Pressure-preserved coring is a highly effective technique for preserving the structural integrity and fluid composition of reservoir cores. However, the lack of specialized testing methodologies hinders the precise evaluation of pressure-preserved core fidelity parameters. To address this challenge, a comprehensive study was conducted on the entire process of pressure-preserved transfer, cutting, and testing, culminating in the development of a pressure-preserved computed tomography (CT) scanning device. The critical technical challenges encountered during the development process were systematically analyzed through mechanical testing, CT scanning, and numerical simulations. Special emphasis was placed on material influences during testing, mechanical assembly interactions, and the accuracy of key parameter measurements in oil and gas exploration. Through comparative analysis and multitiered validation methods, polyether ether ketone (PEEK) material was ultimately selected as the key component of the coring device. The simulation and experimental results demonstrated that PEEK, with a maximum tensile strength of 104 MPa, sufficiently meets most core breakage thresholds of 93.942 MPa. Furthermore, CT scanning revealed a porosity measurement error of only 0.111%, confirming the reliability of the pressure-preserved CT test equipment. These findings offer valuable guidance for improving the precision of pressure-preserved core testing in deep oil and gas reservoirs.

Acquiring the accurate intrinsic mechanical parameters of deep in situ high-fidelity rock cores is fundamental for both maximizing the value of in situ condition-preserved coring technology and supporting the exploration and development of deep geological resources and energy. A key challenge, however, lies in conducting mechanical parameter measurements under in situ temperature and pressure conditions immediately after coring. To address the limitations of existing methods for determining the mechanical properties of high-fidelity cores, an innovative integrated point load testing method based on in situ condition-preserved coring is proposed. By integrating a point load testing system into the coring tool, mechanical tests are conducted directly on the core inside the device immediately after retrieval, thus preserving the deep in situ conditions and enabling true in situ acquisition of rock mechanical parameters. Through integrated theoretical analysis, numerical simulation, and experimental testing, a mechanical theoretical model for high-fidelity cores under point load conditions is established, and its stress distribution, deformation, and failure characteristics are preliminarily revealed. The validity of this model is verified through numerical simulations and laboratory experiments. Furthermore, a preliminary point load testing setup based on the in situ condition-preserved coring principle is developed and tested in laboratory and field trials, thereby preliminarily confirming the feasibility of the integrated approach. Therefore, this study provides technical support for the determination of the accurate intrinsic physicomechanical parameters of deep in situ rock masses and the evaluation of engineering rock mass behaviours.

The co-occurrence of marine gas hydrates, shallow gas, and deep oil and gas has been widely recognized, offering favorable conditions for integrated resource development. This study aims to explore the coupled production dynamics of shallow gas hydrates and underlying free gas to support the industrialization of marine natural gas hydrate resources. A productivity prediction model for the combined extraction of hydrate and underlying gas is developed, integrating multi-physics coupling mechanisms. Using logging data from two test wells in the Qiongdongnan Basin, a short-term physical model is constructed to simulate and predict production performance. Results show that: (1) The average wellhead gas production rate increases significantly with a linear relationship to the production pressure differential; (2) pressure propagation differs notably between hydrate and free gas layers, with a distinct low-temperature zone forming near the wellbore in the hydrate-bearing layer; (3) free gas migration results in a high-saturation gas zone near the hydrate-gas interface, and elevated pressure differentials can trigger secondary hydrate formation; and (4) during short-term testing, hydrate decomposition is limited, with most gas production sourced from the underlying gas layer. By adjusting production pressure or controlling wellbore temperature, hydrate decomposition and reformation can be balanced to optimize recovery efficiency. This study highlights a novel multi-gas co-production approach and provides a theoretical basis for sustainable deepwater hydrate development.

The moon harbors exceptionally abundant and strategically valuable spatial and material resources. As human lunar exploration gradually enters a new phase of development and utilization, lunar mining is transitioning from a strategic concept to tangible possibility. However, the unique properties of lunar regolith and the extreme complexity of the deep-space environment pose significant challenges to lunar mining. It has become imperative to explore and establish fundamental theories and key technologies for lunar mining that are applicable to the in-situ lunar environmental conditions. From the perspective of mining engineering, this paper systematically reviews the types and distribution characteristics of lunar mineral resources and compares the complexity and particularity of the lunar mining environment with terrestrial mining. Focusing on the key technical processes of “exploration-mining-utilization”involved in lunar mining, it elaborates on the main technical approaches and their current development status across five critical areas: in-situ lunar resource exploration and identification, mining and processing, conversion and utilization, lunar base construction, and in-situ energy support. The core mechanisms and adaptive challenges are also discussed. Based on this, addressing the key theoretical and future technological demands of lunar mining, the paper proposes a new paradigm for theoretical research in deep-space geomechanics, spanning from micro to macro scales, and identifies research directions for remote sensing prediction theories of lunar geomechanical properties at a global scale. Furthermore, it refines the conceptual framework and research directions for key technologies that require breakthroughs, such as deep in-situ coring technology with in-situ environmental conditions preservation for lunar prospecting, in-situ thermoelectric power generation technology on the moon, and lunar subsurface tunneling technology. Suggestions for theoretical construction and technical implementation are provided, which are expected to offer theoretical and technical guidance for future lunar mining engineering, in-situ resource development and utilization, lunar surface base construction, and underground space development.

Dry-hot rock (HDR) reservoir has attracted much attention because of its huge energy reserves. In order to ensure the long-term stable operation of engineering geothermal system, it is necessary to increase fractures in HDR by hydraulic fracturing to form effective flow channels. It is of great significance to study the coupling characteristics of seepage and stress in rock fracture for the safety and stability of engineering geothermal system. Effective stress coefficient can understand the hydraulic coupling characteristics of rock fractures from mechanism. However, the hydraulic coupling mechanism and effective stress law of proppant-supported fracture after hydraulic fracturing have not been well studied. In this work, we first introduce the asperities-voids-water pressure conceptual model of rough fracture, and initially determines the effect of water pressure (pore pressure) on fracture deformation. According to the definition of effective stress coefficient based on initial normal stiffness and maximum normal closure parameter, a new effective stress coefficient model of single rough fracture was proposed by taking the corresponding relationship between initial normal stiffness, fracture aperture and modulus as a bridge. Combined with cubic law, a fluid mechanics coupling model was further established to describe the relationship between hydraulic aperture of single fracture and effective normal stress. The validity of the model was verified by the comparative analysis of experimental data and modeling results. Then, the evolution law of effective stress coefficient under different normal stress and water pressure was analyzed. Results show that the new hydraulic coupling model can well describe the change process of aperture under normal stress, and the effective stress coefficient decreases with the increase of normal stress. Secondly, according to the definitions of fracture compressibility, the effect of proppant embedding effect on fracture volume was incorporated into compressibility model. On this basis, a fracture compressibility model considering proppant embedding was established. Then, the effective stress coefficient model of proppant-supported fracture was further proposed. That theoretical model was validated using hydro-mechanical coupling test data from granite fractures with different fractal characteristics. For a single rock fracture supported by proppant, the effective stress coefficient was also less than 1. And the effective stress coefficient of unsupported fracture was higher than that of proppant-supported. Furthermore, according to the control mechanism of effective stress on rock seepage, the application of effective stress coefficient in seepage modeling was discussed. Then, the seepage model considering dynamic effective stress coefficient was given, and the seepage laws of proppant-supported fractures and unsupported fractures were described respectively. Wherein, experimental data were in good agreement with the modeled flow rate evolution results during normal stress loading. In addition, proposed effective stress coefficient model can be incorporated into shear strength criterion of water-bearing rock to determine the stability of reservoirs, which will be important for production of geothermal wells.

To study the influence of drilling fluid invasion on the mechanical properties of gas hydrate-bearing sediments, acoustic-electricity-mechanics and displacement experimental devices were used to prepare gas hydrate-bearing sediment samples under different temperature, pressure, and saturation conditions, and undrained triaxial experiments were conducted under an effective confining pressure of 3 MPa. Under the condition of an invasion pressure difference of 2 MPa, the invasion process of water-based drilling fluid into gas hydrate-bearing sediment samples was simulated, and a post-invasion triaxial experiment was conducted. A numerical simulation of drilling fluid invasion was conducted based on experiments, and the evolution laws of parameters such as temperature, pressure, hydrate saturation, stress, strain, and expansion rate were analyzed. The results are shown as follows: (1) Before the invasion of drilling fluid, as the hydrate saturation increases, the gas hydrate-bearing sediment sample changes from strain hardening to strain softening, with a critical saturation range of 15–25

Abstract The prokaryotic ubiquitin-like protein (Pup) conjugation system (PPS), which is essential for Mycobacterium tuberculosis (Mtb) virulence but absent in humans, presents an attractive drug target. Here, we report the discovery of ARQ-501, a quinone-based, covalent, substrate-competitive inhibitor of the Pup ligase PafA. ARQ-501 exhibited potent anti-mycobacterial activity against Mtb under host-mimicking stress conditions and within macrophages. We further identified the catalase-peroxidase KatG, essential for activation of the frontline prodrug isoniazid (INH), as a pupylation substrate. ARQ-501 inhibits KatG pupylation, causing its accumulation and creating a selective synergy with INH. This ‘quantity over quality’ mechanism successfully rescued INH activation by the clinically prevalent KatG S315T mutant in enzymatic assays and enhanced INH efficacy against clinical S315T isolates to variable degrees. This work identifies a novel class of PafA inhibitors and a previously unrecognized role of pupylation in regulating KatG, offering a potential therapeutic avenue to combat drug-resistant tuberculosis.

This study addresses the unclear distribution characteristics of advance abutment pressure and mining-induced stress evolution during deep coal mining. A theoretical model for advance abutment pressure was established by coupling the statistical damage constitutive relationship of coal-rock mass with roof displacement and horizontal stress evolution. The model incorporates the Weibull distribution, Mises strength criterion, strain equivalence principle, and an attenuation parameter to characterize the progressive damage behavior of coal-rock mass under mining disturbance. Parametric sensitivity analysis was conducted to evaluate the effects of Young’s modulus, Poisson’s ratio, mining height, and roof displacement parameters on the peak value and location of advance abutment pressure. A three-dimensional numerical model of Working Face 8301 in Chenmanzhuang Coal Mine was developed using Rhino and FLAC3D to investigate mining-induced stress evolution. Results indicate that the stress field evolves from the initial in-situ state to a pattern characterized by “goaf unloading–roof adjustment–stress concentration ahead of the face”. The advance abutment pressure exhibits a typical trend of rapid increase, peak development, and decay. The theoretical model predicts a peak stress of 44.80 MPa at 16.17 m ahead of the coal wall, while numerical simulations yield peak stresses of 42–48 MPa at distances of 5–17.5 m. The close agreement between theoretical and numerical results demonstrates that the proposed model can reasonably characterize advance abutment pressure distribution and mining-induced stress evolution under deep mining conditions, providing a theoretical basis for support design, mining safety assessment, and disaster prevention in deep coal mines.

During underbalanced drilling (UBD), formation fluid influx can trigger supercritical phase transitions and dissolved gas liberation. This leads to systematic deviations in conventional single-phase flow or single-phase-transition models. Furthermore, classical solubility models fail to capture the non-equilibrium dissolution-liberation effects under rapidly changing pressure-temperature-flow conditions, reducing the accuracy of wellbore pressure prediction and the reliability of control, thereby increasing well control risks. To address this, this study develops a dynamic wellbore pressure model that couples a velocity-dependent Standing solubility model with dual-phase transitions (supercritical fluid and liberated dissolved gas). This model elucidates the dynamic impact of influx fluid type, non-equilibrium gas liberation, and phase transition processes on pressure fluctuations. Case studies demonstrate that non-equilibrium liberation causes a significant upward shift (approximately 751 meters) in the gas liberation point towards the wellhead and reduces gas holdup. Dissolved gas release reduces the annular hydrostatic pressure, while supercritical fluid expansion intensifies pressure oscillations. The coupling of these two mechanisms results in a bottom-hole pressure reduction of 1.72 MPa compared to single-phase-transition models, with pressure distribution exhibiting nonlinear characteristics. This research provides a quantitative analytical approach for pressure control and risk prevention during UBD in deep complex formations.

A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs. This temperature-preserved core chamber employs an innovative vacuum layer for temperature preservation and is compatible with a temperature-pressure preserved coring system. The design principles and key parameters of the temperature-preserved core chamber were determined through static analysis. Numerical simulations assessed the mechanical properties of 70, 85, and 100 MPa core chambers under conditions of 120 -150 degrees C. The results demonstrate that the temperature-preserved core chambers withstand the applied stresses without plastic deformation, and the vacuum layer maintains its integrity under these conditions. A 70 MPa class core chamber prototype was manufactured, and system integration tests were performed on a self-developed in-situ coring platform. The system demonstrated stable operation at 70 MPa for 120 min, with pressure fluctuations within 5%. Additionally, the integrated system operated without interference, enabling the successful extraction of cores with a 50 mm diameter. These findings provide valuable theoretical guidance and design recommendations for advancing oil and gas in-situ temperature-pressure preserved coring technologies in high-temperature and high-pressure environments. (c) 2025 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/

In the exploration and exploitation of methane hydrates, the influence of inorganic salt environments on hydrate behavior is particularly pronounced. This study employs experimental methodologies to evaluate the dissociation performance of hydrates in common inorganic salt solutions, coupled with molecular dynamics simulations to investigate the dissociation mechanisms under varying types of inorganic salts (MgCl2, CaCl2, KCl, and NaCl), mass concentrations, and multi-salt coexistence systems. The findings reveal that the efficacy of inorganic salt solutions in promoting hydrate dissociation follows the order: MgCl2 > CaCl2 > KCl > NaCl. The smaller ionic radius of Mg2+ and its stronger adsorption capacity for water molecules facilitate ion intrusion and the disruption of the hydrate's cage-like structure. In systems where multiple inorganic salts coexist, the higher potential energy and adsorption capacity result in the dissociation-promoting ability being predominantly determined by higher-valent metal cations. This research provides valuable macro and micro perspectives on the dissociation mechanisms of methane hydrates in inorganic salt environments, holding significant implications for the development of high-performance hydrate drilling fluid systems.

Pressure-preserved coring enables in situ encapsulation of deep coal samples at the borehole bottom. By effectively reducing gas desorption, it supports reliable reserve assessment. Achieving reliable pressure-preserved sealing within the confined space of drilling tools remains a critical technical challenge in the field. Focusing on the pressure controller, this study investigates three key aspects: configuration design, sealing interface behavior, and structural performance. The investigation employs both theoretical modeling and laboratory experiments. First, a geometric configuration design methodology was proposed for the pressure controller using intersecting contact and tapered sealing principles. This was followed by the creation of a spatial motion interference prediction model for the assemblies. Secondly, the contact behavior of intersecting sealing interfaces was studied; analysis of the failure mechanisms showed that the design achieves a pressure-preserved capacity of about 24 MPa. Finally, laboratory tests validated the sealing performance of the pressure controller. The tests confirmed that seal ring failure is characterized by high-pressure extrusion, which is caused by an increased sealing clearance. The research findings elucidate the sealing formation mechanism of the pressure controller, establishing a theoretical foundation for advancing pressure-preserved coring technologies in coalbed methane and gas hydrate exploration and development.

Pressure-preserved coring technologies are critical for deep-earth resource exploration but are con-strained by the inability to achieve multidirectional coring,restricting exploration range while escalating costs and environmental impacts.We developed a multidirectional pressure-preserved coring system based on magnetic control for deep-earth environments up to 5000 m.The system integrates a magnet-ically controlled method and key pressure-preserved components to ensure precise self-triggering and self-sealing.It is supported by geometric control equations for optimizing structural stability.Their struc-ture was verified and optimized through theoretical and numerical calculations to meet design objec-tives.To clarify the self-triggering mechanism in complex environments,a dynamic interference model was established,verifying stability during multidirectional coring.The prototype was fabricated,and functional tests confirmed that it met its design objectives.In a 300-meter-deep test inclined well,10 cor-ing operations were completed with a 100%pressure-preserved success rate,confirming the accuracy of the dynamic interference model analysis.Field trials in a 1970-meter-deep inclined petroleum well,rep-resentative of complex environments,demonstrated an in-situ pressure preservation efficiency of 92.18%at 22 MPa.This system innovatively expands the application scope of pressure-preserved coring,provid-ing technical support for efficient and sustainable deep resources exploration and mining.

The pressure-preserving controller is the key component of deep in situ pressure-preserving coring (IPP-Coring). With increasing drilling depth, the environmental temperature and pressure increase accordingly. However, due to the strength and sealing problems of pressure-preserving controllers, the coring pressure is generally lower than 70 MPa. Establishing a high-temperature and ultrahigh-pressure test system is highly important for improving the strength and sealing performance of pressure-preserving controllers. This paper introduces a high-temperature and ultrahigh-pressure test system for deep IPP-Coring controller performance analysis. The device includes six parts: an auxiliary air source system, a pressurization system, a temperature control system, a hydraulic system, a data acquisition and electrical control system, and an ultrahigh-pressure vessel. The test system can reconstruct a 150 °C and 200 MPa in situ environment and simulate and test the movement state of the corer and the stability of the pressure-preserving action trigger of the pressure-preserving controller in the deep IPP-Coring process. To verify the performance of this test system, saddle-shaped pressure-preserving controllers made of four different materials were subjected to pressure tests under normal-temperature and high-temperature conditions. The results showed that the ultimate pressure-bearing capability of the pressure-preserving controller greatly varied between normal-temperature and high-temperature conditions. The pressure-preserving ability and sealing performance of the pressure-preserving controller decreased significantly at high temperature, and the pressure-preserving controller exhibited significantly different sealing failure characteristics due to material differences. This study is important for progressing the extraction and evaluation of deep reservoir resources.

Gas content serves as a critical indicator for assessing the resource potential of deep coal mines and forecasting coal mine gas outburst risks. However, existing sampling technologies face challenges in maintaining the integrity of gas content within samples and are often constrained by estimation errors inherent in empirical formulas, which results in inaccurate gas content measurements. This study introduces a lightweight, in-situ pressure- and gas-preserved corer designed to collect coal samples under the pressure conditions at the sampling point, effectively preventing gas loss during transfer and significantly improving measurement accuracy. Additionally, a gas migration model for deep coal mines was developed to elucidate gas migration characteristics under pressure-preserved coring conditions. The model offers valuable insights for optimizing coring parameters, demonstrating that both minimizing the coring hole diameter and reducing the pressure difference between the coring-point pressure and the original pore pressure can effectively improve the precision of gas content measurements. Coring tests conducted at an experimental base validated the performance of the corer and its effectiveness in sample collection. Furthermore, successful horizontal coring tests conducted in an underground coal mine roadway demonstrated that the measured gas content using pressure-preserved coring was 34% higher than that obtained through open sampling methods.

The consolidation-creep behavior of deep-sea sediments is crucial for the stability of mining equipment but remains poorly understood in mining areas. This study investigates the surface sediments in the western Pacific Ocean deep-sea mining area, revealing their extreme properties (high water content, liquid limit, and void ratio) that make them more compressible than those in Nansha and Shanghai, while their relatively low organic matter content mitigates excessive deformation, reflecting the unique effects of the deep-sea sedimentary environment and guiding equipment settlement risk assessment, reflecting the unique effects of the sedimentary environment and guiding the assessment of equipment settlement risk. Deformation occurs in three stages: instantaneous compression, attenuation creep, and stable creep. The compression coefficient shows a nonlinear trend (first increasing, then decreasing) due to competition between particle aggregates fragmentation and compaction, a mechanism specific to these deep-sea sediments. The loading ratio has a significant impact on compression and secondary consolidation coefficients, with high ratios reducing the structural adjustment capacity. Microstructural analysis identifies lamellar honeycomb, skeleton, and flocculated structures, with pore distribution changes during consolidation-creep. A quantitative link between microstructural evolution and macroscopic deformation is established, which is rarely reported for such sediments. These findings deepen understanding of deformation mechanisms and guide optimization of mining equipment design and operation.

The pressure relief check valve plays a pivotal role in determining the oil and gas content during deep in-situ pressure-preserved coring. Prolonged exposure to high-pressure, high-solid-content fluids in deep wells can lead to mechanical erosion of the check valve, potentially causing severe failure and a loss of sealing integrity. To withstand the typical flow conditions in shale gas wells and on the basis of an in-depth understanding of deep fluid dynamics, a check valve was designed to operate at 70 MPa pressure and relieve pressure after coring. To mitigate erosion, a coupled Computational Fluid Dynamics-Discrete Element Method model was applied to simulate fluid flow dynamics and identify regions susceptible to erosion and wear in the valve body. The findings confirmed that the proposed check valve design meets the requirements for shale gas pressure-preserved coring and testing, with erosion mainly occurring in the constricted regions of the flow path. The erosion depth was found to increase with higher inlet flow rate and mass flow rates, demonstrating a sixfold increase as the inlet flow rate rises from 10 to 30 m/s. Non-spherical particles caused significantly more erosion than spherical ones, while the erosion depth decreased with larger particle sizes, showing a 33% reduction as particle size increased from 0.02 to 0.14 mm. To avoid sealing failures caused by prolonged erosion, the constricted flow channel was redesigned to accommodate an arc-shaped structure and appropriately widened. Simulations indicated that this structure can reduce peak pressure to 69% of the original value and minimize wall impacts. The maximum erosion depth decreased by 10%, indicating the improved durability and sealing of the redesigned check valve. These results underscore the enhanced check valve’s superior erosion resistance and sealing performance, highlighting its potential for future shale gas collection and testing and providing an effective strategy to enhance the reliability and longevity of check valves.

Pressure-preserving controllers (PPCs) are crucial components of in situ pressure-preserving coring (IPP-Coring) devices for deep oil and gas extraction, and their ultimate pressure-bearing (UPB) capability determines the upper limit of their ability to acquire oil and gas reserves. However, due to the UPB-capability and sealing challenges, the working pressure typically does not exceed 70 MPa. In this study, the optimal design of a PPC using a self-developed IPP-Coring test platform is presented, and its seal failure mechanism is revealed. Experimental results demonstrate that the designed saddle-shaped PPC achieves a minimal UPB-capability of 140 MPa, which is twice the highest value reported in literature. A numerical simulation method was developed to predict the UPB-capability of the PPC, and its reliability was validated in comparison with experimental results. The simulation results indicate that the sealing failure of the PPC is attributed to a progressive escalation in seal clearance between valve cover and seat, which causes an O-ring extrusion. Under ambient temperature and ultrahigh pressure, the critical threshold for seal clearance in PPC seal failure is approximately 0.2 mm. These results provide significant insights into enhancing deep resource acquisition capabilities.

Accurately evaluating the quality and scale of deep oil and gas reservoirs is the key to effectively exploring and developing deep oil and gas resources. Changes in temperature and pressure can cause significant variations in key reservoir quality parameters, such as porosity, permeability, and saturation, leading to distortions in oil and gas reserve assessments. To addresses the technical bottleneck of the existing pressure-preserved coring systems, which has a pressure-preserved capacity not exceed 70 MPa due to the limitations of small coring space, a complex coring environment, significant disturbance during the coring process, and the difficulty in controlling coring operations, a self-sealing control principle and method for pressure-preserved coring was proposed. The sealing structural parameters of the pressure-preserved controller (PPC) under high temperature (150 degrees C) were optimized through experiments and numerical simulations, the sealing failure mechanism was thoroughly revealed, and the pressure-preserved capacity of the PPC under high temperature was enhanced from 100 to 140 MPa. In addition, to achieve the temperature preservation of the core in the deep oil and gas environment, a temperature preservation system combining active and passive temperature preservation was designed and integrated into the deep oil and gas in-situ temperature pressure preserved (ITPP) coring system. Finally, the coring function and temperature pressure preserved capacity of the ITPP coring system were verified through field and laboratory tests. The results show that the developed ITPP coring system can successfully achieve the temperature pressure preserved function, and can sample oil and gas-bearing core samples with a diameter of 50 mm and a maximum length of 1000 mm from wells up to 5000 m. This study addresses the urgent need for reliable and effective pressure-preservation in deep oil and gas exploration. (c) 2025 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ncnd/4.0/).