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.

Productivity Prediction Model of Perforated Horizontal Well Based on Permeability Calculation in Near-Well High Permeability Reservoir Area

To improve the productivity of oil wells,perforation technology is usually used to improve the productivity of horizontal wells in oilfield exploitation.After the perforation operation,the perforation channel around the wellbore will form a near-well high-permeability reservoir area with the penetration depth as the radius,that is,the formation has different permeability characteristics with the perforation depth as the dividing line.Generally,the permeability is measured by the permeability tester,but this approach has a high workload and limited application.In this paper,according to the reservoir characteristics of perforated horizontal wells,the reservoir is divided into two areas:the original reservoir area and the near-well high permeability reservoir area.Based on the theory of seepage mechanics and the formula of open hole productivity,the permeability calculation formula of near-well high permeability reservoir area with perforation parameters is deduced.According to the principle of seepage continuity,the seepage is regarded as the synthesis of two directions:the horizontal plane elliptic seepage field and the vertical plane radial seepage field,and the oil well productivity prediction model of the perforated horizontal well is established by partition.The model comparison demonstrates that the model is reasonable and feasible.To calculate and analyze the effect of oil well production and the law of influencing factors,actual production data of the oilfield are substituted into the oil well productivity formula.It can effectively guide the technical process design and effect prediction of perforated horizontal wells.

Perforated gastric ulcer causing mediastinal emphysema: A case report

BACKGROUND Mediastinal emphysema is a condition in which air enters the mediastinum between the connective tissue spaces within the pleura for a variety of reasons.It can be spontaneous or secondary to chest trauma,esophageal perforation,medi-cally induced factors,etc.Its common symptoms are chest pain,tightness in the chest,and respiratory distress.Most mediastinal emphysema patients have mild symptoms,but severe mediastinal emphysema can cause respiratory and circulatory failure,resulting in serious consequences.CASE SUMMARY A 75-year-old man,living alone,presented with sudden onset of severe epigastric pain with chest tightness after drinking alcohol.Due to the remoteness of his residence and lack of neighbors,the patient was found by his nephew and brought to the hospital the next morning after the disease onset.Computed tomography(CT)showed free gas in the abdominal cavity,mediastinal emph-ysema,and subcutaneous pneumothorax.Upper gastrointestinal angiography showed that the esophageal mucosa was intact and the gastric antrum was perforated.Therefore,we chose to perform open gastric perforation repair on the patient under thoracic epidural anesthesia combined with intravenous anesthesia.An operative incision of the muscle layer of the patient's abdominal wall was made,and a large amount of subperitoneal gas was revealed.And a continued incision of the peritoneum revealed the presence of a perforation of approx-imately 0.5 cm in the gastric antrum,which we repaired after pathological examination.Postoperatively,the patient received high-flow oxygen and cough exercises.Chest CT was performed on the first and sixth postoperative days,and the mediastinal and subcutaneous gas was gradually reduced.CONCLUSION After gastric perforation,a large amount of free gas in the abdominal cavity can reach the mediastinum through the loose connective tissue at the esophageal hiatus of the diaphragm,and upper gastrointestinal angiography can clarify the site of perforation.In patients with mediastinal emphysema,open surgery avoids the elevation of the diaphragm caused by pneumoperitoneum compared to laparoscopic surgery and avoids increasing the mediastinal pressure.In addition,thoracic epidural anesthesia combined with intravenous anesthesia also avoids pressure on the mediastinum from mechanical ventilation.

Numerical Analysis of Residual Strength in the Perforated Casing of Ultra Deep Wells

A three-dimensional model for the numerical simulation of casing-cement behavior is used to investigate residual strength in the perforated casing of ultra deep wells.The influence of the hole diameter,hole density and phase angle on the residual strength of the casing under non-uniform stress and fracturing conditions is revealed through the consideration of different perforation parameters.It is shown that the residual strength of the casing increases with the hole diameter and periodically changes with the hole density;the phase angle is the main factor that affects the residual strength of the perforated casing,and the perforation should be avoided in the direction of the minimum principal stress to reduce stress concentration at the perforation hole.Moreover,as shown by a companion orthogonal experiment,the descending order of influence of the different influential parameters is:phase angle,hole diameter,hole density and the thickness of casing.

Analytical and Experimental Research on Wave Scattering by an Open-Type Rectangular Breakwater with Horizontal Perforated Plates

This study proposes a novel open-type rectangular breakwater combined with horizontal perforated plates on both sides to enhance the sheltering effect of the rectangular box-type breakwaters against longer waves.The hydrodynamic characteristics of this breakwater are analyzed through analytical potential solutions and experimental tests.The quadratic pressure drop conditions are exerted on the horizontal perforated plates to facilitate assessing the effect of wave height on the dissipated wave energy of breakwater through the analytical solution.The hydrodynamic quantities of the breakwater,including the reflection,transmission,and energyloss coefficients,together with vertical and horizontal wave forces,are calculated using the velocity potential decomposition method as well as an iterative algorithm.Furthermore,the reflection and transmission coefficients of the breakwater are measured by conducting experimental tests at various wave periods,wave heights,and both porosities and widths of the horizontal perforated plates.The analytical predicted results demonstrate good agreement with the iterative boundary element method solution and measured data.The influences of variable incident waves and structure parameters on the hydrodynamic characteristics of the breakwater are investigated through further calculations based on analytical solutions.Results indicate that horizontal perforated plates placed on the water surface for both sides of the rectangular breakwater can enhance the wave dissipation ability of the breakwater while effectively decreasing the transmission and reflection coefficients.

Optimizing the Diameter of Plugging Balls in Deep Shale Gas Wells

Deep shale gas reserves that have been fractured typically have many relatively close perforation holes. Due to theproximity of each fracture during the formation of the fracture network, there is significant stress interference,which results in uneven fracture propagation. It is common practice to use “balls” to temporarily plug fractureopenings in order to lessen liquid intake and achieve uniform propagation in each cluster. In this study, a diameteroptimization model is introduced for these plugging balls based on a multi-cluster fracture propagationmodel and a perforation dynamic abrasion model. This approach relies on proper consideration of the multiphasenature of the considered problem and the interaction force between the involved fluid and solid phases. Accordingly,it can take into account the behavior of the gradually changing hole diameter due to proppant continuousperforation erosion. Moreover, it can provide useful information about the fluid-dynamic behavior of the consideredsystem before and after plugging. It is shown that when the diameter of the temporary plugging ball is1.2 times that of the perforation hole, the perforation holes of each cluster can be effectively blocked.

Fracture propagation law of temporary plugging and diversion fracturing in shale reservoirs under completion experiments of horizontal well with multi-cluster sand jetting perforation

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.

Mediastinal emphysema in the context of perforated gastric ulcer

In the context of mediastinal emphysema/pneumomediastinum,the main aetiologies are associated with oesophageal perforation,lung pathology or post head and neck surgery related.The main way to differentiate the pathologies would be through Computed Tomographic Imaging of the Thorax and abdomen with oral and intravenous contrast in the context of triple phase imaging.The causes of pneumomediastinum should be differentiated between traumatic and non-traumatic.Oesophageal perforation(Boerhaave syndrome)is associated with Mackler’s triad in upto 50%of patients(severe retrosternal chest pain,pneumomediastinum,mediastinitis).Whereas in cases of lung pathology this can be associated with pneumothorax and pleural effusion.

Balloon dilation of congenital perforated duodenal web in newborns: Evaluation of short and long-term results

BACKGROUND Incomplete congenital duodenal obstruction(ICDO)is caused by a congenitally perforated duodenal web(CPDW).Currently,only six cases of balloon dilatation of the PDW in newborns have been described.AIM To present our experience of balloon dilatation of a perforated duodenal memb-rane in newborns with ICDO.METHODS Five newborns who underwent balloon dilatation of the CPDW along a prein-stalled guidewire between 2021 and 2023 were included.Nineteen newborns diagnosed with ICDO who underwent laparotomy were included in the control group.RESULTS In all cases,good anatomical and clinical results were obtained.In three cases,a follow-up study was conducted after 1 year.The average time to start enteral feeding per os was significantly earlier in the study group(4.4 d)than in the laparotomic group(21.2 days;P<0.0001).The time spent by patients in the intensive care unit and hospital after balloon dilatation was also significantly shorter.We determined the selection criteria for possible and effective CPDW balloon dilatation in newborns as follows:(1)Presence of dynamic radiographic signs of the passage of a radiopaque substance beyond the zone of narrowing or radiographic signs of pneumatisation of the duodenum and small bowel distal to the web;(2)presence of endoscopic signs of CPDW;(3)successful cannulation with a guidewire performed parallel to the endoscope,with holes in the congenital duodenal web;and(4)successful positioning of the balloon performed along a freestanding guidewire on the web.CONCLUSION Strictly following selection criteria for newborns with ICDO caused by CPDW ensures that endoscopic balloon dilatation using a pre-installed guidewire is safe and effective and shows good 1-year follow-up results.

Surgical Management of Perforated Colon Tumours in Yaoundé: A Multicentre Retrospective Review of 30-Day Postoperative Outcome

Introduction: Colon cancer is often diagnosed late in our context and there is a high prevalence of complicated forms, this including perforation. The optimal surgical treatment remains controversial. The aim of this study was to improve the short-term postoperative outcomes of patients operated upon for perforated colon cancer, by identifying factors associated with complications occurring within 30 days after surgery. Patients and methods: We carried out an analytical observational study, with a retrospective collection of data from the files of patients operated upon for an in situ tumoral colon perforation. This was done in four referral hospitals in the city of Yaoundé. The period was from the 1st of January, 2012 to the 31st of December, 2021. Cox regression identified the factors associated with postoperative morbidity and mortality. Results: We collected files of 46 patients. The mean age was 54.7 ± 19.9 years with a sex ratio of 1.4. The clinical presentation on admission was dominated by the presence of signs of peritoneal irritation (91.3%) and bowel obstruction (28.3%). The diagnosis was made preoperatively in 16 cases (34.8%). The surgical procedures consisted of colectomy with anastomosis in 28 cases (60.9%) and without anastomosis in 14 cases (30.4%). Postoperative morbidity was 60.9% dominated by surgical site infection (37%). Postoperative mortality was 39.1%. The existence of generalized peritonitis was associated with the occurrence of postoperative complications (p = 0.019). The main factors associated with postoperative mortality were resection with primary anastomosis (p = 0.027), enterocutaneous fistula (p = 0.005). Conclusion: Colic resection with primary anastomosis or ideal colectomy is associated with an increased risk of mortality and should therefore not be performed in this setting.

Correlation of serum albumin level on postoperative day 2 with hospital length of stay in patients undergoing emergency surgery for perforated peptic ulcer

BACKGROUND Perforated peptic ulcer(PPU)is a common emergency surgical condition and a significant cause of morbidity and mortality worldwide.While advances in surgical techniques have improved outcomes for patients with PPU,many factors still affect postoperative hospital stay and overall prognosis.One potential factor is the serum albumin(SA)level,a widely utilized marker of nutritional status that has been associated with length of stay and complications in various surgical procedures.AIM To clarify the correlation of SA level on postoperative day 2 with hospital length of stay(HLOS)in patients undergoing emergency surgery for perforated peptic ulcer(PPU).METHODS We retrospectively collected and analyzed clinical baseline data,including blood routine and SA levels,of patients who underwent emergency PPU surgery and postoperative treatment at the Lingnan Hospital,the Third Affiliated Hospital of Sun Yat-sen University between December 2012 and September 2021.Patients were grouped according to HLOS with 7 d as the cut-off value,and relevant indicators were analyzed using SPSS 26.0.RESULTS Of the 37 patients undergoing emergency surgery for PPU referred to our department,33 had gastric and 4 had duodenal ulcer perforation.The median HLOS was 10 d.There were 8 patients in the≤7-d group(median HLOS:7 d)and 29 patients in the>7-d group(median HLOS:10 d).The≤7-d group had markedly higher SA on postoperative day 2 than the>7-d group(37.7 g/L vs 32.6g/L;P<0.05).The SA level on postoperative day 2 was a protective factor for patients with HLOS>7 d(Odds ratio=0.629,P=0.015).The cut-off of SA on postoperative day 2 was 30.6g/L,with an area under the curve of 0.86 and a negative predictive value of 100%for the prediction of HLOS≤7 d.CONCLUSION The SA level on postoperative day 2 was associated with the HLOS in patients undergoing emergency surgery for PPU.The pre-and post-operative albumin levels should be monitored,and infusion of human SA should be considered in a timely manner.

Blast disruption using 3D grids/perforated plates for vehicle protection

In this work, blast disruption and mitigation using 3D grids/perforated plates were tested for underbelly and side protection of vehicles. Two vehicle simulants were used: a small-scale one for side vehicle protection assessment and a true-to-scale simulant for underbelly protection testing. The deformation of target plates was assessed. These were either unprotected or protected by three different types of disruptors. The first disruptor was made of a sandwich structure of two perforated plates filled with a thin aluminum structure allowing the air to pass through. The two other disruptors were made of pieces of cast metallic foam. Two different kinds of foams were used: one with large cells and the second one with small cells. Beforehand, the mitigation efficiency of the disruptors was evaluated using an explosivedriven shock tube(EDST). The experiments showed that blast disruption/mitigation by 3D grid/perforated plate structures was not suitable for vehicle side protection. However, 3D grids/perforated structures proved to be relatively effective for underbelly protection compared to an equivalent mass of steel.

Calculation and Analysis of Acoustic Characteristics of Straight-Through Perforated Pipe Muffler Based on Multilayer Sound Absorbing Material

Using the multi-physical field simulation software COMSOL,the acoustic characteristics of the multilayer sound absorbing material straight-through perforated pipe muffler are studied by the finite element method.The results show that the finite element calculation of the multilayer sound absorbing material straight-through the perforated pipe muffler agrees well with the experimental measurement results.The reliability of the finite element method for studying the acoustic performance of the straight-through perforated pipe muffler with multilayer sound absorbing materials is shown.Furthermore,the influence of some structural parameters of porous sound absorbing material and micro-perforated plate on the acoustic performance of the multilayer sound absorbing material straight-through perforated pipe muffler is analyzed.The muffler based on multilayer sound absorbing material is different from the traditional muffler.After applying the multilayer sound absorbing material to the straight-through perforated pipe muffler,the transmission loss value greatly increases,which provides new ideas and directions for future research on the muffler.

The influences of perforating phase and bedding planes on the fracture deflection in laminated shale

The perforating phase leads to complex and diverse hydraulic fracture propagation behaviors in laminated shale formations. In this paper, a 2D high-speed imaging scheme which can capture the interaction between perforating phase and natural shale bedding planes was proposed. The phase field method was used to simulate the same conditions as in the experiment for verification and hydraulic fracture propagation mechanism under the competition of perforating phase and bedding planes was discussed.The results indicate that the bedding planes appear to be no influence on fracture propagation while the perforating phase is perpendicular to the bedding planes, and the fracture propagates along the perforating phase without deflection. When the perforating phase algins with the bedding planes, the fracture initiation pressure reserves the lowest value, and no deflection occurs during fracture propagation. When the perforating phase is the angle 45°, 60°and 75°of bedding planes, the bedding planes begin to play a key role on the fracture deflection. The maximum deflection degree is reached at the perforating phase of75°. Numerical simulation provides evidence that the existence of shale bedding planes is not exactly equivalent to anisotropy for fracture propagation and the difference of mechanical properties between different shale layers is the fundamental reason for fracture deflection. The findings help to understand the intrinsic characteristics of shale and provide a theoretical basis for the optimization design of field perforation parameters.

Research on the Generation Mechanism and Suppression Method of Aerodynamic Noise in Expansion Cavity Based on Hybrid Method

The expansion chamber serves as the primary silencing structure within the exhaust pipeline.However,it can also act as a sound-emitting structure when subjected to airflow.This article presents a hybrid method for numerically simulating and analyzing the unsteady flow and aerodynamic noise in an expansion chamber under the influence of airflow.A fluid simulation model is established,utilizing the Large Eddy Simulation(LES)method to calculate the unsteady flow within the expansion chamber.The simulation results effectively capture the development and changes of the unsteady flow and vorticity inside the cavity,exhibiting a high level of consistency with experimental observations.To calculate the aerodynamic noise sources within the cavity,the flow field results are integrated using the method of integral interpolation and inserted into the acoustic grid.The acoustic analogy method is then employed to determine the aerodynamic noise sources.An acoustic simulation model is established,and the flow noise source is imported into the sound field grid to calculate the sound pressure at the far-field response point.The calculated sound pressure levels and resonance frequencies show good agreement with the experimental results.To address the issue of airflow regeneration noise within the cavity,perforated tubes are selected as a means of noise suppression.An experimental platformfor airflow regeneration noise is constructed,and experimental samples are processed to analyze and verify the noise suppression effect of perforated tube expansion cavities under different airflow velocities.The research findings indicate that the perforated tube expansion cavity can effectively suppress low-frequency aerodynamic noise within the cavity by impeding the formation of strong shear layers.Moreover,the semi-perforated tube expansion cavity demonstrates the most effective suppression of aerodynamic noise.

Scattering of Water Waves by Dual Symmetric Inclined Floating Porous Barriers Using the DBEM

The scattering of normally incident water waves by two surface-piercing inclined perforated barriers in water with a uniform finite depth is investigated within the framework of linear water wave theory.Considering that thin barriers are zero-thickness,a novel numerical method involving the the coupling of the dual boundary element method(DBEM)with damping layers is applied.In order to effectively damp out the reflected waves,two damping layers,instead of pseudoboundaries are implemented near the two side boundaries of the computational domain.Thus,the modified linearized free surface boundary conditions are formulated and used for solving both the ordinary boundary integral equation as well as the hypersingular boundary integral equation for degenerate boundaries.The newly developed numerical method is validated against analytical methods using the matched eigenfunction expansion method for the special case of two vertical barriers or the inclined angle to the vertical being zero.The influence of the length of the two damping layers has been discussed.Moreover,these findings are also validated against previous results for several cases.After validation,the numerical results for the reflection coefficient,transmission coefficient and dissipation coefficient are obtained by varying the inclination angle and porosity-effect parameter.The effects of both the inclination angle and the porosity on the amplitudes of wave forces acting on both the front and rear barriers are also investigated.It is found that the effect of the inclination angle mainly shifts the location of the extremal values of the reflection and the transmission coefficients.Additionally,a moderate value of the porosity-parameter is quite effective at dissipating wave energy and mitigating the wave loads on dual barriers.

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.

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.

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.

Double-nylon purse-string suture technique: Another addition to the endoscopist's toolbox for full-thickness defect closure

Iatrogenic perforation is the most feared adverse event in endoscopy.With the expansion of interventional endoscopy in favor of traditional surgery,it is now more crucial than ever to develop effective defect closure techniques.This has culminated in the dissemination of multiple novel closure technologies,including through-the-scope clips,over-the-scope clips,through-the-scope suturing and over-the-scope suturing devices.In this editorial,we comment on the recent publication by Wang and colleagues discussing the performance of the double-nylon purse-string suture technique in the closure of large(>3 cm)gastric full-thickness defects.This technique offers a promising,practical and cost-effective approach to closure of large full-thickness defects that can be readily imple-mented across diverse healthcare settings.