The ability of a novel nonionic CO2 -soluble surfactant to propagate foam in porous media was compared with that of a conventional anionic surfactant（aqueous soluble only）through core floods with Berea sandstone cor...The ability of a novel nonionic CO2 -soluble surfactant to propagate foam in porous media was compared with that of a conventional anionic surfactant（aqueous soluble only）through core floods with Berea sandstone cores.Both simultaneous and alternating injections have been tested.The novel foam outperforms the conventional one with respect to faster foam propagation and higher desaturation rate.Furthermore,the novel injection strategy,CO2 continuous injection with dissolved CO2 -soluble surfactant,has been tested in the laboratory.Strong foam presented without delay.It is the first time the measured surfactant properties have been used to model foam transport on a field scale to extend our findings with the presence of gravity segregation.Different injection strategies have been tested under both constant rate and pressure constraints.It was showed that novel foam outperforms the conventional one in every scenario with much higher sweep efficiency and injectivity as well as more even pressure redistribution.Also,for this novel foam,it is not necessary that constant pressure injection is better,which has been concluded in previous literature for conventional foam.Furthermore,the novel injection strategy,CO2 continuous injection with dissolved CO2 -soluble surfactant,gave the best performance,which could lower the injection and water treatment cost.展开更多
Ground penetrating radar （GPR） is one of the promising technologies that can be used to detect landmines. Many factors may affect the ability of GPR to detect landmines. Among those factors are： 1） the type of lan...Ground penetrating radar （GPR） is one of the promising technologies that can be used to detect landmines. Many factors may affect the ability of GPR to detect landmines. Among those factors are： 1） the type of landmine material （metallic or plastic）, 2） conditions of the host soil （soil texture and soil moisture）, and 3） the radar frequency utilized. The impact of these factors on the ability of GPR to detect landmines is investigated by studying their effect on the dielectric permittivity contrast between the landmine and the host soil, as well as on the attenuation of the radar waves. The impact of each factor was theoretically reviewed and modeled using the Matlab and Mathcad software packages. Results of the computer modeling were correlated with GPR data acquired for metallic and plastic landmine types. It was found that the ability of GPR to detect landmines depends to a great extent on the landmine type, water content of the host soil, utilized radar frequency, and soil texture. The landmines are much easier to detect than plastic landmines for any soil conditions and any radar frequency. Increasing the soil＇s moisture content, regardless of soil texture, eases the detection of the plastic landmine and worsens the detection of the metallic mines. Increasing the percentage of clay in the soil causes the same effect as the moisture content. However, higher radar frequency delivers better results for landmine detection as long as the percentage of clay and the moisture content in the soil remains low. The results of this study are expected to help in selecting optimum radar antennae and data acquisition parameters depending on the landmine type and environmental conditions.展开更多
The basis of this study is to identify the versatility of N,N,N＇-trimethyl-N＇-tallow-1,3-diaminopropane（DTTM） surfactant in high saline environments. The surfactant was examined with sodium chloride, NaCl, to unde...The basis of this study is to identify the versatility of N,N,N＇-trimethyl-N＇-tallow-1,3-diaminopropane（DTTM） surfactant in high saline environments. The surfactant was examined with sodium chloride, NaCl, to understand how triggers such as salt, p H, temperature, and surfactant concentration influences the viscoelastic response of the surfactant solution. The DTTM surfactant and salt（NaCl） concentrations used in steady-state shear viscosity analysis range from 0.2 wt% to 2 wt%and 5 wt% to 25 wt%, respectively. Along with DTTM results, three similar chemical structures are investigated to understand how viscosity changes with alterations in tail and head group composition. It was found that DTTM surfactant has the capability of transitioning from a foam-bearing to viscoelastic state at low surfactant concentrations under moderate to high saline conditions. A longer tail length promotes viscoelasticity and shear-thinning behavior. Terminals consisting of hydroxides or ethoxylates have a lower viscosity than that of methyl terminals. A head group consisting of two nitrogen atoms has a higher viscosity than those containing one nitrogen atom. The rheological characterization of DTTM presented in this paper is part of a larger study in determining the capability of this surfactant to foam CO2 for improving mobility control in CO2 enhanced oil recovery in high saline oil formations.展开更多
Carbon Dioxide (CO2) storage and sequestration in unconventional shale resources has been attracting interest since last couple of years due to the very unique characteristics of such formations have made them a feasi...Carbon Dioxide (CO2) storage and sequestration in unconventional shale resources has been attracting interest since last couple of years due to the very unique characteristics of such formations have made them a feasible option for this object. Shale formations are found all around the world and the conventional assets are easily accessible, and also the huge move of operators toward developing unconventional reservoirs during past years leaves many of such formations ready for sequestering CO2. Today, the use of long horizontal wells that are drilled on a pad has the lowest amount of environmental footprint in which for storage and sequestration purpose also provides much more underground pore spaces available for CO2. In this paper we study the state of the art of the technology of CO2 storage and sequestration and provide different and fresh look for its complex phenomena from a mathematical modeling point of view. Moreover, we hope this study provides valuable insights into the use of depleted shale gas reservoirs for carbon sequestration, which as a result, a cleaner atmosphere will be achieved for the life of our next generations. Also, we present that the depleted shale gas reservoirs are very adequate for this purpose as they already have much of the infrastructure required to perform CO2 injection available in sites.展开更多
Steam-assisted gravity drainage(SAGD)is a mature technology for bitumen recovery from oil sands.However,it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen.The purpose o...Steam-assisted gravity drainage(SAGD)is a mature technology for bitumen recovery from oil sands.However,it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen.The purpose of this work is to develop ways to enhance SAGD performance through the use of organic base additives.The research is approached from three focus areas that supplement and guide each other:characterization tests,sand-pack floods,and computational simulation.A number of key mechanisms for enhancing oil recovery were identified,high-temperature additive characterization tests were developed,and promising alkalis were tested in porous media.Simulation was employed to history-match sandpack flood production data,in order to demonstrate the effect of an additive on the oil–water relative permeability.Based on these results,it was concluded that oxygenated organic bases had the most potential for improving bitumen recovery through reducing the oil–water interfacial tension(IFT)by increasing the pH of the system.These organic bases favorably modify the interfacial energies between the immiscible oil–water phases and enable them to flow easily through the porous media during production.Sand-pack flood tests have successfully demonstrated a 10%–15%improvement in bitumen recovery,over baseline,in the presence of IFT-reducing additives.Simulation results further showed that an IFT reduction had a positive impact on SAGD performance.This work demonstrates the potential of organic bases to improve not only SAGD,but other steam injection processes.Furthermore,a number of experimental methods were developed,tried,and tested during the course of this work.展开更多
Estimating formation permeability is crucial for production estimation,hydraulic fracturing design optimization and rate transient analysis.Laboratory experiments can be used to measure the permeability of rock sample...Estimating formation permeability is crucial for production estimation,hydraulic fracturing design optimization and rate transient analysis.Laboratory experiments can be used to measure the permeability of rock samples,but the results may not be representative at a field scale because of reservoir heterogeneity and pre-existing natural fracture systems.Diagnostic Fracture Injection Tests(DFIT)have now become standard practice to estimate formation pore pressure and formation permeability.However,in low permeability reservoirs,after-closure radial flow is often absent,which can cast significant uncertainties in interpreting DFIT data.Without knowing the fracture dimension prior,open fracture stiffness/compliance can't be determined,which is required for formation permeability estimation.Previous work has to assume a fracture radius or fracture height in order to estimate formation permeability,thus dent the confidence in the interpretation results.In the study,we present a new approach to determine fracture dimension,leak-off coefficient and formation permeability uniquely based on material balance and basic fracture mechanics,using data from shut-in to after-closure linear flow.Field examples are also presented to demonstrate the simplicity and effectiveness of this new approach.展开更多
文摘The ability of a novel nonionic CO2 -soluble surfactant to propagate foam in porous media was compared with that of a conventional anionic surfactant（aqueous soluble only）through core floods with Berea sandstone cores.Both simultaneous and alternating injections have been tested.The novel foam outperforms the conventional one with respect to faster foam propagation and higher desaturation rate.Furthermore,the novel injection strategy,CO2 continuous injection with dissolved CO2 -soluble surfactant,has been tested in the laboratory.Strong foam presented without delay.It is the first time the measured surfactant properties have been used to model foam transport on a field scale to extend our findings with the presence of gravity segregation.Different injection strategies have been tested under both constant rate and pressure constraints.It was showed that novel foam outperforms the conventional one in every scenario with much higher sweep efficiency and injectivity as well as more even pressure redistribution.Also,for this novel foam,it is not necessary that constant pressure injection is better,which has been concluded in previous literature for conventional foam.Furthermore,the novel injection strategy,CO2 continuous injection with dissolved CO2 -soluble surfactant,gave the best performance,which could lower the injection and water treatment cost.
文摘Ground penetrating radar （GPR） is one of the promising technologies that can be used to detect landmines. Many factors may affect the ability of GPR to detect landmines. Among those factors are： 1） the type of landmine material （metallic or plastic）, 2） conditions of the host soil （soil texture and soil moisture）, and 3） the radar frequency utilized. The impact of these factors on the ability of GPR to detect landmines is investigated by studying their effect on the dielectric permittivity contrast between the landmine and the host soil, as well as on the attenuation of the radar waves. The impact of each factor was theoretically reviewed and modeled using the Matlab and Mathcad software packages. Results of the computer modeling were correlated with GPR data acquired for metallic and plastic landmine types. It was found that the ability of GPR to detect landmines depends to a great extent on the landmine type, water content of the host soil, utilized radar frequency, and soil texture. The landmines are much easier to detect than plastic landmines for any soil conditions and any radar frequency. Increasing the soil＇s moisture content, regardless of soil texture, eases the detection of the plastic landmine and worsens the detection of the metallic mines. Increasing the percentage of clay in the soil causes the same effect as the moisture content. However, higher radar frequency delivers better results for landmine detection as long as the percentage of clay and the moisture content in the soil remains low. The results of this study are expected to help in selecting optimum radar antennae and data acquisition parameters depending on the landmine type and environmental conditions.
基金supported by the Abu Dhabi National Oil Company and the University of Texas at Austin
文摘The basis of this study is to identify the versatility of N,N,N＇-trimethyl-N＇-tallow-1,3-diaminopropane（DTTM） surfactant in high saline environments. The surfactant was examined with sodium chloride, NaCl, to understand how triggers such as salt, p H, temperature, and surfactant concentration influences the viscoelastic response of the surfactant solution. The DTTM surfactant and salt（NaCl） concentrations used in steady-state shear viscosity analysis range from 0.2 wt% to 2 wt%and 5 wt% to 25 wt%, respectively. Along with DTTM results, three similar chemical structures are investigated to understand how viscosity changes with alterations in tail and head group composition. It was found that DTTM surfactant has the capability of transitioning from a foam-bearing to viscoelastic state at low surfactant concentrations under moderate to high saline conditions. A longer tail length promotes viscoelasticity and shear-thinning behavior. Terminals consisting of hydroxides or ethoxylates have a lower viscosity than that of methyl terminals. A head group consisting of two nitrogen atoms has a higher viscosity than those containing one nitrogen atom. The rheological characterization of DTTM presented in this paper is part of a larger study in determining the capability of this surfactant to foam CO2 for improving mobility control in CO2 enhanced oil recovery in high saline oil formations.
文摘Carbon Dioxide (CO2) storage and sequestration in unconventional shale resources has been attracting interest since last couple of years due to the very unique characteristics of such formations have made them a feasible option for this object. Shale formations are found all around the world and the conventional assets are easily accessible, and also the huge move of operators toward developing unconventional reservoirs during past years leaves many of such formations ready for sequestering CO2. Today, the use of long horizontal wells that are drilled on a pad has the lowest amount of environmental footprint in which for storage and sequestration purpose also provides much more underground pore spaces available for CO2. In this paper we study the state of the art of the technology of CO2 storage and sequestration and provide different and fresh look for its complex phenomena from a mathematical modeling point of view. Moreover, we hope this study provides valuable insights into the use of depleted shale gas reservoirs for carbon sequestration, which as a result, a cleaner atmosphere will be achieved for the life of our next generations. Also, we present that the depleted shale gas reservoirs are very adequate for this purpose as they already have much of the infrastructure required to perform CO2 injection available in sites.
基金support of this research from The Dow Chemical Company
文摘Steam-assisted gravity drainage(SAGD)is a mature technology for bitumen recovery from oil sands.However,it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen.The purpose of this work is to develop ways to enhance SAGD performance through the use of organic base additives.The research is approached from three focus areas that supplement and guide each other:characterization tests,sand-pack floods,and computational simulation.A number of key mechanisms for enhancing oil recovery were identified,high-temperature additive characterization tests were developed,and promising alkalis were tested in porous media.Simulation was employed to history-match sandpack flood production data,in order to demonstrate the effect of an additive on the oil–water relative permeability.Based on these results,it was concluded that oxygenated organic bases had the most potential for improving bitumen recovery through reducing the oil–water interfacial tension(IFT)by increasing the pH of the system.These organic bases favorably modify the interfacial energies between the immiscible oil–water phases and enable them to flow easily through the porous media during production.Sand-pack flood tests have successfully demonstrated a 10%–15%improvement in bitumen recovery,over baseline,in the presence of IFT-reducing additives.Simulation results further showed that an IFT reduction had a positive impact on SAGD performance.This work demonstrates the potential of organic bases to improve not only SAGD,but other steam injection processes.Furthermore,a number of experimental methods were developed,tried,and tested during the course of this work.
文摘Estimating formation permeability is crucial for production estimation,hydraulic fracturing design optimization and rate transient analysis.Laboratory experiments can be used to measure the permeability of rock samples,but the results may not be representative at a field scale because of reservoir heterogeneity and pre-existing natural fracture systems.Diagnostic Fracture Injection Tests(DFIT)have now become standard practice to estimate formation pore pressure and formation permeability.However,in low permeability reservoirs,after-closure radial flow is often absent,which can cast significant uncertainties in interpreting DFIT data.Without knowing the fracture dimension prior,open fracture stiffness/compliance can't be determined,which is required for formation permeability estimation.Previous work has to assume a fracture radius or fracture height in order to estimate formation permeability,thus dent the confidence in the interpretation results.In the study,we present a new approach to determine fracture dimension,leak-off coefficient and formation permeability uniquely based on material balance and basic fracture mechanics,using data from shut-in to after-closure linear flow.Field examples are also presented to demonstrate the simplicity and effectiveness of this new approach.
