Weak cementation between natural gas hydrates and mud–sand seriously affects the solid-fluidized mining of natural gas hydrates. In this study, we analyze the debonding of natural gas hydrate sediment (NGHS) particle...Weak cementation between natural gas hydrates and mud–sand seriously affects the solid-fluidized mining of natural gas hydrates. In this study, we analyze the debonding of natural gas hydrate sediment (NGHS) particles by applying the principle of spiral-cyclone coupling separation. To achieve this, weakly cemented NGHS particle and mechanical models were established. In the flow field of the spiral-cyclone flow-coupling separator, the motion characteristics of the weakly cemented NGHS particles and the destruction process of the cementation bond were analyzed. The destruction of the bonds mainly occurred in the spiral channel, and the destruction efficiency of the bonds was mainly affected by the rotational speed. Collision analysis of the particles and walls showed that when the velocity is 10–16 m·s^(−1), the cementation bond can be broken. The greater the speed, the better the effect of the bond fracture. The breaking rate of the cementation bonds was 85.7%. This study is significant for improving the degumming efficiency in natural gas hydrate exploitation, improving the recovery efficiency of hydrates, and promoting the commercialization of hydrate solid fluidization exploitation.展开更多
The successful development of shale oil and gas reservoirs is the biggest technological revolution in the oil and gas industry.Its key technologies are horizontal well drilling and fracturing,which are based on unders...The successful development of shale oil and gas reservoirs is the biggest technological revolution in the oil and gas industry.Its key technologies are horizontal well drilling and fracturing,which are based on understanding the mechanical properties of reservoir rocks.Therefore,it is critical to obtain the reservoir mechanical parameters quickly,efficiently,and inexpensively.In this study,shale samples were collected from three basins in Southwest China,and the elastic modulus of shale in the indentation depth range of 0-5000 nm was obtained by nanoindentation experiments.Experimental results showed that different indentation depths had different physical characteristics.The shallower depths had the mechanical properties of single minerals,while the deeper depths had the mechanical properties of a multi-mineral composite.The difference between the two represented the cementation strength between the mineral particles.The error between the calculation results of the existing equivalent medium theoretical model and experimental data reached 324%.In this study,a weak cementation model was adopted,and three parameters obtained by nanoindentation experiments were considered:the soft component volume content,intergranular cementation strength,and mineral particle size.This solved the problem of assuming rather than calculating the values of some parameters in the existing model and realized the prediction of the macroscopic mechanical parameters of shale.The calculation error was reduced to less than 20%,and the test method and calculation model can be popularized and applied in engineering.展开更多
Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measur...Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measured at both the cone mid-face and the shoulder.The effects of penetrometer size and penetration rate were considered.The results of the study were presented as several updated soil behavior charts.In this reply,the issues raised during the discussion are addressed,including the geotechnical behavior and laboratory and in situ tests of weathered granite.The constructive feedback from the discussers not only enriches the research works of the studied soils but also enhances the understanding of weathering geomaterials.展开更多
The application of microbially induced carbonate precipitation(MICP)in clayey soils has attracted much attention,and many studies used clay as an additive to enhance microbial mineralization efficiency in sandy soils....The application of microbially induced carbonate precipitation(MICP)in clayey soils has attracted much attention,and many studies used clay as an additive to enhance microbial mineralization efficiency in sandy soils.Within the sand-clay-bacteria-calcite system,the property and content of clay play crucial roles in affecting bacterial growth and calcite formation.More important,bentonite is particularly sensitive to changes in the geochemical environment.In this study,the sand-bentonite mixtures were treated by biostimulated MICP,aiming to provide insights into the behavior of this system.The bacterial activity and cementation pattern at different bentonite contents were evaluated through a series of tests such as enrichment tests,unconfined compressive strength(UCS)tests,cementation content measurements,mercury intrusion porosimetry(MIP)tests,scanning electron microscopy(SEM)observations,and energy dispersive X-ray spectroscopy(EDS)analyses.The findings showed that the bentonite presence promoted the enrichment of indigenous ureolytic bacteria,with lower bentonite levels enhancing ureolytic activity.Macroscopic and microscopic characterization indicated that the bentonite-coating sand structure was more conducive to the formation of large-sized calcite crystals capable of cementing soil particles compared to sand-supported and bentonite-supported structures.Additionally,excessive calcium ions(Ca^(2+))concentrations in the cementitious solution would lead to predominant calcite deposition on soil particle surfaces,contributing minimally to strength improvement.展开更多
Various industrial waste binders(IWBs)are being recycled in soil stabilization to save cement consumption.However,the coupled effects brought out by combined IWBs on stabilized soils are still unclear.IWBs are categor...Various industrial waste binders(IWBs)are being recycled in soil stabilization to save cement consumption.However,the coupled effects brought out by combined IWBs on stabilized soils are still unclear.IWBs are categorized into two typical categories(IWB-A and IWB-B)referring to their chemical role in this study.The alkali-source effect,pore-filling effect and cementation damage effect by IWBs in soil stabilization are explored.A series of mechanical and microscopic tests is performed on stabilized clay with different proportions of IWB-A and IWB-B.Moreover,initial water contents and cement contents of cement-stabilized clay are varied to examine the evolution of coupled effect with void ratio and cementation level.The results indicate that the alkali-source effect strengthens the cementation bonds and increases the early strength by 0.5e1.3 times,whereas the pore-filling effect improves the microfabric especially for the specimen with a large void ratio.The alkali-source effect increases soil cohesion cu at the pre-yield stage,and the pore-filling effect increases frictional angle 4u at the post-yield stage.The cementation damage effect is remarkable at a low void ratio,which may result in many extruded pores among soil aggregates.The strength evolution with IWB proportions can be well stimulated by considering the coupled alkali-source effect,pore-filling effect and cementation damage effect.The optimal proportion of IWBs corresponds to an optimal combination of coupled effect.展开更多
In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack...In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process with a slurry pack cementation mixture composed of TiO2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH4Cl and albumen （egg white） as cohesive agent. The Ti-Al coating was fabricated on the surface of electro-deposited nickel layer on copper matrix followed by the slurry pack cementation process. The effects of slurry pack cementation temperature on the microstructures and wear resistance of Ti-Al coating were studied. The results show that the microstructure of the coating changed from NiAl＋Ni3（Ti,Al） to NiAl ＋Ni3（Ti,Al）＋Ni4Ti3 to Ni4Ti3＋NiAl, and to NiAl＋Ni3（Ti,Al）＋NiTi with slurry pack cementation temperature ranging from 800 ℃ to 950 ℃ in 12 h. The friction coefficient of Ti-Al coating decreased and the hardness increased with increasing the slurry pack cementation temperature. The minimum friction coefficient was 1/3 and the minimum hardness was 5 times larger than that of pure copper.展开更多
This article investigates the low-temperature formation of aluminide coatings on a Ni-base superalloy by pack cementation process. The pack cemented coatings characteristic of high density and homogeneity possess a tw...This article investigates the low-temperature formation of aluminide coatings on a Ni-base superalloy by pack cementation process. The pack cemented coatings characteristic of high density and homogeneity possess a two-layer structure. The top layer mainly consists of Al3Ni2 and Al3Ni,while the bottom layer of Al3Ni2. Great efforts are made to elucidate the effects of different experimental parameters on the microstructure and the constituent distribution of the coatings. The results show that all the parameters exclusive of the pack activator （NH4Cl） content produce effect on the coating thickness,but do not on the microstructure and the constituent distribution. The pack activator （NH4Cl） content affects neither the coating thickness nor structure and constituent distribution. The parabolic relationship between the coating thickness and the deposition time suggests that the process is diffusion-controlled. Furthermore,the article demonstrates a linear relationship between the coating thickness and the re-ciprocal deposition temperature.展开更多
In order to improve the corrosion resistance and increase the service lifetime of P110 steel during operation,four chromizing coatings were formed onto its surface with/without addition of rare earths via pack cementa...In order to improve the corrosion resistance and increase the service lifetime of P110 steel during operation,four chromizing coatings were formed onto its surface with/without addition of rare earths via pack cementation process.The surface morphologies and microstructures of the chromizing coatings were observed using scanning electron microscopy(SEM),and the phase constitutions were investigated by X-ray diffraction(XRD).Electrochemical corrosion behavior of the chromizing coatings in simulated oilfield ...展开更多
The halide-activated pack cementation method is utilized to deposit aluminide coat- ings on TiAl alloys. Emphasis is placed on the effect of alloying elements on the aluminizing behavior of TiAl alloy. The addition of...The halide-activated pack cementation method is utilized to deposit aluminide coat- ings on TiAl alloys. Emphasis is placed on the effect of alloying elements on the aluminizing behavior of TiAl alloy. The addition of a small amount of Nb or Cr in the TiAl improves significantly the aluminizing kinetics of TiAl alloys by increasing the solid-state division of Al through the formation of stable TiAl3 layer. The TiAl3 layer formed on the TiAl alloyed with Nb or Cr has better toughness than the TiAl3 formed on the non-alloyed TiAl. The reason for better toughness of the coating formed on TiAl is that partial TiAl3 with tetragonal structure was changed to high symmetry cubic L12 structure since Nb or Cr was dissolved into TiAl3. The TiAl3 layer formed on the TiAl alloyed with Nb or Cr has much better oxidation resistance than the TiAl3 layer formed on the non-alloyed TiAl. It is attributed to change in the crystal structure of TiAl3 from the brittle tetragonal DO22 to the ductile cubic L12 by addition of small amount of Nb or Cr.展开更多
The pack cementation was employed to produce rare earth modified chromium coatings on P110 steel aiming at improving its performance and increasing the usage lifetime during operation. The orthogonal array design （OA...The pack cementation was employed to produce rare earth modified chromium coatings on P110 steel aiming at improving its performance and increasing the usage lifetime during operation. The orthogonal array design （OAD） was applied to set experiments. Contents of NH4Cl, types of RE, contents of RE, test temperature and soaking time were the main factors, and each factor was endowed with four levels. While the range analysis and analysis of variance were used to investigate the results of OAD tests on thickness and wear resistance. The results indicated that for a promising coating with higher thickness value and excellent anti-wear property, the test temperature was the most significant process factor. The potential promising conditions for chromizing treatment were： adding 1% NH4Cl and 1% LaCl3, maintaining the test temperature at 1000 oC for 8 h. The results of verification showed that the coating formed under the optimal process parameter had a valid thickness of 28 μm and a reduction of 0.32 mg in wear resistance test.展开更多
The pack cementation was employed to improve the electrochemical corrosion resistance of 304 stainless steel via CeO2- Cr modified Ti coatings. Continuous coatings were formed on 304 stainless steel surface by this me...The pack cementation was employed to improve the electrochemical corrosion resistance of 304 stainless steel via CeO2- Cr modified Ti coatings. Continuous coatings were formed on 304 stainless steel surface by this method. A series of electrochemical experiments were carried out to investigate the corrosion resistance of 304 stainless steel, Ti coating and CeO2-Cr/Ti coatings. The sample surface was investigated by scanning electron microscopy （SEM）. The phases of sample surface were detected by X-ray diffraction （XRD）. It was concluded from all the outcomes that the Corrosion resistance of the samples could be sorted in the following sequence： CeO2-Cr/Ti coatings〉Ti coating〉304 stainless steel.展开更多
Objective It has long been controversial that whether authigenic chlorite coatings in sandstone reservoirs can prevent precipitation of siliceous cements. It is commonly believed that chlorite coatings （also called c...Objective It has long been controversial that whether authigenic chlorite coatings in sandstone reservoirs can prevent precipitation of siliceous cements. It is commonly believed that chlorite coatings （also called chlorite films, chlorite linings, or chlorite rims） may prevent quartz overgrowth, and thus help the preservation of original pores in sandstone reservoirs. Recently, however, this assumption has been challenged by reservoir geologists. This dispute cannot be solved by mere analysis of thin sections, nor by chemical equations and diagenesis analysis. The main objective of the present contribution is to shed light on this problem on the basis of sandstone samples from the Permian Shanxi and Shihezi Formations in the eastern part of the Sulige gas field, Ordos Basin in central China.展开更多
In order to obtain a high-performance surface on P110 steel that can meet the requirements in oil/gas field environment, the chromium coatings were fabricated by pack cementation. The chromium coatings differed in wit...In order to obtain a high-performance surface on P110 steel that can meet the requirements in oil/gas field environment, the chromium coatings were fabricated by pack cementation. The chromium coatings differed in with/without the addition of La2O3. Scanning electron microscope （SEM）, energy dispersive X-ray spectrometer （EDS）, X-ray diffractometer （XRD） and microhardness tester were employed to investigate the surface morphologies, surface element distributions, microstructures, phase constitutions and microhardness of the coatings. Friction-wear tests of the P110 steel substrate and the coatings were conducted in air at ambient temperature and humidity. The results show that ＇uniform and continuous coatings are formed on P110 steel regardless of adding La2O3 or not. The chromium coatings consist of Cr23C6, Cr7C3, and （Cr, Fe）7C3. The La2O3-added chromium coating is more beneficial in terms of surface morphology, microstructure, thickness and microharduess as compared with the coating without adding La2O3. Chromizing treatment significantly improves the surface hardness and wear resistance of the P110 steel. The wear resistance of the tested samples can be sorted in the following sequence： La2O3-coating 〉 no RE-coating 〉bare P110 steel.展开更多
The study of clastic rock failure evolution under true triaxial stress is an important research topic;however,it is rarely studied systematically due to the limitation of monitoring technology.In this study,true triax...The study of clastic rock failure evolution under true triaxial stress is an important research topic;however,it is rarely studied systematically due to the limitation of monitoring technology.In this study,true triaxial compression tests were conducted on clastic rock specimens to investigate the effect of cementation and intermediate principal stress(s2)on the failure mechanism.The complete stressestrain curves were obtained,while the acoustic emission(AE)was monitored to indirectly evaluate the evo-lution of tensile and shear cracks,and crack evolution under true triaxial compression was imaged in real time by a high-speed camera.The results showed that the deformation and failure characteristics of clastic rock were closely related to the cementation type and intermediate principal stress.On the basis of the distribution characteristics of the ratio of rise time to amplitude(RA)and the average frequency(AF)of AE signals,tensile cracks of the contact cementation specimen propagated preferentially.Meanwhile,the enhancement of specimen cementation promoted the evolution of shear cracks,and the increase inσ_(2)promoted the evolution of tensile cracks.Moreover,the mesoscale cracking mechanism of clastic rock caused by cementation andσ_(2)under true triaxial compression was analyzed.The failure patterns of clastic rock under true triaxial compression were divided into three modes:structure-induced,structure-stress-induced and stress-induced failures.This study confirms the feasibility of high-speed camera technology in true triaxial testing,and has important implications for elucidating the disaster mechanism of deep tunnels in weak rocks.展开更多
The resistivity experimental measurements of core samples drilled from low permeability reservoirs of Ordos Basin, Northwest China, illustrate that the cementation factors are not agminate, but vary from 1.335 to 1.74...The resistivity experimental measurements of core samples drilled from low permeability reservoirs of Ordos Basin, Northwest China, illustrate that the cementation factors are not agminate, but vary from 1.335 to 1.749. This leads to a challenge for the estimation of water and hydrocarbon sa- turation. Based on the analysis of Purcell equation and assumption that rock resistivity is determined by the parallel connection of numerous capillary resistances, a theoretical expression of cementation factor in terms of porosity and permeability is established. Then, cementation factor can be calculated if the parameters of porosity and permeability are determined. In the field application, porosity can be easily obtained by conventional logs. However, it is a tough challenge to estimate permeability due to the strong heterogeneity of low permeability reservoirs. Thus, the Schlumberger Doll Research （SDR） model derived from NMR logs has been proposed to estimate permeability. Based on the analysis of the theoretical expressions of cementation factor and SDR model, a novel cementation factor prediction model, which is relevant to porosity and logarithmic mean of NMR T2 spectrum （T21m）, is derived. The advantage of this model is that all the input information can be acquired from NMR logs accurately. In order to confirm the credibility of the novel model, the resistivity and corresponding laboratory NMR measurements of 27 core samples are conducted. The credibility of the model is confirmed by compar- ing the predicted cementation factors with the core analyzed results. The absolute errors for all core samples are lower than 0.071. Once this model is extended to field application, the accuracy of water and hydrocarbon saturation estimation will be significantly improved.展开更多
Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum par...Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum parameters.Cyclic voltammetry and linear sweep voltammetry were applied to investigating the reaction mechanism of electrically enhanced cementation of cadmium on a zinc plate.The optimum parameters were a temperature of 35℃,a cathode-to-anode area ratio of 1:2,an anode current density of 15 A/m2,an ultrasonic frequency of 40 kHz a reaction time of 6 h and an ultrasonic power of 100 W.The extraction rate was 99.21%,and the production of byproduct“floating sponge cadmium”was inhibited.The analysis of the cyclic voltammetry and linear sweep voltammetry diagrams showed that ultrasonic waves can promote and accelerate the replacement reaction,decrease the voltage requirement of the electrically enhanced replacement reaction,and change the reaction steps.In addition,increasing the temperature and ultrasonic power can promote and accelerate electrically enhanced replacement reactions and decrease the electric potential requirement.展开更多
A multi-component diffusion coating has been developed to protect Mo-based alloys from high temperature environmental attack. Aluminum addition was made during the coating process to improve the oxidation resistance b...A multi-component diffusion coating has been developed to protect Mo-based alloys from high temperature environmental attack. Aluminum addition was made during the coating process to improve the oxidation resistance by developing hexagonal Mo(Si, Al)2 through the development of the halide activated pack cementation coating process on pure Mo substrate. The results show that Mo(Si, Al)2 formed as a main phase on the surface and a little amount of Mo5Si3 also formed. The total thickness of coating is tens ofμm at 1373K. During the cyclic oxidation test at high temperature(at about 1323K in air), mullite (3Al2O3.2SiO2) and some SiO2 formed. The addition of Al is beneficial for MoSi2 coating and the Al-doped coating exhibited only a small weight gain and protected the Mo substrate, while the MoSi2 coating without Al suffered a significant weight loss, indicating a loss of volatile MoO3 after cycles.展开更多
Turbidite sandstones have become increasingly significant in hydrocarbon exploration.Carbonate cementation occur commonly in turbidite reservoirs developing within the Paleocene lacustrine basins,Northeastern China.Th...Turbidite sandstones have become increasingly significant in hydrocarbon exploration.Carbonate cementation occur commonly in turbidite reservoirs developing within the Paleocene lacustrine basins,Northeastern China.This study utilizes core data,thin section data and production data to investigate the interaction between the carbonate cementation and hydrocarbon charge within turbidite reservoirs in the Niuzhuang Sub-sag of the Dongying Sag,Bohai Bay Basin,East China.The results reveal that the carbonate cementation is mainly developed at the top and bottom of the turbidite sandbodies,and even forms carbonate cement shells.Three stages of hydrocarbon accumulation are identified based on fluid inclusion analysis:stage I(27.5–24.6 Ma),stage II(14.0–5.0 Ma),and stage III(5.0–0 Ma).The interaction between the carbonate cementation and hydrocarbon charge has significant controls on the formation of a turbidite reservoir.The temporal relations and intensity relations between the two factors should be considered significantly.Moreover,hydrocarbon charge during the early stage can inhibit the carbonate cementation,favoring the hydrocarbon accumulation in turbidite reservoirs.Many deep-lacustrine turbidite sandbodies surrounded by source rocks with abnormal high pressure,are also favorable for hydrocarbon accumulation.These results suggest that some deeply buried turbidite sandbodies with similar geological settings have high potential for hydrocarbon exploration.展开更多
The carburizing process is the enrichment of the depth of low carbon steels with carbon. It leads to samples with a combination of high surface hardness and high core toughness and to an impact strength that is requir...The carburizing process is the enrichment of the depth of low carbon steels with carbon. It leads to samples with a combination of high surface hardness and high core toughness and to an impact strength that is required for many engineering parts. The material studied is a low carbon steel. The carbon content is little in this type of steel （wc = 0.2 ~）. The calculation of case depth is very important for cementation steels that are hardened in the carburi- zing process. The effective case depth is defined as the perpendicular distance from the surface to a place at which the hardness is HV 550. Nowadays, a great number of studies have been carried out on the simulation of effective case depth, but no studies have been conducted to determine the numerical relation between the total case depth on one hand and the carburizing time and the effective case depth on the other hand. The steel specimens were subjected to graphite powder. Then, they were heat treated at 925 ~C for about 3, 5, 8 and 12 h, respectively. Then, these parts were quenched in oil. To determine the effective case depth, the micr0hardness test was performed on the cross-section of specimens. Plotting the case depth vs carburizing time, the required conditions for obtaining the specified case depth were determined. Also, the comparison between the case depths in numerical solution and the actual position in pack carburizing was performed.展开更多
Because of the cementation inherited from the parent rock,weathered granitic soil is usually susceptible to disturbance,which poses considerable challenges for laboratory characterization.The cone penetration test wit...Because of the cementation inherited from the parent rock,weathered granitic soil is usually susceptible to disturbance,which poses considerable challenges for laboratory characterization.The cone penetration test with pore pressure measurements has long been known for its reliability in site investigations and stratigraphic profiling.However,although extensive piezocone test results and experience are available for sedimentary soil,similar advances are yet to be made for weathered granitic soil.Moreover,the experience from sedimentary soil may not be directly applicable to weathered profiles because of the essentially different natures of the two types of geomaterials.This study performs seismic piezocone tests in a weathered granitic profile comprising residual granitic soil,completely weathered granite,and highly weathered granite.Pore pressure is measured at both the cone mid-face and the shoulder,and the effects of penetrometer size and penetration rate are considered.A series of updated soil behavior type charts is proposed to interpret the test results,thereby allowing the effect of weathering to be evaluated.This paper offers an important extension to the sparse data on the in situ responses of weathered materials.展开更多
基金funded by the State Key Laboratory of Natural Gas Hydrate of China(2022-KFJJ-SHW)the National Key Research and Development Program of China(2021YFC2800903)+2 种基金the National Natural Science Foundation of China(52004235)the National Natural Science Foundation General Program of China(52374011)the Miaozi Engineering Cultivation Project of Sichuan Science and Technology Department of China(MZG20230127).
文摘Weak cementation between natural gas hydrates and mud–sand seriously affects the solid-fluidized mining of natural gas hydrates. In this study, we analyze the debonding of natural gas hydrate sediment (NGHS) particles by applying the principle of spiral-cyclone coupling separation. To achieve this, weakly cemented NGHS particle and mechanical models were established. In the flow field of the spiral-cyclone flow-coupling separator, the motion characteristics of the weakly cemented NGHS particles and the destruction process of the cementation bond were analyzed. The destruction of the bonds mainly occurred in the spiral channel, and the destruction efficiency of the bonds was mainly affected by the rotational speed. Collision analysis of the particles and walls showed that when the velocity is 10–16 m·s^(−1), the cementation bond can be broken. The greater the speed, the better the effect of the bond fracture. The breaking rate of the cementation bonds was 85.7%. This study is significant for improving the degumming efficiency in natural gas hydrate exploitation, improving the recovery efficiency of hydrates, and promoting the commercialization of hydrate solid fluidization exploitation.
基金supported by the Key R&D Program Project of Xinjiang Province(2024B01013)the National Key Research and Development Program of China(2022YFE0129800).
文摘The successful development of shale oil and gas reservoirs is the biggest technological revolution in the oil and gas industry.Its key technologies are horizontal well drilling and fracturing,which are based on understanding the mechanical properties of reservoir rocks.Therefore,it is critical to obtain the reservoir mechanical parameters quickly,efficiently,and inexpensively.In this study,shale samples were collected from three basins in Southwest China,and the elastic modulus of shale in the indentation depth range of 0-5000 nm was obtained by nanoindentation experiments.Experimental results showed that different indentation depths had different physical characteristics.The shallower depths had the mechanical properties of single minerals,while the deeper depths had the mechanical properties of a multi-mineral composite.The difference between the two represented the cementation strength between the mineral particles.The error between the calculation results of the existing equivalent medium theoretical model and experimental data reached 324%.In this study,a weak cementation model was adopted,and three parameters obtained by nanoindentation experiments were considered:the soft component volume content,intergranular cementation strength,and mineral particle size.This solved the problem of assuming rather than calculating the values of some parameters in the existing model and realized the prediction of the macroscopic mechanical parameters of shale.The calculation error was reduced to less than 20%,and the test method and calculation model can be popularized and applied in engineering.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42307212 and 42177148)the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME-JBGS2403)。
文摘Recently,Danziger et al.(2024)published a discussion on our paper(Zhang et al.,2023).In the discussed paper,seismic piezocone tests were conducted to characterize a granitic weathering profile.Pore pressure was measured at both the cone mid-face and the shoulder.The effects of penetrometer size and penetration rate were considered.The results of the study were presented as several updated soil behavior charts.In this reply,the issues raised during the discussion are addressed,including the geotechnical behavior and laboratory and in situ tests of weathered granite.The constructive feedback from the discussers not only enriches the research works of the studied soils but also enhances the understanding of weathering geomaterials.
基金supported by the Key R&D Program Social Development Project of Jiangsu Province(Grant No.BE2023800)the Natural Science Foundation of China(Grant No.42377166)the National Key R&D Program of China(Grant No.2023YFC3709600)。
文摘The application of microbially induced carbonate precipitation(MICP)in clayey soils has attracted much attention,and many studies used clay as an additive to enhance microbial mineralization efficiency in sandy soils.Within the sand-clay-bacteria-calcite system,the property and content of clay play crucial roles in affecting bacterial growth and calcite formation.More important,bentonite is particularly sensitive to changes in the geochemical environment.In this study,the sand-bentonite mixtures were treated by biostimulated MICP,aiming to provide insights into the behavior of this system.The bacterial activity and cementation pattern at different bentonite contents were evaluated through a series of tests such as enrichment tests,unconfined compressive strength(UCS)tests,cementation content measurements,mercury intrusion porosimetry(MIP)tests,scanning electron microscopy(SEM)observations,and energy dispersive X-ray spectroscopy(EDS)analyses.The findings showed that the bentonite presence promoted the enrichment of indigenous ureolytic bacteria,with lower bentonite levels enhancing ureolytic activity.Macroscopic and microscopic characterization indicated that the bentonite-coating sand structure was more conducive to the formation of large-sized calcite crystals capable of cementing soil particles compared to sand-supported and bentonite-supported structures.Additionally,excessive calcium ions(Ca^(2+))concentrations in the cementitious solution would lead to predominant calcite deposition on soil particle surfaces,contributing minimally to strength improvement.
基金supported by the National Natural Science Foundation of China(Grant No.52378330)National Key R&D Program of China(Grant No.2015BAB07B06)Scientific Research Foundation of Graduate School of Southeast University(Grant No.YBPY2162).
文摘Various industrial waste binders(IWBs)are being recycled in soil stabilization to save cement consumption.However,the coupled effects brought out by combined IWBs on stabilized soils are still unclear.IWBs are categorized into two typical categories(IWB-A and IWB-B)referring to their chemical role in this study.The alkali-source effect,pore-filling effect and cementation damage effect by IWBs in soil stabilization are explored.A series of mechanical and microscopic tests is performed on stabilized clay with different proportions of IWB-A and IWB-B.Moreover,initial water contents and cement contents of cement-stabilized clay are varied to examine the evolution of coupled effect with void ratio and cementation level.The results indicate that the alkali-source effect strengthens the cementation bonds and increases the early strength by 0.5e1.3 times,whereas the pore-filling effect improves the microfabric especially for the specimen with a large void ratio.The alkali-source effect increases soil cohesion cu at the pre-yield stage,and the pore-filling effect increases frictional angle 4u at the post-yield stage.The cementation damage effect is remarkable at a low void ratio,which may result in many extruded pores among soil aggregates.The strength evolution with IWB proportions can be well stimulated by considering the coupled alkali-source effect,pore-filling effect and cementation damage effect.The optimal proportion of IWBs corresponds to an optimal combination of coupled effect.
基金Projects(YKJ201203,CKJB201205)supported by the Nanjing Institute of Technology,China
文摘In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process with a slurry pack cementation mixture composed of TiO2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH4Cl and albumen （egg white） as cohesive agent. The Ti-Al coating was fabricated on the surface of electro-deposited nickel layer on copper matrix followed by the slurry pack cementation process. The effects of slurry pack cementation temperature on the microstructures and wear resistance of Ti-Al coating were studied. The results show that the microstructure of the coating changed from NiAl＋Ni3（Ti,Al） to NiAl ＋Ni3（Ti,Al）＋Ni4Ti3 to Ni4Ti3＋NiAl, and to NiAl＋Ni3（Ti,Al）＋NiTi with slurry pack cementation temperature ranging from 800 ℃ to 950 ℃ in 12 h. The friction coefficient of Ti-Al coating decreased and the hardness increased with increasing the slurry pack cementation temperature. The minimum friction coefficient was 1/3 and the minimum hardness was 5 times larger than that of pure copper.
文摘This article investigates the low-temperature formation of aluminide coatings on a Ni-base superalloy by pack cementation process. The pack cemented coatings characteristic of high density and homogeneity possess a two-layer structure. The top layer mainly consists of Al3Ni2 and Al3Ni,while the bottom layer of Al3Ni2. Great efforts are made to elucidate the effects of different experimental parameters on the microstructure and the constituent distribution of the coatings. The results show that all the parameters exclusive of the pack activator （NH4Cl） content produce effect on the coating thickness,but do not on the microstructure and the constituent distribution. The pack activator （NH4Cl） content affects neither the coating thickness nor structure and constituent distribution. The parabolic relationship between the coating thickness and the deposition time suggests that the process is diffusion-controlled. Furthermore,the article demonstrates a linear relationship between the coating thickness and the re-ciprocal deposition temperature.
基金supported by the Science and Technology Programs for Research and Development of Shaanxi Province (2008K01-31)
文摘In order to improve the corrosion resistance and increase the service lifetime of P110 steel during operation,four chromizing coatings were formed onto its surface with/without addition of rare earths via pack cementation process.The surface morphologies and microstructures of the chromizing coatings were observed using scanning electron microscopy(SEM),and the phase constitutions were investigated by X-ray diffraction(XRD).Electrochemical corrosion behavior of the chromizing coatings in simulated oilfield ...
基金The National Natural Science Foundation of ChinaThe Korea Science and Engineering Foundation
文摘The halide-activated pack cementation method is utilized to deposit aluminide coat- ings on TiAl alloys. Emphasis is placed on the effect of alloying elements on the aluminizing behavior of TiAl alloy. The addition of a small amount of Nb or Cr in the TiAl improves significantly the aluminizing kinetics of TiAl alloys by increasing the solid-state division of Al through the formation of stable TiAl3 layer. The TiAl3 layer formed on the TiAl alloyed with Nb or Cr has better toughness than the TiAl3 formed on the non-alloyed TiAl. The reason for better toughness of the coating formed on TiAl is that partial TiAl3 with tetragonal structure was changed to high symmetry cubic L12 structure since Nb or Cr was dissolved into TiAl3. The TiAl3 layer formed on the TiAl alloyed with Nb or Cr has much better oxidation resistance than the TiAl3 layer formed on the non-alloyed TiAl. It is attributed to change in the crystal structure of TiAl3 from the brittle tetragonal DO22 to the ductile cubic L12 by addition of small amount of Nb or Cr.
基金supported by the Science and Technology Program for Research and Development of Shaanxi Province (2008K01-31)
文摘The pack cementation was employed to produce rare earth modified chromium coatings on P110 steel aiming at improving its performance and increasing the usage lifetime during operation. The orthogonal array design （OAD） was applied to set experiments. Contents of NH4Cl, types of RE, contents of RE, test temperature and soaking time were the main factors, and each factor was endowed with four levels. While the range analysis and analysis of variance were used to investigate the results of OAD tests on thickness and wear resistance. The results indicated that for a promising coating with higher thickness value and excellent anti-wear property, the test temperature was the most significant process factor. The potential promising conditions for chromizing treatment were： adding 1% NH4Cl and 1% LaCl3, maintaining the test temperature at 1000 oC for 8 h. The results of verification showed that the coating formed under the optimal process parameter had a valid thickness of 28 μm and a reduction of 0.32 mg in wear resistance test.
基金Project supported by Shanxi Province Programs for Science and Technology Development(20110321051)Shanxi Province Natural Science Foundation(2013021013-5,2012011021-3)
文摘The pack cementation was employed to improve the electrochemical corrosion resistance of 304 stainless steel via CeO2- Cr modified Ti coatings. Continuous coatings were formed on 304 stainless steel surface by this method. A series of electrochemical experiments were carried out to investigate the corrosion resistance of 304 stainless steel, Ti coating and CeO2-Cr/Ti coatings. The sample surface was investigated by scanning electron microscopy （SEM）. The phases of sample surface were detected by X-ray diffraction （XRD）. It was concluded from all the outcomes that the Corrosion resistance of the samples could be sorted in the following sequence： CeO2-Cr/Ti coatings〉Ti coating〉304 stainless steel.
基金supported by the National Natural Science Foundation of China(grant No.41402120)Shandong University of Science and Technology Research Fund(grant No.2015TDJH101)
文摘Objective It has long been controversial that whether authigenic chlorite coatings in sandstone reservoirs can prevent precipitation of siliceous cements. It is commonly believed that chlorite coatings （also called chlorite films, chlorite linings, or chlorite rims） may prevent quartz overgrowth, and thus help the preservation of original pores in sandstone reservoirs. Recently, however, this assumption has been challenged by reservoir geologists. This dispute cannot be solved by mere analysis of thin sections, nor by chemical equations and diagenesis analysis. The main objective of the present contribution is to shed light on this problem on the basis of sandstone samples from the Permian Shanxi and Shihezi Formations in the eastern part of the Sulige gas field, Ordos Basin in central China.
基金Project(2007CB607603) supported by the National Basic Research Program of China
文摘In order to obtain a high-performance surface on P110 steel that can meet the requirements in oil/gas field environment, the chromium coatings were fabricated by pack cementation. The chromium coatings differed in with/without the addition of La2O3. Scanning electron microscope （SEM）, energy dispersive X-ray spectrometer （EDS）, X-ray diffractometer （XRD） and microhardness tester were employed to investigate the surface morphologies, surface element distributions, microstructures, phase constitutions and microhardness of the coatings. Friction-wear tests of the P110 steel substrate and the coatings were conducted in air at ambient temperature and humidity. The results show that ＇uniform and continuous coatings are formed on P110 steel regardless of adding La2O3 or not. The chromium coatings consist of Cr23C6, Cr7C3, and （Cr, Fe）7C3. The La2O3-added chromium coating is more beneficial in terms of surface morphology, microstructure, thickness and microharduess as compared with the coating without adding La2O3. Chromizing treatment significantly improves the surface hardness and wear resistance of the P110 steel. The wear resistance of the tested samples can be sorted in the following sequence： La2O3-coating 〉 no RE-coating 〉bare P110 steel.
基金financial support from the 111 Project(Grant No.B17009)the Liaoning Revitalization Talents Program(Grant No.XLYCYSZX1902).
文摘The study of clastic rock failure evolution under true triaxial stress is an important research topic;however,it is rarely studied systematically due to the limitation of monitoring technology.In this study,true triaxial compression tests were conducted on clastic rock specimens to investigate the effect of cementation and intermediate principal stress(s2)on the failure mechanism.The complete stressestrain curves were obtained,while the acoustic emission(AE)was monitored to indirectly evaluate the evo-lution of tensile and shear cracks,and crack evolution under true triaxial compression was imaged in real time by a high-speed camera.The results showed that the deformation and failure characteristics of clastic rock were closely related to the cementation type and intermediate principal stress.On the basis of the distribution characteristics of the ratio of rise time to amplitude(RA)and the average frequency(AF)of AE signals,tensile cracks of the contact cementation specimen propagated preferentially.Meanwhile,the enhancement of specimen cementation promoted the evolution of shear cracks,and the increase inσ_(2)promoted the evolution of tensile cracks.Moreover,the mesoscale cracking mechanism of clastic rock caused by cementation andσ_(2)under true triaxial compression was analyzed.The failure patterns of clastic rock under true triaxial compression were divided into three modes:structure-induced,structure-stress-induced and stress-induced failures.This study confirms the feasibility of high-speed camera technology in true triaxial testing,and has important implications for elucidating the disaster mechanism of deep tunnels in weak rocks.
基金supported by the Major National Oil&Gas Specific Project of China(No.2011ZX05044)
文摘The resistivity experimental measurements of core samples drilled from low permeability reservoirs of Ordos Basin, Northwest China, illustrate that the cementation factors are not agminate, but vary from 1.335 to 1.749. This leads to a challenge for the estimation of water and hydrocarbon sa- turation. Based on the analysis of Purcell equation and assumption that rock resistivity is determined by the parallel connection of numerous capillary resistances, a theoretical expression of cementation factor in terms of porosity and permeability is established. Then, cementation factor can be calculated if the parameters of porosity and permeability are determined. In the field application, porosity can be easily obtained by conventional logs. However, it is a tough challenge to estimate permeability due to the strong heterogeneity of low permeability reservoirs. Thus, the Schlumberger Doll Research （SDR） model derived from NMR logs has been proposed to estimate permeability. Based on the analysis of the theoretical expressions of cementation factor and SDR model, a novel cementation factor prediction model, which is relevant to porosity and logarithmic mean of NMR T2 spectrum （T21m）, is derived. The advantage of this model is that all the input information can be acquired from NMR logs accurately. In order to confirm the credibility of the novel model, the resistivity and corresponding laboratory NMR measurements of 27 core samples are conducted. The credibility of the model is confirmed by compar- ing the predicted cementation factors with the core analyzed results. The absolute errors for all core samples are lower than 0.071. Once this model is extended to field application, the accuracy of water and hydrocarbon saturation estimation will be significantly improved.
基金Project (51574294) supported by the National Natural Science Foundation of ChinaProject (2018zzts447) supported by the Fundamental Research Funds for the Central Universities of Central South University, China
文摘Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum parameters.Cyclic voltammetry and linear sweep voltammetry were applied to investigating the reaction mechanism of electrically enhanced cementation of cadmium on a zinc plate.The optimum parameters were a temperature of 35℃,a cathode-to-anode area ratio of 1:2,an anode current density of 15 A/m2,an ultrasonic frequency of 40 kHz a reaction time of 6 h and an ultrasonic power of 100 W.The extraction rate was 99.21%,and the production of byproduct“floating sponge cadmium”was inhibited.The analysis of the cyclic voltammetry and linear sweep voltammetry diagrams showed that ultrasonic waves can promote and accelerate the replacement reaction,decrease the voltage requirement of the electrically enhanced replacement reaction,and change the reaction steps.In addition,increasing the temperature and ultrasonic power can promote and accelerate electrically enhanced replacement reactions and decrease the electric potential requirement.
文摘A multi-component diffusion coating has been developed to protect Mo-based alloys from high temperature environmental attack. Aluminum addition was made during the coating process to improve the oxidation resistance by developing hexagonal Mo(Si, Al)2 through the development of the halide activated pack cementation coating process on pure Mo substrate. The results show that Mo(Si, Al)2 formed as a main phase on the surface and a little amount of Mo5Si3 also formed. The total thickness of coating is tens ofμm at 1373K. During the cyclic oxidation test at high temperature(at about 1323K in air), mullite (3Al2O3.2SiO2) and some SiO2 formed. The addition of Al is beneficial for MoSi2 coating and the Al-doped coating exhibited only a small weight gain and protected the Mo substrate, while the MoSi2 coating without Al suffered a significant weight loss, indicating a loss of volatile MoO3 after cycles.
基金supported by the Open Fund(Grant No.PLC20190101)of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technologythe National Natural Science Foundation of China(Grant No.41703060)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.20CX02118A)the Opening Fund of Key Laboratory of Deep Oil&Gas,the Major Scientific and Technological Innovation Project of Shandong Province(Grant Nos.2017CXGC1602,2017CXGC1608)the Innovation Project of Postgraduate in Shandong University of Science and Technology(Grant No.SDKDYC190211)。
文摘Turbidite sandstones have become increasingly significant in hydrocarbon exploration.Carbonate cementation occur commonly in turbidite reservoirs developing within the Paleocene lacustrine basins,Northeastern China.This study utilizes core data,thin section data and production data to investigate the interaction between the carbonate cementation and hydrocarbon charge within turbidite reservoirs in the Niuzhuang Sub-sag of the Dongying Sag,Bohai Bay Basin,East China.The results reveal that the carbonate cementation is mainly developed at the top and bottom of the turbidite sandbodies,and even forms carbonate cement shells.Three stages of hydrocarbon accumulation are identified based on fluid inclusion analysis:stage I(27.5–24.6 Ma),stage II(14.0–5.0 Ma),and stage III(5.0–0 Ma).The interaction between the carbonate cementation and hydrocarbon charge has significant controls on the formation of a turbidite reservoir.The temporal relations and intensity relations between the two factors should be considered significantly.Moreover,hydrocarbon charge during the early stage can inhibit the carbonate cementation,favoring the hydrocarbon accumulation in turbidite reservoirs.Many deep-lacustrine turbidite sandbodies surrounded by source rocks with abnormal high pressure,are also favorable for hydrocarbon accumulation.These results suggest that some deeply buried turbidite sandbodies with similar geological settings have high potential for hydrocarbon exploration.
文摘The carburizing process is the enrichment of the depth of low carbon steels with carbon. It leads to samples with a combination of high surface hardness and high core toughness and to an impact strength that is required for many engineering parts. The material studied is a low carbon steel. The carbon content is little in this type of steel （wc = 0.2 ~）. The calculation of case depth is very important for cementation steels that are hardened in the carburi- zing process. The effective case depth is defined as the perpendicular distance from the surface to a place at which the hardness is HV 550. Nowadays, a great number of studies have been carried out on the simulation of effective case depth, but no studies have been conducted to determine the numerical relation between the total case depth on one hand and the carburizing time and the effective case depth on the other hand. The steel specimens were subjected to graphite powder. Then, they were heat treated at 925 ~C for about 3, 5, 8 and 12 h, respectively. Then, these parts were quenched in oil. To determine the effective case depth, the micr0hardness test was performed on the cross-section of specimens. Plotting the case depth vs carburizing time, the required conditions for obtaining the specified case depth were determined. Also, the comparison between the case depths in numerical solution and the actual position in pack carburizing was performed.
基金This paper was financially supported by the National Natural Science Foundation of China(Grant No.41972285)the Youth Innovation Promotion Association CAS(Grant No.2018363)Key R&D projects of Hubei Province,China(Grant No.2021BAA186).
文摘Because of the cementation inherited from the parent rock,weathered granitic soil is usually susceptible to disturbance,which poses considerable challenges for laboratory characterization.The cone penetration test with pore pressure measurements has long been known for its reliability in site investigations and stratigraphic profiling.However,although extensive piezocone test results and experience are available for sedimentary soil,similar advances are yet to be made for weathered granitic soil.Moreover,the experience from sedimentary soil may not be directly applicable to weathered profiles because of the essentially different natures of the two types of geomaterials.This study performs seismic piezocone tests in a weathered granitic profile comprising residual granitic soil,completely weathered granite,and highly weathered granite.Pore pressure is measured at both the cone mid-face and the shoulder,and the effects of penetrometer size and penetration rate are considered.A series of updated soil behavior type charts is proposed to interpret the test results,thereby allowing the effect of weathering to be evaluated.This paper offers an important extension to the sparse data on the in situ responses of weathered materials.
