrasonic transducers, such as full-bridge acoustic emission [ 4 ], parallel resistors [ 12 , 13 ], Golay complementary pairs [ 14 ], amplitude detection [ 15 ], etc. The above methods are usually verified using bulk piezoelectric transducers, not PMUTs with much smaller bandwidth and higher Q .…”

“…The above methods are usually verified using bulk piezoelectric transducers, not PMUTs with much smaller bandwidth and higher Q . Yao et al [ 4 ] proposed a full bridge acoustic emission technique based on bootstrap gate driver (BGD) and metal-oxide-semiconductor field-effect transistor (MOSFET). When the excitation signal is removed, the full-bridge acoustic emission technique quickly consumes the residual energy.…”

Transformerless Ultrasonic Ranging System with the Feature of Intrinsic Safety for Explosive Environment

“…Due to the narrow working space in the industrial field, many special function vehicles have hidden hazards in the process of reversing, posing a huge threat to safety production [1]. In order to solve these kinds of problems, the ultrasonic detection technology is thus widely used for monitoring and early warning of safety distances because of its simple structure and fast response [2,3,4,5,6], and could be gradually seen in the potentially explosive atmospheres of gases and vapors.…”