Search Results (427)

Deep drilling and horizontal wells, as important means of unconventional oil and gas development, face problems with the high energy consumption but low removal efficiency of traditional well washing equipment, the uneven cleaning of horizontal well intervals, and an insufficient degree of automation. This paper proposes a novel hydraulic drive well washing device which consists of two main units. The wellbore cleaning unit comprises a hydraulic drive cutting–flushing module, a well cleaning mode-switching module, and a filter storage module. The unit uses hydraulic and mechanical forces to perform combined cleaning to prevent mud and sand from settling. By controlling the flow direction of the well washing fluid, it can directly switch between normal and reverse washing modes in the downhole area, and at the same time, it can control the working state of corresponding modules. The assembly control unit includes the chain lifting module and the arm assembly module, which can lift and move the device through the chain structure, allow for the rapid assembly of equipment through the use of a mechanical arm, and protect the reliability of equipment through the use of a centering structure. The device converts some of the hydraulic power into mechanical force, effectively improving cleaning and plugging removal efficiency, prolonging the downhole continuous working time of equipment, reducing manual operation requirements, and comprehensively improving cleaning efficiency and energy utilization efficiency. Full article

Sensorineural hearing loss occurs when cochlear hair cells fail to convert mechanical sound waves into electrical signals transmitted via the auditory nerve. Cochlear implants (CIs) restore hearing by directly stimulating the auditory nerve with electrical impulses, often while preserving residual hearing. Over the past two decades, robotic-assisted techniques in otologic surgery have gained prominence for improving precision and safety. Robotic systems support critical procedures such as mastoidectomy, cochleostomy drilling, and electrode array (EA) insertion. These technologies aim to minimize trauma and enhance hearing preservation. Despite the outpatient nature of most CI surgeries, surgeons still face challenges, including anatomical complexity, imaging demands, and rising costs. Robotic systems help address these issues by streamlining workflows, reducing variability, and improving electrode placement accuracy. This review evaluates robotic systems developed for cochlear implantation, focusing on their design, surgical integration, and clinical outcomes. This review concludes that robotic systems offer low insertion speed, which leads to reduced insertion forces and lower intracochlear pressure. However, their impact on trauma, long-term hearing preservation, and speech outcome remains uncertain. Further research is needed to assess clinical durability, cost-effectiveness, and patient-reported outcomes. Full article

Drilling oil and gas wells is a complex process that requires a combination of several parameters to dig into the ground. Inappropriate drilling parameter settings and reaction forces can lead to unwanted vibrations, which can negatively impact the drill string and cause damage to drill bits. To reduce unwanted oscillations, drilling vibration modeling is the first approach used to determine the behavior of the drill string under various conditions. Natural frequencies, one of the modal characteristics of a vibrating drill string, can be estimated by analytical or numerical models. However, as the field conditions become more complicated, analytical models become increasingly difficult to use, and alternative approaches must be adopted. The main objective of this paper is to investigate the natural frequencies of drill strings with real geometry under coupled vibration modes using both analytical and finite element methods. This study bridges the literature gap in modeling stepped drill string geometries, which are usually represented as uniform beams. This paper used analytical and finite element models to determine the drill string’s lateral, axial, and torsional natural frequencies under varying lengths of drill pipes and drill collars. To assess the reliability of finite element models under complex geometry, the drill string was approximated as a stepped beam rather than a uniform beam. Then, a comparison was made with analytical models. The results showed that the length of drill pipes has a pronounced effect on the natural frequencies of the overall drill string for the three vibrational modes, while drill collar length only has a notable impact on the torsional mode. These findings contribute to drilling systems’ reliability and efficiency in the oil and gas energy sector. Full article

The shallow, soft subsea formations, characterized by low strength and poor stability, lead to complex interactions between the screw motor drilling tool and the wellbore wall during directional drilling, complicating the accurate evaluation of the tool’s deflection capability. To address this issue, this paper proposes an integrated mechanical analysis method combining three-dimensional finite element analysis and transient dynamic analysis. By establishing a finite element model using 12-DOF (degree-of-freedom) spatial rigid-frame Euler–Bernoulli beam elements, coupled with well trajectory coordinate transformation and Rayleigh damping matrix, a precise description of drill string dynamic behavior is achieved. Furthermore, the introduction of pipe–soil dynamics and the p-y curve method improves the calculation of contact reaction forces between drilling tools and formation. Case studies demonstrate that increasing the tool face rotation angle intensifies lateral forces at the bit and stabilizer, with the predicted maximum dogleg severity within the first 10 m ahead of the bit progressively increasing. When the tool face rotation angle exceeds 2.5°, the maximum dogleg severity reaches 17.938°/30 m. With a gradual increase in the drilling pressure, the maximum bending stress on the drilling tool, maximum lateral cutting force, and stabilizer lateral forces progressively decrease, while vertical cutting forces and bit lateral forces gradually increase. However, the predicted maximum dogleg severity increases within the first 10 m ahead of the bit remain relatively moderate, suggesting the necessity for the multi-objective optimization of drilling pressure and related parameters prior to actual operations. Full article

Hydraulic oscillators can effectively reduce the frictional resistance of the horizontal well drilling column and increase mechanical drilling speed, but the influence of geological and operational conditions on the drag reduction performance of these tools has not been fully studied, resulting in the selection of hydraulic oscillators still relying mainly on field experience. This study investigates the effects of drill string material, drilling fluid, and tool type on the drag reduction capability of tools. Friction coefficients of two commonly used drill string materials (G105 steel, S135 steel) with three common formation types (sandstone, shale, and limestone) were measured under oil-based and water-based drilling fluid infiltration conditions at different speeds of movement. The experimentally obtained friction coefficients were incorporated into a nonlinear mechanical model of the drill string equipped with a hydraulic oscillator, which was solved using the finite difference method. The results showed that the drill string materials had a limited effect on tool drag reduction capabilities, while rock type and drilling fluid type had a more significant impact. The drag reduction effect of tools in oil-based drilling fluids was better than that of water-based drilling fluids. In shale, the drag reduction effect of tools was better than that in sandstone and limestone. Increasing the amplitude enhanced the drag reduction ability of tools more than increasing the vibration frequency. Increasing the amplitude and frequency of the tool in an oil-based drilling fluid environment produced a more significant increase in drag reduction than doing the same in a water-based drilling fluid environment. These findings can provide theoretical guidance for the design of output characteristics of hydraulic vibrators and field selection of tools under different drilling conditions. Full article

The drilling machinability of glass fiber G₁₄, basalt fiber B₁₄, and two hybrid laminates (B₄G₆B₄, G₄B₆G₄) was evaluated through 36 full-factorial experiments employing an HSS-G drill, three spindle speeds (715, 1520, 3030 rpm), and three feed rates (0.1–0.3 mm rev⁻¹). Peak thrust force varied from 65.8 N for B14 at 0.1 mm rev⁻¹ to 174.3 N for G₁₄ at 0.3 mm rev⁻¹; hybrids occupied the intermediate range of 101–163 N. Infra-red thermography recorded maximum drill temperatures of 110–120 °C for G₁₄, almost double those of B₁₄, while both hybrids attenuated hotspots to below 90 °C. ANOVA attributed 73.4% of thrust force variance to feed rate, with material type and spindle speed contributing 15.5% and 1.7%, respectively; for temperature, material type governed 41.5% of variability versus 17.0% for speed. Dimensional quality tests revealed that the symmetric hybrid G₄B₆G₄ maintained entrance and exit diameters within ±2% of the nominal 6 mm, whereas B₄G₆B₄ over-expansion exceeded 8% at the lowest feed and G₁₄ exit diameters grew to 6.1 mm at 0.3 mm rev⁻¹. Integrating basalt compliance with glass stiffness, therefore, halves thrust force relative to G₁₄, suppresses delamination and overheating, and offers a practical strategy to prolong tool life and improve hole quality in multi-material composite structures. These insights guide parameter selection for lightweight hybrid composites in aerospace, renewable-energy installations, and marine components worldwide. Full article

The aim of this study is to develop a simple and reliable laboratory testing procedure for evaluating the bond strength of cement–formation sheaths that considers cement slurry composition and contamination as well as formation strength and formation surface conditions (roughness and contamination). Additionally, a simple and practical empirical correlation is developed for predicting cement–rock bond strength based on the routine mechanical properties of hard-set cement and formation rock. Cement slurries composed of Yamama cement type 1 and 25% local Saudi sand, in addition to 40% fresh water, are used for all investigations in this study. Oil well cementing is a crucial and essential operation in the drilling and completion of oil and gas wells. Cement is used to protect casing strings, isolate zones for production purposes, and address various hole problems. To effectively perform the cementing process, the cement slurry must be carefully engineered to meet the specific requirements of the reservoir conditions. In oil well cementing, the cement sheath is a crucial component of the wellbore system, responsible for maintaining structural integrity and preventing leakage. Shear bond strength refers to the force required to initiate the movement of cement from the rock formation or movement of the steel casing pipe from the cement sheath. Cement–formation sheath bond strength is a critical issue in the field of petroleum engineering and well cementing. Cement plays a crucial role in sealing the annulus (the space between the casing and the formation) and ensuring the structural integrity of the well. The bond strength between the cement and the surrounding geological formation is key to preventing issues such as fluid migration, gas leaks, and wellbore instability. To achieve the study objectives, sandstone and sandstone–cement composite samples are tested using conventional standard mechanical tests, and the results are used to predict cement–formation sheath bond strength. The utilized tests include uniaxial compression, direct tensile, and indirect tensile (Brazilian) tests. The predicted cement–rock sheath bond strength is compared to the conventional laboratory direct cement–formation sheath strength test outcomes. The results obtained from this study show that the modified uniaxial compression test, when used to evaluate cement–formation shear bond strength using cement–rock composite samples, provides reliable predictions for cement–formation sheath bond strength with an average error of less than 5%. Therefore, modified uniaxial compression testing using cement–rock composite samples can be standardized as a practical laboratory method for evaluating cement–formation sheath bond strength. Alternatively, for a simpler and more reliable prediction of cement–formation sheath bond strength (with an average error of less than 5%), the empirical correlation developed in this study using the standard compressive strength value of hard-set cement and the standard compressive strength value of the formation rock can be employed separately. For the standardization of this methodology, more generalized research should be conducted using other types of oil well cement and formation rocks. Full article

Carbon fiber reinforced polymers (CFRPs) are significantly vital for industries. However, the drilling process of a CFRP is considered a challenge due to its nature, which causes delamination, fiber pull-out, peel-up, high friction, and a decrease in cutting tool life. Wet drilling is necessary for minimizing defects, and lubricants are very costly. In the current work, ultrasonic-assisted drilling (UAD) with a longitudinal vibration of 39.7 kHz was applied to the drill bit in the feed direction, used for CFRPs, and compared with conventional drilling (CD). Low spindle speeds under 5000 rpm were applied with different feed rates. The morphology, delamination factor, and cutting forces were investigated through the specific input machining parameters for CD and UAD. SEM was applied to study the morphology of the hole entrance and exit as well as the burr heights of evacuated chips. UAD with 39.7 kHz succeeded in minimizing the surface roughness by 50% compared with the surface roughness resulting from CD and could drill high-precision holes for CFRPs with a trade-off concept, besides achieving near-zero delamination (K ≃ 1) in the absence of a lubricant, which is being extended for industrial application. Full article

During the drilling process of high-temperature geothermal wells, the high temperature at the bottom of the well and the complex lithology of the formation lead to poor tooth loss prevention in cone drill bits. This issue seriously affects the life and efficiency of geothermal drilling. The stability of the wellbore is one of the key issues in the drilling process of high-temperature geothermal wells, and the fixed-tooth strength of the roller drill bit directly affects the stability of the wellbore and drilling efficiency. The heat transfer effect of the wellbore will exacerbate the thermal expansion and performance degradation of the drill bit material in high-temperature environments, leading to a decrease in the strength of the fixed teeth. To address this, this study used a high-temperature experimental apparatus to systematically test the fixed-tooth strength of roller drill bits. By using five types of tooth spacing: 4, 6, 8, 10, and 12 mm, three types of tooth diameters: 12, 14, and 16 mm, and three types of interference fit: 0.075, 0.095, and 0.115 mm, the maximum fastening force of fixed teeth was measured under different conditions, and its variation pattern was analyzed. The experimental results show that the higher the temperature, the weaker the tooth-fixing strength. Under the same perforation distance, the maximum fastening force decreases with increasing temperature. Compared with normal temperature, the maximum fastening force decreases by about 49.6–64.5%. At the same temperature, the maximum fastening force is the largest when the perforation distance is 10 mm. When the temperature increases, the maximum fastening force increases with the tooth diameter; that is, the larger the tooth diameter, the better the tooth-fixing effect. At the same temperature, the maximum fastening force first increases and then decreases with increasing interference. The maximum fastening force is the largest when the interference is 0.095 mm. At 120 °C, 180 °C, and 240 °C, the maximum fastening force is reduced by 21.9%, 29.4%, and 56.6%, respectively, compared to normal temperature. The study reveals the variation law of tooth-fixing strength under high-temperature conditions and proposes tooth-fixing methods and suggestions suitable for high-temperature geothermal wells. This provides a scientific basis for solving the problem of tooth loss of roller bits in high-temperature geothermal drilling and has important theoretical and practical application value. Full article

In recent years, polycrystalline diamond compact (PDC) drill bits have seen significant advancements. They have replaced over 90% of the workload traditionally handled by roller cone bits and have become the predominant choice in energy drilling due to their superior efficiency and durability. However, PDC drill bits are susceptible to adhesion of rock cuttings during drilling in muddy formations, leading to mud accumulation on the bit surface. This phenomenon can cause drill bit failure and may contribute to downhole complications, including tool failure and borehole instability. The adhesion issue between PDC drill bits and mud rock cuttings underground is primarily influenced by the normal adhesion force between the drill bit surface and the mud rock cuttings. Therefore, biological non-smooth surface technology is applied to the prevention and control of drill bit balling. It is an optimal selection of biomimetic non-smooth surface structures with reduced adhesion and detachment properties. A non-smooth surface model for the PDC drill bit body is established through the analysis of the morphological characteristics of natural biological non-smooth surfaces. An experimental platform is designed and manufactured to evaluate the adhesion performance of non-smooth surface specimens. Indoor experiments are conducted to test the normal adhesion force of non-smooth surface specimens under varying morphologies, sizes, and contact times with clay. Finally, the anti-adhesion performance of the non-smooth surface unit structures is then analyzed. The normal adhesion force with a contact time of 12 h is as follows: 340 Pa of big square raised, 250 Pa of middle square raised, 190 Pa of small square raised, 315 Pa of big circular groove, 280 Pa of middle circular groove, 200 Pa of small circular groove, 225 Pa of big dot pit, 205 Pa of middle dot pit, and 130 Pa of small dot pit. Compared with the normal adhesion force of 550 Pa for smooth surface specimens with a contact time of 12 h, the anti-adhesion properties of the three non-smooth surface unit structure specimens designed in this paper were verified. We analyzed the anti-adhesion performance of non-smooth surface unit structures. At the critical contact time when the adhesion force tends to stabilize, the adhesion forces of different specimens are as follows: 330 Pa of big square raised, 237.5 Pa of middle square raised, 175 Pa of small square raised, 290 Pa of big circular groove, 250 Pa of middle circular groove, 160 Pa of small circular groove, 210 Pa of big dot pit, 185 Pa of middle dot pit, and 115 Pa of small dot pit. The results indicate that the anti-adhesion effect of small dot pit structures is the most effective, while the anti-adhesion effect of large square convex structures is the least effective. As the size of the unit structure decreases, it becomes more similar to the surface size of the organism. Additionally, a shorter contact time with clay leads to a better anti-adhesion effect. These findings provide new insights and research directions for the effective prevention and control of mud wrapping on PDC drill bits. Full article

We systematically investigated the anchorage performance of self-drilling anchor bolts in strongly weathered dolomite through integrated field pull-out tests and FLAC3D numerical modeling. The study incorporates symmetry principles in both experimental design and numerical simulations to ensure balanced force distribution and model simplification. Experimental data collected from a slope reinforcement project demonstrated that grouting parameters of 0.8 MPa pressure and 0.8 water–cement ratio achieved an interfacial bond strength of 0.147 MPa, surpassing the recommended value by 22.5%. A modified FLAC3D pile element, calibrated against RS6-01 anchor bolt test data, exhibited improved alignment with load–displacement curves, converging to 272 kN ultimate capacity at 26.1 mm displacement. Symmetrical anchor configurations in the numerical model reduced computational complexity while maintaining accuracy in stress distribution analysis. Through orthogonal experimental design, symmetry-driven parameter optimization identified a 7 m bolt length, 30° installation angle, and 2 m spacing as the most effective configuration. This solution increased the slope safety factor by 19.98% while reducing displacements by 46–62%. The symmetry in anchor spacing and angular alignment contributed to uniform stress redistribution, enhancing slope stability. The findings highlight the synergy between symmetry principles and geotechnical reinforcement strategies. Full article

This paper explores a novel double-flush riveting process for assembling hybrid busbars made from aluminum and copper sheets. The process involves drilling and forging countersunk holes with controlled geometry in both materials followed by compression of cylindrical rivets into the holes to create strong, form- and force-closed mechanical joints. Experimental and numerical analyses are combined to examine material flow, quantify the required forces, and assess the structural integrity of the joints through destructive testing. Additionally, the electrical resistance of these novel joints is evaluated and compared with that of ideal and conventional fastened hybrid busbar joints in order to assess their performance and reliability in real-world electrical service conditions. The results indicate that the novel double-flush riveting process is a viable alternative to other conventional joining processes, such as fastening, delivering good structural integrity and enhanced electrical conductivity for hybrid busbar applications. Full article

Automation has transformed process optimization across industries by enhancing efficiency, safety, and reliability while minimizing human intervention. This paper presents a model-based optimization strategy tailored for automated drilling operations, focusing on maximizing performance while maintaining operational safety. The approach employs real-time control of key parameters, such as applied force and rotational speed, through a robust closed-loop control system. An adaptive detection algorithm is incorporated to dynamically adjust operational parameters when encountering changing conditions. This real-time adaptability ensures efficient performance under diverse scenarios while mitigating risks. In the simulation, the data used for modeling drillstring dynamics are sourced from a publicly available benchmarking dataset, which provides a reliable basis for evaluation. From the simulation results, it is clear that the drilling optimization framework is capable of achieving high performance with lower energy consumption while maintaining effective vibration mitigation and prevention. This balance is essential for ensuring operational efficiency and tool longevity in dynamic environments. The findings highlight the potential of this framework to enhance automated systems in energy, construction, and other sectors requiring precise control of dynamic mechanical processes. Full article

This study develops a quantitative framework to assess performance degradation and damage evolution in CRTS I ballastless track slabs. Based on the impact-echo method, the internal void distribution characteristics of the new and old track slabs were obtained. The track slabs were sampled separately by drilling cores to verify the distribution of voids, and uniaxial compression tests were conducted simultaneously to quantify the attenuation of bearing capacity. The on-site wheel–rail force and temperature field data were monitored, based on the established three-dimensional finite element model of CRTS I ballastless track, and the damage distribution characteristics of the track slab under different load combinations after performance degradation were studied. The results show the following: (1) As the performance of the track slabs gradually deteriorated, it was reflected in the increasing internal void distribution area from 0.5% to 3.6%, corresponding to a 22.4% decrease in core strength. (2) The on-site monitoring results showed that the average wheel–rail force was 84.5 kN. The temperature gradient range varied from −50.4 °C/m to 100.0 °C/m, exceeding the allowable value of the design specifications. (3) The actual damage distribution of the track slab after performance degradation under different load combinations significantly increased at key stress locations such as near fasteners, convex abutments, and anchor holes of prestressed steel bars, which required special attention in actual maintenance and repair. Full article

This study explores advanced process monitoring for one-shot drilling of aeronautical stacks made of aluminium 2024 and carbon fibre-reinforced polymer (CFRP) laminates using a 4.8 mm diameter drilling tool and unsupervised machine learning techniques. An experimental campaign is conducted to collect thrust force and torque signals at a 10 kHz sampling rate during the drilling process. These signals are employed for real-time process monitoring, focusing on material change detection and anomaly identification, where anomalies are defined as holes that fail to meet predefined quality criteria. An innovative approach based on unsupervised learning is proposed to enable automatic material change identification, signal segmentation, feature extraction, and hole quality assessment. Specifically, a semi-supervised approach based on a Gaussian Mixture Model (GMM) and 1D Convolutional AutoEncoder (1D-CAE) is employed to detect deviations from normal drilling conditions. The proposed method is benchmarked against state-of-the-art supervised techniques, including logistic regression (LR) and Support Vector Machines (SVMs). Results show that these traditional models struggle with class imbalance, leading to overfitting and limited generalisation, as reflected by the F1 scores of 0.78 and 0.75 for LR and SVM, respectively. In contrast, the proposed semi-supervised approach improves anomaly detection, achieving an F1 score of 0.87 by more effectively identifying poor-quality holes. This study demonstrates the potential of deep learning-based semi-supervised methods for intelligent process monitoring, enabling adaptive control in the drilling process of hybrid stacks and detecting anomalous holes. While the proposed approach effectively handles small and imbalanced datasets, further research into the application of generative AI could enhance performance, aiming for F1 scores above 0.90, thereby supporting adaptation in real industrial environments with high performance. Full article