Numerical Simulation of Asphaltene Precipitation and Deposition during Natural Gas and CO_(2) Injection

Asphaltene deposition is a significant problem during gas injection processes,as it can block the porous medium,the wellbore,and the involved facilities,significantly impacting reservoir productivity and ultimate oil recovery.Only a few studies have investigated the numerical modeling of this potential effect in porous media.This study focuses on asphaltene deposition due to natural gas and CO_(2) injection.Predictions of the effect of gas injection on asphaltene deposition behavior have been made using a 3D numerical simulation model.The results indicate that the injection of natural gas exacerbates asphaltene deposition,leading to a significant reduction in permeability near the injection well and throughout the reservoir.This reduction in permeability strongly affects the ability of gas toflow through the reservoir,resulting in an improvement of the displacement front.The displacement effi-ciency of the injection gas process increases by up to 1.40%when gas is injected at 5500 psi,compared to the scenario where the asphaltene model is not considered.CO_(2) injection leads to a miscible process with crude oil,extracting light and intermediate components,which intensifies asphaltene precipitation and increases the viscosity of the remaining crude oil,ultimately reducing the recovery rate.

Cross-upgrading of biomass hydrothermal carbonization and pyrolysis for high quality blast furnace injection fuel production:Physicochemical characteristics and gasification kinetics analysis

The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel.The results showed that after upgrading,the volatile content of biochar ranged from 16.19%to 45.35%,and the alkali metal content,ash content,and specific surface area were significantly reduced.The optimal route for biochar pro-duction is hydrothermal carbonization-pyrolysis(P-HC),resulting in biochar with a higher calorific value,C=C structure,and increased graphitization degree.The apparent activation energy(E)of the sample ranges from 199.1 to 324.8 kJ/mol,with P-HC having an E of 277.8 kJ/mol,lower than that of raw biomass,primary biochar,and anthracite.This makes P-HC more suitable for blast furnace injection fuel.Additionally,the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits.P-HC of-fers the highest potential for carbon emission reduction,capable of reducing emissions by 96.04 kg/t when replacing 40wt%coal injec-tion.

Shenqi Fuzheng injection alleviates chemotherapy-induced cachexia by restoring glucocorticoid signaling in hypothalamus

Chemotherapy-induced cachexia(CIC)is a debilitating condition characterized by weight loss,muscle atrophy,and anorexia[1].While peripheral mechanisms of cachexia have been extensively studied,the involvement of the central nervous system(CNS)in CIC is often overlooked.Chemotherapeutic drugs cause stress responses and inflammation,which may impact the hypothalamus and disrupt systemic energy and neuroendocrine functions.Understanding hypothalamic roles in regulating these processes can provide insights into CIC's mechanisms and aid in developing novel therapies.

Experimental study of the influencing factors and mechanisms of the pressure-reduction and augmented injection effect by nanoparticles in ultra-low permeability reservoirs

Nanoparticles(NPs)have gained significant attention as a functional material due to their ability to effectively enhance pressure reduction in injection processes in ultra-low permeability reservoirs.NPs are typically studied in controlled laboratory conditions,and their behavior in real-world,complex environments such as ultra-low permeability reservoirs,is not well understood due to the limited scope of their applications.This study investigates the efficacy and underlying mechanisms of NPs in decreasing injection pressure under various injection conditions(25—85℃,10—25 MPa).The results reveal that under optimal injection conditions,NPs effectively reduce injection pressure by a maximum of 22.77%in core experiment.The pressure reduction rate is found to be positively correlated with oil saturation and permeability,and negatively correlated with temperature and salinity.Furthermore,particle image velocimetry(PIV)experiments(25℃,atmospheric pressure)indicate that the pressure reduction is achieved by NPs through the reduction of wall shear resistance and wettability change.This work has important implications for the design of water injection strategies in ultra-low permeability reservoirs.

Numerical analysis of hydraulic fracture propagation in deep shale reservoir with different injection strategies

Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow reservoirs.Therefore,it is urgent to investigate particular injection strategies that can optimize breakdown pressure and fracturing efficiency to address the increasing demands for deep shale reservoir stimulation.In this study,the efficiency of various stimulation strategies,including multi-cluster simultaneous fracturing,modified alternating fracturing,alternating shut-in fracturing,and cyclic alternating fracturing,was evaluated.Subsequently,the sensitivity of factors such as the cycle index,shut-in time,cluster spacing,and horizontal permeability was investigated.Additionally,the flow distribution effect within the wellbore was discussed.The results indicate that relative to multi-cluster simultaneous fracturing,modified alternating fracturing exhibits reduced susceptibility to the stress shadow effect,which results in earlier breakdown,extended hydraulic fracture lengths,and more consistent propagation despite an increase in breakdown pressure.The alternating shut-in fracturing benefits the increase of fracture length,which is closely related to the shut-in time.Furthermore,cyclic alternating fracturing markedly lowers breakdown pressure and contributes to uniform fracture propagation,in which the cycle count plays an important role.Modified alternating fracturing demonstrates insensitivity to variations in cluster spacing,whereas horizontal permeability is a critical factor affecting fracture length.The wellbore effect restrains the accumulation of pressure and flow near the perforation,delaying the initiation of hydraulic fractures.The simulation results can provide valuable numerical insights for optimizing injection strategies for deep shale hydraulic fracturing.

A Probabilistic Trust Model and Control Algorithm to Protect 6G Networks against Malicious Data Injection Attacks in Edge Computing Environments

Future 6G communications are envisioned to enable a large catalogue of pioneering applications.These will range from networked Cyber-Physical Systems to edge computing devices,establishing real-time feedback control loops critical for managing Industry 5.0 deployments,digital agriculture systems,and essential infrastructures.The provision of extensive machine-type communications through 6G will render many of these innovative systems autonomous and unsupervised.While full automation will enhance industrial efficiency significantly,it concurrently introduces new cyber risks and vulnerabilities.In particular,unattended systems are highly susceptible to trust issues:malicious nodes and false information can be easily introduced into control loops.Additionally,Denialof-Service attacks can be executed by inundating the network with valueless noise.Current anomaly detection schemes require the entire transformation of the control software to integrate new steps and can only mitigate anomalies that conform to predefined mathematical models.Solutions based on an exhaustive data collection to detect anomalies are precise but extremely slow.Standard models,with their limited understanding of mobile networks,can achieve precision rates no higher than 75%.Therefore,more general and transversal protection mechanisms are needed to detect malicious behaviors transparently.This paper introduces a probabilistic trust model and control algorithm designed to address this gap.The model determines the probability of any node to be trustworthy.Communication channels are pruned for those nodes whose probability is below a given threshold.The trust control algorithmcomprises three primary phases,which feed themodel with three different probabilities,which are weighted and combined.Initially,anomalous nodes are identified using Gaussian mixture models and clustering technologies.Next,traffic patterns are studied using digital Bessel functions and the functional scalar product.Finally,the information coherence and content are analyzed.The noise content and abnormal information sequences are detected using a Volterra filter and a bank of Finite Impulse Response filters.An experimental validation based on simulation tools and environments was carried out.Results show the proposed solution can successfully detect up to 92%of malicious data injection attacks.

Wetting front migration model of ion-adsorption rare earth during the multi-hole unsaturated liquid injection

In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still unclear.Besides,wetting front migration distance and leaching time are usually required to optimize the leaching process.In this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head height.At the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were identical.At the postintersection stage,the intersection accelerated the wetting front migration.By using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the intersection.Finally,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was established.Error analysis results showed that the proposed model can accurately simulate the infiltration process under experimental conditions.The research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.

Tofacitinib combined with local low-dose ixekizumab injection benefits those with peripheral psoriatic arthritis

Dear Editor,Treating psoriatic arthritis(PsA)is always difficult.Systemic treatments can be administered either orally or through intramuscular and intra-articular injection,including conventional synthetics,biologics and targeted synthetic disease-modifying antirheumatic drugs[1].The alternatives,topical external therapies,are not effective on joint lesions due to drug permeability issues.Drugs injected into the articular cavity are also unsuitable for small peripheral joint lesions,the most common manifestations of PsA.The limited treatment options for PsA present a challenge.

Does HSP27 injection induce glaucoma damage in mice?

In a further aging society,excellent eyesight is an integral part of overall well-being and quality of life.Preserving good vision is crucial to maintaining mobility,independence,and mental health.There can be several reasons for visual impairment in elderly people,these include age-related macular degeneration,the leading cause of vision loss among older adults,cataract,glaucoma,diabetic retinopathy,retinal detachment,and others.

Large-scale physical simulation of injection and production of hot dry rock in Gonghe Basin,Qinghai Province,China

Based on the independently developed true triaxial multi-physical field large-scale physical simulation system of in-situ injection and production,we conducted physical simulation of long-term multi-well injection and production in the hot dry rocks of the Gonghe Basin,Qinghai Province,NW China.Through multi-well connectivity experiments,the spatial distribution characteristics of the natural fracture system in the rock samples and the connectivity between fracture and wellbore were clarified.The injection and production wells were selected to conduct the experiments,namely one injection well and two production wells,one injection well and one production well.The variation of several physical parameters in the production well was analyzed,such as flow rate,temperature,heat recovery rate and fluid recovery.The results show that under the combination of thermal shock and injection pressure,the fracture conductivity was enhanced,and the production temperature showed a downward trend.The larger the flow rate,the faster the decrease.When the local closed area of the fracture was gradually activated,new heat transfer areas were generated,resulting in a lower rate of increase or decrease in the mining temperature.The heat recovery rate was mainly controlled by the extraction flow rate and the temperature difference between injection and production fluid.As the conductivity of the leak-off channel increased,the fluid recovery of the production well rapidly decreased.The influence mechanisms of dominant channels and fluid leak-off on thermal recovery performance are different.The former limits the heat exchange area,while the latter affects the flow rate of the produced fluid.Both of them are important factors affecting the long-term and efficient development of hot dry rock.

Background diseases and the number of previous intravitreal aflibercept injections on immediate intraocular pressure increase and vitreous reflux rate in phakic eyes

●AIM:To evaluate the effect of background diseases and number of previous intravitreal aflibercept injections(IVAIs)on immediate intraocular pressure(IOP)increase and vitreous reflux(VR)rate and to evaluate the correlation of both age and axial length with immediate IOP increase and VR rate.●METHODS:This study included 105 patients with cystoid macular edema secondary to retinal vein occlusion,35 patients with diabetic macular edema,69 patients with neovascular age-related macular degeneration(nAMD),and 12 patients with myopic choroidal neovascularization,which underwent first-time IVAI.The correlation of immediate IOP increase and VR rates with the four background diseases was investigated.Moreover,the correlation of age with immediate IOP increase and VR rate as well as correlation of axial length with immediate IOP increase and VR rate were evaluated.Further,54 patients with nAMD were treated with IVAI>10 times(multiple IVAIs).Moreover,the correlation of immediate IOP increase and VR rates with first-time and multiple IVAIs in nAMD was determined.●RESULTS:The immediate IOP increase(P=0.16)and VR rates(P=0.50)were almost similar among the four background diseases.The immediate postinjection IOP and age,VR rate and age,immediate postinjection IOP and axial length,or VR rate and axial length were not correlated in the four background diseases.The immediate IOP increase(P=0.66)and VR rates(P=0.28)did not significantly differ between first-time and multiple IVAIs in nAMD.●CONCLUSION:Background diseases and number of previous IVAIs have no effect on immediate IOP increase and VR rate.Further,age and axial length have no correlation on immediate IOP increase and VR rate.

A New Heat Transfer Model for Multi-Gradient Drilling with Hollow Sphere Injection

Multi-gradient drilling is a new offshore drilling method.The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise control of the wellbore pressure.In this study,a new heat transfer model is proposed by which the variable mass flow is properly taken into account.Using this model,the effects of the main factors influencing the wellbore temperature are analyzed.The results indicate that at the position where the separation injection device is installed,the temperature increase of the fluid in the drill pipe is mitigated due to the inflow/outflow of hollow spheres,and the temperature drop of the fluid in the annulus also decreases.In addition,a lower separation efficiency of the device,a shallower installation depth and a smaller circulating displacement tend to increase the temperature near the bottom of the annulus,thereby helping to reduce the hydrate generation area and playing a positive role in the prevention and control of hydrates in deepwater drilling.

Endoscopic band ligation or endoscopic tissue adhesive injection in the treatment of gastric varices:Which is better?

The combination of endoscopic ultrasound with endoscopic treatment of type 1 gastric variceal hemorrhage may improve the robustness and generalizability of the findings in future studies.Moreover,the esophageal varices should also be included in the evaluation of treatment efficacy in subsequent studies to reach a more convincing conclusion.

Horizontal well spacing optimization and gas injection simulation for the ultra-low-permeability Yongjin reservoir

Optimal spacing for vertical wells can be effectively predicted with several published methods,but methods suitable for assessing the proper horizontal well spacing are rare.This work proposes a method for calculating the optimal horizontal well spacing for an ultra-low permeability reservoir e the Yongjin reservoir in the Juggar Basin,northwestern China.The result shows that a spacing of 640m is the most economical for the development of the reservoir.To better develop the reservoir,simulation approaches are used and a new model is built based on the calculated well spacing.Since the reservoir has an ultralow permeability,gas injection is regarded as the preferred enhanced oil recovery(EOR)method.Injection of different gases including carbon dioxide,methane,nitrogen and mixed gas are modelled.The results show that carbon dioxide injection is the most efficient and economical for the development of the reservoir.However,if the reservoir produces enough methane,reinjecting methane is even better than injecting carbon dioxide.

Effect of high-multiple water injection on rock pore structure and oil displacement efficiency

Experimental methods,including mercury pressure,nuclear magnetic resonance(NMR)and core(wateroil)displacement,are used to examine the effects of high-multiple water injection(i.e.water injection with high injected pore volume)on rock properties,pore structure and oil displacement efficiency of an oilfield in the western South China Sea.The results show an increase in the permeability of rocks along with particle migration,an increase in the pore volume and the average pore throat radius,and enhanced heterogeneity after high-multiple water injection.Compared with normal water injection methods,a high-multiple water injection is more effective in improving the oil displacement efficiency.The degree of recovery increases faster in the early stage due to the expansion of the swept area,and the transition from oil-wet to water-wet.The degree of recovery increases less in the late stage due to various factors,including the enhancement of heterogeneity in the rocks.Considering both the economic aspect and the production limit of water flooding,it is recommended to adopt other technologies to further enhance oil recovery after 300 PV water injection.

Characteristics of water alternating CO_(2)injection in low-permeability beach-bar sand reservoirs

Water flooding can be ineffective in highly heterogeneous low-permeability beach-bar sand reservoirs.The introduction of CO_(2)flooding helps boost the oil production of the reservoirs but only in an early stage.During the late stage of flooding,gas channeling would occur.Water alternating gas(CO_(2))(WAG)process can be used to delay gas channeling and improve the effect of CO_(2)injection,though its adaptability to beach-bar sand reservoirs remains unclear.In order to clarify CO_(2)injection characteristics in these reservoirs,experiments were carried out in high-temperature high-pressure NMR on-line displacement experiment apparatus to simulate different flooding modes on synthetic cores that can reflect the vertical heterogeneity of beach-bar reservoirs.Different CO_(2)injection modes were implemented on these cores and the displacement characteristics and residual oil distribution features during both WAG injection and continuous CO_(2)injection were analyzed quantitatively and qualitatively.The results show that the scheme of WAG injection after continuous CO_(2)injection can obtain better oil displacement efficiency than that of the scheme of continuous CO_(2)injection after WAG injection,but there is no significant difference in respect of oil displacement efficiency of WAG flooding between the mode of bar-injection e beach-production(injection into bar sand e production from beach sand)and the mode of beach-injection e beach-production(injection into and production from beach sand),with the former mode having a higher oil recovery rate.The wider pore-size distribution range of microscopic residual oil after WAG injection shows great potential of enhancing oil recovery from subsequent continuous gas injection.When WAG injection is implemented prior to continuous CO_(2)injection,the displacement effect of the latter is more significant.This research may provide a theoretical basis for CO_(2)EOR in this type of reservoirs.

Permanent Magnet Temperature Estimation for PMSMs Using Virtual Position-offset Injection

This paper proposes a virtual position-offset injection based permanent magnet temperature estimation approach for permanent magnet synchronous machines(PMSMs). The concept of virtual position-offset injection is mathematically transforming the machine model to a virtual frame with a position-offset. The virtual frame temperature estimation model is derived to calculate the permanent magnet temperature(PMT) directly from the measurements with computation efficiency. The estimation model involves a combined inductance term, which can simplify the establishment of saturation compensation model with less measurements. Moreover, resistance and inverter distorted terms are cancelled in the estimation model, which can improve the robustness to the winding temperature rise and inverter distortion. The proposed approach can achieve simplified computation in temperature estimation and reduced memory usage in saturation compensation. While existing model-based approaches could be affected by either the need of resistance and inverter information or complex saturation compensation. Experiments are conducted on the test machine to verify the proposed approach under various operating conditions.

Self-expanding metal stent for relieving the stricture after endoscopic injection for esophageal varices

BACKGROUND Esophageal stricture is one of the complications after esophageal varices sclero-therapy injection(ESI),and the incidence rate is between 2%-10%.AIM To explore the efficacy of self-expanding metal stent(SEMS)for the stricture after endoscopic injection with cyanoacrylate(CYA)and sclerotherapy for esophageal varices.METHODS We retrospectively analyzed the efficacy of SEMS to improve the stricture after endoscopic injection with CYA and sclerotherapy for esophageal varices in 4 patients from February 2023 to June 2023.RESULTS The strictures were improved in four patients after stenting.The stent was removed after two weeks because of chest pain with embedding into esophageal mucosa in one patient.The stent was removed after one month,however,the stent was reinserted because of the strictures happening again in two patients.The stent was removed after three months,however,the stent was reinserted because of the strictures happening again in one patient.The stent embedded into esophageal mucosa in three patients.There were 3 patients suffered reflux esophagitis,and the acid reflux was relieved by taking hydrotalcite.There was no other complication of esophageal perforation,bleeding from varices or infection.CONCLUSION SEMS may relieve the stricture which happened after endoscopic injection with CYA and sclerotherapy for esophageal varices.However,when we should remove the stent still needs to be explored.

Transparent cap adjusted the stent placed for stenosis after endoscopic injection of esophageal varices:A case report

BACKGROUND The stent embedded in the esophageal mucosa is one of the complications after stenting for esophageal stricture.We present a case of stent adjustment with the aid of a transparent cap after endoscopic injection of an esophageal varices stent.CASE SUMMARY A 61-year-old male patient came to the hospital with discomfort of the chest after the stent implanted for the stenosis because of endoscopic injection of esophageal varices.The gastroscopy was performed,and the stent embedded into the esophageal mucosa.At first,we pulled the recycling line for shrinking the stent,however,the mucosa could not be removed from the stent.Then a forceps was performed to remove the mucosa in the stent,nevertheless,the bleeding form the mucosa was obvious.And then,we used a transparent cap to scrape the mucosa along the stent,and the mucosa were removed successfully without bleeding.CONCLUSION A transparent cap helps gastroscopy to remove the mucosa embedded in the stent after endoscopic injection of the esophageal varices stent.

Intravitreal injection practice patterns among Chinese ophthalmologists

AIM:To describe the practice patterns of intravitreal injections(IVIs)among ophthalmologists in China.METHODS:This was a cross-sectional online survey.Ophthalmologists who had performed accumulated more than 100 injections were contacted by the Brightness Center,a hospital-based national network,to complete an anonymous,24-question,internet-based survey.They were surveyed on practices in injection techniques,pre-,and post-injections procedures.RESULTS:A total of 333 ophthalmologists from 28 provinces/municipalities/autonomous regions responded to the survey(50.68%response rate).The 91.29%of the respondents evaluated systemic risk factors by medical history,electrocardiogram(ECG)and blood test.All the respondents used pre-injection prophylactic antibiotics.Most checked intraocular pressure(IOP,99.1%)and blood pressure(96.1%)before injections.A majority of the respondents performed injections in the operating room(98.8%),wore masks(99.7%),gloves(99.4%)and sterile surgical clothing(96.1%),performed topical anesthetics(97.9%),and applied povidone-iodine(95.8%)pre-injection.The 61.26%of the respondents dilated pupil.About half of the respondents(51.05%)performed bilateral injections in the same setting.Superior temporal quadrant(40.54%)was the most frequent site of injection.Around three quarters used 30-gauge needles.Most respondents(97.9%)measured the site of injection from limbus.More than half(53.45%)performed conjunctiva displacement prior to injection.The 32.43%of the respondents checked IOP post-injection and 87.99%physicians checked hand motion(HM)or counting fingers(CF)after injection,while 36.94%observed optic nerve perfusion.All participants used topical antibiotics post-injections.Most physicians(91.89%)reviewed patients on the following day.CONCLUSION:This study provides a description of the real-world practice patterns in IVIs in China and offers critical information regarding education and training of ophthalmologists and amendment of local society guidelines.