Abstract: Based on the latest data of deep petroleum accumulations,this study aims at documenting distribution patterns and geological features of global siliciclastic reservoirs. Central South America and North America(excluding the Lower 48 States) host the largest shares of the total proved and probable(2P) oil and gas reserves in deep siliciclastic rocks. North America contains the bulk of 2P oil reserves in deep siliciclastic rocks,whereas Central South America has the lion's share of gas and condensate reserves. Of all deep petroliferous basins with siliciclastic reservoirs,the 6 most prolific basins are the Gulf of Mexico,East Venezuela,Arabian,South Caspian,Tarim and Santa Cruz-Tarija Basins. Deep siliciclastic reservoirs are generally characterized by poor petrophysics. It is fair to say,however,that high-quality sandstone reservoirs could be developed under favorable geological conditions at deep burials.The key of deep petroleum exploration is the better delineation of "Sweet Spots" in deep layers where grain coatings,fluid overpressure and/or well-developed salts might have preserved the considerable portion of original primary porosity.
Abstract: Taking a composite system of casing-cement sheath-formation in a high temperature and high pressure oil well as the research object,a thermo-structural coupling model is constructed and its theoretical solution is obtained by considering contact,continuity and boundary conditions. The theoretical solution is very accurate in comparison with FEM solution. Comparing the theoretical solutions with thermo-structural coupling effects and without thermal load,it is indicated that thermal load has much greater influence on the equivalent stress. Failure coefficient,which is used to analyze structure integrity,is defined by Mises,Drucker-Prager and Mohr-Coulomb yield criteria. The factors of elastic modulus,Poisson's ratio,nonuniform in-situ stress coefficient,formation temperature and casing pressure are discussed by considering the failure coefficient distribution of casing-cement sheath formation. The results show that the above factors have great effect on the failure coefficient distribution. The failure coefficient of the 1st cementation plane is greater than that of other planes and its influence on wellbore integrity is large.
Abstract: Two-hole blasting of jointed rock mass under different in-situ stress conditions(lateral pressure coefficient:0.5,1 and 2; vertical stress:5 MPa and 10 MPa) and joint angles(30°,45°,60° and 90°) was numerically simulated to study the process of crack initiation,propagation and coalescence. In the simulation,rock damage was induced by stress waves and explosion gas pressure. Simulation results indicate that for rock without a joint,the initial stress field has a guide role on crack propagation,and the crack propagation direction coincides with the maximum compressive principal stress. However,the existing joint has effect on the crack propagation direction. When the joint angle is 30°,the blasting induced crack connects with the joint and forms a "z" shape.The existing joint would play a positive role in promoting crack initiation and propagation and favor crack propagation along the vertical direction.
Abstract: The effects of reductant type and dosage on the reduction roasting and Fe-P separation of high phosphorus oolictic hematite were studied in this paper. Experimental results show that,with addition of Na2CO3 as a dephosphorization agent,the iron content increases,the phosphorus content decreases in direct reduced iron,and the sulfur content can be decreased at the same time.Iron reduction is promoted by increasing the reductant dosage,but reductants with higher ash and fixed carbon contents or a lower volatile content do not favor dephosphorization. X-ray diffraction analyses of roasted products indicate that Na2CO3 as a dephosphorization agent is added in reduction roasting,the content of metallic iron increases but the contents of wustite and quartz decrease with increasing reductant dosage. When using a reductant with a higher ash content,Na2CO3 can be consumed by the ash with increasing reductant dosage,thus its promotion to iron reduction weakens. At the same reductant dosage,the highest content of metallic iron in roasted products is obtained by using stone coal as a reductant,followed by bituminous coal,coke and lignite,and the content of wustite in roasted products gradually decreases. As a whole,there is the best Fe-P separation effect in this iron ore treatment by using lignite as a reductant,followed by bituminous coal,coke and stone coal.
Abstract: The differences in shape correction coefficient(SCC) of common inclusions in molten steel including spherical,cubic,cylindrical,dendritic and cluster particles were studied by a physical simulation method. The effects of inclusion surface morphologies and movement orientation on the SCC were analyzed on the basis of simulation results. The SCC can be used to evaluate the inclusion removal ability because of a linear correlation relationship between the SCC and the resistance coefficient of inclusions. For inclusions with the same volume but different shapes,the removal ability increase in order as follows:dendritic particles with vertical floatation,spherical particles with coarse surfaces,cubic particles,cylindrical particles of 6 mm in radium,cylindrical particles of 4 mm in radium,dendritic particles with horizontal floatation,clusters,and spherical particles with smooth surfaces. When the surface area of spherical particles with coarse surfaces is approximately 2 times as large as that of spherical particles with smooth surfaces,the SCC of spherical particles with coarse surfaces increases by 2.1 times compared with the smooth ones. For simple particles,movement orientation has just limited effect on the SCC,but it influences the SCC of complex particles greatly. The SCC of dendritic particles with vertical floatation is about twice of that with horizontal floatation.
Abstract: The residence time distribution(RTD) obtained from a pulse tracer experiment is always used for characterizing the flow fluid in tundishes. However,it is not suit to multi-strand or asymmetric tundishes because of negative volume or deviations calculated by the typical combined model using the RTD. In this paper,the accumulated residence time distribution(F curve) obtained from a step tracer experiment is applied to dead volume and plug volume calculations. This method is appropriate for single-strand tundishes and multi-strand tundishes. In this way,a 7-strand tundish in a steel plant is studied for optimizing its flow control devices.In the end,the dead volume decreases,and the distribution of molten steel among the strands tends to uniform,which benefits the slab quality and production process.
Abstract: A mathematical model of particle growth taking nonlinear temperature-depended interface kinetics into account was investigated,and the particle interface evolution and morphological stability were analyzed. The asymptotic solution of particle growth and the change rate of interface perturbations were obtained by means of an asymptotic expansion method. The result shows that the interface kinetics undercooling and the particle growth velocity decrease with increasing interface kinetics,and that the nonlinear temperature-depended interface kinetics tends to stabilize particle growth. Compared with the situation of neglecting interfacial kinetics,the nonlinear interfacial kinetics significantly decreases the particle growth velocity.
Abstract: To research the static recrystallization behavior of high strength steel 300 M,single/double-pass hot compression tests of 300 M steel were carried out using Gleeble-3800 thermal simulation experiment equipment. The effects of deformation temperature,strain rate,height reduction and initial grain size on the volume fraction of static recrystallization were analyzed by double-pass hot compression tests. It is found that the volume fraction of static recrystallization rapidly increases with increasing deformation temperature,strain rate or height reduction,while it decreases with increasing initial grain size. Initial grain size has less effect than the others. A static recrystallization volume fraction model and a completely static recrystallization grain size model of 300 M steel were established based on the results of double-pass and single-pass hot compression tests,respectively,and the static recrystallization volume fraction model was verified to be correct by single-pass hot compression tests.
Abstract: The effects of Mn on the microstructure morphology,phase transformation and mechanical properties of medium manganese wear resistant steel were investigated by DIL805 A thermal analyzer,scanning electron microscopy,electron back-scattered diffraction,transmission electron microscopy and mechanical testing. When the mass fraction of Mn increases from 3% to 9% by a 2%increment,the volume fraction of austenite at room temperature gradually increases. The tensile strength and hardness decrease especially at the mass fraction of Mn from 5% to 7%. The orientation relationship between martensite and austenite varies. The morphology and type of martensite change from lath α martensite whose substructure is mainly dislocations to bunchy laminar α martensite and laminar ε martensite whose substructure is mainly dislocations,twins through phase transition and stacking faults.
Abstract: Decarburization of non-oriented electrical steel in the two-phase region is a known method to acquire a columnar ferrite structure which may effectively ameliorate the microstructure homogeneity of materials. In this paper,the growth process of columnar grains was analyzed from the kinetics point of view. The results show that the columnar structure formation involves two stages:nucleation and directed growth. Directed growth is a sort of interface migration process caused by both reaction-diffusion and recrystallization growth,and fits a parabolic law. The growth rate and the annealing temperature do not show a monotonic functional relationship,but the growth rate reaches a maximal value when the temperature is 900℃. At last,we get the size constraint condition of columnar nuclei on the basis of the derived growth rate formula,which may present some significance for guiding the design of relevant decarburization parameters in industrial production.
Abstract: Large strain isothermal compression tests were carried out on a Gleeble-3800 thermal simulator to study the high temperature deformation behavior of Cr-Co-Mo-Ni gear steel. The constitutive equation and hot processing map of the steel were established based on experiment data. The results show that the flow stress decreases with increasing temperature,but increases with increasing strain rate. The flow stress can be described by the constitutive equation in a hyperbolic sine function and the averaged value of activation energy is 487.21 kJ·mol-1. The proper hot working regions shown by the hot processing map are the temperature of 1000-1100℃ and the strain rate of 0.1-1 s-1. In addition,the forging processes were simulated by finite element method based on the experiment,the effects of initial forging temperature and passes on the temperature and strain rate of forgings were analyzed,and the proper forging process parameters were obtained which are the initial forging temperature of 1000-1100℃ and the forging passes of 15.
Abstract: Differences between the ground and mechanically polished 316 LN stainless steel were characterized on the surface topography,surface residual strain and electron work function. The electrochemical behavior of the stainless steel was investigated in a borate buffer solution. The ground 316 LN stainless steel is featured by a rougher surface with scratches along the grinding direction.Compared with the mechanically polished sample,a thicker cold-worked layer(~50 μm) is imparted by surface grinding,indicating that the residual strain on the ground surface is much higher. The ground surface is more electrochemically active and exhibits a larger corrosion rate in the borate buffer solution,because of its rougher surface topography and a higher residual strain. The passive film on the mechanically polished sample is more compact and protective,due to the decrease of acceptor and donor density and the increase of total impedance of the passive film.
Abstract: A detection platform of coating failure processes was designed and constructed on the basis of laser electronic speckle pattern interferometry(ESPI). In situ,real-time and dynamic speckle interference fringes were observed and optimized without destroying the coating. An image of coating failure information was acquired by subtracting the zero moment stripe from the in situ and realtime stripes observed and binarizing the results. An experiment of the epoxy color paint/carbon steel system demonstrated the validity of ESPI. According to the ESPI image change,the immersion process of the epoxy color paint coating was divided into three stages:no spots in the initial stage,several blurry spots in the second stage and many clear spots in the last stage. As a result,we successfully realize the in situ,real-time and dynamic nondestructive testing of the coating interface failure and the microcosmic progress of underfilm metal corrosion.
Abstract: Aluminum-copper green bodies were successfully prepared by a non-aqueous gelcasting system. Scanning electron microscopy observations showed that the powder particles were completely wrapped by the polymer before degreasing,and the polymer in the metal body was completely removed after degreasing. A three-dimensional network polymer structure was obtained by the reaction mechanism. The degreasing process of the metal body was investigated by means of differential scanning calorimetry,thermogravimetry-derivative thermogravimetry and thermogravimetry-Fourier transform infrared spectroscopy. The kinetic equations and parameters were gotten according to Coats-Redfern method for non-isothermal weight loss curves. The results indicate that at different heating rates the reaction order is 1,the activation energy and pre-exponential factor are ranging from 79.86 to 108.63 kJ·mol-1 and 106 to 107 min-1,respectively. The activation energy reaction is sensitive to temperature and dynamics. The degreasing process is divided into two stages:a slight weight loss over a wide temperature range of 240-350℃ is due to the random chain scission and the main weight loss around 380 to 425℃ is attributed to depolymerization of monomers from the main chains and decrosslinking of the network polymer. The emissions of CO2,CO,NO2 and H2O are identifled during the degreasing process.
Abstract: The improvement in thermal deformation resistance of the copper stave in the bosh area and lower stack area of a blast furnace is the key factor for prolonging the blast furnace campaign life. The heat transfer performance and thermal deformation of the copper-steel composite stave at the bosh area and lower stack area were investigated by thermal testing and numerical simulation,and compared with those of the copper stave. The results show that the maximum temperature on the rib hot surface of the copper-steel composite stave without skull is 180℃ when the gas temperature is 1200℃,and approaches to the heat transfer performance of the copper stave. The maximum equivalent stress of the copper/steel interface is about 114.45 MPa,lower than the tensile strength of the copper-steel plate. The copper-steel composite stave subjects to bending deformation,and the center displacement in the z direction is 0.66 mm,about 25.8% lower than that of the copper stave. The up/down displacement in the z direction is 0.13 mm,about 50%lower than that of the copper stave. The curvature is 0.93×10-4 mm-1,about 51.81% lower than that of the copper stave. The thermal deformation resistance of the copper-steel composite stave is superior to that of the copper stave,and it can overcome the fracture of bolts and pipes in the copper stave due to excessive thermal deformation.
Abstract: The surface roughness rolling-transfer and change law of high strength steel strips and the surface roughness change law of working rolls are studied through a batch of field experiments and analyzed by a statistical method to find out a control method of producing high strength steel strips with especially required roughness. Experimental results show that the surface morphology of high strength steel strips is determined by the end of the continuous rolling mill. A surface roughness prediction model and a rolling-transfer rate model of high strength steel strips and a surface roughness prediction model of working rolls are established in this paper. The rolling-transfer behaviors of high strength steel strips are compared with those of normal strength steel strips. These models can be used to predict the surface roughness of high strength steel strips during industrial production,help to order the cold rolling sequence and make a rolling plan more efficiently,and determine the roll replacing time.
Abstract: Aiming at the active residual stress control of H-beams during a roller straightening process,an analysis model of stress evolution during the straightening process is constructed based on the elastic-plastic theory. A numerical solution method to quickly deal with the analysis model is investigated by discrete analysis. Then,an active design method of process parameters that can realize active residual stress control is established according to the analysis model. By using this method,process parameters are designed for typical specification H-beam straightening. Calculated results using the analysis model match those by a finite element method well and the analysis model makes the computational cost saved. The analysis model can achieve the result analysis of residual stress evolution within the feasible region in limited time. The process design method can get the process parameters of active control under specific target parameters and constraint conditions.
Abstract: The structure characteristic of a pressure relief valve embedded within a hydraulic circuit was analyzed. A nondimensional mathematical model was constructed by considering fluid compressibility,tube elasticity and energy loss when the valve poppet impacts its seat. Lyapunov exponent analyses were carried out. The aim is to capture the instability mechanism and chatter behavior of the relief valve. The non-smooth dynamical system theory and software MATLAB were used to draw one-parameter and two-parameter bifurcation diagrams. Grazing bifurcation which occurs at the poppet departure from the seat was explained. The results show that the flow rate into the valve and the setting pressure directly determine oscillation characters,and Hopf bifurcation,grazing bifurcation,periodic and chaotic phenomena appear. The measured bifurcation diagram at the spring pre-compression value x0=5 mm was presented.The mathematical model of the relief valve was verified on a test platform.
Abstract: Consensus problems were investigated for discrete-time heterogeneous multi-agent systems composed of first-order agents and second-order agents. Distributed consensus protocols with and without the bound communication delay were respectively designed. By transforming the systems into autonomous discrete-time linear time-invariant systems and using the matrix theory and algebraic graph theory,sufficient conditions are derived for the systems reaching consensus. The obtained sufficient conditions are related to the sampling period,the control parameter and the system topology structure. It is proved that the consensus of the systems is independent of the bound communication delay. Simulation results verify the correctness of the theoretical results.
Abstract: Due to structural redundancy,strong energy absorption and energy dissipation capacity of nail joints,wood buildings behave good seismic performance in earthquakes. Cross laminated timber is a new generation of engineered wood-based product. Based on tests of three kinds of cross laminated timber connections,Pinching4 model in Open Sees as a user-defined element is applied to simulate the hysteresis response of the connections,which is highly nonlinear,strength degradation,stiffness degradation,and pinching. The primary and follower half-cycle energy damage model is used for damage quantitative analysis of the connections,and the damage factor ranges corresponding to five damage levels of cross laminated timber connections are given in this article. The study shows that good simulation results are obtained and it is also illustrated that Pinching4 model is valid and feasible to predict the hysteretic response of wood connections. Different damage factors responding to varied damage degrees are consistent with the experimental rules. The dispersion degrees of the damage factors are relatively low with the mean values in the reasonable ranges.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
