The formation of copper deposits is closely related to hydrothermal processes.Understanding the migration of copper in hydrothermal fluids aids in reconstructing mineralization processes and deciphering deposit genesi...The formation of copper deposits is closely related to hydrothermal processes.Understanding the migration of copper in hydrothermal fluids aids in reconstructing mineralization processes and deciphering deposit genesis.Copper primarily exists as Cu^(+)and Cu^(2+)in hydrothermal solutions,with redox conditions governing their interconversion.In chloride-rich geological fluids,Cu-Cl complexes are considered critical for copper transport.However,the specific types and valence transitions of Cu-Cl complexes under varying hydrothermal conditions remain poorly understood.This study employed in situ Raman spectroscopy to systematically analyze Cu+HCl and CuCl_(2)+K_(2)S_(2)O_(3)/H_(2) systems under saturated vapor pressure at 25-300℃,elucidating the effects of temperature,Cl^(-)concentration,and redox conditions on copper speciation.In the Cu^(+)HCl system,copper dissolved as monovalent Cu-Cl complexes.At high temperatures(>200℃),[CuCl_(2)]^(-)is the dominated species,whereas[CuCl_(3)]^(2-)becomes prevalent at lower temperatures and higher HCl concentrations.For the Cu^(2+)-Cl system,the dominant species transitioned from[Cu(H_(2)O)n]^(2+)(<50℃)to[CuCl_(4)]^(2-)(100℃)and further to[CuCl]^(+)and[CuCl_(2)]^(0) at 300℃.The introduction of reducing agents(K_(2)S_(2)O_(3)/H_(2))facilitated Cu^(2+)→Cu^(+)reduction,thereby stabilizing Cu^(+)-Cl complexes and inducing partial copper precipitation.The behavior of copper in chloriderich hydrothermal fluids observed in this study indicates that high-temperature oxidizing fluids facilitate Cu mobilization,while cooling and redox changes promote deposition and ore minerals formation.展开更多
Supercritical fluids play a crucial role in material transport within Earth's deep interior.Investigating the pressure-dependent atomic structures and transport properties of such fluids is essential for understan...Supercritical fluids play a crucial role in material transport within Earth's deep interior.Investigating the pressure-dependent atomic structures and transport properties of such fluids is essential for understanding their petrological,chemical,and geophysical behaviors.In this study,we employed first-principles molecular dynamics simulations to explore the structures,self-diffusion coefficients(D),and viscosities(η)of supercritical NaAlSi_(3)O_(8)-H_(2)O fluids under conditions of 2000 K and 3-10 GPa,with water contents of 30 wt% and 50 wt%.Our calculations indicate that at a water content of 30 wt%,Q^(2) and Q^(3) exhibit a certain degree of positive and negative pressure dependence,respectively,while other Q^(n) species(n represents the number of bridging oxygens connected to Si/Al)show minimal changes.At a water content of 50 wt%,Q^(2) and Q^(0) exhibit a certain degree of positive and negative pressure dependence,respectively,while other Q^(n) species show minimal changes.At both water contents,Si-O-H and molecular water in the system exhibit negative pressure dependence,suggesting that the migration of supercritical fluids from deep to shallow regions is accompanied by the release of water.The self-diffusion coefficients in the supercritical NaAlSi_(3)O_(8)-H_(2)O fluid follow the order D_(Na)≈D_(H)>D_(O)>D_(Al)≈D_(Si),with an overall weak negative pressure dependence.By comparing the viscosities of anhydrous and hydrous silicate melts from previous studies,we found that the addition of water caused a transition from negative to positive pressure dependence of viscosity,corresponding to a structural change from polymerization to depolymerization.Additionally,we calculated the fluid mobility Δp/η of supercritical NaAlSi_(3)O_(8)-H_(2)O fluids and found that their mobility is several orders of magnitude higher than that of basalt melt and is also significantly greater than that of carbonate melt.As supercritical fluids ascend from deeper to shallower regions,their mobility is further enhanced,significantly contributing to the transport of elements from subducting slabs to the overlying mantle wedge.展开更多
Transcritical and supercritical fluids widely exist in aerospace propulsion systems,such as the coolant flow in the regenerative cooling channels of scramjet engines.To numerically simulate the coolant flow,we must ad...Transcritical and supercritical fluids widely exist in aerospace propulsion systems,such as the coolant flow in the regenerative cooling channels of scramjet engines.To numerically simulate the coolant flow,we must address the challenges in solving Riemann problems(RPs)for real fluids under complex flow conditions.In this study,an exact numerical solution for the one-dimensional RP of two-parameter fluids is developed.Due to the comprehensive resolution of fluid thermodynamics,the proposed solution framework is suitable for all forms of the two-parameter equation of state(EoS).The pressure splitting method is introduced to enable parallel calculation of RPs across multiple grid points.Theoretical analysis demonstrates the isentropic nature of weak waves in two-parameter fluids,ensuring that the same mathematical properties as ideal gas could be applied in Newton's iteration.A series of numerical cases validate the effectiveness of the proposed method.A comparative analysis is conducted on the exact Riemann solutions for the real fluid EoS,the ideal gas EoS,and the improved ideal gas EoS under supercritical and transcritical conditions.The results indicate that the improved one produces smaller errors in the calculation of momentum and energy fluxes.展开更多
The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified i...The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified in the region via exploration.However,metallogenic sources and evolution of W remain unclear,and the existing metallogenic model has to be updated to guide further ore prospecting.Elemental and Sr-Nd isotopic data for scheelites assist in the determination of sources and evolution of the W-mineralizing fluids and metals in the district.Based on field geological survey,the scheelites in the Gejiu district can be categorized into three types:altered granite(Type Ⅰ),quartz vein(Type Ⅱ)from the Laochang deposit,and skarn(Type Ⅲ)from the Kafang deposit.Types Ⅰ and Ⅱ scheelites have low molybdenum(Mo)and strontium(Sr)contents,and Type Ⅱ scheelite has lower Sr contents than Type Ⅰ as well as higher Mo and Sr contents than Type Ⅲ scheelites.Varying Mo contents across the scheelite types suggests that the oxygen fugacity varied during ore accumulation.Type Ⅰ and Type Ⅱ scheelites exhibit similar rare earth elements(REE)patterns;Type Ⅲ scheelite contains lower REE content,particularly HREE,compared with the other scheelites.All scheelites exhibit negative Eu anomalies in the chondrite-normalized REE patterns.As the W-mineralization and two-mica granite share close spatial and temporal relationships,the negative Eu anomalies were likely inherited from the two-mica granite.Type Ⅰ and Type Ⅱ scheelites display varied(^(87)Sr/^(86)Sr)_(82 Ma)(0.7090-0.7141)andε_(Nd)(82 Ma)(from−9.9 to−5.4)values,similar to those of granite.However,Type Ⅲ scheelite exhibits lower(^(87)Sr/^(86)Sr)_(82 Ma)(0.7083-0.7087)and lowerε_(Nd)(82 Ma)(from−10.5 to−6.9)values than the two-mica granite.This indicates that the two-mica granite alone did not provide the ore-forming fluids and metals and that the Type Ⅲ scheelite ore-forming fluids likely involved external fluids that were probably derived from carbonate rocks.The implication is that highly differentiated two-mica granites were the source of primary W-bearing metals and fluids,which is consistent with earlier research on the origin of Sn ore-forming materials.展开更多
This study presents a theoretical and experimental analysis of laminar flow behavior of high-viscous non-Newtonian power-law and Bingham fluids in multiple structural bifurcation channel distributors.Theoretical model...This study presents a theoretical and experimental analysis of laminar flow behavior of high-viscous non-Newtonian power-law and Bingham fluids in multiple structural bifurcation channel distributors.Theoretical models are derived to describe velocity profiles,shear rate distribution,and pressure drop across specific channels.Modified pressure drop models are proposed based on experiments on 6 kinds of non-Newtonian fluids and 3 types of bifurcation channel distributors with different transition areas.Specifically,the deviations between the theoretical models and the experimental results are systematically analyzed,and models were modified with correction coefficients based on Reynolds number and dimensionless shape factor.The theoretical results,modified results and experimental data are compared and discussed to ensure the accuracy of the modified models,demonstrating a significant improvement in the prediction of pressure drops for high-viscous non-Newtonian fluids in certain types of bifurcation channels.Additional experiments and analyses were carried out to validate the modified models and the results suggest that the models offer a certain degree of universal applicability in bifurcation channel designs.It implies that for other types of bifurcation channel distributors,similar correction methods based on Reynolds number and shape factor may also be applicable even with different coefficients.展开更多
Understanding the thermodynamic behavior of complex fluids in confined environments is critical for various industrial and natural processes including but not limited to polymer flooding enhanced oil recovery(EOR).In ...Understanding the thermodynamic behavior of complex fluids in confined environments is critical for various industrial and natural processes including but not limited to polymer flooding enhanced oil recovery(EOR).In this work,we develop Atif-V2.0,an extended classical density functional theory(cDFT)framework that integrates the interfacial statistical associating fluid theory(iSAFT)to model multicomponent associating fluids composed of water-soluble polymers,alkanes,and water.Building on the original theoretical framework of Atif for modeling nanoconfined inhomogeneous fluids,Atif-V2.0 embeds explicit solvent and captures additional physical interactions-hydrogen bonding,which are critical in associating fluid systems.The other key feature of Atif-V2.0 is its ability to account for polymer topology.We demonstrate its capability by predicting the equilibrium structure and thermodynamic behavior of branched hydrolyzed polyacrylamide solutions near hard walls with various branching topologies,which provides a robust theoretical tool for the rational design of EOR polymers.展开更多
Aiming at the leakage problem in the compact sandstone drilling of the Keziluoyi Formation in South-west Tarim,Nano-core-emulsion was prepared by coating modified nano-SiO_(2) with nano-emulsion,its particle size D50 ...Aiming at the leakage problem in the compact sandstone drilling of the Keziluoyi Formation in South-west Tarim,Nano-core-emulsion was prepared by coating modified nano-SiO_(2) with nano-emulsion,its particle size D50 is about 100 nm,with good dispersion stability.When 0.8%Nano-core-emulsion is added to 5%bentonite slurry,the fluid loss can be reduced by 40%,and the filter cake thickness can be reduced by 84%.Using a Nano-core-emulsion to optimize the plugging performance of potassium pol-ysulfonate drilling fluid can reduce the fluid loss of the drilling fluid by 52%,the resulting filter cake is dense and tough,and the thickness is reduced by 40%.Using the pressure conduction method to evaluate the plugging rate,the plugging rate of the drilling fluid of the Nano-core-emulsion on the core of the Keziluoyi Formation is 63.4%,which is 20.9%higher than that of the field drilling fluid.According to microscopic examination and CT scanning analysis,the material has the plugging characteristics of"inner rigid support+outer soft deformation"and has demonstrated good field application results.展开更多
Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducte...Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs.In this study,the micromixing efficiency in MCRs was experimentally investigated using CMC(carboxymethyl cellulose sodium)aqueous solution to simulate a non-Newtonian fluid,and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics(CFD)simulations.The results show that in the conventional channel,increasing the flow rate improves the micromixing efficiency when the CMC concentration is low.However,when the CMC concentration is higher,the higher the flow rate,the lower the micromixing efficiency.The highest micromixing efficiency is obtained for the rotationally coupled inner components,followed by the single rotation and the lowest is for the internals only.CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor,which effectively reduces the apparent viscosity.These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.展开更多
Drilling operations in carbonate rock heavy oil blocks(e.g.,in the Tahe Oilfield)are challenged by the intrusion of high-viscosity,temperature-sensitive formation heavy oil into the drilling fluid.This phenomenon ofte...Drilling operations in carbonate rock heavy oil blocks(e.g.,in the Tahe Oilfield)are challenged by the intrusion of high-viscosity,temperature-sensitive formation heavy oil into the drilling fluid.This phenomenon often results in wellbore blockage,reduced penetration rates,and compromised well control,thereby significantly limiting drilling efficiency and operational safety.To address this issue,this study conducts a comprehensive investigation into the mechanisms governing heavy oil invasion using a combination of laboratory experiments and field data analysis.Findings indicate that the reservoir exhibits strong heterogeneity and that the heavy oil possesses distinctive physical properties.The intrusion process is governed by multiple interrelated factors,including pressure differentials,pore structure,and the rheological behavior of the heavy oil.Experimental results reveal that the invasion of heavy oil occurs in distinct phases,with temperature playing a critical role in altering its viscosity.Specifically,as temperature increases,the apparent viscosity of the drilling fluid decreases;however,elevated pressures induce a nonlinear increase in viscosity.Furthermore,the compatibility between the drilling fluid and the intruding heavy oil declines markedly with increasing oil concentration,substantially raising the risk of wellbore obstruction.Simulation experiments further confirm that at temperatures exceeding 40℃and injection rates of L/min,the likelihood of wellbore blockage significantly≥0.4increases due to heavy oil infiltration.Based on these insights,a suite of targeted mitigation strategies is proposed.These include the formulation of specialized chemical additives,such as viscosity reducers,dispersants,and plugging removal agents,the real-time adjustment of drilling fluid density,and the implementation of advanced monitoring and early-warning systems.展开更多
Self-propulsion of a deformable ellipse immersed in an unbounded inviscid fluid is discussed in order to explore the effect of the deformation and controlled rotation of the body coupled with the shift of its internal...Self-propulsion of a deformable ellipse immersed in an unbounded inviscid fluid is discussed in order to explore the effect of the deformation and controlled rotation of the body coupled with the shift of its internal mass on the self-motion.The ellipse is capable of symmetric deformation along the two orthogonal axes and endowed with some self-regulation ability via the shift and rotation of its internal mass.From the model,the appropriate velocity potential induced by the motion of the ellipse with the deformation in an otherwise undisturbed fluid is derived,and then the equations of motion are obtained by means of integrals of the unsteady fluid pressure.The equations are utilized to explore self-translational behaviors of the ellipse through the cyclic shift of its internal mass and deformation coupled with its own controllable rotation.Analysis and numerical results show that the ellipse can break the kinematic time-reversal symmetry by properly adjusting its own rotation to coordinate with the deformation and the cyclic shift of the inner mass to meet a forward criterion,and push itself to move persistently forward without a regression at zero system momentum,exhibiting some basic serpentine movements according as the ellipse performs complete revolutions or oscillates between two extreme yaw angles during its self-motion.展开更多
Jadeitites are formed either through direct precipitation from Na-Al-Si rich fluids(P-type),or by replacement of magmatic protoliths(R-type)in subduction zones.They are valuable targets for investigating the mobility ...Jadeitites are formed either through direct precipitation from Na-Al-Si rich fluids(P-type),or by replacement of magmatic protoliths(R-type)in subduction zones.They are valuable targets for investigating the mobility behavior and chemical composition of subduction zone fluids.The Rio San Juan Complex(RSJC)in the northern Dominican Republic hosts both P-and R-type jadeitites and jadeite-rich rocks,which provide ideal samples for addressing such issues.Here,we present trace element and Sr-Nd-O-Si isotope compositions of RSJC jadeitites and related rocks.Most samples show similar REE patterns,trace element distributions and δ^(18)O values to those of plagiogranite protoliths,indicating the predominance of R-type origin in RSJC.The P-type samples exhibit slightly higherδ^(30)Si values(−0.15‰to 0.25‰)than that of R-type samples(−0.20‰to 0.08‰),which place above the igneous array.The low(^(87)Sr/^(86)Sr)_(i)(0.70346 to 0.70505)and highεNd(t)values(4.6 to 6.8)of the P-type jadeitites and quartzites,along with relatively lowδ^(18)O values(4.7‰to 6.4‰)of their forming fluids,indicate that the fluids are likely derived from the altered basaltic crust rather than from oceanic sediment.However,the estimated jadeitite-and quartzite-forming fluids exhibit distinctδ^(30)Si values(0.76‰to 0.99‰and-0.48‰to-0.08‰,respectively),implying an evolution of the fluids that modified the Si isotopic compositions.Since fluid metasomatism and related desilication process could have lowered the whole-rock δ^(30)Si values,the heavy Si isotope compositions of the R-type samples are produced from the external fluids.Combing Rayleigh distillation and binary mixing simulations,we propose that fluids derived from altered oceanic crust obtained high δ^(30)Si values after crystallization of minerals enriched in light Si isotopes.The P-type jadeitites are formed through direct precipitation from this fluid.As the plagiogranite protoliths were continuously replaced by this fluid,the formed R-type samples(jadeitites and quartzites)also exhibit high δ^(30)Si values.Such rocks could significantly alter the Si isotope compositions of local mantle when they are deeply subducted at convergent plate margins.展开更多
Chinaʼs continental shale exhibits favorable geological characteristics and substantial resource potential,yet oil recovery for natural energy extraction remains critically low.Investigating the mechanisms of hydrauli...Chinaʼs continental shale exhibits favorable geological characteristics and substantial resource potential,yet oil recovery for natural energy extraction remains critically low.Investigating the mechanisms of hydraulically induced bedding fracture to generate complex fracture networks in continental shale,and establishing effective flow systems,is of utmost importance.This study employs laboratory experiments and numerical simulations to investigate the flow capacity and percolation behavior of hydraulically induced bedding fractures by different fluids in full-diameter shale cores.Hydraulic stimulation using different fluids generates bedding plane fracture networks,establishing effective flow systems.Eroded and detached shale fragments support localized fractures,thereby increasing their opening and enhancing flow capacity.Cetyltrimethylammonium bromide(CTAB)solution and SiO2 solution reduce the hydration of the shale surface,preventing shale fragments from swelling and disintegrating,leading to more stable percolation behavior.Eroded and spalled shale fragments near the injection point are transported to farther locations,where they help support localized fractures.This process differs from conventional hydraulic fracturing.Under a constant injection rate,the velocity in the smaller flow paths near the closure is significantly higher than that in the main flow paths,leading to pronounced bypass flow behavior.This restricts the percolation of fluid during imbibition in shale cores.The results provide valuable insights into the mechanism of hydraulically induced bedding fracture in continental shale,offering guidance for the effective development of shale reservoirs.展开更多
The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban margina...The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban marginal marine basin and the Junggar freshwater basin revealed significant isotope-geochemical differences due to various types of sedimentation.The waters from both basins exhibit three principal geochemical facies:Na-HCO_(3),Na-Cl-HCO_(3),and Na-Cl,of which the latter type of water is the dominant.The analysis of genetic coefficients(Cl/Br,Na/Br,and B/Cl)allowed us to distinguish different pathways of mud volcanic water evolution:evaporite dissolution,formation(sedimentation)waters,and waters formed by active water-rock interaction.Through statistical research,we were able to determine that noticeable variations in the behavior of chemical elements in waters from different areas can reflect discrepancies in the geological environment and the evolutionary stage of the diagenetic water transformation.Using thermodynamic modeling,the main directions of mass transfer were shown.It was established that the waters of the Junggar Basin were at a relatively early stage of evolution and had reached equilibrium only with carbonates,while in the formation waters of the West Kuban Basin,element concentrations were also controlled by silicate minerals.The correlations betweenδ^(18)O andδ~2H values and saturation indices of halides,aluminosilicates,sulfates,and borates confirm the enrichment of water with heavy isotopes during interactions with rocks without evaporation or thermal water partition.These reactions are characterized by clay dehydration and water enrichment with^(18)O and B.The data obtained made it possible to clarify the depths of formation of mud-volcanic fluids and their possible stratigraphic sources.展开更多
The Beijing-Tianjin-Hebei Plain is among the regions in China that feature the largest scale and the fastest growth in medium and deep geothermal heating.Based on tests of 82 geothermal fluid samples from 7 geothermal...The Beijing-Tianjin-Hebei Plain is among the regions in China that feature the largest scale and the fastest growth in medium and deep geothermal heating.Based on tests of 82 geothermal fluid samples from 7 geothermal fields in Hebei Province,2 geothermal fields in Henan Province,and 2 geothermal fields in Shandong Province,and combined with previous studies on the chemical characteristics of karst geothermal water in Beijing and Tianjin,this paper systematically analyzes the migration characteristics of geothermal fluids in karst geothermal reservoirs within the Beijing-Tianjin-Hebei Plain.The hydrochemical characteristics of karst geothermal water in the research areas exhibit certain differences.The geothermal water in Hebei is more mature than that in its neighboring provinces.The distribution of total dissolved solids(TDS)and strontium elements in the area is characterized by being low in the north and south and high in the middle,suggesting that the overall flow direction of geothermal fluid is from the north and south towards the middle.Combined with the groundwater flow field and the changing trend of the hydrochemical characteristics of geothermal wells along the geological section,a geothermal water migration model has been established.The geothermal fluids originating from Taihang Mountain,Yanshan Mountain,and Western Shandong Mountain enter the basin and continue to migrate towards the central part of the basin along water-conducting faults.However,the migration characteristics of geothermal fluids with the same supply direction are not identical.The geothermal fluids from Taihang Mountain are cut off by the Niudong Fault in the north and terminate in the central uplift belt of the Jizhong Depression,while in the south,they enter the east of the Jizhong Depression relatively quickly along the Hengshui Conversion Belt.The geothermal fluids from Yanshan Mountain migrate into the basin along the Cangdong Fault,yet this fault also disrupts the hydraulic connection between the tectonic units.Considering the effective dynamic conditions,it is recommended to further expand the scale of the scientific development and utilization of geothermal energy in the geothermal water catchment areas around Xiongxian County and southwest Cangzhou City.展开更多
Previous studies on post-fracturing flowback fluids focus primarily on their cleaning and discharge,high salinity sources,and damage to gas reservoirs.An analysis of the geochemical characteristics of these fluids hel...Previous studies on post-fracturing flowback fluids focus primarily on their cleaning and discharge,high salinity sources,and damage to gas reservoirs.An analysis of the geochemical characteristics of these fluids helps develop an improved understanding of the preservation condition and fracturing performance of shale gas reservoirs.This study analyzed the ion,total dissolved solids(TDS)concentration,and stable isotope characteristics of post-fracturing flowback fluids from five horizontal shale gas wells in the Luzhou area.Among these wells,two were subjected to hydraulic fracturing using fresh water,and three using reused flowback fluids.The results indicate that with increasing flowback time,the post-fracturing flowback fluids from wells subjected to hydraulic fracturing using fresh water showed increased TDS concentration,heavier stable isotopes,and the presence of new ion components.These results indicate the mixing of a large volume of formation water into the fluids.In contrast,postfracturing flowback fluids from wells subjected to hydraulic fracturing using reused flowback fluids exhibited a slow increase in the TDS concentration and stable isotopes.As the flowback time increased,the trends in TDS concentration and stable isotope ratios of post-fracturing flowback fluids from shale gas wells subjected to fracturing using fresh water evolved toward those of post-fracturing flowback fluids from shale gas wells undergoing fracturing using reused flowback fluids.Measurements show that post-fracturing flowback fluids from both well types exhibited roughly the same properties after one year of shale gas production.This result suggests that post-fracturing flowback fluids from wells using reused flowback fluids progressively took on the formation water properties.In particular,postfracturing flowback fluids from well Lu 211—a well subjected to hydraulic fracturing using fresh water—showed a low sodium-chloride coefficient,a low coefficient of variation,high TDS concentration,heavy stable isotopes,and a high nitrate ion concentration.This indicates a formation water source of the fluids and the poor sealing of the formation water,which hinders shale gas enrichment.The quantification of the fracturing fluid and formation water contents in the post-fracturing flowback fluids reveals that higher TDS concentration and heavier stable isotopes in the fluids appear to correspond to higher formation water content and lower fracturing fluid content,as well as higher fracturing performance.A systematic analysis of the geochemical characteristics and flowback pattern of fracturing fluids indirectly provides insights into the flow path of formation water,water body mixing,rock-water interactions,and fluid sources.Besides,the analysis offers a new perspective for understanding the preservation conditions and fracturing performance of shale gas reservoirs.展开更多
Microbial polysaccharides,due to their unique physicochemical properties,have been shown to effec-tively enhance the stability of foam fracturing fluids.However,the combined application of microbial polysaccharides an...Microbial polysaccharides,due to their unique physicochemical properties,have been shown to effec-tively enhance the stability of foam fracturing fluids.However,the combined application of microbial polysaccharides and surfactants under high-temperature and high-salinity conditions remain poorly understood.In this study,we innovatively investigate this problem with a particular focus on foam stabilization mechanisms.By employing the Waring blender method,the optimal surfactant-microbial polysaccharide blends are identified,and the foam stability,rheological properties,and decay behavior in different systems under varying conditions are systematically analyzed for the first time.The results reveal that microbial polysaccharides significantly enhance foam stability by improving the viscoelasticity of the liquid films,particularly under high-salinity and high-temperature conditions,leading to notable improvements in both foam stability and sand-carrying capacity.Additionally,scanning electron microscopy(SEM)is used to observe the microstructure of the foam liquid films,demonstrating that the network structure formed by the foam stabilizer within the liquid film effectively inhibits foam coarsening.The Lauryl betaine and Diutan gum blend exhibits outstanding foam stability,superior sand-carrying capacity,and minimal core damage,making(LAB+MPS04)it ideal for applications in enhanced production and reservoir stimulation of unconventional reservoirs.展开更多
This paper concerns the Cauchy problem of 3D compressible micropolar fluids in the whole space R^(3). For regular initial data with m0E0 is suitable small, where m0 and E0 represent the upper bound of initial density ...This paper concerns the Cauchy problem of 3D compressible micropolar fluids in the whole space R^(3). For regular initial data with m0E0 is suitable small, where m0 and E0 represent the upper bound of initial density and initial energy, we prove that if ρ0 ∈ Lγ ∩ H3 with γ ∈ (1, 6), then the problem possesses a unique global classical solution on R^(3) × [0, T] with any T ∈ (0, ∞). It’s worth noting that both the vacuum states and possible random largeness of initial energy are allowed.展开更多
As the global exploration and development of oil and gas resources advances into deep formations,the harsh conditions of high temperature and high salinity present significant challenges for drilling fluids.In order t...As the global exploration and development of oil and gas resources advances into deep formations,the harsh conditions of high temperature and high salinity present significant challenges for drilling fluids.In order to address the technical difficulties associated with the failure of filtrate loss reducers under high-temperature and high-salinity conditions.In this study,a hydrophobic zwitterionic filtrate loss reducer(PDA)was synthesized based on N,N-dimethylacrylamide(DMAA),2-acrylamido-2-methylpropane sulfonic acid(AMPS),diallyl dimethyl ammonium chloride(DMDAAC),styrene(ST)and a specialty vinyl monomer(A1).When the concentration of PDA was 3%,the FLAPI of PDA-WBDF was 9.8 mL and the FLHTHP(180℃,3.5 MPa)was 37.8 mL after aging at 240℃for 16 h.In the saturated NaCl environment,the FLAPI of PDA-SWBDF was 4.0 mL and the FLHTHP(180℃,3.5 MPa)was 32.0 mL after aging at 220℃ for 16 h.Under high-temperature and high-salinity conditions,the combined effect of anti-polyelectrolyte and hydrophobic association allowed PDA to adsorb on the bentonite surface tightly.The sulfonic acid groups of PDA increased the negative electronegativity and the hydration film thickness on bentonite surface,which enhanced the colloidal stability,maintained the flattened lamellar structure of bentonite and formed an appropriate particle size distribution,resulting in the formation of dense mud cakes and reducing the filtration loss effectively.展开更多
Multiphase flow in porous rock is of great importance in the application of many industrial processes,including reservoir delineation,enhanced oil recovery,and CO_(2) sequestration.However,previous research typically ...Multiphase flow in porous rock is of great importance in the application of many industrial processes,including reservoir delineation,enhanced oil recovery,and CO_(2) sequestration.However,previous research typically investigated the dispersive behaviors when rock saturated with single or two-phase fluids and conducted limited studies on three-phase immiscible fluids.This study investigated the seismic dispersion,attenuation,and reflection features of seismic waves in three-phase immiscible fluidsaturated porous rocks.First,we proposed the calculation formulas of effective fluid modulus and effective fluid viscosity of multiphase immiscible fluids by taking into account the capillary pressure,reservoir wettability,and relative permeability simultaneously.Then,we analysed the frequencydependent behaviors of three-phase immiscible fluid-saturated porous rock under different fluid proportion cases using the Chapman multi-scale model.Next,the seismic responses are analysed using a four-layer model.The results indicate that the relative permeability,capillary pressure parameter,and fluid proportions are all significantly affect dispersion and attenuation.Comparative analyses demonstrate that dispersion and attenuation can be observed within the frequency range of seismic exploration for a lower capillary parameter a3 and higher oil content.Seismic responses reveal that the reflection features,such as travel time,seismic amplitude,and waveform of the bottom reflections of saturated rock and their underlying reflections are significantly dependent on fluid proportions and capillary parameters.For validation,the numerical results are further verified using the log data and real seismic data.This numerical analysis helps to further understand the wave propagation characteristics for a porous rock saturated with multiphase immiscible fluids.展开更多
Addressing the critical challenges of viscosity loss and barite sag in synthetic-based drilling fluids(SBDFs)under high-temperature,high-pressure(HTHP)conditions,this study innovatively developed a hyperbranched amide...Addressing the critical challenges of viscosity loss and barite sag in synthetic-based drilling fluids(SBDFs)under high-temperature,high-pressure(HTHP)conditions,this study innovatively developed a hyperbranched amide polymer(SS-1)through a unique stepwise polycondensation strategy.By integrating dynamic ionic crosslinking for temperature-responsive rheology and rigid aromatic moieties ensuring thermal stability beyond 260℃,SS-1 achieves a molecular-level breakthrough.Performance evaluations demonstrate that adding merely 2.0 wt% SS-1 significantly enhances key properties of 210℃-aged SBDFs:plastic viscosity rises to 45 mPa⋅s,electrical stability(emulsion voltage)reaches 1426 V,and the sag factor declines to 0.509,outperforming conventional sulfonated polyacrylamide(S-PAM,0.531)by 4.3%.Mechanistic investigations reveal a trifunctional synergistic anti-sag mechanism involving electrostatic adsorption onto barite surfaces,hyperbranched steric hindrance,and colloid-stabilizing network formation.SS-1 exhibits exceptional HTHP stabilization efficacy,substantially surpassing S-PAM,thereby providing an innovative molecular design strategy and scalable solution for next-generation high-performance drilling fluid stabilizers.展开更多
基金jointly funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDA0430301)the National Natural Science Foundation of China(grant Nos.42130109,41973059)。
文摘The formation of copper deposits is closely related to hydrothermal processes.Understanding the migration of copper in hydrothermal fluids aids in reconstructing mineralization processes and deciphering deposit genesis.Copper primarily exists as Cu^(+)and Cu^(2+)in hydrothermal solutions,with redox conditions governing their interconversion.In chloride-rich geological fluids,Cu-Cl complexes are considered critical for copper transport.However,the specific types and valence transitions of Cu-Cl complexes under varying hydrothermal conditions remain poorly understood.This study employed in situ Raman spectroscopy to systematically analyze Cu+HCl and CuCl_(2)+K_(2)S_(2)O_(3)/H_(2) systems under saturated vapor pressure at 25-300℃,elucidating the effects of temperature,Cl^(-)concentration,and redox conditions on copper speciation.In the Cu^(+)HCl system,copper dissolved as monovalent Cu-Cl complexes.At high temperatures(>200℃),[CuCl_(2)]^(-)is the dominated species,whereas[CuCl_(3)]^(2-)becomes prevalent at lower temperatures and higher HCl concentrations.For the Cu^(2+)-Cl system,the dominant species transitioned from[Cu(H_(2)O)n]^(2+)(<50℃)to[CuCl_(4)]^(2-)(100℃)and further to[CuCl]^(+)and[CuCl_(2)]^(0) at 300℃.The introduction of reducing agents(K_(2)S_(2)O_(3)/H_(2))facilitated Cu^(2+)→Cu^(+)reduction,thereby stabilizing Cu^(+)-Cl complexes and inducing partial copper precipitation.The behavior of copper in chloriderich hydrothermal fluids observed in this study indicates that high-temperature oxidizing fluids facilitate Cu mobilization,while cooling and redox changes promote deposition and ore minerals formation.
基金funded by National Natural Science Foundation of China(42373033,Yicheng Sun)Fundamental Research Funds for the Central Universities(B240201111,Yicheng Sun)。
文摘Supercritical fluids play a crucial role in material transport within Earth's deep interior.Investigating the pressure-dependent atomic structures and transport properties of such fluids is essential for understanding their petrological,chemical,and geophysical behaviors.In this study,we employed first-principles molecular dynamics simulations to explore the structures,self-diffusion coefficients(D),and viscosities(η)of supercritical NaAlSi_(3)O_(8)-H_(2)O fluids under conditions of 2000 K and 3-10 GPa,with water contents of 30 wt% and 50 wt%.Our calculations indicate that at a water content of 30 wt%,Q^(2) and Q^(3) exhibit a certain degree of positive and negative pressure dependence,respectively,while other Q^(n) species(n represents the number of bridging oxygens connected to Si/Al)show minimal changes.At a water content of 50 wt%,Q^(2) and Q^(0) exhibit a certain degree of positive and negative pressure dependence,respectively,while other Q^(n) species show minimal changes.At both water contents,Si-O-H and molecular water in the system exhibit negative pressure dependence,suggesting that the migration of supercritical fluids from deep to shallow regions is accompanied by the release of water.The self-diffusion coefficients in the supercritical NaAlSi_(3)O_(8)-H_(2)O fluid follow the order D_(Na)≈D_(H)>D_(O)>D_(Al)≈D_(Si),with an overall weak negative pressure dependence.By comparing the viscosities of anhydrous and hydrous silicate melts from previous studies,we found that the addition of water caused a transition from negative to positive pressure dependence of viscosity,corresponding to a structural change from polymerization to depolymerization.Additionally,we calculated the fluid mobility Δp/η of supercritical NaAlSi_(3)O_(8)-H_(2)O fluids and found that their mobility is several orders of magnitude higher than that of basalt melt and is also significantly greater than that of carbonate melt.As supercritical fluids ascend from deeper to shallower regions,their mobility is further enhanced,significantly contributing to the transport of elements from subducting slabs to the overlying mantle wedge.
基金Project supported by the National Natural Science Foundation of China(No.12525202)。
文摘Transcritical and supercritical fluids widely exist in aerospace propulsion systems,such as the coolant flow in the regenerative cooling channels of scramjet engines.To numerically simulate the coolant flow,we must address the challenges in solving Riemann problems(RPs)for real fluids under complex flow conditions.In this study,an exact numerical solution for the one-dimensional RP of two-parameter fluids is developed.Due to the comprehensive resolution of fluid thermodynamics,the proposed solution framework is suitable for all forms of the two-parameter equation of state(EoS).The pressure splitting method is introduced to enable parallel calculation of RPs across multiple grid points.Theoretical analysis demonstrates the isentropic nature of weak waves in two-parameter fluids,ensuring that the same mathematical properties as ideal gas could be applied in Newton's iteration.A series of numerical cases validate the effectiveness of the proposed method.A comparative analysis is conducted on the exact Riemann solutions for the real fluid EoS,the ideal gas EoS,and the improved ideal gas EoS under supercritical and transcritical conditions.The results indicate that the improved one produces smaller errors in the calculation of momentum and energy fluxes.
基金financed by Yunnan Major Scientific and Technological Projects(Grant No.202202AG050006)the National Natural Science Foundation of China(Grant No.42462011)Projects of Yunnan Province Technology Hall(Grant No.202305AT350004).
文摘The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified in the region via exploration.However,metallogenic sources and evolution of W remain unclear,and the existing metallogenic model has to be updated to guide further ore prospecting.Elemental and Sr-Nd isotopic data for scheelites assist in the determination of sources and evolution of the W-mineralizing fluids and metals in the district.Based on field geological survey,the scheelites in the Gejiu district can be categorized into three types:altered granite(Type Ⅰ),quartz vein(Type Ⅱ)from the Laochang deposit,and skarn(Type Ⅲ)from the Kafang deposit.Types Ⅰ and Ⅱ scheelites have low molybdenum(Mo)and strontium(Sr)contents,and Type Ⅱ scheelite has lower Sr contents than Type Ⅰ as well as higher Mo and Sr contents than Type Ⅲ scheelites.Varying Mo contents across the scheelite types suggests that the oxygen fugacity varied during ore accumulation.Type Ⅰ and Type Ⅱ scheelites exhibit similar rare earth elements(REE)patterns;Type Ⅲ scheelite contains lower REE content,particularly HREE,compared with the other scheelites.All scheelites exhibit negative Eu anomalies in the chondrite-normalized REE patterns.As the W-mineralization and two-mica granite share close spatial and temporal relationships,the negative Eu anomalies were likely inherited from the two-mica granite.Type Ⅰ and Type Ⅱ scheelites display varied(^(87)Sr/^(86)Sr)_(82 Ma)(0.7090-0.7141)andε_(Nd)(82 Ma)(from−9.9 to−5.4)values,similar to those of granite.However,Type Ⅲ scheelite exhibits lower(^(87)Sr/^(86)Sr)_(82 Ma)(0.7083-0.7087)and lowerε_(Nd)(82 Ma)(from−10.5 to−6.9)values than the two-mica granite.This indicates that the two-mica granite alone did not provide the ore-forming fluids and metals and that the Type Ⅲ scheelite ore-forming fluids likely involved external fluids that were probably derived from carbonate rocks.The implication is that highly differentiated two-mica granites were the source of primary W-bearing metals and fluids,which is consistent with earlier research on the origin of Sn ore-forming materials.
基金the financial support from the National Science and Technology Major Project of China(2024XXXXX2700)the National Natural Science Foundation of China (22408099)+1 种基金the Key Research and Development Program of Xinjiang Uygur Autonomous Region (2022B01032)the National Ten Thousand Talents Program。
文摘This study presents a theoretical and experimental analysis of laminar flow behavior of high-viscous non-Newtonian power-law and Bingham fluids in multiple structural bifurcation channel distributors.Theoretical models are derived to describe velocity profiles,shear rate distribution,and pressure drop across specific channels.Modified pressure drop models are proposed based on experiments on 6 kinds of non-Newtonian fluids and 3 types of bifurcation channel distributors with different transition areas.Specifically,the deviations between the theoretical models and the experimental results are systematically analyzed,and models were modified with correction coefficients based on Reynolds number and dimensionless shape factor.The theoretical results,modified results and experimental data are compared and discussed to ensure the accuracy of the modified models,demonstrating a significant improvement in the prediction of pressure drops for high-viscous non-Newtonian fluids in certain types of bifurcation channels.Additional experiments and analyses were carried out to validate the modified models and the results suggest that the models offer a certain degree of universal applicability in bifurcation channel designs.It implies that for other types of bifurcation channel distributors,similar correction methods based on Reynolds number and shape factor may also be applicable even with different coefficients.
基金financially supported by the Key Technologies R&D Program of China National Offshore Oil Corporation(No.KJGG2021-0504)。
文摘Understanding the thermodynamic behavior of complex fluids in confined environments is critical for various industrial and natural processes including but not limited to polymer flooding enhanced oil recovery(EOR).In this work,we develop Atif-V2.0,an extended classical density functional theory(cDFT)framework that integrates the interfacial statistical associating fluid theory(iSAFT)to model multicomponent associating fluids composed of water-soluble polymers,alkanes,and water.Building on the original theoretical framework of Atif for modeling nanoconfined inhomogeneous fluids,Atif-V2.0 embeds explicit solvent and captures additional physical interactions-hydrogen bonding,which are critical in associating fluid systems.The other key feature of Atif-V2.0 is its ability to account for polymer topology.We demonstrate its capability by predicting the equilibrium structure and thermodynamic behavior of branched hydrolyzed polyacrylamide solutions near hard walls with various branching topologies,which provides a robust theoretical tool for the rational design of EOR polymers.
基金supported by Tarim Oilfield Project“Study on Formation Characteristics and Technical Countermeasures of Drilling Fluid in Yingsha and Yulong Blocks”(Project No.201019121044)the National Natural Science Foundation of China(ZX20200280).
文摘Aiming at the leakage problem in the compact sandstone drilling of the Keziluoyi Formation in South-west Tarim,Nano-core-emulsion was prepared by coating modified nano-SiO_(2) with nano-emulsion,its particle size D50 is about 100 nm,with good dispersion stability.When 0.8%Nano-core-emulsion is added to 5%bentonite slurry,the fluid loss can be reduced by 40%,and the filter cake thickness can be reduced by 84%.Using a Nano-core-emulsion to optimize the plugging performance of potassium pol-ysulfonate drilling fluid can reduce the fluid loss of the drilling fluid by 52%,the resulting filter cake is dense and tough,and the thickness is reduced by 40%.Using the pressure conduction method to evaluate the plugging rate,the plugging rate of the drilling fluid of the Nano-core-emulsion on the core of the Keziluoyi Formation is 63.4%,which is 20.9%higher than that of the field drilling fluid.According to microscopic examination and CT scanning analysis,the material has the plugging characteristics of"inner rigid support+outer soft deformation"and has demonstrated good field application results.
基金supported by the National Natural Science Foundation of China(22078009)National Key Research Program of China(2021YFC3001102,2021YFC3001100).
文摘Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs.In this study,the micromixing efficiency in MCRs was experimentally investigated using CMC(carboxymethyl cellulose sodium)aqueous solution to simulate a non-Newtonian fluid,and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics(CFD)simulations.The results show that in the conventional channel,increasing the flow rate improves the micromixing efficiency when the CMC concentration is low.However,when the CMC concentration is higher,the higher the flow rate,the lower the micromixing efficiency.The highest micromixing efficiency is obtained for the rotationally coupled inner components,followed by the single rotation and the lowest is for the internals only.CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor,which effectively reduces the apparent viscosity.These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.
基金Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering(Yangtze University),China(Grant No.YQZC202415)Hubei Province Science and Technology Plan Project(Key R&D Special Project),China(Grant No.2023BCB070)+2 种基金Key R&D Program Project in Xinjiang,China,Grant No.2022B01042Guiding Project of Scientific Research Program of Education Department of Hubei Province,China(Grant No.B2023024)Open Fund of National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University),Grant No.PLN2023-03.
文摘Drilling operations in carbonate rock heavy oil blocks(e.g.,in the Tahe Oilfield)are challenged by the intrusion of high-viscosity,temperature-sensitive formation heavy oil into the drilling fluid.This phenomenon often results in wellbore blockage,reduced penetration rates,and compromised well control,thereby significantly limiting drilling efficiency and operational safety.To address this issue,this study conducts a comprehensive investigation into the mechanisms governing heavy oil invasion using a combination of laboratory experiments and field data analysis.Findings indicate that the reservoir exhibits strong heterogeneity and that the heavy oil possesses distinctive physical properties.The intrusion process is governed by multiple interrelated factors,including pressure differentials,pore structure,and the rheological behavior of the heavy oil.Experimental results reveal that the invasion of heavy oil occurs in distinct phases,with temperature playing a critical role in altering its viscosity.Specifically,as temperature increases,the apparent viscosity of the drilling fluid decreases;however,elevated pressures induce a nonlinear increase in viscosity.Furthermore,the compatibility between the drilling fluid and the intruding heavy oil declines markedly with increasing oil concentration,substantially raising the risk of wellbore obstruction.Simulation experiments further confirm that at temperatures exceeding 40℃and injection rates of L/min,the likelihood of wellbore blockage significantly≥0.4increases due to heavy oil infiltration.Based on these insights,a suite of targeted mitigation strategies is proposed.These include the formulation of specialized chemical additives,such as viscosity reducers,dispersants,and plugging removal agents,the real-time adjustment of drilling fluid density,and the implementation of advanced monitoring and early-warning systems.
基金supported by the National Natural Science Foundation of China(Grant No.11672182).
文摘Self-propulsion of a deformable ellipse immersed in an unbounded inviscid fluid is discussed in order to explore the effect of the deformation and controlled rotation of the body coupled with the shift of its internal mass on the self-motion.The ellipse is capable of symmetric deformation along the two orthogonal axes and endowed with some self-regulation ability via the shift and rotation of its internal mass.From the model,the appropriate velocity potential induced by the motion of the ellipse with the deformation in an otherwise undisturbed fluid is derived,and then the equations of motion are obtained by means of integrals of the unsteady fluid pressure.The equations are utilized to explore self-translational behaviors of the ellipse through the cyclic shift of its internal mass and deformation coupled with its own controllable rotation.Analysis and numerical results show that the ellipse can break the kinematic time-reversal symmetry by properly adjusting its own rotation to coordinate with the deformation and the cyclic shift of the inner mass to meet a forward criterion,and push itself to move persistently forward without a regression at zero system momentum,exhibiting some basic serpentine movements according as the ellipse performs complete revolutions or oscillates between two extreme yaw angles during its self-motion.
基金supported by funds from the National Key Research and Development Program of China(Grant No.2024YFF0807302)National Natural Science Foundation of China(42273043,42173003)the International Visiting Professorship of USTC(2024BVR23).
文摘Jadeitites are formed either through direct precipitation from Na-Al-Si rich fluids(P-type),or by replacement of magmatic protoliths(R-type)in subduction zones.They are valuable targets for investigating the mobility behavior and chemical composition of subduction zone fluids.The Rio San Juan Complex(RSJC)in the northern Dominican Republic hosts both P-and R-type jadeitites and jadeite-rich rocks,which provide ideal samples for addressing such issues.Here,we present trace element and Sr-Nd-O-Si isotope compositions of RSJC jadeitites and related rocks.Most samples show similar REE patterns,trace element distributions and δ^(18)O values to those of plagiogranite protoliths,indicating the predominance of R-type origin in RSJC.The P-type samples exhibit slightly higherδ^(30)Si values(−0.15‰to 0.25‰)than that of R-type samples(−0.20‰to 0.08‰),which place above the igneous array.The low(^(87)Sr/^(86)Sr)_(i)(0.70346 to 0.70505)and highεNd(t)values(4.6 to 6.8)of the P-type jadeitites and quartzites,along with relatively lowδ^(18)O values(4.7‰to 6.4‰)of their forming fluids,indicate that the fluids are likely derived from the altered basaltic crust rather than from oceanic sediment.However,the estimated jadeitite-and quartzite-forming fluids exhibit distinctδ^(30)Si values(0.76‰to 0.99‰and-0.48‰to-0.08‰,respectively),implying an evolution of the fluids that modified the Si isotopic compositions.Since fluid metasomatism and related desilication process could have lowered the whole-rock δ^(30)Si values,the heavy Si isotope compositions of the R-type samples are produced from the external fluids.Combing Rayleigh distillation and binary mixing simulations,we propose that fluids derived from altered oceanic crust obtained high δ^(30)Si values after crystallization of minerals enriched in light Si isotopes.The P-type jadeitites are formed through direct precipitation from this fluid.As the plagiogranite protoliths were continuously replaced by this fluid,the formed R-type samples(jadeitites and quartzites)also exhibit high δ^(30)Si values.Such rocks could significantly alter the Si isotope compositions of local mantle when they are deeply subducted at convergent plate margins.
基金supported by the Frontier and Fundamental Research of Active Nanofluids Flooding for Enhanced Oil Recovery through Discontinuous and Variable-circle Modes in High Temperature and High Salinity Offshore Oilfields(U22B6005)National Natural Science Foundation of China(No.52274037)Study on Key Issues of Enhanced Oil Recovery of Gulong Shale Oil(DQYT-2022-JS-761).
文摘Chinaʼs continental shale exhibits favorable geological characteristics and substantial resource potential,yet oil recovery for natural energy extraction remains critically low.Investigating the mechanisms of hydraulically induced bedding fracture to generate complex fracture networks in continental shale,and establishing effective flow systems,is of utmost importance.This study employs laboratory experiments and numerical simulations to investigate the flow capacity and percolation behavior of hydraulically induced bedding fractures by different fluids in full-diameter shale cores.Hydraulic stimulation using different fluids generates bedding plane fracture networks,establishing effective flow systems.Eroded and detached shale fragments support localized fractures,thereby increasing their opening and enhancing flow capacity.Cetyltrimethylammonium bromide(CTAB)solution and SiO2 solution reduce the hydration of the shale surface,preventing shale fragments from swelling and disintegrating,leading to more stable percolation behavior.Eroded and spalled shale fragments near the injection point are transported to farther locations,where they help support localized fractures.This process differs from conventional hydraulic fracturing.Under a constant injection rate,the velocity in the smaller flow paths near the closure is significantly higher than that in the main flow paths,leading to pronounced bypass flow behavior.This restricts the percolation of fluid during imbibition in shale cores.The results provide valuable insights into the mechanism of hydraulically induced bedding fracture in continental shale,offering guidance for the effective development of shale reservoirs.
基金partly supported by the NSFC-RSF Joint Research project(Nos.42261134534,23-47-00035)funded by the Chinese Academy of Sciences President’s International Fellowship Initiative(Nos.2024VCA0006,2024VCB0013)the National Natural Science Foundation of China(No.42442006)。
文摘The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban marginal marine basin and the Junggar freshwater basin revealed significant isotope-geochemical differences due to various types of sedimentation.The waters from both basins exhibit three principal geochemical facies:Na-HCO_(3),Na-Cl-HCO_(3),and Na-Cl,of which the latter type of water is the dominant.The analysis of genetic coefficients(Cl/Br,Na/Br,and B/Cl)allowed us to distinguish different pathways of mud volcanic water evolution:evaporite dissolution,formation(sedimentation)waters,and waters formed by active water-rock interaction.Through statistical research,we were able to determine that noticeable variations in the behavior of chemical elements in waters from different areas can reflect discrepancies in the geological environment and the evolutionary stage of the diagenetic water transformation.Using thermodynamic modeling,the main directions of mass transfer were shown.It was established that the waters of the Junggar Basin were at a relatively early stage of evolution and had reached equilibrium only with carbonates,while in the formation waters of the West Kuban Basin,element concentrations were also controlled by silicate minerals.The correlations betweenδ^(18)O andδ~2H values and saturation indices of halides,aluminosilicates,sulfates,and borates confirm the enrichment of water with heavy isotopes during interactions with rocks without evaporation or thermal water partition.These reactions are characterized by clay dehydration and water enrichment with^(18)O and B.The data obtained made it possible to clarify the depths of formation of mud-volcanic fluids and their possible stratigraphic sources.
基金support received from the National Major Special Project titled“Exploration and Evaluation of Deep Geothermal Energy in Key Regions”(Project No.2024ZD1003600)the Science and Technology Department of Sinopec(Project No.JP24071).
文摘The Beijing-Tianjin-Hebei Plain is among the regions in China that feature the largest scale and the fastest growth in medium and deep geothermal heating.Based on tests of 82 geothermal fluid samples from 7 geothermal fields in Hebei Province,2 geothermal fields in Henan Province,and 2 geothermal fields in Shandong Province,and combined with previous studies on the chemical characteristics of karst geothermal water in Beijing and Tianjin,this paper systematically analyzes the migration characteristics of geothermal fluids in karst geothermal reservoirs within the Beijing-Tianjin-Hebei Plain.The hydrochemical characteristics of karst geothermal water in the research areas exhibit certain differences.The geothermal water in Hebei is more mature than that in its neighboring provinces.The distribution of total dissolved solids(TDS)and strontium elements in the area is characterized by being low in the north and south and high in the middle,suggesting that the overall flow direction of geothermal fluid is from the north and south towards the middle.Combined with the groundwater flow field and the changing trend of the hydrochemical characteristics of geothermal wells along the geological section,a geothermal water migration model has been established.The geothermal fluids originating from Taihang Mountain,Yanshan Mountain,and Western Shandong Mountain enter the basin and continue to migrate towards the central part of the basin along water-conducting faults.However,the migration characteristics of geothermal fluids with the same supply direction are not identical.The geothermal fluids from Taihang Mountain are cut off by the Niudong Fault in the north and terminate in the central uplift belt of the Jizhong Depression,while in the south,they enter the east of the Jizhong Depression relatively quickly along the Hengshui Conversion Belt.The geothermal fluids from Yanshan Mountain migrate into the basin along the Cangdong Fault,yet this fault also disrupts the hydraulic connection between the tectonic units.Considering the effective dynamic conditions,it is recommended to further expand the scale of the scientific development and utilization of geothermal energy in the geothermal water catchment areas around Xiongxian County and southwest Cangzhou City.
基金supported by China National Petroleum Corporation(NO:2023ZZ21)。
文摘Previous studies on post-fracturing flowback fluids focus primarily on their cleaning and discharge,high salinity sources,and damage to gas reservoirs.An analysis of the geochemical characteristics of these fluids helps develop an improved understanding of the preservation condition and fracturing performance of shale gas reservoirs.This study analyzed the ion,total dissolved solids(TDS)concentration,and stable isotope characteristics of post-fracturing flowback fluids from five horizontal shale gas wells in the Luzhou area.Among these wells,two were subjected to hydraulic fracturing using fresh water,and three using reused flowback fluids.The results indicate that with increasing flowback time,the post-fracturing flowback fluids from wells subjected to hydraulic fracturing using fresh water showed increased TDS concentration,heavier stable isotopes,and the presence of new ion components.These results indicate the mixing of a large volume of formation water into the fluids.In contrast,postfracturing flowback fluids from wells subjected to hydraulic fracturing using reused flowback fluids exhibited a slow increase in the TDS concentration and stable isotopes.As the flowback time increased,the trends in TDS concentration and stable isotope ratios of post-fracturing flowback fluids from shale gas wells subjected to fracturing using fresh water evolved toward those of post-fracturing flowback fluids from shale gas wells undergoing fracturing using reused flowback fluids.Measurements show that post-fracturing flowback fluids from both well types exhibited roughly the same properties after one year of shale gas production.This result suggests that post-fracturing flowback fluids from wells using reused flowback fluids progressively took on the formation water properties.In particular,postfracturing flowback fluids from well Lu 211—a well subjected to hydraulic fracturing using fresh water—showed a low sodium-chloride coefficient,a low coefficient of variation,high TDS concentration,heavy stable isotopes,and a high nitrate ion concentration.This indicates a formation water source of the fluids and the poor sealing of the formation water,which hinders shale gas enrichment.The quantification of the fracturing fluid and formation water contents in the post-fracturing flowback fluids reveals that higher TDS concentration and heavier stable isotopes in the fluids appear to correspond to higher formation water content and lower fracturing fluid content,as well as higher fracturing performance.A systematic analysis of the geochemical characteristics and flowback pattern of fracturing fluids indirectly provides insights into the flow path of formation water,water body mixing,rock-water interactions,and fluid sources.Besides,the analysis offers a new perspective for understanding the preservation conditions and fracturing performance of shale gas reservoirs.
基金supported by the Key Technology Research on Increasing Recovery Rate in Tight Sandstone Gas Reservoirs,a Major Scientific and Technological Special Project of China National Petroleum Corporation(Project No.2023ZZ25).
文摘Microbial polysaccharides,due to their unique physicochemical properties,have been shown to effec-tively enhance the stability of foam fracturing fluids.However,the combined application of microbial polysaccharides and surfactants under high-temperature and high-salinity conditions remain poorly understood.In this study,we innovatively investigate this problem with a particular focus on foam stabilization mechanisms.By employing the Waring blender method,the optimal surfactant-microbial polysaccharide blends are identified,and the foam stability,rheological properties,and decay behavior in different systems under varying conditions are systematically analyzed for the first time.The results reveal that microbial polysaccharides significantly enhance foam stability by improving the viscoelasticity of the liquid films,particularly under high-salinity and high-temperature conditions,leading to notable improvements in both foam stability and sand-carrying capacity.Additionally,scanning electron microscopy(SEM)is used to observe the microstructure of the foam liquid films,demonstrating that the network structure formed by the foam stabilizer within the liquid film effectively inhibits foam coarsening.The Lauryl betaine and Diutan gum blend exhibits outstanding foam stability,superior sand-carrying capacity,and minimal core damage,making(LAB+MPS04)it ideal for applications in enhanced production and reservoir stimulation of unconventional reservoirs.
基金supported by the Natural Science Foundation of Shandong Province of China(ZR2024MA033ZR2021QA049).
文摘This paper concerns the Cauchy problem of 3D compressible micropolar fluids in the whole space R^(3). For regular initial data with m0E0 is suitable small, where m0 and E0 represent the upper bound of initial density and initial energy, we prove that if ρ0 ∈ Lγ ∩ H3 with γ ∈ (1, 6), then the problem possesses a unique global classical solution on R^(3) × [0, T] with any T ∈ (0, ∞). It’s worth noting that both the vacuum states and possible random largeness of initial energy are allowed.
基金supported by State Key Laboratory of Deep Oil and Gas(No.SKLDOG2024-ZYRC-03)supported by the Excellent Young Scientists Fund of the National Natural Science Foundation of China(No.52322401)the National Natural Science Foundation of China(52288101).
文摘As the global exploration and development of oil and gas resources advances into deep formations,the harsh conditions of high temperature and high salinity present significant challenges for drilling fluids.In order to address the technical difficulties associated with the failure of filtrate loss reducers under high-temperature and high-salinity conditions.In this study,a hydrophobic zwitterionic filtrate loss reducer(PDA)was synthesized based on N,N-dimethylacrylamide(DMAA),2-acrylamido-2-methylpropane sulfonic acid(AMPS),diallyl dimethyl ammonium chloride(DMDAAC),styrene(ST)and a specialty vinyl monomer(A1).When the concentration of PDA was 3%,the FLAPI of PDA-WBDF was 9.8 mL and the FLHTHP(180℃,3.5 MPa)was 37.8 mL after aging at 240℃for 16 h.In the saturated NaCl environment,the FLAPI of PDA-SWBDF was 4.0 mL and the FLHTHP(180℃,3.5 MPa)was 32.0 mL after aging at 220℃ for 16 h.Under high-temperature and high-salinity conditions,the combined effect of anti-polyelectrolyte and hydrophobic association allowed PDA to adsorb on the bentonite surface tightly.The sulfonic acid groups of PDA increased the negative electronegativity and the hydration film thickness on bentonite surface,which enhanced the colloidal stability,maintained the flattened lamellar structure of bentonite and formed an appropriate particle size distribution,resulting in the formation of dense mud cakes and reducing the filtration loss effectively.
基金supported in part by the National Natural Science Foundation of China under Grant 41874143 and Grant 42374163in part by the Key Program of Natural Science Foundation of Sichuan Province of China under Grant 2023NSFSC0019in part by the Central Funds Guiding the Local Science and Technology Development under Grant 2024ZYD0124.
文摘Multiphase flow in porous rock is of great importance in the application of many industrial processes,including reservoir delineation,enhanced oil recovery,and CO_(2) sequestration.However,previous research typically investigated the dispersive behaviors when rock saturated with single or two-phase fluids and conducted limited studies on three-phase immiscible fluids.This study investigated the seismic dispersion,attenuation,and reflection features of seismic waves in three-phase immiscible fluidsaturated porous rocks.First,we proposed the calculation formulas of effective fluid modulus and effective fluid viscosity of multiphase immiscible fluids by taking into account the capillary pressure,reservoir wettability,and relative permeability simultaneously.Then,we analysed the frequencydependent behaviors of three-phase immiscible fluid-saturated porous rock under different fluid proportion cases using the Chapman multi-scale model.Next,the seismic responses are analysed using a four-layer model.The results indicate that the relative permeability,capillary pressure parameter,and fluid proportions are all significantly affect dispersion and attenuation.Comparative analyses demonstrate that dispersion and attenuation can be observed within the frequency range of seismic exploration for a lower capillary parameter a3 and higher oil content.Seismic responses reveal that the reflection features,such as travel time,seismic amplitude,and waveform of the bottom reflections of saturated rock and their underlying reflections are significantly dependent on fluid proportions and capillary parameters.For validation,the numerical results are further verified using the log data and real seismic data.This numerical analysis helps to further understand the wave propagation characteristics for a porous rock saturated with multiphase immiscible fluids.
