BACKGROUND Motorcycle accidents often result in abdominal trauma in patients seeking emergency care.Injuries to the hollow viscera,including the duodenum,jejunum,urinary bladder,and colorectum,are relatively common.In...BACKGROUND Motorcycle accidents often result in abdominal trauma in patients seeking emergency care.Injuries to the hollow viscera,including the duodenum,jejunum,urinary bladder,and colorectum,are relatively common.In contrast,owing to the protective function of the anterior rib cage,gastric rupture is exceptionally rare,with an incidence of<1.7%.Gastric rupture typically occurs in the anterior wall and rarely presents as multiple ruptures.This report describes an unusual case of multiple gastric ruptures resulting from blunt trauma.CASE SUMMARY A 21-year-old man,who was involved in a motorcycle collision at 70 km/hour after consuming a large meal,presented with hypotension.Physical examination revealed abdominal tenderness.Laboratory test results indicated elevated amylase,lipase,and liver enzyme levels.Computed tomography showed pneumoperitoneum,hemoperitoneum,and gastric wall discontinuation,suggesting gastric perforation alongside pancreatic,splenic,and hepatic injuries.Angiographic embolization was performed because of active contrast leakage in the left gastric and right gastroepiploic arteries.Emergency laparotomy revealed substantial blood loss,hematoma,and gastric contents scattered throughout the abdominal cavity.Two 10 cm gastric perforations in the anterior and posterior walls were identified,as well as severe liver damage,splenic injury,and pancreatic contusion.Surgical interventions included primary closure of the gastric wall,splenectomy,and partial hepatectomy.After temporary abdominal closure,the patient underwent a second surgery without further bleeding.The gastric repair site was resected and reinforced for optimal tissue healing.CONCLUSION Gastric rupture following blunt trauma is fatal.However,patients without severe complications can recover through surgical interventions and postoperative care.展开更多
Colonoscopy represents a safe procedure that is widely used in medical practice either to diagnose or treat various gastrointestinal diseases.During the last few years,the incidence rate of perforations in colonoscopi...Colonoscopy represents a safe procedure that is widely used in medical practice either to diagnose or treat various gastrointestinal diseases.During the last few years,the incidence rate of perforations in colonoscopic procedures has increased,especially in therapeutic colonoscopies.The recent advancements in endoscopic techniques and gastrointestinal tumoral resection procedures such as endoscopic mucosal resection,endoscopic full-thickness resection,and endoscopic submucosal dissection(ESD)could be a risk factor for this increased risk.The incidence rate of mortality of serious colonoscopic perforations is 7.1%.The management plan for these perforations starts with conservative treatment in mild cases,endoscopic closure,and surgical management in severe cases.Recently,endoluminal vacuum therapy was found to be effective in the management of colorectal perforations and this has been reported in multiple case reports.This editorial provides an overview of the current guidelines for the management of iatrogenic colorectal perforations.These insights are from the perspectives of endoscopists and gastroenterologists.We also present a management algorithm based on the guidelines of the European Society of Gastrointestinal Endoscopy,the American Gastroenterological Association,and the World Society of Emergency Surgery.We also discussed in brief the use of endoluminal vacuum therapy in colorectal perforations.展开更多
A theoretical analysis on the perforation of Weldox 460E steel plates struck by flat-nosed projectiles is presented using a previously developed model within a unified framework.This model contains a dimensionless emp...A theoretical analysis on the perforation of Weldox 460E steel plates struck by flat-nosed projectiles is presented using a previously developed model within a unified framework.This model contains a dimensionless empirical equation to describe the variation of energy absorbed through global deformation as a function of impact velocity.The study further investigates the energy absorption mechanisms of Weldox 460E steel plates,with particular focus on the“plateau”phenomenon,i.e.,limited increase in ballistic limit with increasing plate thickness.This phenomenon is explained and compared with results from previously studied 2024-T351 aluminium plates.The model predictions agree well with experimental data for Weldox 460E steel plates impacted by flat-nosed projectiles,including:relationship between global deformation and impact velocity,ballistic limit,residual velocity,and critical conditions for the transition of failure modes.Moreover,the model effectively predicts the“plateau”phenomenon observed in intermediate plate thickness range.It is also found that the indentation absorption energy contributes a significantly larger fraction of the total absorption energy in Weldox 460E steel plates perforated by flat-nosed projectiles than in 2024-T351 aluminium plates,due to the differences in material properties.展开更多
BACKGROUND Intestinal obstruction(IO)in pregnancy,though rare(1:1500-1:66000),carries high maternal(6%-10%)and fetal mortality(26%).Adhesions from prior surgery are the leading cause.Diagnosis is often delayed due to ...BACKGROUND Intestinal obstruction(IO)in pregnancy,though rare(1:1500-1:66000),carries high maternal(6%-10%)and fetal mortality(26%).Adhesions from prior surgery are the leading cause.Diagnosis is often delayed due to symptom overlap with nor-mal pregnancy,increasing risks of perforation and sepsis.CASE SUMMARY A 25-year-old gravida 2 para 1 woman at 28 weeks of gestation presented with 1-week constipation,feculent vomiting,and abdominal distension.She had a history of exploratory laparotomy in 2015 for blunt abdominal trauma.The diagnosis of IO in pregnancy was confirmed via abdominopelvic ultrasound and clinical findings.Interventions included conservative measures(nasogastric tube decompression,enemas)followed by emergency laparotomy with bowel resec-tion/anastomosis.Despite surgical management,the patient succumbed to septic shock.CONCLUSION High clinical suspicion,expedited cross-sectional imaging(computed tomogra-phy/Magnetic resonance imaging),and emergent surgery are critical to reduce mortality.展开更多
It has been experimentally observed that,in the perforation of metal plates by a flat-nosed projectile,there exists a plateau phenomenon where the ballistic limit increases slightly with increasing plate thickness,whi...It has been experimentally observed that,in the perforation of metal plates by a flat-nosed projectile,there exists a plateau phenomenon where the ballistic limit increases slightly with increasing plate thickness,which is related to a change in the mode of failure.No theoretical model has so far explained this phenomenon satisfactorily.This paper presents a combined numerical and theoretical study on the perforation of 2024-T351 aluminum plates struck by flat-nosed projectiles.First,numerical simulations are performed to investigate the failure mechanisms/deformation modes of the aluminum plates.Then,a theoretical model is proposed based on the numerical results and the experimental observations within a unified framework.The model takes into account the main energy absorbing mechanisms and the corresponding energies absorbed are determined analytically.In particular,a dimensionless equation is suggested to describe the relationship between global deformations and impact velocity.It transpires that the model predictions are in good agreement with the test data and the numerical results for the perforation of 2024-T351 aluminum plates struck by rigid flat-nosed projectiles in terms of residual velocity,ballistic limit,relationship between global deformations and impact velocity,and transition of failure modes.It also transpires that the present model can predict the“plateau”phenomenon,which shows a slight increase in ballistic limit as plate thickness increases.Furthermore,the energy absorption mechanisms are discussed on the basis of the theoretical analysis.展开更多
Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the ...Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the low-permeability characteristics with an average permeability of 5.5 mD and moderate heterogeneity,a 3-D geological model of heterogeneous Class I hydrate reservoirs with three-phase transition layers is established by Kriging interpolation and stochastic modeling method,and a numerical simulation model is used to describe the depressurization production performance of the reservoir.With the development of depressurization,a specific range of complete decomposition zones appear both in the hydrate and transition layers.The entire decomposition zone of the whole reservoir tends to outward and upward diffusion.There is apparent methane escape in the three-phase transition layer.Due to the improvement of local permeability caused by the phase transition of hydrate dissociation,some methane accumulation occurs at the bottom of the hydrate layer,forming a local methane enrichment zone.The methane migration trends in reservoirs are mainly characterized by movement toward production wells and hydrate layers under the influence of gravity.However,due to the permeability limitation of hydrate reservoirs,many fluids have not been effectively produced and remain in the reservoir.Therefore,to improve the effective pressure drop of the reservoir,the perforation method and pressure reduction method were optimized by analyzing the influencing factors based on the gas production rate.The comparative study demonstrates that perforating through the free gas layer combined with one-time depressurization can enhance the effective depressurization and improve production performance.The gas production rate from perforating through the free gas layer can be twice as high as that from perforating through the transition layer.This study can provide theoretical support for the utilization of marine energy.展开更多
Several issues should be considered before the surgical treatment of gastric ulcer perforations,including morbidity,mortality,and recurrence.However,an oftenoverlooked issue is determining the cause of the perforation...Several issues should be considered before the surgical treatment of gastric ulcer perforations,including morbidity,mortality,and recurrence.However,an oftenoverlooked issue is determining the cause of the perforation.When the perforation is secondary to an underlying and undiagnosed malignancy,stomach resection inadequately treats the oncological disease and may increase postoperative morbidity and require re-surgery.展开更多
BACKGROUND Acute abdominal pain is one of the most common gastrointestinal symptoms.The etiology of acute abdomen can be challenging for gastroenterologists to establish.Cecal foreign body is a rare cause of cecal per...BACKGROUND Acute abdominal pain is one of the most common gastrointestinal symptoms.The etiology of acute abdomen can be challenging for gastroenterologists to establish.Cecal foreign body is a rare cause of cecal perforation.CASE SUMMARY We report a 35-year-old male from China who initially exhibited symptoms suggestive of acute appendicitis.However,during a minimally invasive colonoscopy procedure,the authors found that a wooden toothpick caused the perforation.The patient presented to our emergency department with a 2 days history of right lower abdominal pain and low grade fever.The patient was in good health and had eaten fish 2 days earlier.Physical examination revealed mild pain with positive rebound tenderness in the right lower abdomen.However,computed tomography of the abdomen confirmed a strip of high-density shadows protruding beyond the intestinal cavity outline,with a small amount of peritoneal seepage in the ileocecal area.Combined with the medical history,the possibility of foreign body perforation by a fishbone and peripheral peritonitis were considered.However,the high-density shadow was identified as a wooden toothpick,which was removed via a minimally invasive procedure using a foreign body forceps under colonoscopy.The patient's condition improved significantly within 5 days after treatment.CONCLUSION We emphasize the importance of a detailed patient history,accurate diagnosis and proper treatment in patients with acute abdomen.展开更多
Based on the Low Frequency Distributed Acoustic Sensing(LF-DAS)fiber optic monitoring and downhole hawk-eye imaging,the fluid and sand distribution and perforation erosion of all clusters during hydraulic fracturing w...Based on the Low Frequency Distributed Acoustic Sensing(LF-DAS)fiber optic monitoring and downhole hawk-eye imaging,the fluid and sand distribution and perforation erosion of all clusters during hydraulic fracturing were evaluated,and then a fully coupled wellbore-perforation-fracture numerical model was established to simulate the whole process of sand-carrying fluid migration and analyze key influencing factors.The proppant and fracturing fluid exhibit divergent flow pathways during multi-staged,multi-cluster fracturing in horizontal wells,resulting in significant heterogeneity in the fluid-proppant distribution among clusters.Perforation erosion is prevalent,and perforation erosion and sand inflow ratio have phase bias.The trajectory of proppant transport is controlled by the combined effects of inertia of particle migration and gravity settlement.The inertial effect is dominant at the wellbore heel,where the fluid flow rate is high,hindering particles turning into perforations and causing uneven sand distribution among clusters.The gravity settlement is more pronounced toward the wellbore toe,where the fluid flow rate is low,leading to enhanced phase-bias of slurry distribution and perforation erosion.Increasing the pumping rate reduces the influence of gravity settlement,mitigating the phase bias of sand inflow and perforation erosion.However,the large pumping rate limits the sand inflow efficiency near the heel clusters,and more proppants accumulate towards the toe clusters.High-viscosity fluids improve particle suspension,achieving more uniform proppant placement within wellbore and fractures.Larger particle sizes exacerbate sand inflow differences among clusters and perforations,limiting the proppant placement range within fractures.展开更多
BACKGROUND Gastric ulcer perforation is a critical condition that can lead to significant morbidity and mortality if not promptly addressed.It is often the result of chronic peptic ulcer disease,which is characterized...BACKGROUND Gastric ulcer perforation is a critical condition that can lead to significant morbidity and mortality if not promptly addressed.It is often the result of chronic peptic ulcer disease,which is characterized by a breach in the gastric wall due to ulceration.Surgical intervention is essential for managing this life-threatening complication.However,the optimal surgical technique remains debatable among clinicians.Various methods have been employed,including simple closure,omental patch repair,and partial gastrectomy,each with distinct advantages and disadvantages.Understanding the comparative efficacy and postoperative outcomes of these techniques is crucial for improving patient care and surgical decision-making.This study addresses the need for a comprehensive analysis in this area.AIM To compare the efficacy and postoperative complications of different surgical methods for the treatment of gastric ulcer perforation.METHODS A retrospective analysis was conducted on 120 patients who underwent surgery for gastric ulcer perforation between September 2020 and June 2023.The patients were divided into three groups based on the surgical method:Simple closure,omental patch repair,and partial gastrectomy.The primary outcomes were the operative success rate and incidence of postoperative complications.Secondary outcomes included the length of hospital stay,recovery time,and long-term quality of life.RESULTS The operative success rates for simple closure,omental patch repair,and partial gastrectomy were 92.5%,95%,and 97.5%,respectively.Postoperative complications occurred in 20%,15%,and 17.5%of patients in each group,respectively.The partial gastrectomy group showed a significantly longer operative time(P<0.001)but the lowest rate of ulcer recurrence(2.5%,P<0.05).The omental patch repair group demonstrated the shortest hospital stay(mean 7.2 days,P<0.05)and fastest recovery time.CONCLUSION While all three surgical methods showed high success rates,omental patch repair demonstrated the best overall outcomes,with a balance of high efficacy,low complication rates,and shorter recovery time.However,the choice of the surgical method should be tailored to individual patient factors and the surgeon’s expertise.展开更多
BACKGROUND Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract,and gastric gastrointestinal stromal tumors(gGISTs)account for the majority of these tumors.Currently,end...BACKGROUND Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract,and gastric gastrointestinal stromal tumors(gGISTs)account for the majority of these tumors.Currently,endoscopic removal(ER)is increasingly adopted as a minimally invasive treatment.However,postoperative perforation remains a critical complication,necessitating robust prediction tools.AIM To identify the risk factors and develop a validated nomogram for predicting perforation after ER of gGISTs.METHODS This retrospective study analyzed the patients undergoing ER at Fuyang People’s Hospital from 2019 to 2024.Clinical data,including tumor size,location,and procedural details,were collected and analyzed.The risk factors were identified via univariate and multivariate logistic regression,and a nomogram was developed.Both internal and external validations were performed,and the model performance was assessed by receiver operating characteristic curves and calibration plots.RESULTS Among 301 patients,the perforation rate was 6.3%.Multivariate analysis identified tumor size(odds ratio=4.699,95%confidence interval:2.382-9.267,P=0.001)and cardia/fundus location(odds ratio=3.492,95%confidence interval:1.121-10.875,P=0.031)as independent predictors.A nomogram was constructed and achieved good predictive performance in both the training(area under the curve=0.881)and validation sets(area under the curve=0.878).CONCLUSION This study identified that tumor size and location were independent risk factors,and provides a clinically actionable nomogram for evaluating and predicting postoperative perforation risk in gGISTs treated with ER,facilitating preprocedural planning and risk monitoring.展开更多
Group B Streptococcus(GBS;Streptococcus agalactiae)is a gram-positive coccus that colonizes the gastrointestinal and genital tracts in adults,as well as the upper respiratory tract in infants.While it has been thought...Group B Streptococcus(GBS;Streptococcus agalactiae)is a gram-positive coccus that colonizes the gastrointestinal and genital tracts in adults,as well as the upper respiratory tract in infants.While it has been thought that GBS only results in invasive disease in pregnant females and neonates,recent literature has suggested an increasing incidence of invasive GBS among non-pregnant individuals within the United States.展开更多
BACKGROUND Gastrointestinal(GI)perforation(GP)repair is a surgical procedure to promptly seal perforations in the GI tract to prevent further leakage.After surgery,patients often experience a high metabolic state due ...BACKGROUND Gastrointestinal(GI)perforation(GP)repair is a surgical procedure to promptly seal perforations in the GI tract to prevent further leakage.After surgery,patients often experience a high metabolic state due to trauma,infection,and posto-perative stress.In the Enhanced Recovery After Surgery(ERAS)protocol,early enteral nutrition is a key strategy for promoting postoperative recovery.Com-pared with parenteral nutrition,enteral nutrition more effectively meets the physiological needs of the GI system,promotes the recovery of gut function,and reduces the risk of GI infections.AIM To evaluate the clinical efficacy of early enteral nutrition support in patients undergoing GP repair within the ERAS protocol.METHODS This retrospective study analyzed 66 patients who underwent GP repair.Patients were divided into a control group(n=32),managed with a traditional nutritional regimen,primarily consisting of total parenteral nutrition;and an observation group(n=34),which included those who received early enteral nutrition support as part of the ERAS protocol.This study examined the time to first postoperative flatus and bowel movement,changes in nutritional and immune function,inflam-matory markers on postoperative days 1 and 5,and adverse reactions.RESULTS The observation group had significantly shorter times to the first postoperative flatus and bowel movement than the control group(P<0.05).On postoperative day 5,the observation group demonstrated higher nutritional and immune function levels than the control group(P<0.05),while C-reactive protein levels were significantly lower(P<0.05).The overall incidence of adverse reactions in the observation group was 8.82%(3/34),which was lower than the 28.13%(9/32)observed in the control group(P<0.05).CONCLUSION Early enteral nutritional support facilitates GI recovery after GP repair.It improves nutritional status,enhances immune function,and attenuates inflammatory responses while also demonstrating a favorable safety profile.展开更多
AIM:To investigate the clinical signs of blepharokeratoconjunctivitis(BKC)and evaluate the efficacy of penetrating keratoplasty(PKP)for the disease.METHODS:Sixteen patients(16 eyes)with BKC complicated by corneal perf...AIM:To investigate the clinical signs of blepharokeratoconjunctivitis(BKC)and evaluate the efficacy of penetrating keratoplasty(PKP)for the disease.METHODS:Sixteen patients(16 eyes)with BKC complicated by corneal perforation hospitalised at Shandong Eye Hospital were retrospectively analyzed.All patients received PKP.Participants were assessed for symptoms,clinical manifestations,the activity and damage grading of BKC.A paired t-test was used to compare the uncorrected visual acuity(UCVA)before and after surgery for the perforated eye.RESULTS:The mean age of the patients was 16.3y.Blurred vision is the most common discomfort,followed by redness,and then photophobia.The duration of ocular discomfort lasted for 3.2y,on average.Three(18.8%)participants were associated with rosacea,while 11(68.8%)patients had recurrent chalazion or hordeolum.Demodex in eyelash follicles was positive in 11(68.8%)cases.All corneal perforations were≤3.0 mm in diameter.The perforation was located mainly in the inferior cornea(68.8%).The mean area of corneal vascularisation was 3.0 quadrants.All patients manifested bilateral BKC,with the perforated eyes ranked as severely damaged and presenting with severe inflammation.Most contralateral eyes manifested mild damage with no active inflammation.Majority(68.8%)of the perforated eyes were treated with PKP using a minimal graft.The UCVA increased significantly at the final follow-up(mean,21mo;P<0.001),with the manifestation of BKC alleviated greatly.None of the patients developed immune rejection or other serious complications.CONCLUSION:BKC combined with corneal perforation occurs mainly among young people with a long history of ocular discomfort.PKP,especially using a minimal graft,is an effective and safe option for treating the disease.展开更多
Janus vesicles,unique nanostructures,have attracted significant attention for their diverse applications in biomedical and microfluidic systems.In practical micro-nano systems,flow and electric fields often coexist,an...Janus vesicles,unique nanostructures,have attracted significant attention for their diverse applications in biomedical and microfluidic systems.In practical micro-nano systems,flow and electric fields often coexist,and the perforation dynamics of Janus vesicles exhibit complex motion due to their synergistic effects.Studying Janus vesicle perforation dynamics under the combined influence of fluid flow and electric fields provides valuable insights into their applications in drug delivery,catalyst delivery,and controlled release.This study focuses on the perforation dynamics and directional motion of Janus vesicles in microchannels,emphasizing how electric field strength and charge distribution on the membrane influence vesicle migration,deformation,and trajectories.Results show that when electromagnetic forces and flow-driven forces align,increasing electric field strength promotes vesicle migration and perforation.Vesicle migration is correlated with charge distribution on the membrane,with broader distributions resulting in more pronounced migration.When electric field strength remains constant,charge distribution has little effect on vesicle deformation.Conversely,when electromagnetic forces and flow-driven forces oppose,increasing electric field strength inhibits vesicle migration.At a specific potential difference,charged vesicles cease movement before reaching the perforation site,indicating the critical potential for perforation.The study also reveals that the direction of the electric field significantly affects vesicle migration direction.Adjusting potential values at microchannel boundaries can control the directional movement of Janus vesicles.This research provides new insights into Janus vesicle behavior in complex environments and deepens understanding of their potential as drug carriers for delivery and targeted therapy.展开更多
In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforatio...In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforation using ANSYS/LS-DYNA simulation technology. The combination of critical perforation parameters for double casing is obtained by studying the influencing factors of the jet-forming process,perforation depth, diameter, and stress changes of the inner and outer casing. The single-target perforation experiments under high-temperature and high-pressure(HTHP) conditions and ground full-scale ring target perforation tests are designed to verify the accuracy of numerical simulation results. The reduced factor is adopted as the quantitative measure of perforation depth and diameter for different types of perforation charge under different conditions. The results show that the perforation depth reduction increases with temperature and pressure, and the reduced factor is between 0.67 and 0.87 under HTHP conditions of 130℃/44 MPa and 137℃/60 MPa. Comparing the results of the numerical simulation and the full-scale test correction, the maximum error is less than 8.91%, and this numerical simulation has strong reliability. This research provides a basis for a reasonable range of double-cased perforation parameters and their optimal selection.展开更多
Tri-axial fracturing studies were carried out to understand the impact of lateral mechanical parameters on fracture propagation from multiple in-plane perforations in horizontal wells. Additionally, the discussion cov...Tri-axial fracturing studies were carried out to understand the impact of lateral mechanical parameters on fracture propagation from multiple in-plane perforations in horizontal wells. Additionally, the discussion covered the effects of geology, treatment, and perforation characteristics on the non-planar propagation behavior. According to experimental findings, two parallel transverse fractures can be successfully initiated from in-plane perforation clusters in the horizontal well because of the in-plane perforation, the guide nonuniform fishbone structure fracture propagation still can be exhibited. The emergence of transverse fractures and axial fractures combined as complex fractures under low horizontal principal stress difference and large pump rate conditions. The injection pressure was also investigated, and the largest breakdown pressure can be also found for samples under these conditions.The increase in perforation number or decrease in the cluster spacing could provide more chances to increase the complexity of the target stimulated zone, thus affecting the pressure fluctuation. In a contrast, the increase in fracturing fluid viscosity can reduce the multiple fracture complexity. The fracture propagation is significantly affected by the change in the rock mechanical properties. The fracture geometry in the high brittle zone seems to be complicated and tends to induce fracture reorientation from the weak-brittle zone. The stress shadow effect can be used to explain the fracture attraction, branch, connection, and repulsion in the multiple perforation clusters for the horizontal well.The increase in the rock heterogeneity can enhance the stress shadow effect, resulting in more complex fracture geometry. In addition, the variable density perforation and temporary plugging fracturing were also conducted, demonstrating higher likelihood for non-uniform multiple fracture propagation. Thus, to increase the perforation efficiency along the horizontal well, it is necessary to consider the lateral fracability of the horizontal well on target formation.展开更多
Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing operations.Optimizing perforation designs is critical for augmenting the...Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing operations.Optimizing perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas production.In this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design parameters.The model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical report.Real-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation types.Our simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation lengths.The findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation length.Moreover,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.展开更多
This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion w...This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion with multi-cluster sand jetting perforation.The effects of temporary plugging agent(TPA)particle size,TPA concentration,single-cluster perforation number and cluster number on plugging pressure,multi-fracture diversion pattern and distribution of TPAs were investigated.A combination of TPAs with small particle sizes within the fracture and large particle sizes within the segment is conducive to increasing the plugging pressure and promoting the diversion of multi-fractures.The addition of fibers can quickly achieve ultra-high pressure,but it may lead to longitudinal fractures extending along the wellbore.The temporary plugging peak pressure increases with an increase in the concentration of the TPA,reaching a peak at a certain concentration,and further increases do not significantly improve the temporary plugging peak pressure.The breaking pressure and temporary plugging peak pressure show a decreasing trend with an increase in single-cluster perforation number.A lower number of single-cluster perforations is beneficial for increasing the breaking pressure and temporary plugging peak pressure,and it has a more significant control on the propagation of multi-cluster fractures.A lower number of clusters is not conducive to increasing the total number and complexity of artificial fractures,while a higher number of clusters makes it difficult to achieve effective plugging.The TPAs within the fracture is mainly concentrated in the complex fracture areas,especially at the intersections of fractures.Meanwhile,the TPAs within the segment are primarily distributed near the perforation cluster apertures which initiated complex fractures.展开更多
文摘BACKGROUND Motorcycle accidents often result in abdominal trauma in patients seeking emergency care.Injuries to the hollow viscera,including the duodenum,jejunum,urinary bladder,and colorectum,are relatively common.In contrast,owing to the protective function of the anterior rib cage,gastric rupture is exceptionally rare,with an incidence of<1.7%.Gastric rupture typically occurs in the anterior wall and rarely presents as multiple ruptures.This report describes an unusual case of multiple gastric ruptures resulting from blunt trauma.CASE SUMMARY A 21-year-old man,who was involved in a motorcycle collision at 70 km/hour after consuming a large meal,presented with hypotension.Physical examination revealed abdominal tenderness.Laboratory test results indicated elevated amylase,lipase,and liver enzyme levels.Computed tomography showed pneumoperitoneum,hemoperitoneum,and gastric wall discontinuation,suggesting gastric perforation alongside pancreatic,splenic,and hepatic injuries.Angiographic embolization was performed because of active contrast leakage in the left gastric and right gastroepiploic arteries.Emergency laparotomy revealed substantial blood loss,hematoma,and gastric contents scattered throughout the abdominal cavity.Two 10 cm gastric perforations in the anterior and posterior walls were identified,as well as severe liver damage,splenic injury,and pancreatic contusion.Surgical interventions included primary closure of the gastric wall,splenectomy,and partial hepatectomy.After temporary abdominal closure,the patient underwent a second surgery without further bleeding.The gastric repair site was resected and reinforced for optimal tissue healing.CONCLUSION Gastric rupture following blunt trauma is fatal.However,patients without severe complications can recover through surgical interventions and postoperative care.
文摘Colonoscopy represents a safe procedure that is widely used in medical practice either to diagnose or treat various gastrointestinal diseases.During the last few years,the incidence rate of perforations in colonoscopic procedures has increased,especially in therapeutic colonoscopies.The recent advancements in endoscopic techniques and gastrointestinal tumoral resection procedures such as endoscopic mucosal resection,endoscopic full-thickness resection,and endoscopic submucosal dissection(ESD)could be a risk factor for this increased risk.The incidence rate of mortality of serious colonoscopic perforations is 7.1%.The management plan for these perforations starts with conservative treatment in mild cases,endoscopic closure,and surgical management in severe cases.Recently,endoluminal vacuum therapy was found to be effective in the management of colorectal perforations and this has been reported in multiple case reports.This editorial provides an overview of the current guidelines for the management of iatrogenic colorectal perforations.These insights are from the perspectives of endoscopists and gastroenterologists.We also present a management algorithm based on the guidelines of the European Society of Gastrointestinal Endoscopy,the American Gastroenterological Association,and the World Society of Emergency Surgery.We also discussed in brief the use of endoluminal vacuum therapy in colorectal perforations.
文摘A theoretical analysis on the perforation of Weldox 460E steel plates struck by flat-nosed projectiles is presented using a previously developed model within a unified framework.This model contains a dimensionless empirical equation to describe the variation of energy absorbed through global deformation as a function of impact velocity.The study further investigates the energy absorption mechanisms of Weldox 460E steel plates,with particular focus on the“plateau”phenomenon,i.e.,limited increase in ballistic limit with increasing plate thickness.This phenomenon is explained and compared with results from previously studied 2024-T351 aluminium plates.The model predictions agree well with experimental data for Weldox 460E steel plates impacted by flat-nosed projectiles,including:relationship between global deformation and impact velocity,ballistic limit,residual velocity,and critical conditions for the transition of failure modes.Moreover,the model effectively predicts the“plateau”phenomenon observed in intermediate plate thickness range.It is also found that the indentation absorption energy contributes a significantly larger fraction of the total absorption energy in Weldox 460E steel plates perforated by flat-nosed projectiles than in 2024-T351 aluminium plates,due to the differences in material properties.
文摘BACKGROUND Intestinal obstruction(IO)in pregnancy,though rare(1:1500-1:66000),carries high maternal(6%-10%)and fetal mortality(26%).Adhesions from prior surgery are the leading cause.Diagnosis is often delayed due to symptom overlap with nor-mal pregnancy,increasing risks of perforation and sepsis.CASE SUMMARY A 25-year-old gravida 2 para 1 woman at 28 weeks of gestation presented with 1-week constipation,feculent vomiting,and abdominal distension.She had a history of exploratory laparotomy in 2015 for blunt abdominal trauma.The diagnosis of IO in pregnancy was confirmed via abdominopelvic ultrasound and clinical findings.Interventions included conservative measures(nasogastric tube decompression,enemas)followed by emergency laparotomy with bowel resec-tion/anastomosis.Despite surgical management,the patient succumbed to septic shock.CONCLUSION High clinical suspicion,expedited cross-sectional imaging(computed tomogra-phy/Magnetic resonance imaging),and emergent surgery are critical to reduce mortality.
文摘It has been experimentally observed that,in the perforation of metal plates by a flat-nosed projectile,there exists a plateau phenomenon where the ballistic limit increases slightly with increasing plate thickness,which is related to a change in the mode of failure.No theoretical model has so far explained this phenomenon satisfactorily.This paper presents a combined numerical and theoretical study on the perforation of 2024-T351 aluminum plates struck by flat-nosed projectiles.First,numerical simulations are performed to investigate the failure mechanisms/deformation modes of the aluminum plates.Then,a theoretical model is proposed based on the numerical results and the experimental observations within a unified framework.The model takes into account the main energy absorbing mechanisms and the corresponding energies absorbed are determined analytically.In particular,a dimensionless equation is suggested to describe the relationship between global deformations and impact velocity.It transpires that the model predictions are in good agreement with the test data and the numerical results for the perforation of 2024-T351 aluminum plates struck by rigid flat-nosed projectiles in terms of residual velocity,ballistic limit,relationship between global deformations and impact velocity,and transition of failure modes.It also transpires that the present model can predict the“plateau”phenomenon,which shows a slight increase in ballistic limit as plate thickness increases.Furthermore,the energy absorption mechanisms are discussed on the basis of the theoretical analysis.
基金supported by the Sinopec Technology Research and Development Project(No.30000000-22-ZC0607-0235,No.33550000-22-ZC0607-0009)the National Natural Science Foundation of China(No.52334002).
文摘Natural gas hydrate widely exists in the South China Sea as clean energy.A three-phase transition layer widely exists in low permeability Class I hydrates in the Shenhu offshore area.Therefore,taking into account the low-permeability characteristics with an average permeability of 5.5 mD and moderate heterogeneity,a 3-D geological model of heterogeneous Class I hydrate reservoirs with three-phase transition layers is established by Kriging interpolation and stochastic modeling method,and a numerical simulation model is used to describe the depressurization production performance of the reservoir.With the development of depressurization,a specific range of complete decomposition zones appear both in the hydrate and transition layers.The entire decomposition zone of the whole reservoir tends to outward and upward diffusion.There is apparent methane escape in the three-phase transition layer.Due to the improvement of local permeability caused by the phase transition of hydrate dissociation,some methane accumulation occurs at the bottom of the hydrate layer,forming a local methane enrichment zone.The methane migration trends in reservoirs are mainly characterized by movement toward production wells and hydrate layers under the influence of gravity.However,due to the permeability limitation of hydrate reservoirs,many fluids have not been effectively produced and remain in the reservoir.Therefore,to improve the effective pressure drop of the reservoir,the perforation method and pressure reduction method were optimized by analyzing the influencing factors based on the gas production rate.The comparative study demonstrates that perforating through the free gas layer combined with one-time depressurization can enhance the effective depressurization and improve production performance.The gas production rate from perforating through the free gas layer can be twice as high as that from perforating through the transition layer.This study can provide theoretical support for the utilization of marine energy.
文摘Several issues should be considered before the surgical treatment of gastric ulcer perforations,including morbidity,mortality,and recurrence.However,an oftenoverlooked issue is determining the cause of the perforation.When the perforation is secondary to an underlying and undiagnosed malignancy,stomach resection inadequately treats the oncological disease and may increase postoperative morbidity and require re-surgery.
文摘BACKGROUND Acute abdominal pain is one of the most common gastrointestinal symptoms.The etiology of acute abdomen can be challenging for gastroenterologists to establish.Cecal foreign body is a rare cause of cecal perforation.CASE SUMMARY We report a 35-year-old male from China who initially exhibited symptoms suggestive of acute appendicitis.However,during a minimally invasive colonoscopy procedure,the authors found that a wooden toothpick caused the perforation.The patient presented to our emergency department with a 2 days history of right lower abdominal pain and low grade fever.The patient was in good health and had eaten fish 2 days earlier.Physical examination revealed mild pain with positive rebound tenderness in the right lower abdomen.However,computed tomography of the abdomen confirmed a strip of high-density shadows protruding beyond the intestinal cavity outline,with a small amount of peritoneal seepage in the ileocecal area.Combined with the medical history,the possibility of foreign body perforation by a fishbone and peripheral peritonitis were considered.However,the high-density shadow was identified as a wooden toothpick,which was removed via a minimally invasive procedure using a foreign body forceps under colonoscopy.The patient's condition improved significantly within 5 days after treatment.CONCLUSION We emphasize the importance of a detailed patient history,accurate diagnosis and proper treatment in patients with acute abdomen.
基金Supported by National Natural Science Foundation of China Joint Fund for Enterprise Innovation and Development(U24B6002).
文摘Based on the Low Frequency Distributed Acoustic Sensing(LF-DAS)fiber optic monitoring and downhole hawk-eye imaging,the fluid and sand distribution and perforation erosion of all clusters during hydraulic fracturing were evaluated,and then a fully coupled wellbore-perforation-fracture numerical model was established to simulate the whole process of sand-carrying fluid migration and analyze key influencing factors.The proppant and fracturing fluid exhibit divergent flow pathways during multi-staged,multi-cluster fracturing in horizontal wells,resulting in significant heterogeneity in the fluid-proppant distribution among clusters.Perforation erosion is prevalent,and perforation erosion and sand inflow ratio have phase bias.The trajectory of proppant transport is controlled by the combined effects of inertia of particle migration and gravity settlement.The inertial effect is dominant at the wellbore heel,where the fluid flow rate is high,hindering particles turning into perforations and causing uneven sand distribution among clusters.The gravity settlement is more pronounced toward the wellbore toe,where the fluid flow rate is low,leading to enhanced phase-bias of slurry distribution and perforation erosion.Increasing the pumping rate reduces the influence of gravity settlement,mitigating the phase bias of sand inflow and perforation erosion.However,the large pumping rate limits the sand inflow efficiency near the heel clusters,and more proppants accumulate towards the toe clusters.High-viscosity fluids improve particle suspension,achieving more uniform proppant placement within wellbore and fractures.Larger particle sizes exacerbate sand inflow differences among clusters and perforations,limiting the proppant placement range within fractures.
文摘BACKGROUND Gastric ulcer perforation is a critical condition that can lead to significant morbidity and mortality if not promptly addressed.It is often the result of chronic peptic ulcer disease,which is characterized by a breach in the gastric wall due to ulceration.Surgical intervention is essential for managing this life-threatening complication.However,the optimal surgical technique remains debatable among clinicians.Various methods have been employed,including simple closure,omental patch repair,and partial gastrectomy,each with distinct advantages and disadvantages.Understanding the comparative efficacy and postoperative outcomes of these techniques is crucial for improving patient care and surgical decision-making.This study addresses the need for a comprehensive analysis in this area.AIM To compare the efficacy and postoperative complications of different surgical methods for the treatment of gastric ulcer perforation.METHODS A retrospective analysis was conducted on 120 patients who underwent surgery for gastric ulcer perforation between September 2020 and June 2023.The patients were divided into three groups based on the surgical method:Simple closure,omental patch repair,and partial gastrectomy.The primary outcomes were the operative success rate and incidence of postoperative complications.Secondary outcomes included the length of hospital stay,recovery time,and long-term quality of life.RESULTS The operative success rates for simple closure,omental patch repair,and partial gastrectomy were 92.5%,95%,and 97.5%,respectively.Postoperative complications occurred in 20%,15%,and 17.5%of patients in each group,respectively.The partial gastrectomy group showed a significantly longer operative time(P<0.001)but the lowest rate of ulcer recurrence(2.5%,P<0.05).The omental patch repair group demonstrated the shortest hospital stay(mean 7.2 days,P<0.05)and fastest recovery time.CONCLUSION While all three surgical methods showed high success rates,omental patch repair demonstrated the best overall outcomes,with a balance of high efficacy,low complication rates,and shorter recovery time.However,the choice of the surgical method should be tailored to individual patient factors and the surgeon’s expertise.
文摘BACKGROUND Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract,and gastric gastrointestinal stromal tumors(gGISTs)account for the majority of these tumors.Currently,endoscopic removal(ER)is increasingly adopted as a minimally invasive treatment.However,postoperative perforation remains a critical complication,necessitating robust prediction tools.AIM To identify the risk factors and develop a validated nomogram for predicting perforation after ER of gGISTs.METHODS This retrospective study analyzed the patients undergoing ER at Fuyang People’s Hospital from 2019 to 2024.Clinical data,including tumor size,location,and procedural details,were collected and analyzed.The risk factors were identified via univariate and multivariate logistic regression,and a nomogram was developed.Both internal and external validations were performed,and the model performance was assessed by receiver operating characteristic curves and calibration plots.RESULTS Among 301 patients,the perforation rate was 6.3%.Multivariate analysis identified tumor size(odds ratio=4.699,95%confidence interval:2.382-9.267,P=0.001)and cardia/fundus location(odds ratio=3.492,95%confidence interval:1.121-10.875,P=0.031)as independent predictors.A nomogram was constructed and achieved good predictive performance in both the training(area under the curve=0.881)and validation sets(area under the curve=0.878).CONCLUSION This study identified that tumor size and location were independent risk factors,and provides a clinically actionable nomogram for evaluating and predicting postoperative perforation risk in gGISTs treated with ER,facilitating preprocedural planning and risk monitoring.
文摘Group B Streptococcus(GBS;Streptococcus agalactiae)is a gram-positive coccus that colonizes the gastrointestinal and genital tracts in adults,as well as the upper respiratory tract in infants.While it has been thought that GBS only results in invasive disease in pregnant females and neonates,recent literature has suggested an increasing incidence of invasive GBS among non-pregnant individuals within the United States.
文摘BACKGROUND Gastrointestinal(GI)perforation(GP)repair is a surgical procedure to promptly seal perforations in the GI tract to prevent further leakage.After surgery,patients often experience a high metabolic state due to trauma,infection,and posto-perative stress.In the Enhanced Recovery After Surgery(ERAS)protocol,early enteral nutrition is a key strategy for promoting postoperative recovery.Com-pared with parenteral nutrition,enteral nutrition more effectively meets the physiological needs of the GI system,promotes the recovery of gut function,and reduces the risk of GI infections.AIM To evaluate the clinical efficacy of early enteral nutrition support in patients undergoing GP repair within the ERAS protocol.METHODS This retrospective study analyzed 66 patients who underwent GP repair.Patients were divided into a control group(n=32),managed with a traditional nutritional regimen,primarily consisting of total parenteral nutrition;and an observation group(n=34),which included those who received early enteral nutrition support as part of the ERAS protocol.This study examined the time to first postoperative flatus and bowel movement,changes in nutritional and immune function,inflam-matory markers on postoperative days 1 and 5,and adverse reactions.RESULTS The observation group had significantly shorter times to the first postoperative flatus and bowel movement than the control group(P<0.05).On postoperative day 5,the observation group demonstrated higher nutritional and immune function levels than the control group(P<0.05),while C-reactive protein levels were significantly lower(P<0.05).The overall incidence of adverse reactions in the observation group was 8.82%(3/34),which was lower than the 28.13%(9/32)observed in the control group(P<0.05).CONCLUSION Early enteral nutritional support facilitates GI recovery after GP repair.It improves nutritional status,enhances immune function,and attenuates inflammatory responses while also demonstrating a favorable safety profile.
基金Supported by Key Technology Research and Development Program of Shandong Province(No.2022CXGC010505)Natural Science Foundation of Shandong Province(No.ZR2019BH065)+1 种基金Taishan Scholars Program(No.20221110)the Innovation Project of Shandong Academy of Medical Sciences.
文摘AIM:To investigate the clinical signs of blepharokeratoconjunctivitis(BKC)and evaluate the efficacy of penetrating keratoplasty(PKP)for the disease.METHODS:Sixteen patients(16 eyes)with BKC complicated by corneal perforation hospitalised at Shandong Eye Hospital were retrospectively analyzed.All patients received PKP.Participants were assessed for symptoms,clinical manifestations,the activity and damage grading of BKC.A paired t-test was used to compare the uncorrected visual acuity(UCVA)before and after surgery for the perforated eye.RESULTS:The mean age of the patients was 16.3y.Blurred vision is the most common discomfort,followed by redness,and then photophobia.The duration of ocular discomfort lasted for 3.2y,on average.Three(18.8%)participants were associated with rosacea,while 11(68.8%)patients had recurrent chalazion or hordeolum.Demodex in eyelash follicles was positive in 11(68.8%)cases.All corneal perforations were≤3.0 mm in diameter.The perforation was located mainly in the inferior cornea(68.8%).The mean area of corneal vascularisation was 3.0 quadrants.All patients manifested bilateral BKC,with the perforated eyes ranked as severely damaged and presenting with severe inflammation.Most contralateral eyes manifested mild damage with no active inflammation.Majority(68.8%)of the perforated eyes were treated with PKP using a minimal graft.The UCVA increased significantly at the final follow-up(mean,21mo;P<0.001),with the manifestation of BKC alleviated greatly.None of the patients developed immune rejection or other serious complications.CONCLUSION:BKC combined with corneal perforation occurs mainly among young people with a long history of ocular discomfort.PKP,especially using a minimal graft,is an effective and safe option for treating the disease.
基金financially supported by the National Natural Science Foundation of China(No.2247030172)。
文摘Janus vesicles,unique nanostructures,have attracted significant attention for their diverse applications in biomedical and microfluidic systems.In practical micro-nano systems,flow and electric fields often coexist,and the perforation dynamics of Janus vesicles exhibit complex motion due to their synergistic effects.Studying Janus vesicle perforation dynamics under the combined influence of fluid flow and electric fields provides valuable insights into their applications in drug delivery,catalyst delivery,and controlled release.This study focuses on the perforation dynamics and directional motion of Janus vesicles in microchannels,emphasizing how electric field strength and charge distribution on the membrane influence vesicle migration,deformation,and trajectories.Results show that when electromagnetic forces and flow-driven forces align,increasing electric field strength promotes vesicle migration and perforation.Vesicle migration is correlated with charge distribution on the membrane,with broader distributions resulting in more pronounced migration.When electric field strength remains constant,charge distribution has little effect on vesicle deformation.Conversely,when electromagnetic forces and flow-driven forces oppose,increasing electric field strength inhibits vesicle migration.At a specific potential difference,charged vesicles cease movement before reaching the perforation site,indicating the critical potential for perforation.The study also reveals that the direction of the electric field significantly affects vesicle migration direction.Adjusting potential values at microchannel boundaries can control the directional movement of Janus vesicles.This research provides new insights into Janus vesicle behavior in complex environments and deepens understanding of their potential as drug carriers for delivery and targeted therapy.
基金the support of the Foundation of Natural Science Foundation of Shaanxi Province, Grant/ Award nos. 2023-JC-YB-361National Natural Science Foundation (Number 52104033)。
文摘In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforation using ANSYS/LS-DYNA simulation technology. The combination of critical perforation parameters for double casing is obtained by studying the influencing factors of the jet-forming process,perforation depth, diameter, and stress changes of the inner and outer casing. The single-target perforation experiments under high-temperature and high-pressure(HTHP) conditions and ground full-scale ring target perforation tests are designed to verify the accuracy of numerical simulation results. The reduced factor is adopted as the quantitative measure of perforation depth and diameter for different types of perforation charge under different conditions. The results show that the perforation depth reduction increases with temperature and pressure, and the reduced factor is between 0.67 and 0.87 under HTHP conditions of 130℃/44 MPa and 137℃/60 MPa. Comparing the results of the numerical simulation and the full-scale test correction, the maximum error is less than 8.91%, and this numerical simulation has strong reliability. This research provides a basis for a reasonable range of double-cased perforation parameters and their optimal selection.
基金financially supported by the National Natural Science Foundation of China (51704324, 52374027)Natural Science Foundation of Shandong Province (ZR2023ME158, ZR2022ME025)Open Fund of Key Laboratory of Tectonics and Petroleum Resources (TPR-2020-14)。
文摘Tri-axial fracturing studies were carried out to understand the impact of lateral mechanical parameters on fracture propagation from multiple in-plane perforations in horizontal wells. Additionally, the discussion covered the effects of geology, treatment, and perforation characteristics on the non-planar propagation behavior. According to experimental findings, two parallel transverse fractures can be successfully initiated from in-plane perforation clusters in the horizontal well because of the in-plane perforation, the guide nonuniform fishbone structure fracture propagation still can be exhibited. The emergence of transverse fractures and axial fractures combined as complex fractures under low horizontal principal stress difference and large pump rate conditions. The injection pressure was also investigated, and the largest breakdown pressure can be also found for samples under these conditions.The increase in perforation number or decrease in the cluster spacing could provide more chances to increase the complexity of the target stimulated zone, thus affecting the pressure fluctuation. In a contrast, the increase in fracturing fluid viscosity can reduce the multiple fracture complexity. The fracture propagation is significantly affected by the change in the rock mechanical properties. The fracture geometry in the high brittle zone seems to be complicated and tends to induce fracture reorientation from the weak-brittle zone. The stress shadow effect can be used to explain the fracture attraction, branch, connection, and repulsion in the multiple perforation clusters for the horizontal well.The increase in the rock heterogeneity can enhance the stress shadow effect, resulting in more complex fracture geometry. In addition, the variable density perforation and temporary plugging fracturing were also conducted, demonstrating higher likelihood for non-uniform multiple fracture propagation. Thus, to increase the perforation efficiency along the horizontal well, it is necessary to consider the lateral fracability of the horizontal well on target formation.
基金support from the National Natural Science Foundation of China(Grant Nos.52178324,12102059)the China Postdoctoral Science Foundation(Grant No.2023M743604)+1 种基金the Beijing Natural Science Foundation(Grant No.3212027),the National Key R&D Program of China(Grant No.2023YFC3007203)the 2019 Foreign Experts Plan of Hebei Province.
文摘Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing operations.Optimizing perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas production.In this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design parameters.The model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical report.Real-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation types.Our simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation lengths.The findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation length.Moreover,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.
基金Supported by the National Natural Science Foundation of China(51974332).
文摘This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion with multi-cluster sand jetting perforation.The effects of temporary plugging agent(TPA)particle size,TPA concentration,single-cluster perforation number and cluster number on plugging pressure,multi-fracture diversion pattern and distribution of TPAs were investigated.A combination of TPAs with small particle sizes within the fracture and large particle sizes within the segment is conducive to increasing the plugging pressure and promoting the diversion of multi-fractures.The addition of fibers can quickly achieve ultra-high pressure,but it may lead to longitudinal fractures extending along the wellbore.The temporary plugging peak pressure increases with an increase in the concentration of the TPA,reaching a peak at a certain concentration,and further increases do not significantly improve the temporary plugging peak pressure.The breaking pressure and temporary plugging peak pressure show a decreasing trend with an increase in single-cluster perforation number.A lower number of single-cluster perforations is beneficial for increasing the breaking pressure and temporary plugging peak pressure,and it has a more significant control on the propagation of multi-cluster fractures.A lower number of clusters is not conducive to increasing the total number and complexity of artificial fractures,while a higher number of clusters makes it difficult to achieve effective plugging.The TPAs within the fracture is mainly concentrated in the complex fracture areas,especially at the intersections of fractures.Meanwhile,the TPAs within the segment are primarily distributed near the perforation cluster apertures which initiated complex fractures.
