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.

Dissolvable temporary barrier:a novel paradigm for flexible hydrogel patterning in organ-on-a-chip models

A combination of hydrogels and microfluidics allows the construction of biomimetic three-dimensional(3D)tissue models in vitro,which are also known as organ-on-a-chipmodels.The hydrogel patterningwith awell-controlled spatial distribution is typically achieved by embedding sophisticated microstructures to act as a boundary.However,these physical barriers inevitably expose cells/tissues to a less physiologically relevant microenvironment than in vivo conditions.Herein,we present a novel dissolvable temporary barrier(DTB)strategy that allows robust and flexible hydrogel patterning with great freedom of design and desirable flow stimuli for cellular hydrogels.The key aspect of this approach is the patterning of a water-soluble rigid barrier as a guiding path for the hydrogel using stencil printing technology,followed by a barrier-free medium perfusion after the dissolution of the DTB.Single and multiple tissue compartments with different geometries can be established using either straight or curved DTB structures.The effectiveness of this strategy is further validated by generating a 3D vascular network through vasculogenesis and angiogenesis using a vascularized microtumor model.As a new proof-of-concept in vasculature-on-a-chip,DTB enables seamless contact between the hydrogel and the culture medium in closed microdevices,which is an improved protocol for the fabrication ofmultiorgan chips.Therefore,we expect it to serve as a promising paradigm for organ-on-a-chip devices for the development of tumor vascularization and drug evaluation in the future preclinical studies.

HVOF-sprayed HAp/S53P4 BG composite coatings on an AZ31 alloy for potential applications in temporary implants

Bioactive thermal spray coatings produced via high-velocity oxygen fuel spray(HVOF)from hydroxyapatite(HAp)and bioactive glasses(BG)have the potential to be employed on temporary implants due to the ability of both HAp and BG to dissolve and promote osseointegration,considering that both phases have different reaction and dissolution rates under in-vitro conditions.In the present work,75%wt.HAp-25%wt.S53P4 bioactive glass powders were HVOF-sprayed to obtain HAp/S53P4 BG composite coatings on a bioresorbable AZ31 alloy.The study is focused on exploring the effect of the stand-off distance and fuel/oxygen ratio variation as HVOF parameters to obtain stable structural coatings and to establish their effect on the phases and microstructure produced in those coatings.Different characterization techniques,such as scanning electron microscopy,X-ray diffraction,and Fourier transform infrared spectroscopy,were employed to characterize relevant structural and microstructural properties of the composite coatings.The results showed that thermal gradients during coating deposition must be managed to avoid delamination due to the high temperature achieved(max 550℃)and the differences in coefficients of thermal expansion.It was also found that both spraying distance and oxygen/fuel ratio allowed to keep the hydroxyapatite as the main phase in the coatings.In addition,in-vitro electrochemical studies were performed on the obtained HAp/S53P4 BG composite coatings and compared against the uncoated AZ31 alloy.The results showed a significant decrease in hydrogen evolution(at least 98%)when the bioactive coating was applied on the Mg alloy during evaluation in simulated body fluid(SBF).

Qualitative exploration of home life experiences and care needs among elderly patients with temporary intestinal stomas

BACKGROUND This study employed a phenomenological research approach within qualitative research to explore the challenges encountered by elderly individuals with temporary colostomies in managing their daily lives and care needs.Protecting the anus surgery combined with temporary colostomy has emerged as a prevalent treatment modality for low rectal cancer.However,the ileostomy is susceptible to peri-stoma skin complications,as well as fluid,electrolyte,and nutritional imbalances,posing challenges to effective management.The successful selfmanagement of patients is intricately linked to their adjustment to temporary colostomy;nonetheless,there remains a dearth of research examining the factors influencing self-care among temporary colostomy patients and the obstacles they confront.AIM To investigate the lived experiences,perceptions,and care requirements of temporary colostomy patients within their home environment,with the ultimate goal of formulating a standardized management protocol.METHODS Over the period of June to August 2023,a purposive sampling technique was utilized to select 12 patients with temporary intestinal stomas from a tertiary hospital in Shanghai,China.Employing a phenomenological research approach,a semi-structured interview guide was developed,and qualitative interviews were conducted using in-depth interview techniques.The acquired data underwent coding,analysis,organization,and summarization following Colaizzi’s seven-step method.RESULTS The findings of this study revealed that the experiences and needs of patients with temporary intestinal stomas can be delineated into four principal themes:Firstly,Temporary colostomy patients bear various burdens and concerns about the uncertainty of disease progression;secondly,patients exhibit limited self-care capabilities and face information deficits,resulting in heightened reliance on healthcare professionals;thirdly,patients demonstrate the potential for internal motivation through proactive self-adjustment;and finally,patients express a significant need for emotional and social support.CONCLUSION Home-living patients with temporary intestinal stomas confront multifaceted challenges encompassing burdens,inadequate self-care abilities,informational deficits,and emotional needs.Identifying factors influencing patients’self-care at home and proposing strategies to mitigate barriers can serve as a foundational framework for developing and implementing nursing interventions tailored to the needs of patients with temporary intestinal stomas.

Laser speckle contrast imaging to predict the effect of temporary spinal cord stimulation in postherpetic neuralgia patients: A prospective observational study

Temporary spinal cord stimulation(tSCS)can effectively reduce the pain and severity of postherpetic neuralgia(PHN).However,there are no effective and objective methods for predicting the effects of tSCS on PHN.Laser speckle contrast imaging(LSCI)is frequently used in neurology to evaluate the effectiveness of treatment.To assess the accuracy of LSCI in predicting the impact of tSCS on PHN,14 adult patients receiving tSCS treatments for spinal nerve-innervated(C6-T2)PHN participated in this observational study.Visual analog scale(VAS)assessments and LSCI bloodflow images of the-ngers were recorded after the tSCS procedure.The results showed that the VAS scores of all patients decreased signi-cantly.Moreover,the bloodflow index(BFI)values were signi-cantly higher than they were before the procedure.Increased bloodflow and pain alleviation were positively correlated.The-ndings indicated that spinal nerve PHN(C6-T2)was signi-cantly reduced by tSCS.Pain alleviation by tSCS was positively correlated with increased bloodflow in the hand.The effect of tSCS on PHN may thus be predicted using an independent and consistent indicator such as LSCI.

Clinical Efficacy of GBR Technique Combined with Temporary Bridgework-Guided Gingival Contouring in Treating Upper Anterior Tooth Loss with Labial Bone Defects

Objective:To investigate the clinical effect of the guided bone regeneration(GBR)technique combined with temporary bridgework-guided gingival contouring in treating upper anterior tooth loss with labial bone defects.Methods:From July 2023 to April 2024,80 patients with upper anterior tooth loss and labial bone defects were admitted to the hospital and selected as evaluation samples.They were divided into an observation group(n=40)and a control group(n=40)using a numerical table lottery scheme.The control group received treatment with the GBR technique,while the observation group received treatment with the GBR technique combined with temporary bridges to guide gingival contouring.The two groups were compared in terms of clinical red aesthetic scores(PES),labial alveolar bone density,labial bone wall thickness,gingival papillae,gingival margin levels,and patient satisfaction.Results:The PES scores of patients in the observation group were higher than those in the control group after surgery(P<0.05).The bone density of the labial alveolar bone and the thickness of the labial bone wall in the observation group were higher than those in the control group.The levels of gingival papillae and gingival margins were lower in the observation group after surgery(P<0.05).Additionally,patient satisfaction in the observation group was higher than in the control group(P<0.05).Conclusion:The GBR technique combined with temporary bridge-guided gingival contouring for treating upper anterior tooth loss with labial bone defects can improve the aesthetic effect of gingival soft tissue,increase alveolar bone density and the thickness of the labial bone wall,and enhance patient satisfaction.This approach is suitable for widespread application in healthcare institutions.

Plugging behaviors of temporary plugging particles in hydraulic fractures

Using the visualized experimental device of temporary plugging in hydraulic fractures, the plugging behaviors of temporary plugging particles with different sizes and concentrations in hydraulic fractures were experimentally analyzed under the conditions of different carrier fluid displacements and viscosities. The results show that the greater the carrier fluid viscosity and displacement, the more difficult it is to form a plugging layer, and that the larger the size and concentration of the temporary plugging particle, the less difficult it is to form a plugging layer. When the ratio of particle size to fracture width is 0.45, the formation of the plugging layer is mainly controlled by the mass concentration of the temporary plugging particle and the viscosity of the carrier fluid, and a stable plugging layer cannot form if the mass concentration of the temporary plugging particle is less than 20 kg/m^(3)or the viscosity of the carrier fluid is greater than 3 mPa·s. When the ratio of particle size to fracture width is 0.60, the formation of the plugging layer is mainly controlled by the mass concentration of the temporary plugging particle, and a stable plugging layer cannot form if the mass concentration of the temporary plugging particle is less than 10 kg/m^(3). When the ratio of particle size to fracture width is 0.75, the formation of the plugging layer is basically not affected by other parameters, and a stable plugging layer can form within the experimental conditions. The formation process of plugging layer includes two stages and four modes. The main controlling factors affecting the formation mode are the ratio of particle size to fracture width, carrier fluid displacement and carrier fluid viscosity.

Complex fracture propagation model and plugging timing optimization for temporary plugging fracturing in naturally fractured shale

In this paper,a viscoelasticity-plastic damage constitutive equation for naturally fractured shale is deduced,coupling nonlinear tensile-shear mixed fracture mode.Dynamic perforation-erosion on fluid re-distribution among multi-clusters are considered as well.DFN-FEM(discrete fracture network combined with finite element method)was developed to simulate the multi-cluster complex fractures propagation within temporary plugging fracturing(TPF).Numerical results are matched with field injection and micro-seismic monitoring data.Based on geomechanical characteristics of Weiyuan deep shale gas reservoir in Sichuan Basin,SW China,a multi-cluster complex fractures propagation model is built for TPF.To study complex fractures propagation and the permeability-enhanced region evolution,intersecting and competition mechanisms between the fractures before and after TPF treatment are revealed.Simulation results show that:fracture from middle cluster is restricted by the fractures from side-clusters,and side-clusters plugging is benefit for multi fractures propagation in uniformity;optimized TPF timing should be delayed within a higher density or strike of natural fractures;Within a reservoir-featured natural fractures distribution,optimized TPF timing for most clustered method is 2/3 of total fluid injection time as the optimal plugging time under different clustering modes.

Emergency internal iliac artery temporary occlusion after massive hemorrhage during surgery of cesarean scar pregnancy:A case report

BACKGROUND Cesarean scar pregnancy(CSP)is rare but may result in uterine rupture during pregnancy or massive hemorrhage during abortion procedures.Awareness of this condition is increasing,and most patients with CSP are now diagnosed early and can be managed safely.However,some atypical patients are misdiagnosed,and their surgical risks are underestimated,increasing the risk of fatal hemorrhage.CASE SUMMARY A 27-year-old Asian woman visited our institution because of abnormal pregnancy,and she was diagnosed with a hydatidiform mole through transvaginal ultrasound(TVS).Under hysteroscopy,a large amount of placental tissue was found in the scar of the lower uterine segment,and a sudden massive hemorrhage occurred during the removal process.The bilateral internal iliac arteries were temporarily blocked under laparoscopy,and scar resection and repair were rapidly performed.She was discharged in good condition 5 d after the operation.CONCLUSION Although TVS is widely used in the diagnosis of CSP,delays in the diagnosis of atypical CSP remain.Surgical treatment following internal iliac artery temporary occlusion may be an appropriate management method for unanticipated massive hemorrhage during CSP surgery.

Theoretical Study on the Temporary Cavity Caused by a High Speed Projectile When Wounding Living Organisms

Analyzes and calculates the process of development of a temporary cavity in the muscle directly after a projectile wounds organisms at a high speed. The muscle is taken as a non compressible Voigt Kelvin viscoelastic fluid model, on the assumption of moving in a radial direction and on spherical symmetry, a theoretical model proposed using the basic equations of the non Newtonian fluid mechanics. The model can well describe the pulsation process of the temporary cavity and changes of pressure in the cavity. The calculated results are in correspondence with the experimental results. The model can be applied in the quantitative analysis of a temporary cavity.

Open abdomen in gastrointestinal surgery:Which technique is the best for temporary closure during damage control?

AIM To compare the 3 main techniques of temporary closure of the abdominal cavity,vacuum assisted closure(vacuum-assisted closure therapy- VAC),Bogota bag and Barker technique,in damage control surgery.METHODS After systematic review of the literature,33 articles were selected to compare the efficiency of the three procedures.Criteria such as cost,infections,capacity of reconstruction of the abdominal wall,diseases associated with the technique,among others were analyzed.RESULTS The Bogota bag and Barker techniques present as advantage the availability of material and low cost,what is not observed in the VAC procedure.The VAC technique is the most efficient,not only because it reduces the tension on the boarders of the lesion,but also removes stagnant fluids and debris and acts at cellular level increasing cell proliferation and division.Bogota bag presents the higher rates of skin laceration and evisceration,greater need for a stent for draining fluids and wash-ups,higher rates of intestinal adhesion to the abdominal wall.The Barker technique presents lack of efficiency in closing the abdominal wall and difficulty on maintaining pressure on the dressing.The VAC dressing can generate irritation and dermatitis when the drape is applied,in addition to pain,infection and bleeding,as well as toxic shock syndrome,anaerobic sepsis and thrombosis.CONCLUSION The VAC technique,showed to be superior allowing a better control of liquid on the third space,avoiding complications such as fistula with small mortality,low infection rate,and easier capability on primary closure of the abdominal cavity.

A comprehensive review on biocompatible Mg-based alloys as temporary orthopaedic implants:Current status,challenges,and future prospects

Mg and its alloys are drawing huge attention since the last two decades as a viable option for temporary implants applications.A commendable progress has already been made in the development of these alloys.The biodegradable nature of Mg,appreciable biocompatibility of elemental Mg,and its close resemblance to natural bone in terms of density and elastic modulus make them highly preferable option amongst other available alternatives in this field.This review article presents an overview covering the recent advancements made in the field of Mg-based biodegradable implants for orthopaedic implant applications.The paper focuses on alloy development and fabrication techniques,the state of the art of important Mg-based alloy systems in terms of their mechanical properties,in-vitro and in-vivo degradation behaviour and cytotoxicity.Further,the paper reviews the current progress achieved in the clinical transition of Mg-based alloys for orthopaedic fixtures.The review also includes the degradation mechanisms of the alloys in physiological environment and highlights the mismatch existing between the rate of bone healing and alloy degradation due to rapid corrosion of the alloys in such environment,which has still restricted their widespread application.Finally,the surface coating techniques available for the alloys as an effective way to reduce the degradation rate are reviewed,followed by a discussion on the future research prospects.

Modified sewage sludge as temporary landfill cover material

In order to study the feasibility of modified sewage sludge as landfill cover material and its performance in a complex landfill environment, strength and hydraulic conductivity tests were conducted. The permeability requirements for daily and interim covers were analyzed first. Based on saturated-unsaturated seepage calculations, it is suggested that approximately 1.0×10^-4 cm/s and 1.0 × 10^-5 cm/s are the appropriate values for the hydraulic conductivities of daily and interim covers, respectively. The strength and permeability requirements of the mixtures, when used as an interim cover, can be met at a sludge：lime：cement：silt：tire-derived aggregate （TDA） weight ratio of 100：15：5：70：15. Results also demonstrate that the solid content ratio of modified sewage sludge, which should be greater than 60% when modified sewage sludge is used as a temporary cover material, is crucial to both strength and hydraulic performance. In addition, as the duration of soaking of modified sewage sludge in synthetic leachate increases, the unconfined compressive strength increases, and the hydraulic conductivity decreases slightly or fluctuates between 1.0×10^-5 cm/s and 1.0 × 10^-6 cm/s, still meeting the requirements for an interim cover. The reduction in hydraulic conductivity of modified sewage sludge under the effect of synthetic leachate, as well as the long-term and environmental performance of the modified sewage sludge, should be examined in future studies.

Development of degradable pre-formed particle gel(DPPG)as temporary plugging agent for petroleum drilling and production

Temporary plugging agent(TPA)is widely used in many fields of petroleum reservoir drilling and production,such as temporary plugging while drilling and petroleum well stimulation by diverting in acidizing or fracturing operations.The commonly used TPA mainly includes hard particles,fibers,gels,and composite systems.However,current particles have many limitations in applications,such as insufficient plugging strength and slow degradation rate.In this paper,a degradable pre-formed particle gel(DPPG)was developed.Experimental results show that the DPPG has an excellent static swelling effect and self-degradation performance.With a decrease in the concentration of total monomers or cross-linker,the swelling volume of the synthesized DPPG gradually increases.However,the entire self-degradation time gradually decreases.The increase in 2-acrylamide-2-methylpropanesulfonic acid(AMPS)in the DPPG composition can significantly increase its swelling ratio and shorten the self-degradation time.Moreover,DPPG has excellent high-temperature resistance(150°C)and high-salinity resistance(200,000 mg/L NaCl).Core displacement results show that the DPPG has a perfect plugging effect in the porous media(the plugging pressure gradient was as high as 21.12 MPa),and the damage to the formation after degradation is incredibly minor.Therefore,the DPPG can be used as an up-and-coming TPA in oil fields.

Urgent Tracheal Resection and Reconstruction Assisted by Temporary Cardiopulmonary Bypass:a Case Report

SEVERE tracheal stenosis can not only cause criti- cal medical problems such as severe shortness of breath, hypoxia, and even orthopnea, but also impose overwhelming challenges on thephysicians, particularly the anesthesiologist. Life-threa- tening airway obstruction can make the patient＇s gas ex- change extremely difficult. Though several options could be offered regarding the treatment of tracheal stenosis, normally, tracheal resection and following reconstruction is the first choice for severe airway stenosis.1 Successful surgical intervention relies on the close communication and cooperation between surgeons and anesthesiologists.

Impact of Intraoperative Blood Pressure Control and Temporary Parent Artery Blocking on Prognosis in Cerebral Aneurysms Surgery

Objective In cerebral aneurysm clipping and embolization, blood pressure control and temporaryparent artery blocking are common methods to prevent aneurysm rupture. Their influence on the prognosis isuncertain. In this study, we try to find out the association between methods above and prognostic indicators.

Following Control for a UUV using Temporary Path Generation Guidance

A path following control algorithm for an unmanned underwater vehicle（UUV） using temporary path generation guidance was proposed in this paper.Owing to different initial states of the vehicle,such as position and orientation,the path following control in the horizontal plane may yield a poor performance.To deal with the negative effect induced by initial states,a temporary path generation was presented based on the relationship between the original reference path and the vehicle’s initial states.With different relative positions between the vehicle and reference path,including out of straight lines,as well as inside and outside a circle,the related temporary paths guiding the vehicle to the reference path were able to be generated in real time.The vehicle was guided to steer along the temporary path until it reached the tangent point at the reference path,where the controller was designed using the input-output feedback linearization method.Simulation results demonstrated that the proposed algorithm is effective under the three different situations mentioned above.

Evaluation of Long-term Stability of Vertical Control in Hyperdivergent Patients Treated with Temporary Anchorage Devices

This study aims to evaluate,the long-term stability of vertical control in hyperdivergent patients treated with temporary anchorage devices.The sample included 20 hyperdivergent patients without anterior open bite.The temporary anchorage devices were used to intrude the upper incisor and molars for vertical control.Lateral cephalograms were established prior to treatment,immediately after treatment,and during retention. The upper molars and incisors were intruded by 1.33 mm and 1.41 mm after treatment (P<0.05).U6-PP increased by 0.11 mm and 0.23 mm during the first and second stages of retention (P>0.05).U1-PP was found to possess a significant extrusion of 1.2 mm during the first stage (P<0.05),which increased by 0.68 mm during the second stage (P>0.05). The mandibular plane angle (MP-SN)decreased by 2.58 degrees following treatment, and underwent a relapse of 0.51 degree and 0.42 degree during the first and second stages of retention respectively (P>0.05).No significant soft tissue changes occurred,with the exception of increased upper lip length during the second stage (P<0.05).Maxillary anterior and posterior intrusions,counter clockwise rotation,of the mandibular plane,and improved profiles can be successfully achieved following treatment with vertical control. During the first stage of retention (less than three years),intruded molars and incisors both exhibited some extrusion,and molars had better long-term stability than incisors. During the second stage of retention (three to six years),the therapeutic effects appeared stable,with the exception of some increase in upper lip length.Rotated mandibular plane remained stable during the entire retention period.

Minimally Invasive Percutaneous Catheter Drainage versus Open Laparotomy with Temporary Closure for Treatment of Abdominal Compartment Syndrome in Patients with Early-stage Severe Acute Pancreatitis

This study aimed to examine the clinical efficacy of minimally invasive percutaneous catheter drainage（PCD） versus open laparotomy with temporary closure in the treatment of abdominal compartment syndrome（ACS） in patients with early-stage severe acute pancreatitis（SAP）. Clinical data of 212 patients who underwent PCD and 61 patients who were given open laparotomy with temporary closure in our hospital over the last 10-year period were retrospectively analyzed, and outcomes were compared, including total and post-decompression intensive care unit（ICU） and hospital stays, physiological data, organ dysfunction, complications, and mortality. The results showed that the organ dysfunction scores were similar between the PCD and open laparotomy groups 72 h after decompression. In the PCD group, 134 of 212（63.2%） patients required postoperative ICU support versus 60 of 61（98.4%） in the open laparotomy group（P〈0.001）. Additionally, 87（41.0%） PCD patients experienced complications as compared to 49 of 61（80.3%） in the open laparotomy group（P〈0.001）. There were 40（18.9%） and 32（52.5%） deaths, respectively, in the PCD and open laparotomy groups（P〈0.001）. In conclusion, minimally invasive PCD is superior to open laparotomy with temporary closure, with fewer complications and deaths occurring in PCD group.

A bull-heading water control technique of thermo-sensitive temporary plugging agent

Aimed at the disadvantages of secondary damage to oil layers caused by the conventional bull-heading water control technique, a thermo-sensitive temporary plugging agent for water control was synthesized by water solution polymerization and applied in the field with a new secondary temporary plugging technique. The optimization and performance evaluation of thermo-sensitive temporary plugging agent were carried out through laboratory experiments. The optimized formula is as follows:(6%-8%) acrylamide +(0.08%-0.12%) ammonium persulfate +(1.5%-2.0%) sepiolite +(0.5%-0.8%) polyethylene glycol diacrylate. The thermo-sensitive temporary plugging agent is suitable for formation temperatures of 70-90 ?C, it has high temporary plugging strength(5-40 k Pa), controllable degradation time(1-15 d), the apparent viscosity after degradation of less than 100 m Pa?S and the permeability recovery value of simulated cores of more than 95%. Based on the research results, secondary temporary plugging technique was used in a horizontal well in the Jidong Oilfield. After treatment, the well saw a drop of water cut to 27%, and now it has a water cut of 67%, its daily increased oil production was 4.8 t, and the cumulative oil increment was 750 t, demonstrating that the technique worked well in controlling water production and increasing oil production.