Fourier Dzar Eljabbar Latief

TORTUOSITY–POROSITY RELATIONSHIP IN TWO-DIMENSIONAL FRACTAL MODEL OF POROUS MEDIA

Tortuosity (τ) of two-dimensional fractal model of porous media is investigated to study their relationship with porosity. Square full-walk technique is applied to obtain τ in a two-dimensional fractal model of porous substance constructed by Randomized Sierspinski Carpets. The numerical result is in good agreement with previous results and empirical relation between tortuosity and porosity given by τ ~ p(1 - ϕ) + 1 that was found by other using Lattice Gas Automata method for solving flow equation on two-dimensional porous substance constructed by randomly placed rectangles of equal size and with unrestricted overlap. Average tortuosity of the flow path decreases linearly as fractal dimension of pore increases at each fractal iteration. Both fractal dimension and iteration give almost the same linearly tortuosity–porosity relation. The type of random algorithm for constructing Randomized Sierspinski Carpets has no significant influence on the tortuosity–porosity relation.

Single energy micro CT SkyScan 1173 for the characterization of urinary stone

Knowledge of the composition of urinary stones is an essential part to determine suitable treatments for patients. The aim of this research is to characterize the urinary stones by using dual energy micro CT SkyScan 11173. This technique combines high-energy and low- energy scanning during a single acquisition. Six human urinary stones were scanned in vitro using 80 kV and 120 kV micro CT SkyScan 1173. Projected images were produced by micro CT SkyScan 1173 and then reconstructed using NRecon (in-house software from SkyScan) to obtain a complete 3D image. The urinary stone images were analysed using CT analyser to obtain information of internal structure and Hounsfield Unit (HU) values to determine the information regarding the composition of the urinary stones, respectively. HU values obtained from some regions of interest in the same slice are compared to a reference HU. The analysis shows information of the composition of the six scanned stones obtained. The six stones consist of stone number 1 (calcium+cystine), number 2 (calcium+struvite), number 3 (calcium+cystine+struvite), number 4 (calcium), number 5 (calcium+cystine+struvite), and number 6 (calcium+uric acid). This shows that dual energy micro CT SkyScan 1173 was able to characterize the composition of the urinary stone.

The effect of X-ray micro computed tomography image resolution on flow properties of porous rocks: MICRO COMPUTED TOMOGRAPHY IMAGE RESOLUTION

The study of digital rock physics has seen significant advances due to the development of X‐ray micro computed tomography scanning devices. One of the advantages of using such a device is that the pore structure of rock can be mapped down to the micrometre level in three dimensions. However, in providing such high‐resolution images (low voxel size), the resulting file sizes are necessarily large (of the order of gigabytes). Lower image resolution (high voxel size) produces smaller file sizes (of the order of hundreds of megabytes), but risks losing significant details. This study describes the effect of the image resolution obtained by means of hardware‐based and software‐based approach. Four samples of porous rock were scanned using a SkyScan 1173 High Energy Micro‐CT. We found that acquisition using increased pixel binning of the camera (hardware‐based resizing) significantly affects the calculated physical properties of the samples. By contrast, voxel resizing by means of a software‐based approach during the reconstruction process yielded less effect on the porosity and specific surface area of the samples. However, the decreasing resolution of the image obtained by both the hardware‐based and the software‐based approaches affects the permeability significantly. We conclude that simulating fluid flow through the pore space using the Lattice Boltzmann method to calculate the permeability has a significant dependency on the image resolution.

Three-dimensional visualization and characterization of cracks in geothermal reservoir rock using image analysis of reconstructed μCT images: A preliminary study

In most geothermal reservoirs, cracks are considered very important because of the ability to transport water vapor. In most cases, characterizations of cracks are often difficult to be performed. However, through the vast development of imaging technique, many researches have been conducted in order to obtain better understanding regarding the nature of cracks. Using micro-CT (μCT) scanning devices, i.e., the Skyscan 1173, we were able to obtain 3D images of geothermal reservoir rock from West Java. The rock sample was scanned using X-ray voltage of 130 kV and current of 61 μA. The reconstructed images have spatial resolution of 59.85 μm/pixel. Using CTVox and ImageViewer, we were able to visualize the cracks both in 2D and 3D perspective. We further performed image processing and analysis, i.e.: simple segmentation of pore-solid by thresholding the gray values and binarizing the images, de-noising (despeckling), and 3D structure analysis. From these analyses, we obtain the value of porosity of 6.27%, an...

Development of single fluid volume element method for simulation of transient fluid flow in self-siphons

A simple model for transient flow in a narrow pipe is presented in this work. The model is simply derived from Newtons second law of motion. As an example it is used to predict flow occurrence in two forms of self-siphon, which are inverted-U and M-like forms. Simulation for system consists only a vertical pipe is also presented since it is actually part of the both siphon systems. For the simple systems the model can have good predictions but for the complex system it can only have 89.6 % good prediction. Its simplicity can be used to illustrate how the interface between fluid and air, single fluid volume element (SFVE) moves along the siphon. The method itself is named as SFVE method.

Beam hardening and smoothing correction effects on performance of micro-ct SkyScan 1173 for imaging low contrast density materials

We have designed and fabricated phantom mimicking breast cancer composition known as a region that has low contrast density. The used compositions are a microcalcifications, fatty tissues and tumor mass by using Al2O3, C27H46O, and hard nylon materials. Besides, phantom also has a part to calculate low cost criteria /CNR (Contrast to Noise Ratio). Uniformity will be measured at water distillation medium located in a part of phantom scale contrast. Phantom will be imaged by using micro ct-sky scan 1173 high energy type, and then also can be quantified CT number to examine SkyScan 1173 performance in imaging low contrast density materials. Evaluation of CT number is done at technique configuration parameter using voltage of 30 kV, exposure 0.160 mAs, and camera resolution 560x560 pixel, the effect of image quality to reconstruction process is evaluated by varying image processing parameters in the form of beam hardening corrections with amount of 25%, 66% and100% with each smoothing level S10,S2 and S7. To ...

The experiment of magnesium ECAP miniplate as alternative biodegradable material (on male white New Zealand rabbits)

Study of biodegradations of Magnesium ECAP (Equal Channel Angular Pressing) miniplate in the osteosynthesis system has been used as a new material for plate and screw in oral and maxillofacial surgery. This miniplate and screw that were made of Magnesium ECAP were implanted in the femurs of New Zealand rabbits. The degradation process was detected through pocket gas that appeared in hard and soft tissues surrounding in the implanted miniplates and screws. From the changes on the tissues, we can assess the biodegradation process by measuring the gas pocket through micro-CT Scan. Upon the first month of study we euthanized the rabbits and made a micro-CT Scan to see how far the effect of the gas pocket was. Histological analyses were performed to investigate the local tissue response adjacent to the Magnesium ECAP miniplates. We analyzed the femur of a rabbit a month, three months, and five months after implantation. The result showed a degradation rate in the implanted Magnesium ECAP miniplate of 0.61±0.39 mm/year. Unlike the screws, miniplates have higher water content and blood flow than bone, therefore they degrade faster. This study shows promising results for further development of Magnesium ECAP and in the production of osteosynthesis material for rigid fixation in Oral and Maxillofacial skeleton.Study of biodegradations of Magnesium ECAP (Equal Channel Angular Pressing) miniplate in the osteosynthesis system has been used as a new material for plate and screw in oral and maxillofacial surgery. This miniplate and screw that were made of Magnesium ECAP were implanted in the femurs of New Zealand rabbits. The degradation process was detected through pocket gas that appeared in hard and soft tissues surrounding in the implanted miniplates and screws. From the changes on the tissues, we can assess the biodegradation process by measuring the gas pocket through micro-CT Scan. Upon the first month of study we euthanized the rabbits and made a micro-CT Scan to see how far the effect of the gas pocket was. Histological analyses were performed to investigate the local tissue response adjacent to the Magnesium ECAP miniplates. We analyzed the femur of a rabbit a month, three months, and five months after implantation. The result showed a degradation rate in the implanted Magnesium ECAP miniplate of 0.61±0.39...

Examination of Biodegradable Magnesium Screw Processed by Equal Channel Angular Pressing: A Novel In Vivo Study in Rabbits

Magnesium alloys have shown potential as biodegradable metallic materials for oral and maxillofacial surgery applications due to their degradability. Biodegradable magnesium are advantageous over existing biodegradable materials such as polymers, ceramics and bioactive glasses in load-bearing applications where sufficient strength and Young’s modulus close to that of the bone are required.

Preliminary Study of 2D Fracture Upscaling of Geothermal Rock Using IFS Fractal Model

Fractured rock plays important role in reservoir production. In larger scale, fractures are more likely to be heterogeneous and considered to be fractal in its nature. One of the characteristics of fractal structure is the scale independence. An investigation of fractal properties on natural fractured rock is therefore needed for modelling larger fracture. We have investigated the possibilities of fractal upscaling method to produce a larger geothermal fracture model based on smaller fracture data. We generate Iterated Function System (IFS) fractal model using parameters e.g. scale factor, angle between branch, initial line direction, and branch thickness. All the model parameters are obtained from smaller fracture data. We generate higher iteration model to be compared with larger geothermal fracture. The similarity between the IFS fractal model and natural fracture is measured by 2D box counting fractal dimension (D). The fractal dimension of first to fourth generation fractal model is (1.86 ± 0.02). The fractal dimension of the reference geothermal site is (1.86 ± 0.04). Besides of D, we found significant similarity of fracture parameters there are intensity and density between fracture model and natural fracture. Based on these result, we conclude that fractal upscaling using IFS fractal model is potential to model larger scale of 2D fracture.

Permeability Estimation of Porous Rock by Means of Fluid Flow Simulation and Digital Image Analysis

Permeability plays an important role to determine the characteristics of how fluids flow through a porous medium which can be estimated using various methods. Darcys law and the Kozeny-Carman equation are two of the most utilized methods in estimating permeability. In Darcys law, permeability can be calculated by applying a pressure gradient between opposing sides of inlet-outlet of a certain direction. The permeability then depends on the fluid viscosity and the flowrate. The Kozeny-Carman equation is an empirical equation which depends on several parameters such as shape factor of the pore, tortuosity, specific surface area, and porosity to determine the permeability. For both methods, digital image obtained by means of Micro CT-Scan is used. In this research, the permeability estimation using the Darcys law was conducted by simulating fluid flow through the digital image using Lattice Boltzmann Method (LBM). As for the Kozeny-Carman equation, digital image analysis was used to obtain the required parameters. Two Kozeny-Carman equations were used to calculate the permeability of the samples. The first equation (KC1) depends on pore shape factor, porosity, tortuosity, and specific surface area while the second equation (KC2) only depends on pore radius, porosity, and tortuosity. We investigate the methods by first testing on three simple pipe models which vary in the radii. By using the result from Darcys law as a reference, we compare the results from the Kozeny-Carman equations. From the calculation, KC2 yield smaller difference to the reference. The three methods were then applied to the Fontainebleau sandstone to verify the previous result.