Impact force refers to a transient phenomenon with a very short-acting time, but a large impulse. Therefore, the detection of impact vibration is critical for the reliability, stability, and overall life of mechanical parts. Accordingly, this paper proposes a method to indirectly characterize the impact force by using an impact stress wave. The LS-DYNA software is utilized to establish the model of a ball impacting the steel plate, and the impact force of the ball and the impact response of the detection point are obtained through explicit dynamic finite element analysis. In addition, on this basis, a correspondence between the impact force and the impact response is established, and finally, an experimental platform for impact force detection is built for experimental testing. The results obtained by the finite element method are in good agreement with the experimental measurement results, and it can be inferred that the detected piezoelectric signal can be used to characterize the impact force. The method proposed herein can guide the impact resistance design and safety assessment of structures in actual engineering applications.

Production logging (PL) instruments play a pivotal role in the comprehensive management and monitoring of oil and gas reservoirs. These devices facilitate the resolution of complex flow diagnosis challenges throughout the life cycle of hydrocarbon field exploitation. However, the advent of highly deviated well drilling technology has exposed certain limitations inherent in conventional centralized logging sensing techniques. When fluid flow within horizontal wells becomes segregated or even laminar, these traditional methods struggle to accurately decipher the zonal productions of oil, gas, and water. To address this challenge, multi-array production logging tools were developed in the late 1990s. Historically, these tools were characterized by considerable lengths, reaching up to 30 feet for an entire suite incorporating flow speed and holdup sensors that were not always collocated. Despite the integration of multiple sensors, uncertainties in determining flow profiles persisted. In this paper, we propose a novel integrated multi-parameter evaluation method based on measurements from a recently developed ultracompact flow array sensing tool, aimed at enhancing the accuracy of reservoir evaluation. The validity of the multi-parameter method is substantiated through a comparison of the new tool with an industry benchmark array PL tool on the same well. By combining the monitoring results, an optimization strategy for oil and gas extraction is presented, which is expected to improve the oil and gas recovery rate, thereby providing guidance for subsequent extraction endeavors. Moreover, we demonstrate how this innovative integrated workflow significantly enhances energy savings and efficiency, further underlining its value in modern oil and gas field management.

Since light propagation in a multimode fiber (MMF) exhibits visually random and complex scattering patterns due to external interference, this study numerically models temperature and curvature through the finite element method in order to understand the complex interactions between the inputs and outputs of an optical fiber under conditions of temperature and curvature interference. The systematic analysis of the fiber’s refractive index and bending loss characteristics determined its critical bending radius to be 15 mm. The temperature speckle atlas is plotted to reflect varying bending radii. An optimal end-to-end residual neural network model capable of automatically extracting highly similar scattering features is proposed and validated for the purpose of identifying temperature and curvature scattering maps of MMFs. The viability of the proposed scheme is tested through numerical simulations and experiments, the results of which demonstrate the effectiveness and robustness of the optimized network model.

Shale gas extraction relies on horizontal drilling and multi-stage fracturing that involve intricate flow dynamics. Thus, it is crucial to evaluate the impacts of stress, thermal expansion, and desorption on reservoir matrix deformation, as they cause dynamic porosity and permeability changes. As contemporary simulation techniques struggle to precisely represent these processes, we present a thermo-hydro-mechanical (THM) coupling model that incorporates the dynamic fluctuations in porosity and permeability. The THM model simulates the mechanical deformation, the adsorption, desorption, diffusion, and flow of gas, and the heat transfer among the shale matrix, hydraulic cracks, and wellbore. The finite element method is employed to resolve and corroborate the THM model with production data from the Marcellus shale. Additionally, computational models and orthogonal experiments are employed to evaluate the effects of stress field parameters on gas production and wellbore temperature. Results suggest that the stress field strongly affects gas production and wellbore temperature, and disregarding stress field coupling effects overstates gas production by around 12.9%. Porosity and Langmuir volume correlate positively with wellbore temperature, while permeability, Young’s modulus, Langmuir pressure, thermal expansion coefficient, and adsorption strain exhibit negative correlations. Thus, porosity, permeability, and adsorption strain are the principal factors influencing the wellbore temperature profile. These findings contribute to the accurate simulation and optimization of shale gas reservoir exploitation.

In the oil and gas industry, fiber-optic telemetry is hindered by transmission degradation from high-temperature macro-bend loss. In this study, to address the lack of a unified model, we develop a numerical framework incorporating both bending-dominated effects and thermo-optic modulation. We systematically analyze the coupled responses of multimode (MMF) and single-mode (SMF) fibers at 1.55 μm across varying temperatures (303.15~483.15 K) and bending radii (1~12 mm). Power spectral density (PSD) and phase spectra are utilized to characterize the loss response and explore its modulation mechanisms. Our results indicate that the MMF temperature response is relatively smooth, with a peak magnitude of 10³. In the frequency domain, increased bending raises the MMF PSD main peak by over an order of magnitude, enhancing structural features. While the MMF phase response exhibits a wide dynamic range under tight bending, it becomes unstable in weak modulation regions. Conversely, SMF exhibits more pronounced structural fluctuations (order of 10⁴) but maintains a continuous, smooth phase gradient, demonstrating superior stability. Furthermore, MMF frequency-domain characteristics are highly wavelength-dependent (1.2~2.0 μm), whereas SMF fluctuations remain below 10%, indicating a higher parameter robustness. These findings provide a theoretical foundation for optimizing downhole fiber-optic telemetry selection and signal processing strategies.

This study systematically analyzed thermal interference in fiber-optic telemetry and distributed sensing systems operating in high-temperature downhole environments. Utilizing a thermo-optic theoretical framework, we evaluated the thermally induced attenuation of single-mode (SMF) and multi-mode fibers (MMF) across a temperature range of 303.15–473.15 K. At 473.15 K, the MMF attenuation coefficient (2.5 ×10^-5 dB/m) was significantly lower than that of SMF (1.5 × 10^-3 dB/m). Further analysis indicates that at a wavelength of 1.55 μm, the thermo-optic effect (TOE) significantly narrows the signal bandwidth. While MMF exhibits pronounced temperature-dependent dispersion, SMF phase evolution remains nearly linear. Spectral analysis reveals that the MMF attenuation peak occurs at 1.55 μm, with an amplitude approximately twice that at other wavelengths. Additionally, the SMF mode field diameter (MFD) expands with wavelength but decreases linearly with temperature at a gradient of 0.008 K^-1. These results suggest that although MMF offers lower attenuation, its intense thermally induced dispersion limits long-range performance. In contrast, SMF demonstrates superior phase stability. Consequently, these findings establish a theoretical foundation for fiber selection and temperature compensation design in high-temperature downhole systems.