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YUE Wen, LIANG Jian, ZHANG Hengchun, ZHU Lijuan, ZHU Lina, WANG Zhiqiao, WANG Yu, JIA Jianbo, XUE Qilong, LIU Fan, XU Liang, WANG Jinyin
2026,53(4):1-13, DOI: 10.12143/j.ztgc.2026.04.001
Abstract:
Continental scientific drilling in ultra-deep wells is a crucial approach to revealing the deep Earth''s material composition， tectonic evolution， and resource potential， and cores serve as the first-hand physical evidence for interpreting stratigraphic information. As the core technology for highly efficient core acquisition， wireline coring directly determines coring quality and drilling efficiency. However， drilling beyond 10，000 meters， subjected to the combined effects of ultra-high temperature， ultra-high pressure， high stress， and complex formations， is prone to causing shortened bit life， seal failures， core jamming， and an increased risk of core loss. Meanwhile， numerous challenges persist， such as the poor strength-to-weight ratio of drill pipes， high wellbore friction， insufficient output torque of downhole motors， and low feed delivery accuracy. This paper systematically reviews the challenges， advances， and trends of wireline coring technology. It analyzes the technical bottlenecks of coring tools， drill strings， downhole motors， vertical drilling systems， logging-while-drilling （LWD） systems， and dynamic testing platforms under deep extreme working conditions， and summarizes the latest global advances in these fields. The results indicate that although significant breakthroughs have been made in various key technologies， urgent issues still remain to be resolved， including the adaptability of materials to extreme environments， downhole sealing and transmission reliability， and intelligent measurement and control synergy. Future development should rely on multidisciplinary cross-integration and innovation， focusing on developing drilling tool materials capable of withstanding 300 ℃ and 175 MPa， promoting the intelligent integration of smart coring bits， high-temperature-resistant mechanical vertical drilling systems， and coring processes， and constructing a multi-field coupled dynamic testing and evaluation standard system. This will achieve a strategic upgrade from traditional coring technology to intelligent wireline coring technology， providing a solid technical guarantee for 10，000-meter-level scientific drilling projects.
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YIN Yusen, SUN Youhong, XU Shaotao, XU Liang, DOU Shichao, WANG Zhihong
2026,53(4):14-23, DOI: 10.12143/j.ztgc.2026.04.002
Abstract:
To address the challenges encountered during drilling in ultra-deep wells exceeding 10000 m， including low rate of penetration， frequent drilling tool failures， and elevated drilling risks under high-temperature and high-pressure （HTHP） conditions， this paper systematically discusses the major technical difficulties from five aspects： rock brittleness-ductility transition， accelerated bit wear， power transmission attenuation， trajectory control inaccuracy， and high-temperature drilling fluid failure. The results indicate that HTHP conditions in ultra-deep wells alter rock-breaking mechanisms， causing the failure mode to gradually shift from predominantly brittle fracture to coupled brittle-plastic deformation， thereby increasing rock-breaking difficulty. Meanwhile， drill bits are subjected to severe wear and a higher risk of failure under elevated temperatures， heavy loads， and highly abrasive formations， resulting in a shortened service life. Friction and vibration of long drillstring reduce the surface power transmission efficiency， and the performance and operational reliability of downhole motors decline due to the degradation of seals， bearings， and elastomeric components. Vertical drilling tools may experience trajectory control inaccuracies because of performance drift or failure of electronic components under HTHP conditions. In addition， high temperatures can deteriorate the rheological properties of drilling fluids and reduce their filtration performance and stability， thereby weakening their functions in cuttings transport， cooling， and wellbore stabilization. The challenges of drilling ultra-deep wells are characterized by significant multi-factor coupling， and fundamentally arise from the synergistic failure of drilling tool systems and drilling fluids under extreme downhole conditions， particularly the HTHP environments encountered in deep formations. Therefore， further research is needed on multi-physics coupled rock-breaking mechanisms， high-temperature-resistant materials and structural designs for drilling tools， and intelligent drilling fluid systems to support the optimization of drilling processes and tool development for ultra-deep wells.
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CAO Longlong, LIANG Jian, ZHANG Hengchun, ZHU Zhitong, LI Xiaoyang, LI Kuan, WU Jixiu, YAN Jia, SHI Shanshan, ZHAO Junjie, XU Quanwei
2026,53(4):24-35, DOI: 10.12143/j.ztgc.2026.04.003
Abstract:
To meet the development requirements of coring technology for 10000-meter ultra-deep drilling， this paper systematically analyzes four major challenges faced by deep coring-extreme working conditions， equipment adaptability for continuous coring in long well sections， coring efficiency， and well deviation control-based on typical drilling engineering practices both domestically and internationally. It reviews the application status of technologies concerning coring equipment， drill bits， downhole motors， wireline coring， anti-jamming， and deviation control， and comparatively analyzes the advantages， disadvantages， and engineering application effects of different processes. The research indicates that China has made significant progress in the field of deep coring； however， core technologies for efficient and high-quality continuous coring over long well sections under ultra-deep extreme environments still have shortcomings. The study points out that future coring technology will take the efficient and high-quality recovery of deep cores as its fundamental objective， and develop towards the deep integration of automation and intelligence. By constructing an integrated "measurement+control+coring" system， developing high-temperature-resistant downhole motor technologies， and making breakthroughs in ultra-deep wireline coring， core anti-jamming and plug-releasing technologies for long-run coring， as well as intelligent diagnosis and early warning technologies， a new generation of deep coring technology system will be established， providing technical support for China''s deep earth exploration.
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TIAN Longjun, XUE Qilong, WANG Jin, QU Jun
2026,53(4):36-43, DOI: 10.12143/j.ztgc.2026.04.004
Abstract:
As continental scientific drilling advances toward 10000-meter ultra-deep wells， the extreme downhole conditions of temperatures exceeding 300 ℃ and pressures over 175 MPa render electrically-controlled vertical drilling systems ineffective. Featuring a purely mechanical structure and a temperature resistance potential of up to 300 ℃， mechanical vertical drilling technology has become the core solution for deviation prevention and straight-hole drilling in ultra-high temperature deep wells. This paper systematically reviews the working principles and research progress of mechanical vertical drilling technology， comparatively analyzes the structural characteristics and field application performance of representative domestic and international products， and identifies significant gaps between China and foreign countries in deviation correction accuracy， temperature resistance， and engineering maturity. On this basis， three key technical issues are examined： the dynamic response of the mechanical stabilization platform under downhole vibrations， innovative push-the-bit actuators， particularly the bit fluid steering concept， and high-temperature materials and sealing. It is pointed out that existing rib-type push-the-bit systems suffer from the inherent limitation of formation-sensitive steering performance， rib wear， and the degradation of deviation correction accuracy caused by stick-slip vibration affecting the stabilization platform. Future research should focus on improving deviation correction accuracy， developing materials resistant to 300 ℃， investigating multi-field coupled dynamic mechanisms， and advancing domestic engineering applications， thereby promoting a transformative upgrade of the actuator from "rib-type pushing" to "bit fluid steering" and providing technical support for 10000-meter continental scientific drilling projects.
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YIN Hao, LIANG Jian, ZHANG Hua, MA Lin, LI Wei, WANG Wen, WANG Yuewei
2026,53(4):44-52, DOI: 10.12143/j.ztgc.2026.04.005
Abstract:
When the slenderness ratio （L/D） of a drillstring exceeds 50000， it exhibits high flexibility and pronounced nonlinear characteristics. The coupled axial， lateral， and torsional vibrations easily induce issues such as stick-slip， whirling， and parametric resonance， severely compromising the drilling safety and efficiency of ultra-deep wells. Focusing on the dynamic challenges induced by the extreme geometric features of high-slenderness-ratio drillstrings， this paper systematically reviews their nonlinear vibration characteristics， dynamic modeling methods， vibration control strategies， and engineering application challenges. The review indicates that geometric， boundary， and friction nonlinear couplings exist among the axial， lateral， and torsional vibrations， inducing complex phenomena such as the coexistence of forward and backward whirling and stick-slip multi-stability； the finite element method and geometrically exact beam theory prioritize high-fidelity characterization but incur high computational costs； model order reduction and data-driven methods improve computational efficiency， yet the simplification of wave propagation effects requires careful handling； experimental validation is key to model verification， but extrapolation from scaled models to full-scale conditions remains challenging. Currently， research still faces three major scientific problems at the theoretical level： multi-modal energy transfer mechanisms， state-dependent time-delay dynamics， and bifurcation theory of non-smooth systems. At the engineering level， it is urgent to overcome core difficulties such as efficient full-wellbore prediction and dynamic evaluation of extended-reach limits. In the future， this field will evolve towards intelligent dynamics integrating multi-physics coupling， stochastic reliability analysis， data-driven approaches， and digital twins， providing solid scientific support for enhancing the safety and economic performance of ultra-deep geological resource development.
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WANG Yuhang, ZHU Lina, HE Shiwei, ZHAO Yang
2026,53(4):53-65, DOI: 10.12143/j.ztgc.2026.04.006
Abstract:
Titanium alloys exhibit great application potential in deep-earth drilling equipment owing to their low density， high specific strength， and excellent corrosion resistance. However， their inherent drawbacks-such as low hardness， insufficient wear resistance， and susceptibility to high-temperature oxidation-severely restrict large-scale engineering applications downhole. Laser cladding of ceramic particle-reinforced titanium matrix composite coatings is a key surface modification technology to enhance the surface performance of titanium alloys. This paper systematically reviews the research progress on laser cladding modification of titanium alloys. The fundamental principles of laser cladding and the governing effects of process parameters on coating microstructure and properties are elucidated， and the advantages， disadvantages， and applicable conditions of two types of parameter optimization methods-traditional experimental design and intelligent optimization algorithms-are compared. Furthermore， the classification and material selection criteria of ceramic reinforcing phases are systematically reviewed， and research achievements on titanium matrix composite coatings are summarized from three dimensions： wear resistance， corrosion resistance， and high-temperature oxidation resistance. Most existing studies have focused only on single performance tests， while research on coating failure mechanisms under the multi-field coupled environment of "high temperature-wear-corrosion" in deep downhole conditions remains insufficient. Future efforts should be directed toward the intelligent design of cladding powder systems， the development of hybrid auxiliary cladding processes， and the investigation of multi-field coupled failure mechanisms， so as to provide a theoretical basis for the life extension design and service reliability evaluation of titanium alloy drilling tools in deep-earth drilling.
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WANG Ming, XU Liang, XU Shaotao, YIN Yusen, DOU Shichao, ZHU Xingchao
2026,53(4):66-78, DOI: 10.12143/j.ztgc.2026.04.007
Abstract:
The working performance of diamond drill bits faces severe challenges under extreme deep-drilling environments characterized by high temperature， high pressure， high abrasiveness， strong corrosion， and multi-field coupling. This paper systematically reviews the working characteristics and failure mechanisms of PDC bits and impregnated diamond bits under the aforementioned environments. The results indicate that： under high-temperature conditions， PDC bits primarily suffer from thermal damage and interfacial delamination， while impregnated bits exhibit matrix softening and thermal damage to diamond； under high-pressure conditions， PDC bits are prone to cutter fracture and delamination， whereas impregnated bits undergo matrix deformation and diamond particle shedding； under highly abrasive conditions， both types of bits experience synergistic failure caused by abrasive wear and vibration fatigue； under corrosive conditions， PDC bits undergo chemical dissolution and micro-galvanic corrosion， whereas impregnated bits mainly exhibit selective dissolution of the binder phase， and the corrosion-wear synergy significantly accelerates material loss； multi-field coupling promotes mutual reinforcement among various damage mechanisms， producing a nonlinear amplification effect. Correspondingly， the service life of drill bits can be extended or the rock-breaking efficiency can be improved through hydraulic structure optimization and heat-resistant material modification， shaped cutters with jet assistance， bionic structures and ultra-wear-resistant matrices， composition optimization and surface coating， as well as gradient structure design. Future research should focus on deepening the research on multi-field coupling mechanisms， promoting the engineering validation of extreme-environment-specific materials， and developing intelligent drill bit technologies， thereby supporting the iterative upgrades of drilling technologies for extreme deep-earth environments.
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MAO Xinyue, MENG Qingnan, WANG Sifan, YUAN Mu
2026,53(4):79-84, DOI: 10.12143/j.ztgc.2026.04.008
Abstract:
To improve the single-grain compressive strength of diamond and enhance the drilling performance of impregnated diamond bits in hard formations， a molybdenum carbide （Mo?C） coating was prepared on the diamond surface via the molten salt method. Microstructural characterization was conducted using scanning electron microscopy （SEM） and X-ray diffraction （XRD）， the single-grain compressive strength was measured， and finite element simulation was employed to analyze the residual thermal stress induced by the coating and its strengthening mechanism. The results indicate that after holding at 1323 K for 90 min， a continuous and dense Mo?C coating forms on the diamond surface， with an average thickness of approximately 2.38 μm. The single-grain compressive strength of the coated diamond increases from 84 N to 156 N， representing an increment of 85.71%. Finite element simulation reveals that due to the difference in thermal expansion coefficients between Mo?C and diamond during the cooling process， a residual compressive stress of approximately 445.6 MPa is generated within the diamond. Under external loading， this compressive stress counteracts the tensile stress at the crack tip， inhibiting crack initiation and propagation， thereby significantly improving the compressive performance. This study reveals the thermal stress mechanism for the coating-enhanced compressive strength of diamond， providing a theoretical basis and engineering reference for the design and manufacture of high-performance diamond bits.
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CAI Mingjie, MAO Dan, TAN Leichuan, PENG Hao, SUN Niyuan, GUO Maolei, GUO Lite, SUN Yueming
2026,53(4):85-93, DOI: 10.12143/j.ztgc.2026.04.009
Abstract:
To address the issue of strength and stiffness degradation of drill strings under high-temperature conditions in ultra-deep well drilling， which affects drillstring safety and deviation control， high-temperature tensile and thermal expansion tests were conducted on V150-grade drill pipe material. The elastic modulus and yield strength at different temperatures were obtained， and a mathematical model describing their variation with temperature was established. Combined with a transient wellbore temperature field model calibrated with measured data， the temperature distribution along a specific ultra-deep well was analyzed. Integrating the material model and the temperature field model， the effects of parameters such as geothermal gradient， drilling fluid flow rate， drilling fluid density， and inlet temperature on drill pipe performance were systematically investigated. The results show that both the elastic modulus and yield strength of V150 drill pipe decrease significantly with increasing temperature， with the yield strength decreasing by approximately 15% at 250 ℃. Conventional design models， which do not account for this temperature effect， overestimate the actual strength of the drill string. The sensitivity indices of the parameters affecting yield strength follow the order： inlet temperature > drilling fluid flow rate > geothermal gradient > drilling fluid density， while for elastic modulus the order is： geothermal gradient > drilling fluid density > inlet temperature > drilling fluid flow rate. The design of drill strings for ultra-deep wells must consider performance degradation due to high temperatures， and safety can be enhanced by optimizing flow rate and inlet temperature. The research findings provide technical support for the design and operation of drill strings in ultra-deep wells.
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ZHANG Hengchun, ZHU Yongyi, WANG Wenshi, YAN Jia, CAO Longlong, WANG Wen
2026,53(4):94-102, DOI: 10.12143/j.ztgc.2026.04.010
Abstract:
To improve coring efficiency in ultra-deep scientific drilling and address the large-diameter coring requirements of the CCSD-SK-2 East Borehole， systematic research on equipment configuration and tool innovation was carried out. The API drill pipe was modified to achieve an inner drift diameter of ≥112 mm， accommodating both conventional trip coring and wireline coring operations. A 6500 m wireline coring winch featuring a rope-guided spooling mechanism was developed， and various combined coring tools centered on a hollow downhole power tool were innovatively designed. Tests in the ?311.2 mm， ?215.9 mm， and ?152.4 mm boreholes demonstrated the overall feasibility of large-diameter wireline coring technology in deep wells， with the optimized drill pipe and automatic rope spooling mechanism performing well. For boreholes of ?215.9 mm and above， hollow downhole power tools are preferable， whereas conventional "three-in-one" tools suffer from insufficient power. Conventional wireline coring achieved good results in the ?152.4 mm borehole； however， components such as the locking latch and landing device are prone to failure due to cuttings accumulation. This study verifies the technical feasibility of large-diameter wireline coring in deep wells， provides technical reserves for ultra-deep scientific drilling exceeding 10000 m， and proposes targeted optimization suggestions for drilling tools and fluids in ultra-deep well environments.
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2026,53(4):103-112, DOI: 10.12143/j.ztgc.2026.04.011
Abstract:
Urban geological coring drilling serves as a critical method for acquiring subsurface geological information. The complex subsurface geological conditions in Beijing impose higher requirements on core quality， while current drilling operations face challenges such as a lack of standardized procedures and inconsistent core quality. To establish a coring drilling specification system tailored to the urban geological work in the capital， this study reviews the current development status and core challenges of urban geological coring drilling in Beijing. It analyzes the application characteristics and applicable scopes of various techniques， including percussion drilling， conventional rotary drilling， shallow rotary drilling， multi-functional direct-push drilling， and sonic vibration drilling. Based on different scenarios-such as urban land and groundwater environmental investigation， underground space development condition survey， geological hazard investigation， and geo-environmental monitoring-the study defines refined requirements for cores in terms of undisturbed property， cleanliness， representativeness， and information correlation. Furthermore， it proposes core technical solutions including stratified differentiated core recovery rate standards， disturbance and cleanliness level classification systems， a "target-stratum-technique" adaptation matrix， and a full-lifecycle information traceability mechanism， thereby establishing a comprehensive and highly targeted normative framework with strong operability. The research outcomes provide technical support for improving the quality of urban geological coring in Beijing and serve as a reference for other megacities in China undertaking similar work， which are of great significance for consolidating the geological guarantee foundation for urban safe development.
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GUO Guangding, JIN Xin, WU Xinkai, LI Zhijun
2026,53(4):113-125, DOI: 10.12143/j.ztgc.2026.04.012
Abstract:
To address the technical challenges of severe dust hazards， difficulties in coal fines transport， and insufficient anti-contamination and compressive resistance of existing foam drilling fluid systems during air screw drilling in broken-soft coal seams， a foam drilling fluid system suitable for this working condition was developed. Through performance screening， the foaming agent DF-1， foam stabilizer MZ-1， anti-contamination agent MPS， and compression-resistant agent HS plant gum were identified as the core components. Single-factor experiments yielded the preliminary optimal concentrations of these components as 0.9%， 0.3%， 0.4%， and 0.3%， respectively. Subsequently， a four-factor， three-level Box-Behnken experimental model was constructed based on response surface methodology （RSM） to investigate the interactive effects of the components on foam volume and half-life， and formulation optimization was performed considering the circulation time requirements of field drilling. The results indicate that the significance order of factors affecting foam volume is MZ-1>HS plant gum>MPS>DF-1， and that affecting half-life is MZ-1>MPS>HS plant gum>DF-1. Considering the foam circulation requirements of field drilling， the optimal formulation achieving a target half-life of 40 min is determined as 1.1% DF-1+0.1% MZ-1+0.5% MPS+0.3% HS plant gum. Validation experiments demonstrate that this formulation produces a foam volume of 510 mL and a half-life of 46 min， with significantly improved anti-contamination and compressive resistance， FCI reduction rate of 28.91% and compression ratio of 73.33%， effectively meeting the requirements for safe and efficient drilling in broken-soft coal seams. This study confirms that RSM can synergistically optimize multi-component foam systems， and the developed formulation exhibits excellent foaming， foam stability， anti-contamination， and compressive resistance properties， providing technical support for safe and efficient drilling in broken-soft coal seams.
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LIN Chengyuan, ZHANG Zhanrong, SUN Honglin, HU Ping
2026,53(4):126-133, DOI: 10.12143/j.ztgc.2026.04.013
Abstract:
To address the problems of low efficiency and information lag in conventional core drilling， as well as the limited classification accuracy of existing while-drilling identification models caused by the neglect of parameter multicollinearity and hyperparameter optimization， an intelligent while-drilling identification method for formation structure is proposed based on the fusion of principal component analysis （PCA）， particle swarm optimization （PSO）， and random forest （RF）. First， four features-feed pressure， rotational speed， torque， and pump pressure-that are highly correlated with formation structure are selected from multiple while-drilling parameters using Pearson correlation analysis. Second， PCA is applied to reduce the original four-dimensional features to three principal components with a cumulative contribution rate exceeding 95%， thereby eliminating multicollinearity among the features. Finally， the PSO algorithm is used to globally optimize the hyperparameters of the RF classifier. The model is constructed based on measured data and compared with various other algorithms. The results indicate that the PCA-PSO-RF fusion model achieves an F1-score of 0.964， with both precision and recall exceeding 96%， significantly outperforming the unoptimized RF model and mainstream gradient boosting algorithms. The validation accuracy on an independent borehole dataset is 84.8%， and the prediction accuracy for unlabeled data is 83%， with a misclassification rate of only 2% for intact rock sections， demonstrating the model''s robustness and generalization capability. This study achieves real-time， high-precision identification of fractured and intact rock sections， providing reliable technical support for intelligent drilling and geotechnical engineering investigation.
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ZHANG Hao, LI Zhijun, LI Fenglin, SONG Liyong, YUAN Changjin, FANG Xin, WANG Sheng
2026,53(4):134-144, DOI: 10.12143/j.ztgc.2026.04.014
Abstract:
To address technical challenges such as borehole wall instability and low core recovery in deep overburden drilling， this paper constructs two microbial drilling fluid systems suitable for wire-line coring-sodium carboxymethyl cellulose （CMC） and biopolymer （XC）-based systems—using Bacillus pasteurii as the core microorganism， based on microbially induced carbonate precipitation （MICP） technology and by comprehensively balancing microbial growth characteristics with drilling fluid rheological requirements. Engineering application tests were conducted in deep overburden coring for a major hydropower exploration project in western China， achieving a total footage of 258.75 m. Concurrently， the mechanism of wall stabilization and core protection of microbial drilling fluids was investigated through X-ray diffraction （XRD） and scanning electron microscope （SEM） analyses of core sample surfaces and interiors. The results indicate that a CMC dosage of 0.8% and an XC dosage of 0.3% ensure good microbial growth while meeting the rheological requirements for drilling fluid in the drilling process. The optimized formula is determined as： 0.8% CMC/0.3% XC + Bacillus pasteurii （OD600=0.8） + 0.5% NaCl + 2% urea + 2% tryptone. Both microbial drilling fluids exhibit excellent rheological properties and biological activity. Field applications demonstrated effective borehole wall stability maintenance， with core recovery rates exceeding 90%， enabling long-section open-hole drilling in deep overburden and significantly simplifying the borehole structure. The microorganisms in the drilling fluid induced calcium carbonate crystal formation （e.g.， vaterite， calcite） on core surfaces and around borehole walls. These crystals deposited on the surfaces of loose overburden particles and within pores， effectively cementing the loose particles to form a dense protective layer， thereby achieving wall stabilization and core protection. This study provides a novel solution for technical problems such as borehole wall instability and low core recovery in deep overburden core drilling， holding significant engineering application value for improving the quality of deep overburden drilling and exploration.
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GUO Qiang, WENG Wei, LU Tong, YANG Peng, ZHAO Zhitao, XU Junjun, ZHANG Jiefeng, CHEN Xiaohua
2026,53(4):145-153, DOI: 10.12143/j.ztgc.2026.04.015
Abstract:
To address the issue of low drilling efficiency in high-temperature hard rock formations during deep geothermal drilling， this paper investigates the structural optimization and hydraulic performance of turbine blades using a ?178 mm high-speed turbodrill as the research object. A mathematical model for the output characteristics of the turbodrill was established based on the moment of momentum theorem and the law of conservation of energy. The blade profile was designed using a quintic polynomial curve， and a degenerated twisted forming method was proposed to replace the traditional stretch forming process. Finite element fluid analysis was employed to compare the velocity and pressure field distributions of the blades before and after optimization， and an indoor bench test system was built to verify the optimization effect. The results indicate that the blades formed by the degenerated twisted method achieve an equal-width flow channel distribution， improve pressure field uniformity， and reduce vortex losses. The experimental results were consistent with the simulation trends， validating the effectiveness of the optimization method. At the rated speed， the output torque of the optimized single-stage turbine increased by 65.58%， the hydraulic efficiency improved from 67.92% to 76.89%， and the pressure drop decreased by 4.27%. This study provides a theoretical basis and technical support for improving deep geothermal drilling efficiency， reducing energy consumption， and extending the service life of drilling tools.
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ZANG Chenkun, GAO Mingshuai, WANG Yuzhe, LI Kuan, HE Lei, SONG Zhiliang, SUN Weina, SUN Junying
2026,53(4):154-162, DOI: 10.12143/j.ztgc.2026.04.016
Abstract:
To address the problems of traditional spindle core drilling rigs， such as high labor intensity， high safety risks， borehole instability caused by frequent rod pulling， and the inability to acquire drilling parameters in real time， this paper proposes a low-cost， high-performance digital upgrading and retrofitting scheme taking the XY-8 drilling rig as the research object. Following the principle of "main structure retention， function enhancement， and digital transformation"， the scheme adopts AC variable frequency motors to achieve stepless speed regulation for the rotary and hoisting systems， and reconstructs the braking system to a hydraulic disc brake system. A multi-mode cooperative feeding system is constructed， comprising small-motor automatic feeding， servo pump-controlled feeding， and non-powered disc brake feeding， which effectively solves the problem of limited stroke in conventional hydraulic cylinder feeding. Furthermore， a PLC-based electromechanical-hydraulic integrated control platform is developed to realize logical interlocking and closed-loop parameter control for all actuators. Prototype tests indicate that the speed control error of the retrofitted rig does not exceed ±1.5%， the weight on bit （WOB） control error is within ±5%， and the braking response time is shortened to 0.3 s. The energy consumption per unit footage and standby energy consumption are reduced by approximately 29% and 75%， respectively， while the retrofitting cost is about 25% lower than that of purchasing new equipment with equivalent performance. This study provides a replicable engineering path for the digital transformation of the massive stock of existing spindle drilling rigs， offering solid technical support for deep mineral exploration and the digitalization of geological equipment.
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WANG Wenbin, HONG Junzhan, LI Weiwu, SHAO Jun, LIU Jun, LI Huawei, WANG Huanhuan
2026,53(4):163-172, DOI: 10.12143/j.ztgc.2026.04.017
Abstract:
Hunan Province has huge potential of shale gas resources， however， controlled by the composite structure of the Yangtze Block and the Jiangnan Uplift Nappe Belt， well-developed folds and faults， extensive karst distribution， strong water sensitivity of shale formations， and frequent interbedding of hard and soft rocks are characterized in this area， leading to frequent engineering problems in deep drilling， such as lost circulation， borehole collapse， well deviation， difficult coring， poor cementing quality， and high well control risks， which severely restrict the exploration and development process. Based on data from more than 60 shale gas wells in Hunan Province， as well as the drilling practice and field tests of key wells from more than 30 shale gas wells implemented by the Hunan Coal Geological Exploration Institute， this paper systematically analyzes the engineering geological characteristics and key engineering challenges of five major gas-bearing formations in northwestern and central-southern Hunan， namely the Niutitang Formation of the Cambrian， the Longmaxi Formation of the Silurian， the Ceshui Formation of the Carboniferous， the Longtan Formation of the Permian， and the Shetianqiao Formation of the Devonian. To address the key engineering challenges of shale gas wells， a low-density expandable pressure-bearing lost circulation control technology has been developed （achieving one-time sealing of long sections with multiple loss zones）； an integrated anti-sloughing technology system of "strong inhibition+high-efficiency sealing" has been established （achieving a hot-rolling recovery rate of more than 99.6% and a 16 h expansion rate of no larger than 3.24%）； three new types of wire-line coring tools have been developed （increasing the core recovery rate from about 70% to over 90%）； a precise wellbore trajectory control technology combining PDC bit， single-bend screw motor and MWD/LWD has been developed； an integrated well control technology system of "near-balanced drilling-active throttling circulation-mud logging warning" has been established； and a complete set of cementing technologies featuring "safe casing running-high efficiency displacement-high toughness anti-channeling" has been formed （achieving a 100% high quality cementing rate）. Finally， a deep shale gas drilling construction technology system suitable for the complex geological conditions of Hunan Province has been developed， consisting of four-spud sectional drilling， graded drilling fluid maintenance， and whole-process quality control of cementing. This system has been successfully applied in more than 30 wells， providing important technical support for shale gas and other deep mineral exploration in complex geological areas of South China.
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2026,53(4):173-176, DOI: 10.12143/j.ztgc.2026.04.018
Abstract:
This biomimetic and adaptive drilling technology for mineral prospecting in complex strata is newly developed on the basis of existing mature geological drilling technologies. It adopts biomimetic and adaptive principles, takes the drilling bit as the core working component and targets complex formations, and features high safety and efficiency. This technology can provide a complete set of safe,reliable, efficient and proven drilling technical solutions for the new round of national strategic breakthroughs in mineral prospecting.
Volume 53,2026 Issue 4
超万米特深井钻探工艺与钻具专题
综述
钻探理论与方法
钻探技术与装备
工程实践与应用
技术快报
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Study on nano-composite cement plugging material for large channel of rock stratum
lijian, yangkang, gaoziquan, yanxiangfeng, wangsheng, liangchiming, tianxin, gaoqianyuan
Abstract:
The tectonic movement in the Qinghai-Tibet Plateau is active in China, and large channel voids are easily formed in the stratum. In the process of drilling construction, problems such as water inrush, leakage, and hole wall collapse are prone to occur. In view of the above problems, the basic properties of ordinary Portland cement and sulphoaluminate cement were systematically tested, and the suitable water reducing agent, early strength agent, nano-SiO2 and anti-dispersant agent were further screened to regulate the comprehensive performance of cement slurry, and a nano-composite cement-based plugging material was developed. The working and mechanical properties of the material were comprehensively evaluated by measuring the key indicators such as fluidity, pumpable period, setting time, compressive strength and dynamic water retention rate. Combined with scanning electron microscopy ( SEM ) observation, the internal mechanism of material strength improvement and dispersion resistance enhancement was analyzed. The results show that the developed nano-composite plugging material has good fluidity, controllable and short setting time, high early strength and excellent resistance to dynamic water erosion, which can meet the requirements of grouting plugging construction under the condition of large channel in rock strata, and provide reference for subsequent related research.
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