The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that o...The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional reservoirs.At the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not applicable.In this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is established.Then,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface roughness.The flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.展开更多
BACKGROUND Multitudinous advancements have been made to the traditional microfracture(MFx)technique,which have involved delivery of various acellular 2nd generation MFx and cellular MFx-III components to the area of c...BACKGROUND Multitudinous advancements have been made to the traditional microfracture(MFx)technique,which have involved delivery of various acellular 2nd generation MFx and cellular MFx-III components to the area of cartilage defect.The relative benefits and pitfalls of these diverse modifications of MFx technique are still not widely understood.AIM To comparatively analyze the functional,radiological,and histological outcomes,and complications of various generations of MFx available for the treatment of cartilage defects.METHODS A systematic review was performed using PubMed,EMBASE,Web of Science,Cochrane,and Scopus.Patients of any age and sex with cartilage defects undergoing any form of MFx were considered for analysis.We included only randomized controlled trials(RCTs)reporting functional,radiological,histological outcomes or complications of various generations of MFx for the management of cartilage defects.Network meta-analysis(NMA)was conducted in Stata and Cochrane’s Confidence in NMA approach was utilized for appraisal of evidence.RESULTS Forty-four RCTs were included in the analysis with patients of mean age of 39.40(±9.46)years.Upon comparing the results of the other generations with MFX-I as a constant comparator,we noted a trend towards better pain control and functional outcome(KOOS,IKDC,and Cincinnati scores)at the end of 1-,2-,and 5-year time points with MFx-III,although the differences were not statistically significant(P>0.05).We also noted statistically significant Magnetic resonance observation of cartilage repair tissue score in the higher generations of microfracture(weighted mean difference:17.44,95%confidence interval:0.72,34.16,P=0.025;without significant heterogeneity)at 1 year.However,the difference was not maintained at 2 years.There was a trend towards better defect filling on MRI with the second and third generation MFx,although the difference was not statistically significant(P>0.05).CONCLUSION The higher generations of traditional MFx technique utilizing acellular and cellular components to augment its potential in the management of cartilage defects has shown only marginal improvement in the clinical and radiological outcomes.展开更多
Objective:To evaluate the clinical efficacy of combining arthroscopic patellar denervation with microfracture in the treatment of patellofemoral arthritis under cold weather conditions.Methods:A total of 134 patients ...Objective:To evaluate the clinical efficacy of combining arthroscopic patellar denervation with microfracture in the treatment of patellofemoral arthritis under cold weather conditions.Methods:A total of 134 patients with patellofemoral arthritis who underwent treatment between June 2019 and June 2021 were included in this study.Patients were randomly divided into two groups:the control group,which received standard arthroscopic debridement and conventional therapy,and the study group,which underwent additional peripatellar denervation and microfracture procedures.Clinical outcomes,including Tegner scores,hospital for special surgery(HSS)scores,and treatment-related adverse events,were evaluated and compared between the two groups.Results:The study group achieved a significantly higher excellent treatment rate(95.52%,64/67)compared to the control group.Post-treatment Tegner scores(5.48±1.86)and HSS scores(86.37±11.25)were also significantly better in the study group than in the control group.Furthermore,the incidence of adverse reactions was lower in the study group(4.48%,3/67),with statistically significant differences observed(P<0.05).Conclusions:Arthroscopic patellar denervation combined with microfracture markedly improves clinical outcomes,including Tegner and HSS scores,in the treatment of patellofemoral arthritis,particularly under cold weather conditions.The procedure is effective and safe,supporting its broader clinical application.展开更多
A high-precision microseismic(MS)monitoring system was built to monitor surrounding rock microfractures in the underground powerhouse on the left bank of Shuangjiangkou Hydropower Station.The surrounding rock damage a...A high-precision microseismic(MS)monitoring system was built to monitor surrounding rock microfractures in the underground powerhouse on the left bank of Shuangjiangkou Hydropower Station.The surrounding rock damage area with spatiotemporal clustering of MS activities was studied for qualitative analysis of the damage mechanism of surrounding rock microfractures,based on the source parameters of MS events.The surrounding rock microfracture scale characterized by the source radius of MS events was considered to establish the constitutive relation.MS information was imported into the model for numerical analysis using fast Lagrangian analysis of continuain 3 dimensions(FLAC^(3D)).The results indicated that the numerical simulation results considering MS damage can better reflect the actual situation of the field.The surrounding rock microfractures mainly showed mixed failure characteristics.Shear failures appeared in localized areas while the fracture scale of sections from K0e33 m to K0e15 m on the vault was large.The deformation increment caused by microfracture damage in the shallow surrounding rock of the top arch accounted for 10%e13%,and the stress decrement in the surrounding rock caused by microfracture damage accounted for about 10%.展开更多
The Euphrates Graben is located in eastern Syria.The Upper Triassic Mulussa F Formation sandstones serve as the primary reservoir intervals in the majority of the graben fields.The study’s findings were based on core...The Euphrates Graben is located in eastern Syria.The Upper Triassic Mulussa F Formation sandstones serve as the primary reservoir intervals in the majority of the graben fields.The study’s findings were based on core studies:petrographic examination of thin sections,scanning electron microscope(SEM),imaging of backscatter scanning electron microscope(BSE),X-ray microprobe examinations,and carbon-oxygen stable isotope analysis of microfracture-filling cements.Three of the most common types of microfracture found in the investigated sandstones are intragranular or intracrystalline microfractures,grain boundary or grain-edge microfractures,and transgranular(crossing grains)microfractures.Sandstone microfractures that are open and free of secondary mineralization improve sandstone storage and permeability.However,microfractures that are cemented and filled with secondary mineralization reduce storage and permeability.Common siderite and pyrite cements were identified within the microfractures and the nearby sandstone matrix.Larger anhedral or euhedral siderites are thought to form during shallow burial diagenesis,whereas poikilotopic siderites are thought to form during deep burial diagenesis.Poikilotopic pyrite is believed to be a diagenetic cement,which is attributed to the reduction of iron oxides present in the sediments in the presence of hydrocarbons.Microfractures reflect tectonic,overpressure,and diagenetic origins.Microfractures of tectonic origin are associated with folding and thrust activities over the Euphrates Graben area,and they were formed at the beginning of the Upper Triassic with siderite and pyrite cement equilibration temperatures of approximately 100–105℃,and they continued forming from the middle to the end of the Upper Triassic with cement equilibration temperatures of approximately 90–100℃in conjunction with the first phase of the Euphrates Graben.Microfractures related to diagenetic and overpressure processes are tension microfractures and were formed in compression settings during the Upper Triassic.展开更多
The limited intrinsic healing potential of human articular cartilage is a well-known problem in orthopedic surgery. Thus a variety of surgical techniques have been developed to reduce joint pain, improve joint functio...The limited intrinsic healing potential of human articular cartilage is a well-known problem in orthopedic surgery. Thus a variety of surgical techniques have been developed to reduce joint pain, improve joint function and delay the onset of osteoarthritis. Microfractures as a bone marrow stimulation technique present the most common applied articular cartilage repair procedure today. Unfortunately the deficiencies of fibrocartilaginous repair tissue inevitably lead to breakdown under normal joint loading and clinical results deteriorate with time. To overcome the shortcomings of microfracture, an enhanced microfracture technique was developed with an additional collagen Ⅰ/Ⅲ membrane(Autologous, Matrix-Induced Chondrogenesis, AMIC). This article reviews the pre-clinical rationale of microfractures and AMIC, presents clinical studies and shows the advantages and disadvantages of these widely usedtechniques. PubM ed and the Cochrane database were searched to identify relevant studies. We used a comprehensive search strategy with no date or language restrictions to locate studies that examined the AMIC technique and microfracture. Search keywords included cartilage, microfracture, AMIC, knee, ChondroGide. Besides this, we included our own experiences and study authors were contacted if more and non published data were needed. Both cartilage repair techniques represent an effective and safe method of treating full-thickness chondral defects of the knee in selected cases. While results after microfracture deteriorate with time, mid-term results after AMIC seem to be enduring. Randomized studies with long-term followup are needed whether the grafted area will maintain functional improvement and structural integrity over time.展开更多
Based on the rock typing method of pore geometry and structure(PGS), rock samples from carbonate reservoir A and carbonate reservoir B were classified using data of routine and special core analysis and thin section i...Based on the rock typing method of pore geometry and structure(PGS), rock samples from carbonate reservoir A and carbonate reservoir B were classified using data of routine and special core analysis and thin section images, and microfractures in the carbonate reservoir samples were identified and characterized. Establishment of rock types demonstrates that microfractures have developed in all rock types in carbonate reservoir A, but only partially in certain rock types in carbonate reservoir B with porosity of 1%–11%, less vuggy, and hardness of medium hard to hard. The cut-off porosity was determined for each type of rock to distinguish samples with and without conductive microfractures. The impact of conductive microfractures on improving permeability was analyzed. On the basis of relationship of permeability and original initial water saturation, the permeability equation was derived by certain special core analysis data with conductive microfractures selected by PGS equation, and the permeability of samples with conductive microfractures has been successfully predicted.展开更多
Relationship among deformation history,fracture process and stress distribution of granular bainite has been investigated.The main process of fracture of granular bainite is the forma- tion.growth and coalescence of t...Relationship among deformation history,fracture process and stress distribution of granular bainite has been investigated.The main process of fracture of granular bainite is the forma- tion.growth and coalescence of the microvoids.Even though the microcracks have formed at the earlier stage of deformation,they are not fateful for fracture because in the successive deformation stage the microcracks change their orientation toward the tensile axis.The strain hardening rate of granular bainite has a minimal value during the deformation process. Before and after the strain of the minimal value,the material shows different stress distribu- tion and microfracture mechanism.展开更多
Objective:To investigate the feasibility of minimal invasive repair of cartilage defect by arthroscope-aided microfracture surgery and autologous transplantation of mesenchymal stem cells. Methods: Bone marrow of mini...Objective:To investigate the feasibility of minimal invasive repair of cartilage defect by arthroscope-aided microfracture surgery and autologous transplantation of mesenchymal stem cells. Methods: Bone marrow of minipigs was taken out and the bone marrow derived mesenchymal stem cells (BMSCs) were isolated and cultured to passage 3. Then 6 minipigs were randomly divided into 2 groups with 6 knees in each group. After the articular cartilage defect was induced in each knee, the left defect received microfracture surgery and was injected with 2.5 ml BMSCs cells at a concentration of 3×107 cells/ml into the articular cavity; while right knee got single microfracture or served as blank control group. The animals were killed at 8 or 16 weeks, and the repair tissue was histologically and immunohistochemically examined for the presence of type Ⅱ collagen and glycosaminoglycans (GAGs) at 8 and 16 weeks. Results: Eight weeks after the surgery, the overlying articular surface of the cartilage defect showed normal color and integrated to adjacent cartilage. And 16 weeks after surgery, hyaline cartilage was observed at the repairing tissues and immunostaining indicated the diffuse presence of this type Ⅱ collagen and GAGs throughout the repair cartilage in the treated defects. Single microfracture group had the repairing of fibrocartilage, while during the treatment, the defects of blank group were covered with fewer fiber tissues, and no blood capillary growth or any immunological rejection was observed. Conclusion: Microfracture technique and BMSCs transplantation to repair cartilage defect is characterized with minimal invasion and easy operation, and it will greatly promote the regeneration repair of articular cartilage defect.展开更多
Based on the comprehensive understanding on microfractures and matrix pores in reservoir rocks,numerical algorithms are used to construct fractured porous media and fracture-pore media models.Connectivity coefficient ...Based on the comprehensive understanding on microfractures and matrix pores in reservoir rocks,numerical algorithms are used to construct fractured porous media and fracture-pore media models.Connectivity coefficient and strike factor are introduced into the models to quantitatively characterize the connectivity and strike of fracture network,respectively.The influences of fracture aperture,fracture strike and fracture connectivity on the permeability of porous media are studied by using multi-relaxation-time lattice Boltzmann model to simulate fluid flow in them.The greater the strike factor and the smaller the tortuosity of the fractured porous media,the greater the permeability of the fractured porous media.The greater the connectivity coefficient of the fracture network is,the greater the permeability of the fracture-pore media is,and the more likely dominant channel effect occurs.The fracture network connectivity has stronger influence on seepage ability of fracture-pore media than fracture aperture and fracture strike.The tortuosity and strike factor of fracture network in fractured porous media are in polynomial relation,while the permeability and fracture network connectivity coefficient of the fracture-pore media meet an exponential relation.展开更多
When subchondral bone defects are present in osteochondral lesions of the talus(OCLT),it is inconclusive whether to allow early weightbearing after microfracture treatment because of the lack of effective support of t...When subchondral bone defects are present in osteochondral lesions of the talus(OCLT),it is inconclusive whether to allow early weightbearing after microfracture treatment because of the lack of effective support of the newly-formed fibrocartilage.After performing arthroscopic debridement and microfracture treatment on OCLT patients with subchondral bone defects,we allowed patients to have an early postoperative weightbearing exercise to observe their clinical outcome.Forty-two OCLT patients with subchondral bone defects were analyzed.Patients were randomly divided into two groups with 21 patients in each group.After arthroscopic debridement and microfracture treatment,group A was allowed to have early partial weightbearing while weightbearing was delayed in group B.Visual analogue scale(VAS)was used to evaluate joint pain before and after surgery.American Orthopaedic Foot and Ankle Society(AOFAS)anklc-hindfoot score was used to evaluate joint function.Tegner activity scale was used to assess patient's exercise level.The AOFAS ankle-hindfoot score in group A increased from 54.4 to 87.6,and that in group B increased from 54.9 to 87.3.The VAS score in group A decreased from 6.5 to 2.2,and that in group B decreased from 6.4 to 2.3.The Tegner activity scale increased from 2.6 to 4.4 in group A,and that in group B increased from 2.6 to 3.9.There was significant difference in the Tegner activity scale between group A and group B(P<0.05).It was suggested that when performing microfracture treatmenf on OCLT patients with subchondral bone defects,early postoperative weightbearing may achieve similar clinical outcomes as delayed weightbearing,and patients may be better able to return to sports.展开更多
Fluid invasion through fractures is frequently observed in subsurface engineering. To elucidate the microkinetic behavior of fracture fluids, the microfracture structure of coal from the Surat Basin was reconstructed ...Fluid invasion through fractures is frequently observed in subsurface engineering. To elucidate the microkinetic behavior of fracture fluids, the microfracture structure of coal from the Surat Basin was reconstructed using a 3D morphometric system and stitching algorithm, then the transparent models characterizing the fracture structure were produced using microfluidics, and water invasion in the microfracture model was measured via visualization experiments under various conditions. High flow rate facilitated the invasion of the water phase into the closed channel, improving the efficiency of water invasion in the neutral wetting system. Wettability reversal changed the dominant channel for water invasion in the hydrophobic system. The invasion efficiency in closed and small aperture bypass channels was low.The reduction of effective seepage channels led to the fastest breakthrough time. Higher surface tension and interfacial curvature promoted the hysteresis effect. The reduction of effective seepage channels led to the fastest breakthrough time. The larger surface tension and interfacial curvature make the hysteresis effect more significant. These results will enable a better understanding of the rock-gas-liquid multiphase interaction mechanisms under unsaturated conditions of rocks.展开更多
Traditionally physicians have advised patients to be non-weight bearing post arthroscopic knee microfracture surgery for at least 2 to 8 weeks. The microfracture procedure is a simple, low-risk method to induce self-c...Traditionally physicians have advised patients to be non-weight bearing post arthroscopic knee microfracture surgery for at least 2 to 8 weeks. The microfracture procedure is a simple, low-risk method to induce self-cartilage regeneration to focal lesions. The procedure has shown that small fractures to the subchondral bone can recruit mesenchymal stem cells and growth factors to regenerate the fibrocartilage without compromising the subchondral plate. With the simplicity of this procedure and the positive effect it can have on patients, it is natural to want to push the bounds of rehabilitation to see what is necessary. The patient in this case report exhibits the potential for positive outcomes with early weight-bearing status in patients receiving microfractures via subchondral drilling. This positive outcome, along with others, should encourage clinicians to consider reestablishing evidence-guided rehabilitation post microfracture with new studies. Shortened rehabilitation time would decrease a barrier to surgery for many patients and would only enhance our treatment with this surgical modality.展开更多
Fractures in organic-rich shale are important reservoir spaces and seepage channels of shale gas,and they are closely related to the gas-bearing properties of shale.The development characteristics and laws of fracture...Fractures in organic-rich shale are important reservoir spaces and seepage channels of shale gas,and they are closely related to the gas-bearing properties of shale.The development characteristics and laws of fractures are of great significance in the exploration and development of shale oil and gas.This study examines organic-rich shales of the WufengeLongmaxi Formation in the Weiyuan area of the Sichuan Basin.On the basis of two-dimensional large-area multi-scale combination electron microscopy characterization and digital core platform technology,the development degree and distribution of different fractures are quantitatively characterized.The results show the following.(1)The shale of the Wufeng and Longmaxi formations developed a variety of fractures with different occurrences,sizes,and origins.According to the number and combination relationship between fractures of different occurrences,the shale can be divided into four fracture combination types:horizontal bedding fractures;vein fractures;reticular fractures;and ring fractures.Of these,the horizontal bedding fracture group has the largest number of samples and a higher average fracture surface porosity.(2)The degree of fracture development in the shale is affected by many factors,such as the laminar type,mineral composition,mineral particle size,mineral distribution,and total organic carbon,and the controlling mechanisms of different fracture combination types differ.Factors such as horizontal stratification,high clay mineral content,and uneven mineral particle size are conducive to the development of horizontal bedding joints.(3)Differences in the sedimentary environment affect the variation laws of the vertical fracture combination types and density.The total organic carbon and organic quartz content of the Long111 layer with deeper sedimentary water is higher,and the vein fracture formation is more developed than in other small layers,while the clay mineral content of the Long112 and Long114 layers with shallower sedimentary water is higher and the horizontal layer is more developed;the fracture combination type is dominated by the horizontal bedding fracture combination.At the same time,the fractures at the junction of each layer of the Long11 sub-member are the most developed because sea level rise and fall make the mineral particle size heterogeneity most prominent at the junction of the small layer.展开更多
Articular cartilage repair and regeneration is still a significant challenge despite years of research.Although microfracture techniques are commonly used in clinical practice,the newborn cartilage is usually fibrocar...Articular cartilage repair and regeneration is still a significant challenge despite years of research.Although microfracture techniques are commonly used in clinical practice,the newborn cartilage is usually fibrocartilage rather than hyaline cartilage,which is mainly attributed to the inadequate microenvironment for effectively recruiting,anchoring,and inducing bone marrow mesenchymal stem cells(BMSCs)to differentiate into hyaline cartilage.This paper introduces a novel cartilage acellular matrix(CACM)microgel assembly with excellent microporosity,injectability,tissue adhesion,BMSCs recruitment and chondrogenic differentiation capabilities to improve the microfracture-based articular cartilage regeneration.Specifically,the sustained release of simva-statin(SIM)from the SIM@CACM microgel assembly efficiently recruits BMSCs in the early stage of cartilage regeneration,while the abundant interconnected micropores and high specific area assure the quick adhesion,proliferation and infiltration of BMSCs.Additionally,the active factors within the CACM matrix,appropriate mechanical properties of the microgel assembly,and excellent tissue adhesion provide a conductive environment for the continuous chondrogenic differentiation of BMSCs into hyaline cartilage.Owing to the synergistic effect of the above-mentioned factors,good articular cartilage repair and regeneration is achieved.展开更多
Sphenoidal tensile microfractures with particular patterns have been discovered in the Late Devonian quartzose sandstone in islands and peninsula of the Taihu Lake area. Microfractures present a ‘?’-shape collective...Sphenoidal tensile microfractures with particular patterns have been discovered in the Late Devonian quartzose sandstone in islands and peninsula of the Taihu Lake area. Microfractures present a ‘?’-shape collective pattern, occurring in a single row or multiple rows. The quartz crystals in the inner acute angle area of some ‘?’-shape microfractures have severely been non-crystallized, showing the feature of diaplectic glass. The studies show that these special microfractures were formed during the unloading process after the compression was up to the peak of an impact event.展开更多
The temporal and spatial distribution of microfracturing activity in two kinds of granite under triaxial compression has been studied by using a new acoustic emission system. For Inada granite, there is no clear clust...The temporal and spatial distribution of microfracturing activity in two kinds of granite under triaxial compression has been studied by using a new acoustic emission system. For Inada granite, there is no clear clustering of acoustic emission events in time and space, thus it is difficult to exactly deduce the time and position of the major fracturing. While for Mayet granite,acoustic emission events are clustered in time and space, so the time and position of the major fracturing can be exactly predicted according to microfracturing process. Such a difference may result from the difference in deformation mode caused by different rock structures.展开更多
The Pabdeh Formation represents organic matter enrichment in some oil fields,which can be considered a source rock.This study is based on the Rock–Eval,Iatroscan,and electron microscopy imaging results before and aft...The Pabdeh Formation represents organic matter enrichment in some oil fields,which can be considered a source rock.This study is based on the Rock–Eval,Iatroscan,and electron microscopy imaging results before and after heating the samples.We discovered this immature shale that undergoes burial and diagenesis,in which organic matter is converted into hydro-carbons.Primary migration is the process that transports hydrocarbons in the source rock.We investigated this phenomenon by developing a model that simulates hydrocarbon generation and fluid pressure during kerogen-to-hydrocarbon conversion.Microfractures initially formed at the tip/edge of kerogen and were filled with hydrocarbons,but as catagenesis progressed,the pressure caused by the volume increase of kerogen decreased due to hydrocarbon release.The transformation of solid kerogen into low-density bitumen/oil increased the pressure,leading to the development of damage zones in the source rock.The Pabdeh Formation’s small porethroats hindered effective expulsion,causing an increase in pore fluid pressure inside the initial microfractures.The stress accumulated due to hydrocarbon production,reaching the rock’s fracture strength,further contributed to damage zone development.During the expansion process,microfractures preferentially grew in low-strength pathways such as lithology changes,laminae boundaries,and pre-existing microfractures.When the porous pressure created by each kerogen overlapped,individual microfractures interconnected,forming a network of microfractures within the source rock.This research sheds light on the complex interplay between temperature,hydrocarbon generation,and the development of expulsion fractures in the Pabdeh Formation,providing valuable insights for understanding and optimizing hydrocarbon extraction in similar geological settings.展开更多
Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures(MPFS)of coal is paramount for ensuring the secure extraction of coa...Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures(MPFS)of coal is paramount for ensuring the secure extraction of coal resources.This study conducts cyclic loading-unloading and creep experiments on coal using a low-field nuclear magnetic resonance(NMR)experimental apparatus which is equipped with mechanical loading units,enabling real-time monitoring the T2spectrum.The experiments indicated that cyclic loading-unloading stress paths initiate internal damage within coal samples.Under identical creep stress conditions,coal samples with more initial damages had more substantial instantaneous deformation and creep deformation during the creep process.After undergoing nearly 35 h of staged creep,the total strains for coal samples CC01,CC02,and CC03 reach 2.160%,2.261%,and 2.282%,respectively.In the creep stage,the peak area ratio of seepage pores and microfractures(SPM)gradually diminishes.A higher degree of initial damage leads to a more pronounced compaction trend in the SPM of coal samples.Considering the porosity evolution of SPM during the creep process,this study proposes a novel fractional derivative model for the porosity evolution of SPM.The efficacy of the proposed model in predicting porosity evolution of SPM is substantiated through experimental validation.Furthermore,an analysis of the impact mechanisms on key parameters in the model was carried out.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52022087).
文摘The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional reservoirs.At the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not applicable.In this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is established.Then,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface roughness.The flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.
文摘BACKGROUND Multitudinous advancements have been made to the traditional microfracture(MFx)technique,which have involved delivery of various acellular 2nd generation MFx and cellular MFx-III components to the area of cartilage defect.The relative benefits and pitfalls of these diverse modifications of MFx technique are still not widely understood.AIM To comparatively analyze the functional,radiological,and histological outcomes,and complications of various generations of MFx available for the treatment of cartilage defects.METHODS A systematic review was performed using PubMed,EMBASE,Web of Science,Cochrane,and Scopus.Patients of any age and sex with cartilage defects undergoing any form of MFx were considered for analysis.We included only randomized controlled trials(RCTs)reporting functional,radiological,histological outcomes or complications of various generations of MFx for the management of cartilage defects.Network meta-analysis(NMA)was conducted in Stata and Cochrane’s Confidence in NMA approach was utilized for appraisal of evidence.RESULTS Forty-four RCTs were included in the analysis with patients of mean age of 39.40(±9.46)years.Upon comparing the results of the other generations with MFX-I as a constant comparator,we noted a trend towards better pain control and functional outcome(KOOS,IKDC,and Cincinnati scores)at the end of 1-,2-,and 5-year time points with MFx-III,although the differences were not statistically significant(P>0.05).We also noted statistically significant Magnetic resonance observation of cartilage repair tissue score in the higher generations of microfracture(weighted mean difference:17.44,95%confidence interval:0.72,34.16,P=0.025;without significant heterogeneity)at 1 year.However,the difference was not maintained at 2 years.There was a trend towards better defect filling on MRI with the second and third generation MFx,although the difference was not statistically significant(P>0.05).CONCLUSION The higher generations of traditional MFx technique utilizing acellular and cellular components to augment its potential in the management of cartilage defects has shown only marginal improvement in the clinical and radiological outcomes.
基金supported by grants from the Natural Science Foundation of Heilongjiang Province of China(JQ2020H003)Heilongjiang Postdoctoral Fund(NO.LBH-Z23257)+1 种基金the Innovative Science Research Fund of Harbin Medical University(also known as Heilongjiang Provincial University's Project of Graduate Scientific Research Business Fees)(2022-KYYWF-0274)the Youth TCM scientific research Project of Heilongjiang Province TCM Administration(ZHY2024-283).
文摘Objective:To evaluate the clinical efficacy of combining arthroscopic patellar denervation with microfracture in the treatment of patellofemoral arthritis under cold weather conditions.Methods:A total of 134 patients with patellofemoral arthritis who underwent treatment between June 2019 and June 2021 were included in this study.Patients were randomly divided into two groups:the control group,which received standard arthroscopic debridement and conventional therapy,and the study group,which underwent additional peripatellar denervation and microfracture procedures.Clinical outcomes,including Tegner scores,hospital for special surgery(HSS)scores,and treatment-related adverse events,were evaluated and compared between the two groups.Results:The study group achieved a significantly higher excellent treatment rate(95.52%,64/67)compared to the control group.Post-treatment Tegner scores(5.48±1.86)and HSS scores(86.37±11.25)were also significantly better in the study group than in the control group.Furthermore,the incidence of adverse reactions was lower in the study group(4.48%,3/67),with statistically significant differences observed(P<0.05).Conclusions:Arthroscopic patellar denervation combined with microfracture markedly improves clinical outcomes,including Tegner and HSS scores,in the treatment of patellofemoral arthritis,particularly under cold weather conditions.The procedure is effective and safe,supporting its broader clinical application.
基金support from the National Key R&D Program of China(Grant No.2017YFC1501100)the Science Foundation for Distinguished Young Scholars of Sichuan Province(Grant No.2020JDJQ0011)the National Natural Science Foundation of China(Grant No.42177143).
文摘A high-precision microseismic(MS)monitoring system was built to monitor surrounding rock microfractures in the underground powerhouse on the left bank of Shuangjiangkou Hydropower Station.The surrounding rock damage area with spatiotemporal clustering of MS activities was studied for qualitative analysis of the damage mechanism of surrounding rock microfractures,based on the source parameters of MS events.The surrounding rock microfracture scale characterized by the source radius of MS events was considered to establish the constitutive relation.MS information was imported into the model for numerical analysis using fast Lagrangian analysis of continuain 3 dimensions(FLAC^(3D)).The results indicated that the numerical simulation results considering MS damage can better reflect the actual situation of the field.The surrounding rock microfractures mainly showed mixed failure characteristics.Shear failures appeared in localized areas while the fracture scale of sections from K0e33 m to K0e15 m on the vault was large.The deformation increment caused by microfracture damage in the shallow surrounding rock of the top arch accounted for 10%e13%,and the stress decrement in the surrounding rock caused by microfracture damage accounted for about 10%.
基金supported by the Ministry of Science and Higher Education of the Russian Federation under the agreement within the framework of the development program for a world-class research center“Efficient Development of the Global Liquid Hydrocarbon Reserves”(No.075-15-2020-931)。
文摘The Euphrates Graben is located in eastern Syria.The Upper Triassic Mulussa F Formation sandstones serve as the primary reservoir intervals in the majority of the graben fields.The study’s findings were based on core studies:petrographic examination of thin sections,scanning electron microscope(SEM),imaging of backscatter scanning electron microscope(BSE),X-ray microprobe examinations,and carbon-oxygen stable isotope analysis of microfracture-filling cements.Three of the most common types of microfracture found in the investigated sandstones are intragranular or intracrystalline microfractures,grain boundary or grain-edge microfractures,and transgranular(crossing grains)microfractures.Sandstone microfractures that are open and free of secondary mineralization improve sandstone storage and permeability.However,microfractures that are cemented and filled with secondary mineralization reduce storage and permeability.Common siderite and pyrite cements were identified within the microfractures and the nearby sandstone matrix.Larger anhedral or euhedral siderites are thought to form during shallow burial diagenesis,whereas poikilotopic siderites are thought to form during deep burial diagenesis.Poikilotopic pyrite is believed to be a diagenetic cement,which is attributed to the reduction of iron oxides present in the sediments in the presence of hydrocarbons.Microfractures reflect tectonic,overpressure,and diagenetic origins.Microfractures of tectonic origin are associated with folding and thrust activities over the Euphrates Graben area,and they were formed at the beginning of the Upper Triassic with siderite and pyrite cement equilibration temperatures of approximately 100–105℃,and they continued forming from the middle to the end of the Upper Triassic with cement equilibration temperatures of approximately 90–100℃in conjunction with the first phase of the Euphrates Graben.Microfractures related to diagenetic and overpressure processes are tension microfractures and were formed in compression settings during the Upper Triassic.
文摘The limited intrinsic healing potential of human articular cartilage is a well-known problem in orthopedic surgery. Thus a variety of surgical techniques have been developed to reduce joint pain, improve joint function and delay the onset of osteoarthritis. Microfractures as a bone marrow stimulation technique present the most common applied articular cartilage repair procedure today. Unfortunately the deficiencies of fibrocartilaginous repair tissue inevitably lead to breakdown under normal joint loading and clinical results deteriorate with time. To overcome the shortcomings of microfracture, an enhanced microfracture technique was developed with an additional collagen Ⅰ/Ⅲ membrane(Autologous, Matrix-Induced Chondrogenesis, AMIC). This article reviews the pre-clinical rationale of microfractures and AMIC, presents clinical studies and shows the advantages and disadvantages of these widely usedtechniques. PubM ed and the Cochrane database were searched to identify relevant studies. We used a comprehensive search strategy with no date or language restrictions to locate studies that examined the AMIC technique and microfracture. Search keywords included cartilage, microfracture, AMIC, knee, ChondroGide. Besides this, we included our own experiences and study authors were contacted if more and non published data were needed. Both cartilage repair techniques represent an effective and safe method of treating full-thickness chondral defects of the knee in selected cases. While results after microfracture deteriorate with time, mid-term results after AMIC seem to be enduring. Randomized studies with long-term followup are needed whether the grafted area will maintain functional improvement and structural integrity over time.
基金P3MI Bandung Institute of Technology for providing the financial support to conduct this study。
文摘Based on the rock typing method of pore geometry and structure(PGS), rock samples from carbonate reservoir A and carbonate reservoir B were classified using data of routine and special core analysis and thin section images, and microfractures in the carbonate reservoir samples were identified and characterized. Establishment of rock types demonstrates that microfractures have developed in all rock types in carbonate reservoir A, but only partially in certain rock types in carbonate reservoir B with porosity of 1%–11%, less vuggy, and hardness of medium hard to hard. The cut-off porosity was determined for each type of rock to distinguish samples with and without conductive microfractures. The impact of conductive microfractures on improving permeability was analyzed. On the basis of relationship of permeability and original initial water saturation, the permeability equation was derived by certain special core analysis data with conductive microfractures selected by PGS equation, and the permeability of samples with conductive microfractures has been successfully predicted.
文摘Relationship among deformation history,fracture process and stress distribution of granular bainite has been investigated.The main process of fracture of granular bainite is the forma- tion.growth and coalescence of the microvoids.Even though the microcracks have formed at the earlier stage of deformation,they are not fateful for fracture because in the successive deformation stage the microcracks change their orientation toward the tensile axis.The strain hardening rate of granular bainite has a minimal value during the deformation process. Before and after the strain of the minimal value,the material shows different stress distribu- tion and microfracture mechanism.
基金Supported by the National Natural Science Foundation ofChina (No. 30070224)the Key Project of the ScientificResearch Foundation for Medical Science and Public Healthof PLA(No. 01Z072)
文摘Objective:To investigate the feasibility of minimal invasive repair of cartilage defect by arthroscope-aided microfracture surgery and autologous transplantation of mesenchymal stem cells. Methods: Bone marrow of minipigs was taken out and the bone marrow derived mesenchymal stem cells (BMSCs) were isolated and cultured to passage 3. Then 6 minipigs were randomly divided into 2 groups with 6 knees in each group. After the articular cartilage defect was induced in each knee, the left defect received microfracture surgery and was injected with 2.5 ml BMSCs cells at a concentration of 3×107 cells/ml into the articular cavity; while right knee got single microfracture or served as blank control group. The animals were killed at 8 or 16 weeks, and the repair tissue was histologically and immunohistochemically examined for the presence of type Ⅱ collagen and glycosaminoglycans (GAGs) at 8 and 16 weeks. Results: Eight weeks after the surgery, the overlying articular surface of the cartilage defect showed normal color and integrated to adjacent cartilage. And 16 weeks after surgery, hyaline cartilage was observed at the repairing tissues and immunostaining indicated the diffuse presence of this type Ⅱ collagen and GAGs throughout the repair cartilage in the treated defects. Single microfracture group had the repairing of fibrocartilage, while during the treatment, the defects of blank group were covered with fewer fiber tissues, and no blood capillary growth or any immunological rejection was observed. Conclusion: Microfracture technique and BMSCs transplantation to repair cartilage defect is characterized with minimal invasion and easy operation, and it will greatly promote the regeneration repair of articular cartilage defect.
基金Supported by the Science and Technology Major Project of PetroChina(2016E-06)National Natural Science Foundation of China(U1562217)。
文摘Based on the comprehensive understanding on microfractures and matrix pores in reservoir rocks,numerical algorithms are used to construct fractured porous media and fracture-pore media models.Connectivity coefficient and strike factor are introduced into the models to quantitatively characterize the connectivity and strike of fracture network,respectively.The influences of fracture aperture,fracture strike and fracture connectivity on the permeability of porous media are studied by using multi-relaxation-time lattice Boltzmann model to simulate fluid flow in them.The greater the strike factor and the smaller the tortuosity of the fractured porous media,the greater the permeability of the fractured porous media.The greater the connectivity coefficient of the fracture network is,the greater the permeability of the fracture-pore media is,and the more likely dominant channel effect occurs.The fracture network connectivity has stronger influence on seepage ability of fracture-pore media than fracture aperture and fracture strike.The tortuosity and strike factor of fracture network in fractured porous media are in polynomial relation,while the permeability and fracture network connectivity coefficient of the fracture-pore media meet an exponential relation.
文摘When subchondral bone defects are present in osteochondral lesions of the talus(OCLT),it is inconclusive whether to allow early weightbearing after microfracture treatment because of the lack of effective support of the newly-formed fibrocartilage.After performing arthroscopic debridement and microfracture treatment on OCLT patients with subchondral bone defects,we allowed patients to have an early postoperative weightbearing exercise to observe their clinical outcome.Forty-two OCLT patients with subchondral bone defects were analyzed.Patients were randomly divided into two groups with 21 patients in each group.After arthroscopic debridement and microfracture treatment,group A was allowed to have early partial weightbearing while weightbearing was delayed in group B.Visual analogue scale(VAS)was used to evaluate joint pain before and after surgery.American Orthopaedic Foot and Ankle Society(AOFAS)anklc-hindfoot score was used to evaluate joint function.Tegner activity scale was used to assess patient's exercise level.The AOFAS ankle-hindfoot score in group A increased from 54.4 to 87.6,and that in group B increased from 54.9 to 87.3.The VAS score in group A decreased from 6.5 to 2.2,and that in group B decreased from 6.4 to 2.3.The Tegner activity scale increased from 2.6 to 4.4 in group A,and that in group B increased from 2.6 to 3.9.There was significant difference in the Tegner activity scale between group A and group B(P<0.05).It was suggested that when performing microfracture treatmenf on OCLT patients with subchondral bone defects,early postoperative weightbearing may achieve similar clinical outcomes as delayed weightbearing,and patients may be better able to return to sports.
基金Projects(52174159, 52074169, 52174026, 51904167, 52004146) supported by the National Nature Science Foundation of ChinaProject(ZR2020QE102) supported by the Natural Science Foundation Youth Branch of Shandong Province,ChinaProject(SKLMRDPC21KF06) supported by the Open Fund for State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,China。
文摘Fluid invasion through fractures is frequently observed in subsurface engineering. To elucidate the microkinetic behavior of fracture fluids, the microfracture structure of coal from the Surat Basin was reconstructed using a 3D morphometric system and stitching algorithm, then the transparent models characterizing the fracture structure were produced using microfluidics, and water invasion in the microfracture model was measured via visualization experiments under various conditions. High flow rate facilitated the invasion of the water phase into the closed channel, improving the efficiency of water invasion in the neutral wetting system. Wettability reversal changed the dominant channel for water invasion in the hydrophobic system. The invasion efficiency in closed and small aperture bypass channels was low.The reduction of effective seepage channels led to the fastest breakthrough time. Higher surface tension and interfacial curvature promoted the hysteresis effect. The reduction of effective seepage channels led to the fastest breakthrough time. The larger surface tension and interfacial curvature make the hysteresis effect more significant. These results will enable a better understanding of the rock-gas-liquid multiphase interaction mechanisms under unsaturated conditions of rocks.
文摘Traditionally physicians have advised patients to be non-weight bearing post arthroscopic knee microfracture surgery for at least 2 to 8 weeks. The microfracture procedure is a simple, low-risk method to induce self-cartilage regeneration to focal lesions. The procedure has shown that small fractures to the subchondral bone can recruit mesenchymal stem cells and growth factors to regenerate the fibrocartilage without compromising the subchondral plate. With the simplicity of this procedure and the positive effect it can have on patients, it is natural to want to push the bounds of rehabilitation to see what is necessary. The patient in this case report exhibits the potential for positive outcomes with early weight-bearing status in patients receiving microfractures via subchondral drilling. This positive outcome, along with others, should encourage clinicians to consider reestablishing evidence-guided rehabilitation post microfracture with new studies. Shortened rehabilitation time would decrease a barrier to surgery for many patients and would only enhance our treatment with this surgical modality.
基金supported by the National Natural Science Foundation Youth Fund project(Grant No.42302175).
文摘Fractures in organic-rich shale are important reservoir spaces and seepage channels of shale gas,and they are closely related to the gas-bearing properties of shale.The development characteristics and laws of fractures are of great significance in the exploration and development of shale oil and gas.This study examines organic-rich shales of the WufengeLongmaxi Formation in the Weiyuan area of the Sichuan Basin.On the basis of two-dimensional large-area multi-scale combination electron microscopy characterization and digital core platform technology,the development degree and distribution of different fractures are quantitatively characterized.The results show the following.(1)The shale of the Wufeng and Longmaxi formations developed a variety of fractures with different occurrences,sizes,and origins.According to the number and combination relationship between fractures of different occurrences,the shale can be divided into four fracture combination types:horizontal bedding fractures;vein fractures;reticular fractures;and ring fractures.Of these,the horizontal bedding fracture group has the largest number of samples and a higher average fracture surface porosity.(2)The degree of fracture development in the shale is affected by many factors,such as the laminar type,mineral composition,mineral particle size,mineral distribution,and total organic carbon,and the controlling mechanisms of different fracture combination types differ.Factors such as horizontal stratification,high clay mineral content,and uneven mineral particle size are conducive to the development of horizontal bedding joints.(3)Differences in the sedimentary environment affect the variation laws of the vertical fracture combination types and density.The total organic carbon and organic quartz content of the Long111 layer with deeper sedimentary water is higher,and the vein fracture formation is more developed than in other small layers,while the clay mineral content of the Long112 and Long114 layers with shallower sedimentary water is higher and the horizontal layer is more developed;the fracture combination type is dominated by the horizontal bedding fracture combination.At the same time,the fractures at the junction of each layer of the Long11 sub-member are the most developed because sea level rise and fall make the mineral particle size heterogeneity most prominent at the junction of the small layer.
基金financially sponsored by the Key Research and Development Program of Guangdong Province(2023B0909020003)the National Natural Science Foundation of China(Grant Nos.52473130,32071321).
文摘Articular cartilage repair and regeneration is still a significant challenge despite years of research.Although microfracture techniques are commonly used in clinical practice,the newborn cartilage is usually fibrocartilage rather than hyaline cartilage,which is mainly attributed to the inadequate microenvironment for effectively recruiting,anchoring,and inducing bone marrow mesenchymal stem cells(BMSCs)to differentiate into hyaline cartilage.This paper introduces a novel cartilage acellular matrix(CACM)microgel assembly with excellent microporosity,injectability,tissue adhesion,BMSCs recruitment and chondrogenic differentiation capabilities to improve the microfracture-based articular cartilage regeneration.Specifically,the sustained release of simva-statin(SIM)from the SIM@CACM microgel assembly efficiently recruits BMSCs in the early stage of cartilage regeneration,while the abundant interconnected micropores and high specific area assure the quick adhesion,proliferation and infiltration of BMSCs.Additionally,the active factors within the CACM matrix,appropriate mechanical properties of the microgel assembly,and excellent tissue adhesion provide a conductive environment for the continuous chondrogenic differentiation of BMSCs into hyaline cartilage.Owing to the synergistic effect of the above-mentioned factors,good articular cartilage repair and regeneration is achieved.
基金This work was supported by the National Natural Sc ence Foundation of China (Grant No.469672101)
文摘Sphenoidal tensile microfractures with particular patterns have been discovered in the Late Devonian quartzose sandstone in islands and peninsula of the Taihu Lake area. Microfractures present a ‘?’-shape collective pattern, occurring in a single row or multiple rows. The quartz crystals in the inner acute angle area of some ‘?’-shape microfractures have severely been non-crystallized, showing the feature of diaplectic glass. The studies show that these special microfractures were formed during the unloading process after the compression was up to the peak of an impact event.
文摘The temporal and spatial distribution of microfracturing activity in two kinds of granite under triaxial compression has been studied by using a new acoustic emission system. For Inada granite, there is no clear clustering of acoustic emission events in time and space, thus it is difficult to exactly deduce the time and position of the major fracturing. While for Mayet granite,acoustic emission events are clustered in time and space, so the time and position of the major fracturing can be exactly predicted according to microfracturing process. Such a difference may result from the difference in deformation mode caused by different rock structures.
文摘The Pabdeh Formation represents organic matter enrichment in some oil fields,which can be considered a source rock.This study is based on the Rock–Eval,Iatroscan,and electron microscopy imaging results before and after heating the samples.We discovered this immature shale that undergoes burial and diagenesis,in which organic matter is converted into hydro-carbons.Primary migration is the process that transports hydrocarbons in the source rock.We investigated this phenomenon by developing a model that simulates hydrocarbon generation and fluid pressure during kerogen-to-hydrocarbon conversion.Microfractures initially formed at the tip/edge of kerogen and were filled with hydrocarbons,but as catagenesis progressed,the pressure caused by the volume increase of kerogen decreased due to hydrocarbon release.The transformation of solid kerogen into low-density bitumen/oil increased the pressure,leading to the development of damage zones in the source rock.The Pabdeh Formation’s small porethroats hindered effective expulsion,causing an increase in pore fluid pressure inside the initial microfractures.The stress accumulated due to hydrocarbon production,reaching the rock’s fracture strength,further contributed to damage zone development.During the expansion process,microfractures preferentially grew in low-strength pathways such as lithology changes,laminae boundaries,and pre-existing microfractures.When the porous pressure created by each kerogen overlapped,individual microfractures interconnected,forming a network of microfractures within the source rock.This research sheds light on the complex interplay between temperature,hydrocarbon generation,and the development of expulsion fractures in the Pabdeh Formation,providing valuable insights for understanding and optimizing hydrocarbon extraction in similar geological settings.
基金the National Science Fund for Distinguished Young Scholars(No.52225403)the Natural Science Foundation of Shanxi Province(No.202303021212073)the National Natural Science Foundation of China(No.52104210)。
文摘Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures(MPFS)of coal is paramount for ensuring the secure extraction of coal resources.This study conducts cyclic loading-unloading and creep experiments on coal using a low-field nuclear magnetic resonance(NMR)experimental apparatus which is equipped with mechanical loading units,enabling real-time monitoring the T2spectrum.The experiments indicated that cyclic loading-unloading stress paths initiate internal damage within coal samples.Under identical creep stress conditions,coal samples with more initial damages had more substantial instantaneous deformation and creep deformation during the creep process.After undergoing nearly 35 h of staged creep,the total strains for coal samples CC01,CC02,and CC03 reach 2.160%,2.261%,and 2.282%,respectively.In the creep stage,the peak area ratio of seepage pores and microfractures(SPM)gradually diminishes.A higher degree of initial damage leads to a more pronounced compaction trend in the SPM of coal samples.Considering the porosity evolution of SPM during the creep process,this study proposes a novel fractional derivative model for the porosity evolution of SPM.The efficacy of the proposed model in predicting porosity evolution of SPM is substantiated through experimental validation.Furthermore,an analysis of the impact mechanisms on key parameters in the model was carried out.
