scholarly journals Formation of Oil-Particle-Aggregates: Numerical Model Formulation and Calibration

2021 ◽  
Vol 8 ◽  
Author(s):  
Linlin Cui ◽  
Courtney K. Harris ◽  
Danielle R. N. Tarpley
Keyword(s):  
Fractal Dimension ◽  
Size Distribution ◽  
Sediment Concentration ◽  
River Plume ◽  
Model Parameters ◽  
Dimensional Model ◽  
Outer Continental Shelf ◽  
Collision Efficiency ◽  
Particle Aggregates ◽  
High Sediment

When oil spills occur in turbid waters, the oil droplets and mineral grains can combine to form oil-particle aggregates (OPAs). The formation of OPAs impacts the vertical transport of both the oil and the mineral grains; especially increasing deposition of oil to the seabed. Though the coastal oceans can be very turbid, to date, few numerical ocean models have accounted for aggregation processes that form OPAs. However, interactions between oil and mineral aggregates may be represented using techniques developed to account for sediment aggregation. As part of Consortium for Simulation of Oil Microbial Interactions in the Ocean (CSOMIO), we modified an existing, population dynamics-based sediment flocculation model to develop OPAMOD, a module that accounts for the formation of OPAs. A zero-dimensional model using OPAMOD is shown to be capable of reproducing the size distribution of aggregates from existing laboratory experimental results. Also using the zero-dimensional model, sensitivity tests were performed on two model parameters, the fractal dimension and collision efficiency. Results showed that fractal dimension played a role in the OPA size distribution by influencing the effective particle density, which modified the number concentration of flocs for a given mass concentration. However, the modeled particle characteristics and oil sequestration were relatively insensitive to collision efficiency. To explore OPA formation for an outer continental shelf site, two simulations were conducted using a one-dimensional (vertical) implementation of the model. One scenario had high sediment concentration near the seabed to mimic storm-induced resuspension. The other scenario represented river plume sediment delivery by having high sediment concentration in surface waters. Results showed that OPA formation was sensitive to the vertical distribution of suspended sediment, with the river plume scenario creating more OPA, and sequestering more oil within OPA than the storm resuspension scenario. OPAMOD was developed within the Coupled Ocean-Atmosphere-Wave-and-Sediment Transport (COAWST) modeling system, therefore the methods and parameterizations from this study are transferrable to a three-dimensional coupled oil-sediment-microbial model developed by CSOMIO within the COAWST framework.

NANOSCALE PORE SIZE DISTRIBUTION EFFECTS ON GAS PRODUCTION FROM FRACTAL SHALE ROCKS

Fractals ◽  
2019 ◽  
Vol 27 (08) ◽  
pp. 1950142
Author(s):  
JINZE XU ◽  
KELIU WU ◽  
RAN LI ◽  
ZANDONG LI ◽  
JING LI ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Gas Transport ◽  
Gas Production ◽  
Lower Sensitivity ◽  
Apparent Permeability ◽  
Transport Efficiency ◽  
Nanoscale Pore

Effect of nanoscale pore size distribution (PSD) on shale gas production is one of the challenges to be addressed by the industry. An improved approach to study multi-scale real gas transport in fractal shale rocks is proposed to bridge nanoscale PSD and gas filed production. This approach is well validated with field tests. Results indicate the gas production is underestimated without considering a nanoscale PSD. A PSD with a larger fractal dimension in pore size and variance yields a higher fraction of large pores; this leads to a better gas transport capacity; this is owing to a higher free gas transport ratio. A PSD with a smaller fractal dimension yields a lower cumulative gas production; this is because a smaller fractal dimension results in the reduction of gas transport efficiency. With an increase in the fractal dimension in pore size and variance, an apparent permeability-shifting effect is less obvious, and the sensitivity of this effect to a nanoscale PSD is also impaired. Higher fractal dimensions and variances result in higher cumulative gas production and a lower sensitivity of gas production to a nanoscale PSD, which is due to a better gas transport efficiency. The shale apparent permeability-shifting effect to nanoscale is more sensitive to a nanoscale PSD under a higher initial reservoir pressure, which makes gas production more sensitive to a nanoscale PSD. The findings of this study can help to better understand the influence of a nanoscale PSD on gas flow capacity and gas production.

Fractal Characteristics of Sandstone Cutting Fracture under Mechanical Shock Loading Conditions

2012 ◽  
Vol 226-228 ◽  
pp. 1789-1794 ◽  
Author(s):  
Shu Ren Wang ◽  
Paul Hagan ◽  
Yan Cheng
Keyword(s):  
Fractal Dimension ◽  
Size Distribution ◽  
Structural Integrity ◽  
Theoretical Calculations ◽  
Mesh Size ◽  
Rock Cutting ◽  
Weight Percent ◽  
Rock Breaking ◽  
Engineering Practice ◽  
Mechanical Shock

It is the key to guide rock-breaking design and engineering practice for how to obtain a reasonable test indicator to assess the cuttability of the rock. Some sandstone samples were tested by using the linear rock cutting machine in the school of mining engineering, University of New South Wales (UNSW), Australia. The curves characteristics for the weight percent of the broken debris with the mesh size distribution were obtained through the screening statistics. Furthermore, the fractal dimension of the specimen broken debris was derived through theoretical calculations and statistical analysis. The results showed that the rock cutting fragmentation is of significant fractal features under the mechanical shock loads. The broken debris fractal dimension of the structural integrity specimens is bigger, the range of the fractal dimension is smaller and the broken debris size distribution is more even than that of the poor structural integrity specimens. The fractal dimension is the ideal test indicator to assess and analysis the rock-breaking degree.

scholarly journals Green Preparation, Spheroidal, and Superior Property of Nano-1,3,5,7-Tetranittro-1,3,5,7-Tetrazocane

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xinlei Jia ◽  
Jingyu Wang ◽  
Conghua Hou ◽  
Yingxin Tan
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fractal Theory ◽  
Crystal Form ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
The Impact

Herein, a green process for preparing nano-HMX, mechanical demulsification shearing (MDS) technology, was developed. Nano-HMX was successfully fabricated via MDS technology without using any chemical reagents, and the fabrication mechanism was proposed. Based on the “fractal theory,” the optimal shearing time for mechanical emulsification was deduced by calculating the fractal dimension of the particle size distribution. The as-prepared nano-HMX was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). And the impact sensitivities of HMX particles were contrastively investigated. The raw HMX had a lower fractal dimension of 1.9273. The ideal shearing time was 7 h. The resultant nano-HMX possessed a particle size distribution ranging from 203.3 nm to 509.1 nm as compared to raw HMX. Nano-HMX particles were dense spherical, maintaining β-HMX crystal form. In addition, they had much lower impact sensitivity. However, the apparent activation energy as well as thermal decomposition temperature of nano-HMX particles was decreased, attributing to the reduced probability for hotspot generation. Especially when the shearing time was 7 h, the activation energy was markedly decreased.

Fractal Dimension of Particle Aggregates in Magnetic Fields

2004 ◽  
Vol 39 (12) ◽  
pp. 2839-2862 ◽  
Author(s):  
Ching-Ju Chin ◽  
Shih-Chien Lu ◽  
Sotira Yiacoumi ◽  
Costas Tsouris
Keyword(s):  
Fractal Dimension ◽  
Magnetic Fields ◽  
Particle Aggregates

scholarly journals NUMERICAL MODEL OF 3D MORPHODYNAMIC AFTER OFFSHORE NOURISHMENT

2011 ◽  
Vol 1 (32) ◽  
pp. 55 ◽  
Author(s):  
Masamitsu Kuroiwa ◽  
Yoko Shibutani ◽  
Yuhei Matsubara ◽  
Takayuki Kuchiishi ◽  
Mazen Abualtyef
Keyword(s):  
Numerical Model ◽  
Diffusion Equation ◽  
Suspended Sediment Concentration ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Sand Material

A three-dimensional model of morphodynamics after offshore nourishment was developed. In the presented model, the 3D beach evolution model that is not only after nourishment but also taking into account the nourishment process of injected sand material. In order to consider the injected process of sand, the computation using the advection-diffusion equation for suspended sediment concentration was adapted in the model. The presented model was applied to an idealized beach with two groins in order to investigate the performance of the model, and then, the model was applied to a field observation result for shoreface nourishment carried out at the Egmond aan Zee in the Netherlands. Finally, the applicability of the presented model was discussed from the computed results.

scholarly journals CALCULATION OF THE RATE OF NET ON-OFFSHORE SEDIMENT TRANSPORT ON THE BASIS OF FLUX CONCEPT

1984 ◽  
Vol 1 (19) ◽  
pp. 91 ◽  
Author(s):  
Ichiro Deguchi ◽  
Toru Sawaragi
Keyword(s):  
Sediment Transport ◽  
Water Depth ◽  
Sediment Concentration ◽  
Suspended Load ◽  
Spatial Variations ◽  
Sediment Flux ◽  
Bed Load ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Two Dimensional Model

Time and spatial variations of sediment concentration of both bed load and suspended load in the process of two-dimensional beach deformation were investigated experimentally. At the same time, the relation between the velocities of water-particle and sediment migration was analyzed theoretically. By using those results,a net rate of on-offshore sediment_ transport in the process of two-dimensional model beach deformation qf was calculated on the basis of sediment flux. It is found that Qf coincides fairly well with .the net rate of on-offshore sediment transport calculated from the change of water depth.

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