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Abstract:Uranium resources are important strategic resources and energy minerals. In view of the current situation where uranium drilling equipment struggles to meet the requirements for safe， green， and efficient drilling in the new era， this paper systematically reviews the development history of China''s uranium drilling equipment since the 21st century. By comparing domestic and foreign equipment， the core problems existing in the current industry are pointed out： spindle drill rigs with low automation are still the main equipment for sandstone uranium exploration drilling， resulting in high labor intensity and safety risks； the equipment system for in-situ leaching （ISL） uranium drilling is incomplete， with prominent contradictions between efficiency and energy consumption； equipment mobilization in special terrain areas is difficult， and drilling fluid solid control technology is backward. To address these bottlenecks， this paper puts forward development suggestions for the next three years， including： carrying out automation and digitalization upgrades for spindle drill rigs and derricks； developing high-efficiency and low-cost construction equipment for hard-to-access areas； deepening research on intelligent solid control technology for drilling fluids； and strengthening the introduction and promotion of advanced and mature process equipment such as fully-hydraulic drill rigs and wireline coring technology. This study provides a scientific basis and a technical pathway for promoting the upgrading of China''s uranium drilling equipment and has important reference value for advancing the technological progress of the geological drilling industry.

Abstract:The sidewall coring technology is a remedial technical method for oil and gas reservoir evaluation and resource exploration. Its development has spanned nearly a century， gradually evolving from the early impact coring to the high-efficiency and precise rotary sidewall coring technology. This paper systematically reviews the evolution of the sidewall coring technology， focusing on the research progress and key technological breakthroughs of the rotary technology at home and abroad. By comparing and analyzing the technical parameters and application cases of international oilfield service giants and domestic enterprises， it reveals that foreign countries have a leading edge in aspects such as core size， temperature and pressure resistance， fluid-sealing sampling， and core digital processing. Although domestic enterprises have made remarkable progress in mechanical structure optimization， electric direct-drive technology， and temperature-resistant performance， there are still gaps in instrument reliability， adaptability to complex formations， and intelligence level. Based on the current technical bottlenecks and combining with the exploration needs of deep-earth and deep-sea areas， this paper proposes the future research and development directions of sidewall coring. The research results aim to promote the upgrading of Chinese sidewall coring technology towards high-efficiency， intelligence， and digitization， providing key technical support for ultra-deep well and unconventional oil and gas exploration.

Abstract:Soft soil regions are characterized by high water content， large void ratio， low bearing capacity， and high compressibility. Traditional pile foundations often face challenges such as poor construction quality and low bearing efficiency in such ground. The cast-in-place concrete large-diameter pipe pile （PCC pile）， as a novel foundation technology suitable for soft soil improvement， has its mechanical behavior critically important for engineering safety and performance. This paper systematically reviews the research progress on the mechanical behavior of PCC piles， including internal friction resistance， negative skin friction， vertical bearing， horizontal bearing， and pull-out resistance. It summarizes findings from multiple technical approaches， such as laboratory model tests， field tests， finite element and discrete element numerical simulations， and theoretical derivations. The influencing factors， distribution patterns， and calculation methods for each mechanical characteristic are clarified. Analysis indicates that current research still has shortcomings in the quantitative characterization of internal friction resistance， the time-dependent evolution mechanism of negative skin friction， the response under complex loading conditions， and pile group interaction effects. Future research should focus on the coupling of multiple methods， refined modeling， and validation through engineering field measurements to enhance the scientific basis and practical applicability of PCC pile design， thereby promoting broader application of this technology in high-speed railways， port engineering， anti-floating structures， and related fields.

Abstract:To address the dual challenges of global carbon emissions and industrial solid waste disposal， this study proposes an integrated "carbon sequestration-solid waste disposal-abandoned cavity utilization" three-in-one engineering scheme. This scheme combines abandoned cavities from Underground Coal Gasification （UCG） with fly ash mineralization for CO₂ sequestration. Using CMG-STARS software， a 3D， three-phase， five-component coupled model was developed to simulate the thermodynamic and mineralization behaviors during the injection of fly ash slurry and CO₂. The study focused on the effects of different CO₂ injection rates on temperature field evolution and sequestration efficiency. The results indicate that increasing the CO₂ injection rate significantly enhances the intensity and spatial uniformity of the mineralization reaction. For the same total injection volume， increasing the rate from 20000 m3/d to 60000 m3/d improves the sequestration efficiency by approximately 15%. While the injection of low-temperature CO₂ initially causes a cooling effect， the exothermic nature of the mineralization reaction gradually reverses this trend， stabilizing the temperature at approximately 250 ℃. This study provides a theoretical basis and parameter optimization strategies for the development of this integrated engineering technology.

Abstract:The ballooning effect is a common and complex flow phenomenon during drilling， characterized by periodic loss and backflow of drilling fluid. It is often confused with well influx and poses a significant threat to well control safety. Based on a systematic review of relevant studies， this paper categorizes the formation ballooning effect into four types—borehole elastic deformation， drilling fluid expansion-contraction， fracture-induced breathing， and permeability-induced breathing—and analyzes their triggering mechanisms， identification characteristics， and applicable conditions. For identification， typical methods such as Pressure While Drilling （PWD）， resistivity logging， decision tree analysis， and event tree analysis are reviewed， and their adaptability to different mechanisms is assessed. In terms of control， strategies including managed pressure drilling， continuous circulation systems， and drilling fluid parameter optimization are summarized， and their effectiveness across different breathing types is discussed. This study aims to establish a systematic cognitive framework for understanding the ballooning effect， providing theoretical support and practical guidance for accurate identification and scientific response under complex downhole conditions.

Abstract:Water-rock interaction（WRI） during Hot Dry Rock （HDR） exploitation is a critical factor affecting the long-term stability of geothermal reservoirs. To address the challenge that conventional experimental methods struggle to simultaneously simulate long-term effects while preserving sample integrity， this study introduces a self-developed high-temperature and high-pressure WRI simulation device. Using an acidic solution as an accelerating medium， dynamic interaction experiments on granite samples were conducted for 3， 6， and 9 days. Through a combination of nuclear magnetic resonance， thermal conductivity analysis， and mechanical testing， this research systematically reveals the synergistic degradation mechanism of the granite''s pore structure and thermo-mechanical properties under acidic conditions. The results demonstrate that acidic WRI leads to a non-linear and dramatic increase in granite porosity （by 448% within 9 days）， with a shift in pore size distribution from predominantly micropores to a higher proportion of meso-and macropores. The deterioration of the pore structure induces a significant decline in thermal conductivity and uniaxial compressive strength， which decrease by 8.63% and 33.19%， respectively， over the same 9-day period， showing highly consistent evolutionary trends. This study successfully establishes a quantitative link between short-term accelerated laboratory simulations and long-term in-situ evolutionary behavior， providing crucial experimental data and theoretical support for accurately predicting the physical-mechanical behavior of HDR reservoirs during their service life， assessing their long-term stability， and ultimately ensuring the safe and efficient development of geothermal resources.

Abstract:In drilling engineering， failures at the threaded connections of drill pipe joints account for up to 86%， making them the primary risk area for drill string failure. To conduct an in-depth analysis of joint stress distribution and concentration characteristics， this study， based on 3D finite element simulation， performed a comparative analysis of the stress in API standard single-shoulder and double-shoulder drill string joints under axial and torsional loads. Furthermore， the axial and torsional stress concentration coefficients for the NC50-type joint were calculated. The findings indicate that： the maximum stress in single-shoulder threads is concentrated at the root of the first thread in the thread engagement area； the maximum axial and shear stresses in double-shoulder threads are significantly lower than those in single-shoulder threads， with reductions of approximately 24% and 27.3%， respectively， exhibiting a more pronounced performance advantage， especially under high torque； the axial stress concentration coefficient for the NC50 joint is 4.21， and the torsional stress concentration coefficient is 3.73. The outcomes of this research provide a significant basis for the performance optimization design of drill pipe joints， precise stress calculation of the drilling system， and fatigue life prediction.

Abstract:To address the engineering challenges of frequent failure and short service life of roller cone bits in hard formation drilling， this study established a nonlinear contact dynamic model between the bit and rock based on field drilling data. The Drucker-Prager criterion was adopted to describe the elastoplastic behavior of the rock. The rock-breaking process of a tri-cone bit under the coupled effects of weight on bit （WOB） and rotary speed was simulated using the finite element software ABAQUS. The results indicate that rock breakage is primarily achieved through impact and shear， with the induced tensile stress being the dominant factor in rock failure. Pronounced longitudinal and torsional vibrations occur during the rock-breaking process， and the resulting transient impacts are the root cause of accelerated tooth wear and bearing failure. This conclusion is consistent with field failure cases. The research reveals the failure mechanism of roller cone bits in hard formations and proposes recommendations such as preferentially selecting wear-resistant bits， installing shock absorbers， and optimizing drilling parameters. These findings provide important theoretical guidance and practical value for enhancing drilling efficiency in deep hard formations and reducing engineering costs.

Abstract:To enhance the efficiency of deep and extra-deep hole drilling， this study established a drilling time utilization model based on the time allocation of drilling processes. Using this model， we quantitatively analyzed the impact of various factors on drilling time for a 13000 m extra-deep hole， comparing wireline coring with conventional coring. The analysis reveals that regardless of the drilling method， penetration per round trip is the primary factor influencing drilling time. However， the ranking of subsequent factors differs： for wireline coring， the key subsequent factors are bit life， drill-pipe stand length， and tripping speed， in that order； for conventional coring， they are drill-pipe stand length， tripping speed， and wellhead handling time. The study further confirms that wireline coring is significantly more efficient than conventional coring， but the performance gap can be effectively narrowed by optimizing key parameters such as penetration per round trip. This research reveals the critical factors and optimization pathways for drilling time in extra-deep hole drilling， providing a theoretical foundation for the evaluation of drilling methods and the enhancement of drilling efficiency.

Abstract:To address the technical challenge of cement slurry lost circulation and low return during cementing operations， this study focuses on enhancing the self-sealing capability of the cement slurry itself. A novel anti-leakage cement slurry system was developed in this work. Initially， a fully sealed leakage evaluation apparatus was developed based on the modification of the API fluid loss tester， and a corresponding evaluation methodology was established. Guided by a synergistic anti-leakage mechanism of "rigid bridging， elastic filling， and fiber network capturing"， a novel lost circulation material， ZJY-1， was optimized through systematic material selection and orthogonal experiments. ZJY-1 is a composite of rigid particles， temperature-sensitive deformable particles， and composite fibers. Laboratory evaluations demonstrate that ZJY-1 exhibits excellent compatibility with both conventional and high-temperature cement slurry systems. While effectively maintaining key engineering properties such as rheology， free fluid， and compressive strength of the set cement， this material enhances the sealing pressure-bearing capacity for 1 mm pores and fractures to 7 MPa. Its thickening time can be flexibly adjusted by using retarders， and its overall performance surpasses that of the commercial materials used for comparison. This research provides effective technical support for achieving dynamic leak sealing during cementing， simplifying the cementing process， and improving cementing quality in complex formations.

Abstract:Drilling fluid is the core medium in drilling engineering and its purification efficiency directly affects drilling efficiency， drilling quality， and the ecological environment. To address the challenge of the cuttings purification， the Russian research team has proposed a technology of drilling fluid purification and cuttings recycling using ultrasonic waves and permanent magnetic fields. Through theoretical analysis， a kinetic model for particle sedimentation under magnetization conditions has been established. A closed-loop treatment apparatus， integrating an ultrasonic radiator and a П-shaped magnet， has been designed and subsequently subjected to both laboratory and field tests. The results of the tests demonstrate that this technology can promote the formation of stable "cluster structures" of cuttings particles in the drilling fluid， significantly enhancing their sedimentation rate and effectively improving the fluid''s rheological properties， leading to 50% reduction in fluid loss， 20% increase in viscosity， and cuttings precipitation rate reaching 30%. Furthermore， the recovered cuttings can be calcined to produce fracturing proppants， achieving resource utilization. These results provide a new innovative solution way for resolving the problems of drilling fluid purification and cuttings pollution and have significant reference value for promoting greening of drilling engineering.

Abstract:To address the challenges of low efficiency associated with traditional vertical boreholes and the inability of conventional directional drilling tools to achieve continuous coring in deep-buried water conveyance tunnel exploration， a novel directional drilling continuous coring tool was developed based on wireline coring and directional drilling technologies. An indoor drilling test platform was established to validate the tool''s performance in directional deflection and continuous coring. The results demonstrate that the tool operates stably， successfully achieving directional drilling and high-quality continuous coring. The actual deflection capability reached 3.50°/30 m， closely aligned with the theoretical calculation. The core recovery rate was as high as 93%~98%， with a Rock Quality Designation （RQD） value ranging from 80% to 91%. This research provides an efficient and reliable technical solution for the exploration of deep-buried long tunnels and holds significant importance for advancing the development of directional drilling continuous coring technology.

Abstract:Addressing the severe coal dust hazard at the orifice of gas drainage boreholes in deep coal mines and the low efficiency of conventional dust control technologies， this study aims to develop a high-efficiency， eco-friendly composite dust suppressant with a synergistic dust suppression mechanism. A graft copolymer （PSA） was synthesized via graft copolymerization using sodium alginate， polyvinyl alcohol， and acrylamide as raw materials. A novel composite dust suppressant （PSAA） was then formulated by compounding PSA with the surfactant APG0810. The structure and thermal stability of PSA were characterized by Fourier Transform Infrared Spectroscopy （FTIR） and Thermogravimetric Analysis （TGA）. The dust suppression performance of PSAA was evaluated through a series of experiments， including sedimentation experiments， contact angle measurement， and anti-evaporation and wind erosion resistance tests. The results indicate that PSA possesses excellent thermal stability. The PSAA solution demonstrated outstanding wettability， exhibiting a contact angle as low as 24° with the coal sample， a 61.9% reduction compared to that of water. It also showed significant moisture retention at 50 °C and a wind erosion resistance rate of 81.73% even under strong wind conditions of 9 m/s. Scanning Electron Microscopy （SEM） confirmed that PSAA forms a dense， consolidated layer on the coal dust surface， achieving a synergistic "wetting-bonding-curing" dust suppression effect. This novel dust suppressant is characterized by a simple preparation process and superior performance， offering a new technical approach and solution for the effective control of coal dust at the orifice of gas drainage boreholes.

Abstract:Coastal geological surveys play a pivotal role in understanding resource distribution and ecological conditions in China''s coastal regions， promoting urbanization development， ensuring sustainable economic growth， and addressing frequent natural disasters. The Marine Geology No. 17 Vessel， independently designed and constructed by China， is a small-displacement integrated coastal geological survey vessel. It fills a critical gap in China''s capabilities in this field and significantly enhances the nation''s coastal geological survey capacity. The vessel''s drilling system is equipped with multiple coring tools tailored to different stratigraphic layers， and emergency safety protocols have been established specifically for coastal drilling operations. The system successfully completed a 140m deep drilling task in the western waters of the North Yellow Sea， achieving a core recovery rate of 92.7%. Field applications have demonstrated that the drilling system of the Marine Geology No. 17 Vessel can effectively fulfill coastal geological survey drilling and coring missions.

Abstract:During the 14th Five-Year Plan period， a large number of small-diameter PVC groundwater monitoring wells have been deployed nationwide to monitor the environmental quality of groundwater in unconfined aquifers， as part of efforts targeting the "dual-source" inventory and groundwater environmental monitoring. The bottoms and inner walls of these groundwater monitoring wells often become clogged due to sediment and impurity deposition. This paper focuses on the challenges of maintaining and clearing silt in small-diameter groundwater monitoring wells. A portable equipment integrated with air lift reverse circulation dredging technology was designed and developed， and the system composition and technical principles of the portable dredging equipment were elaborated. Simulation analysis results based on a simplified Euler''s three-phase flow model and statistical data on the dredging effectiveness of the equipment system for monitoring wells of different depths and various types of sediment indicated that the developed system significantly improves dredging efficiency for wells of varying depths. The sedimentation rate in monitoring wells is significantly correlated with the properties of soil particles in the groundwater. The predicted outcomes from numerical simulations are generally consistent with the measured data from engineering practices in terms of overall trends， with actual engineering results outperforming the predictions. This integrated equipment system addresses the challenges of maintaining and dredging small-diameter groundwater monitoring wells in the ecological and environmental sector， significantly extends the service life of monitoring wells， and delivers notable economic benefits.

Abstract:To investigate the deep metallogenic regularities of the Xiaoqinling gold field， a 3500 m scientific deep borehole was deployed in the geologically complex Xiaohe Fault Zone. The drilling operation encountered severe challenges， including borehole constriction in fault gouge， collapse in fractured zones， and stuck pipe due to high ground stress， leading to frequent downhole incidents where conventional drilling techniques proved inadequate. This paper presents the successful application of the XD-40DB AC variable frequency top-drive core drilling rig. By leveraging its core technological advantages—such as intelligent integrated control， an 18m long-stroke feed system， and precise power regulation—in conjunction with an optimized five-section borehole structure， multiple targeted drilling fluid systems， and meticulous parameter control， a comprehensive construction technology applicable to extra-deep boreholes in complex formations was developed. This technological system effectively overcame challenges like borehole instability and stuck pipe， achieving a final depth of 3491.90 m and an average core recovery rate of 97.18%， thereby successfully fulfilling the geological objectives. The findings not only provide crucial geological data for studying the ore-controlling mechanism of the Xiaohe Fault but also validate the exceptional performance and pivotal supporting role of top-drive core drilling rigs in deep exploration within complex formations， offering a significant technical demonstration and practical experience for similar extra-deep drilling projects in China.

Abstract:Xizang Luobusha working area is located at a high altitude with complex geological conditions， featuring fractured rock layers and significant fissure development， resulting in poor formation stability and drilling challenges such as strata fragmentation， leakage， and shrinkage. This paper focuses on the construction practice of medium-deep holes designed to a depth of 800 m in this working area， summarizing the construction process in extremely complex formations dominated by fractured chlorite petrified olivine， which suffer from severe leakage and frequent shrinkage. To address core challenges such as personnel shortages， special equipment assembly requirements， hole wall instability caused by severe leakage， flushing fluid contamination and failure， and frequent shrinkage leading to stuck bits， the key technologies were systematically summarized， including innovative combination technologies of drilling rigs and drill towers， optimization of flushing fluid systems based on dynamic plugging and anti-contamination formulations， casing protection combined with periodic drilling and hole sweeping to prevent shrinkage， and phased dynamic personnel adjustment and rapid training models. Through practical verification， this drilling operation successfully overcame various difficulties and completed the hole smoothly. The case study provides technical reference and management experience for core drilling under similar conditions of high altitude and complex strata.

Abstract:In response to the hole-inside accidents such as drill jamming and burying caused by hole shrinkage and chipping encountered during drilling in the complex strata of Jinchuan mining area， which are characterized by strong water sensitivity， intense fragmentation， severe water inrush， and high ground stress， requirements for the flushing fluid have been set， including low water loss， strong inhibition， strong sealing， appropriate density， and excellent rheological properties. Firstly， suitable flushing fluid treatment agents were selected， including the water loss reducing inhibitor FLI-1， the sealing and anti-collapse agent FDC-1， the inhibitor LHK， and the sealing agent FG-1. Then， through orthogonal experiments， a flushing fluid formula suitable for the complex strata of Jinchuan mining area was developed， and the conventional performance， inhibition， sealing， and lubricity of the formulated flushing fluid were evaluated. The results of field application tests showed that this flushing fluid formula possesses excellent rheological properties， along with good inhibition， sealing， and lubricity. It can effectively prevent drilling accidents caused by complex strata encountered in the mining area drilling， improve drilling efficiency， and support drilling construction in the mining area.

Abstract:This study is set against the background of coal fire control in Xinjiang. Drawing on international engineering experience with closed-loop geothermal systems （CLGS） such as Eavor-Loop， it aims to achieve dual objectives： extracting underground thermal energy to cool coal fire zones， thereby facilitating the recovery of coal resources in burned-out areas， and utilizing the geothermal energy obtained. A closed dual horizontal well heat extraction scheme was adopted， featuring a five-section well trajectory design- "build-up+tangent+horizontal+build-up+tangent". In response to the high-temperature and fractured formation characteristics of the coal fire area， an innovative "small-diameter pilot hole+large-diameter back-reaming" process was employed during implementation. This approach proposes an efficient and low-cost drilling and heat extraction technical solution suitable for high-temperature rock mass underground thermal energy reservoirs in the Liuhuanggou coalfield fire area. In order to solve the problems of high temperature （>170 ℃）， unstable strata and large inclination in the whole well， various drilling and completion techniques are adopted， the drilling fluid system and equipment are optimized， and the high temperature measuring instruments and downhole power tools are applied. As a result， issues such as loose and fractured formations， lost circulation， and abnormal high temperatures when drilling through the coal fire zone were successfully resolved. This work establishes a replicable technical paradigm for future drilling and completion operations in coal fire areas.

Abstract:This study investigates the Bangting Formation landslide in Wuhe Township， Tengchong City， Yunnan Province， China， systematically analyzing the coupling relationship between landslide deformation data curves and geomechanical mechanisms through geological surveys， monitoring data， and numerical simulations. The research reveals a significant nonlinear correlation between landslide displacement responses and rainfall intensity as well as pore water pressure variations， with deformation mechanisms driven by stratigraphic permeability differences， human engineering activities， and river erosion. By constructing the hydro-mechanical coupling model， the multi-stage deformation characteristics of landslides and the dynamic response law of geological conditions are revealed， and the "rainfall-infiltration-instability" chain early warning threshold is proposed to provide theoretical support and technical paradigm for regional landslide risk prevention and control.

Abstract:Taking the Wenzhou Kaidi Center super high-rise building project as an example， this paper discusses the process of determining the bearing capacity of its ultra-deep large-diameter cast-in-place piles. Through the collaborative application of multiple technology chains—including the combined rotary drilling and percussion drilling hole-forming technique， reverse circulation slag removal and mud purification technology， hole-bottom sediment detection technology， concrete pouring quality assurance technology， and two-stage pile bottom grouting technolog—the verticality of the pile holes， the thickness of sediment at the hole bottom， the quality of pile concrete， and the mobilization of bearing capacity in the load-bearing layer are effectively ensured. This provides important technical support for achieving the designed bearing capacity of ultra-deep large-diameter cast-in-place piles in super high-rise buildings. Furthermore， by employing the cross-hole sonic logging detection method with embedded pipes and ultra-high-tonnage static load testing technology， reliable safety assurance is provided for verifying the integrity and bearing capacity of ultra-high-tonnage， ultra-deep cast-in-place piles in super high-rise structures. This paper offers valuable insights for the design and performance realization of ultra-large-tonnage， ultra-deep large-diameter cast-in-place piles in super high-rise buildings.

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