During the exploration and development of oil and gas fields, near-borehole formations exhibit considerable axial heterogeneity in elastic-wave velocity. However, existing borehole azimuthal acoustic imaging methods often ignore the effect of this heterogeneity on imaging performance and thus cannot accurately locate anomalous near-borehole bodies in formations with axially non-uniform wave velocities. Hence, a borehole azimuthal acoustic imaging method based on ray tracing and spatial scanning was developed to resolve this problem. Subsequently, the borehole azimuthal acoustic imaging responses of near-borehole caves in formations with axially uniform and axially non-uniform wave velocities were numerically simulated. Single-shot spatial-scanning imaging and multi-shot stack imaging were then implemented separately for PP (incident P-waves scattered as P-waves) scattered-echo data obtained from forward modelling. The results revealed that in formations with axially uniform velocities, the waveforms of scattered echoes from the near-borehole caves exhibited a typical parabolic variation as a function of depth. Conversely, in formations with axially non-uniform velocities, the waveforms exhibited an asymmetric, curved variation pattern with respect to depth. The conventional downhole three-dimensional spatial-scanning method could not accurately locate the near-borehole anomalies in formations with axially non-uniform wave velocities, producing large imaging errors for the simulated caves. By contrast, the proposed imaging method more precisely determined the radial distances, azimuths and depths of the simulated caves. The proposed method may broaden the application scope of acoustic remote detection logging in the exploration and development of complex heterogeneous reservoirs.

Borehole acoustic reflection imaging technology is crucial for evaluating fractured reservoirs. When a borehole intersects a fracture surface, the receivers capture not only the reflected waves from near-borehole fractures but also the reflected signals of borehole mode waves originating at the borehole–fracture intersection. The latter constitutes an interference signal in acoustic reflection imaging. To resolve this issue, we numerically simulated the monopole acoustic logging response under two scenarios: with and without borehole–fracture intersection. We then analyzed the waveform differences between the reflections of the borehole mode waves and those from near-borehole fractures. The results show that, in fixed-offset waveforms, the slope of the borehole mode wave reflections is small—approximately half the velocity of the direct waves—while the apparent velocity is nearly identical to that of the direct waves. In contrast, the slope of the reflections from near-borehole fractures is comparatively large. The slope difference between the two types of reflected waves is ∼58

Shock-tube core experiments have provided an important finding, that is, the low frequency acoustic field generated by planar shock waves can induce pure Stoneley waves in a borehole, with their amplitude attenuation demonstrating a definite correlation with fracture width and permeability. Accordingly, a method was proposed to transmit low frequency planar shock waves in a borehole through axially polarized axial vibration, thereby continuously inducing pure Stoneley waves. Equations were also derived for calculating fracture width and permeability from Stoneley wave amplitude attenuation. Moreover, the permeability logging prototype was successfully developed, together with acquisition and processing software incorporating amplitude-attenuation extraction and permeability calculation. The operability, stability, and measurement performance of the logging tool were tested and verified in two standard wells, R91 and LS2. In the 10 000-m extra-deep well SDTK1 in the Tarim Basin, matrix and fracture permeability curves of extra-deep carbonate formations were obtained in a single downhole logging. The results were immediately calibrated with the data of quasi-in-situ nuclear magnetic resonance (NMR) permeability measurement on full-diameter drilling cores taken from the same interval of the well. The results show that the proposed method performs well in quantitative permeability evaluation of extra-deep carbonate reservoirs and provides a new technical approach for permeability logging evaluation in other types of reservoirs. This theoretical and technological breakthrough provides an innovative means for quantitative permeability evaluation in reservoir logging.

Achieving p-type conductivity in ZnO is a key challenge due to unfavorable valence band alignment that causes acceptor dopants to form deep states. Using density functional theory (PBEsol for bulk structure and electronic structure, PBE for slab and molecular-dynamics calculations, with HSE06 single-point verification), we investigate the electronic structure of three ZnO polymorphs: wurtzite (P63mc), rocksalt (Fm3̄m), and ZnO2 pyrite (Pa3̄). We apply two bulk-to-bulk schemes (an empirical Zn-3d-semi-core internal reference motivated by core-level alignment approaches, and a Tersoff–Schleife branch-point-energy estimator) together with an independent slab-vacuum alignment computed in this work using non-polar surface terminations (wurtzite m-plane, rocksalt (100), pyrite (100)), and cross-validate against the published HSE06 result of Goyal and Stevanović 2018. On the slab-vacuum scale (this work, PBE on non-polar slabs) the rocksalt VBM lies +0.7eV above wurtzite at the relaxed–relaxed pairing, with a protocol spread of +0.25 to +0.88eV across the three slab pairings (frozen–frozen, relaxed–relaxed, and asymmetric mixed); the independent HSE06+α-tuned slab-vacuum result of Goyal et al. 2018, +1.6eV, agrees in sign and ordering. On the Zn-3d-aligned scale (this work) the offset is essentially zero (+0.03eV), and the branch-point alignment gives −0.80eV; the offset is therefore reference-dependent and we report it transparently across all three schemes. The qualitative finding — rocksalt VBM raised relative to wurtzite on the photoemission/vacuum scale, mechanism for enhanced p-type dopability — is robust on that scale. Wurtzite is the ground state (−4.853 eV/atom), with rocksalt 110 meV/atom higher and ZnO2 pyrite 64 meV/atom above; ab initio molecular dynamics at 300 K confirms dynamical stability of the wurtzite, rocksalt, and zinc-blende phases (ZnO2 pyrite is excluded from the AIMD set because it experimentally decomposes above 200 °C and is treated separately as kinetically metastable). The PBEsol band gaps are 0.69 eV (wurtzite), 0.79 eV (rocksalt), and 2.16 eV (ZnO2); HSE06 single-points give 2.52, 2.64, and 4.41 eV respectively, preserving the qualitative gap ordering. These findings establish structure–property relationships governing p-type doping in ZnO polymorphs.

PurposeThe purpose of this paper is to design, build and validate a cost-effective triaxial MEMS seismometer (TerraSense), aiming to provide a practical monitoring tool for urban subsurface risk assessment during construction and operation.Design/methodology/approachTerraSense consists of both hardware and client software components. The hardware includes sensors, acquisition circuits and a microcontroller, peripheral and communication circuits, as well as a power supply system. The client software provides instrument parameter configuration, real-time data display and functions such as time or frequency-domain analysis and filtering. In addition, to evaluate TerraSense's performance, laboratory shaker tables were used to test the instrument's time-domain linearity and frequency-domain response characteristics. Furthermore, the horizontal-to-vertical spectral ratio method was applied in urban shallow geological environments for field measurements to verify its capability in detecting shallow geological anomalies.FindingsTerraSense demonstrates stable and reliable spectral response characteristics in both the time and frequency domains. Power spectral analysis confirms that the instrument records horizontal and vertical seismic components with sufficient accuracy to support the identification of shallow geological anomalies using the horizontal-to-vertical spectral ratio method. Results from both shaker table tests and field measurements indicate that TerraSense is capable of effectively resolving typical shallow subsurface anomalies in urban environments, supporting its applicability for preliminary underground risk assessment in engineering and construction contexts.Originality/valueThis study proposes a cost-effective three-axis seismometer based on microelectromechanical systems, providing a reliable solution for shallow geological detection in urban environments.

With increase in the number of operations involving relief wells, radial wells, U-shaped wells, and other complex well structures, challenges such as collision prevention, obstacle bypassing, and adjacent-well connectivity achievement during drilling have become inevitable. These challenges necessitate a technology that can accurately detect adjacent wells in real time during drilling operations. As current borehole acoustic reflection imaging technology heavily relies on cable-based logging, it cannot perform real-time detection of adjacent wells during drilling, thereby limiting the drilling efficiency. This study proposes a new adjacent-well-acoustic-detection-while-drilling method that integrates wireline borehole acoustic reflection imaging with drilling technology, along with an adjacent-well imaging method based on compressed sensing (CS). Together, these methods enable high-resolution, real-time detection of the adjacent target wells during drilling, ensuring safe and efficient underground drilling operations. The finite-difference method was used to simulate three-dimensional numerical models under drilling conditions for two scenarios-with and without target wells adjacent to the drilling well. Experimental validation was conducted in a water tank using an adjacent-well-acoustic-detection-while-drilling tool. The simulated target well was imaged using the CS method, and the imaging results were compared with those obtained from numerical and physical simulations, thereby validating the feasibility of the proposed acoustic detection and imaging methods. The results demonstrate that as the radial distance from the target well increases, the PP echo exhibits delayed arrival times and approaches a plane wave while exhibiting amplitude attenuation. Conversely, a linear increase in the target well diameter advances the PP echo arrival time and enhances its amplitude proportionally. When the target and drilling wells are approximately parallel with a small intersection angle, PP echoes yield better detection results than SS echoes; when the wells are coplanar with a large intersection angle, SS echoes provide better detection results. The receiver element aligned with the target well's azimuth detects all echo modes with the earliest arrival times and highest amplitudes. The adjacent-well imaging method based on CS offers very high spatial resolution, with target wells appearing as local amplitude maxima. This feature enables the precise determination of their azimuth and inclination relative to the drilling wells. The findings offer a solid physical and methodological foundation for real-time detection of adjacent wells during drilling operations and demonstrate enormous theoretical and engineering application potential. (c) 2026 Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Borehole acoustic reflection imaging utilizes acoustic waves to identify well-side anomalies, but accurately obtaining the azimuth is an ongoing problem. In this study, a mathematical model was developed for the echo signal from a well-side anomaly recorded by a downhole cylindrical receiver array utilizing acoustic pressure sensors. The model was used to propose a 3-D multiple signal classification (3D-MUSIC) method for calculating the azimuth of the well-side anomaly based on the orthogonality of the echo signal subspace and noise subspace. Then, a mathematical model was derived for the signal recorded by a downhole receiver array utilizing acoustic vector sensors, which provide information on both the acoustic pressure and particle velocity. This model was used to propose a 3-D acoustic vector array MUSIC (3D-AVA-MUSIC) method for calculating the azimuth of a well-side anomaly with improved noise suppression and detection accuracy. Numerical simulations, physical simulations, and field tests were conducted to evaluate the performances of the proposed methods compared with existing methods. Compared with the existing downhole beamforming and 3-D slowness time coherence (3D-STC) methods, 3D-MUSIC, and 3D-AVA-MUSIC demonstrated higher accuracy. In addition, 3D-AVA-MUSIC effectively utilized acoustic pressure and particle velocity information to perform better than 3D-MUSIC.

Robots are increasingly integral across various sectors due to their efficiency and superior capabilities, which enable performance beyond human potential. However, the development of robotic systems often conflicts with the sustainable development goals set by the United Nations, as they generate considerable nondegradable waste and organic/inorganic pollutants throughout their life cycle. In this paper, we introduce a dual closed-loop robotic system that integrates biodegradable, sustainable materials such as plasticized cellulose films and NaCl-infused ionic conductive gelatin organogels. These materials undergo a closed-loop ecological cycle from processing to biodegradation, contributing to new growth, while the self-sensing, origami-based robot supports a seamless human-in-the-loop teleoperation system. This innovative approach represents a paradigm shift in the application of soft robotic systems, offering a path toward a more sustainable future by aligning advanced robotic functionalities with environmental stewardship.

Summary In the current stage, acoustic logging tool test benches are almost specifically designed for individual logging tools. In order to improve the universality, scalability, and inheritability of the acoustic logging tool testing bench, this paper designs a comprehensive test bench for acoustic logging tools based on Field-Programmable Gate Array (FPGA). It breaks through the traditional architecture of the acoustic logging tool testing bench and is developed based on an embedded bench, with FPGA as the control core and the business communication core. Multiple interface modules are developed, including Ethernet, Secure Digital Input and Output (SDIO) interface, and RapidIO interface. The Ethernet interface is mainly used to connect with PC software for command transmission and data uploading, the SDIO interface is mainly used for downhole data storage, and the RapidIO interface is mainly used for high-speed acoustic imaging logging. Experimental results show that the transmission speed of the comprehensive testing bench is up to 1.25 Gbps and the bit error rate as low as 10−4. The pressure testing effect is good. The results indicate that the comprehensive testing platform meets the debugging requirements of the acoustic logging tool, saves costs, and achieves high-speed and stable data transmission.

It has been reported that monolayered BSb has excellent carrier mobility. In this work, we investigate the effect of strain on the electronic properties of a BSb monolayer and the transport properties of related devices based on density functional theory calculations combined with the nonequilibrium Green's function method. We find that under biaxial tensile strain, the direct bandgap of the BSb monolayer continuously increases and turns to an indirect gap at strain strength 9 = 7.2%. The indirect gap is closed at 9 = 10.1%. Such a semiconductor-metal transition is caused by strain-induced change of orbital distribution in the BSb monolayer. Additionally, we investigate the transport properties of transistor devices based on monolayered BSb. In the output characteristics, a striking negative differential conductance is demonstrated. In the transfer characteristics, we find that the subthreshold swing and the ratio of maximum to minimum drain current can be enhanced by the tensile strain 9 <= 5%. These features can be understood from the strain-induced change of band gap and the effect of the gate and bias voltages on the effective barrier height in the channel region. Our findings indicate potential applications of BSb monolayer in nanoelectronics.

A borehole azimuthal acoustic-reflection imaging logging tool is equipped with several acoustic receiver stations evenly placed along the axial axis, each containing several azimuthal receiver elements evenly distributed around the circumference. These elements can obtain acoustic-waveform data from different source-receiver distances and azimuths in downhole measurements, which can be used to evaluate geologic structures within tens of meters from a well. Current imaging methods often suffer from widespread artifacts in the circumferential direction when imaging anomalies exist near the well, leading to low accuracy in azimuthal measurements, low value of the imaging signal-to-noise ratio (S/N), and difficulty in meeting the field application needs. We develop a 3D imaging technique based on the acoustic pressure-particle-velocity correlation. We comprehensively use more measurement information and the directional sensitivity of particle-velocity sensors to improve the target azimuthal detection performance and imaging S/N. Our technique is comprehensively described based on waveform data obtained through finite-difference numerical simulation. Then, this technique is applied to experimental testing when there is a target well near the measurement well, and good verification results are obtained. Finally, we apply the technique to process field logging data, obtaining azimuthal and spatial-position information about geologic structures in the formation surrounding the measurement well. The obtained imaging results are compared with logging data processing results obtained using borehole dipole S-wave reflection imaging and microresistivity imaging. The results indicate that compared with 3D spatial-scanning imaging using acoustic-pressure-waveform similarity coefficients, our technique suppresses widespread artifacts of false azimuths and exhibits better azimuthal detection performance for anomalies near the well. Thus, the comprehensive use of acoustic pressure and particle-velocity information in borehole acoustic fields offers improved noise immunity and imaging S/Ns, which is beneficial for detecting weak waveform signals.

Low-frequency acoustic logging transducers are pivotal to far-acoustic imaging logging technology and permeability logging technology. This study presents a monopole acoustic transducer driven by electromagnetic force, exploiting the low-frequency vibration characteristics of a flextensional shell. Finite element simulations were employed to evaluate multiple magnetic circuit configurations under dimensional constraints typical of logging tools. An inner magnet circuit was selected and optimized through parametric analysis. Concurrently, the vibration shell was designed and simulated under borehole conditions, accompanied by the development of a dedicated excitation circuit. The fabricated prototype (64 mm outer diameter, 154 mm height, 100 mm shell height) demonstrated operation frequency at 1300 Hz with a sound pressure level of approximately 150 dB and uniform circumferential radiation, satisfying the requirements of logging applications.

The logging-while-drilling (LWD) acoustic logging instrument is pivotal in unconventional oil and gas exploration, and in providing real-time assessments of subsurface formations. The acquisition system, a core component of the LWD acoustic logging suite, is tasked with capturing, transmitting, and processing acoustic signals from the formation, which directly affects the accuracy and timeliness of the logging data. Recognizing the constraints of current LWD acquisition systems, including limited data collection capabilities and inadequate precision, this study introduces an FPGA-based multi-node data acquisition system for LWD acoustic logging. This system increases sampling density and data accuracy, leading to a more comprehensive collection of formation information. The multi-node acquisition system is composed primarily of a main control circuit board and several acquisition circuit boards, all connected via an RS485 bus. The Field-Programmable Gate Array (FPGA) is utilized to develop the acquisition circuit board’s firmware, offering adjustable control over parameters, such as the AD7380’s operational mode, sampling rate, and depth, facilitating real-time and concurrent acquisition and storage of formation acoustic signals. The main control board communicates with the acquisition boards via the RS485 bus, issuing commands to enable autonomous data collection and transfer from each board, thus enhancing the system’s reliability and scalability. Experimental results confirm the system’s capacity to efficiently capture waveform signals and upload them in real-time, underscoring its dependability and timeliness. The findings suggest that the system is capable of high-speed, real-time acquisition and processing of acoustic signals, offering robust technical support for the continued application of LWD acoustic logging instruments.

Extracting head waves and subsequently uploading their results from the downhole to the surface system in real time could improve the real-time guidance of ultrasonic imaging logging while drilling (UILWD) for drilling operations. To realize the downhole real-time extraction of head waves in this logging, three aspects were explored in this study. First, an improved energy ratio head-wave arrival extraction algorithm based on the weighting coefficients and characteristic functions, along with an amplitude detection method relying on peak-to-peak values, was proposed. Second, an echo reception pre-processing analog circuit and a digital signal processing circuit based on FPGA were designed. A pipeline algorithm was developed in FPGA to extract the arrival time and amplitude of the head wave. Finally, software simulations, laboratory tests, and field experiments related to this method were conducted. Our results showed that the real-time head-wave extraction method demonstrated a strong anti-noise ability in real time. The maximum relative error of the arrival time was less than 5%. The relative error of the amplitude was acceptable, and 90% of this value was within 5%. Through the measurement, the time of processing a single-channel waveform by a downhole algorithm was less than 15 ms, thus meeting the requirements for the real-time processing of downholes.

Abstract The acoustoelectric effect logging detector can achieve downhole acoustoelectric effect measurement, but the excitation of the acoustic transducer can generate significant electromagnetic interference (EMI) signals, it is difficult to effectively measure weak converted signals of acoustoelectric effect underground. The EMI problem of acoustoelectric effect logging detectors can be solved by studying EMI characteristics. Based on the analysis of the structure, measurement function, and measured interference signals of the receiving electrodes of the detector, the EMI sources, coupling paths, and sensitive components in the detector were studied. The basic process of EMI generated by high-voltage pulse excitation source of acoustic transducer is analysed, and two electromagnetic coupling interference analysis models for detectors, namely conductive coupling and borehole electromagnetic coupling, are established. This study can provide a fundamental method and reference for electromagnetic compatibility analysis of acoustoelectric effect logging detectors.

This article reports on the successful downhole testing of the prototype permeability logging instrument, developed by the Li Ning Innovation Team of PetroChina. The test was carried out on 3 March 2024 in the Ren 91 standard well in Huabei (North China). In this article, we analysed the instrument characteristics of porosity logging measurement, saturation logging measurement, and permeability logging measurement in three stages of development, as well as the current research status of continuous depth-permeability measurement in the wellbore formations. We highlighted the basic principle of permeability logging measurement with Stoneley waves and pointed out the main challenges in the development of permeability logging measurement devices and on-site application research.

LWD（Logging While Drilling） ultrasonic imaging requires circumferential scanning imaging through the rotation of the drill collar. In order to improve the azimuthal coverage of LWD ultrasonic imaging in the circumferential imaging measurement, multiple transducers need to be installed for measurement at the same time, and the inconsistent response of the transducers will produce wrong imaging measurement results. This paper studies the response characteristics of LWD ultrasonic imaging transducers through experimental measurement. The experimental test system is mainly composed of high-precision positioning control system, PXI acquisition system, needle hydrophone, Olympus 5077PR signal source, signal converter, objective table, oscilloscope, etc., and it is a small acoustic positioning and measurement system with 4 degrees of freedom. The experiment mainly includes the measurement of axial sound field and directivity of ultrasonic transducer. The axial sound field of the ultrasonic transducer is measured, and the far-near field critical distance and amplitude response characteristics of the transducer are obtained. The experiment shows that the far-near field critical distance of the transducer is about 3.25 cm, and the amplitude response characteristics of each transducer are consistent. The directivity of the transducer is measured, the result shows that the 3 dB angular width is about 12°, and the transducers have good focusing characteristics. This study provides an effective method to evaluate ultrasonic imaging logging transducers, which provides a basis for the matching selection of transducers in the process of tool development, and provides a strong support for the development of ultrasonic imaging logging tools.

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.

方位远探测声波测井技术在近年来得到了快速发展.数据采集控制软件是测井仪器系统的重要功能模块,其主要功能是完成地面采集控制平台与井下仪器的实时命令控制与数据传输.方位远探测声波测井仪数据采集控制软件模块以仪器库的形式挂接到成像测井系统,软件主要由仪器初始化、数据采集、数据分析及处理、仪器参数设置、下发命令封装、文件操作、实时波形绘图显示、实时波形处理、数据回放、帮助系统等部分组成.在程序设计中采用了多线程编程技术,提高与测井主控平台进行交互的时效性以及程序的响应速度.实验室及现场测试表明,方位远探测声波测井仪数据采集控制软件的总体及各个功能模块运行稳定,能够完成现场应用过程中对仪器的控制、数据读取、数据分析及处理、文件记录以及与现场测井采集控制平台的数据接口等需求,为仪器的进一步功能优化升级和现场应用提供了基础.

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.