Experimental Investigation on the Factors Affecting Proppant Flowback Performance

Abstract Proppant flowback is a significant issue in the field of fractured well production. In order to investigate the influencing relationships among the parameters affecting proppant flowback, the weight of proppant flowback within different conditions was tested by applying a fracture simulation experiment device. During the experiments, the flowback velocity of the fracturing fluid, the viscosity of the fracturing fluid, the proppant particle size, and the effective closure pressure were studied. The experimental results indicated that the flowback velocity of the fracturing fluid is critical for proppant flowback. The weight of the flowback proppant increases as the fracturing fluid flowback velocity increases. Proppant flowback mainly occurs in the early stage of fracturing fluid flowback; more than 75% of the flowback volume of the proppant was carried by 33.33% of the fracturing fluid flowback volume. The weight of the flowback proppant decreases as the flowback fracturing fluid viscosity decreases. Using a larger particle size proppant or upon increasing effective closure pressure also can decrease the weight of the flowback proppant.

Download Full-text

From Exploratory Tunnel to Base Tunnel: Hard Rock TBM Performance Prediction by Means of a Stochastic Approach

Rock Mechanics and Rock Engineering ◽

10.1007/s00603-020-02226-9 ◽

2020 ◽

Vol 53 (12) ◽

pp. 5473-5487 ◽

Cited By ~ 1

Author(s):

Andrea Rispoli ◽

Anna Maria Ferrero ◽

Marilena Cardu

Keyword(s):

Performance Prediction ◽

Early Stage ◽

Tunnel Boring Machine ◽

Stochastic Approach ◽

Critical Issue ◽

Utilization Factor ◽

Tbm Performance ◽

Factors Affecting ◽

Tunnel Section ◽

Input Variables

AbstractTunnel boring machine (TBM) performance prediction is often a critical issue in the early stage of a tunnelling project, mainly due to the unpredictable nature of some important factors affecting the machine performance. In this regard, deterministic approaches are normally employed, providing results in terms of average values expected for the TBM performance. Stochastic approaches would offer improvement over deterministic methods, taking into account the parameter variability; however, their use is limited, since the level of information required is often not available. In this study, the data provided by the excavation of the Maddalena exploratory tunnel were used to predict the net and overall TBM performance for a 2.96 km section of the Mont Cenis base tunnel by using a stochastic approach. The preliminary design of the TBM cutterhead was carried out. A prediction model based on field penetration index, machine operating level and utilization factor was adopted. The variability of the parameters involved was analysed. A procedure to take into account the correlation between the input variables was described. The probability of occurrence of the outcomes was evaluated, and the total excavation time expected for the tunnel section analysed was calculated.

Download Full-text

A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

Advances in Mechanical Engineering ◽

10.1177/16878140211017812 ◽

2021 ◽

Vol 13 (5) ◽

pp. 168781402110178

Author(s):

Zhengang Liu ◽

Weinan Diao ◽

Zhenxia Liu ◽

Fei Zhang

Keyword(s):

Particle Size ◽

Particle Deposition ◽

Numerical Study ◽

Stokes Number ◽

Capture Efficiency ◽

Particle Capture ◽

Factors Affecting ◽

Pressure Surface ◽

Deposition Area ◽

Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

Download Full-text

Interactive effects between travel behaviour and COVID-19: a questionnaire study

Transportation Safety and Environment ◽

10.1093/tse/tdab003 ◽

2021 ◽

Author(s):

Jinbao Zhang ◽

Jaeyoung Lee

Keyword(s):

Early Stage ◽

Travel Behaviour ◽

Interactive Effects ◽

Factors Affecting ◽

Individual Level ◽

Passenger Volume ◽

Spatial Autoregressive ◽

Railway Passenger ◽

The Individual ◽

And Control

Abstract This study has two main objectives: (i) to analyse the effect of travel characteristics on the spreading of disease, and (ii) to determine the effect of COVID-19 on travel behaviour at the individual level. First, the study analyses the effect of passenger volume and the proportions of different modes of travel on the spread of COVID-19 in the early stage. The developed spatial autoregressive model shows that total passenger volume and proportions of air and railway passenger volumes are positively associated with the cumulative confirmed cases. Second, a questionnaire is analysed to determine changes in travel behaviour after COVID-19. The results indicate that the number of total trips considerably decreased. Public transport usage decreased by 20.5%, while private car usage increased by 6.4%. Then the factors affecting the changes in travel behaviour are analysed by logit models. The findings reveal significant factors, including gender, occupation and travel restriction. It is expected that the findings from this study would be helpful for management and control of traffic during a pandemic.

Download Full-text

Pots as alternative and sustainable fishing gears in the Mediterranean Sea: an overview

Reviews in Fish Biology and Fisheries ◽

10.1007/s11160-021-09676-6 ◽

2021 ◽

Author(s):

Andrea Petetta ◽

Massimo Virgili ◽

Stefano Guicciardi ◽

Alessandro Lucchetti

Keyword(s):

Mediterranean Sea ◽

Early Stage ◽

Spiny Lobster ◽

Mesh Size ◽

Octopus Vulgaris ◽

Target Species ◽

Factors Affecting ◽

Fishing Gears ◽

Pros And Cons ◽

The Mediterranean

AbstractStock overexploitation, bycatch, discards and gear impacts on the environment are outstanding issues for Mediterranean fisheries. The adoption of alternative fishing gears is an appealing solution to ensure a more sustainable exploitation of resources. We discuss the pros and cons of pots as alternative gears by reviewing their main designs, spatial distribution and target species in the Mediterranean basin. We assessed the technical factors affecting the catch efficiency of the different pot designs for four target species: spiny lobster, Palinurus elephas; Norway lobster, Nephrops norvegicus; common octopus, Octopus vulgaris and pandalid shrimps, Plesionika spp. We found that pot volume is important to catch Octopus; mesh size to catch Nephrops and Plesionika; entrance surface to catch Octopus, Nephrops and Plesionika; pot shape/colour and entrance shape/position to catch Octopus and Plesionika; and bait type to catch Octopus and Nephrops. The literature review shows that pot fisheries have several considerable advantages over conventional gears, especially in terms of discards, bycatch, seabed impacts (particularly compared with bottom trawls and passive set nets), size and species selectivity, gear depredation, catch quality and gear cost, besides saving time and labour. Disadvantages hampering their wider diffusion include ghost fishing, a low catch of finfish species, the narrow range of species targeted by each pot design and the current early stage of research. These data make a clear case for using pots as alternative gears to traditional ones in the Mediterranean Sea in some areas and seasons to catch certain target species.

Download Full-text

Physicochemical factors affecting the wettability of copper mine blasting dust

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00411-x ◽

2021 ◽

Author(s):

Longzhe Jin ◽

Jianguo Liu ◽

Jingzhong Guo ◽

Jiaying Wang ◽

Tianyang Wang

Keyword(s):

Particle Size ◽

Physicochemical Properties ◽

Pore Structure ◽

Total Pore Volume ◽

Open Pit ◽

X Rays ◽

Factors Affecting ◽

Copper Mine ◽

Mineral Components ◽

Hydrophobic Component

AbstractTo investigate the factors affecting the wettability of copper mine blasting dust, the primary blasting dust was collected from an open-pit copper mine and separated into hydrophilic blasting dust (HLBD) and hydrophobic blasting dust (HBBD) using water flotation method. The physicochemical properties of HLBD and HBBD were measured and compared with each other. The properties included particle size distributions (PSDs), micromorphologies, pore structures, mineral components and surface organic carbon functional groups. The results show that particle size and pore structure of the blasting dust are the main factors affecting its wettability. Specifically, particle size of HBBD is smaller than that of HLBD, and their respiratory dust (less than 10 µm) accounts for 61.74 vol% and 53.00 vol%, respectively. The pore structure of HBBD is more developed, and the total pore volume of HBBD is 1.66 times larger than that of HLBD. The identical mineral compositions were detected in HLBD and HBBD by X-rays diffraction (XRD); however, the surface organic hydrophobic component of HBBD is slightly larger than that of HLBD, this may be the reason for the poor wettability of HBBD. This study is significant to understand the effects of physicochemical properties of copper mine blasting dust on its wettability.

Download Full-text

Quality of life in breast cancer sufferers

International Journal of Health Care Quality Assurance ◽

10.1108/ijhcqa-05-2015-0057 ◽

2016 ◽

Vol 29 (7) ◽

pp. 721-732 ◽

Cited By ~ 1

Author(s):

Ahmed Essmat Shouman ◽

Nahla Fawzy Abou El Ezz ◽

Nivine Gado ◽

Amal Mahmoud Ibrahim Goda

Keyword(s):

Breast Cancer ◽

Quality Of Life ◽

Family Income ◽

Early Stage ◽

Functional Domain ◽

Related Factors ◽

Specific Patient ◽

Content Type ◽

Factors Affecting

Purpose – The purpose of this paper is to measure health-related quality of life (QOL) among patients with early stage cancer breast under curative treatment at department of oncology and nuclear medicine at Ain Shams University Hospitals. Identify factors affecting QOL among these patients. Design/methodology/approach – A cross-sectional study measured QOL among early stage female breast cancer (BC) patients and determined the main factors affecting their QOL. Three interviewer administered questionnaires were used. Findings – The physical domain mostly affected in BC patients and the functional domain least. Socio-demographic factors that significantly affected BC patients QOL scores were patient age, education, having children and family income. Specific patient characteristics include caregiver presence – a factor that affected different QOL scores. Age at diagnosis, affection in the side of the predominant hand, post-operative chemotherapy and difficulty in obtaining the medication were the disease-related factors that affected QOL scores. Originality/value – The final model predicting QOL for early stage female BC patients included age, education and difficulty in obtaining the medication as determinants for total QOL score. Carer presence was the specific patient characteristic that affected different QOL scores.

Download Full-text

Factors affecting the hydrogen cyanide potential of forage sorghum.

Australian Journal of Agricultural Research ◽

10.1071/ar9901093 ◽

1990 ◽

Vol 41 (6) ◽

pp. 1093 ◽

Cited By ~ 26

Author(s):

JL Wheeler ◽

C Mulcahy ◽

JJ Walcott ◽

GG Rapp

Keyword(s):

Water Stress ◽

Light Intensity ◽

Hydrogen Cyanide ◽

Dry Matter ◽

Early Stage ◽

Phosphorus Fertilizer ◽

Factors Affecting ◽

Forage Sorghum ◽

Plant Maturity ◽

Selection For

The effect of seven factors, namely genotype, plant maturity, nitrogen fertilizer, phosphorus fertilizer, water stress, light intensity and temperature, on the hydrogen cyanide potential (HCNp) of forage sorghum was studied in three pot experiments. Fivefold differences occurred between genotypes in HCNp, with a breeder's line, X45106, selected for low HCNp having a maximum of 520 mg HCN kg-1 DM (dry matter) compared with 2300 and 2450 mg kg-1 DM for cvs Zulu and Silk respectively. In X45 106, HCNp (mg HCN kg-1 DM) declined curvilinearly with age d (days from sowing) (HCNp=8460- 320d+ 3.1d2) and linearly in Silk (HCNp = 9020 - 110d), but the decline in Zulu was not statistically significant. Nitrogen (equivalent to 200 kg ha-1 of N) increased HCN, (P< 0.001), but more so in full light (100 mg kg-1 compared with 1430 mg kg-1) than in 50% shade (190 mg kg-1 compared with 690 mg kg-1). In one experiment, acute water stress appeared to reduce HCNp, but this was confounded with the strong decline due to aging. In another study, acute water stress had no effect on HCNp. Neither the application of superphosphate nor change in light intensity, nor change in temperature had a direct significant effect on HCNp in these studies. Breeding and selection for low HCNp appears a promising approach to ensuring that sorghum plants will provide non-toxic forage from an early stage of growth.

Download Full-text