Search Results (32)

Conventional rock mechanical testing approaches encounter significant limitations when applied to deeply buried fractured formations, constrained by formidable sampling difficulties, prohibitive costs, and intricate specimen preparation demands. This investigation pioneers an innovative nanoindentation-based multiscale methodology (XRD–ED–SEM integration) that revolutionizes the mechanical characterization of dolostone through drill cuttings analysis, effectively bypassing conventional coring requirements. Our integrated approach combines precision surface polishing with advanced indenter calibration protocols, enabling the continuous stiffness method to achieve unprecedented measurement accuracy in determining micromechanical properties—notably an elastic modulus of 119.47 GPa and hardness of 5.88 GPa—while simultaneously resolving complex indentation size effect mechanisms. The methodology reveals three critical advancements: remarkable 92.7% dolomite homogeneity establishes statistically significant elastic modulus–hardness correlations (R² > 0.89), while residual imprint analysis uncovers a unique brittle–plastic interaction mechanism through predominant rhomboid plasticity (84% occurrence) accompanied by microscale radial cracking (2.1–4.8 μm). Particularly noteworthy is the identification of load-dependent property variations, where surface hardening effects and defect interactions cause 28.7% parameter dispersion below 50 mN loads, progressively stabilizing to <8% variance at higher loading regimes. By developing a micro–macro bridging model that correlates nanoindentation results with triaxial test data within a 12% deviation, this work establishes a groundbreaking protocol for carbonate reservoir evaluation using minimal drill cutting material. The demonstrated methodology not only provides crucial insights for optimizing hydraulic fracture designs and wellbore stability assessments, but it also fundamentally transforms microstructural analysis paradigms in geomechanics through its successful application of nanoindentation technology to complex geological systems. Full article

The isothermal oxidation behavior of single crystal DD6 film-cooling blades was investigated. The isothermal oxidation tests were conducted at 1050 °C, and the phase analysis was performed by XRD, while SEM (EDS) was employed to observe the material. In addition to experimental studies, a numerical simulation using three-dimensional finite element analysis based on Abaqus software (Version 6.13) was implemented to model the growth stress in specimens during the isothermal test. The obtained results showed that the average oxidation rate of specimens rose with increments in film hole spacing, up to a maximum value at a film hole spacing of 0.75 mm, and then fell, which could be interpreted with the concepts of the oxidation-affected zone and the growth stress. The results obtained from the numerical simulation of the growth stress agreed with the experimental results of the average oxidation rate. The oxide scale of film-cooling specimens mainly consisted of three layers, the NiO outer layer, the spinel sublayer containing cracks, and the non-continuous thin Al₂O₃ inner layer. The surface of the oxide scale commonly underwent spallation of the NiO outer layer, and the exposed sublayer could grow new NiO particles. The size of the NiO particles on the edge of the film holes was larger than those on the walls of the film holes. SEM images clearly showed that electro-hydraulic beam drilling on DD6 superalloy specimens could erode the γ phase in the γ/γ′ two-phase matrix, thereby inducing damages in regions near film holes. Full article

With the benefits of reduced travel time and alleviated traffic congestion, tunnel construction significantly enhances urban mobility. Meanwhile, tunnel construction accidents result in many casualties and property losses. To minimize accidents associated with tunnel construction while keeping its benefits, it is important to enhance the effectiveness and efficiency of training programs for construction workers. However, there is a lack of training evaluation systems specifically designed for tunnel construction workers, along with limited research on the effectiveness and efficiency of training programs for this group. This paper targets personnel from the China Railway 14th Bureau Group Company, aiming to evaluate a training program designed for tunnel construction workers. Three popular training approaches are proposed to evaluate the effectiveness and efficiency of training outcomes, including WeChat push safety construction knowledge (WP), the emergency drill (ED), and the unitive lecture (UL). Additionally, a concept of study is conducted to examine the performance of the proposed approaches in eighteen schemes that vary at different levels of training intensity by using VR (virtual reality), an electroencephalogram (EEG) system, and data enveloping analysis (DEA). The results show that the ED is the most effective training method, enabling industry professionals to respond effectively to unsafe situations by equipping them with critical skills through comprehensive training. Additionally, the ED has great potential for training tunnel construction workers via the provision of simulated experiences to enhance their safety preparedness. Full article

The double-connection structure of bionic joints of mining drill pipes has solved the problem of drill drop caused by fatigue cracks. However, with low-melting-point elastic–ductile alloy filling in the bionic joint, the thread on the joint cannot be hardened by high-temperature surface hardening treatments such as quenching and nitriding, making it prone to thread gluing or excessive wear. In this paper, the feasibility of diamond-like film deposition on the surface of a bionic drill pipe thread was studied. A tungsten transition film was used to improve the thickness of the film and the interfacial bond strength between the film and the substrate. The test results show that the total thickness of the DLC film is about 3~5 μm, the roughness is less than 2 μm, the hardness of the film reaches 24.4 GPa, the friction coefficient is 0.04, and the critical load is 56 N. SEM and EDS analyses show that the tungsten film and the bionic joint thread form a metallurgical structure. The morphology of the diamond-like carbon film is uniform and dense, and there is no obvious stratification between the substrate material. The joint with a diamond-like coating treatment has a longer service life than joints receiving conventional high-temperature nitriding treatment. Full article

In this work, a hydrometallurgical process for the recycling of diamond core drilling crowns by means of aqua regia leaching and subsequent alkali leaching was investigated. This investigation continues a previous study in which nitric acid was used for the acid leaching phase. In the current study, higher tungsten recovery was achieved, reaching 98.2%, which is an improvement of about 1.5%. Another advancement of this study was the high Co recovery (97.21%) and the high purity of the tungsten trioxide obtained, comparable to the previously proposed technological process. Furthermore, a novel laboratory method for testing recycled diamond drilling crowns based on infrared thermography was introduced. Although this innovative approach is not the most accurate, it is fast and cost-effective and provides valuable results before the actual field test is conducted as a final evaluation. In addition, the infrared thermography method offers the advantage of non-destructive testing, ensuring that the diamond drilling crowns can be assessed without compromising their structural integrity. Other instrumental methods used to characterize the products and intermediates were X-ray diffraction (XRD), scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS), and laser desorption ionization mass spectrometry (LDI-MS). The analytical method for the concentrations in all working solutions was ICP-AES. Full article

In the case of concrete built into a structure, the static secant modulus of elasticity (E_c,s) is often estimated based on its dynamic value (E_d) measured by the ultrasonic pulse velocity method instead of direct tests carried out on drilled cores. Meanwhile, the prevailing equations applied to estimate E_c,s often overlook the impact of concrete moisture. This study aimed to elucidate the moisture impact across two normal-weight structural concretes differing in compressive strength (51.6 and 71.4 MPa). The impact of moisture content was notably more evident only for the weaker concrete, according to dynamic modulus measurements. In other cases, contrary to the literature reports and expectations, this effect turned out to be insignificant. These observations may be explained by two factors: the relatively dense and homogeneous structure of tested concretes and reduced sensitivity of E_c,s measurements to concrete moisture condition compared to E_d measurements obtained using the ultrasonic method. Additionally, established formulas to estimate E_c,s were verified. The obtained modulus results tested under different moisture conditions of normal-weight concretes were also compared with those of lightweight aggregate concretes of identical volume compositions previously obtained in a separate study. Full article

The oil and gas industry faces significant challenges due to wear on drilling motor components, such as thrust pins and inserts. These components are critical to the efficiency and reliability of drilling operations, yet are susceptible to wear, leading to significant economic losses, operational downtime, and safety risks. Despite previous research on wear-resistant materials and surface treatments, gaps exist in understanding the unique properties of thrust pins and inserts. The aim of this study is to enhance mechanical system performance by characterizing the wear resistance of these components. Through chemical analysis, hardness assessments, and metallographic examinations, the study seeks to identify specific alloys and microstructures conducive to wear resistance. Key findings reveal that AISI 9314 thrust pins exhibit superior wear resistance with a tempered martensite microstructure and a hardness of 41 HRc, whereas AISI 9310 inserts are less resistant, with a hardness of 35 HRc. The research employs advanced techniques, including a pin-on-disc tribometer, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and profilometry, to evaluate wear behavior, visualize wear patterns, analyze elemental composition, and quantify material loss and surface roughness. Our findings demonstrate that optimizing the material selection can significantly enhance the durability and efficiency of drilling motors. This has profound implications for the oil and gas industry, offering pathways to reduce maintenance costs, improve operational efficiency, and contribute to environmental sustainability by optimizing energy consumption and minimizing the carbon footprint of drilling operations. Full article

This study documents the geochemical and mineralogical characteristics of three nickel reference materials for the battery minerals industry: ¼ drill cores of typical nickel-rich ores, centimeter-sized chips of run-of-mine ore, and finely ground nickel concentrate, all from the same deposit. A novel aspect of this study is that we have used both traditional geoanalytical techniques for battery mineral characterization (whole-rock geochemistry, QXRD, SEM-EDS, EPMA, and automated mineralogy), as well as emerging and novel technologies (scanning micro-XRF, LIBS, FTIR, and Raman). This multidisciplinary method provides cross-verified characterization data that can be used for building mineral identification libraries and highlights the optimized combination for the analysis of these matrix types. Full article

The electro-discharge (ED) drilling of precision boreholes in difficult-to-machine materials, particularly with respect to the cost-effectiveness of the overall process, is still a challenge. Flushing is one key factor for the precise machining of boreholes, especially with high aspect ratios. Therefore, the influence of internal and external flushing geometries for six types of brass tool electrodes with a diameter of 3 mm with and without a helical groove was analyzed experimentally and numerically. Using this helical external flushing channel, drilling experiments in X170CrVMo18-3-1 (Elmax Superclean) with an aspect ratio of five revealed a material removal rate (MRR) that was increased by 112% compared with a rod electrode, increased by 28% for a single-channel tool electrode and decreased by 8% for a multi-channel tool electrode. Signal analyses complemented these findings and highlighted correlations between classified discharge event types and the experimental target parameters. Amongst others, it was verified that the arcing frequency ratio drove the electrode wear rate and the beneficial frequency ratio correlated with the MRR and the surface roughness Ra. Sophisticated 3D computational fluid dynamics (CFD) models of the liquid phase were introduced and evaluated in great detail to demonstrate the validity and further elucidate the effect of the external flushing channel on the evacuation capability of debris and gas bubbles. The presented methods and models were found to be suitable for obtaining in-depth knowledge about the flushing conditions in the ED drilling working gap. Full article

To elucidate the reservoir characteristics of organic-rich siliceous shale of the Upper Permian Dalong Formation in western Hubei, this study focused on the drilling cores of Well ED-2. Various techniques, including a mineral composition analysis, an organic carbon content analysis, a vitrinite reflectance measurement, a total porosity determination, field emission scanning electron microscopy (FE-SEM), and low-pressure CO₂ and N₂ physical adsorption tests, were employed to analyze the mineralogy, organic geochemistry, total porosity, and pore structure characteristics. Additionally, the factors influencing the reservoir performance of the Dalong Formation shale were investigated. The results indicated that the Dalong Formation’s shale was characterized as an organic-rich siliceous shale. Organic matter was mainly of sapropelic type, with a relatively high thermal evolution degree and Ro ranging from 2.59% to 2.76%. The total porosity of the Dalong Formation’s siliceous shale was low, indicating poor reservoir properties. Organic matter pores were highly developed, mainly the ones formed after the hydrocarbon generation of solid asphalt. Micropores and mesopores were the dominant pore types in the shale, with macropores being significantly less abundant. The study further revealed that the pore volume and specific surface area exhibited a significantly positive correlation with total organic carbon (TOC) content and clay minerals, while demonstrating a weak negative correlation with quartz content. The comprehensive analysis revealed that there were two factors contributing to the poor physical properties of organic-rich siliceous shale in the Dalong Formation. Firstly, in siliceous shale with a high quartz content, the siliceous component was partly derived from the siliceous cementation of hydrothermal fluids. This process led to the formation of secondary quartz that filled intergranular pores, resulting in a decrease in macropore volume, total porosity, and a weak negative correlation with quartz content. Secondly, in siliceous shale with a relatively high clay mineral content, the organic matter was subjected to stronger compaction due to the relatively low content of brittle minerals. This compaction caused the destruction of most macropores, leaving behind primarily micropores and mesopores. Consequently, the average pore size decreased, leading to poor physical properties. Full article

Mitigation of greenhouse gas emissions is becoming a significant factor in all industries. Cement manufacturing is one of the industries responsible for greenhouse gas emissions, specifically carbon dioxide emissions. Pozzolanic materials have long been used as cement additives due to the pozzolanic reaction that occurs when hydrated and the formation a cementitious material similar to that of cement. In this study, shale, which is a common component found in wellbore drill cuttings, was used in various sizes and quantities to determine the effect it had on the mechanical properties of wellbore cement. The unconfined compressive strength of the cement containing shale was compared to the cement without shale to observe the effect that both the quantity and particle size had on this property. SEM–EDS microscopy was also performed to understand any notable variations in the cement microstructure or composition. The samples containing micron shale appeared to have the best results of all the samples containing shale, and some of the samples had a higher UCS than one or more of the base case samples. Utilization of cuttings as a cement additive is not just beneficial in that it minimizes the need for cuttings removal and recycling, but also in that it reduces the amount of greenhouse gas emissions associated with cement manufacturing. Full article

The Marcellus shale is an unconventional reservoir of significant economic potential with Total Organic Carbon (TOC) ranging from 1 to 20%. Hydraulic fracturing is used to extract the shale’s resources, which requires large amounts of water and can result in mineral-rich flowback waters containing hazardous contaminants. This study focuses on a geochemical analysis of the flowback waters and an evaluation of the potential environmental impacts on water and soil quality. Drilled core samples from different depths were treated with lab-prepared hydraulic fracturing fluids. Rock samples were analyzed using Energy Dispersive Spectroscopy (EDS), while effluents’ chemical compositions were obtained using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). A comparison of results from drilled core samples treated with additives for hydraulic fracturing to those treated with deionized (DI) water confirms that, as expected, the major elements present in the effluent were Ca, Ba, and Cl in concentrations greater than 100 µg/L. The most concerning elements in the effluent samples include As, Ca, Cd, Pb, Se, S, K, Na, B, Mo, and Mn, with Cd and Cr values averaging 380 and 320 µg/L, respectively, which are above safe limits. Se concentrations and high levels of Ca pose major safety and scaling concerns, respectively. We also compared Marcellus shale drilled core samples’ geochemical reactivity to samples collected from an outcrop. Full article

The rate of penetration (ROP) is an important indicator affecting the drilling cost and drilling performance. Accurate prediction of the ROP has important guiding significance for increasing the drilling speed and reducing costs. Recently, numerous studies have shown that machine learning techniques are an effective means to accurately predict the ROP. However, in petroleum engineering applications, its robustness and generalization cannot be guaranteed. The traditional empirical model has good robustness and generalization ability. Based on the quantification of data similarity, this paper establishes a hybrid model combining a machine learning method and an empirical method, which combines the high prediction accuracy of the machine learning method with the good robustness and generalization of the empirical method, overcoming the shortcomings of any single model. The AE-ED (the Euclidean Distance between the input data and reconstructed data from the autoencoder model) is defined to measure the data similarity, and according to the data similarity of each new piece of input data, the hybrid model chooses the corresponding single model to calculate. The results show that the hybrid model is better than any single model, and all the evaluation indicators perform better, making it more suitable for the ROP prediction in this field. Full article

Molecular traps, based on natural zeolites, are being used to remove harmful gaseous substances (VOCs). These chemical devices must be supported on an adequate substrate (e.g., paper, polymeric films, etc.). To achieve very strong adhesion with the substrate, the planar shape is the most convenient choice for these systems. Clinoptilolite is a nanostructured material made of nanosized lamellae with a thickness of 40 nm. A new technological approach, based on the use of an abrasive drill, was selected to exfoliate a natural clinoptilolite sample, thus leading to a powder made of single lamellar crystals. The obtained lamellae have been characterized by TEM, SEM/EDS, and XPS. Full article

AlCrN coatings, which are characterized by high hardness and good wear resistance, are often used for drilling, milling, and punching tools. Therefore, the study of the behaviour of these coatings under cyclic impact loading is essential for their optimization. Our previous work has focused on the study of the composition and microstructure of AlCrN coatings prepared using a cathodic arc deposition system with a SCIL^® controller that controls the average ion energy per deposited atom (E_d). Two sets of coatings were prepared in two different modes, with a metal target and with a poisoned target. The chemical compositions of the coatings were very similar regardless of their deposition conditions, but the structure and mechanical properties of the coatings depended strongly on E_d. The present work focused on the scratch adhesion and impact wear of these two sets of AlCrN coatings. The lifetimes of both sets of samples under repeated dynamic impacts were tested using a dynamic impact tester with a WC-Co ball. It was shown that the impact behaviour of the coatings prepared in the metallic regime does not depend on the deposition conditions. However, the impact behaviour of the coatings deposited in poisoned mode was improved by increasing E_d. Full article