To address the challenges of rapid bit failure and high drilling costs associated with hard limestone in Sichuan Basin of China, we conducted rock-breaking experiments and simulations of shaped (cylindrical, ridge, and chopper) cutters. Rock mechanics, drillability, and acoustic emission indentation tests revealed the drilling resistance characteristics of the limestone: average uniaxial compressive strength of 202.472 MPa, tensile strength of 7.092 MPa, and drillability of 7.866. We evaluated the performance differences between the shaped cutters before introducing an efficient and innovative finite-discrete-infinite element method (FDIEM) to establish an interaction model between the shaped cutters and limestone. The simulation results indicated the following: (1) The shaped cutters demonstrated superior rock-breaking performance compared to the traditional cylindrical cutter. (2) Compared with the cylindrical cutter, the ridge cutter yielded the lowest peak indentation force and mechanical specific energy, with reductions of 8.71 % and 33.83 %, respectively. This confirmed that the ridge cutter had the optimal tooth profile for the target formation. Its rock-breaking mechanism relied on the convex edges to induce localized high stress in the rock, which enabled efficient rock fragmentation via a plowing mode while mitigating frictional resistance from cuttings. (3) The novel chopper cutter with its secondary step surface exerted a buffering effect on the cuttings, thereby achieving high cutting stability. This study provides theoretical and technical support for the design of personalized drill bits and the acceleration of the rate of penetration (ROP) in deep hard rock formations.

Artificial intelligence (AI) is profoundly reshaping the technological framework of industrial robotics, driving its transition from pre-programmed automation to autonomous, adaptive agents. This paper systematically reviews the key advancements of AI across three core dimensions of intelligence: perception, decision-making, and execution. Analysis indicates that AI is propelling industrial robots from tools executing predefined tasks towards intelligent partners capable of adapting to unstructured environments, autonomously planning amid dynamic changes, and engaging in nuanced interactions with the physical world. This evolution reveals a shift from optimizing specific skills towards developing challenges persist for industrial-scale deployment, including model generalization capabilities, long-term robustness, and human-machine trust. Collectively, these advancements are shaping a new generation of intelligent industrial robotic systems that are more adaptable and capable of deeper collaboration with humans.

Based on China's marine geothermal resource endowment,this study evaluates the development potentials of shallow,medium-to-deep,and high-temperature hydrothermal resources,with a focus on key technological systems,development bottlenecks,and economic constraints.On this basis,a region-specific and phased development pathway is proposed:priority demonstration of high-temperature hydrothermal utilization in the deep water of the South China Sea,cascading use of medium-and low-temperature resources in the eastern coastal zone,and forward-looking research on enhanced geothermal systems and possible mineral-geothermal coupling in far-offshore areas.The study further proposes a distinctive marine"geothermal-plus"multi-energy synergistic development model,involving retrofitting of offshore oil and gas wells,wind-solar-geothermal hybrid systems,heat-electricity-water cogeneration,and heat-electricity-mineral coupling under suitable high-mineralization conditions.A strategic support framework is also outlined,covering technological innovation,equipment capability enhancement,policy incentives,industrial coordination,and ecological risk control.The study aims to provide a more prudent and operational scientific basis and technological support for advancing China's marine geothermal sector from resource assessment to demonstration-scale deployment.

Sand screenout is a major challenge in hydraulic fracturing, leading to the blockage of artificial fractures and negatively impacting efficiency and production. To improve early detection accuracy, this paper presents a hybrid neural network model for sand screenout prediction. The model integrates convolutional neural networks (CNN), bidirectional long short-term memory (BiLSTM), and an attention mechanism (Attention) to extract spatio-temporal features from fracturing parameters. Its hyperparameters are optimized using the crested porcupine optimizer (CPO). Furthermore, an enhanced pressure–time double-logarithmic model, incorporating thresholds and inflection points, is used to calculate the slope and improve warning accuracy. Experimental results demonstrate that the proposed model outperforms four comparison models in predicting fracturing pressure, achieving lower mean absolute error (MAE) and root mean squared error (RMSE), and a coefficient of determination (R2) near 0.98. Field tests show the model provides warnings 76 s earlier than manual operations across six fracturing stages in a Sichuan Basin shale gas field. Performance evaluation shows a precision of 84.6

15CrNiMo is an essential bearing steel in the mining equipment industry. Multi-body friction significantly contributes to the premature damage of bearings made from 15CrNiMo. This paper investigates the impact of laser shock peening (LSP) on the wear behavior of a carburized layer in 15CrNiMo under multi-body friction. Analysis using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) reveals that LSP induces high-density dislocations and twins in the near-surface layer of the carburized material. Following LSP treatment, the near-surface layer (up to 200 mu m) exhibits a 26 % increase in grain quantity, a 14.3 % reduction in average grain size, and a 5.3 % increase in the proportion of large-angle grain boundaries. Additional characterization of residual stress and microhardness indicates that LSP increases surface microhardness by 20.5 % and average hardness within the 850 mu m range by 18.8 % while creating a residual stress layer approximately 1 mm thick near the surface. Scanning electron microscopy (SEM), results indicate that untreated specimens primarily experience abrasive wear, characterized by ploughing grooves and pits. In contrast, after LSP, abrasive wear decreases, and wear resistance improves, with the dominant wear mechanism shifting to adhesion among multi-body friction materials. The primary anti-wear mechanism is attributed to the nano-crystalline layer and residual stress layer induced by LSP, which effectively suppresses surface ploughing by multi-body friction materials, reduces cutting and compressive stresses during friction, and inhibits the crack formation and propagation.

Coiled tubing (CT) is extensively employed in well drilling and completion operations, yet the issue of CT buckling occurs as the horizontal section extends. Deploying a tractor can effectively address the limitations of CT extension in horizontal sections. In this paper, a novel full hydraulic tractor with large traction force was proposed. The simulation models of the working cylinders under full hydraulic control were established, and the motion characteristics of the supporting cylinder and the traction cylinder of the full hydraulic tractor were obtained. A hydraulic integrated control valve (ICV) combining a sequence valve and a hydraulic check valve with a pilot hydraulic directional valve was proposed, which can realize the automatic reversing mechanism of the tractor. The full hydraulic automatic reversing mechanism and ICV-tractor joint simulation model were established. The simulation results showed that the full hydraulic reversing mechanism could realize the reciprocating motion of the piston of the traction cylinder, and the valve spool could maintain the maximum opening in two positions. In addition, the prototype was developed and the function verification experiment and traction experiment were carried out. The results showed that under full hydraulic control, two cylinders could move steadily in a certain order and cycle. The maximum traction force of the CT tractor for pulling coiled tubing in the casing reached 81.36 kN. This proved the correctness of the full hydraulic tractor with large traction force. This research provides equipment support for CT operations in ultra-long horizontal wells and makes a significant contribution to the lateral extension of horizontal wells.

Sand screenout is a critical challenge in hydraulic fracturing, affecting both the construction process and operational safety. This paper proposes a sand screenout warning model that integrates a combinatorial neural network and physical approaches to enhance both the speed and accuracy of sand screenout warnings. Firstly, the combined neural network uses a Transformer to capture key features during fracturing construction from historical data, and the extracted features are input to the Gated Recurrent Unit (GRU) for temporal prediction and the Crested Porcupine Optimizer (CPO) to further optimise the GRU-Transformer hyperparameters of the model. Additionally, the physical model improves the conventional inverse slope method by incorporating a threshold and sliding module, which enhances slope calculation and warning accuracy. The results showed that for fracturing pressure prediction, the proposed CPO-GRU-Transformer model obtained an RMSE value of 0.842 MPa, MAE of 0.613 Mpa, and R2 of 0.971, a smaller RMSE and MAE and a larger R2 than the three pressure prediction models, namely LSTM, GRU, and CPO-GRU. The proposed sand screenout warning model has been applied in the field construction of the U shale gas area in the Sichuan Basin. The warning points of the model proposed in this study were advanced by 73.5 s on average compared with the manual warning points in the three validated fracturing segments, with a successful warning rate of 85.71%, which greatly avoids the possibility of sand screenout and provides a method of fast calculation speed and high prediction accuracy, providing an early warning of sand screenout.

Jet impingement is an efficient rock breaking method in the development of geological resources. In hightemperature formations, thermal stress induced by the temperature difference interacts with fluid pressure and impact forces, thus further enhancing the efficiency of rock failure. Meanwhile, the inherent heterogeneity of rocks influences stress distribution and failure characteristics of rocks as well. To elucidate this intricate process, a multi-physics coupling model is developed in the present study, in which the finite-discrete-element method (FDEM) and Weibull distribution are employed to describe the mechanical response and heterogeneity of rocks. The evolution of temperature, stress, and crack propagation are computed to reveal rock failure mechanisms under different formation conditions and jet parameters. The findings indicate that increasing jet pressure markedly increases jet velocity, improves heat transfer efficiency, and changes the transition from heat conduction to convective heat transfer. Thereby, greater thermal stress is induced, which is accompanied by the application of increased jet pressure on the rock surface. The combined effects of these two factors result in an initial decrease followed by a subsequent increase in crack length. Although rock temperature has fewer effects on jet velocity, the heat transfer efficiency also increases at elevated temperatures resulting from the variation of temperature differences. Correspondingly, thermal stress and crack length rise continually. Moreover, heightened heterogeneity exacerbates rock damage. In this research, thermal stress exerts pronounced effects on crack length once rock temperature exceeds 200 degrees C on the whole. However, the heightened rock heterogeneity can lower the critical temperature threshold for the propagation of cracks. The results of this investigation provide an in-depth insight into the rock failure mechanism influenced by multi-physics coupling.

The heterogeneity of the reservoir plays a crucial role in influencing the propagation of multi-cluster hydraulic fractures in horizontal wells. To explore this impact, a seepage-stress-damage coupled model was developed in this study for analyzing the competitive propagation of multi-cluster fractures utilizing the finite-discrete element method. Utilizing the model, a random assignment program has been developed to establish the coupling distribution of mechanical parameters between matrix elements and discrete elements for characterizing the reservoir heterogeneity. Simultaneously, a wellbore flow model describing the pressure drop of fracturing fluid flow is developed by introducing pipe flow element and fluid connection element, enabling the realization of dynamic flow distribution. Based on the developed model, an investigation is conducted into the impact of pumping rates, fracturing fluid viscosity, and perforation parameters on the fracture propagation of multi-cluster fracturing. The study findings suggest that as reservoir heterogeneity increases, the distribution of rock strength becomes more uneven, resulting in a more complex morphology of fracture propagation. Higher pumping rates lead to elevated pressure within fractures, thereby facilitating the uniform propagation of multi-cluster fractures, particularly in reservoir characterized by medium to high heterogeneity. Increasing the viscosity of fracturing fluid can diminish the tortuosity of multi-cluster fracture propagation, albeit with a somewhat limited enhancement in uniformity. As reservoir heterogeneity intensifies, the interference between fractures escalates, necessitating a reduced number of perforations to heighten perforation friction and enhance the balanced propagation of multi-cluster fractures. This research offers theoretical guidance and a scientific foundation for the design of schemes and optimization of parameters in staged multi-cluster fracturing technology for horizontal wells in heterogeneous reservoirs.

Unconventional oil and gas reservoirs are characterized by factors such as deep burial, high rock strength, and significant geostress differences, which result in slow drilling speeds, high fracturing difficulty, and other issues, requiring urgent solutions. Currently, full-scale drilling and completion simulation wellbores both domestically and internationally are still incomplete in detecting real operational parameters, making it difficult to effectively support the development of new technologies and equipment with key test conclusions. This study designs an intelligent drilling and completion simulation experimental system and focuses on the structural design and sensor layout for the high-pressure simulated wellbore. Through hydraulic simulation, the pressure gradient distribution and pressure wave propagation patterns of the simulated wellbore are analyzed. Based on the simulation results, it was determined that the installation accuracy of the pressure sensors should not be lower than 0.01%, and the maximum installation distance should be 2.5 m.

Based on the finite-discrete element method,a three-dimensional numerical model for axial impact rock breaking was established and validated.A computational method for energy conversion during impact rock breaking was proposed,and the effects of conical tooth forward rake angle,rock temperature,and impact velocity on rock breaking characteristics and energy transfer laws were analyzed.The results show that during single impact rock breaking with conical tooth bits,merely 7.52％to 12.51％of the energy is utilized for rock breaking,while a significant 57.26％to 78.10％is dissipated as frictional loss.An insufficient forward rake angle increases tooth penetration depth and frictional loss,whereas an excessive forward rake angle reduces penetration capability,causing bit rebound and greater energy absorption by the drill rod.Thus,an optimal forward rake angle exists.Regarding environmental factors,high temperatures significantly enhance impact-induced rock breaking.Thermal damage from high temperatures reduces rock strength and inhibits its energy absorption.Finally,higher impact velocities intensify rock damage,yet excessively high velocities increase frictional loss and reduce the proportion of energy absorbed by the rock,thereby failing to substantially improve rock breaking efficiency.An optimal impact velocity exists.

In this chapter, the 3D vibration control equations of infinitesimal riser-test pipe (RTS) will be established through the energy method and Hamilton variational principle. The infinitesimal segment of the RTS is too short, such that it can be regarded as a straight segment. Because the vibration data of deep-water RTS cannot be accurately measured onsite, a simulation experiment was performed to validate the nonlinear vibration model in this study. Three criteria should be satisfied for the similarity experiment of RTS vibration: geometric similarity, motion similarity, and dynamic similarity. According to the parameters of BY5-2-1 well in the South China Sea and the proposed nonlinear vibration model, the results of marine fluid motion, platform heave motion, and RTS vibration response are obtained, and the vibration characteristics of RTS in deep-water are analyzed.

The low-carbon transformation of decommissioned offshore oil and gas platforms is an optimal model for intensive resource utilization and for fully exploiting the economic and ecological benefits of decommissioned platforms. It is also an important measure to maintain and enhance the carbon reduction capacity of the marine sector. However, the green and low-carbon development process in China’s marine sector is just beginning, and the low-carbon transformation of decommissioned offshore oil and gas platforms mostly remains at the conceptual stage, urgently requiring practical and feasible comprehensive transformation plans based on low-carbon technologies. This study completes a survey and analysis of the current status of the disposal of decommissioned oil and gas platforms in China and the level of low-carbon technologies. It proposes a main form of transformation for constructing an offshore carbon recycling hub and three low-carbon transformation routes, clarifying key engineering implementation strategies for platform transformation, including platform safety assessment, selection strategies for transformation plans, and full lifecycle environmental protection. In response to practical issues such as the lack of regulations and policies for platform transformation, shortcomings in the application of low-carbon technologies in the marine sector, and unclear cross-industry cooperation mechanisms, it is recommended to improve platform transformation regulations and guiding policies. It is also necessary to focus on the offshore application performance of core technical equipment, optimize theoretical support for technology, and accelerate the transformation of domestic equipment. Priority should be given to carrying out demonstration projects for the transformation of decommissioned platforms to promote the low-carbon transformation process of decommissioned offshore platforms in China.

To strengthen its energy sector and realize the carbon peaking and carbon neutrality goals,China needs to accelerate the construction of a modern energy system,transform its energy development mode,and improve its energy production support capabilities.The integration and complementarity of multiple energy sources is an effective concept and scheme to solve the separation of energy subsystems,optimize the energy pattern,and improve the efficiency of clean energy utilization.Based on the analysis of the existing modes of multi-energy integration,this study summarizes the development status and bottlenecks of multi-energy integration in China and the development trend of multi-energy integration in other countries.Considering existing models,a new multi-energy integration model that integrates energy conversion,complementarity,reuse,and zero-carbon production is proposed to achieve the clean and efficient utilization of energy.To promote the planning,construction,and practice of multi-energy integration in China,we further propose a basic development path and the following suggestions:(1)formulating a medium-and long-term plan to support multi-energy integration based on resource endowment,(2)accelerating the breakthroughs in key core technologies for multi-energy integration to improve the reliability of equipment,(3)strengthening the training of talents related to multi-energy integration,and(4)optimizing the structure of the multi-energy integration industrial chain.

Disc pumps have obvious advantages in dealing with difficult-to-pump media. Energy efficiency and sustainable energy management are important topics with regard to reducing costs and promoting carbon neutrality. Though the concept of the disc pump was proposed in the 1850s, development was slow and limited by its initial model. However, with the development of industries such as petrochemicals and food, the efficient pumping of difficult-to-pump media is much needed, but facing challenges. Therefore, research on energy-efficient disc pumps is particularly important moving forward. In this paper, the available information from the open literature about the research and development of the disc pump will be thoroughly reviewed. It focuses on the historical development, energy efficiency and physical model application of the disc pump. The review ends with a proposal for the direction of future development, and in this aspect, it is proposed that the energy efficiency prediction model based on velocity slip theory, the energy management system based on multi-scenarios and the design method based on energy conversion theory are important. The latest achievements in energy conversion are given. This review also provides a new perspective for the development of energy-efficient disc pumps.

At present, the traction force and traction speed of the drilling robot cannot be controlled. However, if the speed of the drilling robot is too high, the bit will be damaged because of the shock load. If the speed of the drilling robot is too low, the drilling efficiency will be very low. The existing control system and control algorithm of the drilling robot cannot meet the requirements of the drilling conditions. A control system of the weight on bit and the rate of penetration of the drilling robot was invented. On the basis, a dual-loop fuzzy proportional integral derivative (PID) control algorithm of the pressure difference and flow rate was proposed to control the weight on bit and rate of penetration. Furthermore, the simulation model of the dual-loop fuzzy PID control algorithm was established. It is found that the proposed dual-loop fuzzy PID control algorithm has the characteristics of small overshoot and good tracking. Furthermore, the correctness of the theory was verified by the experiments. The experiments show that the average amplitude of rate of penetration vibration by using adaptive PID controller is less than 50% of that of PID controller. The maximum weight on bit with the adaptive PID controller is only 45.94% of that of the conventional PID controller. The overshoot of the adaptive PID controller is only 24.07% of that of the conventional PID controller. At the same time, the vibration amplitude of the conventional PID controller is obviously larger than that of the adaptive PID controller. The proposed adaptive PID controller in this paper can effectively reduce the vibration of the bit. By reducing the vibration of the bit, the life of the bit can be extended. Finally, it is of great significance to realize the efficient and intelligent drilling process.

In order to ensure the reliability of drilling tractor in the downhole operation, three high‐temperature and high‐pressure sealing mechanisms are designed in this paper to balance the pressure difference between the inside and outside of the drilling tractor, namely the triangular, the U‐shaped and the right‐angle combined sealing structure. In this paper, three models of combined sealing structures are established, the contact stress of different contact surfaces of the three combined sealing structures is analysed by simulation method, and their sealing performance is studied and compared. By comprehensively comparing the effects of pre‐compression ratio, working medium pressure and reciprocating motion on the sealing effect of the three combined sealing structures, the optimal combined sealing structure of the drilling tractor is selected as the U‐shaped combined sealing structure. The research results of this paper can provide reference and theoretical basis for the design and selection of the combined sealing structure.

The Yingqiong Basin in the northern part of the South China Sea is a region with large natural gas reserves. However, the high formation pressure and hydrostatic column pressure of the extra-thick mudstone section in this area present significant challenges to drilling operations. The mudstone has high plasticity and is very hard, and its thickness accounts for only 40% of the total footage, which results in pure drilling time accounting for over 75% of the total drilling time. To accelerate the rate of penetration (ROP) in this area, this study investigates the rock mechanics characteristics of mudstone under high confining pressure through experimental methods. The study reveals that the strength of the mudstone increases rapidly with increasing confining pressure, and the critical transformation stress of bottom-hole mudstone is around 45 MPa. Moreover, a cylindrical-cutter micro bit was developed, and the drillability of mudstone was tested under high confining pressure and hydrostatic column pressure, which further confirms that 45 MPa is the critical stress for a sudden increase in mudstone's drillability. Based on multiple regression analysis, the acoustic interval transit time, hydrostatic column pressure, and argillaceous content were identified as strong correlation parameters for the drillability of plastic mudstones. A new model for evaluating rock drillability considering rock plasticity and chip hold down effect caused by hydrostatic column pressure was developed, which provides effective guidance for the optimal design of bits and drilling fluid density in the extra-thick mudstone formations of the Yingqiong Basin. This study provides theoretical and technical support for the economic and efficient development of high-pressure gas fields in this area.

Bionic soft robotic hand has been developed rapidly, as it can achieve considerable flexibility and mimic human hand to perform actions, such as grasping. This study develops a novel bionic soft robotic hand, which consists of a palm and five fingers that can operate independently. Unlike other soft hands, the fingers of the developed soft robotic hand are capable of stretching and bending. The thumb can mimic the joint activities of human thumb. An air chamber is placed on the back of robotic hand to mimic the elongation of muscles on the back of human hand. As such, the curvature of the palm can be changed. A particle jamming method is used in the hand palm to achieve passive variable stiffness during grasping, which improves the grasping stability of the bionic hand and the ability of wrapping target objects. Grasping experiments are conducted to evaluate and validate the grasping performance of the developed soft robotic hand. The experimental results show that the developed soft hand can effectively grasp sheet, columnar, and irregular objects when the driving pressure of finger and hand back is 50 and 40 kPa, respectively. The maximum grasping mass is comparable to the mass of the soft robotic hand.

Purpose The purpose of this paper is to study the multi-phase flow behaviors in solid fluidization exploitation of natural gas hydrate (NGH) and its effect on the engineering safety. Design/methodology/approach In this paper, a multi-phase flow model considering the endothermic decomposition of hydrate is established and finite difference method is used to solve the mathematical model. The model is validated by reproducing the field test data of a well in Shenhu Sea area. Besides, optimization of design parameters is presented to ensure engineering safety during the solid fluidization exploitation of NGH in South China Sea. Findings To ensure the engineering safety during solid fluidization exploitation of marine NGH, taking the test well as an example, a drilling flow rate range of 40–50 L/s, drilling fluid density range of 1.2–1.23 g/cm3 and rate of penetration (ROP) range of 10–20 m/h should be recommended. Besides, pre-cooled drilling fluid is also helpful for inhibiting hydrate decomposition. Originality/value Systematic research on the effect of multiphase flow behaviors on the engineering safety is scare, especially for the solid fluidization exploitation of NGH in South China Sea. With the growing demand for energy, it is of great significance to ensure the engineering safety before the large-scale extraction of commercial gas from hydrate deposits. The result of this study can provide profound theoretical bases and valuable technical guidance for the commercial solid fluidization exploitation of NGH in South China Sea.