Using cemented rockfill to replace coal pillars offers an effective solution for reducing solid waste while ensuring the safety of gob-side entries.However,achieving the balance among low cost,high waste recycling rat...Using cemented rockfill to replace coal pillars offers an effective solution for reducing solid waste while ensuring the safety of gob-side entries.However,achieving the balance among low cost,high waste recycling rates,and adequate strength remains a significant challenge for cemented rockfill.This study used a composite alkali activator to activate gangue cemented rockfill.The compressive strength,scanning electron microscopy,energy dispersive spectrometer,mercury intrusion porosimetry,X-ray diffraction,and thermogra-vimetric tests were carried out to investigate the effect of the composite alkali activator proportion on the compressive strength,micro-structure,and composition of the cemented rockfill.The calcium silicate hydrate(C–S–H)molecular model of cemented rockfill was con-structed to explore the fracture evolution of the nucleated molecular structure under tension.The results show that compressive strength initially increased and then decreased with the activator proportion,the optimal activator proportion of 1:2 resulted in a 31.25%increase in strength at 3 d.This reasonable activator proportion strengthens the pozzolanic effect of gangue,and consumes more calcium hydroxide to inhibit its agglomeration,ultimately achieving the densification of microstructure.The activator proportion inevitably substitutes calcium ions with sodium ions in the C–S–H molecular model.The 12%substitution of calcium ions increases the adhesion between silicon chain layers,which is beneficial to the interlayer stress transfer.This work proposes a method for preparing low-cost cemented rockfill from al-kali-activated gangue,which can be used for solid waste recycling and reducing cement consumption to achieve low-carbon goals.展开更多
Microcrack growth during progressive compressive failure in brittle rocks strongly influences the safety of deep underground engineering.The external shear stressτxy on brittle rocks greatly affects microcrack growth...Microcrack growth during progressive compressive failure in brittle rocks strongly influences the safety of deep underground engineering.The external shear stressτxy on brittle rocks greatly affects microcrack growth and progressive failure.However,the theoretical mechanism of the growth direction evolution of the newly generated wing crack during progressive failure has rarely been studied.A novel analytical method is proposed to evaluate the shear stress effect on the progressive compressive failure and microcrack growth direction in brittle rocks.This model consists of the wing crack growth model under the principal compressive stresses,the direction correlation of the general stress,the principal stress and the initial microcrack inclination,and the relationship between the wing crack length and strain.The shear stress effect on the relationship between y-direction stress and wing crack growth and the relationship between y-direction stress and y-direction strain are analyzed.The shear stress effect on the wing crack growth direction during the progressive compressive failure is determined.The initial crack angle effect on the y-direction peak stress and the wing crack growth direction during the progressive compressive failure considering shear stress is also discussed.A crucial conclusion is that the direction of wing crack growth has a U-shaped variation with the growth of the wing crack.The rationality of the analytical results is verified by an experiment and from numerical results.The study results provide theoretical support for the evaluation of the safety and stability of surrounding rocks in deep underground engineering.展开更多
Liquid hydrogen has attracted much attention due to its high energy storage density and suitability for long-distance transportation.An efficient hydrogen liquefaction process is the key to obtaining liquid hydrogen.I...Liquid hydrogen has attracted much attention due to its high energy storage density and suitability for long-distance transportation.An efficient hydrogen liquefaction process is the key to obtaining liquid hydrogen.In an effort to determine the parameter optimization of the hydrogen liquefaction process,this paper employed process simulation software Aspen HYSYS to simulate the hydrogen liquefaction process.By establishing a dynamic model of the unit module,this study carried out dynamic simulation optimization based on the steady-state process and process parameters of the hydrogen liquefaction process and analyzed the dynamic characteristics of the process.Based on the pressure drop characteristic experiment,an equation for the pressure drop in the heat exchanger was proposed.The heat transfer of hydrogen conversion was simulated and analyzed,and its accuracy was verified by comparison with the literature.The dynamic simulation of a plate-fin heat exchanger was carried out by coupling heat transfer simulation and the pressure drop experiment.The results show that the increase in inlet temperature(5℃and 10℃)leads to an increase in specific energy consumption(0.65%and 1.29%,respectively)and a decrease in hydrogen liquefaction rate(0.63%and 2.88%,respectively).When the inlet pressure decreases by 28.57%,the hydrogen temperature of the whole liquefaction process decreases and the specific energy consumption increases by 52.94%.The research results are of great significance for improving the operating efficiency of the refrigeration cycle and guiding the actual liquid hydrogen production.展开更多
Carbon capture and storage(CCS)remains one of the most feasible techniques for the control of Greenhouse gas emission levels.However,there will always be risks attached to the subsurface injection of CO_(2).These coul...Carbon capture and storage(CCS)remains one of the most feasible techniques for the control of Greenhouse gas emission levels.However,there will always be risks attached to the subsurface injection of CO_(2).These could be in the form of leakages from the injection wellbore due to completion failure;escape of the injected CO_(2)to neighboring aquifers due to the heterogeneous or fractured nature of the storage site;or seepage at the surface due to inadequacy of the sealing cap rock.While all these may occur,the most cost-effective and timely way to reduce the risk of leakages is by plugging the pathways.This is done using either traditional Cementous materials or more augmented sealants like organic gels and resins.A lot of studies in the literature have described this collection of materials within the context of CO_(2)conformance control.So also,there are reviews on the classification and description of these chemicals.This review provides a more systemic evaluation of these classes of chemicals.This is by providing critical analyses of how external factors like CO_(2),pH,brine salinity and hardness,rock mineralogy,pressure,temperature,and injectivity could affect the performance of different sealants that can be utilized.Based on these assessments,best practices for the application of the sealants,both at the testing stage in the laboratory and the pilot stage and field deployment,are suggested.展开更多
Many new and developed oilfields are confined to carbonate reservoirs with a complex void space structure.In this study,the behavior of carbonates as a function of decreased reservoir pressure was examined.The study w...Many new and developed oilfields are confined to carbonate reservoirs with a complex void space structure.In this study,the behavior of carbonates as a function of decreased reservoir pressure was examined.The study was based on actual production data from wells rather than just on model data or results from computational experiments.Well-test data(170 well tests)and laboratory core samples(45 samples)results were used in the analysis.The problem of reservoir deformation has been compre-hensively addressed at the micro and macro levels.The effect of reservoir permeability throughout the entire reservoir volume on reservoir pressure was determined.With a decline in reservoir pressure,the permeability of fractures and pores in carbonates decreases.The deformation coefficients,which char-acterize the actual rate of decrease in permeability with decreasing reservoir pressure,were also calculated.The deformation coefficients and data from core studies using μ-CT and SEM were compared.Based on micro-CT data,the effective diameters of the voids were calculated to be 93μm,109μm,and 140μm for the Vinnikovskoe,Sofinskoe,and Sukharev fields,respectively.Based on μ-CT and SEM data,the predominant geometric shapes of the voids were assessed.The deformation coefficient of voids was found to depend on their size and geometric shape.The study's findings revealed deformation co-efficients of 0.172,0.205,and 0.748 for the Vinnikovskoe,Sofinskoe,and Sukharev fields,respectively.Maximum deformation coefficients are typical for large voids with a predominant slot-like shape.However,even with the predominance of primary spherical voids in carbonates,the permeability of voids decreases with decreasing reservoir pressure.展开更多
Nowadays,the development of effective bioplastics aims to combine traditional plastics’functionality with environmentally friendly properties.The most effective and durable modern bioplastics are made from the edible...Nowadays,the development of effective bioplastics aims to combine traditional plastics’functionality with environmentally friendly properties.The most effective and durable modern bioplastics are made from the edible part of crops.This forces bioplastics to competewith food production because the crops that produce bioplastics can also be used for human nutrition.That is why the article’s main focus is on creating bioplastics using renewable,non-food raw materials(cellulose,lignin,etc.).Eco-friendly composites based on a renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch,and poly(lactic acid)with reed and hemp waste as a filler.The physic-chemical features of the structure and surface,as well as the technological characteristics of reed and hemp waste as the organic fillers for renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch,and poly(lactic acid),were studied.Theeffect of the fractional composition analysis,morphology,and nature of reed and hempwaste on the quality of the design of eco-friendly biodegradable composites and their ability to disperse in the matrix of renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch and poly(lactic acid)was carried out.The influence of different content and morphology of reed and hemp waste on the composite characteristics was investigated.It is shown that the most optimal direction for obtaining strong eco-friendly biodegradable composites based on a renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch,and poly(lactic acid)is associated with the use of waste reed stalks,with its optimal content at the level of 50 wt.%.展开更多
This study investigates the shear mechanical responses and debonding failure mechanisms of anchoring systems comprising three anisotropic media and two anisotropic interfaces under controlled boundary conditions of co...This study investigates the shear mechanical responses and debonding failure mechanisms of anchoring systems comprising three anisotropic media and two anisotropic interfaces under controlled boundary conditions of constant normal load(F_(s)),constant normal stiffness(K),and shear rate(v).A systematic analysis of shear mechanical properties,the evolution of maximum principal strain field,and damage characteristics along shear failure surface is presented.Results from direct shear tests demonstrate that initial shear slip diminishes with increasing F_(s)and K,attributed to the normal constraint strengthening effect,while an increase in v enhances initial shear slip due to attenuated deformation coordination and stress transfer.As F_(s)increases from 7.5 to 120 kN,K from 0 to 12 MPa/mm,and v from 0.1 to 2 mm/min,the peak shear load increases by 210.32%and 80.16%with rising F_(s)and K,respectively,while decreases by 38.57%with increasing v.Correspondingly,the shear modulus exhibits,respectively,a 135.29%and 177.06%increase with rising F_(s)and K,and a 37.03%decrease with larger v.Initial shear dilation is identified as marking the formation of shear failure surface along anisotropic interfaces,resulting from the combined shear actions at the resin bolt interface,where resin undergoes shear by bolt surface protrusions,and the resin-rock interface,where mutual shear occurs between resin and rock.With increasing F_(s)and K and decreasing v,the location of the shear failure surface shifts from the resin-rock interface to the resin-bolt interface,accompanied by a transition in failure mode from tensile rupture of resin to shear off at the resin surface.展开更多
Oleic acid （denoted as OA） surface-capped lanthanum-doped titanium dioxide composite nanoparticles, abbreviated as OA/La-TiO2, were prepared via sol-gel method in association with surface modification by oleic acid....Oleic acid （denoted as OA） surface-capped lanthanum-doped titanium dioxide composite nanoparticles, abbreviated as OA/La-TiO2, were prepared via sol-gel method in association with surface modification by oleic acid. The microstructure of as-prepared OA/La-TiO2 was characterized by means of X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrometry, and their thermal stability was evaluated by thermogravimetry and differential scanning calorimetry. Moreover, the tribological properties of OA/La-TiO2 as lubricant additives in rapeseed oil were evaluated with a four-ball friction and wear tester. The morphology as well as elemental composition and chemical characteristics of worn steel surfaces was investigated by scanning electron microscopy, energy dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. Results showed that as-prepared OA/La-TiO2 particles were of spherical shape and had an average diameter of 20 nm. In the meantime, OA/La-TiO2 particles doped with 1.5% （molar ratio; the same hereafter） and 2.5% of lanthanum could markedly improve the anti-wear and friction-reducing capacities of rapeseed oil. This is attributed to the formation of a complex boundary lubrication film mainly composed of the oxides of iron, titanium and lanthanum as well as the formation of an adsorption film of oleic acid on steel sliding surfaces.展开更多
The formation of mineral scale is a complex problem during the oilfield operations. Scale inhibitors are widely used to prevent salt precipitation within reservoirs, in downhole equipment, and in production facilities...The formation of mineral scale is a complex problem during the oilfield operations. Scale inhibitors are widely used to prevent salt precipitation within reservoirs, in downhole equipment, and in production facilities. The scale inhibitors not only must have high effectiveness to prevent scale formation, but also have good adsorption- desorption characteristics, which determine the operation duration of the scale inhibitors. This work is focused on the development of a new scale inhibitor for preventing cal- cium carbonate formation in three different synthetic for- mation waters. Scale inhibition efficiency, optical density of the solution, induction time of calcium carbonate for- mation, corrosion activity, and adsorption-desorption ability were investigated for the developed scale inhibitor. The optimum concentration of hydrochloric acid in the inhibitor was determined by surface tension measurement on the boundary layer between oil and the aqueous scale inhibitor solution. The results show that the optimum mass percentage of 5 % hydrochloric acid solution in the inhi- bitor was in the range of 8 % to 10 %. The new scale inhibitor had high efficiency at a concentration of 30 mg/L. The results indicate that the induction period for calcium carbonate nucleation in the presence of the new inhibitor was about 3.5 times longer than the value in the absence of the inhibitors. During the desorption process at reservoir conditions, the number of pore volumes injected into the carbonate core for the developed inhibitor was significantly greater than the volume of a tested industrial inhibitor, showing better adsorption/desorption capacity.展开更多
Tribological properties of 150SN mineral oil and lubricating oils containing triethanolamine borate(TBE)with and without electromagnetic field impact were evaluated on a modified four-ball tribo-tester.The characteris...Tribological properties of 150SN mineral oil and lubricating oils containing triethanolamine borate(TBE)with and without electromagnetic field impact were evaluated on a modified four-ball tribo-tester.The characteristics of the worn surfaces were studied by scanning electronic microscopy(SEM),energy dispersive spectrometry(EDS)and X-ray photoelectron spectroscopy(XPS).Moreover,the tribological mechanisms are discussed from the viewpoint of physical effect and chemical effect.The results indicated that the friction coefficients and wear scar diameters(WSDs)lubricated by 150SN mineral oil under electromagnetic field were higher than those without electromagnetism impact.The WSDs of steel balls lubricated by TBE-doped oils under electromagnetic field were smaller than those obtained from non-electromagnetic field,but the friction coefficients were higher than those under non-electromagnetic field.A protective coating consists of wear particles could be formed on the frictional surface due to the physical effect of electromagnetic field on wear debris.The electromagnetic field could facilitate the interaction of elemental boron and nitrogen in TBE with metal interfaces,and contributes to forming tribo-chemical reaction film to reduce friction and wear.展开更多
Methyl diethanolamine fatty acid esters, viz. methyl diethanolamine octanoate and methyl diethanolamine oleate,were prepared. Their impacts on the biodegradability and tribological properties of mineral base oil 400 S...Methyl diethanolamine fatty acid esters, viz. methyl diethanolamine octanoate and methyl diethanolamine oleate,were prepared. Their impacts on the biodegradability and tribological properties of mineral base oil 400 SN were evaluated by a tester for fast evaluating the biodegradability of lubricants and by a four-ball tester, respectively. The results showed that methyl diethanolamine octanoate and methyl diethanolamine oleate both could markedly promote the biodegradation of the oil and improved its tribological properties. The improvement of biodegradability was attributed to the enhanced growth and quantity of microbes by methyl diethanolamine fatty acid esters. The worn surfaces were analyzed by a scanning electron microscope(SEM) equipped with an energy dispersive spectrometer(EDS) and an X-ray photoelectron spectroscope(XPS). The results indicated that the enhancement of friction-reducing and anti-wear properties of the mineral oil was attributed to the formation of complicated boundary lubrication films composed of species such as Fe_2O_3, Fe_3O_4 and organic nitrogen-containing compounds with a structure of –C-N-or R-NH_2.展开更多
The diesel soot was collected from diesel engine exhaust pipe. The morphology and structure of the collected diesel soot was characterized by HRTEM, XRD and XPS and its tribological behavior was investigated by a SRV ...The diesel soot was collected from diesel engine exhaust pipe. The morphology and structure of the collected diesel soot was characterized by HRTEM, XRD and XPS and its tribological behavior was investigated by a SRV IV oscillating reciprocating friction and wear tester. Test results showed that the tribological behavior of diesel soot was largely influenced by the test load. Under a low load, the diesel soot could reduce the wear volume of the disc. While under a high load, the diesel soot could reduce the friction coefficient of base oil. Based on the characterization of the worn scars by the SEM technique, the 3D surface profiler and the Raman spectroscopy, it was assumed that the core-shell structure of diesel soot with several graphitic layers played important roles. On one hand, its spherical and special structure could make it roll between friction pairs to reduce wear under a low load. On the other hand, its outer-shell graphite layers could be peeled off to form lubrication film to reduce friction under a high load and shear force.展开更多
Oleic acid-capped lanthanum borate(abbreviated as OA/La BO_3·H_2O) nanosheets were prepared by the hydrothermal method. The microstructures of as-prepared OA/La BO_3·H_2O were characterized by means of SEM, ...Oleic acid-capped lanthanum borate(abbreviated as OA/La BO_3·H_2O) nanosheets were prepared by the hydrothermal method. The microstructures of as-prepared OA/La BO_3·H_2O were characterized by means of SEM, TEM, EDS, FTIR and XRD, respectively. Moreover, the friction and wear properties of OA/La BO_3·H_2O as a lubricant additive in rapeseed oil were evaluated on a four-ball tribotester. The tribochemical characteristics of worn surfaces were investigated by SEM and XPS. The results showed that the hydrophobic OA/La BO_3·H_2O nanosheets exhibited their morphology with a diameter in the range of 100 nm to 300 nm and a thickness of about 25 nm, and displayed excellent dispersing stability in rapeseed oil. In the meantime, the rapeseed oil doped with OA/La BO_3·H_2O nanosheets markedly decreased the friction and wear of steel balls, and the optimal friction-reducing and antiwear ability of rapeseed oil was obtained at an OA/La BO_3·H_2O content of 1.0%. The outstanding tribological performance of OA/La BO_3·H_2O in rapeseed oil was attributed to the formation of a composite boundary lubrication film mainly composed of lubricious tribochemical species of B_2O_3, La_2O_3 and Fe_2O_3, and deposits of OA/La BO_3·H_2O nanosheets as well as the adsorbates of rapeseed oil on rubbed surfaces.展开更多
The influence of synthetic caprylic methyl diethanolamine phosphate ester (abbreviated as MDEACP) on biodegradability and tribological properties of 400SN mineral base oil was studied. The biodegradability of the neat...The influence of synthetic caprylic methyl diethanolamine phosphate ester (abbreviated as MDEACP) on biodegradability and tribological properties of 400SN mineral base oil was studied. The biodegradability of the neat base oil and the oil doped with MDEACP was determined on a biodegradation tester. The tribological properties of the neat base oil and the oil doped with MDEACP were evaluated on a four-ball tester. Moreover, the worn surfaces were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results revealed that MDEACP significantly promoted the biodegradation of the mineral base oil. The improvement in biodegradability was attributed to the enhanced growth and quantity of microbes by MDEACP. Furthermore, MDEACP enhanced the anti-wear properties, the friction-reducing properties, and the extreme pressure properties of the base oil. It was mainly attributed to the formation of the complex boundary lubrication film resulted from the adsorption and tribochemical reactions of MDEACP on the friction surface.展开更多
The oil solubility of synthetic oleic acid tris-(2-hydroxyethyl) isocyanurate phosphate ester(abbreviated as OHTP hereinafter) and its influence on the biodegradability and tribological performance of 400 SN mineral o...The oil solubility of synthetic oleic acid tris-(2-hydroxyethyl) isocyanurate phosphate ester(abbreviated as OHTP hereinafter) and its influence on the biodegradability and tribological performance of 400 SN mineral oil were investigated on a tester and a four-ball tribotester,respectively,for fast evaluating the biodegradability of lubricants.Furthermore,the morphologies and tribochemical species of the worn surfaces lubricated by OHTP-doped oil were studied by scanning electron microscope(SEM) and X-ray photoelectron spectroscope(XPS).The results indicated that OHTP possessed good oil solubility and could improve obviously the biodegradability,the extreme pressure properties,the anti-wear properties and friction-reducing properties of the 400 SN mineral oil.The analytical results of XPS spectra showed that the composite boundary lubrication films were mainly composed of absorbed films and tribochemical species such as FePO-4,Fe_3(PO_4)_2,Fe_2O_3 and Fe_3O_4,which contributed to improving the tribological performances.展开更多
Characteristics of Chang 21 low permeability sandstone reservoir of Shunning oil field are analyzed and evaluated based on the data of well logging and experiment. The result shows that 1) the Chang 21 low permeabilit...Characteristics of Chang 21 low permeability sandstone reservoir of Shunning oil field are analyzed and evaluated based on the data of well logging and experiment. The result shows that 1) the Chang 21 low permeability reservoir belongs to the classification of middle-to-fine sized feldspar sandstone, with its components being low in ma- turity, deposited in distributary rivers in the front of the delta; 2) the reservoir is obviously dominated by a low or a very low permeability with a linear variation tendency different from that of the ultra-low permeability reservoir; 3) the spa- tial variation in lithology and physical properties of the reservoir are controlled by the sedimentary facies zones, and 4) the physical property of the reservoir is significantly influenced by clastic constituents and their structure, and the con- stituent of cement materials and their content. The result also shows that the diagenesis action of the reservoir is quite strong in which dissolution greatly modified the reservoir In addition, the inter-granular dissolved pores are the mainly developed ones and the micro-structure is dominated by the combination of middle-to-large sized pores with fine-to-coarse throats. Finally, the radius of the throats is in good exponential correlation with permeability and the seepage capacity comes from those large sized throats.展开更多
Considering electromagnetic effect when investigating tribological properties of rapeseed oil is benefical not only to the improvement of green lubrication, but also to the development of tribology theories and practi...Considering electromagnetic effect when investigating tribological properties of rapeseed oil is benefical not only to the improvement of green lubrication, but also to the development of tribology theories and practices. In the present paper, the tribological properties of rapeseed oil under different intensity of electromagnetic field and normal loads were evaluated on a modified tribo-tester. The results indicated that the electromagnetic field could improve the anti-wear and friction-reducing property of the rapeseed oil. Furthermore, the influencing mechanisms were discussed from the perspective of electromagnetism according to the analytical results of SEM, EDS and XPS techniques.展开更多
When producing hydrocarbons,an important task relates to the optimization of the stock of the producing well.The main complications for wells in non-working mode are represented by the formation of asphalt-resinparaff...When producing hydrocarbons,an important task relates to the optimization of the stock of the producing well.The main complications for wells in non-working mode are represented by the formation of asphalt-resinparaffin deposits.This issue is one of the most common problems in the production and transportation of oil.A promising method to deal with these deposits is the application of smooth coatings made of epoxy polymers on the inner surface of the production well tubing.In this work,a number of laboratory studies were carried out on the“Cold Finger”installation to assess the effectiveness of this approach.These laboratory studies have shown that the efficiency related to smooth coatings is 27%while the resulting thermal conductivity ranges from 0.259 to 0.279 W/(m°C).These results demonstrate that this technology can reduce the amount of organic deposits and increase the temperature of oil.展开更多
Porosity and water saturations are the most important petrophysical parameters of hydrocarbon reservoirs that accurate assessment of them in hydrocarbon reservoirs is an effective tool, important and efficient for ind...Porosity and water saturations are the most important petrophysical parameters of hydrocarbon reservoirs that accurate assessment of them in hydrocarbon reservoirs is an effective tool, important and efficient for industry experts, in the context of a comprehensive study of reservoirs and production and management process of reservoir. In this study, using data from five wells of Mansuri oil field, and using the sequential simulation Gaussian method and using Petrel software, the trend of Porosity and water saturation changes in the mentioned field for four zones was simulated. Also the average maps for each zone have been created that results of the simulation parameters in this map showed that highest average porosity is 0.1401 and 0.2756 at least saturation of water is related to zone 1. Finally result of the simulation indicates the Zone 1 is of the best reservoir Zones.展开更多
Based on the analysis of light hydrocarbon compositions of natural gas and regional comparison in combination with the chemical components and carbon isotopic compositions of methane,the indication of geochemical char...Based on the analysis of light hydrocarbon compositions of natural gas and regional comparison in combination with the chemical components and carbon isotopic compositions of methane,the indication of geochemical characteristics of light hydrocarbons on the migration features,dissolution and escape of natural gas from the Dongsheng gas field in the Ordos Basin is revealed,and the effect of migration on specific light hydrocarbon indexes is further discussed.The study indicates that,natural gas from the Lower Shihezi Formation(Pix)in the Dongsheng gas field displays higher iso-C5-7contents than n-C5-7contents,and the C6-7light hydrocarbons are composed of paraffins with extremely low aromatic contents(<0.4%),whereas the C7light hydrocarbons are dominated by methylcyclohexane,suggesting the characteristics of coal-derived gas with the influence by secondary alterations such as dissolution.The natural gas from the Dongsheng gas field has experienced free-phase migration from south to north and different degrees of dissolution after charging,and the gas in the Shiguhao area to the north of the Borjianghaizi fault has experienced apparent diffusion loss after accumulation.Long-distance migration in free phase results in the decrease of the relative contents of the methylcyclohexane in C7 light hydrocarbons and the toluene/n-heptane ratio,as well as the increase of the n-heptane/methylcyclohexane ratio and heptane values.The dissolution causes the increase of isoheptane values of the light hydrocarbons,whereas the diffusion loss of natural gas in the Shiguhao area results in the increase of n-C5-7contents compared to the iso-C5-7contents.展开更多
基金supported by the Key Research and Development Special Tasks of Xinjiang,China (No.2022B01051-2)the National Natural Science Foundation of China (Nos.U23B2091,42372328,and 52478253)+1 种基金the Natural Science Foundation of Jiangsu Province,China (No.BK20240209)the Science and Technology Program Special Fund of Jiangsu Province (Frontier Leading Technology Basic Research) Major projects,China (No.BK 20222004)
文摘Using cemented rockfill to replace coal pillars offers an effective solution for reducing solid waste while ensuring the safety of gob-side entries.However,achieving the balance among low cost,high waste recycling rates,and adequate strength remains a significant challenge for cemented rockfill.This study used a composite alkali activator to activate gangue cemented rockfill.The compressive strength,scanning electron microscopy,energy dispersive spectrometer,mercury intrusion porosimetry,X-ray diffraction,and thermogra-vimetric tests were carried out to investigate the effect of the composite alkali activator proportion on the compressive strength,micro-structure,and composition of the cemented rockfill.The calcium silicate hydrate(C–S–H)molecular model of cemented rockfill was con-structed to explore the fracture evolution of the nucleated molecular structure under tension.The results show that compressive strength initially increased and then decreased with the activator proportion,the optimal activator proportion of 1:2 resulted in a 31.25%increase in strength at 3 d.This reasonable activator proportion strengthens the pozzolanic effect of gangue,and consumes more calcium hydroxide to inhibit its agglomeration,ultimately achieving the densification of microstructure.The activator proportion inevitably substitutes calcium ions with sodium ions in the C–S–H molecular model.The 12%substitution of calcium ions increases the adhesion between silicon chain layers,which is beneficial to the interlayer stress transfer.This work proposes a method for preparing low-cost cemented rockfill from al-kali-activated gangue,which can be used for solid waste recycling and reducing cement consumption to achieve low-carbon goals.
基金National Natural Science Foundation of China,Grant/Award Numbers:51708016,12172036R&D Program of Beijing Municipal Education Commission,Grant/Award Number:KM202110016014+1 种基金Government of Perm Krai,Research Project,Grant/Award Numbers:СED-26-08-08-28,С-26/628Graduate Innovation Program of Beijing University of Civil Engineering and Architecture,Grant/Award Number:PG2024035。
文摘Microcrack growth during progressive compressive failure in brittle rocks strongly influences the safety of deep underground engineering.The external shear stressτxy on brittle rocks greatly affects microcrack growth and progressive failure.However,the theoretical mechanism of the growth direction evolution of the newly generated wing crack during progressive failure has rarely been studied.A novel analytical method is proposed to evaluate the shear stress effect on the progressive compressive failure and microcrack growth direction in brittle rocks.This model consists of the wing crack growth model under the principal compressive stresses,the direction correlation of the general stress,the principal stress and the initial microcrack inclination,and the relationship between the wing crack length and strain.The shear stress effect on the relationship between y-direction stress and wing crack growth and the relationship between y-direction stress and y-direction strain are analyzed.The shear stress effect on the wing crack growth direction during the progressive compressive failure is determined.The initial crack angle effect on the y-direction peak stress and the wing crack growth direction during the progressive compressive failure considering shear stress is also discussed.A crucial conclusion is that the direction of wing crack growth has a U-shaped variation with the growth of the wing crack.The rationality of the analytical results is verified by an experiment and from numerical results.The study results provide theoretical support for the evaluation of the safety and stability of surrounding rocks in deep underground engineering.
基金supported by the National Natural Science Foundation of China,China(No.52474088).
文摘Liquid hydrogen has attracted much attention due to its high energy storage density and suitability for long-distance transportation.An efficient hydrogen liquefaction process is the key to obtaining liquid hydrogen.In an effort to determine the parameter optimization of the hydrogen liquefaction process,this paper employed process simulation software Aspen HYSYS to simulate the hydrogen liquefaction process.By establishing a dynamic model of the unit module,this study carried out dynamic simulation optimization based on the steady-state process and process parameters of the hydrogen liquefaction process and analyzed the dynamic characteristics of the process.Based on the pressure drop characteristic experiment,an equation for the pressure drop in the heat exchanger was proposed.The heat transfer of hydrogen conversion was simulated and analyzed,and its accuracy was verified by comparison with the literature.The dynamic simulation of a plate-fin heat exchanger was carried out by coupling heat transfer simulation and the pressure drop experiment.The results show that the increase in inlet temperature(5℃and 10℃)leads to an increase in specific energy consumption(0.65%and 1.29%,respectively)and a decrease in hydrogen liquefaction rate(0.63%and 2.88%,respectively).When the inlet pressure decreases by 28.57%,the hydrogen temperature of the whole liquefaction process decreases and the specific energy consumption increases by 52.94%.The research results are of great significance for improving the operating efficiency of the refrigeration cycle and guiding the actual liquid hydrogen production.
基金Ministry of Science and Higher Education of the Russian Federation,Grant/Award Number:FSNM-2024-0005Korea Institute of Energy Technology Evaluation and Planning,Grant/Award Number:20225B10300080Yayasan UTP,Grant/Award Number:015LC0-526。
文摘Carbon capture and storage(CCS)remains one of the most feasible techniques for the control of Greenhouse gas emission levels.However,there will always be risks attached to the subsurface injection of CO_(2).These could be in the form of leakages from the injection wellbore due to completion failure;escape of the injected CO_(2)to neighboring aquifers due to the heterogeneous or fractured nature of the storage site;or seepage at the surface due to inadequacy of the sealing cap rock.While all these may occur,the most cost-effective and timely way to reduce the risk of leakages is by plugging the pathways.This is done using either traditional Cementous materials or more augmented sealants like organic gels and resins.A lot of studies in the literature have described this collection of materials within the context of CO_(2)conformance control.So also,there are reviews on the classification and description of these chemicals.This review provides a more systemic evaluation of these classes of chemicals.This is by providing critical analyses of how external factors like CO_(2),pH,brine salinity and hardness,rock mineralogy,pressure,temperature,and injectivity could affect the performance of different sealants that can be utilized.Based on these assessments,best practices for the application of the sealants,both at the testing stage in the laboratory and the pilot stage and field deployment,are suggested.
基金funded by the Ministry of Science and Higher Education of the Russian Federation(Project No.FSNM-2023-0005).
文摘Many new and developed oilfields are confined to carbonate reservoirs with a complex void space structure.In this study,the behavior of carbonates as a function of decreased reservoir pressure was examined.The study was based on actual production data from wells rather than just on model data or results from computational experiments.Well-test data(170 well tests)and laboratory core samples(45 samples)results were used in the analysis.The problem of reservoir deformation has been compre-hensively addressed at the micro and macro levels.The effect of reservoir permeability throughout the entire reservoir volume on reservoir pressure was determined.With a decline in reservoir pressure,the permeability of fractures and pores in carbonates decreases.The deformation coefficients,which char-acterize the actual rate of decrease in permeability with decreasing reservoir pressure,were also calculated.The deformation coefficients and data from core studies using μ-CT and SEM were compared.Based on micro-CT data,the effective diameters of the voids were calculated to be 93μm,109μm,and 140μm for the Vinnikovskoe,Sofinskoe,and Sukharev fields,respectively.Based on μ-CT and SEM data,the predominant geometric shapes of the voids were assessed.The deformation coefficient of voids was found to depend on their size and geometric shape.The study's findings revealed deformation co-efficients of 0.172,0.205,and 0.748 for the Vinnikovskoe,Sofinskoe,and Sukharev fields,respectively.Maximum deformation coefficients are typical for large voids with a predominant slot-like shape.However,even with the predominance of primary spherical voids in carbonates,the permeability of voids decreases with decreasing reservoir pressure.
文摘Nowadays,the development of effective bioplastics aims to combine traditional plastics’functionality with environmentally friendly properties.The most effective and durable modern bioplastics are made from the edible part of crops.This forces bioplastics to competewith food production because the crops that produce bioplastics can also be used for human nutrition.That is why the article’s main focus is on creating bioplastics using renewable,non-food raw materials(cellulose,lignin,etc.).Eco-friendly composites based on a renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch,and poly(lactic acid)with reed and hemp waste as a filler.The physic-chemical features of the structure and surface,as well as the technological characteristics of reed and hemp waste as the organic fillers for renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch,and poly(lactic acid),were studied.Theeffect of the fractional composition analysis,morphology,and nature of reed and hempwaste on the quality of the design of eco-friendly biodegradable composites and their ability to disperse in the matrix of renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch and poly(lactic acid)was carried out.The influence of different content and morphology of reed and hemp waste on the composite characteristics was investigated.It is shown that the most optimal direction for obtaining strong eco-friendly biodegradable composites based on a renewable bioplastic blend of polybutylene adipate-co-terephthalate,corn starch,and poly(lactic acid)is associated with the use of waste reed stalks,with its optimal content at the level of 50 wt.%.
基金Projects(52174092,42472338,51904290)supported by the National Natural Science Foundation of ChinaProject(BK20220157)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(2022YCPY0202)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This study investigates the shear mechanical responses and debonding failure mechanisms of anchoring systems comprising three anisotropic media and two anisotropic interfaces under controlled boundary conditions of constant normal load(F_(s)),constant normal stiffness(K),and shear rate(v).A systematic analysis of shear mechanical properties,the evolution of maximum principal strain field,and damage characteristics along shear failure surface is presented.Results from direct shear tests demonstrate that initial shear slip diminishes with increasing F_(s)and K,attributed to the normal constraint strengthening effect,while an increase in v enhances initial shear slip due to attenuated deformation coordination and stress transfer.As F_(s)increases from 7.5 to 120 kN,K from 0 to 12 MPa/mm,and v from 0.1 to 2 mm/min,the peak shear load increases by 210.32%and 80.16%with rising F_(s)and K,respectively,while decreases by 38.57%with increasing v.Correspondingly,the shear modulus exhibits,respectively,a 135.29%and 177.06%increase with rising F_(s)and K,and a 37.03%decrease with larger v.Initial shear dilation is identified as marking the formation of shear failure surface along anisotropic interfaces,resulting from the combined shear actions at the resin bolt interface,where resin undergoes shear by bolt surface protrusions,and the resin-rock interface,where mutual shear occurs between resin and rock.With increasing F_(s)and K and decreasing v,the location of the shear failure surface shifts from the resin-rock interface to the resin-bolt interface,accompanied by a transition in failure mode from tensile rupture of resin to shear off at the resin surface.
基金supported by National Natural Science Foundation of China(50975282)
文摘Oleic acid （denoted as OA） surface-capped lanthanum-doped titanium dioxide composite nanoparticles, abbreviated as OA/La-TiO2, were prepared via sol-gel method in association with surface modification by oleic acid. The microstructure of as-prepared OA/La-TiO2 was characterized by means of X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrometry, and their thermal stability was evaluated by thermogravimetry and differential scanning calorimetry. Moreover, the tribological properties of OA/La-TiO2 as lubricant additives in rapeseed oil were evaluated with a four-ball friction and wear tester. The morphology as well as elemental composition and chemical characteristics of worn steel surfaces was investigated by scanning electron microscopy, energy dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. Results showed that as-prepared OA/La-TiO2 particles were of spherical shape and had an average diameter of 20 nm. In the meantime, OA/La-TiO2 particles doped with 1.5% （molar ratio; the same hereafter） and 2.5% of lanthanum could markedly improve the anti-wear and friction-reducing capacities of rapeseed oil. This is attributed to the formation of a complex boundary lubrication film mainly composed of the oxides of iron, titanium and lanthanum as well as the formation of an adsorption film of oleic acid on steel sliding surfaces.
文摘The formation of mineral scale is a complex problem during the oilfield operations. Scale inhibitors are widely used to prevent salt precipitation within reservoirs, in downhole equipment, and in production facilities. The scale inhibitors not only must have high effectiveness to prevent scale formation, but also have good adsorption- desorption characteristics, which determine the operation duration of the scale inhibitors. This work is focused on the development of a new scale inhibitor for preventing cal- cium carbonate formation in three different synthetic for- mation waters. Scale inhibition efficiency, optical density of the solution, induction time of calcium carbonate for- mation, corrosion activity, and adsorption-desorption ability were investigated for the developed scale inhibitor. The optimum concentration of hydrochloric acid in the inhibitor was determined by surface tension measurement on the boundary layer between oil and the aqueous scale inhibitor solution. The results show that the optimum mass percentage of 5 % hydrochloric acid solution in the inhi- bitor was in the range of 8 % to 10 %. The new scale inhibitor had high efficiency at a concentration of 30 mg/L. The results indicate that the induction period for calcium carbonate nucleation in the presence of the new inhibitor was about 3.5 times longer than the value in the absence of the inhibitors. During the desorption process at reservoir conditions, the number of pore volumes injected into the carbonate core for the developed inhibitor was significantly greater than the volume of a tested industrial inhibitor, showing better adsorption/desorption capacity.
基金financial support provided by the Basic Science and Frontier Technology Research Project of Chongqing (CSTC, 2017jcyjAX0058)
文摘Tribological properties of 150SN mineral oil and lubricating oils containing triethanolamine borate(TBE)with and without electromagnetic field impact were evaluated on a modified four-ball tribo-tester.The characteristics of the worn surfaces were studied by scanning electronic microscopy(SEM),energy dispersive spectrometry(EDS)and X-ray photoelectron spectroscopy(XPS).Moreover,the tribological mechanisms are discussed from the viewpoint of physical effect and chemical effect.The results indicated that the friction coefficients and wear scar diameters(WSDs)lubricated by 150SN mineral oil under electromagnetic field were higher than those without electromagnetism impact.The WSDs of steel balls lubricated by TBE-doped oils under electromagnetic field were smaller than those obtained from non-electromagnetic field,but the friction coefficients were higher than those under non-electromagnetic field.A protective coating consists of wear particles could be formed on the frictional surface due to the physical effect of electromagnetic field on wear debris.The electromagnetic field could facilitate the interaction of elemental boron and nitrogen in TBE with metal interfaces,and contributes to forming tribo-chemical reaction film to reduce friction and wear.
基金financial supports from National Defense Science Technology Foundation (Project No.3604003)National Natural Science Foundation of China (Project No.51375491)+1 种基金Natural Science Foundation of Chongqing (Project No. CSTC 2014JCYJAA50021)Natural Science Foundation of Chongqing (Project No. cstc2017jcyjAX0058)
文摘Methyl diethanolamine fatty acid esters, viz. methyl diethanolamine octanoate and methyl diethanolamine oleate,were prepared. Their impacts on the biodegradability and tribological properties of mineral base oil 400 SN were evaluated by a tester for fast evaluating the biodegradability of lubricants and by a four-ball tester, respectively. The results showed that methyl diethanolamine octanoate and methyl diethanolamine oleate both could markedly promote the biodegradation of the oil and improved its tribological properties. The improvement of biodegradability was attributed to the enhanced growth and quantity of microbes by methyl diethanolamine fatty acid esters. The worn surfaces were analyzed by a scanning electron microscope(SEM) equipped with an energy dispersive spectrometer(EDS) and an X-ray photoelectron spectroscope(XPS). The results indicated that the enhancement of friction-reducing and anti-wear properties of the mineral oil was attributed to the formation of complicated boundary lubrication films composed of species such as Fe_2O_3, Fe_3O_4 and organic nitrogen-containing compounds with a structure of –C-N-or R-NH_2.
基金the financial support of the Logistics Key Basic Research Program of PLA (BX214C006)the Chongqing Science and Technology Achievement Transformation Fund (KJZH17139)
文摘The diesel soot was collected from diesel engine exhaust pipe. The morphology and structure of the collected diesel soot was characterized by HRTEM, XRD and XPS and its tribological behavior was investigated by a SRV IV oscillating reciprocating friction and wear tester. Test results showed that the tribological behavior of diesel soot was largely influenced by the test load. Under a low load, the diesel soot could reduce the wear volume of the disc. While under a high load, the diesel soot could reduce the friction coefficient of base oil. Based on the characterization of the worn scars by the SEM technique, the 3D surface profiler and the Raman spectroscopy, it was assumed that the core-shell structure of diesel soot with several graphitic layers played important roles. On one hand, its spherical and special structure could make it roll between friction pairs to reduce wear under a low load. On the other hand, its outer-shell graphite layers could be peeled off to form lubrication film to reduce friction under a high load and shear force.
基金the financial support of the National Natural Science Foundation of China(Project 50975282)
文摘Oleic acid-capped lanthanum borate(abbreviated as OA/La BO_3·H_2O) nanosheets were prepared by the hydrothermal method. The microstructures of as-prepared OA/La BO_3·H_2O were characterized by means of SEM, TEM, EDS, FTIR and XRD, respectively. Moreover, the friction and wear properties of OA/La BO_3·H_2O as a lubricant additive in rapeseed oil were evaluated on a four-ball tribotester. The tribochemical characteristics of worn surfaces were investigated by SEM and XPS. The results showed that the hydrophobic OA/La BO_3·H_2O nanosheets exhibited their morphology with a diameter in the range of 100 nm to 300 nm and a thickness of about 25 nm, and displayed excellent dispersing stability in rapeseed oil. In the meantime, the rapeseed oil doped with OA/La BO_3·H_2O nanosheets markedly decreased the friction and wear of steel balls, and the optimal friction-reducing and antiwear ability of rapeseed oil was obtained at an OA/La BO_3·H_2O content of 1.0%. The outstanding tribological performance of OA/La BO_3·H_2O in rapeseed oil was attributed to the formation of a composite boundary lubrication film mainly composed of lubricious tribochemical species of B_2O_3, La_2O_3 and Fe_2O_3, and deposits of OA/La BO_3·H_2O nanosheets as well as the adsorbates of rapeseed oil on rubbed surfaces.
基金financial support from the National Defense Science Technology Foundation (Project No.3604003)the National Natural Science Foundation of China (Project No.51375491)+2 种基金the Natural Science Foundation of Chongqing (Project No. CSTC, 2014JCYJAA50021)the Postgraduate Research and the Innovation Project of Chongqing (No. CYB 18128)the Natural Science Foundation of Chongqing (Project No. CSTC, 2017JCYJAX0058)
文摘The influence of synthetic caprylic methyl diethanolamine phosphate ester (abbreviated as MDEACP) on biodegradability and tribological properties of 400SN mineral base oil was studied. The biodegradability of the neat base oil and the oil doped with MDEACP was determined on a biodegradation tester. The tribological properties of the neat base oil and the oil doped with MDEACP were evaluated on a four-ball tester. Moreover, the worn surfaces were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results revealed that MDEACP significantly promoted the biodegradation of the mineral base oil. The improvement in biodegradability was attributed to the enhanced growth and quantity of microbes by MDEACP. Furthermore, MDEACP enhanced the anti-wear properties, the friction-reducing properties, and the extreme pressure properties of the base oil. It was mainly attributed to the formation of the complex boundary lubrication film resulted from the adsorption and tribochemical reactions of MDEACP on the friction surface.
基金the financial support from the National Defense Science Technology Foundation (Project No.3604003)the National Natural Science Foundation of China (Project No.51375491)+1 种基金the Natural Science Foundation of Chongqing (Project No.CSTC,2014JCYJAA50021)the Natural Science Foundation of Chongqing (Project No.cstc2017jcyj AX0058)
文摘The oil solubility of synthetic oleic acid tris-(2-hydroxyethyl) isocyanurate phosphate ester(abbreviated as OHTP hereinafter) and its influence on the biodegradability and tribological performance of 400 SN mineral oil were investigated on a tester and a four-ball tribotester,respectively,for fast evaluating the biodegradability of lubricants.Furthermore,the morphologies and tribochemical species of the worn surfaces lubricated by OHTP-doped oil were studied by scanning electron microscope(SEM) and X-ray photoelectron spectroscope(XPS).The results indicated that OHTP possessed good oil solubility and could improve obviously the biodegradability,the extreme pressure properties,the anti-wear properties and friction-reducing properties of the 400 SN mineral oil.The analytical results of XPS spectra showed that the composite boundary lubrication films were mainly composed of absorbed films and tribochemical species such as FePO-4,Fe_3(PO_4)_2,Fe_2O_3 and Fe_3O_4,which contributed to improving the tribological performances.
文摘Characteristics of Chang 21 low permeability sandstone reservoir of Shunning oil field are analyzed and evaluated based on the data of well logging and experiment. The result shows that 1) the Chang 21 low permeability reservoir belongs to the classification of middle-to-fine sized feldspar sandstone, with its components being low in ma- turity, deposited in distributary rivers in the front of the delta; 2) the reservoir is obviously dominated by a low or a very low permeability with a linear variation tendency different from that of the ultra-low permeability reservoir; 3) the spa- tial variation in lithology and physical properties of the reservoir are controlled by the sedimentary facies zones, and 4) the physical property of the reservoir is significantly influenced by clastic constituents and their structure, and the con- stituent of cement materials and their content. The result also shows that the diagenesis action of the reservoir is quite strong in which dissolution greatly modified the reservoir In addition, the inter-granular dissolved pores are the mainly developed ones and the micro-structure is dominated by the combination of middle-to-large sized pores with fine-to-coarse throats. Finally, the radius of the throats is in good exponential correlation with permeability and the seepage capacity comes from those large sized throats.
基金financially supported by the National Natural Science Foundation of China (Project No. 51375491)the Natural Science Foundation of Chongqing(Project No. CSTC, 2014JCYJAA50021)the Youth Fund of Logistical Engineering University (No. YQ16-420801)
文摘Considering electromagnetic effect when investigating tribological properties of rapeseed oil is benefical not only to the improvement of green lubrication, but also to the development of tribology theories and practices. In the present paper, the tribological properties of rapeseed oil under different intensity of electromagnetic field and normal loads were evaluated on a modified tribo-tester. The results indicated that the electromagnetic field could improve the anti-wear and friction-reducing property of the rapeseed oil. Furthermore, the influencing mechanisms were discussed from the perspective of electromagnetism according to the analytical results of SEM, EDS and XPS techniques.
基金The research was carried out at the expense of the Russian Science Foundation Grant No.21-79-10403,https://rscf.ru/project/21-79-10403/.
文摘When producing hydrocarbons,an important task relates to the optimization of the stock of the producing well.The main complications for wells in non-working mode are represented by the formation of asphalt-resinparaffin deposits.This issue is one of the most common problems in the production and transportation of oil.A promising method to deal with these deposits is the application of smooth coatings made of epoxy polymers on the inner surface of the production well tubing.In this work,a number of laboratory studies were carried out on the“Cold Finger”installation to assess the effectiveness of this approach.These laboratory studies have shown that the efficiency related to smooth coatings is 27%while the resulting thermal conductivity ranges from 0.259 to 0.279 W/(m°C).These results demonstrate that this technology can reduce the amount of organic deposits and increase the temperature of oil.
文摘Porosity and water saturations are the most important petrophysical parameters of hydrocarbon reservoirs that accurate assessment of them in hydrocarbon reservoirs is an effective tool, important and efficient for industry experts, in the context of a comprehensive study of reservoirs and production and management process of reservoir. In this study, using data from five wells of Mansuri oil field, and using the sequential simulation Gaussian method and using Petrel software, the trend of Porosity and water saturation changes in the mentioned field for four zones was simulated. Also the average maps for each zone have been created that results of the simulation parameters in this map showed that highest average porosity is 0.1401 and 0.2756 at least saturation of water is related to zone 1. Finally result of the simulation indicates the Zone 1 is of the best reservoir Zones.
基金Supported by the National Natural Science Foundation of China(42172149,U2244209)Sinopec Science and Technology Research Project(P23230,P22132)。
文摘Based on the analysis of light hydrocarbon compositions of natural gas and regional comparison in combination with the chemical components and carbon isotopic compositions of methane,the indication of geochemical characteristics of light hydrocarbons on the migration features,dissolution and escape of natural gas from the Dongsheng gas field in the Ordos Basin is revealed,and the effect of migration on specific light hydrocarbon indexes is further discussed.The study indicates that,natural gas from the Lower Shihezi Formation(Pix)in the Dongsheng gas field displays higher iso-C5-7contents than n-C5-7contents,and the C6-7light hydrocarbons are composed of paraffins with extremely low aromatic contents(<0.4%),whereas the C7light hydrocarbons are dominated by methylcyclohexane,suggesting the characteristics of coal-derived gas with the influence by secondary alterations such as dissolution.The natural gas from the Dongsheng gas field has experienced free-phase migration from south to north and different degrees of dissolution after charging,and the gas in the Shiguhao area to the north of the Borjianghaizi fault has experienced apparent diffusion loss after accumulation.Long-distance migration in free phase results in the decrease of the relative contents of the methylcyclohexane in C7 light hydrocarbons and the toluene/n-heptane ratio,as well as the increase of the n-heptane/methylcyclohexane ratio and heptane values.The dissolution causes the increase of isoheptane values of the light hydrocarbons,whereas the diffusion loss of natural gas in the Shiguhao area results in the increase of n-C5-7contents compared to the iso-C5-7contents.
