Urban underutilized spaces,often the secondary by-products of large infrastructure projects,are often overlooked,despite their potential to enhance city life.With meaningful design interventions,these neglected areas ...Urban underutilized spaces,often the secondary by-products of large infrastructure projects,are often overlooked,despite their potential to enhance city life.With meaningful design interventions,these neglected areas can be transformed into inclusive public environments that offer social,environmental,and cultural value.This research investigates how modular,temporary installations beneath Toronto’s Gardiner Expressway,in Canada,can enhance thermal comfort and foster community engagement during the shoulder seasons.Using a multi-step methodology,including literature review,thermal comfort guidelines,site-specific climate analysis,and precedent studies,the research identifies key design strategies tailored to the unique microclimatic and social conditions of under-bridge spaces.The study culminates in the proposal of a flexible system of movable panels that provide wind protection,solar control,and opportunities for gathering,interaction,and rest.By reimagining these unnoticed infrastructure zones as adaptable,climate-responsive public spaces,this research contributes to sustainable urban design and highlights the importance of design strategies that address the challenges of a warming and increasingly variable climate.展开更多
BACKGROUND Intramural pregnancy is rare,with an unclear etiology and pathophysiology.Surgical,medical,and expectant management options are available for this condition.However,most reported cases are managed surgicall...BACKGROUND Intramural pregnancy is rare,with an unclear etiology and pathophysiology.Surgical,medical,and expectant management options are available for this condition.However,most reported cases are managed surgically.Despite the risks of massive intraoperative bleeding and acute and long-term complications,uterine artery embolization is often selected.Temporary occlusion of the bilateral uterine arteries during surgery is associated with fewer complications.CASE SUMMARY We reported the case of a patient who was diagnosed with intramural pregnancy approximately one month after medical abortion.We performed laparoscopic resection with hysteroscopy.Since the lesion had abundant blood flow,we temporarily blocked the bilateral uterine arteries to prevent massive intraop-erative bleeding.The surgical process went smoothly.The postoperative course was uneventful.CONCLUSION Temporary occlusion of the bilateral uterine arteries in the treatment of intramural pregnancy may prevent excessive uterine bleeding during surgery.展开更多
Objective: This study assessed the effects of consuming acetic acid bacteria (Gluconacetobacter hansenii GK-1) for 12 weeks on fatigue induced by temporary mental stress. Methods: This randomized, double-blind, placeb...Objective: This study assessed the effects of consuming acetic acid bacteria (Gluconacetobacter hansenii GK-1) for 12 weeks on fatigue induced by temporary mental stress. Methods: This randomized, double-blind, placebo-controlled, parallel-group study included 100 healthy male and female adults aged 20 - 64 years. Participants consumed either the G. hansenii GK-1 supplement (9 × 10⁹ cells/day) or a placebo daily for 12 weeks. The impact of temporary mental stress on fatigue in G. hansenii GK-1 was assessed using a Visual Analog Scale (VAS) before the study began and after 12 weeks of supplementation. Results: Subjective fatigue measured by Visual Analog Scale (VAS) showed a significant decrease in fatigue induced by temporary mental stress after 12 weeks of consumption in the G. hansenii GK-1 group compared with the placebo group. No adverse events were attributed to G. hansenii GK-1. These findings confirm that continuous oral ingestion of G. hansenii GK-1 by healthy Japanese adults reduces feelings of fatigue caused by temporary mental stress.展开更多
This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion w...This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion with multi-cluster sand jetting perforation.The effects of temporary plugging agent(TPA)particle size,TPA concentration,single-cluster perforation number and cluster number on plugging pressure,multi-fracture diversion pattern and distribution of TPAs were investigated.A combination of TPAs with small particle sizes within the fracture and large particle sizes within the segment is conducive to increasing the plugging pressure and promoting the diversion of multi-fractures.The addition of fibers can quickly achieve ultra-high pressure,but it may lead to longitudinal fractures extending along the wellbore.The temporary plugging peak pressure increases with an increase in the concentration of the TPA,reaching a peak at a certain concentration,and further increases do not significantly improve the temporary plugging peak pressure.The breaking pressure and temporary plugging peak pressure show a decreasing trend with an increase in single-cluster perforation number.A lower number of single-cluster perforations is beneficial for increasing the breaking pressure and temporary plugging peak pressure,and it has a more significant control on the propagation of multi-cluster fractures.A lower number of clusters is not conducive to increasing the total number and complexity of artificial fractures,while a higher number of clusters makes it difficult to achieve effective plugging.The TPAs within the fracture is mainly concentrated in the complex fracture areas,especially at the intersections of fractures.Meanwhile,the TPAs within the segment are primarily distributed near the perforation cluster apertures which initiated complex fractures.展开更多
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...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.展开更多
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...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.展开更多
Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing alo...Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing along horizontal wells and plays an important role in increasing oil and gas production. However,the transportation and sealing law of temporary plugging balls(TPBs) in the perforation section of horizontal wells is still unclear. Using COMSOL computational fluid dynamics and a particle tracking module, we simulate the transportation process of TPBs in a horizontal wellbore and analyse the effects of the ball density, ball diameter, ball number, fracturing fluid injection rate, and viscosity on the plugging efficiency of TPB transportation. This study reveals that when the density of TPBs is close to that of the fracturing fluid and a moderate diameter of the TPB is used, the plugging efficiency can be substantially enhanced. The plugging efficiency is greater when the TPB number is close to twice the number of perforations and is lower when the number of TPBs is three times the number of perforations.Adjusting the fracturing fluid injection rate from low to high can control the position of the TPBs,improving plugging efficiency. As the viscosity of the fracturing fluid increases, the plugging efficiency of the perforations decreases near the borehole heel and increases near the borehole toe. In contrast, the plugging efficiency of the central perforation is almost unaffected by the fracturing fluid viscosity. This study can serve as a valuable reference for establishing the parameters for temporary plugging and fracturing.展开更多
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 HA...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).展开更多
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 s...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.展开更多
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.M...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.展开更多
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 experim...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.展开更多
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 viscoel...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.展开更多
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 biodeg...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.展开更多
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 s...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.展开更多
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 fracturin...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.展开更多
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 ...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.展开更多
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 thi...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.展开更多
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 anest...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.展开更多
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 a...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.展开更多
The development of unconventional petroleum resources has gradually become an important succession for increasing oil production.However,the related engineers and researchers are paying more and more attention to the ...The development of unconventional petroleum resources has gradually become an important succession for increasing oil production.However,the related engineers and researchers are paying more and more attention to the application of temporary plugging agents(TPAs)for their efficient development.TPAs can expand the stimulated reservoir volume(SRV)and facilitate the flow of oil and gas to the bottom of the well.Particle-gels used as temporary plugging agents have the characteristics of the simple injection process,good deformation,high plugging strength,and complete self-degradation performance,which have been widely applied in recent years.In this paper,five samples of DPPG polymerized by different molecular weights of cross-linking agents were prepared.In addition,infrared spectroscopy analysis,differential calorimetry scanning(DSC)analysis,static particle gel swelling and degradation performance evaluation experiments,and dynamic temporary plugging performance experiments in cores were conducted at 34°C.Results show that as the molecular weight of the cross-linking agent(at 0.01 g)in the DPPG molecule decreased from 1,000 to 200 Da,the fewer cross-linking sites of DPPG,the looser the microscopic three-dimensional mesh structure formed.The swelling ratio increased from 7 to 33 times.However,the complete degradation time increased from 40 to 210 min.Moreover,the DSC results confirmed that the higher the molecular weight of the cross-linking agent,the worse is chemical stability and the more prone it to self-degradation.DPPG samples had good temporary plugging performance in reservoir cores.DPPGs prepared by the cross-linking agent with smaller molecular weight has a stronger swelling ratio,higher gel strength,and greater plugging strength in the core permeabilities.Moreover,the degraded DPPG is less damaging to the cores.However,their slower degradation rates take a slightly longer times to reach complete degradation.The results of this paper can provide new ideas and a theoretical basis for the development of particle gel-type temporary plugging agents(TPA)with controllable degradation time in low-temperature reservoirs.It can help to expand the application range of existing DPPG reservoir conditions.展开更多
文摘Urban underutilized spaces,often the secondary by-products of large infrastructure projects,are often overlooked,despite their potential to enhance city life.With meaningful design interventions,these neglected areas can be transformed into inclusive public environments that offer social,environmental,and cultural value.This research investigates how modular,temporary installations beneath Toronto’s Gardiner Expressway,in Canada,can enhance thermal comfort and foster community engagement during the shoulder seasons.Using a multi-step methodology,including literature review,thermal comfort guidelines,site-specific climate analysis,and precedent studies,the research identifies key design strategies tailored to the unique microclimatic and social conditions of under-bridge spaces.The study culminates in the proposal of a flexible system of movable panels that provide wind protection,solar control,and opportunities for gathering,interaction,and rest.By reimagining these unnoticed infrastructure zones as adaptable,climate-responsive public spaces,this research contributes to sustainable urban design and highlights the importance of design strategies that address the challenges of a warming and increasingly variable climate.
文摘BACKGROUND Intramural pregnancy is rare,with an unclear etiology and pathophysiology.Surgical,medical,and expectant management options are available for this condition.However,most reported cases are managed surgically.Despite the risks of massive intraoperative bleeding and acute and long-term complications,uterine artery embolization is often selected.Temporary occlusion of the bilateral uterine arteries during surgery is associated with fewer complications.CASE SUMMARY We reported the case of a patient who was diagnosed with intramural pregnancy approximately one month after medical abortion.We performed laparoscopic resection with hysteroscopy.Since the lesion had abundant blood flow,we temporarily blocked the bilateral uterine arteries to prevent massive intraop-erative bleeding.The surgical process went smoothly.The postoperative course was uneventful.CONCLUSION Temporary occlusion of the bilateral uterine arteries in the treatment of intramural pregnancy may prevent excessive uterine bleeding during surgery.
文摘Objective: This study assessed the effects of consuming acetic acid bacteria (Gluconacetobacter hansenii GK-1) for 12 weeks on fatigue induced by temporary mental stress. Methods: This randomized, double-blind, placebo-controlled, parallel-group study included 100 healthy male and female adults aged 20 - 64 years. Participants consumed either the G. hansenii GK-1 supplement (9 × 10⁹ cells/day) or a placebo daily for 12 weeks. The impact of temporary mental stress on fatigue in G. hansenii GK-1 was assessed using a Visual Analog Scale (VAS) before the study began and after 12 weeks of supplementation. Results: Subjective fatigue measured by Visual Analog Scale (VAS) showed a significant decrease in fatigue induced by temporary mental stress after 12 weeks of consumption in the G. hansenii GK-1 group compared with the placebo group. No adverse events were attributed to G. hansenii GK-1. These findings confirm that continuous oral ingestion of G. hansenii GK-1 by healthy Japanese adults reduces feelings of fatigue caused by temporary mental stress.
基金Supported by the National Natural Science Foundation of China(51974332).
文摘This study conducted temporary plugging and diversion fracturing(TPDF)experiments using a true triaxial fracturing simulation system within a laboratory setting that replicated a lab-based horizontal well completion with multi-cluster sand jetting perforation.The effects of temporary plugging agent(TPA)particle size,TPA concentration,single-cluster perforation number and cluster number on plugging pressure,multi-fracture diversion pattern and distribution of TPAs were investigated.A combination of TPAs with small particle sizes within the fracture and large particle sizes within the segment is conducive to increasing the plugging pressure and promoting the diversion of multi-fractures.The addition of fibers can quickly achieve ultra-high pressure,but it may lead to longitudinal fractures extending along the wellbore.The temporary plugging peak pressure increases with an increase in the concentration of the TPA,reaching a peak at a certain concentration,and further increases do not significantly improve the temporary plugging peak pressure.The breaking pressure and temporary plugging peak pressure show a decreasing trend with an increase in single-cluster perforation number.A lower number of single-cluster perforations is beneficial for increasing the breaking pressure and temporary plugging peak pressure,and it has a more significant control on the propagation of multi-cluster fractures.A lower number of clusters is not conducive to increasing the total number and complexity of artificial fractures,while a higher number of clusters makes it difficult to achieve effective plugging.The TPAs within the fracture is mainly concentrated in the complex fracture areas,especially at the intersections of fractures.Meanwhile,the TPAs within the segment are primarily distributed near the perforation cluster apertures which initiated complex fractures.
基金supported by the National Natural Science Foundation of China(Nos.31972929 and 62231025)the Research Program of Shanghai Science and Technology Committee(Nos.21140901300 and 20DZ2220400)+3 种基金the Natural Science Foundation of Chongqing,China(No.CSTB2022NSCQ-MSX0767)the Interdisciplinary Program of Shanghai Jiao Tong University(Nos.YG2021ZD22 and YG2023LC04)the Foundation of National Center for Translational Medicine(Shanghai)SHU Branch(No.SUITM-2023008)the Cross-disciplinary Research Fund of Shanghai Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine(No.JYJC202108).
文摘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.
基金The study was reviewed and approved by the Science and Research Office of Tong Ren Hospital(Shanghai), No. AF/SC-08/04.0.
文摘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.
基金supported by the National Natural Science Foundation of China (No. 52074250)。
文摘Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing along horizontal wells and plays an important role in increasing oil and gas production. However,the transportation and sealing law of temporary plugging balls(TPBs) in the perforation section of horizontal wells is still unclear. Using COMSOL computational fluid dynamics and a particle tracking module, we simulate the transportation process of TPBs in a horizontal wellbore and analyse the effects of the ball density, ball diameter, ball number, fracturing fluid injection rate, and viscosity on the plugging efficiency of TPB transportation. This study reveals that when the density of TPBs is close to that of the fracturing fluid and a moderate diameter of the TPB is used, the plugging efficiency can be substantially enhanced. The plugging efficiency is greater when the TPB number is close to twice the number of perforations and is lower when the number of TPBs is three times the number of perforations.Adjusting the fracturing fluid injection rate from low to high can control the position of the TPBs,improving plugging efficiency. As the viscosity of the fracturing fluid increases, the plugging efficiency of the perforations decreases near the borehole heel and increases near the borehole toe. In contrast, the plugging efficiency of the central perforation is almost unaffected by the fracturing fluid viscosity. This study can serve as a valuable reference for establishing the parameters for temporary plugging and fracturing.
基金the National Council of Humanities,Science,and Technology(CONAHCYT)through the"Investigadores por Mexico"program,projects 848 and 881。
文摘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).
基金supported by the Clinical Frontier Technology Program of the First A±liated Hospital of Jinan University,China(No.JNU1AFCFTP-2022-a01212)the Clinical Research Funds for the First Clinical Medicine College of Jinan University(Grant No.2018006).
文摘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.
文摘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.
基金Supported by National Natural Science Foundation of China (U21A20105)Science and Technology Innovation Fund of PetroChina (2020D-5007-0208)。
文摘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.
文摘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.
文摘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.
文摘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.
基金This work was supported by the Research Foundation of China University of Petroleum-Beijing at Karamay(No.XQZX20200010)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2019D01B57)+3 种基金the University Scientific Research Project of Xinjiang Uygur Autonomous Region(No.XJEDU2019Y067)the Xinjiang Uygur Autonomous Region Innovation Environment Construction Project(No.2019Q025)the Sichuan Province Regional Innovation Cooperation Project(No.2020YFQ0036)the CNPC Strategic Cooperation Science and Technology Project(ZLZX2020-01-04-04)。
文摘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.
基金supported by the National Natural Science Foundation of China(Grant No.51008120)the Youth Science and Technology Morning Program of Wuhan(Grant No.201271031418)the Natural Science Foundation of Hubei Province(Grant No.2014CFB606)
文摘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.
文摘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.
文摘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.
基金Supported by the National Natural Science Foundation of China(52192622,52204005,U20A20265)Sichuan Outstanding Young Scientific and Technological Talents Project(2022JDJQ0007).
文摘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.
基金supported by the Research Foundation of China University of Petroleum-Beijing at Karamay (No. YJ2018B02002 and XQZX20200010)the Natural Science Foundation of Xinjiang Uygur Autonomous Region (No. 2021D01E23 and 2019D01B57)+3 种基金the University Scientific Research Project of Xinjiang Uygur Autonomous Region (No. XJEDU2019Y067)the Xinjiang Uygur Autonomous Region Innovation Environment Construction Project (No. 2019Q025)the Sichuan Province Regional Innovation Cooperation Project (No. 2020YFQ0036)the CNPC Strategic Cooperation Science and Technology Project (ZLZX2020-01-04-04)
文摘The development of unconventional petroleum resources has gradually become an important succession for increasing oil production.However,the related engineers and researchers are paying more and more attention to the application of temporary plugging agents(TPAs)for their efficient development.TPAs can expand the stimulated reservoir volume(SRV)and facilitate the flow of oil and gas to the bottom of the well.Particle-gels used as temporary plugging agents have the characteristics of the simple injection process,good deformation,high plugging strength,and complete self-degradation performance,which have been widely applied in recent years.In this paper,five samples of DPPG polymerized by different molecular weights of cross-linking agents were prepared.In addition,infrared spectroscopy analysis,differential calorimetry scanning(DSC)analysis,static particle gel swelling and degradation performance evaluation experiments,and dynamic temporary plugging performance experiments in cores were conducted at 34°C.Results show that as the molecular weight of the cross-linking agent(at 0.01 g)in the DPPG molecule decreased from 1,000 to 200 Da,the fewer cross-linking sites of DPPG,the looser the microscopic three-dimensional mesh structure formed.The swelling ratio increased from 7 to 33 times.However,the complete degradation time increased from 40 to 210 min.Moreover,the DSC results confirmed that the higher the molecular weight of the cross-linking agent,the worse is chemical stability and the more prone it to self-degradation.DPPG samples had good temporary plugging performance in reservoir cores.DPPGs prepared by the cross-linking agent with smaller molecular weight has a stronger swelling ratio,higher gel strength,and greater plugging strength in the core permeabilities.Moreover,the degraded DPPG is less damaging to the cores.However,their slower degradation rates take a slightly longer times to reach complete degradation.The results of this paper can provide new ideas and a theoretical basis for the development of particle gel-type temporary plugging agents(TPA)with controllable degradation time in low-temperature reservoirs.It can help to expand the application range of existing DPPG reservoir conditions.
