Search Results (11,664)

The Permian Taiyuan and Shanxi Formations of the Upper Paleozoic in the Ordos Basin are the primary source rock sequences for tight sandstone gas. The core problem lies in the uncertainty surrounding the gas generation process at the overmature stage. To clarify hydrocarbon generation processes and the potential of coal, carbonaceous mudstone and dark mudstone, we integrate basin modeling and hydrocarbon generation pyrolysis thermal simulation experiments. Using PetroMod software and measured well data on vitrinite reflectance (Ro), total organic carbon (TOC), T_max and hydrocarbon generation potential (S₁ + S₂), we quantitatively reconstruct the burial, thermal, maturity and hydrocarbon evolution histories of the southern Ordos Basin. The results indicate that the main oil generation window is concentrated at 400 °C, and gas yield increases continuously from 350 °C to 700 °C without a peak, showing that coal and carbonaceous mudstone still have considerable hydrocarbon generation potential under extreme high-temperature conditions. Combining the hydrocarbon generation ratio, rock density and TOC data, coal is identified as the predominant source rock in the southern Ordos Basin. This study provides a scientific basis for tight gas exploration in cratonic basins, enhances the understanding of gas generation in coal-bearing source rocks, and offers a new perspective for oil and gas resource evaluation. Full article

Deep unconventional oil and gas reservoirs are critical to hydrocarbon exploration and development in China. However, their complex geological and petrophysical features, including high temperature, high pressure, high salinity, multiple pressure systems, and intricate pore–fracture structures, make them highly susceptible to formation damage during drilling, completion, stimulation, and production. Effective reservoir protection is therefore essential for minimizing damage and improving development efficiency. This paper systematically reviews recent advances in reservoir protection for deep unconventional reservoirs, with a focus on evaluation methods and protective materials. Laboratory evaluation methods, including permeability recovery, nuclear magnetic resonance, pressure decay, and spontaneous imbibition, together with field-based approaches such as well testing and production decline analysis, are summarized and assessed for their applicability to complex damage characterization. Major damage mechanisms, including liquid-phase trapping, solid invasion, sensitivity damage, stress sensitivity, and wettability alteration, are analyzed with emphasis on working fluid–reservoir interactions under multi-field coupling conditions. Recent progress in protective materials is also reviewed, covering polymer-based materials such as gel sealing agents, delayed-swelling hydrogels, water-/oil-soluble temporary plugging agents, and film-forming polymers, as well as ultrafine CaCO₃ and fiber-based materials. In addition, related protection technologies, including temporary plugging, film-forming fluid-loss control, underbalanced drilling, and low-damage completion fluids, are discussed. Existing models developed for conventional sandstone reservoirs are insufficient for deep unconventional systems. Future research should prioritize integrated evaluation and protection methods tailored to deep tight, shale, and fractured–vuggy carbonate reservoirs. This review provides a basis for understanding complex damage mechanisms, developing functional protective materials, and advancing integrated reservoir protection technologies for the efficient development of deep unconventional resources. Full article

Background/Objectives: Lavandula cariensis species is cultivated uncommonly in the western region of Turkey. The colloquial appellations avayianos, karabasi, and myra are used to refer to the L. cariensis plant. The essential oil of L. cariensis was studied for its potential antiglaucoma, antioxidant, antidiabetic, and acetylcholinesterase inhibitory effects. Methods: The inhibitory effect of the essential oil of L. cariensis on the acetylcholinesterase (AChE), carbonic anhydrase II (CA II), and α-amylase enzymes was determined. Therefore, chemical profiles of L. cariensis’ essential oil were identified using Gas Chromatography Mass Spectrometry (GC-MS) and as Chromatography with Flame Ionization Detection (GC-FID) analyses. Results: Camphor (39.73%), fenchone (19.49%), exobornyl acetate (6.81%), camphene (5.49%), and eucalyptol (5.49%) were the most abundant compounds in L. cariensis essential oil. Radical scavenging effect of the essential oil of L. cariensis was examined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC₅₀: 231.0 ± 0.094 μg/mL) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) (IC₅₀: 7.45 ± 0.013 μg/mL) radicals. Also, the ferric ions (Fe³⁺), cupric ions (Cu²⁺), and Fe³⁺-2,4,6-tri(2-pyridyl)-S-triazine (TPTZ) complex reducing capabilities were studied. Additionally, essential oil of L. cariensis indicated a comparable level of inhibition towards hCA II (IC₅₀: 276.42 μg/mL), AChE (IC₅₀: 14.22 μg/mL), and α-amylase (IC₅₀: 475.63 μg/mL) enzymes. Conclusions: The evaluation of the antioxidant capabilities and enzyme inhibition profiling of the essential oil of L. cariensis will be made possible by this comprehensive study, which serves as a springboard for further research. The essential oil of L. cariensis demonstrated enzyme-inhibitory activities against target enzymes associated with Alzheimer’s disease, diabetes, and glaucoma. Also, this study’s in vitro inhibition suggests promising prospects. Full article

In recent years, wars have gradually increased the risk of marine oil spill accidents. Marine oil spill monitoring becomes more and more important for preventing marine oil pollution. The Chinese Zhuhai-1 satellite can capture abundant spectral reflectance signals. It is a significant way of detecting marine oil spills. Most of the traditional oil spill detection methods only used a small amount of spectral information. It made it difficult identify oil spills accurately from the inhomogeneous marine environment. In order to mine the key differential spectral information of oil slicks, inspired by the encoding method of spectral DNA, an advanced spectral DNA encoding (ASDE) strategy was proposed to describe the spectral details in Zhuhai-1 images. On this basis, two kinds of key spectral information extraction methods were proposed to mine the spectral genes of oil slicks. Finally, the extracted spectral genes were used to detect the marine oil spills. Three Zhuhai-1 satellite images were used to validate the performance of the proposed method based on ASDE strategy. The experimental results indicated that the proposed method could precisely describe the spectral differences in oil slicks and seawater in Zhuhai-1 images. In addition, the extracted spectral genes could detect marine oil spills correctly. Full article

Salt rock exhibits pronounced viscoelastic creep, continuously imposing radial extrusion loads on casing and threatening long-term well integrity. Field observations in the Missan Oilfield, Iraq, show that casing damage is concentrated near salt–non-salt interfaces, where lithologic contrasts intensify stress redistribution and mechanical coupling. This study integrates triaxial creep experiments, a calibrated modified Burgers model, UMAT implementation, and three-dimensional finite element simulations to investigate casing stress evolution and failure mechanisms. The calibrated model reproduces salt rock creep with a maximum relative strain error of 16.8%. Results show that post-cementing salt creep amplifies non-uniform radial loading at the interface, causing progressive casing stress concentration. At low inclination, the interface–casing intersection evolves into an elliptical annulus; the circumferential variation in equivalent wall thickness and stress-peak migration jointly weaken local stress concentration. However, when the inclination angle reaches approximately 45° at β = 0°, the peak Mises stress begins to exceed that under the vertical-well condition. When α ≥ 65°, the peak stress no longer decreases monotonically with azimuth but exhibits a decrease–increase trend. This indicates that eccentric loading and the additional bending moment dominate the transition from radial extrusion to coupled bending–shear–extrusion loading. A casing stress risk map and grade-selection chart are developed to support casing design in salt-interbedded formations. Full article

As core structural components for deep-sea oil and gas exploitation, deep-sea risers are continuously subjected to wind, wave, and current loads, which readily induce vortex-induced vibration (VIV) and further trigger structural fatigue damage. Furthermore, the progressive exploitation of deepwater and ultra-deepwater oil and gas resources has exacerbated the complexity and risk of riser VIV, rendering it a critical engineering problem that urgently requires effective solutions. This paper presents a comprehensive review of numerical studies on deep-sea riser VIV, systematically elaborating the fundamental principles, research advances, and application scenarios of three mainstream numerical approaches: semi-empirical models, computational fluid dynamics (CFD) models, and computational structural dynamics (CSD) models. The respective accuracy advantages and inherent limitations of each numerical method are thoroughly analyzed. Additionally, this review focuses on key research hotspots and challenging issues, including VIV responses of flexible risers, dynamic fluid–structure boundary coupling, internal–external flow coupling effects, wake interference of multi-riser systems, efficient VIV prediction, and vibration suppression optimization. The current technical bottlenecks in existing research are clarified. This study aims to provide a systematic theoretical framework and methodological reference for subsequent numerical investigations and engineering applications of riser VIV, and offer technical support for the optimal structural design and safety risk prevention of deep-sea riser systems. Full article

This study presents a transient computational fluid dynamics (CFD) analysis of dielectric flow behaviour and debris transport in micro-EDM milling, considering the effects of dielectric properties, inter-electrode gap (IEG) size (20–30 µm), and tool rotational speed (400–850 rpm). Four dielectric media, nitrogen gas, deionized water, HEDMA111 EDM oil, and sunflower seed oil, were investigated using a two-dimensional FEM-based model coupled with particle tracking simulations to evaluate debris mobility within the machining region. The results demonstrate that dielectric properties, particularly viscosity, strongly influence hydrodynamic behaviour and particle transport within the IEG. Under the adopted equal mass flow rate condition, nitrogen gas exhibited the highest flow velocities and the fastest debris evacuation due to the combined effects of its low viscosity and the resulting higher inlet velocity. Deionized water and HEDMA111 oil exhibit comparable intermediate behaviour, indicating that moderate viscosity variations within liquid dielectrics do not significantly alter the overall flow regime. In contrast, sunflower seed oil generates the most damped flow conditions, with reduced velocities and prolonged particle residence due to increased viscous resistance. Variations in IEG size produce only minor changes in evacuation efficiency compared with the dominant influence of dielectric properties, while tool rotational speed primarily affects velocity magnitude without altering qualitative transport behaviour. Full article

Exploitation of deep (>4000 m) tight geothermal reservoirs is constrained by low native permeability and premature thermal breakthrough, limiting sustainable heat recovery. Here, we investigate THM (thermo–hydro–mechanical) controls on fluid flow and heat transport during cold-water reinjection in deep tight sandstone reservoirs through an integrated framework linking two-dimensional mechanistic analysis with three-dimensional field-scale modeling. A two-dimensional thermo-poroelastic model reveals that strong thermal contrasts induced by cold-fluid injection cause contraction of the rock framework and transient pore-space dilation under confinement, producing short-term permeability enhancement. This process alters local flow capacity and redirects early cold-front migration, with persistent impacts on subsequent heat transport. Field-scale simulations further quantify the coupled effects of well spacing and reinjection temperature on thermal breakthrough, defined as a 1 °C decline in production-well temperature. Increased well spacing delays cold-front arrival and significantly retards breakthrough, whereas lower reinjection temperature enhances early heat extraction but accelerates convective transport, leading to earlier breakthrough. The combination of thermally enhanced permeability and intensified convection promotes preferential flow channels, increasing breakthrough risk. Balancing thermal-breakthrough delay against the heat-extraction driving force, the simulations delineate a favorable engineering window for the investigated conditions and clarify how cooling-sensitive permeability evolution affects preferential flow and reservoir-scale thermal response. Full article

Full-duplex acoustic telemetry is important for real-time bidirectional measurement and control in intelligent coiled-tubing operations, but its reliability in deep horizontal wells is limited by long-range dispersion, asymmetric flow-induced noise, and severe near-end self-interference. This study proposes an orthogonal frequency-band planning and synergistic interference suppression method for full-duplex acoustic communication in coiled tubing. A dispersion model and an asymmetric attenuation model were first established for a fluid-filled coiled-tubing cylindrical-shell waveguide to characterize the physical transmission constraints. A multiphysics multi-objective cost function was then formulated by considering dispersion flatness, channel attenuation, asymmetric noise adaptability, and spectral isolation, and an improved simulated annealing algorithm was used to optimize the uplink and downlink frequency bands. In addition, a three-stage suppression architecture integrating mechanical decoupling, physical-layer frequency isolation, and CEEMDAN–wavelet denoising was developed to reduce self-interference and residual nonstationary noise. Full-scale experiments on a 457.2 m coiled-tubing surface circulation system showed that the proposed method improved the output signal-to-interference-plus-noise ratio from −15 dB to 18.5 dB and maintained a bit error rate below 1.2 × 10⁻⁴ at 400 L/min. These results indicate that the proposed approach can enhance the robustness of full-duplex acoustic telemetry under strong flow-induced noise. Full article

This study evaluates the life cycle assessment (LCA) of Lufenuron 50-EC pesticide adsorption from aqueous solution using oil palm shell (OPS)-derived activated carbon produced through two activation routes: physical and chemical. The assessment covers environmental impacts associated with feedstock collection, transportation, pre-processing, and post-processing stages involved in producing activated carbon for pesticide removal. The cradle-to-grave LCA technique was applied using the ELCD 3.2 Greendelta v2.18 database and processed with OpenLCA v2.4 using CML-IA baseline method to perform the quantitative life cycle impact assessment. The results for treating 1 m³ of contaminated water show that physical activation route (Route 1) generates a higher environmental burden across all evaluated impact categories compared to chemical route (Route 2). Notably, global warming potential (GWP) reached 117.62 kg CO₂ eq for Route 1 compared to 75.86 kg CO₂ eq for Route 2. This represents a 35.5% reduction with the chemical route, suggesting that the high energy demand associated with thermal process in physical activation generates more significant greenhouse gas emissions. Overall, this study helped identify critical performance points and opportunities for improvement in converting the OPS to an activated carbon transformation process and its application in pesticide contamination control. Full article

With the expansion of ammonia energy applications, long-distance liquid ammonia pipelines are expected to support large-scale cross-regional ammonia transport. In the liquid ammonia pipeline commissioning process, gaseous ammonia purging involves ammonia–nitrogen mixing and possible liquefaction, while liquid ammonia injection may induce flashing and severe local cooling, all of which can affect commissioning safety. To characterize these thermodynamic phenomena, a transient gas–liquid two-phase flow model was established and validated using OLGA 2022.1.0 software for simulating the long-distance liquid ammonia pipeline commissioning. The model adopts the cross-sectionally averaged one-dimensional approach. A volume-corrected Soave–Redlich–Kwong (SRK) equation of state for ammonia was adapted, validated, and used to generate OLGA-compatible thermodynamic property tables. The results show that, during gaseous ammonia purging, a higher flowrate shortens the displacement time by accelerating nitrogen removal, and this effect is more pronounced at higher ambient temperatures due to enhanced molecular diffusion. Along the pipeline, pressure gradually decreases from frictional resistance, with a steeper drop near the outlet caused by gas acceleration, and temperature gradually approaches ambient through heat exchange with the pipe wall and surrounding soil. A high gaseous ammonia flowrate can cause partial liquefaction, regasification, and temperature fluctuations. During liquid ammonia injection, local condensation and slight liquid accumulation occur before the liquid front arrives, and the low-temperature region moves with the liquid front. The liquid ammonia mass flowrate has the strongest influence on the injection process, as it reduces the completion time but increases the outlet temperature, outlet pressure, and the low-temperature risk downstream of the valve. Therefore, it should be controlled within an appropriate range to balance efficiency and low-temperature safety risks. This work provides a rapid and efficient prediction model for key thermo-hydraulic parameters during liquid ammonia pipeline commissioning, and the overall analyses offer insights for on-site process design and safety control. Full article

Bio-based coatings enriched with essential oils (EOs) represent a promising alternative to synthetic preservatives to extend strawberries’ shelf-life. This study evaluated the effects of chitosan (CHT) formulations containing three selected EOs (Illicium verum, Citrus sinensis, and Citrus limon) on the volatile profile, sensory quality, and antifungal activity of strawberry fruits. Volatile emissions were characterized by Headspace Solid Phase Micro-Extraction/Gas Chromatography-Mass Spectrometry, while sensory properties were assessed using Quantitative Descriptive Analysis. Antifungal activity was evaluated both in vitro and in vivo against Botrytis cinerea. Chitosan alone slightly modified the volatile profile, while EO-enriched coatings induced marked and concentration-dependent changes, reflecting the chemical composition of the incorporated EOs. Among the tested formulations, CHT combined with 1% C. sinensis EO provided the best balance between preservation of the characteristic strawberry aroma and overall sensory acceptance. In vitro assays showed that EO volatiles, particularly from C. sinensis and I. verum, significantly inhibited fungal growth, while diffusible compounds were less effective. In vivo, EO-containing coatings reduced disease incidence and severity by approximately 50%. These findings highlight the potential of CHT–EO coatings as sustainable options for postharvest preservation, although optimization of EO type and concentration is crucial to balance sensory quality and antimicrobial efficacy. Full article

To address the widespread issue of abnormally high pump pressure during hydraulic fracturing of deep-to-ultra-deep reservoirs (burial depth > 4500 m) in the Junggar Basin, this study systematically reveals the mechanical mechanism underlying this phenomenon by integrating well logging curve analysis and elastoplastic mechanics theory. Statistical results demonstrate that the actual fracture initiation pressure of 60% of wells in the target block is significantly higher than the values predicted by traditional elastic theory, primarily attributed to plastic yielding and stress concentration effects around perforations induced by high in situ stress. An elastoplastic rock fracture initiation pressure model is established based on the Mohr–Coulomb criterion and the plastic zone radius criterion, which is applied to predict the fracture initiation pressure of selected wells in the target block. The relative error between the model predictions and field measurements is less than 2%, significantly improving the prediction accuracy of fracture initiation pressure in deep-to-ultra-deep formations. This provides precise guidance for subsequent optimization of operational parameters and selection of pressure ratings for wellhead equipment. The study further clarifies that in situ stress difference, rock yield stress, and the power-law hardening exponent are the key factors controlling the transition of fracture initiation modes. To mitigate the high pump pressure challenge in deep-to-ultra-deep reservoir fracturing, the field application of weighted fracturing fluid effectively increases the wellbore hydrostatic column pressure, reduces wellhead operational pressure, and ensures construction safety. The findings of this study provide critical theoretical and technical support for achieving the goal of “successful fracture initiation and effective fracture control” in deep-to-ultra-deep reservoir fracturing. Full article

Tight oil and gas reservoirs have become an important alternative to conventional hydrocarbon resources worldwide. They are characterized by dense formations, strong heterogeneity, and the low natural productivity of individual wells, making well pattern deployment and injection–production parameter optimization highly challenging. In real development, tight oil and gas fields usually involve hundreds or even thousands of wells. If each well is analyzed and optimized individually, a large amount of computation is required. Meanwhile, uncertainty in geological models further increases the complexity of development scheme design. Traditional manual adjustment methods based on engineering experience are inefficient and make it difficult to obtain an optimal well pattern suitable for the efficient development of tight oil and gas reservoirs under complex constraints, thus showing obvious limitations. To address these problems, this study first analyzes the strengths, weaknesses, and applicability of existing well placement optimization methods. Based on this analysis, we propose an optimization design method that integrates numerical simulation software for tight oil and gas reservoirs with modern intelligent optimization algorithms, enabling rapid and effective integrated optimization of horizontal well placement and fracturing in tight reservoirs. After being applied to Block X of a tight oil field, this optimization method achieved favorable field results, with an average cumulative oil and gas equivalent production of 31,400 metric tons per well, providing a new approach for the effective development of similar tight oil and gas reservoirs. Full article

Magnetic flux leakage (MFL) testing is a vital non-destructive testing method used to identify defects in oil and gas pipelines and critical components. However, variations in defect geometry and testing conditions can lead to inaccurate data and imbalanced feature distributions, which compromise detection outcomes. To address these challenges, this paper presents a defect classification approach for MFL testing based on generating expansion and the Dual-Channel Vision Transformer (DC-ViT). First, COMSOL finite element software (version 6.1) was used to simulate magnetic flux leakage for different types of pipeline defects. Axial and radial dual-channel signals were extracted to create the initial dataset. Next, a Conditional Variational Autoencoder (CVAE) was used for Generate Expansion to effectively mitigate sample scarcity and defect category imbalance. Finally, the DC-ViT model was constructed and trained using the Generate Expansion dataset as input to achieve multidimensional feature fusion and classification prediction for defects. Experimental results demonstrate 97.97% detection accuracy. The DC-ViT model outperforms traditional convolutional neural networks and single-channel models in terms of accuracy, precision, recall, and F1-score. These results validate the method’s effectiveness and robustness in complex defect scenarios and offer a novel approach to magnetic leakage signal detection. Full article