In the context of the global“Carbon Peaking and Carbon Neutrality”initiative,the injection of carbon dioxide(CO_(2))into depleted gas reservoirs represents a dual-purpose strategy—facilitating long-term carbon sequ...In the context of the global“Carbon Peaking and Carbon Neutrality”initiative,the injection of carbon dioxide(CO_(2))into depleted gas reservoirs represents a dual-purpose strategy—facilitating long-term carbon sequestration while enhancing hydrocarbon recovery.However,variations in injection parameters at the wellhead can exert pronounced effects on the temperature and pressure conditions at the bottomof the well.These variations,in turn,influence the geomechanical behavior of reservoir rocks and the displacement efficiency of CO_(2) within the formation.Precise prediction of downhole thermodynamic conditions is therefore essential for optimizing injection performance and ensuring reservoir stability.To address this need,the present study develops a robust coupled model to simulate the behavior of CO_(2) within the wellbore,incorporating momentum conservation,mass continuity,and steady-state heat transfer equations.Validation against field-measured data confirms the model’s reliability and applicability under realworld operating conditions.Parametric analysis reveals the complex influence of injection conditions on bottom-hole states.Injection pressure primarily affects downhole pressure,exerting minimal influence on temperature.In contrast,low injection temperatures and elevated flow rates lead to reduced bottom-hole temperatures and heightened pressures.Owing to the interplay of convective and conductive heat transfer mechanisms,the relationship between injection rate and bottom-hole temperature exhibits nonlinearity.Notably,injection scenarios characterized by low temperature,high pressure,and high velocity promote a deeper penetration of the CO_(2) critical phase transition point within the tubing.Among the parameters examined,injection temperature emerges as the dominant factor affecting the depth of CO_(2)’s phase transformation,followed by injection rate,with pressure exerting the least influence.A strong correlation is observed between injection rate and the depth of the critical phase transition,offering a practical framework for tailoring injection strategies to enhance both CO_(2) storage capacity and recovery efficiency.展开更多
Micro-mesoporous composite molecular sieves H-ZSM-5/MCM-41 were prepared by the hydrothermal technique with alkali-treated H-ZSM-5zeolite as the source and characterized by scanning electron microscopy,transmission el...Micro-mesoporous composite molecular sieves H-ZSM-5/MCM-41 were prepared by the hydrothermal technique with alkali-treated H-ZSM-5zeolite as the source and characterized by scanning electron microscopy,transmission electron microscopy,energy dispersive spectroscopy,X-ray diffraction,N2 adsorption-desorption measurement and NH3 temperature-programmed desorption.The catalytic performances for the methanol dehydration to dimethyl ether over H-ZSM-5/MCM-41 were evaluated.Among these catalysts,H-ZSM-5/MCM-41 prepared with NaOH dosage (nNa/nSi) varying from 0.4 to 0.47 presented excellent catalytic activity with more than 80%methanol conversion and 100%dimethyl ether selectivity in a wide temperature range of 170—300℃,and H-ZSM-5/MCM-41 prepared with nNa/nSi=0.47 showed constant methanol conversion of about 88.7%,100% dimethyl ether selectivity and excellent lifetime at 220℃.The excellent catalytic performances were due to the highly active and uniform acidic sites and the hierarchical porosity in the micro-mesoporous composite molecular sieves.The catalytic mechanism of H-ZSM-5/MCM-41 for the methanol dehydration to dimethyl ether process was also discussed.展开更多
Fibulin-1(FBLN-1),an elastin-associated extracellular matrix protein,has been found in blood and may play a role in the pathophysiological processes leading to cardiovascular disease(CVD).We aimed to investigate the r...Fibulin-1(FBLN-1),an elastin-associated extracellular matrix protein,has been found in blood and may play a role in the pathophysiological processes leading to cardiovascular disease(CVD).We aimed to investigate the relationship between fibulin-1 levels and the risk of CVD by evaluating vascular age derived from the Framingham Heart Study and brachial-ankle Pulse Wave Velocity(baPWV)in patients with asymptomatic hyperuricemia(AHU).In total,66 patients with AHU and 66 gender-and age-matched healthy individuals were enrolled.The plasma fibulin-1 levels were measured by immunochemistry.Patients with AHU presented significantly higher vascular age[median(interquartile range):54(22)vs.48(14)years,P=0.01]and baPWV[mean±SD:1373±223 vs.1291±177 cm/s,P=0.02]than the healthy subjects;however,no significant difference was observed in the plasma fibulin-1 level between the patients with AHU and healthy subjects[median(interquartile range):4018(3838)vs.3099(3405)ng/mL,P=0.31].A correlation between fibulin-1 levels and baPWV was observed only in patients with AHU(r=0.29,P=0.02);and there was also a suggestively statistically significant correlation between fibulin-1 levels and vascular age(r=0.22,P=0.08).However,these associations were rendered insignificant after adjustments for potential confounders.In healthy subjects,no correlation was observed between fibulin-1 levels and CVD risk.This study reveals that plasma fibulin-1 levels may reflect the CVD risk in patients with AHU,but the relationship is not robust.展开更多
We study the statistical property of fast radio bursts(FRBs) based on a selected sample of 190 one-off FRBs in the first CHIME/FRB catalog.Three power law models are used in the analysis,and we find the cumulative dis...We study the statistical property of fast radio bursts(FRBs) based on a selected sample of 190 one-off FRBs in the first CHIME/FRB catalog.Three power law models are used in the analysis,and we find the cumulative distribution functions of energy can be well fitted by bent power law and thresholded power law models.The distribution functions of fluctuations of energy well follow the Tsallis q-Gaussian distribution.The q values in the Tsallis q-Gaussian distribution are constant with small fluctuations for different temporal scale intervals,indicating a scale-invariant structure of the bursts.The earthquakes and soft gamma repeaters show similar properties,which are consistent with the predictions of self-organized criticality systems.展开更多
A method of Standard Site Method (SSM) in the American National Standards Institute’s ANSI C63.5 is described in the frequency ranges from 30 MHz to 1000 MHz. And a measurement system is set up for determining antenn...A method of Standard Site Method (SSM) in the American National Standards Institute’s ANSI C63.5 is described in the frequency ranges from 30 MHz to 1000 MHz. And a measurement system is set up for determining antenna factors (AF) of antennas on an Open Area Test Sites (OATS). AF of antennas including log-periodic antenna and biconical antenna is measured with SSM method by Shanghai Institute of Measurement and Testing Technology (SIMT), which shows good agreement to data measured by National Institute of Metrology (NIM). In the end, it analyzes the measurement uncertainty of SIMT in the 30 MHz to 1000 MHz frequency band and does comparison to that of NIM.展开更多
In this work,we study a direction dependent power spectrum in anisotropic Finsler spacetime. We use this direction dependent power spectrum to address the low-l power observed in WMAP and PLANCK data. The angular powe...In this work,we study a direction dependent power spectrum in anisotropic Finsler spacetime. We use this direction dependent power spectrum to address the low-l power observed in WMAP and PLANCK data. The angular power spectrum of the temperature fluctuations has a lower amplitude in comparison to the ΛCDM model in the multipole range l = 2-40. Our theoretical model gives a correction to the isotropic angular power spectrum Cl^TT ldue to the breaking of rotational invariance of the primordial power spectrum. We estimate best-fit model parameters along with the six ΛCDM cosmological parameters using the PLANCK likelihood code in Cosmo MC software. We find that this modified angular power spectrum fits the CMB temperature data in the multipole range l = 2-10 to a good extent but fails for the whole multipole range l = 2-40.展开更多
Objective: To explore the comparative observation on nursing effect of nursing intervention and routine nursing in patients with renal calculi and gastric ulcer and the impacts on epidermal growth factor. Methods: A t...Objective: To explore the comparative observation on nursing effect of nursing intervention and routine nursing in patients with renal calculi and gastric ulcer and the impacts on epidermal growth factor. Methods: A total of 72 patients with renal calculi and gastric ulcer were selected and treated in our hospital from January 2018 to December 2018. They were divided into the observation group and the control group, 36 for each. Comprehensive nursing intervention was implemented in the observation group, whereas routine nursing was implemented in the control group. The level of epidermal growth factor, nursing satisfaction, renal calculi recurrence rate, average hospital stay and postoperative blood loss were compared between the two groups after nursing. Results: There was no significant difference in the level of epidermal growth factor between the two groups before nursing (P > 0.05), while after nursing, the level in the observation group was higher compared with the control group, and the difference between the two groups was significant (P Conclusion: With regard to patients with renal calculi and gastric ulcer, comprehensive nursing intervention can improve nursing satisfaction and quality of patients’ lives, reduce calculi recurrence rate, and increase the level of epidermal growth factor, which has clinical application value.展开更多
The time series of energy and waiting time in magnetar bursts carry important information about the source activity.In this study,we investigate the memory and dynamical stability of magnetar bursts from four soft gam...The time series of energy and waiting time in magnetar bursts carry important information about the source activity.In this study,we investigate the memory and dynamical stability of magnetar bursts from four soft gamma repeater(SGR)sources:SGR 1806−20,SGR 1900+14,SGR J1935+2154,and SGR J1550−5418.Based on the rescaled range analysis,we quantify the memory in magnetar bursts for the first time and find that there exists long-term memory in the time series of both waiting time and energy.We investigate the dynamical stability in the context of randomness and chaos.For all four SGR samples,we find that the waiting time is not completely random;however,the energy of two SGRs is consistent with a total random organization.Furthermore,both waiting time and energy exhibit weak chaos.We also find no significant difference between SGRs and repeating fast radio bursts(FRBs)in the randomness-chaos phase space.The statistical similarity between SGRs and repeating FRBs hints that there may be potential physical connection between these two phenomena.展开更多
The propagation of wormhole is vital important for matrix acidizing and acid fracturing in carbonate reservoirs.While the formation of acid dissolved wormhole is derived from heterogeneous physical and chemical transp...The propagation of wormhole is vital important for matrix acidizing and acid fracturing in carbonate reservoirs.While the formation of acid dissolved wormhole is derived from heterogeneous physical and chemical transportations and reactions.Alveolate dissolved pores,krast caves,and natural fissures are the major reservoir spaces for the Sinian dolomite formation in the Anyue gas field of the Sichuan Basin.There were four categories of formation,which are matrix dominated,inter-breccia dissolved pore dominated,dissolved pore and cave dominated,and fissure and cave dominated,based on the development intensity and connectedness of caves and fissures.The caves and fissures make the wormhole formation and propagation particularly complicated.Firstly,the 3-D topological structure of dissolved pores,vugs,fissures and throats inside cores is quantitatively scanned by CT imaging technology for its feature of vivid and damage-free.Secondly,3-D patterns of wormhole are obtained with CT scanning after core flooding by acid.Additionally,the porethroat network model is reconstructed with digital cores technology.Then,the size and ratio of pore and throat before and after core flooding by acid is analyzed and the absolute permeability of pore scale flow is numerically simulated to understand the fundamental influence of pores and vugs distribution and connectedness on wormhole propagation.Lastly,the wormhole pattern gained by CT scanning and simulating with two-scale model is compared.Meanwhile,the corrected two-scale model is utilized to simulate the wormhole propagation for matrix acidizing and acid fracturing of Sinian fractured-vuggy dolomite in Anyue gas field,Sichuan Basin.The optimized injection rate and volume were in agreement with the characteristic matrix acidizing operating curve,which indicates that the two-scale model was suitable for matrix acidizing optimization design of such formations.In addition,the simulated acid etched fracture length with considering the dynamic wormhole leakoff was consistent with the well testing interpreted result.展开更多
The brittleness index plays a significant role in the hydraulic fracturing design and wellbore stability analysis of shale reservoirs.Various brittleness indices have been proposed to characterize the brittleness of s...The brittleness index plays a significant role in the hydraulic fracturing design and wellbore stability analysis of shale reservoirs.Various brittleness indices have been proposed to characterize the brittleness of shale rocks,but almost all of them ignored the anisotropy of the brittleness index.Therefore,uniaxial compression testing integrated with geophysical logging was used to provide insights into the anisotropy of the brittleness index for Longmaxi shale,the presented method was utilized to assess brittleness index of Longmaxi shale formation for the interval of 3155e3175 m in CW-1 well.The results indicated that the brittleness index of Longmaxi shale showed a distinct anisotropy,and it achieved the minimum value at β=45°-60°.As the bedding angle increased,the observed brittleness index(BI_(2_β))decreased firstly and increased then,it achieved the lowest value at β=40°-60°,and it is consistent with the uniaxial compression testing results.Compared to the isotropic brittleness index(β=0°),the deviation of the anisotropic brittleness index ranged from 10%to 66.7%,in other words,the anisotropy of brittleness index cannot be ignored for Longmaxi shale.Organic matter content is one of the main intrinsic causes of shale anisotropy,and the anisotropy degree of the brittleness index generally increases with the increase in organic matter content.The present work is valuable for the assessment of anisotropic brittleness for hydraulic fracturing design and wellbore stability analysis.展开更多
We propose that fast radio bursts(FRBs)can be used as probes to constrain the possible anisotropic distribution of baryon matter in the Universe.Monte Carlo simulations show that 400(800)FRBs are sufficient to detect ...We propose that fast radio bursts(FRBs)can be used as probes to constrain the possible anisotropic distribution of baryon matter in the Universe.Monte Carlo simulations show that 400(800)FRBs are sufficient to detect the anisotropy at a 95%(99%)confidence level if the dipole amplitude has an order of magnitude of 0.01.However,more FRBs are required to tightly constrain the dipole direction.Even 1000 FRBs are insufficient to constrain the dipole direction within the angular uncertainty △θ<40°at a 95%confidence level.The uncertainty on the dispersion measure of a host galaxy does not significantly affect the results.However,if the dipole amplitude is in the region of 0.001,1000 FRBs are not enough to correctly detect the anisotropic signal.展开更多
To address the problems of lack of high-frequency information and texture details and unstable training in superresolution generative adversarial net-works,this paper optimizes the generator and discriminator based on...To address the problems of lack of high-frequency information and texture details and unstable training in superresolution generative adversarial net-works,this paper optimizes the generator and discriminator based on the SRGAN model.First,the residual dense block is used as the basic structural unit of the gen-erator to improve the network’s feature extraction capability.Second,enhanced lightweight coordinate attention is incorporated to help the network more precisely concentrate on high-frequency location information,thereby allowing the gener-ator to produce more realistic image reconstruction results.Then,we propose a symmetric and efficient pyramidal segmentation attention discriminator network in which the attention mechanism is capable of derivingfiner-grained multiscale spatial information and creating long-term dependencies between multiscale chan-nel attentions,thus enhancing the discriminative ability of the network.Finally,a Charbonnier loss function and a gradient variance loss function with improved robustness are used to better realize the image’s texture structure and enhance the model’s stability.Thefindings from the experiments reveal that the reconstructed image quality enhances the average peak signal-to-noise ratio(PSNR)by 1.59 dB and the structural similarity index(SSIM)by 0.045 when compared to SRGAN on the three test sets.Compared with the state-of-the-art methods,the reconstructed images have a clearer texture structure,richer high-frequency details,and better visual effects.展开更多
The superresolution(SR)method based on generative adversarial networks(GANs)cannot adequately capture enough diversity from training data,resulting in misalignment between input low resolution(LR)images and output hig...The superresolution(SR)method based on generative adversarial networks(GANs)cannot adequately capture enough diversity from training data,resulting in misalignment between input low resolution(LR)images and output high resolution(HR)images.GAN training has difficulty converging.Based on this,an advanced GAN-based image SR reconstructionmethod is presented.First,the dense connection residual block and attention mechanism are integrated into the GAN generator to improve high-frequency feature extraction.Meanwhile,an added discriminator is added into the GAN discriminant network,which forms a dual discriminator to ensure that the process of training is stable.Second,the more robust Charbonnier loss is used instead of the mean square error(MSE)loss to compare similarities between the obtained image and actual image,and the total variation(TV)loss is employed to smooth the training results.Finally,the experimental results indicate that global structures can be better reconstructed using the method of this paper and texture details of images compared with other SOTA methods.The peak signal-to-noise ratio(PSNR)values by the method of this paper are improved by an average of 2.24 dB,and the structural similarity index measure(SSIM)values are improved by an average of 0.07.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52304046,52204051,52174033 and U23B20156).
文摘In the context of the global“Carbon Peaking and Carbon Neutrality”initiative,the injection of carbon dioxide(CO_(2))into depleted gas reservoirs represents a dual-purpose strategy—facilitating long-term carbon sequestration while enhancing hydrocarbon recovery.However,variations in injection parameters at the wellhead can exert pronounced effects on the temperature and pressure conditions at the bottomof the well.These variations,in turn,influence the geomechanical behavior of reservoir rocks and the displacement efficiency of CO_(2) within the formation.Precise prediction of downhole thermodynamic conditions is therefore essential for optimizing injection performance and ensuring reservoir stability.To address this need,the present study develops a robust coupled model to simulate the behavior of CO_(2) within the wellbore,incorporating momentum conservation,mass continuity,and steady-state heat transfer equations.Validation against field-measured data confirms the model’s reliability and applicability under realworld operating conditions.Parametric analysis reveals the complex influence of injection conditions on bottom-hole states.Injection pressure primarily affects downhole pressure,exerting minimal influence on temperature.In contrast,low injection temperatures and elevated flow rates lead to reduced bottom-hole temperatures and heightened pressures.Owing to the interplay of convective and conductive heat transfer mechanisms,the relationship between injection rate and bottom-hole temperature exhibits nonlinearity.Notably,injection scenarios characterized by low temperature,high pressure,and high velocity promote a deeper penetration of the CO_(2) critical phase transition point within the tubing.Among the parameters examined,injection temperature emerges as the dominant factor affecting the depth of CO_(2)’s phase transformation,followed by injection rate,with pressure exerting the least influence.A strong correlation is observed between injection rate and the depth of the critical phase transition,offering a practical framework for tailoring injection strategies to enhance both CO_(2) storage capacity and recovery efficiency.
基金supported by the National Nature Science Foundation of China (No: 20976013)International Science & Technology Cooperation Program of China (No: 2012DFR40240)
文摘Micro-mesoporous composite molecular sieves H-ZSM-5/MCM-41 were prepared by the hydrothermal technique with alkali-treated H-ZSM-5zeolite as the source and characterized by scanning electron microscopy,transmission electron microscopy,energy dispersive spectroscopy,X-ray diffraction,N2 adsorption-desorption measurement and NH3 temperature-programmed desorption.The catalytic performances for the methanol dehydration to dimethyl ether over H-ZSM-5/MCM-41 were evaluated.Among these catalysts,H-ZSM-5/MCM-41 prepared with NaOH dosage (nNa/nSi) varying from 0.4 to 0.47 presented excellent catalytic activity with more than 80%methanol conversion and 100%dimethyl ether selectivity in a wide temperature range of 170—300℃,and H-ZSM-5/MCM-41 prepared with nNa/nSi=0.47 showed constant methanol conversion of about 88.7%,100% dimethyl ether selectivity and excellent lifetime at 220℃.The excellent catalytic performances were due to the highly active and uniform acidic sites and the hierarchical porosity in the micro-mesoporous composite molecular sieves.The catalytic mechanism of H-ZSM-5/MCM-41 for the methanol dehydration to dimethyl ether process was also discussed.
文摘Fibulin-1(FBLN-1),an elastin-associated extracellular matrix protein,has been found in blood and may play a role in the pathophysiological processes leading to cardiovascular disease(CVD).We aimed to investigate the relationship between fibulin-1 levels and the risk of CVD by evaluating vascular age derived from the Framingham Heart Study and brachial-ankle Pulse Wave Velocity(baPWV)in patients with asymptomatic hyperuricemia(AHU).In total,66 patients with AHU and 66 gender-and age-matched healthy individuals were enrolled.The plasma fibulin-1 levels were measured by immunochemistry.Patients with AHU presented significantly higher vascular age[median(interquartile range):54(22)vs.48(14)years,P=0.01]and baPWV[mean±SD:1373±223 vs.1291±177 cm/s,P=0.02]than the healthy subjects;however,no significant difference was observed in the plasma fibulin-1 level between the patients with AHU and healthy subjects[median(interquartile range):4018(3838)vs.3099(3405)ng/mL,P=0.31].A correlation between fibulin-1 levels and baPWV was observed only in patients with AHU(r=0.29,P=0.02);and there was also a suggestively statistically significant correlation between fibulin-1 levels and vascular age(r=0.22,P=0.08).However,these associations were rendered insignificant after adjustments for potential confounders.In healthy subjects,no correlation was observed between fibulin-1 levels and CVD risk.This study reveals that plasma fibulin-1 levels may reflect the CVD risk in patients with AHU,but the relationship is not robust.
基金supported by the National Natural Science Foundation of China under Grant Nos.12005184 and 12005183the Natural Science Foundation of the Jiangsu Higher Education Institutions of China under Grant No.20KJD140002。
文摘We study the statistical property of fast radio bursts(FRBs) based on a selected sample of 190 one-off FRBs in the first CHIME/FRB catalog.Three power law models are used in the analysis,and we find the cumulative distribution functions of energy can be well fitted by bent power law and thresholded power law models.The distribution functions of fluctuations of energy well follow the Tsallis q-Gaussian distribution.The q values in the Tsallis q-Gaussian distribution are constant with small fluctuations for different temporal scale intervals,indicating a scale-invariant structure of the bursts.The earthquakes and soft gamma repeaters show similar properties,which are consistent with the predictions of self-organized criticality systems.
文摘A method of Standard Site Method (SSM) in the American National Standards Institute’s ANSI C63.5 is described in the frequency ranges from 30 MHz to 1000 MHz. And a measurement system is set up for determining antenna factors (AF) of antennas on an Open Area Test Sites (OATS). AF of antennas including log-periodic antenna and biconical antenna is measured with SSM method by Shanghai Institute of Measurement and Testing Technology (SIMT), which shows good agreement to data measured by National Institute of Metrology (NIM). In the end, it analyzes the measurement uncertainty of SIMT in the 30 MHz to 1000 MHz frequency band and does comparison to that of NIM.
基金funded by the National Natural Science Foundation of China (Grant Nos.11375203,11675182 and 11690022)
文摘In this work,we study a direction dependent power spectrum in anisotropic Finsler spacetime. We use this direction dependent power spectrum to address the low-l power observed in WMAP and PLANCK data. The angular power spectrum of the temperature fluctuations has a lower amplitude in comparison to the ΛCDM model in the multipole range l = 2-40. Our theoretical model gives a correction to the isotropic angular power spectrum Cl^TT ldue to the breaking of rotational invariance of the primordial power spectrum. We estimate best-fit model parameters along with the six ΛCDM cosmological parameters using the PLANCK likelihood code in Cosmo MC software. We find that this modified angular power spectrum fits the CMB temperature data in the multipole range l = 2-10 to a good extent but fails for the whole multipole range l = 2-40.
文摘Objective: To explore the comparative observation on nursing effect of nursing intervention and routine nursing in patients with renal calculi and gastric ulcer and the impacts on epidermal growth factor. Methods: A total of 72 patients with renal calculi and gastric ulcer were selected and treated in our hospital from January 2018 to December 2018. They were divided into the observation group and the control group, 36 for each. Comprehensive nursing intervention was implemented in the observation group, whereas routine nursing was implemented in the control group. The level of epidermal growth factor, nursing satisfaction, renal calculi recurrence rate, average hospital stay and postoperative blood loss were compared between the two groups after nursing. Results: There was no significant difference in the level of epidermal growth factor between the two groups before nursing (P > 0.05), while after nursing, the level in the observation group was higher compared with the control group, and the difference between the two groups was significant (P Conclusion: With regard to patients with renal calculi and gastric ulcer, comprehensive nursing intervention can improve nursing satisfaction and quality of patients’ lives, reduce calculi recurrence rate, and increase the level of epidermal growth factor, which has clinical application value.
基金Supported by the National Natural Science Fund of China(12005184,12175192,12275034,12347101)the Fundamental Research Funds for the Central Universities of China(2024CDJXY-022)。
文摘The time series of energy and waiting time in magnetar bursts carry important information about the source activity.In this study,we investigate the memory and dynamical stability of magnetar bursts from four soft gamma repeater(SGR)sources:SGR 1806−20,SGR 1900+14,SGR J1935+2154,and SGR J1550−5418.Based on the rescaled range analysis,we quantify the memory in magnetar bursts for the first time and find that there exists long-term memory in the time series of both waiting time and energy.We investigate the dynamical stability in the context of randomness and chaos.For all four SGR samples,we find that the waiting time is not completely random;however,the energy of two SGRs is consistent with a total random organization.Furthermore,both waiting time and energy exhibit weak chaos.We also find no significant difference between SGRs and repeating fast radio bursts(FRBs)in the randomness-chaos phase space.The statistical similarity between SGRs and repeating FRBs hints that there may be potential physical connection between these two phenomena.
基金The authors are grateful for the research support of the Postdoctoral Program of Postdoctoral Work Centre,Southwest Oil&Gas Field Company(No.20150304-08).
文摘The propagation of wormhole is vital important for matrix acidizing and acid fracturing in carbonate reservoirs.While the formation of acid dissolved wormhole is derived from heterogeneous physical and chemical transportations and reactions.Alveolate dissolved pores,krast caves,and natural fissures are the major reservoir spaces for the Sinian dolomite formation in the Anyue gas field of the Sichuan Basin.There were four categories of formation,which are matrix dominated,inter-breccia dissolved pore dominated,dissolved pore and cave dominated,and fissure and cave dominated,based on the development intensity and connectedness of caves and fissures.The caves and fissures make the wormhole formation and propagation particularly complicated.Firstly,the 3-D topological structure of dissolved pores,vugs,fissures and throats inside cores is quantitatively scanned by CT imaging technology for its feature of vivid and damage-free.Secondly,3-D patterns of wormhole are obtained with CT scanning after core flooding by acid.Additionally,the porethroat network model is reconstructed with digital cores technology.Then,the size and ratio of pore and throat before and after core flooding by acid is analyzed and the absolute permeability of pore scale flow is numerically simulated to understand the fundamental influence of pores and vugs distribution and connectedness on wormhole propagation.Lastly,the wormhole pattern gained by CT scanning and simulating with two-scale model is compared.Meanwhile,the corrected two-scale model is utilized to simulate the wormhole propagation for matrix acidizing and acid fracturing of Sinian fractured-vuggy dolomite in Anyue gas field,Sichuan Basin.The optimized injection rate and volume were in agreement with the characteristic matrix acidizing operating curve,which indicates that the two-scale model was suitable for matrix acidizing optimization design of such formations.In addition,the simulated acid etched fracture length with considering the dynamic wormhole leakoff was consistent with the well testing interpreted result.
基金supported by the post-doctoral project of Petrochina Southwest Oil&Gas Field Company“Research on Deep Shale Geomechanics and Effective Fracturing Factors”(Grant No.20210302-31)the Program of Introducing Talents of Discipline to Chinese Universities(111 Plan)(Grant No.D18016)+2 种基金the Sichuan Science and Technology Program(Grant No.2020JDJQ0055)the Nanchong-SWPU Science and Technology Strategic Cooperation Foundation(Grant No.SXHZ033)the Youth Scientific and Technological Innovation Team Foundation of SWPU(Grant No.2019CXTD09).
文摘The brittleness index plays a significant role in the hydraulic fracturing design and wellbore stability analysis of shale reservoirs.Various brittleness indices have been proposed to characterize the brittleness of shale rocks,but almost all of them ignored the anisotropy of the brittleness index.Therefore,uniaxial compression testing integrated with geophysical logging was used to provide insights into the anisotropy of the brittleness index for Longmaxi shale,the presented method was utilized to assess brittleness index of Longmaxi shale formation for the interval of 3155e3175 m in CW-1 well.The results indicated that the brittleness index of Longmaxi shale showed a distinct anisotropy,and it achieved the minimum value at β=45°-60°.As the bedding angle increased,the observed brittleness index(BI_(2_β))decreased firstly and increased then,it achieved the lowest value at β=40°-60°,and it is consistent with the uniaxial compression testing results.Compared to the isotropic brittleness index(β=0°),the deviation of the anisotropic brittleness index ranged from 10%to 66.7%,in other words,the anisotropy of brittleness index cannot be ignored for Longmaxi shale.Organic matter content is one of the main intrinsic causes of shale anisotropy,and the anisotropy degree of the brittleness index generally increases with the increase in organic matter content.The present work is valuable for the assessment of anisotropic brittleness for hydraulic fracturing design and wellbore stability analysis.
基金Supported by the National Natural Science Foundation of China(11603005,11775038,12005184)。
文摘We propose that fast radio bursts(FRBs)can be used as probes to constrain the possible anisotropic distribution of baryon matter in the Universe.Monte Carlo simulations show that 400(800)FRBs are sufficient to detect the anisotropy at a 95%(99%)confidence level if the dipole amplitude has an order of magnitude of 0.01.However,more FRBs are required to tightly constrain the dipole direction.Even 1000 FRBs are insufficient to constrain the dipole direction within the angular uncertainty △θ<40°at a 95%confidence level.The uncertainty on the dispersion measure of a host galaxy does not significantly affect the results.However,if the dipole amplitude is in the region of 0.001,1000 FRBs are not enough to correctly detect the anisotropic signal.
基金This work was supported in part by the Basic Scientific Research Project of Liaoning Provincial Department of Education under Grant Nos.LJKQZ2021152 and LJ2020JCL007in part by the National Science Foundation of China(NSFC)under Grant No.61602226in part by the PhD Startup Foundation of Liaoning Technical University of China under Grant Nos.18-1021.
文摘To address the problems of lack of high-frequency information and texture details and unstable training in superresolution generative adversarial net-works,this paper optimizes the generator and discriminator based on the SRGAN model.First,the residual dense block is used as the basic structural unit of the gen-erator to improve the network’s feature extraction capability.Second,enhanced lightweight coordinate attention is incorporated to help the network more precisely concentrate on high-frequency location information,thereby allowing the gener-ator to produce more realistic image reconstruction results.Then,we propose a symmetric and efficient pyramidal segmentation attention discriminator network in which the attention mechanism is capable of derivingfiner-grained multiscale spatial information and creating long-term dependencies between multiscale chan-nel attentions,thus enhancing the discriminative ability of the network.Finally,a Charbonnier loss function and a gradient variance loss function with improved robustness are used to better realize the image’s texture structure and enhance the model’s stability.Thefindings from the experiments reveal that the reconstructed image quality enhances the average peak signal-to-noise ratio(PSNR)by 1.59 dB and the structural similarity index(SSIM)by 0.045 when compared to SRGAN on the three test sets.Compared with the state-of-the-art methods,the reconstructed images have a clearer texture structure,richer high-frequency details,and better visual effects.
基金supported in part by the Basic Scientific Research Project of Liaoning Provincial Department of Education under Grant No.LJKQZ2021152in part by the National Science Foundation of China (NSFC)under Grant No.61602226in part by the PhD Startup Foundation of Liaoning Technical University of China under Grant No.18-1021.
文摘The superresolution(SR)method based on generative adversarial networks(GANs)cannot adequately capture enough diversity from training data,resulting in misalignment between input low resolution(LR)images and output high resolution(HR)images.GAN training has difficulty converging.Based on this,an advanced GAN-based image SR reconstructionmethod is presented.First,the dense connection residual block and attention mechanism are integrated into the GAN generator to improve high-frequency feature extraction.Meanwhile,an added discriminator is added into the GAN discriminant network,which forms a dual discriminator to ensure that the process of training is stable.Second,the more robust Charbonnier loss is used instead of the mean square error(MSE)loss to compare similarities between the obtained image and actual image,and the total variation(TV)loss is employed to smooth the training results.Finally,the experimental results indicate that global structures can be better reconstructed using the method of this paper and texture details of images compared with other SOTA methods.The peak signal-to-noise ratio(PSNR)values by the method of this paper are improved by an average of 2.24 dB,and the structural similarity index measure(SSIM)values are improved by an average of 0.07.
