Asphaltenes are complex molecular entities, which together with resins, aromatic hydrocarbons and saturates forms the crude oil. Asphaltenes and resins are in the thermodynamic equilibrium at static reservoir conditio...Asphaltenes are complex molecular entities, which together with resins, aromatic hydrocarbons and saturates forms the crude oil. Asphaltenes and resins are in the thermodynamic equilibrium at static reservoir condition. However, asphaltene can precipitate due to changes in thermodynamic condition. Asphaltene deposition in production tubings has been an outstanding problem with wide economic impact on the oil industry. Meanwhile, the use of real-time tools to monitor depositions along the well is of great difficulty. In this work, the asphaltene precipitation region in a single phase flow wellbore is predicted for an oil well of the Iranian oil field. Then, asphaltene deposition thickness along the well is predicted for three time intervals. The simulation results indicated that asphaltene thickness exceeded more than 50% of tubing radius;therefore, a reduction in flow rate, an increase in pressure drop and tubing blockage are expected. Moreover, it is shown the deposits thickness along the wellbore has approximately a skew normal distribution shape, which could be the result of increases in velocity and excess pressure drop.展开更多
One of the most severe problems during production from heavy crude oil reservoirs is the formation of asphaltene precipitation and as a result deposition in the tubing,surface facilities and near wellbore region which...One of the most severe problems during production from heavy crude oil reservoirs is the formation of asphaltene precipitation and as a result deposition in the tubing,surface facilities and near wellbore region which causes oil production and permeability reduction in addition to rock wettability alteration in the reservoir.So one of the economical ways to prevent such incidents is using the chemicals which are called asphaltene inhibitor.In this study,the influence of three commercial inhibitors,namely;Cetyl Terimethyl Ammonium Bromide(CTAB),Sodium Dodecyl Sulfate(SDS),Triton X-100 and four non-commercial(Benzene,Benzoic Acid,Salicylic Acid,Naphthalene)inhibitors on two Iranian crude oils were investigated.This study extends previous works and contributes toward the better understanding of interactions between asphaltene and inhibitor.Effect of functional groups and structure of inhibitors on asphaltene precipitation were studied and it seems clear that the nature and polarity of asphaltene(structure and amount of impurities presented)has a significant impact on the selection of inhibitors.asphaltene dispersant tests and Core flood tests were designed for evaluation of inhibitors in static and dynamic conditions.The results revealed distinguished mechanisms for asphaltene solubilization/dispersion(such as hydrogen bonding,pep interaction and acid-base interaction)and influence of additional side group(OH)on inhibition power of inhibitor.During the experiments,it was found that increasing inhibitor concentration may lead to the self-assembly of inhibitor and declining of asphaltene stabilization.So,finding optimum concentration of inhibitor with high efficiency and available at a reasonable price is very important.The results suggest that 600 ppm of CTAB and 300 ppm of SDS were approximately optimum concentrations for the studied crude oils.One of the most important findings that differ from previous studies is the revelation of the mechanism behind the SDS/asphaltene behavior in various concentrations of inhibitor.Effect of chosen inhibitors on asphaltene precipitation and consequently deposition in porous media was studied,and then experimental data were modeled for evaluation of permeability impairment mechanisms.Permeability revived after inhibitor squeezing and cake formation mechanism played an important role in permeability reduction before and after treatment in porous media.The findings can also be applied to prediction of future behavior of reservoirs in oil field scale and evaluation of formation damage in the different period of production if needed any treatment process.展开更多
Different methods of enhanced oil recovery have been used to produce trapped oil.One of these methods is carbonated water injection in which CO2 contained water is injected in reservoirs in order to decrease free CO2 ...Different methods of enhanced oil recovery have been used to produce trapped oil.One of these methods is carbonated water injection in which CO2 contained water is injected in reservoirs in order to decrease free CO2 injection mobility,increase water viscosity and store/remove produced greenhouse CO2 gas safely.Another enhanced oil recovery method is smart water injection at which the ions in brine are modified in order to make controlled reactions with distributed ions on the surface of rock to cause more hydrocarbon recovery.Therefore,combination of these two methods may also have a great effect on enhancing oil recovery or may result in recovery factor less than each method used alone.In this paper hybrid smart carbonated water injection method is investigated to study its applicability in oil recovery using core flooding setup.The experimental core flooding setup was designed to perform different types of EOR methods for the sake of recovery comparison with the new hybrid method.The effect of both brine content and volume of CO2 is determining in hybrid EOR assessment.The main findings of this work show that the hybrid smart carbonated water results in the highest recovery factor in comparison to the most well-known EOR methods for carbonate cores.展开更多
The deposition of asphaltenes on the inner wall of oil wells and pipelines causes flow blockage and significant production loss in these conduits.The major underlying mechanism(s)for the deposition of asphaltene parti...The deposition of asphaltenes on the inner wall of oil wells and pipelines causes flow blockage and significant production loss in these conduits.The major underlying mechanism(s)for the deposition of asphaltene particles from the oil stream are still under investigation as an active research topic in the literature.In this work,a new deposition model considering both diffusional and inertial transport of asphaltene toward the tubing surface was developed.Model predictions were compared and verified with two sound experimental data available in the literature to evaluate the model's performance.A parametric study was done using the validated model in order to investigate the effect of the asphaltene particle size,flow velocity and oil viscosity on the magnitude of asphaltene deposition rate.Results of the study revealed that increasing the oil velocity causes more drag force on wall's inner surface;consequently,particles tend to transport away from the surface and the rate of asphaltene deposition is decreased.In addition,the developed model predicts that at low fluid velocity(~0.7 m/s),the less viscous oil is more prone to asphaltene deposition problem.展开更多
Transient rate decline curve analysis for constant pressure production is presented in this pa- per for a naturally fractured reservoir. This approach is based on exponential and constant bottom-hole pressure solution...Transient rate decline curve analysis for constant pressure production is presented in this pa- per for a naturally fractured reservoir. This approach is based on exponential and constant bottom-hole pressure solution. Based on this method, when In （flow rate） is plotted versus time, two straight lines are ob- tained which can be used for estimating different parameters of a naturally fractured reservoir. Parameters such as storage capacity ratio （co）, reservoir drainage area （A）, reservoir shape factor （CA）, fracture per- meability （ky）, interporosity flow parameter （,~） and the other parameters can be determined by this ap- proach. The equations are based on a model originally presented by Warren and Root and extended by Da Prat et al. and Mavor and Cinco-Ley. The proposed method has been developed to be used for naturally fractured reservoirs with different geometries. This method does not involve the use of any chart and by us- ing the pseudo steady state flow regime, the influence of wellbore storage on the value of the parameters ob- tained from this technique is negligible. In this technique, all the parameters can be obtained directly while in conventional approaches like type curve matching method, parameters such as co and g should be ob- tained by other methods like build-up test analysis and this is one of the most important advantages of this method that could save time during reservoir analyses. Different simulated and field examples were used for testing the proposed technique. Comparison between the obtained results by this approach and the results of type curve matching method shows a high performance of decline curves in well testing.展开更多
文摘Asphaltenes are complex molecular entities, which together with resins, aromatic hydrocarbons and saturates forms the crude oil. Asphaltenes and resins are in the thermodynamic equilibrium at static reservoir condition. However, asphaltene can precipitate due to changes in thermodynamic condition. Asphaltene deposition in production tubings has been an outstanding problem with wide economic impact on the oil industry. Meanwhile, the use of real-time tools to monitor depositions along the well is of great difficulty. In this work, the asphaltene precipitation region in a single phase flow wellbore is predicted for an oil well of the Iranian oil field. Then, asphaltene deposition thickness along the well is predicted for three time intervals. The simulation results indicated that asphaltene thickness exceeded more than 50% of tubing radius;therefore, a reduction in flow rate, an increase in pressure drop and tubing blockage are expected. Moreover, it is shown the deposits thickness along the wellbore has approximately a skew normal distribution shape, which could be the result of increases in velocity and excess pressure drop.
基金The authors would like to thank the Research Department of Ahwaz Petroleum University and National Iranian South Oil Company(NISOC)for supporting this study。
文摘One of the most severe problems during production from heavy crude oil reservoirs is the formation of asphaltene precipitation and as a result deposition in the tubing,surface facilities and near wellbore region which causes oil production and permeability reduction in addition to rock wettability alteration in the reservoir.So one of the economical ways to prevent such incidents is using the chemicals which are called asphaltene inhibitor.In this study,the influence of three commercial inhibitors,namely;Cetyl Terimethyl Ammonium Bromide(CTAB),Sodium Dodecyl Sulfate(SDS),Triton X-100 and four non-commercial(Benzene,Benzoic Acid,Salicylic Acid,Naphthalene)inhibitors on two Iranian crude oils were investigated.This study extends previous works and contributes toward the better understanding of interactions between asphaltene and inhibitor.Effect of functional groups and structure of inhibitors on asphaltene precipitation were studied and it seems clear that the nature and polarity of asphaltene(structure and amount of impurities presented)has a significant impact on the selection of inhibitors.asphaltene dispersant tests and Core flood tests were designed for evaluation of inhibitors in static and dynamic conditions.The results revealed distinguished mechanisms for asphaltene solubilization/dispersion(such as hydrogen bonding,pep interaction and acid-base interaction)and influence of additional side group(OH)on inhibition power of inhibitor.During the experiments,it was found that increasing inhibitor concentration may lead to the self-assembly of inhibitor and declining of asphaltene stabilization.So,finding optimum concentration of inhibitor with high efficiency and available at a reasonable price is very important.The results suggest that 600 ppm of CTAB and 300 ppm of SDS were approximately optimum concentrations for the studied crude oils.One of the most important findings that differ from previous studies is the revelation of the mechanism behind the SDS/asphaltene behavior in various concentrations of inhibitor.Effect of chosen inhibitors on asphaltene precipitation and consequently deposition in porous media was studied,and then experimental data were modeled for evaluation of permeability impairment mechanisms.Permeability revived after inhibitor squeezing and cake formation mechanism played an important role in permeability reduction before and after treatment in porous media.The findings can also be applied to prediction of future behavior of reservoirs in oil field scale and evaluation of formation damage in the different period of production if needed any treatment process.
文摘Different methods of enhanced oil recovery have been used to produce trapped oil.One of these methods is carbonated water injection in which CO2 contained water is injected in reservoirs in order to decrease free CO2 injection mobility,increase water viscosity and store/remove produced greenhouse CO2 gas safely.Another enhanced oil recovery method is smart water injection at which the ions in brine are modified in order to make controlled reactions with distributed ions on the surface of rock to cause more hydrocarbon recovery.Therefore,combination of these two methods may also have a great effect on enhancing oil recovery or may result in recovery factor less than each method used alone.In this paper hybrid smart carbonated water injection method is investigated to study its applicability in oil recovery using core flooding setup.The experimental core flooding setup was designed to perform different types of EOR methods for the sake of recovery comparison with the new hybrid method.The effect of both brine content and volume of CO2 is determining in hybrid EOR assessment.The main findings of this work show that the hybrid smart carbonated water results in the highest recovery factor in comparison to the most well-known EOR methods for carbonate cores.
文摘The deposition of asphaltenes on the inner wall of oil wells and pipelines causes flow blockage and significant production loss in these conduits.The major underlying mechanism(s)for the deposition of asphaltene particles from the oil stream are still under investigation as an active research topic in the literature.In this work,a new deposition model considering both diffusional and inertial transport of asphaltene toward the tubing surface was developed.Model predictions were compared and verified with two sound experimental data available in the literature to evaluate the model's performance.A parametric study was done using the validated model in order to investigate the effect of the asphaltene particle size,flow velocity and oil viscosity on the magnitude of asphaltene deposition rate.Results of the study revealed that increasing the oil velocity causes more drag force on wall's inner surface;consequently,particles tend to transport away from the surface and the rate of asphaltene deposition is decreased.In addition,the developed model predicts that at low fluid velocity(~0.7 m/s),the less viscous oil is more prone to asphaltene deposition problem.
文摘Transient rate decline curve analysis for constant pressure production is presented in this pa- per for a naturally fractured reservoir. This approach is based on exponential and constant bottom-hole pressure solution. Based on this method, when In （flow rate） is plotted versus time, two straight lines are ob- tained which can be used for estimating different parameters of a naturally fractured reservoir. Parameters such as storage capacity ratio （co）, reservoir drainage area （A）, reservoir shape factor （CA）, fracture per- meability （ky）, interporosity flow parameter （,~） and the other parameters can be determined by this ap- proach. The equations are based on a model originally presented by Warren and Root and extended by Da Prat et al. and Mavor and Cinco-Ley. The proposed method has been developed to be used for naturally fractured reservoirs with different geometries. This method does not involve the use of any chart and by us- ing the pseudo steady state flow regime, the influence of wellbore storage on the value of the parameters ob- tained from this technique is negligible. In this technique, all the parameters can be obtained directly while in conventional approaches like type curve matching method, parameters such as co and g should be ob- tained by other methods like build-up test analysis and this is one of the most important advantages of this method that could save time during reservoir analyses. Different simulated and field examples were used for testing the proposed technique. Comparison between the obtained results by this approach and the results of type curve matching method shows a high performance of decline curves in well testing.
