Water channeling is caused by reservoir heterogeneities that lead to the development of high-perm... more Water channeling is caused by reservoir heterogeneities that lead to the development of high-permeability streaks. A recent interest in microgel treatment using preformed particle gels (PPGs) has drawn more attention to reducing excess water production, improving sweep efficiency, and enhancing macroscopic oil recovery. The objective of this paper is to gain an inclusive understanding of PPG transport mechanisms through heterogeneous reservoirs. A numerical simulator was developed to characterize the propagation of PPGs through given reservoir. The simulator was used to optimize the gel treatment design to enhance oil recovery from un-swept, low-permeability, and oil-rich zones. A novel core flooding experiment was conducted to validate the developed mechanistic models. The experimental results using heterogeneous permeability model without cross flow showed large incremental oil recovery from the low permeability sand pack after treatment with PPGs. The developed models were implemented into the gel transport reservoir simulator to aid in the design and to optimize the water control processes using PPGs. The results obtained from the simulator indicated a good match with core flooding experiment results. The sensitivity analysis showed incremental oil recovery was strongly dependent on the permeability contrast, PPG concentration, and PPG treatment size.
Despite the importance of perceived barriers against self-care in diabetic patients, the role of ... more Despite the importance of perceived barriers against self-care in diabetic patients, the role of this factor is rarely addressed in the improvement of self-care behaviors of Iranian patients. The lack of appropriate instruments that fit demographic properties of Iranian society is one reason. The aim of this study was to develop and validate the scale of perceived barriers to self-care in patients with type 2 diabetes mellitus. This cross-sectional study conducted on 400 patients with type 2 diabetes who were covered by the health centers in Isfahan (Iran) in 2015. A 22-item, researcher-made instrument was designed; the face and content validities of the instrument were examined through obtaining the opinions of an expert panel before administering the instrument in the study. Also, the exploratory factor analysis was used to investigate the instrument's validity. Cronbach's alpha was employed to measure its internal consistency (reliability). To examine the validity of the final scale, the mean scores of perceived barriers in patients with appropriate and inappropriate self-care behaviors were compared. The research sample was comprised of 240 women (60%) and 160 men (40%). The mean value of the content validity index was 0.84. The results of factor analysis confirmed the validity of the 11 items and 3 factors of the developed scale. The factor loading ranged from 0.46 to 0.78. These three factors together explained 40.28% of the total variance. The overall reliability coefficient of the instrument was 0.79, ranging from 0.82 to 0.93 for three factors. According to the results, the developed scale was a valid and reliable instrument for examining the barriers perceived by the patients. The findings of this research can help health policy makers in planning to facilitate the self-care behaviors as the most vital factor in diabetes control.
ABSTRACT Ground Penetrating Radar or GPR is based on the reflection of electromagnetic waves from... more ABSTRACT Ground Penetrating Radar or GPR is based on the reflection of electromagnetic waves from the boundaries accompanied by change of their dielectric properties. GPR is a geophysical method with high resolution. In this method is used from high frequency electromagnetic waves (12.5 to 2300 MHz) to detect subsurface structures. One of the problems in GPR is demolition by environmental noises. This article has studied on success of using 2-D dual-tree complex wavelet transform (2-D DTCWT) on processed GPR data than the usual method of 2-D Fourier transform.
Seg Technical Program Expanded Abstracts, Aug 17, 2012
ABSTRACT Presence of noise on shot gathers has very hazardous effect on seismic data processing. ... more ABSTRACT Presence of noise on shot gathers has very hazardous effect on seismic data processing. Many scientists have attempted to attenuate noise without damaging the signal. The goal of this study is to use a new DWT technique for seismic coherent noise attenuation. For this purpose, Rational-Dilation Wavelet Transforms (RDWT) was used as an algorithm to remove ground roll from reflection seismic data. The rational dilation DWT has advantages that the user can tune the transform to acquire better time section. The advantages of the method are: firstly, the redundancy factor can vary due to the processing in traces and along the time and secondly, Q-factor should be selected to control the speed of the transform and let the user to choose the best parameter of Q. This method overcomes the Fourier transform restrictions and has time run less than the f-k method. The results of this research showed that the continuity of the events was enhanced, and noises were attenuated well.
Stenting is one of the most important methods to treat atherosclerosis. Due to its simplicity and... more Stenting is one of the most important methods to treat atherosclerosis. Due to its simplicity and efficiency, the use of coronary stents in interventional procedures has rapidly increased, and different stent designs have been introduced in the market. In order to select the most appropriate stent design, it is necessary to analyze and compare the mechanical behavior of different types of stents. In this paper, the finite element method is used for analyzing the behavior of stents. The aim of this work is to investigate the expansion characteristics of a stent as it is deployed and implanted in an artery containing a plaque and propose a model as close to real conditions of stent implantation as possible. Furthermore, two commercially available stents (the Palmaz-Schatz and Multi-Link stents) are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and dogboning. Moreover, the effect of stent design on the ...
This study evaluated the effects of exogenous cyclic GMP (cGMP) and cyclic AMP (cAMP) on motion p... more This study evaluated the effects of exogenous cyclic GMP (cGMP) and cyclic AMP (cAMP) on motion parameters of epididymal ram sperm in vitro. After incubation of epididymal sperm samples for 45 and 90 min in the presence of 8-Br-cAMP (0.5, 5, and 50 mM) and 8-Br-cGMP (0.01, 0.1, and 1 mM), motion parameters were evaluated by computer-aided sperm analysis. At 0.5 mM concentration of 8-Br-cAMP, there was a significant increase in amplitude of lateral head displacement (ALH; at 45 min), curvilinear velocity (VCL; at 90 min), and mean angle of deviation (MAD; at 90 min) of sperm while a decrease in the beat cross frequency (BCF; at 45 min) in cAMP-treated groups was observed. At 5 mM 8-Br-cAMP, there was a significant increase in VCL (at 45 and 90 min), straight line velocity (VSL), average path velocity (VAP),MAD, ALH, linearity (LIN), and straightness (STR; at 45 min) of sperm but decreasing BCF (at 45 and 90 min) and wobble (at 90 min) in cAMP-treated groups compared to controls. At 5...
Journal of Surface Engineered Materials and Advanced Technology, 2011
Each surface of roughness has different shape of asperity which is modeled with various shapes of... more Each surface of roughness has different shape of asperity which is modeled with various shapes of analytical models. In this paper, the differences among various models of shape of asperity investigate using the Finite Element Method (FEM) and various analytical models. The contact stresses in rough surfaces are calculated analytically using various asperity shape models. Finite element analysis is also carried out assuming three types of material properties namely, the linear, the elastic-perfect plastic and the elastic-nonlinear hardening. The analytical results are compared with the results obtained by the finite element method. The results illustrate for using a deterministic approach which the numerical models are suitable. In hertz model, the result of force is very big in interface of causing deformation plastic, while Model Zhao has almost same result with FEM nonlinear property model. It is observed that the results obtained from Zhao's model are generally in a better agreement with the results obtained from various finite element models especially in elastic-plastic and plastic zones, hence it may be concluded that Zhao's model can be used for analyzing the rough surfaces in contact mechanics.
Journal of Petroleum Science and Engineering, 2014
Water floods are often very inefficient in naturally fractured carbonate oil reservoirs because m... more Water floods are often very inefficient in naturally fractured carbonate oil reservoirs because many of these reservoirs are mixed-wet or oil-wet as well as extremely heterogeneous. Naturally fractured reservoirs are challenging targets for chemical flooding because they typically have a high permeability contrast between the fractures and the matrix with a low matrix permeability. Some of the world's largest oil reservoirs are fractured carbonates with a high reservoir temperature and a high salinity formation brine. Some of them also have low API gravity oils, which also increases the difficulty of recovering the oil. A surfactant formulation has been developed that shows promising results for such difficult reservoirs. Ultra-low interfacial tension (IFT) and good aqueous stability were achieved with this new carboxylate surfactant in a hard brine at a high reservoir temperature of 100 1C. Both static and dynamic imbibition experiments were conducted using a fractured carbonate core. 65.9% Oil recovery was obtained in fractured coreflood compared to 33.3% oil recovery in static imbibition test. The surfactant retention was low at 0.086 mg/g of rock. The oil recovery is excellent taking into account that the temperature and salinity conditions were harsh, the core was extremely vuggy and fractured, no mobility control was used, and only a small surfactant slug was injected. The coreflood results were interpreted using a mechanistic chemical reservoir simulator. It showed that both the mechanisms of IFT reduction and wettability alteration were important for oil recovery. Neither IFT reduction nor wettability alteration alone recovered oil as high as the combined contributions from both.
Journal of Petroleum Science and Engineering, 2015
Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to th... more Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to the commonly oil-wet nature of these rocks and the lack of sufficient spontaneous capillary imbibition driving force to push oil out from the matrix to the fracture network. Chemical processes such as surfactant/alkali-induced wettability alteration and interfacial tension (IFT) reduction have shown great potential to reduce the residual oil saturation in matrix blocks, leading to significant incremental oil recovery (IOR). However, the time required to achieve a significant amount of oil recovery is the most crucial deciding factor in field projects. The magnitude of recovery and response time of any chemical process depends on the degree of wettability alteration and IFT reduction, the nature and density of fracture network, and the matrix block size.
SPE Annual Technical Conference and Exhibition, 2012
Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to th... more Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to the commonly oil-wet nature of these rocks and the lack of sufficient spontaneous capillary imbibition driving force to push oil out from the matrix to the fracture network. Chemical processes such as surfactant/alkali-induced wettability alteration and interfacial tension (IFT) reduction have shown great potential to reduce the residual oil saturation in matrix blocks, leading to significant incremental oil recovery (IOR). However, the IOR response time is the most crucial decision factor in field projects. The magnitude and time efficiency of recovery depend on the degree of wettability alteration and IFT reduction, the nature and density of fracture network, and the dimensions of matrix blocks.
Excess water production is a major problem that leads to early well abandonment and unrecoverable... more Excess water production is a major problem that leads to early well abandonment and unrecoverable hydrocarbon in mature oil fields. Gel treatments at the injection wells to preferentially plug the thief zones are cost-effective methods to improve sweep efficiency in reservoirs and reduce excess water production during hydrocarbon recovery. A recent gel process uses the preformed particle gels (PPGs) to overcome distinct drawbacks inherent in in-situ gelation systems, i.e. lack of control on gelation time, uncertain gelling due to shear degradation, chromatographic fractionation or change of gel compositions, and dilution by formation water. This paper describes the results of PPG injection in both fracture and sandpack models where the experimental results were used to develop and validate mechanistic models to design and optimize the flowing gel injection for conformance control processes. Crucial properties gel such as in-situ rheology and swelling ratio in addition to oil recoveries were investigated. The water and oil permeability reduction factors were measured and modeled as a function of gel strength, rock permeability, and flow rate. The PPG transport models were successfully implemented in a reservoir simulator and validated against the laboratory experiments.
International Universities Power Engineering Conference, 2004
Metal oxide surge arresters (MOSA) are widely used as protective devices against switching and li... more Metal oxide surge arresters (MOSA) are widely used as protective devices against switching and lightning overvoltages in electrical power systems. Appropriate modeling of their dynamic characteristics is very important for insulation coordination, arrester location and energy absorption studies. Working group 3.4.11 of IEEE has recommended a model that can be used in the range of current surge wave front time
PPG experiments in both fracture and sandpack were successfully performed. PPG experiments rank t... more PPG experiments in both fracture and sandpack were successfully performed. PPG experiments rank the effect of PPG on improving conformance. We have developed mathematical models for gel rheology, adsorption, swelling ratio. The gel transport models were implemented in a reservoir simulator (UTGEL). The UTGEL simulator was validated against laboratory experiments.
Water channeling is caused by reservoir heterogeneities that lead to the development of high-perm... more Water channeling is caused by reservoir heterogeneities that lead to the development of high-permeability streaks. A recent interest in microgel treatment using preformed particle gels (PPGs) has drawn more attention to reducing excess water production, improving sweep efficiency, and enhancing macroscopic oil recovery. The objective of this paper is to gain an inclusive understanding of PPG transport mechanisms through heterogeneous reservoirs. A numerical simulator was developed to characterize the propagation of PPGs through given reservoir. The simulator was used to optimize the gel treatment design to enhance oil recovery from un-swept, low-permeability, and oil-rich zones. A novel core flooding experiment was conducted to validate the developed mechanistic models. The experimental results using heterogeneous permeability model without cross flow showed large incremental oil recovery from the low permeability sand pack after treatment with PPGs. The developed models were implemented into the gel transport reservoir simulator to aid in the design and to optimize the water control processes using PPGs. The results obtained from the simulator indicated a good match with core flooding experiment results. The sensitivity analysis showed incremental oil recovery was strongly dependent on the permeability contrast, PPG concentration, and PPG treatment size.
Despite the importance of perceived barriers against self-care in diabetic patients, the role of ... more Despite the importance of perceived barriers against self-care in diabetic patients, the role of this factor is rarely addressed in the improvement of self-care behaviors of Iranian patients. The lack of appropriate instruments that fit demographic properties of Iranian society is one reason. The aim of this study was to develop and validate the scale of perceived barriers to self-care in patients with type 2 diabetes mellitus. This cross-sectional study conducted on 400 patients with type 2 diabetes who were covered by the health centers in Isfahan (Iran) in 2015. A 22-item, researcher-made instrument was designed; the face and content validities of the instrument were examined through obtaining the opinions of an expert panel before administering the instrument in the study. Also, the exploratory factor analysis was used to investigate the instrument's validity. Cronbach's alpha was employed to measure its internal consistency (reliability). To examine the validity of the final scale, the mean scores of perceived barriers in patients with appropriate and inappropriate self-care behaviors were compared. The research sample was comprised of 240 women (60%) and 160 men (40%). The mean value of the content validity index was 0.84. The results of factor analysis confirmed the validity of the 11 items and 3 factors of the developed scale. The factor loading ranged from 0.46 to 0.78. These three factors together explained 40.28% of the total variance. The overall reliability coefficient of the instrument was 0.79, ranging from 0.82 to 0.93 for three factors. According to the results, the developed scale was a valid and reliable instrument for examining the barriers perceived by the patients. The findings of this research can help health policy makers in planning to facilitate the self-care behaviors as the most vital factor in diabetes control.
ABSTRACT Ground Penetrating Radar or GPR is based on the reflection of electromagnetic waves from... more ABSTRACT Ground Penetrating Radar or GPR is based on the reflection of electromagnetic waves from the boundaries accompanied by change of their dielectric properties. GPR is a geophysical method with high resolution. In this method is used from high frequency electromagnetic waves (12.5 to 2300 MHz) to detect subsurface structures. One of the problems in GPR is demolition by environmental noises. This article has studied on success of using 2-D dual-tree complex wavelet transform (2-D DTCWT) on processed GPR data than the usual method of 2-D Fourier transform.
Seg Technical Program Expanded Abstracts, Aug 17, 2012
ABSTRACT Presence of noise on shot gathers has very hazardous effect on seismic data processing. ... more ABSTRACT Presence of noise on shot gathers has very hazardous effect on seismic data processing. Many scientists have attempted to attenuate noise without damaging the signal. The goal of this study is to use a new DWT technique for seismic coherent noise attenuation. For this purpose, Rational-Dilation Wavelet Transforms (RDWT) was used as an algorithm to remove ground roll from reflection seismic data. The rational dilation DWT has advantages that the user can tune the transform to acquire better time section. The advantages of the method are: firstly, the redundancy factor can vary due to the processing in traces and along the time and secondly, Q-factor should be selected to control the speed of the transform and let the user to choose the best parameter of Q. This method overcomes the Fourier transform restrictions and has time run less than the f-k method. The results of this research showed that the continuity of the events was enhanced, and noises were attenuated well.
Stenting is one of the most important methods to treat atherosclerosis. Due to its simplicity and... more Stenting is one of the most important methods to treat atherosclerosis. Due to its simplicity and efficiency, the use of coronary stents in interventional procedures has rapidly increased, and different stent designs have been introduced in the market. In order to select the most appropriate stent design, it is necessary to analyze and compare the mechanical behavior of different types of stents. In this paper, the finite element method is used for analyzing the behavior of stents. The aim of this work is to investigate the expansion characteristics of a stent as it is deployed and implanted in an artery containing a plaque and propose a model as close to real conditions of stent implantation as possible. Furthermore, two commercially available stents (the Palmaz-Schatz and Multi-Link stents) are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and dogboning. Moreover, the effect of stent design on the ...
This study evaluated the effects of exogenous cyclic GMP (cGMP) and cyclic AMP (cAMP) on motion p... more This study evaluated the effects of exogenous cyclic GMP (cGMP) and cyclic AMP (cAMP) on motion parameters of epididymal ram sperm in vitro. After incubation of epididymal sperm samples for 45 and 90 min in the presence of 8-Br-cAMP (0.5, 5, and 50 mM) and 8-Br-cGMP (0.01, 0.1, and 1 mM), motion parameters were evaluated by computer-aided sperm analysis. At 0.5 mM concentration of 8-Br-cAMP, there was a significant increase in amplitude of lateral head displacement (ALH; at 45 min), curvilinear velocity (VCL; at 90 min), and mean angle of deviation (MAD; at 90 min) of sperm while a decrease in the beat cross frequency (BCF; at 45 min) in cAMP-treated groups was observed. At 5 mM 8-Br-cAMP, there was a significant increase in VCL (at 45 and 90 min), straight line velocity (VSL), average path velocity (VAP),MAD, ALH, linearity (LIN), and straightness (STR; at 45 min) of sperm but decreasing BCF (at 45 and 90 min) and wobble (at 90 min) in cAMP-treated groups compared to controls. At 5...
Journal of Surface Engineered Materials and Advanced Technology, 2011
Each surface of roughness has different shape of asperity which is modeled with various shapes of... more Each surface of roughness has different shape of asperity which is modeled with various shapes of analytical models. In this paper, the differences among various models of shape of asperity investigate using the Finite Element Method (FEM) and various analytical models. The contact stresses in rough surfaces are calculated analytically using various asperity shape models. Finite element analysis is also carried out assuming three types of material properties namely, the linear, the elastic-perfect plastic and the elastic-nonlinear hardening. The analytical results are compared with the results obtained by the finite element method. The results illustrate for using a deterministic approach which the numerical models are suitable. In hertz model, the result of force is very big in interface of causing deformation plastic, while Model Zhao has almost same result with FEM nonlinear property model. It is observed that the results obtained from Zhao's model are generally in a better agreement with the results obtained from various finite element models especially in elastic-plastic and plastic zones, hence it may be concluded that Zhao's model can be used for analyzing the rough surfaces in contact mechanics.
Journal of Petroleum Science and Engineering, 2014
Water floods are often very inefficient in naturally fractured carbonate oil reservoirs because m... more Water floods are often very inefficient in naturally fractured carbonate oil reservoirs because many of these reservoirs are mixed-wet or oil-wet as well as extremely heterogeneous. Naturally fractured reservoirs are challenging targets for chemical flooding because they typically have a high permeability contrast between the fractures and the matrix with a low matrix permeability. Some of the world's largest oil reservoirs are fractured carbonates with a high reservoir temperature and a high salinity formation brine. Some of them also have low API gravity oils, which also increases the difficulty of recovering the oil. A surfactant formulation has been developed that shows promising results for such difficult reservoirs. Ultra-low interfacial tension (IFT) and good aqueous stability were achieved with this new carboxylate surfactant in a hard brine at a high reservoir temperature of 100 1C. Both static and dynamic imbibition experiments were conducted using a fractured carbonate core. 65.9% Oil recovery was obtained in fractured coreflood compared to 33.3% oil recovery in static imbibition test. The surfactant retention was low at 0.086 mg/g of rock. The oil recovery is excellent taking into account that the temperature and salinity conditions were harsh, the core was extremely vuggy and fractured, no mobility control was used, and only a small surfactant slug was injected. The coreflood results were interpreted using a mechanistic chemical reservoir simulator. It showed that both the mechanisms of IFT reduction and wettability alteration were important for oil recovery. Neither IFT reduction nor wettability alteration alone recovered oil as high as the combined contributions from both.
Journal of Petroleum Science and Engineering, 2015
Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to th... more Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to the commonly oil-wet nature of these rocks and the lack of sufficient spontaneous capillary imbibition driving force to push oil out from the matrix to the fracture network. Chemical processes such as surfactant/alkali-induced wettability alteration and interfacial tension (IFT) reduction have shown great potential to reduce the residual oil saturation in matrix blocks, leading to significant incremental oil recovery (IOR). However, the time required to achieve a significant amount of oil recovery is the most crucial deciding factor in field projects. The magnitude of recovery and response time of any chemical process depends on the degree of wettability alteration and IFT reduction, the nature and density of fracture network, and the matrix block size.
SPE Annual Technical Conference and Exhibition, 2012
Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to th... more Oil recovery from fractured carbonate reservoirs by water flooding is often inefficient due to the commonly oil-wet nature of these rocks and the lack of sufficient spontaneous capillary imbibition driving force to push oil out from the matrix to the fracture network. Chemical processes such as surfactant/alkali-induced wettability alteration and interfacial tension (IFT) reduction have shown great potential to reduce the residual oil saturation in matrix blocks, leading to significant incremental oil recovery (IOR). However, the IOR response time is the most crucial decision factor in field projects. The magnitude and time efficiency of recovery depend on the degree of wettability alteration and IFT reduction, the nature and density of fracture network, and the dimensions of matrix blocks.
Excess water production is a major problem that leads to early well abandonment and unrecoverable... more Excess water production is a major problem that leads to early well abandonment and unrecoverable hydrocarbon in mature oil fields. Gel treatments at the injection wells to preferentially plug the thief zones are cost-effective methods to improve sweep efficiency in reservoirs and reduce excess water production during hydrocarbon recovery. A recent gel process uses the preformed particle gels (PPGs) to overcome distinct drawbacks inherent in in-situ gelation systems, i.e. lack of control on gelation time, uncertain gelling due to shear degradation, chromatographic fractionation or change of gel compositions, and dilution by formation water. This paper describes the results of PPG injection in both fracture and sandpack models where the experimental results were used to develop and validate mechanistic models to design and optimize the flowing gel injection for conformance control processes. Crucial properties gel such as in-situ rheology and swelling ratio in addition to oil recoveries were investigated. The water and oil permeability reduction factors were measured and modeled as a function of gel strength, rock permeability, and flow rate. The PPG transport models were successfully implemented in a reservoir simulator and validated against the laboratory experiments.
International Universities Power Engineering Conference, 2004
Metal oxide surge arresters (MOSA) are widely used as protective devices against switching and li... more Metal oxide surge arresters (MOSA) are widely used as protective devices against switching and lightning overvoltages in electrical power systems. Appropriate modeling of their dynamic characteristics is very important for insulation coordination, arrester location and energy absorption studies. Working group 3.4.11 of IEEE has recommended a model that can be used in the range of current surge wave front time
PPG experiments in both fracture and sandpack were successfully performed. PPG experiments rank t... more PPG experiments in both fracture and sandpack were successfully performed. PPG experiments rank the effect of PPG on improving conformance. We have developed mathematical models for gel rheology, adsorption, swelling ratio. The gel transport models were implemented in a reservoir simulator (UTGEL). The UTGEL simulator was validated against laboratory experiments.
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Papers by Ali Goudarzi