Numerical Analysis of Perforation during Hydraulic Fracture Initiation Based on Continuous-Discontinuous Element Method

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.

Extreme massive hydraulic fracturing in deep coalbed methane horizontal wells:A case study of the Linxing Block,eastern Ordos Basin,NW China

Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the concept of large-scale stimulation by fracture network,balanced propagation and effective support of fracture network in fracturing design and developed the extreme massive hydraulic fracturing technique for deep coalbed methane(CBM)horizontal wells.This technique involves massive injection with high pumping rate+high-intensity proppant injection+perforation with equal apertures and limited flow+temporary plugging and diverting fractures+slick water with integrated variable viscosity+graded proppants with multiple sizes.The technique was applied in the pioneering test of a multi-stage fracturing horizontal well in deep CBM of Linxing Block,eastern margin of the Ordos Basin.The injection flow rate is 18 m^(3)/min,proppant intensity is 2.1 m^(3)/m,and fracturing fluid intensity is 16.5 m^(3)/m.After fracturing,a complex fracture network was formed,with an average fracture length of 205 m.The stimulated reservoir volume was 1987×10^(4)m^(3),and the peak gas production rate reached 6.0×10^(4)m^(3)/d,which achieved efficient development of deep CBM.

Conquer coronary artery perforation with magic hands

Coronary artery perforation(CAP) poses a significant challenge for interventional cardiologists. Management of CAP depends on the location and severity of the perforation. The conventional method for addressing the perforation of large vessels involves the placement of a covered stent, while the perforation of distal and collateral vessels is typically managed using coils, autologous skin, subcutaneous fat, microspheres, gelatin sponge, thrombin or other substances. However, the above techniques have certain limitations and are not applicable in all scenarios. Our team has developed a range of innovative strategies for effectively managing CAP. This article provides an insightful review of the various tips and tricks for the treatment of CAP.

Influence of Blade Number on the Performance of Hydraulic Turbines in the Transition Stage

To analyze the effect of blade number on the performance of hydraulic turbines during the transient stage in which theflow rate is not constant,six hydraulic turbines with different blade numbers are considered.The instantaneous hydraulic performance of the turbine and the pressure pulsation acting on the impeller are investigated numerically by using the ANSYS CFX software.The ensuing results are compared with the outcomes of experimental tests.It is shown that thefluctuation range of the pressure coefficient increases with time,but the corresponding range for the transient hydraulic efficiency decreases gradually when theflow velocity transits to larger values.During the transition to smallflow velocity,thefluctuation range of the pressure coefficient gradually decreases as time passes,but the correspondingfluctuation range of its transient hydraulic efficiency gradually becomes larger.Thefluctuation range in the Z9 case is small during the transition.The main frequency of transient hydraulic efficiency pulsation is equal to the blade frequency.At the main frequency,Z7 has the largest amplitude of the hydraulic efficiency pulsation,Z10 has the smallest amplitude,and the difference between Z7 and Z9 is limited.As the number of blades grows,the pressure pulsation during the transition process gradually decreases,but the pressure pulsation of Z10 at the volute tongue is larger.In the steady state,Z9 has the highest efficiency and in the transient stage,the pressure coefficientfluctuation range is small.Accordingly,for the hydraulic turbine Z9,the performance is optimal.

A Case of Esophageal Perforation Presenting as Cavitary Pneumonia: Diagnostic and Therapeutic Challenges

Esophageal perforation, a rare condition, can arise from iatrogenic, traumatic, or spontaneous origins. Even when therapy is initiated within the first 24 hours, it is associated with a mortality rate of up to 25%. Due to the varied initial presentation, treatment may be delayed, leading to poorer outcomes. Here, we present a unique case of a 27-year-old schizophrenic patient who initially presented with acute respiratory failure and septic shock and was ultimately diagnosed with cavitary pneumonia secondary to esophageal perforation.

Simple procedure for assessing diffuse subarachnoid hemorrhage successfully created using filament perforation method in mice

The murine model of subarachnoid hemorrhage(SAH)is a valuable experimental tool for investigating molecular and cellular mechanisms,and the endovascular filament perforation technique can be used to simulate prominent pathophysiological features observed after human SAH;however,current validation methods for assessing an appropriate SAH model are limited.Here,we introduce a simple procedure for se-lecting a mouse model of diffuse SAH.SAH was induced in 24 mice using a standard filament perforation method.After confirming survival at 24 h,SAH was scored 0-1 based on T2*-weighted images on whole-brain magnetic resonance imaging(MRI)and visual surveillance of the cisterna magna(CM)through the dura mater.The CM-based SAH grading correlated well with a reference parameter defined by extracted brain(r^(2)=0.53,p<0.0001).The receiver operating characteristic curve revealed a sensi-tivity of 85%and a specificity of 91%for detecting diffuse SAH,with a similar area under the curve(0.89±0.06[standard error of the mean])as the MRI-based grading(0.72±0.10,p=0.12).Our data suggest that confirming an SAH clot in the CM is a valuable way to select a clinically relevant diffuse SAH model that can be used in future experimental studies.

Pumping-induced Well Hydraulics and Groundwater Budget in a Leaky Aquifer System with Vertical Heterogeneity in Aquitard Hydraulic Properties

In groundwater hydrology,aquitard heterogeneity is often less considered compared to aquifers,despite its significant impact on groundwater hydraulics and groundwater resources evaluation.A semi-analytical solution is derived for pumping-induced well hydraulics and groundwater budget with consideration of vertical heterogeneity in aquitard hydraulic conductivity(K)and specific storage(S_(s)).The proposed new solution is innovative in its partitioning of the aquitard into multiple homogeneous sub-layers to enable consideration of various forms of vertically heterogeneous K or S_(s).Two scenarios of analytical investigations are explored:one is the presence of aquitard interlayers with distinct K or S_(s) values,a common field-scale occurrence;another is an exponentially depth-decaying aquitard S_(s),a regional-scale phenomenon supported by statistical analysis.Analytical investigations reveal that a low-K interlayer can significantly increase aquifer drawdown and enhance aquifer/aquitard depletion;a high-S_(s) interlayer can noticeably reduce aquifer drawdown and increase aquitard depletion.Locations of low-K or high-S_(s) interlayers also significantly impact well hydraulics and groundwater budget.In the context of an exponentially depth-decaying aquitard S_(s),a larger decay exponent can enhance aquifer drawdown.When using current models with a vertically homogeneous aquitard,half the sum of the geometric and harmonic means of exponentially depth-decaying aquitard S_(s) should be used to calculate aquitard depletion and unconfined aquifer leakage.

Experimental Investigation on Vertical Hydraulic Transport of Ores in Deepsea Mining

Deepsea mining has been proposed since the 1960s to alleviate the lack of resources on land.Vertical hydraulic transport of collected ores from the seabed to the sea surface is considered the most promising method for industrial applications.In the present study,an indoor model test of the vertical hydraulic transport of particles was conducted.A noncontact optical method has been proposed to measure the local characteristics of the particles inside a vertical pipe,including the local concentration and particle velocity.The hydraulic gradient of ore transport was evaluated with various particle size distributions,particle densities,feeding concentrations and mixture flow velocities.During transport,the local concentration is larger than the feeding concentration,whereas the particle velocity is less than the mixture velocity.The qualitative effects of the local concentration and local fluid velocity on the particle velocity and slip velocity were investigated.The local fluid velocity contributes significantly to particle velocity and slip velocity,whereas the effect of the local concentration is marginal.A higher feeding concentration and mixture flow velocity result in an increased hydraulic gradient.The effect of the particle size gradation is slight,whereas the particle density plays a crucial role in the transport.

The Evolutionary Profile of Patients Operated for Peptic Ulcer Perforation in Bujumbura

Background: The evolutionary profile of patients operated for peptic ulcer perforation in Bujumbura. Perforated peptic ulcer is a serious complication of peptic ulcer with potential risk of grave complications. Aim: To study the early morbidity and mortality of surgery for peptic ulcer perforation in Bujumbura City Hall hospitals: Kamenge University Hospital Center (CHUK), Kamenge Military Hospital (HMK) and Prince Louis Rwagasore Clinic (CPLR). Patients and methods: This is a retrospective, descriptive and analytical study carried out in the three hospitals of Bujumbura over a period of three years from January 1, 2020 to December 31, 2022. It involved 57 cases (n = 57) of peptic ulcer perforation. Results: The frequency of surgery for peptic ulcer perforation was 2.7% with a mean age of 43.6 years +/- 15.3 years and a male predominance with a sex ratio of 3.7. Eight percent of patients presented with shock, 24.5% were smokers, and 67.9% had taken non steroidal anti-inflammatory drugs. The mean hospital stay was 15.2 days with a standard deviation of 12.1. The morbidity rate was 30.2%, 32% were classified in grade IIIb of the Clavien-Dindo Surgical Complications Scale. There were 9 deaths (17%). Seven patients who underwent surgery and received late consultations died. Conclusion: Surgery for peptic ulcer perforation remains an intervention associated with a high rate of morbidity and mortality in Bujumbura. Surgery for peptic ulcer perforation remains a procedure associated with a high morbidity and mortality rate in Bujumbura. The time before consultation was the only factor associated with early morbidity and mortality of Surgery for peptic ulcer’s perforations.

Previously undiagnosed Morgagni hernia with bowel perforation detected during repeat screening colonoscopy: A case report

BACKGROUND Morgagni hernia(MH)is a form of congenital diaphragmatic hernia(CDH)characterized by an incomplete formation of diaphragm,resulting in the protru-sion of abdominal organs into the thoracic cavity.The estimated incidence of CDH is between 1 in 2000 and 1 in 5000 live births,although the true incidence is unknown.MH typically presents in childhood and can be diagnosed either pre-natally or postnatally.However,it can also be asymptomatic and carry the risk of developing into a life-threatening condition in adulthood.CASE SUMMARY A 76-year-old female with no history of prior abdominal surgeries presented for an elective colonoscopy for polyp surveillance.During the procedure,when approaching the hepatic flexure,the scope could not be advanced further despite multiple attempts.The patient experienced mild abdominal discomfort,leading to the abortion of the procedure.While in the recovery area,she developed increa-sing abdominal pains and hypotension.Urgent abdominal imaging revealed her-niation of the proximal transverse colon through a MH into the chest with evi-dence of perforation.The patient underwent laparoscopic urgent colonic resection and primary hernia repair and was discharged uneventfully 2 d later.CONCLUSION A MH is a rare condition in adults that can present as a life-threatening compli-cation of colonoscopy,even in patients with a history of uneventful colonoscopies.This case highlights the importance of considering congenital and internal hernias when faced with sudden and unexplained difficulties during colonoscopy.If there is a suspicion of MH,the endoscopist should halt the procedure and immediately obtain abdominal imaging to confirm the diagnosis.

Vomiting-induced pharyngeal perforation during bowel preparation for colonoscopy:A case report

BACKGROUND Effective bowel cleansing is essential for a successful colonoscopy.Laxatives,such as polyethylene glycol,are commonly used for bowel preparation.Vomiting is a frequent complication during bowel preparation,and forceful vomiting can potentially lead to esophageal perforation,as reported in several previous cases.However,pharyngeal perforation during bowel preparation has not been previously documented.Here,we present a case of pharyngeal perforation induced by forceful vomiting during bowel preparation.CASE SUMMARY A 38-year-old man with a history of hypertension,dyslipidemia,diabetes mellitus,and end-stage renal disease on hemodialysis was admitted for evaluation of recurrent abdominal pain.The patient complained of sudden pain in the neck,throat,and anterior chest following forceful vomiting during bowel preparation.Physical examination revealed crepitus under the skin of the neck and anterior chest on palpation,and upper gastrointestinal endoscopy revealed pharyngeal perforation.The perforation site was located above the upper esophageal sphincter,which distinguished it from Boerhaave’s syndrome.Conservative medical management was chosen after consultation with a thoracic surgeon and an otolaryngologist,considering the patient's mild symptoms,stable vital signs,and the small size of the lesion;the perforation resolved without endoscopic or surgical intervention.The patient was discharged from hospital two weeks after the perforation.CONCLUSION Despite its rarity,pharyngeal perforation should be considered a potential complication of bowel preparation for colonoscopy.

Small intestine angioleiomyoma as a rare cause of perforation:A case report

BACKGROUND Angioleiomyoma is a rare and benign stromal tumor typically found in subcutaneous tissue.It rarely occurs in the gastrointestinal tract.Among the reported cases,the most common complication was gastrointestinal bleeding.Perforation has only been reported as a complication in the last few decades.CASE SUMMARY This case report detailed the discovery of intestinal angioleiomyoma in a 47-yearold male presenting with abdominal pain that had persisted for 3 d.After suspecting hollow organ perforation,surgical intervention involving intestinal resection and anastomosis was performed.CONCLUSION The report underscores the significance of early surgical intervention in effectively treating angioleiomyoma while emphasizing the pivotal role of timely and appropriate measures for favorable outcomes.

Clinical Epidemiology and Surgical Treatment of Spontaneous Perforations of the Terminal Ileum: A Multicentre Study in Cameroon

Background: Perforations of the terminal ileum are a frequent clinical situation and a therapeutic challenge. Surgical treatment is controversial. Several surgical modalities have been proposed and postoperative morbidity and mortality remain high. The aim of this study was to review our experience in the surgical management of perforations of the terminal ileum. Patients and methods: This is a descriptive cross-sectional study with retrospective data collection from January 1, 2017 to December 31, 2021, in five hospitals in Cameroon. Patients’ demographic, clinical presentation, surgical findings and 30-days postoperative outcomes data were collected. Results: We collected 34 files. The sex ratio was 1.4 and the average age was 20.28 years. The average consultation time was 9.1 days. Abdominal pain was present in all our patients. Peritoneal irritation was present in 46 cases (88.5%). The mean time to treatment after admission was 17.5 hours. The perforation was unique in 40 cases (76.9%) and located between 6 and 10 cm from the ileocecal valve in 29 cases (55.8%). Typhoid was the most suspected etiology intraoperatively in 38 cases (73.1%). A simple suture was performed in 18 patients (34.6%), resection with anastomosis in 11 patients (21.2%) and an ileostomy in 5 patients (9.6%). The average length of hospitalization was 21.74 days. Postoperative morbidity and mortality were 32.7% and 17.3% respectively. Conclusion: Perforations of the terminal ileum are common and affect young people. Surgical procedures are varied. Reducing consultation and care times and respecting treatment principles could improve postoperative morbidity and mortality, which remain high.

Efficacy of Cyanoacrylate Tissue Adhesive Application in the Management of Corneal Perforations at Preah Ang Duong Hospital in Cambodia

Purpose: The study was to evaluate the efficacy of cyanoacrylate tissue adhesive (CTA) application in corneal perforations. Method: This was a prospective study on 20 patients of corneal perforations who received cyanoacrylate tissue adhesive application as treatment between March 2021 and March 2022 at Preah Ang Duong Hospital. The primary outcome measure was success rate of CTA application, while the secondary outcome was to measure postoperative best-corrected visual acuity (BCVA) and ocular complications. Results: The mean age of patients was 44.15 ± 16.05 years old and 7 (35%) were female. Causes of perforation were microbial infection in 12 patients (60%), trauma in 5 patients (25%), and sterile melting in 3 patients (15%). The perforation of size smaller than 1.5 mm was in 8 patients (40%) while 12 patients (60%) had perforated size between 1.5 mm to 3 mm. The perforation was 60% (12 patients) central, 25% (5 patients) paracentral, and 15% (3 patients) peripherally. Out of 20 patients, 5 patients (25%) received CTA application more than 1 time. The mean glue retention was 57.60 ± 31.84 days. Success rate of glue application (defined as intact globe without surgical intervention regardless of number of CTA applications) was 85%. At the last visit, 7 patients (35%) had BCVA of 6/120 or better. Common complications were uveitis (45%), ocular hypertension (30%), cataract (25%) and neovascularization (20%). No serious complications were found. Conclusion: Cyanoacrylate tissue adhesive is an effective treatment option in sealing corneal perforations with no serious complications. .

Effect of perforation density distribution on production of perforated horizontal wellbore

To address the issue of horizontal well production affected by the distribution of perforation density in the wellbore,a numerical model for simulating two-phase flow in a horizontal well is established under two perforation density distribution conditions(i.e.increasing the perforation density at inlet and outlet sections respectively).The simulation results are compared with experimental results to verify the reliability of the numerical simulation method.The behaviors of the total pressure drop,superficial velocity of air-water two-phase flow,void fraction,liquid film thickness,air production and liquid production that occur with various flow patterns are investigated under two perforation density distribution conditions based on the numerical model.The total pressure drop,superficial velocity of the mixture and void fraction increase with the air flow rate when the water flow rate is constant.The liquid film thickness decreases when the air flow rate increases.The liquid and air productions increase when the perforation density increases at the inlet section compared with increasing the perforation density at the outlet section of the perforated horizontal wellbore.It is noted that the air production increases with the air flow rate.Liquid production increases with the bubble flow and begins to decrease at the transition point of the slug-stratified flow,then increases through the stratified wave flow.The normalized liquid flux is higher when the perforation density increases at the inlet section,and increases with the radial air flow rate.

Multistage hydraulic fracturing of a horizontal well for hard roof related coal burst control:Insights from numerical modelling to field application

Multistage hydraulic fracturing of horizontal wells(MFHW)is a promising technology for controlling coal burst caused by thick and hard roofs in China.However,challenges remain regarding the MFHW control mechanism of coal burst and assessment of the associated fracturing effects.In this study,these challenges were investigated through numerical modelling and field applications,based on the actual operating parameters of MFHW for hard roofs in a Chinese coal mine.A damage parameter(D)is proposed to assess the degree of hydraulic fracturing in the roof.The mechanisms and effects of MFHW for controlling coal burst are analyzed using microseismic(MS)data and front-abutment stress distribution.Results show that the degree of fracturing can be categorized into lightly-fractured(D≤0.3),moderately fractured(0.3<D≤0.6),well-fractured(0.6<D≤0.9),and over-fractured(0.9<D≤0.95).A response stage in the fracturing process,characterized by a slowdown in crack development,indicates the transition to a wellfractured condition.After MFHW,the zone range and peak value of the front-abutment stress decrease.Additionally,MS events shift from near the coal seam to the fractured roof layers,with the number of MS events increases while the average MS energy decreases.The MFHW control mechanisms of coal bursts involve mitigating mining-induced stress and reducing seismic activity during longwall retreat,ensuring stresses remain below the ultimate stress level.These findings provide a reference for evaluating MFHW fracturing effects and controlling coal burst disasters in engineering.

Formation and rupture of liver hematomas caused by intrahepatic gallbladder perforation:A case report and review of literature

BACKGROUND Gallbladder perforation is a serious complication of acute cholecystitis.Such perforation is a rare but life-threatening situation that can lead to the formation and rupture of liver hematomas.Here,we report a case of a ruptured intrahepatic hematoma caused by intrahepatic gallbladder perforation,and we present a literature review.CASE SUMMARY A 70-year-old male was admitted to the hospital with a complaint of right upper quadrant abdominal pain,flustering and dizziness.The preoperative diagnosis was a ruptured malignant liver tumor,and the patient’s medical images and increased level of carbohydrate antigen-199 suggested that the gallbladder had been invaded.However,the tumor was proven to be a liver hematoma secondary to gallbladder perforation after surgery.The patient was discharged uneventfully on the fifteenth postoperative day.CONCLUSION Intrahepatic gallbladder perforation is difficult to diagnose preoperatively.Radiological examinations play a crucial role in the diagnosis but only for partial cases.Early diagnosis and appropriate surgery are key to managing this rare condition.

Physical and numerical investigations of target stratum selection for ground hydraulic fracturing of multiple hard roofs

Ground hydraulic fracturing plays a crucial role in controlling the far-field hard roof,making it imperative to identify the most suitable target stratum for effective control.Physical experiments are conducted based on engineering properties to simulate the gradual collapse of the roof during longwall top coal caving(LTCC).A numerical model is established using the material point method(MPM)and the strain-softening damage constitutive model according to the structure of the physical model.Numerical simulations are conducted to analyze the LTCC process under different hard roofs for ground hydraulic fracturing.The results show that ground hydraulic fracturing releases the energy and stress of the target stratum,resulting in a substantial lag in the fracturing of the overburden before collapse occurs in the hydraulic fracturing stratum.Ground hydraulic fracturing of a low hard roof reduces the lag effect of hydraulic fractures,dissipates the energy consumed by the fracture of the hard roof,and reduces the abutment stress.Therefore,it is advisable to prioritize the selection of the lower hard roof as the target stratum.

Colon perforation with severe peritonitis caused by erotic toy insertion and treated using vacuum-assisted closure:A case report

BACKGROUND Colorectal foreign bodies are commonly encountered during surgery.They are frequently observed in men 20 to 90 years of age and have bimodal age distribution.Surgical management is necessary for cases of rectal perforation.However,surgical site infections are the most common complications after colorectal surgery.CASE SUMMARY We discuss a case of rectal perforation in a patient who presented to our hospital 2 d after its occurrence.The perforation occurred as a result of the patient inserting a sex toy in his rectum.Severe peritonitis was attributable to delayed presentation.CONCLUSION Vacuum-assisted closure was performed to treat the wound,which healed well after therapy.No complications were noted.

Vertical distribution characteristics of soil saturated hydraulic conductivity under different land use patterns in the Mu Us sandy land

Background,aim,and scope Soil saturated hydraulic conductivity(K_(s))is a key parameter in the hydrological cycle of soil;however,we have very limited understanding of K_(s) characteristics and the factors that inf luence this key parameter in the Mu Us sandy land(MUSL).Quantifying the impact of changes in land use in the Mu Us sandy land on K_(s) will provide a key foundation for understanding the regional water cycle,but will also provide a scientific basis for the governance of the MUSL.Materials and methods In this study,we determined K_(s) and the basic physical and chemical properties of soil(i.e.,organic matter,bulk density,and soil particle composition)within the first 100 cm layer of four different land use patterns(farmland,tree,shrub,and grassland)in the MUSL.The vertical variation of K_(s) and the factors that influence this key parameter were analyzed and a transfer function for estimating K_(s) was established based on a multiple stepwise regression model.Results The K_(s) of farmland,tree,and shrub increased gradually with soil depth while that of grassland remained unchanged.The K_(s) of the four patterns of land use were moderately variable;mean K_(s)values were ranked as follows:grassland(1.38 mm·min^(-1))<tree(1.76 mm·min^(-1))<farmland(1.82 mm·min^(-1))<shrub(3.30 mm·min^(-1)).The correlation between K_(s) and organic matter,bulk density,and soil particle composition,varied across different land use patterns.A multiple stepwise regression model showed that silt,coarse sand,bulk density,and organic matter,were key predictive factors for the K_(s) of farmland,tree,shrub,and grassland,in the MUSL.Discussion The vertical distribution trend for K_(s) in farmland is known to be predominantly influenced by cultivation,fertilization,and other factors.The general aim is to improve the water-holding capacity of shallow soil on farmland(0-30 cm in depth)to conserve water and nutrients;research has shown that the K_(s) of farmland increases with soil depth.The root growth of tree and shrub in sandy land exerts mechanical force on the soil due to biophysical processes involving rhizospheres,thus leading to a significant change in K_(s).We found that shallow high-density fine roots increased the volume of soil pores and eliminated large pores,thus resulting in a reduction in shallow K_(s).Therefore,the K_(s) of tree and shrub increased with soil depth.Analysis also showed that the K_(s) of grassland did not change significantly and exhibited the lowest mean value when compared to other land use patterns.This finding was predominantly due to the shallow root system of grasslands and because this land use pattern is not subject to human activities such as cultivation and fertilization;consequently,there was no significant change in K_(s) with depth;grassland also had the lowest mean K_(s).We also established a transfer function for K_(s) for different land use patterns in the MUSL.However,the predictive factors for K_(s) in different land use patterns are known to be affected by soil cultivation methods,vegetation restoration modes,the distribution of soil moisture,and other factors,thus resulting in key differences.Therefore,when using the transfer function to predict K_(s) in other areas,it will be necessary to perform parameter calibration and further verification.Conclusions In the MUSL,the K_(s) of farmland,tree,and shrub gradually increased with soil depth;however,the K_(s) of grassland showed no significant variation in terms of vertical distribution.The mean K_(s) values of different land use patterns were ranked as follows:shrub>farmland>tree>grassland;all land use patterns showed moderate levels of variability.The K_(s) for different land use patterns exhibited differing degrees of correlation with soil physical and chemical properties;of these,clay,silt,sand,bulk density,and organic matter,were identified as important variables for predicting K_(s) in farmland,tree,shrub,and grassland,respectively.Recommendations and perspectives In this study,we used a stepwise multiple regression model to establish a transfer function prediction model for K_(s) for different land use patterns;this model possessed high estimation accuracy.The ability to predict K_(s) in the MUSL is very important in terms of the conservation of water and nutrients.