Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 20... more Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE Asia Pacific Oil and Gas Conference and Exhibition held in Jakarta, Indonesia, 46 August 2009. This paper was selected for presentation by an SPE ...
Telah dilakukan studi analisis pori pada material nanopori dengan menggunakan metoda pengolahan c... more Telah dilakukan studi analisis pori pada material nanopori dengan menggunakan metoda pengolahan citra. Pengolahan citra dilakukan pada citra SEM dengan memanfaatkan aplikasi toolbox yang terdapat pada perangkat lunak Matlab. Melalui toolbox ini dapat ditentukan besarnya ukuran pori dan porositas yang terdapat pada citra SEM. Didapatkan bahwa distribusi ukuran pori dalam skala mikrometer sampai nanometer. Hasil studi menunjukkan bahwa pengolahan citra cocok untuk diterapkan pada karakterisasi material nanopori.
... distribusinya. Radius pori dapat diperoleh dengan bantuan pemrosesan citra digital. Dengan me... more ... distribusinya. Radius pori dapat diperoleh dengan bantuan pemrosesan citra digital. Dengan mendefinisikan radius pori sebagai rasio antara luas dan keliling pori citra, maka distribusi radius pori sebuah citra dapat dibuat. ...
Pendahuluan Simulasi yang penulis gunakan dalam peneltian menggunakan metode Lattice Boltzmann. S... more Pendahuluan Simulasi yang penulis gunakan dalam peneltian menggunakan metode Lattice Boltzmann. Sebelum melakukan pemodelan, penulis melakukan studi literatur mengenai teori aliran fluida[1-3] dan dasar dari LB[4-6], mempelajari penerapan metode LB dalam berbagai kasus[7-12], terutama dalam penerapan di aliran fluida multifasa. Kemudian penulis menyusun model dengan menggunakan LBM model Shan-Chen [13] dalam memodelkan aliran fluida multifasa. Simulasi yang dibuat divalidasi dengan teori analitik yang menjelaskan peristiwa aliran [14-15]. Kemudian penerapan model Shan-Chen dalam menjelaskan aliran fluida dalam pori batuan [16]. Berkaitan dengan studi literatur telah dilakukan, penelitian dilakukan dengan menggunakan model yang disusun sesuai kajian teori dan pengamatan yang dilakukan dalam peristiwa fisis. Penelitian yang dilakukan akan dijelaskan dalam bagian Model serta hasilnya akan dibicarakan dalam bagian Hasil dan diskusi
Microgeometry of two dimensional Random Sierspinski Carpets (RSCs) is analyzed. Twelve models of ... more Microgeometry of two dimensional Random Sierspinski Carpets (RSCs) is analyzed. Twelve models of 2D-RSCs with the same porosity and fractal dimension but three kind pore size distributions are investigated. We estimate the porosity (φ), specific surface area (s) and hydraulic diameter (D H) of the models from the concept of two point correlation functions. We also estimate the entropy length (L*) from concept of local porosity distribution and local geometry entropies. The porosities estimated using the correlation functions agree with the calculated porosities. The estimated mean pore diameter (r c) generally agree with average (mean) side length of pores (L).The hydraulic diameters (D H) for all models are larger than estimated pore diameters (r c). Each four models which have the same pore size distribution have similar local porosity distribution and almost have the same trend of entropy function but not similar. The entropy lengths (L*) of the first four models are 15, 14, 15 a...
Effective pressure can change the pore aspect ratio spectrum either elastically or irreversibly. ... more Effective pressure can change the pore aspect ratio spectrum either elastically or irreversibly. When the amount of change is not drastic, the opening or closing of existent cracks occurs, leading to a change in dry elastic moduli. At high effective pressure, most cracks are closed and little change is expected in response to effective pressure change. In addition, at high porosity, effective pressure may not play as significant a role due to the decreasing effect of cracks on elastic moduli. Therefore, the change in effective pressure strongly influences the dry elastic moduli only for reservoir rocks of low high porosity at low effective pressure. When the amount of change in effective pressure is substantial, the decrease may generate hydraulic fractures, greatly decreasing dry elastic moduli, and the increase may crush grains, decreasing porosity and consequently increasing dry elastic moduli considerably. In this paper we examine the empirical equations to model the rate of cha...
Three-dimensional reconstruction of porous rock using the Pigeon Hole model has been carried out ... more Three-dimensional reconstruction of porous rock using the Pigeon Hole model has been carried out to study flow properties of rocks. Flow properties (tortuosity and permeability) are investigated for created models. Qualitative flow characteristic shows that the samples are percolating well in the value of local porosity just about the value of the global porosity. Tortuosity is calculated using the Lattice Boltzmann Method. Tortuosity obtained for created models are in the range of 1.6341-2.5052. Permeability is calculated using Kozeny-Carman formula. Permeability of the models is about 0.4553 -146.0226. Permeability follows increasing exponentially as a function of porosity.
The existence of crack-type pore spaces in geothermal reservoir rock is considered significant be... more The existence of crack-type pore spaces in geothermal reservoir rock is considered significant because of the ability to transport fluids such as water vapour. Various 2D characterizations of cracks have been developed in the past. In recent decades, the development of imaging techniques has enabled better understanding of the nature of these cracks. Micro-CT was used in this research to obtain 3D images of geothermal reservoir rock from West Java. The reconstructed digital images of the sample had spatial resolution of 59.85 μm/pixel. 2D and 3D display of the digital samples was conducted using software. Various image processing techniques are widely available to characterize the digital data of the sample. Our analysis found values of total porosity to be 6.27% and volume fraction of the cracks at 2.79%. It is concluded that the existence of cracks in the pore space provides a significant means of transporting fluid in the sample.
Physica A: Statistical Mechanics and its Applications, 2010
A stochastic geometrical modeling technique is used to reconstruct a laboratory scale Fontaineble... more A stochastic geometrical modeling technique is used to reconstruct a laboratory scale Fontainebleau sandstone with a sidelength of 1.5 cm. The model reconstruction is based on crystallite properties and diagenetic parameters determined from two-dimensional images. The three-dimensional pore scale microstructure of the sandstone is represented by a list of quartz crystallites defined geometrically and placed in the continuum. This allows generation of synthetic µ-CT images of the rock model at arbitrary resolutions. Quantitative microstructure comparison based on Minkowski functionals, two-point correlation function and local porosity theory indicates that this modeling technique can provide more realistic and accurate models of sandstones than many existing techniques used currently.
ABSTRACT We investigated the mineral-magnetic behavior of sediments from Lake Towuti located in t... more ABSTRACT We investigated the mineral-magnetic behavior of sediments from Lake Towuti located in the Eastern Sulawesi Ophiolite belt, Indonesia. Rock magnetic analysis supplemented by X-ray diffraction and scanning electron microscopy analysis were performed on sediment core TOW10-9B from the north basin of Lake Towuti to give insights on the environmental and sedimentary processes controlling the magnetic properties of the sediment and its paleoclimatic significance. The results show that the core has three distinct zones of varying magnetic properties. Careful examination demonstrates that these zones correspond to varying levels of iron oxide dissolution and magnetite precipitation that are climatically and environmentally dependent. The magnetically strongest zone is characterized by weak iron oxide dissolution and intense magnetite precipitation, likely driven by changes in the stratification and/or water level of the lake during dry conditions in Marine Isotope Stage 2 (MIS2) period, whereas the two magnetically weaker zones are characterized by signs of dissolution and correspond to relatively wet conditions, respectively, during Marine Isotope Stage 3 (MIS3) and the Holocene. Although our data show that major changes in concentration dependent parameters, such as magnetic susceptibility and saturation isothermal remanent magnetization (SIRM), in Lake Towuti sediment correlate with changes in regional rainfall, many of the concentration changes are more strongly affected by in situ chemical processes than by changes in erosion and terrestrial sediment supply. These findings urge caution in the interpretation of magnetic mineral concentration profiles as indicators of clastic sediment inputs.
ABSTRACT Weighting particular grain in granular pile can change the stability of the pile. In nat... more ABSTRACT Weighting particular grain in granular pile can change the stability of the pile. In nature this weighting process is performed by increasing of water content due to rain or by agglomeration of several smaller grains into a larger one due to soil pressure. Four horizontal layers of hexagonal-packed grains are used in this simulation accompanied by one vertical layer acts as the left wall. From those four horizontal layers the lowest layer is defined as the floor. The left wall and the floor layers consist of fixed grains, while the other three layers are filled with movable grains. In the most top horizontal layer a particular grain is subjected to weighting process. It has been observed that during 200 s simulation time a micro-lanslide can occur if the minimum weighting is about 96 times of the original mass of the grain. As the weighting increasing the time needed for the micro-lanslide to emerge is decreasing. The position of the weighted grain is also play a role in introducing a micro-lanslide, the nearer the grain to the left wall the larger the time needed for the micro-lanslide to occur.
ABSTRACT In the last decade, reconstruction of porous rock as well as its modelling has been deve... more ABSTRACT In the last decade, reconstruction of porous rock as well as its modelling has been developed vastly, which has been possible because of the μCT scanning devices. One of a famous rock that has been a subject of many researches in the characterization of porous medium is the Fontainebleau sandstone. Its homogeneity of the pore structure has been one of the reasons of the development of computational analyses that have also been applied to characterize the rock. The characteristics include porosity, permeability, curvature, pore connectivity, and percolation. Many models have also been developed based on the properties of this rock, e.g., the Gaussian Field model, Diagenesis model, Simulated Annealing model and Continuum Geometrical model. In this paper we are interested in the characteristic of the pore geometry of Fontainebleau and its models, i.e., the quantification of pore shape. We performed analysis based on Fourier Descriptor, which utilized Complex Fourier analysis where the boundary of the 2D pore is circumnavigated in the complex plane, such as to obtain the shape boundary coordinates of an object. The analysis using Fourier Descriptors demonstrates that the complexity level can be distinguished using the extracted length characteristic of the shape signature, i.e., the higher the level of complexity, the higher the length characteristic of shape signature. From this analysis we conclude that the Continuum Geometrical model has the most similar pore geometry characteristics with the Fontainebleau sandstone.
ABSTRACT In this research, 3D computer models of laminated sandstone were generated. The grain si... more ABSTRACT In this research, 3D computer models of laminated sandstone were generated. The grain size and the thickness of the laminated layer were varied to identify the most significant feature of the layer. Characterizations of the flow properties were conducted by means of the local percolation probability, tortuosity and permeability. The variation of the laminae thickness yielded clearer effect compared to the variation of the grain size of the laminae. Quantitative analyses using tortuosity and permeability demonstrated that the greater the thickness of the laminated layer will increase the tortuosity and decrease the permeability.
International Journal of Rock Mechanics and Mining Sciences, 2012
ABSTRACT Increasing interest in physical properties of rocks for purposes such as reservoir engin... more ABSTRACT Increasing interest in physical properties of rocks for purposes such as reservoir engineering and environmental geophysics has stimulated increased use of computer modeling of rock microstructure. Three-dimensional rock microstructure models based on spherical and non-spherical grain models are presented in this paper. The models are used to calculate the permeability. Important parameters such as tortuosity, which is difficult to measure in the laboratory, can be calculated easily by means of Lattice Boltzmann Method applied to the constructed models. The Kozeny–Carman formula gives lower prediction than the measured permeability. Modified power laws of porosity give better estimates if divided into two separate formulas, one for porosities lower than 20% and another for porosities higher than 25%. This new empirical formula gives better prediction for all models, except pigeon-hole.
Estimation of permeability from image sections can be conducted by means of Local Porosity Theory... more Estimation of permeability from image sections can be conducted by means of Local Porosity Theory (LPT) and the effective medium approximation (EMA). Using these approaches, the coordination number that is important for rock modeling is included. In this paper, we extend the EMA approach by considering the percolation probability as an additional parameter. Both equations show that permeability will be higher as coordination number as well as percolation probability increases. The permeability increases most rapidly close to the percolation threshold. Several thin sections of sandstone were created by digital image analysis. Two Point Correlation Functions were applied to estimate porosity and specific surface area. Permeability distribution as an input to EMA was created from the local permeability. The effective permeability was then calculated from the EMA equation iteratively. The result shows that considering coordination number and percolation probability will improve permeability estimation.
Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 20... more Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE Asia Pacific Oil and Gas Conference and Exhibition held in Jakarta, Indonesia, 46 August 2009. This paper was selected for presentation by an SPE ...
Telah dilakukan studi analisis pori pada material nanopori dengan menggunakan metoda pengolahan c... more Telah dilakukan studi analisis pori pada material nanopori dengan menggunakan metoda pengolahan citra. Pengolahan citra dilakukan pada citra SEM dengan memanfaatkan aplikasi toolbox yang terdapat pada perangkat lunak Matlab. Melalui toolbox ini dapat ditentukan besarnya ukuran pori dan porositas yang terdapat pada citra SEM. Didapatkan bahwa distribusi ukuran pori dalam skala mikrometer sampai nanometer. Hasil studi menunjukkan bahwa pengolahan citra cocok untuk diterapkan pada karakterisasi material nanopori.
... distribusinya. Radius pori dapat diperoleh dengan bantuan pemrosesan citra digital. Dengan me... more ... distribusinya. Radius pori dapat diperoleh dengan bantuan pemrosesan citra digital. Dengan mendefinisikan radius pori sebagai rasio antara luas dan keliling pori citra, maka distribusi radius pori sebuah citra dapat dibuat. ...
Pendahuluan Simulasi yang penulis gunakan dalam peneltian menggunakan metode Lattice Boltzmann. S... more Pendahuluan Simulasi yang penulis gunakan dalam peneltian menggunakan metode Lattice Boltzmann. Sebelum melakukan pemodelan, penulis melakukan studi literatur mengenai teori aliran fluida[1-3] dan dasar dari LB[4-6], mempelajari penerapan metode LB dalam berbagai kasus[7-12], terutama dalam penerapan di aliran fluida multifasa. Kemudian penulis menyusun model dengan menggunakan LBM model Shan-Chen [13] dalam memodelkan aliran fluida multifasa. Simulasi yang dibuat divalidasi dengan teori analitik yang menjelaskan peristiwa aliran [14-15]. Kemudian penerapan model Shan-Chen dalam menjelaskan aliran fluida dalam pori batuan [16]. Berkaitan dengan studi literatur telah dilakukan, penelitian dilakukan dengan menggunakan model yang disusun sesuai kajian teori dan pengamatan yang dilakukan dalam peristiwa fisis. Penelitian yang dilakukan akan dijelaskan dalam bagian Model serta hasilnya akan dibicarakan dalam bagian Hasil dan diskusi
Microgeometry of two dimensional Random Sierspinski Carpets (RSCs) is analyzed. Twelve models of ... more Microgeometry of two dimensional Random Sierspinski Carpets (RSCs) is analyzed. Twelve models of 2D-RSCs with the same porosity and fractal dimension but three kind pore size distributions are investigated. We estimate the porosity (φ), specific surface area (s) and hydraulic diameter (D H) of the models from the concept of two point correlation functions. We also estimate the entropy length (L*) from concept of local porosity distribution and local geometry entropies. The porosities estimated using the correlation functions agree with the calculated porosities. The estimated mean pore diameter (r c) generally agree with average (mean) side length of pores (L).The hydraulic diameters (D H) for all models are larger than estimated pore diameters (r c). Each four models which have the same pore size distribution have similar local porosity distribution and almost have the same trend of entropy function but not similar. The entropy lengths (L*) of the first four models are 15, 14, 15 a...
Effective pressure can change the pore aspect ratio spectrum either elastically or irreversibly. ... more Effective pressure can change the pore aspect ratio spectrum either elastically or irreversibly. When the amount of change is not drastic, the opening or closing of existent cracks occurs, leading to a change in dry elastic moduli. At high effective pressure, most cracks are closed and little change is expected in response to effective pressure change. In addition, at high porosity, effective pressure may not play as significant a role due to the decreasing effect of cracks on elastic moduli. Therefore, the change in effective pressure strongly influences the dry elastic moduli only for reservoir rocks of low high porosity at low effective pressure. When the amount of change in effective pressure is substantial, the decrease may generate hydraulic fractures, greatly decreasing dry elastic moduli, and the increase may crush grains, decreasing porosity and consequently increasing dry elastic moduli considerably. In this paper we examine the empirical equations to model the rate of cha...
Three-dimensional reconstruction of porous rock using the Pigeon Hole model has been carried out ... more Three-dimensional reconstruction of porous rock using the Pigeon Hole model has been carried out to study flow properties of rocks. Flow properties (tortuosity and permeability) are investigated for created models. Qualitative flow characteristic shows that the samples are percolating well in the value of local porosity just about the value of the global porosity. Tortuosity is calculated using the Lattice Boltzmann Method. Tortuosity obtained for created models are in the range of 1.6341-2.5052. Permeability is calculated using Kozeny-Carman formula. Permeability of the models is about 0.4553 -146.0226. Permeability follows increasing exponentially as a function of porosity.
The existence of crack-type pore spaces in geothermal reservoir rock is considered significant be... more The existence of crack-type pore spaces in geothermal reservoir rock is considered significant because of the ability to transport fluids such as water vapour. Various 2D characterizations of cracks have been developed in the past. In recent decades, the development of imaging techniques has enabled better understanding of the nature of these cracks. Micro-CT was used in this research to obtain 3D images of geothermal reservoir rock from West Java. The reconstructed digital images of the sample had spatial resolution of 59.85 μm/pixel. 2D and 3D display of the digital samples was conducted using software. Various image processing techniques are widely available to characterize the digital data of the sample. Our analysis found values of total porosity to be 6.27% and volume fraction of the cracks at 2.79%. It is concluded that the existence of cracks in the pore space provides a significant means of transporting fluid in the sample.
Physica A: Statistical Mechanics and its Applications, 2010
A stochastic geometrical modeling technique is used to reconstruct a laboratory scale Fontaineble... more A stochastic geometrical modeling technique is used to reconstruct a laboratory scale Fontainebleau sandstone with a sidelength of 1.5 cm. The model reconstruction is based on crystallite properties and diagenetic parameters determined from two-dimensional images. The three-dimensional pore scale microstructure of the sandstone is represented by a list of quartz crystallites defined geometrically and placed in the continuum. This allows generation of synthetic µ-CT images of the rock model at arbitrary resolutions. Quantitative microstructure comparison based on Minkowski functionals, two-point correlation function and local porosity theory indicates that this modeling technique can provide more realistic and accurate models of sandstones than many existing techniques used currently.
ABSTRACT We investigated the mineral-magnetic behavior of sediments from Lake Towuti located in t... more ABSTRACT We investigated the mineral-magnetic behavior of sediments from Lake Towuti located in the Eastern Sulawesi Ophiolite belt, Indonesia. Rock magnetic analysis supplemented by X-ray diffraction and scanning electron microscopy analysis were performed on sediment core TOW10-9B from the north basin of Lake Towuti to give insights on the environmental and sedimentary processes controlling the magnetic properties of the sediment and its paleoclimatic significance. The results show that the core has three distinct zones of varying magnetic properties. Careful examination demonstrates that these zones correspond to varying levels of iron oxide dissolution and magnetite precipitation that are climatically and environmentally dependent. The magnetically strongest zone is characterized by weak iron oxide dissolution and intense magnetite precipitation, likely driven by changes in the stratification and/or water level of the lake during dry conditions in Marine Isotope Stage 2 (MIS2) period, whereas the two magnetically weaker zones are characterized by signs of dissolution and correspond to relatively wet conditions, respectively, during Marine Isotope Stage 3 (MIS3) and the Holocene. Although our data show that major changes in concentration dependent parameters, such as magnetic susceptibility and saturation isothermal remanent magnetization (SIRM), in Lake Towuti sediment correlate with changes in regional rainfall, many of the concentration changes are more strongly affected by in situ chemical processes than by changes in erosion and terrestrial sediment supply. These findings urge caution in the interpretation of magnetic mineral concentration profiles as indicators of clastic sediment inputs.
ABSTRACT Weighting particular grain in granular pile can change the stability of the pile. In nat... more ABSTRACT Weighting particular grain in granular pile can change the stability of the pile. In nature this weighting process is performed by increasing of water content due to rain or by agglomeration of several smaller grains into a larger one due to soil pressure. Four horizontal layers of hexagonal-packed grains are used in this simulation accompanied by one vertical layer acts as the left wall. From those four horizontal layers the lowest layer is defined as the floor. The left wall and the floor layers consist of fixed grains, while the other three layers are filled with movable grains. In the most top horizontal layer a particular grain is subjected to weighting process. It has been observed that during 200 s simulation time a micro-lanslide can occur if the minimum weighting is about 96 times of the original mass of the grain. As the weighting increasing the time needed for the micro-lanslide to emerge is decreasing. The position of the weighted grain is also play a role in introducing a micro-lanslide, the nearer the grain to the left wall the larger the time needed for the micro-lanslide to occur.
ABSTRACT In the last decade, reconstruction of porous rock as well as its modelling has been deve... more ABSTRACT In the last decade, reconstruction of porous rock as well as its modelling has been developed vastly, which has been possible because of the μCT scanning devices. One of a famous rock that has been a subject of many researches in the characterization of porous medium is the Fontainebleau sandstone. Its homogeneity of the pore structure has been one of the reasons of the development of computational analyses that have also been applied to characterize the rock. The characteristics include porosity, permeability, curvature, pore connectivity, and percolation. Many models have also been developed based on the properties of this rock, e.g., the Gaussian Field model, Diagenesis model, Simulated Annealing model and Continuum Geometrical model. In this paper we are interested in the characteristic of the pore geometry of Fontainebleau and its models, i.e., the quantification of pore shape. We performed analysis based on Fourier Descriptor, which utilized Complex Fourier analysis where the boundary of the 2D pore is circumnavigated in the complex plane, such as to obtain the shape boundary coordinates of an object. The analysis using Fourier Descriptors demonstrates that the complexity level can be distinguished using the extracted length characteristic of the shape signature, i.e., the higher the level of complexity, the higher the length characteristic of shape signature. From this analysis we conclude that the Continuum Geometrical model has the most similar pore geometry characteristics with the Fontainebleau sandstone.
ABSTRACT In this research, 3D computer models of laminated sandstone were generated. The grain si... more ABSTRACT In this research, 3D computer models of laminated sandstone were generated. The grain size and the thickness of the laminated layer were varied to identify the most significant feature of the layer. Characterizations of the flow properties were conducted by means of the local percolation probability, tortuosity and permeability. The variation of the laminae thickness yielded clearer effect compared to the variation of the grain size of the laminae. Quantitative analyses using tortuosity and permeability demonstrated that the greater the thickness of the laminated layer will increase the tortuosity and decrease the permeability.
International Journal of Rock Mechanics and Mining Sciences, 2012
ABSTRACT Increasing interest in physical properties of rocks for purposes such as reservoir engin... more ABSTRACT Increasing interest in physical properties of rocks for purposes such as reservoir engineering and environmental geophysics has stimulated increased use of computer modeling of rock microstructure. Three-dimensional rock microstructure models based on spherical and non-spherical grain models are presented in this paper. The models are used to calculate the permeability. Important parameters such as tortuosity, which is difficult to measure in the laboratory, can be calculated easily by means of Lattice Boltzmann Method applied to the constructed models. The Kozeny–Carman formula gives lower prediction than the measured permeability. Modified power laws of porosity give better estimates if divided into two separate formulas, one for porosities lower than 20% and another for porosities higher than 25%. This new empirical formula gives better prediction for all models, except pigeon-hole.
Estimation of permeability from image sections can be conducted by means of Local Porosity Theory... more Estimation of permeability from image sections can be conducted by means of Local Porosity Theory (LPT) and the effective medium approximation (EMA). Using these approaches, the coordination number that is important for rock modeling is included. In this paper, we extend the EMA approach by considering the percolation probability as an additional parameter. Both equations show that permeability will be higher as coordination number as well as percolation probability increases. The permeability increases most rapidly close to the percolation threshold. Several thin sections of sandstone were created by digital image analysis. Two Point Correlation Functions were applied to estimate porosity and specific surface area. Permeability distribution as an input to EMA was created from the local permeability. The effective permeability was then calculated from the EMA equation iteratively. The result shows that considering coordination number and percolation probability will improve permeability estimation.
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