Azimuthal acoustic logging can survey the downhole formation more accurately, and the acoustic source is the crucial component of the downhole acoustic logging tool with azimuthal resolution ...characteristics. To realize downhole azimuthal detection, assembling multiple transmitting piezoelectric vibrators in the circumferential direction is necessary, and the performance of azimuthal-transmitting piezoelectric vibrators needs attention. However, effective heating test and matching methods are not yet developed for downhole multi-azimuth transmitting transducers. Therefore, this paper proposes an experimental method to comprehensively evaluate downhole azimuthal transmitters; furthermore, we analyze the azimuthal-transmitting piezoelectric vibrator parameters. This paper presents a heating test apparatus and studies the admittance and driving responses of the vibrator at different temperatures. The transmitting piezoelectric vibrators showing a good consistency in the heating test were selected, and an underwater acoustic experiment was performed. The main lobe angle of the radiation beam, horizontal directivity, and radiation energy of the azimuthal vibrators and azimuthal subarray are measured. The peak-to-peak amplitude radiated from the azimuthal vibrator and the static capacitance increase with an increase in temperature. The resonant frequency first increases and then decreases slightly with an increase in temperature. After cooling to room temperature, the parameters of the vibrator are consistent with those before heating. Hence, this experimental study can provide a foundation for the design and matching selection of azimuthal-transmitting piezoelectric vibrators.
In this paper, AISI 304L austenitic stainless steel has been subjected to plasma nitriding at 673 and 681 K lasted for 6, 18, 24, and 36 h. The morphology, microhardness, phase, and microstructure ...evolution of the nitrided layer were studied. Not only an expanded austenitic phase (γN) but also Cr-nitrides were formed in the nitrided layer. Transmission Electron Microscopy (TEM) study showed the formation of amorphous and nanocrystalline phases in the surface layers of the samples. The erosion-wear and intergranular corrosion (IGC) resistance behaviors of the nitrided samples were studied in detail. As compared to the non-nitrided sample, the erosion-wear resistance of the nitrided layer at normal impact angle doubles after nitriding at 673 K for 6 h, as a result of the formation of γN phase. Degree of sensitization (DOS) of IGC is gradually enhanced with the increase of nitriding time as indicated by a double loop electrochemical potentiokinetic reactivation (DL-EPR) measurement. This is assigned to the nanostructuring and to the Cr-depletion in the areas adjacent to the Cr-nitrides.
•Amorphous and nanocrystalline phases were detected on the top of the nitrided layer by TEM.•The DOS of IGC was analyzed in detail by DL-EPR measurement.•Erosion-wear resistance of the sample nitrided at 673 K for 6 h was doubly enhanced.•The enhancement of the surface microhardness (673 K-36 h) reached up to ∼ 6 times.
Acoustic logging instruments generate high voltages in the order of thousands of volts. Electrical interferences are thus induced by high-voltage pulses that affect the logging tool and make it ...inoperable owing to damaged components in severe cases. High-voltage pulses from the acoustoelectric logging detector interfere with the electrode measurement loop through capacitive coupling, which has seriously affected the acoustoelectric signal measurements. In this paper, we simulate high voltage pulses, capacitive coupling and electrode measurement loops based on qualitative analysis of the causes of electrical interference. Based on the structure of the acoustoelectric logging detector and the logging environment, an electrical interference simulation and prediction model was developed to quantify the characteristics of the electrical interference signal.
To increase the accuracy of reservoir evaluation, a new type of seismoelectric logging instrument was designed. The designed tool comprises the invented sonde-structured array complex. The tool ...includes several modules, including a signal excitation module, data acquisition module, phased array transmitting module, impedance matching module and a main system control circuit, which are interconnected through high-speed tool bus to form a distributed architecture. UC/OS-II was used for the real-time system control. After constructing the experimental measurement system prototype of the seismoelectric logging detector, its performance was verified in the laboratory. The obtained results showed that the consistency between the multi-channel received waveform amplitude and benchmark spectrum was more than 97%. The binary phased linear array transmitting module of the instrument can realize 0° to 20° deflection and directional radiation. In the end, a field test was conducted to verify the tool's performance in downhole conditions. The results of this test proved the effectiveness of the developed seismoelectric logging tool.
Ultrasonic imaging logging can visually identify the location, shape, dip angle and orientation of fractures and holes. The method has not been effectively applied in the field; one of the prime ...reasons is that the results of physical simulation experiments are insufficient. The physical simulation of fracture and hole response in the laboratory can provide a reference for the identification and evaluation of the underground geological structure. In this work, ultrasonic scanning experiments are conducted on a grooved sandstone plate and a simulated borehole and the influence of different fractures and holes on ultrasonic pulse echo is studied. Experimental results show that the combination of ultrasonic echo amplitude imaging and arrival time imaging can be used to identify the fracture location, width, depth and orientation, along with accurately calculating the fracture dip angle. The evaluated fracture parameters are similar to those in the physical simulation model. The identification accuracy of the ultrasonic measurement is related to the diameter of the radiation beam of the ultrasonic transducer. A single fracture with width larger than or equal to the radiation beam diameter of the ultrasonic transducer and multiple fractures with spacing longer than or equal to the radiation beam diameter can be effectively identified.
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.
To improve the performance of acoustic logging tool in detecting three-dimensional formation, larger and more complicated transducer arrays have been used, which will greatly increase the difficulty ...of fault diagnosis during tool assembly and maintenance. As a result, traditional passive diagnostic methods become inefficient, and very skilled assemblers and maintainers are required. In this study, fault-diagnosis requirement for the acoustic logging tool at different levels has been analyzed from the perspective of the tool designer. An intelligent fault-diagnosis system consisting of a master-slave hardware architecture and a systemic diagnosis strategy was developed. The hardware system is based on the embedded technology, while the diagnosis strategy is built upon fault-tree analysis and data-driven methods. Diagnostic practice shows that this intelligent system can achieve four levels of fault diagnosis for the acoustic logging tool: System, subsystem, circuit board, and component. This study provided a more rigorous and professional fault diagnosis during tool assembly and maintenance. It is expected that this proposed method would be of great help in achieving cost reduction and improving work efficiency.
This work investigates the effect of microstructure on tensile properties and corrosion behavior of a Zr–Sn–Nb–Fe–Cu–O alloy. Scanning electron microscope, transmission electron microscope, electron ...back scattering diffraction, tensile tests and autoclave corrosion test were jointly carried out to characterize in detail the microstructural features and properties of the alloy studied. The corrosion rate constant increases with decreasing the degree of recrystallization. The sample with slower evolution of undulated interface exhibits higher tensile strength and possesses better corrosion resistance. The plasticity of sample can hardly be the rigorous limitation on corrosion performance, which is attributed to the consistent consummation of the deformed substrate around the interface during corrosion to make the inner undeformed substrate become fresh interface. Furthermore, second phase particles (SPPs) may play a role in the nucleation of cracks in the oxide.
The Zr–0.5Sn–0.3Fe–0.35Nb–0.05Cu–0.08O alloy samples with different microstructures are obtained by three kinds of processing procedure. The correlation among microstructures, tensile properties and corrosion behavior have been investigated in detail. A schematic illustration which is used to describe the corrosion mechanism is particularly elucidated in the manuscript concerns the deformation and consumption of local metal substrate. Display omitted
•The corrosion rate constant increases as decreasing the degree of recrystallization.•The sample with higher tensile strength possesses better corrosion resistance.•The plasticity of sample can hardly be a rigorous limitation on corrosion resistance.•Second phase particles might play a role in the nucleation of cracks in the oxide.
The increasing needs for new types of computing lie in the requirements in harsh environments. In this study, the successful development of a non‐electrical neural network is presented that functions ...based on mechanical computing. By overcoming the challenges of low mechanical signal transmission efficiency and intricate layout design methodologies, a mechanical neural network based on bistable kirigami‐based mechanical metamaterials have designed. In preliminary tests, the system exhibits high reliability in recognizing handwritten digits and proves operable in low‐temperature environments. This work paves the way for a new, alternative computing system with broad applications in areas where electricity is not accessible. By integrating with the traditional electronic computers, the present system lays the foundation for a more diversified form of computing.
A non‐electrical mechanical metamaterial to achieve a neural network empowering handwritten number recognition without an electricity supply is presented. By overcoming the challenges of mechanical signal transmission efficiency and intricate layout design, a mechanical neural network based on kirigami metamaterial is achieved. This work provides an effective method for various science and engineering applications where electricity is not accessible.
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