The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSN...The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSNS-II)commenced in 2024.The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities,namely double-spoke and six-cell elliptical cavities,after the drift tube linac(DTL).The development of the double-spoke superconducting cavity began in early 2021,and by January 2023,the welding,post-processing,and vertical tests of two 324 MHz double-spoke cavity prototypes were completed,with vertical test gradients of 11.6 and 15 MV/m,and Q_(0)≥3×10^(10)@E_(acc)≤10 MV/m.The R&D of the cryomodule began in January 2022.In October 2023,the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced,with the installation of the cryomodule and valve box completing in two months.In January 2024,a horizontal test of the cryomodule was completed,making it the first double-spoke cavity cryomodule in China.The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m,respectively.This article provides a detailed introduction to the double-spoke superconducting cavity,tuner,coupler,and cryomodule,elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule,and provides a detailed analysis of the horizontal test results.展开更多
Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend ...Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend of tidal current turbine （TCT） for its economies. Instead of the similarity to the wind turbine, the tidal turbine has the characteristics of high hydrodynamic efficiency, big thrust, reliable sealing system, tight power transmission structure, etc. In this paper, a l/5th scale horizontal axis tidal current turbine has been designed, manufactured and tested before the full scale device design. Firstly, the three-blade horizontal axis rotor was designed based on traditional blade element momentum theory and its hydrodynamic performance was predicted in numerical model. Then the power train system and stand-alone electrical control unit of tidal current turbine, whose performances were accessed through the bench test carried out in workshop, were designed and presented. Finally, offshore tests were carried out and the power performance of the rotor was obtained and compared with the published literatures, and the results showed that the power coefficient was satisfactory, which agrees with the theoretical predictions.展开更多
Frame-masonry horizontal hybrid structure is a new type of self-built residence in the rural areas of Fujian Province in recent years. A shaking table test for 1/2 scale model is carried out on the basis of one repres...Frame-masonry horizontal hybrid structure is a new type of self-built residence in the rural areas of Fujian Province in recent years. A shaking table test for 1/2 scale model is carried out on the basis of one representative rural structure, and the dynamic characteristics and seismic responses of this experimental model are measured. As a supplement, the finite element model of the prototype structure is built by ANSYS software,and simulation and test results are contrasted and analyzed. The results show that according to this structure,the beam-column joint of the frame part has stress concentration and the destruction pattern of the masonry part is similar to brick-masonry structure. There are obvious differences in lateral stiffness of each floor and direction,and the mass center does not coincide with the stiffness center, which can lead to excessive torsion and story drift of this structure under earthquakes of a certain intensity. Because of poor construction quality, unfavorable structural measures and irrational structural system in present rural areas, there is a potential safety threat with this type of structures in highly seismic region. Some suggestions for strengthening and retrofitting frame-masonry horizontal hybrid structures are pointed out.展开更多
The fundamental shear horizontal（SH0） wave has several unique features that are attractive for long-range nondestructive testing（NDT）. By a careful design of the geometric configuration, electromagnetic acoustic t...The fundamental shear horizontal（SH0） wave has several unique features that are attractive for long-range nondestructive testing（NDT）. By a careful design of the geometric configuration, electromagnetic acoustic transducers（EMATs） have the capability to generate a wide range of guided wave modes, such as Lamb waves and shear-horizontal（SH） waves in plates. However, the performance of EMATs is influenced by their parameters. To evaluate the performance of periodic permanent magnet（PPM） EMATs, a distributed-line-source model is developed to calculate the angular acoustic field cross-section in the far-field. Numerical analysis is conducted to investigate the performance of such EMATs with different geometric parameters, such as period and number of magnet arrays, and inner and outer coil widths. Such parameters have a great influence on the directivity of the generated SH0 waves that arises mainly in the amplitude and width of both main and side lobes. According to the numerical analysis, these parameters are optimized to obtain better directivity. Optimized PPM EMATs are designed and used for NDT of strip plates. Experimental results show that the lateral boundary of the strip plate has no perceivable influence on SHO-wave propagation, thus validating their used in NDT. The proposed model predicts the radiation pattern ofPPM EMATs, and can be used for their parameter optimization.展开更多
As an important part of offshore wind turbine support and fixed units, the multibucket jacket foundation bears large loads and a complex marine environment. In this paper, the horizontal bearing characteristics of the...As an important part of offshore wind turbine support and fixed units, the multibucket jacket foundation bears large loads and a complex marine environment. In this paper, the horizontal bearing characteristics of the four-bucket jacket foundation of offshore wind power in sandy soil are studied. Through model tests and numerical simulations, the influence of bucket foundation sealing properties, load application speed, and loading direction on foundation-bearing capacity are discussed. The results show that the horizontal ultimate bearing capacity of the foundation in the nonsealing condition is decreased by 51.3% compared with the sealing condition;therefore, after the foundation penetration construction is completed, the bucket sealing must be ensured to increase the load-bearing performance of the structure. At a loading speed of 3.25 mm/s, the horizontal ultimate bearing capacity of the foundation is increased by 9.4% over the working condition of 1.85 mm/s. The bearing capacity of the foundation is maximized in the loading direction α =45° and is the smallest when α =0°. That is, the foundation can maximize its loadbearing performance under the condition of single-bucket compression/tension. During the design process, the main load of the structure should be loaded in the 45° direction. The contrast error of the experiment and numerical simulation does not exceed 10%. The research results have important guiding importance for designing and constructing the jacket foundation and can be used as a reference for the stable operation and sustainable development of offshore wind power systems.展开更多
A flexible sidetracking stimulation technology of horizontal wells is formed to develop the lateral deep remaining oil and gas resources of the low-permeability mature oilfields.This technology first uses the flexible...A flexible sidetracking stimulation technology of horizontal wells is formed to develop the lateral deep remaining oil and gas resources of the low-permeability mature oilfields.This technology first uses the flexible sidetracking tool to achieve low-cost sidetracking in the old wellbore,and then uses the hydraulic jet technology to induce multiple fractures to fracture.Finally,the bullhead fracturing of multi-cluster temporary plugging for the sidetracking hole is carried out by running the tubing string,to realize the efficient development of the remaining reserves among the wells.The flexible sidetracking stimulation technology involves flexible sidetracking horizontal wells drilling and sidetracking horizontal well fracturing.The flexible sidetracking horizontal well drilling includes three aspects:flexible drill pipe structure and material optimization,drilling technology,and sealed coring tool.The sidetracking horizontal well fracturing includes two aspects:fracturing scheme optimization,fracturing tools and implementation process optimization.The technology has been conducted several rounds of field tests in the Ansai Oilfield of Changqing,China.The results show that by changing well type and reducing row spacing of oil and water wells,the pressure displacement system can be well established to achieve effective pressure transmission and to achieve the purpose of increasing liquid production in low-yield and low-efficiency wells.It is verified that the flexible sidetracking stimulation technology can provide favorable support for accurately developing remaining reserves in low-permeability reservoirs.展开更多
The operational experience of a horizontal segment well within the hard brittle shale layer of Longmaxi Formation in the southern Sichuan area demonstrates that the high-density oil-based drillingfluid(HDOF)induced do...The operational experience of a horizontal segment well within the hard brittle shale layer of Longmaxi Formation in the southern Sichuan area demonstrates that the high-density oil-based drillingfluid(HDOF)induced down-hole working conditions(high-temperature,high-pressure,and solid-phase-dominance)directly impact the stability of the wellbore wall.Focusing on the impact of bottom-hole osmotic pressure and solid phase content and a series of density-reductionfield tests,we identified suitable countermeasures.In this paper,we discuss the impact of high osmotic pressure and operational measures,and provide details of thefield tests,which indicate that maintaining a higher osmotic pressure at the bottom-hole can reduce the formation pore pressure of the bottom-hole,widen thefluid density window,and maintain the stability of the wellbore wall.By improving the HDOF formula,such as using new treatment agents(e.g.,polymer-modified nano-sealing agent and ultra-micro barite weight additive)and optimizing the solid particle size distribution of HDOF,we can effectively address the down-hole problems.Thefield test of“pressure-controlled drillingþdensity reduction”in horizontal drilling operations was found to reduce the complexity of down-hole faults,improve the rate of penetration,and reduce overall costs.展开更多
The influence of different types of roots on the soil is complex and still remains unclear.Four in-situ extrusion tests were conducted on two types of root systems,namely fibrous and tap root system,for three plants,E...The influence of different types of roots on the soil is complex and still remains unclear.Four in-situ extrusion tests were conducted on two types of root systems,namely fibrous and tap root system,for three plants,Eleusine indica,Potentilla anserine,and Artemisia argyi,according to the classification in Botany,and the thrust-displacement curves and failure patterns of different samples were analysed by comparison to fill the aforementioned gap.Results reveal that the roots can reduce the characteristics of soil brittleness and enhance its capability to resist large deformation,and different root types contribute different effects to the strain-hardening behavior of the root-soil mass.The contribution of the fibrous root system to strength is limited,whilst the tap root system substantially enhances strength and stiffness.Results of failure patterns show that fibrous and tap root systems affect soil solidification and surface cracking reduction.However,the effect of the tap root system depends on the composition of lateral and tap roots:long and rich lateral roots are effective for resisting the creation of cracks,but thick tap roots with few and thin lateral roots may lead to several surface cracks.展开更多
The state of deep mine rigid shaft fUrniture horizontal force calculation in China is introduced and the calculating model of horizontal force is determined. Based on the interaction between hoisting vessel and shaft ...The state of deep mine rigid shaft fUrniture horizontal force calculation in China is introduced and the calculating model of horizontal force is determined. Based on the interaction between hoisting vessel and shaft furniture, the vertical mobel test device is built and a large number of model tests and analyses are carried out. At last, the relationship between horizontal force and hoisting end load, hoisting speed or bunton level interval is gained. The three parameters horizontal force calculating equation of beep mine rigid shaft furniture is given and it can guide the design and calculation of shaft engineering.展开更多
Subjective visual vertical(SVV)and subjective visual horizontal(SVH)tests can be used to evaluate the perception of verticality and horizontality,respectively,and can aid the diagnosis of otolith dysfunction in clinic...Subjective visual vertical(SVV)and subjective visual horizontal(SVH)tests can be used to evaluate the perception of verticality and horizontality,respectively,and can aid the diagnosis of otolith dysfunction in clinical practice.In this study,SVV and SVH screen version tests are implemented using virtual reality(VR)equipment;the proposed test method promotes a more immersive feeling for the subject while using a simple equipment configuration and possessing excellent mobility.To verify the performance of the proposed VR-based SVV and SVH tests,a reliable comparison was made between the traditional screen-based SVV and SVH tests and the proposed method,based on 30 healthy subjects.The average results of our experimental tests on the VR-based binocular SVV and SVH equipment were−0.15◦±1.74 and 0.60◦±1.18,respectively.The proposed VR-based method satisfies the normal tolerance for horizontal or vertical lines,i.e.,a±3◦error,as defined in previous studies,and it can be used to replace existing test methods.展开更多
Multi-stage volume fracturing of horizontal wells is the main means to develop tight gas reservoirs.Complex fracture networks of various shapes are generated around the wellbore after volume fracturing.At present,howe...Multi-stage volume fracturing of horizontal wells is the main means to develop tight gas reservoirs.Complex fracture networks of various shapes are generated around the wellbore after volume fracturing.At present,however,most of the well test models suitable for fracturing horizontal wells take all hydraulic fractures as single main fractures,which results in a large error between well test interpretation result and actual situation.As a result,the fracture network characteristic parameters of the stimulated areas cannot be obtained accurately.To this end,a well test model for complex fracture networks in tight-gas fracturing horizontal wells was established on the basis of the non-structural discrete fracture model.Then,this model was solved by using thefinite element method with combined triangular elements and linear elements.And accordingly,the well test type curves of a horizontal well under different fracture network patterns(rectangular,elliptical and hyperbolic)were prepared.Based on this,well test type curves were analyzed from the aspects of characteristics and influential factors and were compared with those obtained from the conventional single-fracture model.Finally,the new model was applied in well test interpretation of one multi-stage volume fracturing horizontal well in the gas reservoir of Permian Shan 1 formation in the Qingyang Gas Field of the Ordos Basin.And the following research results were obtained.First,the biggest difference of well test type curve between the fracture network model and the conventional single-fracture model occurs in the early stage,the characteristics offirst linearflow regime are replaced with the characteristics of pseudo-radialflow regime in the stimulated area.Second,the end time of the pseudo-radialflow regime in the stimulated area is mainly dominated by the size and shape of the stimulated area.The larger the stimulated area is,the longer the pseudo-radialflow regime lasts.As the shape of the stimulated area approaches to be elongated,the characteristics of the well test type curve obtained by the new model are more consistent with those by the single-fracture model.Third,the pressure derivative value of the pseudo-radialflow regime in the stimulated area is mainly dependent on the conductivity and density of the fracture network.The higher the density or the conductivity of fracture network in the stimulated area is,the earlier the wellbore storage effect regime ends,the lower the pressure derivative value of the pseudo-radialflow regime in the stimulated area is and the more obvious the characteristics of the horizontal line are.In conclusion,case study results confirm that the new model is reliable and practical and can provide accurate reservoir parameters as well as the size of the effectively stimulated area by volume fracturing and the conductivity of fracture network,which is conducive to evaluating the stimulation effect of volume fracturing and predicting the postfrac production performance.展开更多
Microseismic data shows that some unconventional reservoirs comprise well-developed natural fractures and complex hydraulic fracture networks.It is neither practical nor advantageous to simulate a huge number of natur...Microseismic data shows that some unconventional reservoirs comprise well-developed natural fractures and complex hydraulic fracture networks.It is neither practical nor advantageous to simulate a huge number of natural and hydraulic fractures with numerical models.Given that the conventional dual-porosity models are not applicable to the highly discrete natural fractures,the paper develops a semianalytical well testing model for horizontal wells with hydraulic fracture networks and randomly-distributed discretely natural fractures.The proposed model has the capability to analyze the pressure behaviors by considering complex fracture networks and isolated natural fractures rapidly and efficiently.The model includes diffusivity equations in three domains:(1)matrix,(2)discretely natural fractures,and(3)hydraulic fracture networks.The pressure transient solution of these diffusivity equations is obtained by using Laplace transforms and super-position principle.We verify the presented model by performing a case study with a numerical simulator for complex natural fractures.It is found that there are some interestingflow behaviors for fracture-network horizontal well with discretely natural fractures like bilinearflow,“V-shape”caused byfluid supply,pseudo boundary-dominatedflow,impact of natural fractures,etc.The pseudo boundary-dominatedflow provides us the information about how large the area covered by hydraulic fracture networks.The impact of natural fracture shows the pa-rameters of natural fractures.This work provides a good understanding of transient pressure behaviors in unconventional reservoirs and guidelines for the producer optimizefield development and well economics.展开更多
With the rapid development of shale gas exploration and development in China,casing deformation in shale gas horizontal wells happens frequently,which directly impacts the development efficiency and benefits of shale ...With the rapid development of shale gas exploration and development in China,casing deformation in shale gas horizontal wells happens frequently,which directly impacts the development efficiency and benefits of shale gas.In order to explore casing deformation prediction,prevention and treatment methods,this paper analyzes the geological and engineering causes of casing deformation in shale-gas horizontal wells through laboratory work,such as the casing resistance to internal pressure alternating test,the ground simulation test and systematical casing deformation characteristic analysis of MIT24 caliper logging,and the large-scale physical simulation test and numerical simulation of casing deformation.Then,combined with the generalized shear activity criterion,a new method for evaluating casing deformation risk points and some technical measures for preventing casing deformation were formulated.And the following research results were obtained.First,the deformation characteristics of 119 casing deformation points in 23 wells interpreted by MIT24 caliper logging are consistent with the mechanical behaviors of shear compression deformation test.Second,the large-scale physical simulation test shows that natural fault-fractures slip obviously under the state of strike-slip stress.Third,numerical simulation shows that the compression stress on casing increases with the increase of fault-fracture slip.When the fault-fracture slip is between 7.5 mm and 9.0 mm,the casing reaches the critical yield strength and begins to undergo plastic deformation.The“temporary fracture plugging+long segment and multi-cluster”and other technologies are field tested in 28 wells in Weiyuan area of southern Sichuan Basin.The casing deformation rate decreases from 54%(before this research)to 14.3%,and the segment loss rate decreases from 7.8%to 0,which reveals remarkable achievements in casing deformation treatment.In conclusion,the shear slip of fault and macro fractures(referred to as fault-fracture)is the main cause of casing deformation in shale gas horizontal wells,and some measures(e.g.“temporary fracture plugging+long segment and multi-cluster”,reducing fracturing scale and releasing wellbore pressure properly)shall be taken in advance to reduce the fault-fracture activity before the risk point of casing deformation is fractured,so as to reach the goal of casing deformation prevention.展开更多
Horizontal shale gas well fracturing is mostly carried out by pumping bridge plugs.In the case of casing deformation,the bridge plug can not be pumped down to the designated position,so the hole sections below the def...Horizontal shale gas well fracturing is mostly carried out by pumping bridge plugs.In the case of casing deformation,the bridge plug can not be pumped down to the designated position,so the hole sections below the deformation could not be stimulated according to the design program.About 30%of horizontal shale gas wells in the Changning and Weiyuan Blocks,Sichuan Basin,suffer various casing deformation after fracturing.Previously,the hole sections which could not be stimulated due to casing deformation were generally abandoned.As a result,the resources controlled by shale gas wells weren't exploited effectively and the fracturing effect was impacted greatly.There are a lot of difficulties in investigating casing deformation,such as complex mechanisms,various influencing factors and unpredictable deformation time.Therefore,it is especially important to seek a staged fracturing technology suitable for the casing deformation sections.In this paper,the staged fracturing technology with sand plugs inside fractures and the staged fracturing technology with temporary plugging balls were tested in casing deformation wells.The staged fracturing technology with sand plugs inside fractures was carried out in the mode of single-stage perforation and single-stage fracturing.The staged fracturing technology with temporary plugging balls was conducted in the mode of single perforation,continuous fracturing and staged ball dropping.Then,two kinds of technologies were compared in terms of their advantages and disadvantages.Finally,they were tested on site.According to the pressure response,the pressure monitoring of the adjacent wells and the microseismic monitoring in the process of actual fracturing,both technologies are effective in the stimulation of the casing deformation sections,realizing well control reserves efficiently and guaranteeing fracturing effects.展开更多
In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters （i.e. austenitizing temperature and time, and austempering temperature and ...In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters （i.e. austenitizing temperature and time, and austempering temperature and time） on microstructure and mechanical properties of LZQT500-7 ductile iron dense bars with 172 mm in diameter which were produced by horizontal continuous casting （HCC）. The results show that the major factors influencing the hardness of austempered ductile iron （ADI） are austenitizing temperature and austempering temperature. The fraction of retained austenite increases as the austenitizing and austempering temperatures increase. When austenitizing temperature is low, acicular ferrite and retained austenite can be efifciently obtained by appropriately extending the austenitizing time. The proper austmepering time could ensure enough stability of retained austenite and prevent high carbon austenite decomposition. The optimal mechanical properties of ADI can be achieved with the fol owing process parameters： austenitizing temperature and time are 866 ＆#176;C and 135 min, and austempering temperature and time are 279 ＆#176;C and 135 min, respectively. The microstructure of ADI under the optimal austempering process consists of ifne acicular ferrite and a smal amount of retained austenite, and the hardness, tensile strength, yield strength, elongation and impact toughness of the bars are HBW 476, 1670 MPa, 1428 MPa, 2.93%and 25.7 J, respectively.展开更多
Rock slope with horizontal-layered fractured structure(HLFS)has high stability in its natural state.However,a strong earthquake can induce rock fissure expansion,ultimately leading to slope failure.In this study,the d...Rock slope with horizontal-layered fractured structure(HLFS)has high stability in its natural state.However,a strong earthquake can induce rock fissure expansion,ultimately leading to slope failure.In this study,the dynamic response,failure mode,and spectral characteristics of rock slope with HLFS under strong earthquake conditions were investigated based on the large-scale shaking table model test.On this basis,multiple sets of numerical calculation models were further established by UDEC discrete element program.Five influencing factors were considered in the parametric study of numerical simulations,including slope height,slope angle,bedding-plane spacing and secondary joint spacing as well as bedrock dip angle.The results showed that the failure process of rock slope with HLFS under earthquake action is mainly divided into four phases,i.e.,the tensile crack of the slope shoulder joints and shear dislocation at the top bedding plane,the extension of vertical joint cracks and increase of shear displacement,the formation of step-through sliding surfaces and the instability,and finally collapse of fractured rock mass.The acceleration response of slopes exhibits elevation amplification effect and surface effect.Numerical simulations indicate that the seismic stability of slopes with HLFS exhibits a negative correlation with slope height and angle,but a positive correlation with bedding-plane spacing,joint spacing,and bedrock dip angle.The results of this study can provide a reference for seismic stability evaluation of weathered rock slopes.展开更多
This research investigates water-wave scattering via a horizontal perforated plate fixed at the still water level through analytical studies and physical model tests.The velocity potential decomposition method is comb...This research investigates water-wave scattering via a horizontal perforated plate fixed at the still water level through analytical studies and physical model tests.The velocity potential decomposition method is combined with an efficient iterative algorithm to develop an analytical solution in which the quadratic pressure drop condition is imposed on the horizontal perforated plate.The analytical results are in good agreement with the results of an independently developed iterative boundary element method(BEM)solution.Experimental tests are carried out in a wave flume to measure the reflection coefficient and transmission coefficient of the horizontal perforated plate,and the analytical results agree reasonably well with the experimental data.The influence of various structural parameters of the horizontal perforated plate on the hydrodynamic parameters of reflection coefficient,transmission coefficient,energy-loss coefficient,and wave force are analyzed on the basis of the analytical solution.Useful results for the practical engineering application of horizontal perforated plates are also presented.展开更多
In this paper, solutions to the 3D transient flow mathematical model for horizontal wells in box-rounded reservoirs are presented. The solutions are derived in Laplace transform domain by employing integral transform ...In this paper, solutions to the 3D transient flow mathematical model for horizontal wells in box-rounded reservoirs are presented. The solutions are derived in Laplace transform domain by employing integral transform and point-source superposition. Both efficient computation of pressure responses and practical technology of oil field application mentioned here may be used to interpret the data from unsteady-state horizontal well testing.展开更多
In order to accurately evaluate the fracturing stimulation effect of horizontal wells in shale gas reservoirs,it is suggested to establish a model to predict the temperature distribution in the wellbore of horizontal ...In order to accurately evaluate the fracturing stimulation effect of horizontal wells in shale gas reservoirs,it is suggested to establish a model to predict the temperature distribution in the wellbore of horizontal well and an inversion model of DTS data by using MCMC algorithm,and optimize the production profile interpretation process.In this paper,the characteristics of temperature profile of fractured horizontal wells in shale gas reservoirs were analyzed and the main factors affecting the temperature profile were figured out.Finally,the newly established inversion model was applied to the production profile interpretation of one case well in a certain shale gas reservoir.And the following research results were obtained.First,the temperature profile of fractured horizontal wells is in the shape of irregular“saw tooth”,and each“saw tooth”corresponds to an effective hydraulic fracture with fluid inflow.Second,the longer the fracture is,the greater the wellbore temperature drop at the corresponding fracture location is,and the gas flow rate in the fracture is positively correlated with the temperature drop.Third,from the perspective of influence degree,the factors influencing the temperature profile of fractured horizontal wells in shale gas reservoirs are ranked from the strong to the weak as follows:fracture half-length,gas flow rate,permeability of stimulated area,wellbore diameter,fracture conductivity,horizontal inclination angle,and comprehensive thermal conductivity,among which,the first three are main controlling factors.Fourth,the MCMC inversion method is applied to invert the DST temperature data of the case well.The temperature profile predicted in the model is better accordant with the measured DTS profile,and the absolute error of the predicted temperature at different levels of effective hydraulic fractures is less than 0.02°C.The interpreted gas flow rate of each fracturing stage is closer to the field measurement,and the deviation of the maximum gas flow rate of a single fracturing stage is only 180.35 m^(3)/d.The absolute error between single-well gas production rate and gas production rate measured at the wellhead is less than 3 m^(3)/d,which proves the reliability of this newly developed inversion model.展开更多
This study proposes a novel open-type rectangular breakwater combined with horizontal perforated plates on both sides to enhance the sheltering effect of the rectangular box-type breakwaters against longer waves.The h...This study proposes a novel open-type rectangular breakwater combined with horizontal perforated plates on both sides to enhance the sheltering effect of the rectangular box-type breakwaters against longer waves.The hydrodynamic characteristics of this breakwater are analyzed through analytical potential solutions and experimental tests.The quadratic pressure drop conditions are exerted on the horizontal perforated plates to facilitate assessing the effect of wave height on the dissipated wave energy of breakwater through the analytical solution.The hydrodynamic quantities of the breakwater,including the reflection,transmission,and energyloss coefficients,together with vertical and horizontal wave forces,are calculated using the velocity potential decomposition method as well as an iterative algorithm.Furthermore,the reflection and transmission coefficients of the breakwater are measured by conducting experimental tests at various wave periods,wave heights,and both porosities and widths of the horizontal perforated plates.The analytical predicted results demonstrate good agreement with the iterative boundary element method solution and measured data.The influences of variable incident waves and structure parameters on the hydrodynamic characteristics of the breakwater are investigated through further calculations based on analytical solutions.Results indicate that horizontal perforated plates placed on the water surface for both sides of the rectangular breakwater can enhance the wave dissipation ability of the breakwater while effectively decreasing the transmission and reflection coefficients.展开更多
文摘The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSNS-II)commenced in 2024.The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities,namely double-spoke and six-cell elliptical cavities,after the drift tube linac(DTL).The development of the double-spoke superconducting cavity began in early 2021,and by January 2023,the welding,post-processing,and vertical tests of two 324 MHz double-spoke cavity prototypes were completed,with vertical test gradients of 11.6 and 15 MV/m,and Q_(0)≥3×10^(10)@E_(acc)≤10 MV/m.The R&D of the cryomodule began in January 2022.In October 2023,the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced,with the installation of the cryomodule and valve box completing in two months.In January 2024,a horizontal test of the cryomodule was completed,making it the first double-spoke cavity cryomodule in China.The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m,respectively.This article provides a detailed introduction to the double-spoke superconducting cavity,tuner,coupler,and cryomodule,elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule,and provides a detailed analysis of the horizontal test results.
基金supported by the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51521064)the National High Technology Research and Development of China(863 Program,Grant No.2011AA050201)+2 种基金the Natural Science Foundation of Zhejiang Province(Grant No.LY14E050019)the Youth Funds of the State Key Laboratory of Fluid Power Transmission and Control SKLo FP_QN_1401the special funds of state oceanic renewable energy(Grant No.GHME2013ZB03)
文摘Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend of tidal current turbine （TCT） for its economies. Instead of the similarity to the wind turbine, the tidal turbine has the characteristics of high hydrodynamic efficiency, big thrust, reliable sealing system, tight power transmission structure, etc. In this paper, a l/5th scale horizontal axis tidal current turbine has been designed, manufactured and tested before the full scale device design. Firstly, the three-blade horizontal axis rotor was designed based on traditional blade element momentum theory and its hydrodynamic performance was predicted in numerical model. Then the power train system and stand-alone electrical control unit of tidal current turbine, whose performances were accessed through the bench test carried out in workshop, were designed and presented. Finally, offshore tests were carried out and the power performance of the rotor was obtained and compared with the published literatures, and the results showed that the power coefficient was satisfactory, which agrees with the theoretical predictions.
基金the National Natural Science Foundation of China(No.51578160)
文摘Frame-masonry horizontal hybrid structure is a new type of self-built residence in the rural areas of Fujian Province in recent years. A shaking table test for 1/2 scale model is carried out on the basis of one representative rural structure, and the dynamic characteristics and seismic responses of this experimental model are measured. As a supplement, the finite element model of the prototype structure is built by ANSYS software,and simulation and test results are contrasted and analyzed. The results show that according to this structure,the beam-column joint of the frame part has stress concentration and the destruction pattern of the masonry part is similar to brick-masonry structure. There are obvious differences in lateral stiffness of each floor and direction,and the mass center does not coincide with the stiffness center, which can lead to excessive torsion and story drift of this structure under earthquakes of a certain intensity. Because of poor construction quality, unfavorable structural measures and irrational structural system in present rural areas, there is a potential safety threat with this type of structures in highly seismic region. Some suggestions for strengthening and retrofitting frame-masonry horizontal hybrid structures are pointed out.
基金supported by National Natural Science Foundation of China(Grant Nos.51075012,10772008)Beijing Municipal Natural Science Foundation of China(Grant No.1122005)
文摘The fundamental shear horizontal（SH0） wave has several unique features that are attractive for long-range nondestructive testing（NDT）. By a careful design of the geometric configuration, electromagnetic acoustic transducers（EMATs） have the capability to generate a wide range of guided wave modes, such as Lamb waves and shear-horizontal（SH） waves in plates. However, the performance of EMATs is influenced by their parameters. To evaluate the performance of periodic permanent magnet（PPM） EMATs, a distributed-line-source model is developed to calculate the angular acoustic field cross-section in the far-field. Numerical analysis is conducted to investigate the performance of such EMATs with different geometric parameters, such as period and number of magnet arrays, and inner and outer coil widths. Such parameters have a great influence on the directivity of the generated SH0 waves that arises mainly in the amplitude and width of both main and side lobes. According to the numerical analysis, these parameters are optimized to obtain better directivity. Optimized PPM EMATs are designed and used for NDT of strip plates. Experimental results show that the lateral boundary of the strip plate has no perceivable influence on SHO-wave propagation, thus validating their used in NDT. The proposed model predicts the radiation pattern ofPPM EMATs, and can be used for their parameter optimization.
文摘As an important part of offshore wind turbine support and fixed units, the multibucket jacket foundation bears large loads and a complex marine environment. In this paper, the horizontal bearing characteristics of the four-bucket jacket foundation of offshore wind power in sandy soil are studied. Through model tests and numerical simulations, the influence of bucket foundation sealing properties, load application speed, and loading direction on foundation-bearing capacity are discussed. The results show that the horizontal ultimate bearing capacity of the foundation in the nonsealing condition is decreased by 51.3% compared with the sealing condition;therefore, after the foundation penetration construction is completed, the bucket sealing must be ensured to increase the load-bearing performance of the structure. At a loading speed of 3.25 mm/s, the horizontal ultimate bearing capacity of the foundation is increased by 9.4% over the working condition of 1.85 mm/s. The bearing capacity of the foundation is maximized in the loading direction α =45° and is the smallest when α =0°. That is, the foundation can maximize its loadbearing performance under the condition of single-bucket compression/tension. During the design process, the main load of the structure should be loaded in the 45° direction. The contrast error of the experiment and numerical simulation does not exceed 10%. The research results have important guiding importance for designing and constructing the jacket foundation and can be used as a reference for the stable operation and sustainable development of offshore wind power systems.
基金Supported by the National Key Research and Development Program of China(2023YFF0615403)CNPC Science and Technology Project(2023ZZ0803).
文摘A flexible sidetracking stimulation technology of horizontal wells is formed to develop the lateral deep remaining oil and gas resources of the low-permeability mature oilfields.This technology first uses the flexible sidetracking tool to achieve low-cost sidetracking in the old wellbore,and then uses the hydraulic jet technology to induce multiple fractures to fracture.Finally,the bullhead fracturing of multi-cluster temporary plugging for the sidetracking hole is carried out by running the tubing string,to realize the efficient development of the remaining reserves among the wells.The flexible sidetracking stimulation technology involves flexible sidetracking horizontal wells drilling and sidetracking horizontal well fracturing.The flexible sidetracking horizontal well drilling includes three aspects:flexible drill pipe structure and material optimization,drilling technology,and sealed coring tool.The sidetracking horizontal well fracturing includes two aspects:fracturing scheme optimization,fracturing tools and implementation process optimization.The technology has been conducted several rounds of field tests in the Ansai Oilfield of Changqing,China.The results show that by changing well type and reducing row spacing of oil and water wells,the pressure displacement system can be well established to achieve effective pressure transmission and to achieve the purpose of increasing liquid production in low-yield and low-efficiency wells.It is verified that the flexible sidetracking stimulation technology can provide favorable support for accurately developing remaining reserves in low-permeability reservoirs.
基金supported by the National Science and Technology Program during the Thirteenth Five-year Plan Period(CN).
文摘The operational experience of a horizontal segment well within the hard brittle shale layer of Longmaxi Formation in the southern Sichuan area demonstrates that the high-density oil-based drillingfluid(HDOF)induced down-hole working conditions(high-temperature,high-pressure,and solid-phase-dominance)directly impact the stability of the wellbore wall.Focusing on the impact of bottom-hole osmotic pressure and solid phase content and a series of density-reductionfield tests,we identified suitable countermeasures.In this paper,we discuss the impact of high osmotic pressure and operational measures,and provide details of thefield tests,which indicate that maintaining a higher osmotic pressure at the bottom-hole can reduce the formation pore pressure of the bottom-hole,widen thefluid density window,and maintain the stability of the wellbore wall.By improving the HDOF formula,such as using new treatment agents(e.g.,polymer-modified nano-sealing agent and ultra-micro barite weight additive)and optimizing the solid particle size distribution of HDOF,we can effectively address the down-hole problems.Thefield test of“pressure-controlled drillingþdensity reduction”in horizontal drilling operations was found to reduce the complexity of down-hole faults,improve the rate of penetration,and reduce overall costs.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23090402)the National Natural Science Foundation of China(Nos.41790442,41825018)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0904)。
文摘The influence of different types of roots on the soil is complex and still remains unclear.Four in-situ extrusion tests were conducted on two types of root systems,namely fibrous and tap root system,for three plants,Eleusine indica,Potentilla anserine,and Artemisia argyi,according to the classification in Botany,and the thrust-displacement curves and failure patterns of different samples were analysed by comparison to fill the aforementioned gap.Results reveal that the roots can reduce the characteristics of soil brittleness and enhance its capability to resist large deformation,and different root types contribute different effects to the strain-hardening behavior of the root-soil mass.The contribution of the fibrous root system to strength is limited,whilst the tap root system substantially enhances strength and stiffness.Results of failure patterns show that fibrous and tap root systems affect soil solidification and surface cracking reduction.However,the effect of the tap root system depends on the composition of lateral and tap roots:long and rich lateral roots are effective for resisting the creation of cracks,but thick tap roots with few and thin lateral roots may lead to several surface cracks.
文摘The state of deep mine rigid shaft fUrniture horizontal force calculation in China is introduced and the calculating model of horizontal force is determined. Based on the interaction between hoisting vessel and shaft furniture, the vertical mobel test device is built and a large number of model tests and analyses are carried out. At last, the relationship between horizontal force and hoisting end load, hoisting speed or bunton level interval is gained. The three parameters horizontal force calculating equation of beep mine rigid shaft furniture is given and it can guide the design and calculation of shaft engineering.
基金supported by the Soonchunhyang University Research Fund and 2018 Ulsan University Hospital Research Grant(UUH-2018-12)(Grantee:JYP,http://www.uuh.ulsan.kr).The authors are grateful for their supports.
文摘Subjective visual vertical(SVV)and subjective visual horizontal(SVH)tests can be used to evaluate the perception of verticality and horizontality,respectively,and can aid the diagnosis of otolith dysfunction in clinical practice.In this study,SVV and SVH screen version tests are implemented using virtual reality(VR)equipment;the proposed test method promotes a more immersive feeling for the subject while using a simple equipment configuration and possessing excellent mobility.To verify the performance of the proposed VR-based SVV and SVH tests,a reliable comparison was made between the traditional screen-based SVV and SVH tests and the proposed method,based on 30 healthy subjects.The average results of our experimental tests on the VR-based binocular SVV and SVH equipment were−0.15◦±1.74 and 0.60◦±1.18,respectively.The proposed VR-based method satisfies the normal tolerance for horizontal or vertical lines,i.e.,a±3◦error,as defined in previous studies,and it can be used to replace existing test methods.
文摘Multi-stage volume fracturing of horizontal wells is the main means to develop tight gas reservoirs.Complex fracture networks of various shapes are generated around the wellbore after volume fracturing.At present,however,most of the well test models suitable for fracturing horizontal wells take all hydraulic fractures as single main fractures,which results in a large error between well test interpretation result and actual situation.As a result,the fracture network characteristic parameters of the stimulated areas cannot be obtained accurately.To this end,a well test model for complex fracture networks in tight-gas fracturing horizontal wells was established on the basis of the non-structural discrete fracture model.Then,this model was solved by using thefinite element method with combined triangular elements and linear elements.And accordingly,the well test type curves of a horizontal well under different fracture network patterns(rectangular,elliptical and hyperbolic)were prepared.Based on this,well test type curves were analyzed from the aspects of characteristics and influential factors and were compared with those obtained from the conventional single-fracture model.Finally,the new model was applied in well test interpretation of one multi-stage volume fracturing horizontal well in the gas reservoir of Permian Shan 1 formation in the Qingyang Gas Field of the Ordos Basin.And the following research results were obtained.First,the biggest difference of well test type curve between the fracture network model and the conventional single-fracture model occurs in the early stage,the characteristics offirst linearflow regime are replaced with the characteristics of pseudo-radialflow regime in the stimulated area.Second,the end time of the pseudo-radialflow regime in the stimulated area is mainly dominated by the size and shape of the stimulated area.The larger the stimulated area is,the longer the pseudo-radialflow regime lasts.As the shape of the stimulated area approaches to be elongated,the characteristics of the well test type curve obtained by the new model are more consistent with those by the single-fracture model.Third,the pressure derivative value of the pseudo-radialflow regime in the stimulated area is mainly dependent on the conductivity and density of the fracture network.The higher the density or the conductivity of fracture network in the stimulated area is,the earlier the wellbore storage effect regime ends,the lower the pressure derivative value of the pseudo-radialflow regime in the stimulated area is and the more obvious the characteristics of the horizontal line are.In conclusion,case study results confirm that the new model is reliable and practical and can provide accurate reservoir parameters as well as the size of the effectively stimulated area by volume fracturing and the conductivity of fracture network,which is conducive to evaluating the stimulation effect of volume fracturing and predicting the postfrac production performance.
基金supported by National Key S&T Special Projects(2016ZX05047-004 and 2016ZX05030)National Natural Science Foundation of China(U1762210)+1 种基金Beijing Natural Science Foundation(3204052)Post-doctoral Program for Innovation Talents(BX20180380).
文摘Microseismic data shows that some unconventional reservoirs comprise well-developed natural fractures and complex hydraulic fracture networks.It is neither practical nor advantageous to simulate a huge number of natural and hydraulic fractures with numerical models.Given that the conventional dual-porosity models are not applicable to the highly discrete natural fractures,the paper develops a semianalytical well testing model for horizontal wells with hydraulic fracture networks and randomly-distributed discretely natural fractures.The proposed model has the capability to analyze the pressure behaviors by considering complex fracture networks and isolated natural fractures rapidly and efficiently.The model includes diffusivity equations in three domains:(1)matrix,(2)discretely natural fractures,and(3)hydraulic fracture networks.The pressure transient solution of these diffusivity equations is obtained by using Laplace transforms and super-position principle.We verify the presented model by performing a case study with a numerical simulator for complex natural fractures.It is found that there are some interestingflow behaviors for fracture-network horizontal well with discretely natural fractures like bilinearflow,“V-shape”caused byfluid supply,pseudo boundary-dominatedflow,impact of natural fractures,etc.The pseudo boundary-dominatedflow provides us the information about how large the area covered by hydraulic fracture networks.The impact of natural fracture shows the pa-rameters of natural fractures.This work provides a good understanding of transient pressure behaviors in unconventional reservoirs and guidelines for the producer optimizefield development and well economics.
基金supported by the Scientific Research and Technology Development Project of CNPC“Research and field test of key technologies for effective exploitation of deep shale gas”(No.2019F-31JT).
文摘With the rapid development of shale gas exploration and development in China,casing deformation in shale gas horizontal wells happens frequently,which directly impacts the development efficiency and benefits of shale gas.In order to explore casing deformation prediction,prevention and treatment methods,this paper analyzes the geological and engineering causes of casing deformation in shale-gas horizontal wells through laboratory work,such as the casing resistance to internal pressure alternating test,the ground simulation test and systematical casing deformation characteristic analysis of MIT24 caliper logging,and the large-scale physical simulation test and numerical simulation of casing deformation.Then,combined with the generalized shear activity criterion,a new method for evaluating casing deformation risk points and some technical measures for preventing casing deformation were formulated.And the following research results were obtained.First,the deformation characteristics of 119 casing deformation points in 23 wells interpreted by MIT24 caliper logging are consistent with the mechanical behaviors of shear compression deformation test.Second,the large-scale physical simulation test shows that natural fault-fractures slip obviously under the state of strike-slip stress.Third,numerical simulation shows that the compression stress on casing increases with the increase of fault-fracture slip.When the fault-fracture slip is between 7.5 mm and 9.0 mm,the casing reaches the critical yield strength and begins to undergo plastic deformation.The“temporary fracture plugging+long segment and multi-cluster”and other technologies are field tested in 28 wells in Weiyuan area of southern Sichuan Basin.The casing deformation rate decreases from 54%(before this research)to 14.3%,and the segment loss rate decreases from 7.8%to 0,which reveals remarkable achievements in casing deformation treatment.In conclusion,the shear slip of fault and macro fractures(referred to as fault-fracture)is the main cause of casing deformation in shale gas horizontal wells,and some measures(e.g.“temporary fracture plugging+long segment and multi-cluster”,reducing fracturing scale and releasing wellbore pressure properly)shall be taken in advance to reduce the fault-fracture activity before the risk point of casing deformation is fractured,so as to reach the goal of casing deformation prevention.
基金Project supported by the National Key Basic Research and Development Program(973 Program)“Theory and Technology Adaptability of Shale Gas Development in Typical Marine Blocks in South China”(No.2013CB228006).
文摘Horizontal shale gas well fracturing is mostly carried out by pumping bridge plugs.In the case of casing deformation,the bridge plug can not be pumped down to the designated position,so the hole sections below the deformation could not be stimulated according to the design program.About 30%of horizontal shale gas wells in the Changning and Weiyuan Blocks,Sichuan Basin,suffer various casing deformation after fracturing.Previously,the hole sections which could not be stimulated due to casing deformation were generally abandoned.As a result,the resources controlled by shale gas wells weren't exploited effectively and the fracturing effect was impacted greatly.There are a lot of difficulties in investigating casing deformation,such as complex mechanisms,various influencing factors and unpredictable deformation time.Therefore,it is especially important to seek a staged fracturing technology suitable for the casing deformation sections.In this paper,the staged fracturing technology with sand plugs inside fractures and the staged fracturing technology with temporary plugging balls were tested in casing deformation wells.The staged fracturing technology with sand plugs inside fractures was carried out in the mode of single-stage perforation and single-stage fracturing.The staged fracturing technology with temporary plugging balls was conducted in the mode of single perforation,continuous fracturing and staged ball dropping.Then,two kinds of technologies were compared in terms of their advantages and disadvantages.Finally,they were tested on site.According to the pressure response,the pressure monitoring of the adjacent wells and the microseismic monitoring in the process of actual fracturing,both technologies are effective in the stimulation of the casing deformation sections,realizing well control reserves efficiently and guaranteeing fracturing effects.
基金financially supported by the fund of the Key Projects of Shaanxi Provincial International Technology Cooperation Plan(2013KW16)the Scientific Research Program funded by Shaanxi Provincial Education Department(2013JK0914)+2 种基金the State Key Laboratory of Solidifi cation Processing in NWPU(SKLSP201115)the Scientific Research Project of Xi'an University of Technology(2013CX004)the fund of the Key Laboratory of Electrical Materials and Infi ltration Technology of Shaanxi Province,China(2014)
文摘In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters （i.e. austenitizing temperature and time, and austempering temperature and time） on microstructure and mechanical properties of LZQT500-7 ductile iron dense bars with 172 mm in diameter which were produced by horizontal continuous casting （HCC）. The results show that the major factors influencing the hardness of austempered ductile iron （ADI） are austenitizing temperature and austempering temperature. The fraction of retained austenite increases as the austenitizing and austempering temperatures increase. When austenitizing temperature is low, acicular ferrite and retained austenite can be efifciently obtained by appropriately extending the austenitizing time. The proper austmepering time could ensure enough stability of retained austenite and prevent high carbon austenite decomposition. The optimal mechanical properties of ADI can be achieved with the fol owing process parameters： austenitizing temperature and time are 866 ＆#176;C and 135 min, and austempering temperature and time are 279 ＆#176;C and 135 min, respectively. The microstructure of ADI under the optimal austempering process consists of ifne acicular ferrite and a smal amount of retained austenite, and the hardness, tensile strength, yield strength, elongation and impact toughness of the bars are HBW 476, 1670 MPa, 1428 MPa, 2.93%and 25.7 J, respectively.
基金supported by Central Guiding Local Science and Technology Development Special Fund Project(No.ZYYD2023B02)the National Natural Science Foundation of China(Nos.52078432 and 52168066)the Scientific Research Project of China Railway First Survey and Design Institute Group Co.(No.20-06).
文摘Rock slope with horizontal-layered fractured structure(HLFS)has high stability in its natural state.However,a strong earthquake can induce rock fissure expansion,ultimately leading to slope failure.In this study,the dynamic response,failure mode,and spectral characteristics of rock slope with HLFS under strong earthquake conditions were investigated based on the large-scale shaking table model test.On this basis,multiple sets of numerical calculation models were further established by UDEC discrete element program.Five influencing factors were considered in the parametric study of numerical simulations,including slope height,slope angle,bedding-plane spacing and secondary joint spacing as well as bedrock dip angle.The results showed that the failure process of rock slope with HLFS under earthquake action is mainly divided into four phases,i.e.,the tensile crack of the slope shoulder joints and shear dislocation at the top bedding plane,the extension of vertical joint cracks and increase of shear displacement,the formation of step-through sliding surfaces and the instability,and finally collapse of fractured rock mass.The acceleration response of slopes exhibits elevation amplification effect and surface effect.Numerical simulations indicate that the seismic stability of slopes with HLFS exhibits a negative correlation with slope height and angle,but a positive correlation with bedding-plane spacing,joint spacing,and bedrock dip angle.The results of this study can provide a reference for seismic stability evaluation of weathered rock slopes.
基金supported by the National Natural Science Foundation of China(Nos.51725903 and 52001293)the Taishan Scholar Program of Shandong Province(No.ts20190915).
文摘This research investigates water-wave scattering via a horizontal perforated plate fixed at the still water level through analytical studies and physical model tests.The velocity potential decomposition method is combined with an efficient iterative algorithm to develop an analytical solution in which the quadratic pressure drop condition is imposed on the horizontal perforated plate.The analytical results are in good agreement with the results of an independently developed iterative boundary element method(BEM)solution.Experimental tests are carried out in a wave flume to measure the reflection coefficient and transmission coefficient of the horizontal perforated plate,and the analytical results agree reasonably well with the experimental data.The influence of various structural parameters of the horizontal perforated plate on the hydrodynamic parameters of reflection coefficient,transmission coefficient,energy-loss coefficient,and wave force are analyzed on the basis of the analytical solution.Useful results for the practical engineering application of horizontal perforated plates are also presented.
文摘In this paper, solutions to the 3D transient flow mathematical model for horizontal wells in box-rounded reservoirs are presented. The solutions are derived in Laplace transform domain by employing integral transform and point-source superposition. Both efficient computation of pressure responses and practical technology of oil field application mentioned here may be used to interpret the data from unsteady-state horizontal well testing.
基金supported by the National Major Science and Technology Project“Comprehensive evaluation of horizontal well completion and key technique with high-temperature-resistant and anti-migration slurry”(No.:2016ZX 05021-005-009HZ).
文摘In order to accurately evaluate the fracturing stimulation effect of horizontal wells in shale gas reservoirs,it is suggested to establish a model to predict the temperature distribution in the wellbore of horizontal well and an inversion model of DTS data by using MCMC algorithm,and optimize the production profile interpretation process.In this paper,the characteristics of temperature profile of fractured horizontal wells in shale gas reservoirs were analyzed and the main factors affecting the temperature profile were figured out.Finally,the newly established inversion model was applied to the production profile interpretation of one case well in a certain shale gas reservoir.And the following research results were obtained.First,the temperature profile of fractured horizontal wells is in the shape of irregular“saw tooth”,and each“saw tooth”corresponds to an effective hydraulic fracture with fluid inflow.Second,the longer the fracture is,the greater the wellbore temperature drop at the corresponding fracture location is,and the gas flow rate in the fracture is positively correlated with the temperature drop.Third,from the perspective of influence degree,the factors influencing the temperature profile of fractured horizontal wells in shale gas reservoirs are ranked from the strong to the weak as follows:fracture half-length,gas flow rate,permeability of stimulated area,wellbore diameter,fracture conductivity,horizontal inclination angle,and comprehensive thermal conductivity,among which,the first three are main controlling factors.Fourth,the MCMC inversion method is applied to invert the DST temperature data of the case well.The temperature profile predicted in the model is better accordant with the measured DTS profile,and the absolute error of the predicted temperature at different levels of effective hydraulic fractures is less than 0.02°C.The interpreted gas flow rate of each fracturing stage is closer to the field measurement,and the deviation of the maximum gas flow rate of a single fracturing stage is only 180.35 m^(3)/d.The absolute error between single-well gas production rate and gas production rate measured at the wellhead is less than 3 m^(3)/d,which proves the reliability of this newly developed inversion model.
基金supported by the National Natural Sci-ence Foundation of China(Nos.52201345,and 52001293)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘This study proposes a novel open-type rectangular breakwater combined with horizontal perforated plates on both sides to enhance the sheltering effect of the rectangular box-type breakwaters against longer waves.The hydrodynamic characteristics of this breakwater are analyzed through analytical potential solutions and experimental tests.The quadratic pressure drop conditions are exerted on the horizontal perforated plates to facilitate assessing the effect of wave height on the dissipated wave energy of breakwater through the analytical solution.The hydrodynamic quantities of the breakwater,including the reflection,transmission,and energyloss coefficients,together with vertical and horizontal wave forces,are calculated using the velocity potential decomposition method as well as an iterative algorithm.Furthermore,the reflection and transmission coefficients of the breakwater are measured by conducting experimental tests at various wave periods,wave heights,and both porosities and widths of the horizontal perforated plates.The analytical predicted results demonstrate good agreement with the iterative boundary element method solution and measured data.The influences of variable incident waves and structure parameters on the hydrodynamic characteristics of the breakwater are investigated through further calculations based on analytical solutions.Results indicate that horizontal perforated plates placed on the water surface for both sides of the rectangular breakwater can enhance the wave dissipation ability of the breakwater while effectively decreasing the transmission and reflection coefficients.
