The electric fields have regulating effects on the pore blockages of water-in-oil (W/O) emulsions during oil shale in-situ pyrolysis. This study systematically analyzes the coupled unblocking mechanisms of electric field on pore-blocking emulsions through multi-scale integration of macroscopic electric field concentration and microscopic molecular motion. Based on the reasonable assumption of the findings of pilot pyrolysis, finite element (FEM) simulations revealed that pore blockages induce parallel electric field concentration along pores during electric field in-situ pyrolysis, which acts on pore-blocking emulsions. Subsequent molecular dynamics (MD) simulations of pore/porewall-fluid systems under electric fields, integrated with gravity transformation experiments, enabled joint analysis of emulsion states in electro-gravitational coupled fields. It is found that electric fields enhance the binding energy between water and non-hydrophilic mineral surfaces, boosting the displacement efficiency of water to oil. The water chains induced by the electric fields produce anisotropic viscosity of the emulsions through ionic convection and altered molecular distribution-perpendicular to field increases and parallel decreases. This viscosity heterogeneity and molecule distribution can lead to temporary oil retention of the coalescing droplets during gravitational settlement, promoting partial transformation of W/O emulsions into low-viscosity oil-in-water (O/W) emulsions. The concentrated electric fields produce the above displacement-flow-transformation coupling "breakdown" effects at the blockages, with post-breakdown field redistribution to new blockages enabling continuous pore unblocking. The electric field unblocking effect proposed in this study can enhance pore connectivity to improve recovery efficiency. It provides theoretical support for optimizing in-situ pyrolysis technology to achieve efficient and low-carbon production enhancement.

Multi-wire arc additive manufacturing (MWAAM) has higher deposition efficiency and material utilization than traditional wire arc additive manufacturing (WAAM), but its droplet transition mode is more complex and sensitive, which affects not only the forming quality but also the metallurgical quality. Therefore, it is necessary and urgent to explore and optimize its process. In this study, the macroscopic component formation mechanism and microstructure influence mechanism of WAAM and MWAAM processes were studied, and TC11 titanium alloy was taken as the target alloy considering its huge application prospect in the aerospace field. In addition, the effects of different processes on the morphology, microstructure, phase composition, mechanical properties and wear properties of the deposited samples were systematically studied through the deposition experiments controlled by different heat source velocities. The results show that the thin-walled TC11 components deposited by MWAAM exhibit good mechanical properties and excellent wear resistance. This study is of great significance for the intelligent and industrialized development of MWWAM technology.

In hydrothermal system, the fault acting as the fluid pathway to assist extraction wells for extracting hydrothermal resources is being concerned. In this study, a coupled thermal-hydraulic- mechanical model of a fault-controlled hydrothermal system was established. The spatiotemporal evolution of the temperature-seepage field in thermal recovery system was revealed, and effects of fault physical characteristics, extraction parameters and well distance on thermal recovery performance were analyzed. The results show that, with the prolongation of extraction time (0-20 years), the thermal recovery performance of the fracture-controlled hydrothermal system is significantly better than conventional hydrothermal system. With the permeability of fault rocks transforms from isotropic to anisotropic, the production power of hydrothermal system increases. In the unbalanced extraction scheme, the production power decreases with the reduction of the extraction flow rate of the middle well. Three extraction schemes were studied, and the hydro- thermal system has a better thermal recovery performance when the scheme with a smaller imbalance coefficient. In addition, it is found that with the shortening of the distance between the extraction well and the recharge well, the production power decreases significantly.

Large piles of coal gangue pose significant environmental challenges, including water pollution, soil contamination, and air pollution. Therefore, there is an urgent need to explore sustainable and ecological methods for the effective utilization of coal gangue. In this study, a thermophilic bacterial strain, Bacillus aerius, was successfully isolated to enhance coal gangue solubilization. This bacterium facilitates the release of essential nutrients, including available potassium, available phosphorus, alkaline hydrolysis nitrogen, and humic-like substances from coal gangue. XRD, FTIR, SEM, and 3D fluorescence analyses revealed that Bacillus aerius adheres to the surface of coal gangue, promoting its biodegradation. Additionally, the bacterium was shown to produce extracellular enzymes and low-molecular-weight organic acids, particularly acetic acid, to enhance coal gangue solubilization. Pot experiments demonstrated that supplementing with Bacillus aerius and coal gangue significantly increased the seed germination rate and promoted the growth of alfalfa compared to the control. Overall, our findings suggest that Bacillus aerius can improve the utilization of coal gangue as a mineral fertilizer, offering a promising strategy for its sustainable and clean use.

Oil shale in-situ conversion has received considerable attention due to its potential for commercialization. However, most in-situ conversion technologies remain confined to theoretical studies and laboratory research. Topochemical heat technology (TSA), an in-situ conversion technology, heats oil shale under a nitrogen atmosphere and efficiently pyrolyzes it into shale oil and gas products in ambient air conditions. This study presents two in-situ field experiments conducted using TSA in Fuyu oil shale. It interprets the real-time qualitative and quantitative thermal expansion and asphaltene blockage effects under nitrogen and air atmospheres. The results showed that during heating nitrogen injection in technical step 2 (TS2), the estimated permeability decreased by 53.4%, from 2.53 to 1.18 mD, significantly affecting heat exchange efficiency. When injecting ambient air, the estimated permeability sharply increased from 1.18 to 7.83 mD, which is 5.63 times higher than during nitrogen heating, and then fluctuated between 0 and 7.83 mD. Additionally, several seepage channel blockages occurred in TS2 due to asphaltene precipitation. In this study, we explicitly illustrated the mechanism of thermal expansion and asphaltene blockage effects and solved these problems by adjusting injecting parameters. The findings provide a valuable reference for commercializing oil shale in-situ conversion.

The autothermic pyrolysis in-situ conversion process (ATS) has a considerable advantage in reducing the development costs of oil shale. However, the trigger mechanism of autothermic pyrolysis oxidation reaction in different fractured oil shale formations is not precise. This study conducts a one-dimensional residual carbon oxidation experiment on the oil shale sample, taking into account the overburden pressure. The trigger condition and parameters are determined through the energy analysis during residual carbon oxidation in the fractured oil shale. A trigger simulation model of autothermic pyrolysis oxidation reaction in different fractured oil shale formations is proposed and verified by the temperature field evolution. The results indicate that the heterogeneous oxidation reaction produces a high permeability channel in the oil shale formation, which can further improve the flow conductivity of the oil shale formation. The trigger threshold of the residual carbon oxidation reaction in the fractured oil shale formation was closely associated with the carbon residue concentration (> 2.59 x 104 mol/m(3)), oxygen content (>15 %), and gas crossflow between the fracture and matrix (0.56-0.78). This study has important theoretical guiding significance for triggering and controlling the ATS.

Multi-cluster temporary plugging and diverting fracturing (TPDF) is a key technique for enhancing reservoir stimulation in shale formations. However, existing models often overlook the interactions between temporary plugging agents and fracturing fluids, resulting in uncertainties in the initiation and propagation of multiple fractures. To address this, a physical simulation approach incorporating laser scanning and digital fracture reconstruction was developed to investigate the propagation characteristics of complex fractures under TPDF conditions. In addition, a three-dimensional discrete lattice model was proposed to simulate and control fracture propagation in TPDF operations. The effects of plugging ball quantity, plugging timing, and differential horizontal stress were systematically evaluated. Results demonstrate that TPDF effectively mitigates stress interference between fractures, thereby promoting more uniform fracture propagation and fluid distribution. An optimal number of plugging balls, approximately half the number of perforation clusters, was found to minimize fracture propagation imbalance. Moreover, the diversion effectiveness was highly sensitive to the timing of ball injection, with the optimal window occurring between one-half and two-thirds of the total pumping duration. Field applications in Jurassic continental shale oil wells in the Sichuan Basin, China, validated these findings. These insights offer practical guidance for optimizing TPDF design and execution in unconventional reservoirs.

With the ongoing development of oil and gas resources, low-permeability tight reservoirs have become a focal point of research and technological innovation. To effectively address the challenges associated with fracture fluid retention, this study investigates the role of CO2 in reservoir stimulation and productivity enhancement. The results reveal that liquid CO2 induces a rapid temperature reduction in shale samples during the initial phase of injection with a temperature decrease of 16.1 °C observed within the first 10 min. However, the cooling rate diminishes significantly in the later stages, with only a 0.8 °C decrease recorded over the subsequent 10 min which indicating a distinct endothermic effect. The high diffusivity and low viscosity of CO2 are key to its effectiveness in enhancing reservoir pressure and improving fracture conductivity. Additionally, the expansion-induced cooling effect of CO2 lowers wellbore temperatures, thereby lowering the viscosity of the fracturing fluid and improving its mobility. A stable pressure gradient provides the driving force for efficient fracture fluid recovery, which significantly boosting recovery efficiency and productivity. The results further indicate that at injection rates of 5000 m3/d, 10,000 m3/d, and 15,000 m3/d, the recovery volumes are 97%, 96%, and 88% higher than those achieved with water-based fracturing fluids, respectively. These findings demonstrate the significant advantages of CO2 injection in increasing reservoir pressure and promotes the flow of oil and gas at the well bottom. The promising application potential of CO2 in low-permeability tight reservoirs underscores its value as an innovative approach to reservoir stimulation and productivity optimization. This study provides the first comprehensive analysis of CO2's dual role in enhancing flowback efficiency through thermal, mechanical, and fluid dynamic interactions, offering a paradigm shift from conventional water-based fracturing.

Sealing is an important prerequisite for downhole heater work. This paper proposes a combination of soft and hard, and welding sealing programs, which were analysed using theoretical calculations, numerical simulation, and in-situ testing. The results show that stainless steel can meet the stuffing seal requirements. The first stuffing leads to compression and gradual reduction, while the second stuffing essentially does not deform. Stuffing deformation fills the gap in the sealing hole, creating a sealing layer. The compression rate is 0.43%, 8.45%, and 12.64%, indicating that the locking stress should be more than 2000 N. The temperature at the weld is heated by heat conduction and distributed in a concentric circle. Thermal stress will influence the 50 mm barrier, but the 100 mm boundary will be mostly unaffected. Actually, the thermal stress that destroys the weld seal may be reduced by adjusting the heater output or raising the gas injection rate. During beginning of the in-situ heat injection, the temperature of the heating rods rises simultaneously with the outlet temperature. Consequently, show opposite tendencies. The heat generated by the heating rods will cause the injected gas to be preheated in advance.

High-temperature thermal injection is a key step in extracting unconventional oil and gas. The study proposes an innovative application approach for downhole combustion heaters, which utilizes low calorific value gas as the heat source for in-situ combustion and heat injection mining. This paper employs numerical simulation methods to analyze the catalytic combustion processes of methane, hydrogen, and carbon monoxide, and yields quantitative data on exhaust gas temperature and conversion rates. The research reveals significant differences in the impact of different types of low calorific value gases on catalytic combustion. Hydrogen combustion is most sensitive to temperature changes. As the mole fraction of hydrogen increases from 2% to 10%, the exhaust gas temperature rises from 909.18 K to 919.51 K. Moreover, the limitation in the number of catalyst active sites is an important factor affecting catalytic combustion performance. The catalytic combustion of low calorific value gases composed of hydrogen and carbon monoxide results in a change of exhaust gas temperature ranging from 908.72 K to 913.11 K. The determination of the theoretical results provides a reference basis for the subsequent experimental development of low calorific value gas catalytic combustion heaters, and offers a new approach for energy conservation and emission reduction.

Reservoir stimulation for in-situ oil shale conversion employed hydraulic fracturing, as demonstrated in the Nong'an oil shale in-situ conversion project. This study examines the extent of reservoir stimulation and the associated changes in permeability. Hydraulic fracturing significantly increased the reservoir stimulation volume, raising the permeability in the stimulated area to 324.6 mD. Subsequent water replacement involved injecting lower-temperature nitrogen, which mitigated volume shrinkage and closed microfractures. However, this process reduced permeability by 80.54%, decreasing the seepage area to 2660.7 m3. The gas injection and mining process encompassed two stages: warming and cracking. The former aimed to enhance the drying of the formation in the stimulation area, restoring 22.87% of the permeability of the original area. The latter stage facilitated organic matter decomposition to release hydrocarbons, increasing the permeability of the reformed region to 704.842 mD. The reservoir-stimulated area can be categorized into cracking, high seepage, or low seepage zones, depending on the difficulty of injected gas flow and the extent of high-temperature influence.

This study involved the fabrication of defect-free Ti6Al4V/NiTi functional gradient materials (FGMs) using laser-directed energy deposition (LDED). The resulting Ti6Al4V/NiTi FGM showed a varied microstructure with different grain shapes and irregular eutectic structures. As the NiTi content increased, the number and shape of precipitates in various deposited layers underwent significant alterations due to phase transitions. Notably, employing thermodynamic principles, we proposed a discrete FGM strategy by selectively excluding certain composition ranges, resulting in a tensile strength increase of more than 46.3% compared to continuous FGMs. This study offers a promising approach for developing and optimizing additive manufacturing using heterogeneous structures.

In this study, a temperature optimization strategy for the Huadian oil shale autothermal pyrolysis in-situ conversion process (ATS) was first proposed by systematically investigating the reaction characteristics of various semi-cokes. As the pyrolysis temperature rised, the semi-coke's calorific value was found to undergo three different stages of increasing, decreasing, and flattening, peaking at around 330 degrees C. Additionally, the semi-cokes formed at different temperatures exhibited similar combustion characteristics, including combustion activation energy, combustion characteristic parameters, and product release characteristics. Due to the serious pore blockage caused by the substantial generation and the ignition coking of the bitumen, the reaction characteristics of semi-cokes were dramatically decreased at about 330 degrees C. Finally, the relationship between in-situ heat generation and demand at various stages of ATS process was discussed, and a reasonable strategy for the screening of temperature parameters was proposed. According to this strategy, the optimal control temperature for the preheating stage was determined at 350-370 degrees C and at Tact (defined in 4.3.2) for the retorting zone in the reaction stage. The results of this study provide a new perspective on the theoretical foundation of the ATS process and have crucial guiding implications for practical engineering applications.

The autothermic pyrolysis in-situ conversion process（ATS） consumes latent heat of residual organic matter after kerogen pyrolysis by oxidation reaction, and it has the advantages of low development cost and exploitation of deep oil shale resources. However, the heating mechanism and the characteristic of different reaction zones are still unclear. In this study, an ATS numerical simulation model was proposed for the development of oil shale, which considers the pyrolysis of kerogen, high-temperature oxidation,and low-temperature oxidation. Based on the above model, the mechanism of the ATS was analyzed and the effects of preheating temperature, O 2 content, and injection rate on recovery factor and energy efficiency were studied. The results showed that the ATS in the formation can be divided into five characteristic zones by evolution of the oil and O 2 distribution, and the solid organic matter, including residue zone, autothermic zone, pyrolysis zone, preheating zone, and original zone. Energy efficiency was much higher for the ATS than for the high-temperature nitrogen injection in-situ conversion process（HNICP）.There is a threshold value of the preheating temperature, the oil content, and the injection rate during the ATS, which is 400°C, 0.18, and 1100 m 3 /day, respectively, in this study.

The effects of preheating temperature and oxygen flow rate on the reaction behaviour and product yields and characteristics after the oxidative assisted pyrolysis (OP) of Huadian oil shale were systematically investigated in this paper. The results show two marked temperature boundaries in the OP reaction process, namely, the initiation temperature and the ignition temperature. First, an obvious initiation process could be found when the oil shale was preheated above a relatively lower temperature of 190 degrees C, which was considered to be the first boundary temperature of OP. Actually, the initiation was caused by the self-heating effect which could effectively enhance the pyrolysis of kerogen. Moreover, the self-heating effect could be strengthened by increasing the oxygen flow rate. However, an excessively high preheating temperature or oxygen flow rate may result in excessively high internal temperatures, which could exceed the ignition temperature of some organics, that is, the second boundary temperature of OP. Furthermore, the self-heating effect could improve the contents of heavy components, asphaltenes, and resins in the shale oil products at a suitable preheating temperature. Finally, a mechanism whereby the preheating temperature and oxygen flow rate influence the OP behaviour of oil shale was proposed.

A marginal gas injection method was previously proposed based on two-dimensional (2-D) homogeneous porous media, and the feasibility of isolating the oil shale pyrolysis zone from the surrounding hydrological environment had been demonstrated. The gas-water flow characteristics and dynamics during gas injection in 2-D porous media with a high-permeability zone (HPZ) were studied further based on the presence of a HPZ after fracturing oil shale reservoirs. A series of experiments were performed when the gas-injection point was located outside, at the boundary, or inside the HPZ (Case1-3). The HPZ enriched the injected gas, and in Cases 2 and 3, the gas inside the HPZ permeated to the low-permeability zone (LPZ) on both sides, forming two wing tributaries. However, in Case 1, water flowed into the HPZ in the opposite direction. In Cases 2 and 3, the direction of the local pressure gradient on both sides of the HPZ was completely opposite, indicating that the distribution of the pressure field was the direct cause of the gas-water flow characteristics. Therefore, the water-stopping effect of gas injection is primarily reflected in the HPZ. Additionally, the effect was best when the gas-injection point was set at the boundary or inside of the HPZ. These results were verified using reservoir-scale simulations and tests, in which the water yield decreased to ~ 100 kg/d. Subsequently, we recommended the sites of gas-injection wells for water stopping. All results are expected to provide strategies and theories for dealing with the adverse hydrological environment in large-scale oil shale in situ exploitation.

China's oil shale reserves are 739.1 billion tons and 45 per cent of which are in Songliao Basin. Therefore, a pilot project is conducted in Songliao Basin, aimed at technical preparation for commercial in-situ oil shale processes production. Because N2 is readily accessible and has no damage to the formation, the high-temperature nitrogen injection in-situ conversion process (HNICP) is the most basic convection heating technique, which is used in the pilot project. In this study, the Wellington reaction model is adjusted to describes the pyrolysis behavior and characteristics of shale in Songliao Basin, China. Based on the geological data and production date of the pilot project in Songliao Basin, a simulation model matching the production test scheme is established to investigate subsequent production performance and the evolution of reservoir physical properties for 550 days. Finally, the effect of injection temperature, total organic carbon (TOC), and enclosing area on the recovery factor is analyzed. The results show that the oil production rate can be divided into four stages for the HNICP of oil shale. In the third stage, prechar accumulation is very severe in the main fracture. However, the prechar accumulation relieves the heat short problem in the main fracture. The high temperature is beneficial to the production of oil, HC, and prechar. The formation plugging in the low TOC shale formation is more serious. Because of the spontaneous imbibition of oil in the formation away from the main fracture, the small enclosing area is beneficial to the production of oil.

Using numerical method to investigate the evolution of micro-structure in unsaturated soil is helpful to explain their physical mechanical. However, the evolution of micro-structure in unsaturated soil is not clear. For this reason, the capillary method is proposed to simulate compression test of unsaturated soil for analyzing soil-water interaction and evolution of pore spaces. In this research, an ideal micro-structure soil model of 540 μm×400 μm is established according to the shape and size of skeleton particles of loess. The capillary method is used to calculate the capillary water distribution and capillary force under different water content(5%, 10%, 18%), and the force then acts on the wetting surface among particles. The loading is applied to the soil sample. The compression test of unsaturated soil is simulated in this research. The simulation results show that the characteristics of compression curve are in good agreement with the experiment data, indicating that the numerical test can reflect the unsaturated soil deformation behavior under the condition of compress. Moreover, the saturation increases and matric suction decreases with the compression of the soil; the saturation increases most at high water content; the matric suction decreases least at middle water content; the deformation pattern is related with the moisture, namely, the pores are mainly shrunk at low water content while mainly disintegrated at high water content. The simulation results are a very useful supplement to laboratory test to explore the deformation mechanism of unsaturated soil.

患者 女,66岁,因左腕持续性疼痛伴活动受限5 d、加重3 d入院.5 d前无明显诱因左腕部出现持续性疼痛,3 d前不慎挫伤致疼痛加重.局部外固定制动、外敷及口服非甾体类药物后症状无明显缓解.既往无腕关节外伤史,无痛风、类风湿性关节炎及化脓性关节炎等病史.

Objective:To evaluate the clinical efficacy of trapeziectomy combined with modified abductor pollicis longus suspension arthroplasty for the treatment of the first carpometacarpal joint osteoarthritis.Methods:From November 2017 to April 2020, 7 patients with the first carpometacarpal joint osteoarthritis underwent trapeziectomy combined with modified abductor pollicis longus suspension arthroplasty. The thumb mobility, pain score, upper limb dysfunction score and the height of the first carpometacarpal joint were followed up at 1, 3 and 6 months after operation.Results:The patients were follow-up for 8 to 47 months, with an average of 28.6 months. The Kapandji score of thumb mobility was (4.67±2.40) before operation and (8.56±1.13) 3 months after operation. The VAS was (7.11±2.42) before operation and (1.44±0.88) at the last follow-up. The upper limb dysfunction score Quick-DASH score was (61.88±16.87) before operation and (24.49±14.08) at the last follow-up. The height of the first carpometacarpal joint was (8.66±0.70) mm before operation and (6.36±1.74) mm 3 months after operation. The level of proximal displacement of the first metacarpal bone at 3 months after operation was (27.19±17.40)%.Conclusion:The application of trapeziectomy combined with modified abductor pollicis longus suspension arthroplasty for the treatment of the first carpometacarpal joint osteoarthritis can alleviate thumb pain, improve thumb mobility and significantly improve upper limb function. It is an effective treatment method worthy of recommendation.