BACKGROUND Complicated crown–root fracture (CRF) involves severe injury to the crown, root,and pulp, and may be accompanied by multiple root fractures. The loss of a toothhas lifelong consequences for children and te...BACKGROUND Complicated crown–root fracture (CRF) involves severe injury to the crown, root,and pulp, and may be accompanied by multiple root fractures. The loss of a toothhas lifelong consequences for children and teenagers, but the maintenance of pulphealth and the calcific healing of multiple root fractures are rarely reported in theliterature.CASE SUMMARY This case reports healing of a permanent tooth with complicated crown–root andadditional root fractures, in which pulp health was maintained. A 10-year-old girlfell and fractured the root of her maxillary left central incisor at the cervical level.After the coronal fragment was repositioned, the tooth was splinted until thetooth was no longer mobile, 2 years later. Eight years after treatment, the toothhas remained asymptomatic with vital pulp and localized gingival overgrowth.Cone-beam computed tomography revealed not only calcified healing of the CRFbut also spontaneous healing in an additional undiagnosed root fracture. Thefracture line on the enamel could not be healed by hard tissue and formed agroove in the cervical crown. It was speculated that the groove was related to thelocalized gingival overgrowth.CONCLUSION This case provides a clinical perspective of the treatment of a tooth with acomplicated CRF and an additional root fracture.展开更多
To analyze the differences in the transport and distribution of different types of proppants and to address issues such as the short effective support of proppant and poor placement in hydraulically intersecting fract...To analyze the differences in the transport and distribution of different types of proppants and to address issues such as the short effective support of proppant and poor placement in hydraulically intersecting fractures,this study considered the combined impact of geological-engineering factors on conductivity.Using reservoir production parameters and the discrete elementmethod,multispherical proppants were constructed.Additionally,a 3D fracture model,based on the specified conditions of the L block,employed coupled(Computational Fluid Dynamics)CFD-DEM(Discrete ElementMethod)for joint simulations to quantitatively analyze the transport and placement patterns of multispherical proppants in intersecting fractures.Results indicate that turbulent kinetic energy is an intrinsic factor affecting proppant transport.Moreover,the efficiency of placement and migration distance of low-sphericity quartz sand constructed by the DEM in the main fracture are significantly reduced compared to spherical ceramic proppants,with a 27.7%decrease in the volume fraction of the fracture surface,subsequently affecting the placement concentration and damaging fracture conductivity.Compared to small-angle fractures,controlling artificial and natural fractures to expand at angles of 45°to 60°increases the effective support length by approximately 20.6%.During hydraulic fracturing of gas wells,ensuring the fracture support area and post-closure conductivity can be achieved by controlling the sphericity of proppants and adjusting the perforation direction to control the direction of artificial fractures.展开更多
BACKGROUND Traumatic injuries,such as falling,car accidents,and crushing mostly cause spinal fractures in young and middle-aged people,and>50%of them are thoracolumbar fractures.This kind of fracture is easily comb...BACKGROUND Traumatic injuries,such as falling,car accidents,and crushing mostly cause spinal fractures in young and middle-aged people,and>50%of them are thoracolumbar fractures.This kind of fracture is easily combined with serious injuries to peripheral nerves and soft tissues,which causes paralysis of the lower limbs if there is no timely rehabilitation treatment.Young patients with thoracolumbar fractures find it difficult to recover after the operation,and they are prone to depression,low self-esteem,and other negative emotions.AIM To investigate the association between anxiety,depression,and social stress in young patients with thoracolumbar spine fractures and the effect on rehabilitation outcomes.METHODS This study retrospectively analyzed 100 patients admitted to the orthopedic department of Honghui Hospital,Xi’an Jiaotong University who underwent thoracolumbar spine fracture surgery from January 2022 to June 2023.The general data of the patients were assessed with the Hamilton anxiety scale(HAMA),Hamilton depression scale(HAMD),life events scale,and social support rating scale(SSRS)to identify the correlation between anxiety,depression scores,and social stress and social support.The Japanese Orthopedic Association(JOA)was utilized to evaluate the rehabilitation outcomes of the patients and to analyze the effects of anxiety and depression scores on rehabilitation.RESULTS According to the scores of HAMD and HAMA in all patients,the prevalence of depression in patients was 39%(39/100),and the prevalence of anxiety was 49%(49/100).Patients were categorized into non-depression(n=61)and depression(n=39),non-anxiety(n=51),and anxiety(n=49)groups.Statistically significant differences in gender,occupation,Pittsburgh Sleep Quality Index(PSQI)score,and monthly family income were observed between the non-depression and depression groups(P<0.05).A significant difference in occupation and PSQI score was found between the non-anxiety and anxiety groups.Both depression(r=0.207,P=0.038)and anxiety scores(r=0.473,P<0.001)were significantly and positively correlated with negative life events.The difference in negative life event scores as well as SSRS total and item scores was statist-ically significant between patients in the non-depression and depression groups(P<0.05).The difference between the non-anxiety and anxiety groups was statistically significant(P<0.05)in the negative life event scores as well as the total SSRS scores.Additionally,JOA scores were significantly lower in both anxious and depressed patients.CONCLUSION Young patients with thoracolumbar fractures are prone to anxiety and depression.Patients’anxiety and depression are closely associated with social pressure,which reduces the life pressure of young patients with thoracolumbar fractures,enhances social support,and improves the psychology of anxiety and depression.,which affects patients’recovery.展开更多
The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained expe...The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.展开更多
Background of the Study: Femoral shaft fracture is the most common pediatric injury requiring hospitalization. For children less than 5 years old, non-surgical approach is recommended. For pediatric patients 5 - 14 ye...Background of the Study: Femoral shaft fracture is the most common pediatric injury requiring hospitalization. For children less than 5 years old, non-surgical approach is recommended. For pediatric patients 5 - 14 years old, the most common mode of treatment is flexible intramedullary nailing with a known complication of pain at post-op site, inflammatory reaction/bursitis at the entry site, superficial and deep infection, knee synovitis, knee stiffness, leg length discrepancy, proximal nail migration, angulation or malunion, delayed and non-union, implant breakage. This study aims to present a rare complication of a femoral fracture fixed with flexible intramedullary nail. Methodology: We report the outcome of a 12-year-old male with peri implant fracture of the left femur. He underwent removal of plates and screws and subsequently fixed with flexible intramedullary nails. Patient was followed up at 1, 3, 7, and 10 months post-operatively. Varus-valgus, sagittal angulation, and limb shortening were measured pre- and post-operatively. Complications were recorded on each visit. Results: Pre-operative varus angulation was 10˚, pro-curvatum of 55˚ with limb shortening of 4 cm. Postoperatively, varus was maintained to 10˚ but pro-curvatum was corrected to 4˚ and limb shortening was reduced to 1 cm. However, after 1 month the varus angulation increased to 30˚ while maintaining sagittal pro-curvatum. Limb shortening also increased to 2 cm. New bone formation started to appear along the mechanical axis of the left femur which is apparent at 3 months post-op and pro-curvatum increased to 20˚. At 7 and 10 months post-op no signs of union was noted at the fracture site but the callus formation along the mechanical axis gradually matured and appeared as a new femoral shaft. Conclusion: Formation of new bone in response to unstable flexible intramedullary fixation in pediatric femoral shaft fracture is a very rare complication.展开更多
Introduction: Open leg fracture is a diaphyseal or metaphyseal, extra-articular fracture of one or both leg bones, with communication between the fracture site and the external environment. To provide a broader contex...Introduction: Open leg fracture is a diaphyseal or metaphyseal, extra-articular fracture of one or both leg bones, with communication between the fracture site and the external environment. To provide a broader context, studies conducted globally have highlighted the significance of understanding open leg fractures due to their complex management and potential complications. Previous research in Africa and Europe provides comparative data that emphasizes regional differences in fracture types, causes, and treatment outcomes. This study aims to contribute to improving the management of theses fractures in Niger. Materials and Methods: This was a prospective, descriptive study carried out in the Traumatology-Orthopedics Department of the Zinder National Hospital, Niger, from December 8, 2020 to June 8, 2022 (18 months). We included all patients over 15 years of age in whom an open leg fracture was diagnosed and managed. Inclusion criteria focused on patients aged over 15 years with confirmed diagnoses of open leg fractures. Results: Over an 18-month period, the frequency of open leg fractures was 16.28%. There was a predominance of males (85.93% or n = 116). The average age of patients was 31.79 years. Road accidents were the primary circumstance of occurrence (93.33% or n = 126). The fracture line was simple in 74 patients (54.81%) and complex in 61 cases (45.19%). Surgically, the external fixator was used in 78 cases (57.80%). Postoperative follow-up was mostly straightforward. The main complications were infection (4 cases) and delayed consolidation (4 cases). Conclusion: Open leg fractures in adults are frequent at Zinder National Hospital. Public road accidents were the main cause of occurrence. An external fixator osteosynthesis was the most commonly used surgical option. These findings have important implications for healthcare policy, particularly in improving trauma care infrastructure and road safety initiatives in Niger. Future studies should prioritize the development of standardized treatment protocols and investigate the long-term outcomes of different surgical approaches.展开更多
This article focuses on the factors influencing fracture nonunion, classification and treatment. The article emphasizes the importance of understanding the influencing factors and mechanisms of fracture healing for de...This article focuses on the factors influencing fracture nonunion, classification and treatment. The article emphasizes the importance of understanding the influencing factors and mechanisms of fracture healing for developing effective treatment strategies and improving patients’ quality of life. It also points out the challenges of current treatment, such as patient compliance and limitations of treatment methods, and looks at future treatment directions.展开更多
Background and Objectives: The distal radius fracture (DRF) is a major public health problem in northern countries. Its frequency is constantly increasing. The locked anterior plate with its well-established biomechan...Background and Objectives: The distal radius fracture (DRF) is a major public health problem in northern countries. Its frequency is constantly increasing. The locked anterior plate with its well-established biomechanical properties, offers a reliable alternative. The aim of this study was to evaluate the radiological, the functional results and to determine the factors of poor postoperative prognosis of DRF treated with Newclip radial plates®. Methodology: This prospective cohort study evaluates the radiological and functional outcames of displaced radius fractures (DRFs) in patients ≥50 years old treated with Newclip® (locked anterior plates) at the Basse-Terre Hospital in Guadeloupe from 2022 to 2024. The patients were categorized into those with epiphyseal involvement (E1 - E4) and without epiphyseal involvement (E0) based on Laulan’s MEU classification. Radiological parameters (distal radio-ulnar index (DRUI), radial inclination frant view (IRF), radial inclination sagittal view (IRS) were assessed pre and post-operatively. Functional recovery was evaluated at 12 months using the QuickDash questionnaire. Results: Falls were the most common cause of fracture. Post-operatively, SRI was the least restored parameter. Poor prognostic factor for SRI improvement included posterior commimution and unstable fractures. Factors associated with higher QuickDash scores included unstable factures, unrestored DRUI, low plate position, metaphyseal features, and ulnar features. Conclusion: The anterior locking plate osteosynthesis is reliable treatment option with excellent functional outcomes.展开更多
Periprosthetic fracture of femur is a common and complex complication after joint replacement. With the increase of operation volume, its incidence is increasing year by year. The treatment of this fracture is affecte...Periprosthetic fracture of femur is a common and complex complication after joint replacement. With the increase of operation volume, its incidence is increasing year by year. The treatment of this fracture is affected by many factors, including fracture type, prosthesis stability, patient age and comorbidities, and individualized treatment strategy is needed. In recent years, the internal fixation technology and prosthetic revision technology have made significant progress in surgical treatment, such as locking steel plate, titanium cable and bridge combined internal fixation system and other new technologies have effectively improved the treatment effect. In addition, the application of new materials and 3D printing technology, as well as the optimization of multidisciplinary cooperation mode, also provide new ideas for the treatment of complex fractures. However, there are still some problems such as inaccurate diagnosis, difficult choice of treatment options and high incidence of postoperative complications. In the future, technological innovation, the introduction of artificial intelligence and big data, and the further development of personalized treatment will bring more possibilities to improve the prognosis and quality of life of patients. This study summarizes the relevant research results and prospects the future development direction, providing references for clinical practice and subsequent research.展开更多
BACKGROUND Fracture nonunion represents a challenging complication during fracture repair,often necessitating surgical intervention.Teriparatide,a recombinant human parathyroid hormone,has demonstrated promise in enha...BACKGROUND Fracture nonunion represents a challenging complication during fracture repair,often necessitating surgical intervention.Teriparatide,a recombinant human parathyroid hormone,has demonstrated promise in enhancing fracture healing,although its efficacy in treating established nonunion remains under investigation.CASE SUMMARY We report a case of a 27-year-old male who presented with a right humerus fracture following a traffic accident.Despite undergoing open reduction and internal fixation,the fracture resulted in a delayed union and subsequent nonunion.After 4 years of conservative management,teriparatide treatment was initiated due to persistent nonunion.Teriparatide injections were administered daily for 6 months,resulting in complete fracture healing and resolution of pain.CONCLUSION Our case demonstrates the successful use of teriparatide in treating a prolonged nonunion of a humerus fracture.Teriparatide may provide a valuable therapeutic option for established bone nonunion,even in cases that have not responded to conservative treatments.展开更多
BACKGROUND Extended care based on self-efficacy theory to elderly patients with intertrochanteric fractures will provide data reference to optimize the care plan of these patients,reduce patients’concurrent mental di...BACKGROUND Extended care based on self-efficacy theory to elderly patients with intertrochanteric fractures will provide data reference to optimize the care plan of these patients,reduce patients’concurrent mental diseases,and improve prognosis.AIM To analyze the value of extended nursing based on the self-efficacy theory in older patients with intertrochanteric fractures.METHODS Older patients with intertrochanteric fractures(n=88)admitted to our hospital between January 2021 and December 2024 were randomly divided into two groups-the control group(n=44,routine nursing)and the observation group(n=44,extended nursing)-via balloting and treated for 12 weeks.The mental state,pain severity,limb function,and self-nursing ability of all patients before and after nursing were analyzed.RESULTS After nursing,the Hamilton Anxiety Scale and General Self-Efficacy Scale scores of patients in the two groups improved.Notably,Hamilton Anxiety Scale and General Self-Efficacy Scale scores in the observation group were lower and higher,respectively,than those in the control group(P<0.05).The pain severity in the observation group(2.64±0.22)was lower than that in the control group(2.85±0.41)(P<0.05).The recovery rate of limb function was higher in the observation group than in the control group(P<0.05).In addition,the self-nursing ability scores of the patients in both groups increased,with a significantly higher score in the observation group(P<0.05).CONCLUSION Extended nursing based on the self-efficacy theory can significantly improve mental state,relieve pain,and promote the recovery of limb function and self-nursing ability in older patients with intertrochanteric fractures.展开更多
Loess-mudstone landslides are common in the Loess Plateau.Investigations into the mechanical theory of loess-mudstone landslides have become a challenging undertaking due to the distinctive interfacial properties of l...Loess-mudstone landslides are common in the Loess Plateau.Investigations into the mechanical theory of loess-mudstone landslides have become a challenging undertaking due to the distinctive interfacial properties of loess-mudstone and the unique water sensitivity characteristics of mudstone.Hence,it is imperative to develop innovative mechanical models and mathematical equations specifically tailored to loess-mudstone landslides.In this study,we analyze the fracture mechanism of the loess-mudstone sliding zone using plastic fracture mechanics and develop a unique fracture yield model.To calculate the energy release rate during the expansion of the loess-mudstone interface tip region,the shear fracture energy G is applied,which reflects both the yield failure criterion and the fracture failure criterion.To better understand the instability mechanism of loess-mudstone landslides,equilibrium equations based on G are established for tractive,compressive,and tensile loess-mudstone landslides.Based on the equilibrium equation,the critical length Lc of the sliding zone can be used for the safety evaluation of loess-mudstone landslides.In this way,this study proposes a new method for determining the failure mechanism and equilibrium equation of loessmudstone landslides,which resolves their starting mechanism,mechanical equilibrium equations,and safety evaluation indicators,thus justifying the scientific significance and practical value of this research.展开更多
Objective:To evaluate and analyze the actual efficacy of percutaneous vertebroplasty in the treatment of old unstable osteoporotic spinal fractures.Methods:From March 2023 to March 2024,46 patients with old unstable o...Objective:To evaluate and analyze the actual efficacy of percutaneous vertebroplasty in the treatment of old unstable osteoporotic spinal fractures.Methods:From March 2023 to March 2024,46 patients with old unstable osteoporotic spinal fractures in our hospital were included in this study.They were divided into the conventional group and the observation group based on treatment differences,with 23 patients in each group.The conventional group received conservative drug therapy,while the observation group underwent percutaneous vertebroplasty.The following indicators were compared and analyzed between the two groups:clinical treatment effect and improvement in physical function indicators.Results:The treatment efficiency of the observation group was 95.65%(22/23),while that of the conventional group was 69.57%(16/23).There was a significant difference between the groups,and the treatment effect of the observation group was significantly better(P<0.05).After treatment,the scores of physical status,daily living ability,functional independence,and life obstacles in the observation group were(89.33±4.08),(88.72±4.08),(90.41±2.89),(72.35±3.22),respectively,while those in the conventional group were(68.54±4.21),(67.42±4.11),(73.48±2.75),(72.35±3.22).There was a significant difference between the groups,and the improvement in physical function indicators in the observation group was more pronounced(P<0.05).Conclusion:For patients with old unstable osteoporotic spinal fractures,the basic value of percutaneous vertebroplasty is significant.It can not only improve clinical efficacy and safety but also promote the gradual recovery of patients'physical function indicators.It is recommended for clinical reference and practical application.展开更多
Objective:To observe and study the actual effects of percutaneous pedicle screw minimally invasive surgery in the treatment of spinal fractures and its impact on spinal function.Methods:This study included 48 patients...Objective:To observe and study the actual effects of percutaneous pedicle screw minimally invasive surgery in the treatment of spinal fractures and its impact on spinal function.Methods:This study included 48 patients with spinal fractures admitted between May 2023 and May 2024.The patients were divided into a control group and an experimental group based on treatment differences,with 24 patients in each group.The control group underwent open internal fixation surgery,while the experimental group received percutaneous pedicle screw minimally invasive surgery.Clinical index improvements,cervical dysfunction index,Japanese Orthopaedic Association scores,and pain level improvements were compared between the two groups.Results:The intraoperative blood loss,incision length,operation time,and hospitalization duration in the experimental group were(88.63±18.85),(6.32±1.05),(73.42±4.05),and(12.58±2.56),respectively,compared to(279.95±17.32),(12.89±1.36),(89.93±4.79),and(22.41±2.87)in the control group.Significant differences were observed between the groups,with the experimental group showing superior improvements across all metrics(P<0.05).Conclusion:Percutaneous pedicle screw minimally invasive surgery shows more significant effects in treating spinal fractures,particularly in improving cervical and lumbar spine function,enhancing treatment efficacy and safety,reducing pain levels,and shortening recovery time.Clinical application and promotion are recommended.展开更多
Objective: To analyze the therapeutic effect of combining dental arch splint intermaxillary traction with rigid internal fixation for the treatment of facial comminuted fractures. Methods: Sixty patients with facial c...Objective: To analyze the therapeutic effect of combining dental arch splint intermaxillary traction with rigid internal fixation for the treatment of facial comminuted fractures. Methods: Sixty patients with facial comminuted fractures admitted for treatment between July 2023 and December 2024 were selected. Using a random number table method, 30 patients were assigned to the observation group, where moderate traction using a dental arch splint combined with rigid internal fixation was applied. Another 30 patients were assigned to the control group and only received dental arch splint traction treatment. The total effective rate, postoperative recovery indicators, periodontal status, complication rate, and quality of life scores were compared between the two groups. Results: The total effective rate in the observation group was higher than that in the control group. The postoperative recovery indicators and periodontal status in the observation group were superior to those in the control group. The complication rate and quality of life score were lower in the observation group compared to the control group, with P < 0.05. Conclusion: Combining dental arch splint intermaxillary traction with rigid internal fixation can improve the periodontal status and quality of life of patients with facial comminuted fractures, shorten postoperative recovery time, reduce various complications, and enhance surgical efficacy.展开更多
To address the issue of extensive deformation in the Tabaiyi Tunnel caused by the fault zone,nuclear magnetic resonance(NMR)technology was employed to analyze the physical and mechanical properties of waterabsorbing m...To address the issue of extensive deformation in the Tabaiyi Tunnel caused by the fault zone,nuclear magnetic resonance(NMR)technology was employed to analyze the physical and mechanical properties of waterabsorbing mudstone.This analysis aimed to understand the mechanism behind the significant deformations.Drawing from the principle of excavation stress compensation,a support scheme featuring NPR anchorcables and an asymmetric truss support system was devised.To validate the scheme,numerical analysis using a combination of the Discrete Element Method(DEM)-Finite Element Method(FEM)was conducted.Additionally,similar material model tests and engineering measurements were carried out.Field experiments were also performed to evaluate the NPR anchor-cable and truss support system,focusing on anchor cable forces,pressures between the truss and surrounding rock,pressures between the initial support and secondary lining,as well as the magnitude of settlement and convergence deformation in the surrounding rock.The results indicate that the waterinduced expansion of clay minerals,resulting from damage caused by fissure water,accelerated the softening of the mudstone's internal structure,leading to significant deformations in the Tabaiyi Tunnel under high tectonic stress.The original support design fell short as the length of the anchor rods was smaller than the expansion depth of the plastic zone.As a result,the initial support structure bore the entire load from the surrounding rock,and a non-coupled deformation contact was observed between the double-arch truss and the surrounding rock.The adoption of NPR asymmetric anchor-cable support effectively restrained the expansion and asymmetric distribution characteristics of the plastic zone.Considering the mechanical degradation caused by water absorption in mudstone,the rigid constraint provided by the truss proved crucial for controlling the stability of the surrounding rock.These research findings hold significant implications for managing large deformations in soft rock tunnels situated within fractured zones under high tectonic stress conditions.展开更多
Objective:To evaluate the treatment effect of total hip arthroplasty(THA)for intertrochanteric femur fractures(IFF)in elderly patients.Methods:Thirty-two elderly patients with IFF admitted to the hospital from August ...Objective:To evaluate the treatment effect of total hip arthroplasty(THA)for intertrochanteric femur fractures(IFF)in elderly patients.Methods:Thirty-two elderly patients with IFF admitted to the hospital from August 2021 to August 2024 were selected and randomly divided into two groups using a random number table.The experimental group(16 patients)underwent THA surgery,while the control group(16 patients)underwent proximal femoral nail antirotation(PFNA)surgery.Hip joint function and quality of life indicators were compared between the two groups.Results:Before surgery,there was no significant difference in hip joint function and quality of life scores between the two groups(P>0.05).However,at six months postoperatively,the experimental group had higher hip joint function and quality of life scores compared to the control group(P<0.05).The total effective rate was higher in the experimental group than in the control group(P<0.05).The complication rate in the experimental group was similar to that in the control group(P>0.05).Conclusion:THA can improve the clinical efficacy of elderly patients with IFF,minimize postoperative complications,effectively restore hip joint function,and optimize postoperative quality of life.展开更多
Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fracture...Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fractured at 30° and 45° angles. The experimental results indicate that the steady creep strain rates of intact and fractured rock present an exponential increase trend with the increase of stress level. A nonlinear creep model is developed based on the experimental results, in which the initial damage caused by fracture together with the damage caused by constant load have been taken into consideration. The fitting analysis results indicated that the model proposed is more accurate at identifying the full creep regions in fractured granite, especially the accelerated stage of creep deformation. The least-square fit error of the proposed creep model is significantly lower than that of Nishihara model by almost an order of magnitude. An analysis of the effects of elastic modulus, viscosity coefficient, and damage factors on fractured rock strain rate and creep strain is conducted. If no consideration is given to the effects of the damage, the proposed nonlinear creep model can degenerate into to the classical Nishihara model.展开更多
Deep shale gas reservoirs have geological characteristics of high temperature,high pressure,high stress,and inferior ability to pass through fluids.The multi-stage fractured horizontal well is the key to exploiting th...Deep shale gas reservoirs have geological characteristics of high temperature,high pressure,high stress,and inferior ability to pass through fluids.The multi-stage fractured horizontal well is the key to exploiting the deep shale gas reservoir.However,during the production process,the effectiveness of the hydraulic fracture network decreases with the closure of fractures,which accelerates the decline of shale gas production.In this paper,we addressed the problems of unclear fracture closure mechanisms and low accuracy of shale gas production prediction during deep shale gas production.Then we established the fluid—solid—heat coupled model coupling the deformation and fluid flow among the fracture surface,proppant and the shale matrix.When the fluid—solid—heat coupled model was applied to the fracture network,it was well solved by our numerical method named discontinuous discrete fracture method.Compared with the conventional discrete fracture method,the discontinuous discrete fracture method can describe the three-dimensional morphology of the fracture while considering the effect of the change of fracture surface permeation coefficient on the coupled fracture—matrix flow and describing the displacement discontinuity across the fracture.Numerical simulations revealed that the degree of fracture closure increases as the production time proceeds,and the degree of closure of the secondary fractures is higher than that of the primary fractures.Shale creep and proppant embedment both increase the degree of fracture closure.The reduction in fracture surface permeability due to proppant embedment reduces the rate of fluid transfer between matrix and fracture,which has often been overlooked in the past.However,it significantly impacts shale gas production,with calculations showing a 24.7%cumulative three-year yield reduction.This study is helpful to understand the mechanism of hydraulic fracture closure.Therefore,it provides the theoretical guidance for maintaining the long-term effectiveness of hydraulic fractures.展开更多
基金Supported by 2021 Disciplinary Construction Project in School of Dentistry,Anhui Medical University,No.2021kqxkFY05.
文摘BACKGROUND Complicated crown–root fracture (CRF) involves severe injury to the crown, root,and pulp, and may be accompanied by multiple root fractures. The loss of a toothhas lifelong consequences for children and teenagers, but the maintenance of pulphealth and the calcific healing of multiple root fractures are rarely reported in theliterature.CASE SUMMARY This case reports healing of a permanent tooth with complicated crown–root andadditional root fractures, in which pulp health was maintained. A 10-year-old girlfell and fractured the root of her maxillary left central incisor at the cervical level.After the coronal fragment was repositioned, the tooth was splinted until thetooth was no longer mobile, 2 years later. Eight years after treatment, the toothhas remained asymptomatic with vital pulp and localized gingival overgrowth.Cone-beam computed tomography revealed not only calcified healing of the CRFbut also spontaneous healing in an additional undiagnosed root fracture. Thefracture line on the enamel could not be healed by hard tissue and formed agroove in the cervical crown. It was speculated that the groove was related to thelocalized gingival overgrowth.CONCLUSION This case provides a clinical perspective of the treatment of a tooth with acomplicated CRF and an additional root fracture.
基金funded by the project of the Major Scientific and Technological Projects of CNOOC in the 14th Five-Year Plan(No.KJGG2022-0701)the CNOOC Research Institute(No.2020PFS-03).
文摘To analyze the differences in the transport and distribution of different types of proppants and to address issues such as the short effective support of proppant and poor placement in hydraulically intersecting fractures,this study considered the combined impact of geological-engineering factors on conductivity.Using reservoir production parameters and the discrete elementmethod,multispherical proppants were constructed.Additionally,a 3D fracture model,based on the specified conditions of the L block,employed coupled(Computational Fluid Dynamics)CFD-DEM(Discrete ElementMethod)for joint simulations to quantitatively analyze the transport and placement patterns of multispherical proppants in intersecting fractures.Results indicate that turbulent kinetic energy is an intrinsic factor affecting proppant transport.Moreover,the efficiency of placement and migration distance of low-sphericity quartz sand constructed by the DEM in the main fracture are significantly reduced compared to spherical ceramic proppants,with a 27.7%decrease in the volume fraction of the fracture surface,subsequently affecting the placement concentration and damaging fracture conductivity.Compared to small-angle fractures,controlling artificial and natural fractures to expand at angles of 45°to 60°increases the effective support length by approximately 20.6%.During hydraulic fracturing of gas wells,ensuring the fracture support area and post-closure conductivity can be achieved by controlling the sphericity of proppants and adjusting the perforation direction to control the direction of artificial fractures.
文摘BACKGROUND Traumatic injuries,such as falling,car accidents,and crushing mostly cause spinal fractures in young and middle-aged people,and>50%of them are thoracolumbar fractures.This kind of fracture is easily combined with serious injuries to peripheral nerves and soft tissues,which causes paralysis of the lower limbs if there is no timely rehabilitation treatment.Young patients with thoracolumbar fractures find it difficult to recover after the operation,and they are prone to depression,low self-esteem,and other negative emotions.AIM To investigate the association between anxiety,depression,and social stress in young patients with thoracolumbar spine fractures and the effect on rehabilitation outcomes.METHODS This study retrospectively analyzed 100 patients admitted to the orthopedic department of Honghui Hospital,Xi’an Jiaotong University who underwent thoracolumbar spine fracture surgery from January 2022 to June 2023.The general data of the patients were assessed with the Hamilton anxiety scale(HAMA),Hamilton depression scale(HAMD),life events scale,and social support rating scale(SSRS)to identify the correlation between anxiety,depression scores,and social stress and social support.The Japanese Orthopedic Association(JOA)was utilized to evaluate the rehabilitation outcomes of the patients and to analyze the effects of anxiety and depression scores on rehabilitation.RESULTS According to the scores of HAMD and HAMA in all patients,the prevalence of depression in patients was 39%(39/100),and the prevalence of anxiety was 49%(49/100).Patients were categorized into non-depression(n=61)and depression(n=39),non-anxiety(n=51),and anxiety(n=49)groups.Statistically significant differences in gender,occupation,Pittsburgh Sleep Quality Index(PSQI)score,and monthly family income were observed between the non-depression and depression groups(P<0.05).A significant difference in occupation and PSQI score was found between the non-anxiety and anxiety groups.Both depression(r=0.207,P=0.038)and anxiety scores(r=0.473,P<0.001)were significantly and positively correlated with negative life events.The difference in negative life event scores as well as SSRS total and item scores was statist-ically significant between patients in the non-depression and depression groups(P<0.05).The difference between the non-anxiety and anxiety groups was statistically significant(P<0.05)in the negative life event scores as well as the total SSRS scores.Additionally,JOA scores were significantly lower in both anxious and depressed patients.CONCLUSION Young patients with thoracolumbar fractures are prone to anxiety and depression.Patients’anxiety and depression are closely associated with social pressure,which reduces the life pressure of young patients with thoracolumbar fractures,enhances social support,and improves the psychology of anxiety and depression.,which affects patients’recovery.
文摘The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.
文摘Background of the Study: Femoral shaft fracture is the most common pediatric injury requiring hospitalization. For children less than 5 years old, non-surgical approach is recommended. For pediatric patients 5 - 14 years old, the most common mode of treatment is flexible intramedullary nailing with a known complication of pain at post-op site, inflammatory reaction/bursitis at the entry site, superficial and deep infection, knee synovitis, knee stiffness, leg length discrepancy, proximal nail migration, angulation or malunion, delayed and non-union, implant breakage. This study aims to present a rare complication of a femoral fracture fixed with flexible intramedullary nail. Methodology: We report the outcome of a 12-year-old male with peri implant fracture of the left femur. He underwent removal of plates and screws and subsequently fixed with flexible intramedullary nails. Patient was followed up at 1, 3, 7, and 10 months post-operatively. Varus-valgus, sagittal angulation, and limb shortening were measured pre- and post-operatively. Complications were recorded on each visit. Results: Pre-operative varus angulation was 10˚, pro-curvatum of 55˚ with limb shortening of 4 cm. Postoperatively, varus was maintained to 10˚ but pro-curvatum was corrected to 4˚ and limb shortening was reduced to 1 cm. However, after 1 month the varus angulation increased to 30˚ while maintaining sagittal pro-curvatum. Limb shortening also increased to 2 cm. New bone formation started to appear along the mechanical axis of the left femur which is apparent at 3 months post-op and pro-curvatum increased to 20˚. At 7 and 10 months post-op no signs of union was noted at the fracture site but the callus formation along the mechanical axis gradually matured and appeared as a new femoral shaft. Conclusion: Formation of new bone in response to unstable flexible intramedullary fixation in pediatric femoral shaft fracture is a very rare complication.
文摘Introduction: Open leg fracture is a diaphyseal or metaphyseal, extra-articular fracture of one or both leg bones, with communication between the fracture site and the external environment. To provide a broader context, studies conducted globally have highlighted the significance of understanding open leg fractures due to their complex management and potential complications. Previous research in Africa and Europe provides comparative data that emphasizes regional differences in fracture types, causes, and treatment outcomes. This study aims to contribute to improving the management of theses fractures in Niger. Materials and Methods: This was a prospective, descriptive study carried out in the Traumatology-Orthopedics Department of the Zinder National Hospital, Niger, from December 8, 2020 to June 8, 2022 (18 months). We included all patients over 15 years of age in whom an open leg fracture was diagnosed and managed. Inclusion criteria focused on patients aged over 15 years with confirmed diagnoses of open leg fractures. Results: Over an 18-month period, the frequency of open leg fractures was 16.28%. There was a predominance of males (85.93% or n = 116). The average age of patients was 31.79 years. Road accidents were the primary circumstance of occurrence (93.33% or n = 126). The fracture line was simple in 74 patients (54.81%) and complex in 61 cases (45.19%). Surgically, the external fixator was used in 78 cases (57.80%). Postoperative follow-up was mostly straightforward. The main complications were infection (4 cases) and delayed consolidation (4 cases). Conclusion: Open leg fractures in adults are frequent at Zinder National Hospital. Public road accidents were the main cause of occurrence. An external fixator osteosynthesis was the most commonly used surgical option. These findings have important implications for healthcare policy, particularly in improving trauma care infrastructure and road safety initiatives in Niger. Future studies should prioritize the development of standardized treatment protocols and investigate the long-term outcomes of different surgical approaches.
文摘This article focuses on the factors influencing fracture nonunion, classification and treatment. The article emphasizes the importance of understanding the influencing factors and mechanisms of fracture healing for developing effective treatment strategies and improving patients’ quality of life. It also points out the challenges of current treatment, such as patient compliance and limitations of treatment methods, and looks at future treatment directions.
文摘Background and Objectives: The distal radius fracture (DRF) is a major public health problem in northern countries. Its frequency is constantly increasing. The locked anterior plate with its well-established biomechanical properties, offers a reliable alternative. The aim of this study was to evaluate the radiological, the functional results and to determine the factors of poor postoperative prognosis of DRF treated with Newclip radial plates®. Methodology: This prospective cohort study evaluates the radiological and functional outcames of displaced radius fractures (DRFs) in patients ≥50 years old treated with Newclip® (locked anterior plates) at the Basse-Terre Hospital in Guadeloupe from 2022 to 2024. The patients were categorized into those with epiphyseal involvement (E1 - E4) and without epiphyseal involvement (E0) based on Laulan’s MEU classification. Radiological parameters (distal radio-ulnar index (DRUI), radial inclination frant view (IRF), radial inclination sagittal view (IRS) were assessed pre and post-operatively. Functional recovery was evaluated at 12 months using the QuickDash questionnaire. Results: Falls were the most common cause of fracture. Post-operatively, SRI was the least restored parameter. Poor prognostic factor for SRI improvement included posterior commimution and unstable fractures. Factors associated with higher QuickDash scores included unstable factures, unrestored DRUI, low plate position, metaphyseal features, and ulnar features. Conclusion: The anterior locking plate osteosynthesis is reliable treatment option with excellent functional outcomes.
文摘Periprosthetic fracture of femur is a common and complex complication after joint replacement. With the increase of operation volume, its incidence is increasing year by year. The treatment of this fracture is affected by many factors, including fracture type, prosthesis stability, patient age and comorbidities, and individualized treatment strategy is needed. In recent years, the internal fixation technology and prosthetic revision technology have made significant progress in surgical treatment, such as locking steel plate, titanium cable and bridge combined internal fixation system and other new technologies have effectively improved the treatment effect. In addition, the application of new materials and 3D printing technology, as well as the optimization of multidisciplinary cooperation mode, also provide new ideas for the treatment of complex fractures. However, there are still some problems such as inaccurate diagnosis, difficult choice of treatment options and high incidence of postoperative complications. In the future, technological innovation, the introduction of artificial intelligence and big data, and the further development of personalized treatment will bring more possibilities to improve the prognosis and quality of life of patients. This study summarizes the relevant research results and prospects the future development direction, providing references for clinical practice and subsequent research.
基金Supported by National Natural Science Foundation of China,No.82172441Suzhou City Major Disease Multicenter Clinical Research Project,No.DZXYJ202312+2 种基金Special Funding for Jiangsu Province Science and Technology Plan(Key Research and Development Program for Social Development),No.BE2023737Gusu Health Talent Plan Scientific Research Project,No.GSWS2022109Postgraduate Research and Practice Innovation Program of Jiangsu Province,No.SJCX24_2446.
文摘BACKGROUND Fracture nonunion represents a challenging complication during fracture repair,often necessitating surgical intervention.Teriparatide,a recombinant human parathyroid hormone,has demonstrated promise in enhancing fracture healing,although its efficacy in treating established nonunion remains under investigation.CASE SUMMARY We report a case of a 27-year-old male who presented with a right humerus fracture following a traffic accident.Despite undergoing open reduction and internal fixation,the fracture resulted in a delayed union and subsequent nonunion.After 4 years of conservative management,teriparatide treatment was initiated due to persistent nonunion.Teriparatide injections were administered daily for 6 months,resulting in complete fracture healing and resolution of pain.CONCLUSION Our case demonstrates the successful use of teriparatide in treating a prolonged nonunion of a humerus fracture.Teriparatide may provide a valuable therapeutic option for established bone nonunion,even in cases that have not responded to conservative treatments.
文摘BACKGROUND Extended care based on self-efficacy theory to elderly patients with intertrochanteric fractures will provide data reference to optimize the care plan of these patients,reduce patients’concurrent mental diseases,and improve prognosis.AIM To analyze the value of extended nursing based on the self-efficacy theory in older patients with intertrochanteric fractures.METHODS Older patients with intertrochanteric fractures(n=88)admitted to our hospital between January 2021 and December 2024 were randomly divided into two groups-the control group(n=44,routine nursing)and the observation group(n=44,extended nursing)-via balloting and treated for 12 weeks.The mental state,pain severity,limb function,and self-nursing ability of all patients before and after nursing were analyzed.RESULTS After nursing,the Hamilton Anxiety Scale and General Self-Efficacy Scale scores of patients in the two groups improved.Notably,Hamilton Anxiety Scale and General Self-Efficacy Scale scores in the observation group were lower and higher,respectively,than those in the control group(P<0.05).The pain severity in the observation group(2.64±0.22)was lower than that in the control group(2.85±0.41)(P<0.05).The recovery rate of limb function was higher in the observation group than in the control group(P<0.05).In addition,the self-nursing ability scores of the patients in both groups increased,with a significantly higher score in the observation group(P<0.05).CONCLUSION Extended nursing based on the self-efficacy theory can significantly improve mental state,relieve pain,and promote the recovery of limb function and self-nursing ability in older patients with intertrochanteric fractures.
基金supported by The National Natural Science Foundation of China(Grant No.12362034)The Scientific Research Project of Inner Mongolia University of Technology(Grant Nos.DC2200000913+1 种基金DC2300001439)The Science and Technology Plan Project of Inner Mongolia Autonomous Region(Grant No.2022YFSH0047)。
文摘Loess-mudstone landslides are common in the Loess Plateau.Investigations into the mechanical theory of loess-mudstone landslides have become a challenging undertaking due to the distinctive interfacial properties of loess-mudstone and the unique water sensitivity characteristics of mudstone.Hence,it is imperative to develop innovative mechanical models and mathematical equations specifically tailored to loess-mudstone landslides.In this study,we analyze the fracture mechanism of the loess-mudstone sliding zone using plastic fracture mechanics and develop a unique fracture yield model.To calculate the energy release rate during the expansion of the loess-mudstone interface tip region,the shear fracture energy G is applied,which reflects both the yield failure criterion and the fracture failure criterion.To better understand the instability mechanism of loess-mudstone landslides,equilibrium equations based on G are established for tractive,compressive,and tensile loess-mudstone landslides.Based on the equilibrium equation,the critical length Lc of the sliding zone can be used for the safety evaluation of loess-mudstone landslides.In this way,this study proposes a new method for determining the failure mechanism and equilibrium equation of loessmudstone landslides,which resolves their starting mechanism,mechanical equilibrium equations,and safety evaluation indicators,thus justifying the scientific significance and practical value of this research.
文摘Objective:To evaluate and analyze the actual efficacy of percutaneous vertebroplasty in the treatment of old unstable osteoporotic spinal fractures.Methods:From March 2023 to March 2024,46 patients with old unstable osteoporotic spinal fractures in our hospital were included in this study.They were divided into the conventional group and the observation group based on treatment differences,with 23 patients in each group.The conventional group received conservative drug therapy,while the observation group underwent percutaneous vertebroplasty.The following indicators were compared and analyzed between the two groups:clinical treatment effect and improvement in physical function indicators.Results:The treatment efficiency of the observation group was 95.65%(22/23),while that of the conventional group was 69.57%(16/23).There was a significant difference between the groups,and the treatment effect of the observation group was significantly better(P<0.05).After treatment,the scores of physical status,daily living ability,functional independence,and life obstacles in the observation group were(89.33±4.08),(88.72±4.08),(90.41±2.89),(72.35±3.22),respectively,while those in the conventional group were(68.54±4.21),(67.42±4.11),(73.48±2.75),(72.35±3.22).There was a significant difference between the groups,and the improvement in physical function indicators in the observation group was more pronounced(P<0.05).Conclusion:For patients with old unstable osteoporotic spinal fractures,the basic value of percutaneous vertebroplasty is significant.It can not only improve clinical efficacy and safety but also promote the gradual recovery of patients'physical function indicators.It is recommended for clinical reference and practical application.
文摘Objective:To observe and study the actual effects of percutaneous pedicle screw minimally invasive surgery in the treatment of spinal fractures and its impact on spinal function.Methods:This study included 48 patients with spinal fractures admitted between May 2023 and May 2024.The patients were divided into a control group and an experimental group based on treatment differences,with 24 patients in each group.The control group underwent open internal fixation surgery,while the experimental group received percutaneous pedicle screw minimally invasive surgery.Clinical index improvements,cervical dysfunction index,Japanese Orthopaedic Association scores,and pain level improvements were compared between the two groups.Results:The intraoperative blood loss,incision length,operation time,and hospitalization duration in the experimental group were(88.63±18.85),(6.32±1.05),(73.42±4.05),and(12.58±2.56),respectively,compared to(279.95±17.32),(12.89±1.36),(89.93±4.79),and(22.41±2.87)in the control group.Significant differences were observed between the groups,with the experimental group showing superior improvements across all metrics(P<0.05).Conclusion:Percutaneous pedicle screw minimally invasive surgery shows more significant effects in treating spinal fractures,particularly in improving cervical and lumbar spine function,enhancing treatment efficacy and safety,reducing pain levels,and shortening recovery time.Clinical application and promotion are recommended.
基金Special Support Program for Scientific and Technological Talent“Application and Impact of Dental Arch Splint Intermaxillary Traction Combined with Rigid Internal Fixation on Oral Health in Patients with Facial Fractures”(DX2023BR18)。
文摘Objective: To analyze the therapeutic effect of combining dental arch splint intermaxillary traction with rigid internal fixation for the treatment of facial comminuted fractures. Methods: Sixty patients with facial comminuted fractures admitted for treatment between July 2023 and December 2024 were selected. Using a random number table method, 30 patients were assigned to the observation group, where moderate traction using a dental arch splint combined with rigid internal fixation was applied. Another 30 patients were assigned to the control group and only received dental arch splint traction treatment. The total effective rate, postoperative recovery indicators, periodontal status, complication rate, and quality of life scores were compared between the two groups. Results: The total effective rate in the observation group was higher than that in the control group. The postoperative recovery indicators and periodontal status in the observation group were superior to those in the control group. The complication rate and quality of life score were lower in the observation group compared to the control group, with P < 0.05. Conclusion: Combining dental arch splint intermaxillary traction with rigid internal fixation can improve the periodontal status and quality of life of patients with facial comminuted fractures, shorten postoperative recovery time, reduce various complications, and enhance surgical efficacy.
基金financially supported by the Innovation Fund Research Project of State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology(Grant No.SKLGDUEK202201)。
文摘To address the issue of extensive deformation in the Tabaiyi Tunnel caused by the fault zone,nuclear magnetic resonance(NMR)technology was employed to analyze the physical and mechanical properties of waterabsorbing mudstone.This analysis aimed to understand the mechanism behind the significant deformations.Drawing from the principle of excavation stress compensation,a support scheme featuring NPR anchorcables and an asymmetric truss support system was devised.To validate the scheme,numerical analysis using a combination of the Discrete Element Method(DEM)-Finite Element Method(FEM)was conducted.Additionally,similar material model tests and engineering measurements were carried out.Field experiments were also performed to evaluate the NPR anchor-cable and truss support system,focusing on anchor cable forces,pressures between the truss and surrounding rock,pressures between the initial support and secondary lining,as well as the magnitude of settlement and convergence deformation in the surrounding rock.The results indicate that the waterinduced expansion of clay minerals,resulting from damage caused by fissure water,accelerated the softening of the mudstone's internal structure,leading to significant deformations in the Tabaiyi Tunnel under high tectonic stress.The original support design fell short as the length of the anchor rods was smaller than the expansion depth of the plastic zone.As a result,the initial support structure bore the entire load from the surrounding rock,and a non-coupled deformation contact was observed between the double-arch truss and the surrounding rock.The adoption of NPR asymmetric anchor-cable support effectively restrained the expansion and asymmetric distribution characteristics of the plastic zone.Considering the mechanical degradation caused by water absorption in mudstone,the rigid constraint provided by the truss proved crucial for controlling the stability of the surrounding rock.These research findings hold significant implications for managing large deformations in soft rock tunnels situated within fractured zones under high tectonic stress conditions.
文摘Objective:To evaluate the treatment effect of total hip arthroplasty(THA)for intertrochanteric femur fractures(IFF)in elderly patients.Methods:Thirty-two elderly patients with IFF admitted to the hospital from August 2021 to August 2024 were selected and randomly divided into two groups using a random number table.The experimental group(16 patients)underwent THA surgery,while the control group(16 patients)underwent proximal femoral nail antirotation(PFNA)surgery.Hip joint function and quality of life indicators were compared between the two groups.Results:Before surgery,there was no significant difference in hip joint function and quality of life scores between the two groups(P>0.05).However,at six months postoperatively,the experimental group had higher hip joint function and quality of life scores compared to the control group(P<0.05).The total effective rate was higher in the experimental group than in the control group(P<0.05).The complication rate in the experimental group was similar to that in the control group(P>0.05).Conclusion:THA can improve the clinical efficacy of elderly patients with IFF,minimize postoperative complications,effectively restore hip joint function,and optimize postoperative quality of life.
基金supported by the National Natural Science Foundation of China(No.42307258)the technological research projects in Sichuan Province(No.2022YFSY0007)the China Atomic Energy Authority(CAEA)through the Geological Disposal Program.
文摘Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fractured at 30° and 45° angles. The experimental results indicate that the steady creep strain rates of intact and fractured rock present an exponential increase trend with the increase of stress level. A nonlinear creep model is developed based on the experimental results, in which the initial damage caused by fracture together with the damage caused by constant load have been taken into consideration. The fitting analysis results indicated that the model proposed is more accurate at identifying the full creep regions in fractured granite, especially the accelerated stage of creep deformation. The least-square fit error of the proposed creep model is significantly lower than that of Nishihara model by almost an order of magnitude. An analysis of the effects of elastic modulus, viscosity coefficient, and damage factors on fractured rock strain rate and creep strain is conducted. If no consideration is given to the effects of the damage, the proposed nonlinear creep model can degenerate into to the classical Nishihara model.
基金the supports provided by China University of Petroleum,Beijing(Grand No.ZX20230042)the National Natural Science Foundation of China(Grand No.52334001and Grand No.51904314)。
文摘Deep shale gas reservoirs have geological characteristics of high temperature,high pressure,high stress,and inferior ability to pass through fluids.The multi-stage fractured horizontal well is the key to exploiting the deep shale gas reservoir.However,during the production process,the effectiveness of the hydraulic fracture network decreases with the closure of fractures,which accelerates the decline of shale gas production.In this paper,we addressed the problems of unclear fracture closure mechanisms and low accuracy of shale gas production prediction during deep shale gas production.Then we established the fluid—solid—heat coupled model coupling the deformation and fluid flow among the fracture surface,proppant and the shale matrix.When the fluid—solid—heat coupled model was applied to the fracture network,it was well solved by our numerical method named discontinuous discrete fracture method.Compared with the conventional discrete fracture method,the discontinuous discrete fracture method can describe the three-dimensional morphology of the fracture while considering the effect of the change of fracture surface permeation coefficient on the coupled fracture—matrix flow and describing the displacement discontinuity across the fracture.Numerical simulations revealed that the degree of fracture closure increases as the production time proceeds,and the degree of closure of the secondary fractures is higher than that of the primary fractures.Shale creep and proppant embedment both increase the degree of fracture closure.The reduction in fracture surface permeability due to proppant embedment reduces the rate of fluid transfer between matrix and fracture,which has often been overlooked in the past.However,it significantly impacts shale gas production,with calculations showing a 24.7%cumulative three-year yield reduction.This study is helpful to understand the mechanism of hydraulic fracture closure.Therefore,it provides the theoretical guidance for maintaining the long-term effectiveness of hydraulic fractures.
