Combining low salinity water (LSW) with surfactants has an enormous potential for enhancing oil recovery processes. However, there is no consensus about the mechanisms involved, in addition to the fact that several st...Combining low salinity water (LSW) with surfactants has an enormous potential for enhancing oil recovery processes. However, there is no consensus about the mechanisms involved, in addition to the fact that several studies have been conducted in model systems, while experiments with rocks and reservoir fluids are scarce. This study presents a core-flooding experiment of LSW injection, with and without surfactant, using the core and heavy oil samples obtained from a sandstone reservoir in southeastern Mexico. The effluents and the crude oil obtained at each stage were analyzed. The study was complemented by tomographic analysis. The results revealed that LSW injection and hybrid process with surfactants obtained an increase of 11.4 percentage points in recovery factor. Various phenomena were caused by LSW flooding, such as changes in wettability and pH, ion exchange, mineral dissolution, detachment of fines and modification of the hydrocarbon profile. In the surfactant flooding, the reduction of interfacial tension and alteration of wettability were the main mechanisms involved. The findings of this work also showed that the conditions believed to be necessary for enhanced oil recovery with LSW, such as the presence of kaolinite or high acid number oil, are not relevant.展开更多
An experimental study was performed to investigate the impact of low salinity water on wettability alteration in carbonate core samples from southern Iranian reservoirs by spontaneous imbibition. In this paper, the ef...An experimental study was performed to investigate the impact of low salinity water on wettability alteration in carbonate core samples from southern Iranian reservoirs by spontaneous imbibition. In this paper, the effect of temperature, salinity,permeability and connate water were investigated by comparing the produced hydrocarbon curves. Contact angle measurements were taken to confirm the alteration of surface wettability of porous media. Oil recovery was enhanced by increasing the dilution ratio of sea water, and there existed an optimum dilution ratio at which the highest oil recovery was achieved. In addition, temperature had a very significant impact on oil recovery from carbonate rocks. Furthermore, oil recovery from a spontaneous imbibition process was directly proportional to the permeability of the core samples. The presence of connate water saturation inside the porous media facilitated oil production significantly. Also, the oil recovery from porous media was highly dependent on ion repulsion/attraction activity of the rock surface which directly impacts on the wettability conditions. Finally, the highest ion attraction percentage was measured for sodium while there was no significant change in pH for all experiments.展开更多
The low salinity water lenses(LSWLes) in the expansion area of the Changjiang diluted water(CDW) exist in a certain period of time in some years. The impact of realistic river runoff, ocean currents and weather co...The low salinity water lenses(LSWLes) in the expansion area of the Changjiang diluted water(CDW) exist in a certain period of time in some years. The impact of realistic river runoff, ocean currents and weather conditions need to be taken into account in the dynamical analysis of LSWL, which is in need of research. In this paper, the POM-σ-z model is used to set up the numerical model for the expansion of the CDW. Then LSWL in summer 1977 is simulated, and its dynamic mechanism driven by wind, tide, river runoff and the Taiwan Warm Current is also analyzed. The simulated results indicate that the isolated LSWL detaches itself from the CDW near the river mouth, and then moves towards the northeast region outside the Changjiang Estuary. Its maintaining period is from July 26 to August 11. Its formation and development is mainly driven by two factors. One is the strong southeasterly wind lasting for ten days. The other is the vertical tidal mixing during the transition from neap tide to spring tide.展开更多
A study comparative of rearing of the Pacific white shrimp (Litopenaeus vannamei) with the Nile tilapia (Oreochromis niloticus) in three earthen ponds (5,600 m^2) with the salinity ranged from 0.5-1.2 ppt and th...A study comparative of rearing of the Pacific white shrimp (Litopenaeus vannamei) with the Nile tilapia (Oreochromis niloticus) in three earthen ponds (5,600 m^2) with the salinity ranged from 0.5-1.2 ppt and three treatment ponds with salinity of 2-4 ppt by adding brine water into the ponds. Postlarvae 12 (PL12) of L. vannamei were stocked at density of 9 PL/m^2 and after one week the Nile tilapia fingerlings were stocked at density of I fish/m^2. Only pelleted feed were given to the fish during the 196-day rearing period. Shrimps were partially harvested by sieve net at day 80 and 120, and five days later PLI2 were stocked at the rate of 3 PL/m^2. After final harvesting at day 196, the production, body weight and survival from the treatment group were significantly higher (P 〈 0.05) than those of the control group. While the fish production body weight and survival rate from both groups were not significant differences (P 〉 0.051). The ionic concentration of six major ions (CI, SO42, Ca^2+, Na^+, Mg^2+ and K^+), salinity and hardness in the treatment ponds were significantly higher than those of the control ponds (P 〈 0.05). Moreover, the ionic profiles of the treatment ponds were similar to seawater at the salinity of 2 ppt while only 1 ppt in the control ponds. Results from the study indicated that in order to achieve good growth and survival rate of L. vannamei, brine water should be added into grow-out ponds prior to stocking and during the rearing: period to obtain and maintain the salinity not less than 2 ppt.展开更多
Chemical enhanced oil recovery(c-EOR)is a conventional and promising strategy to recover oil from reservoir techniques such as low salinity water flooding(LSWF),surfactant flooding,alkaline flooding,polymers flooding,...Chemical enhanced oil recovery(c-EOR)is a conventional and promising strategy to recover oil from reservoir techniques such as low salinity water flooding(LSWF),surfactant flooding,alkaline flooding,polymers flooding,and nanofluid flooding.The use of various types of chemical materials for c-EOR method has recently attracted the attention of the oil and gas industry.The primary objective of this review work is to explore the synergy of low salinity water/surfactant/nanoparticle flooding for effective c-EOR method and investigate the mechanism behind these methods.The advantages of combining these chemical materials for c-EOR methods is also reviewed.Challenges and limitations of this synergy and their economic feasibility for additional oil recovery and potential return on investment are reviewed.Nanoparticles have been successfully used in various applications in several industries and have also shown good application for EOR in terms of wettability alteration.LSWF contributes to wettability alteration,while surfactant contributes to wettability alteration and interfacial tension(IFT)reduction.However,fines migration caused by LSWF and nanoparticle agglomeration can cause formation damage,while excessive surfactant adsorption can lead to cost overrun on surfactant use.Understanding the characteristics of reservoir formation mineralogy and appropriate nanoparticle type,size,and concentration can be used to resolve this challenges.The synergy of LSWF and nanoparticles in alkaline medium can serve as sacrificial agent to reduce excessive surfactant loss.Therefore,the appropriate synergistic formulation of LSFW/surfactant/nanoparticle can improve additional oil recovery and support return on investment for c-EOR projects.展开更多
Although significant amount of H_(2)S(sour gas)rich natural gas is estimated globally,but not much attention has been given to the application of H_(2)S in the oil recovery process.Recent studies on the use of H_(2)S ...Although significant amount of H_(2)S(sour gas)rich natural gas is estimated globally,but not much attention has been given to the application of H_(2)S in the oil recovery process.Recent studies on the use of H_(2)S in oil recovery processes showed that H_(2)S has the potential of improving the oil recovery,and it can be even more effective than using CO_(2) in some processes.H_(2)S can equally dissolve in the water,react with the reservoir rock to change its surface charge,porosity,and permeability.However,previous in-vestigations on H_(2)S oil recovery attributed the improved oil recoveries to the higher miscibility of H_(2)S in the oil,and the reduction in the oil viscosity.Therefore,there is limited understanding on the H_(2)S-oil-brine-rock geochemical interactions,and how they impact the oil recovery process.This study aims to investigate the interactions between H_(2)S,oil,and carbonate formations,and to assess how the combi-nation of H_(2)S and low salinity water can impact the wettability and porosity of the reservoirs.A triple layer surface complexation model was used to understand the influence of key parameters(e.g.,pressure,brine salinity,and composition)on the H_(2)S-brine-oil-rock interactions.Moreover,the effects of mineral content of the carbonate rock on H_(2)S interactions were studied.Thereafter,the results of the H_(2)S-oil-brine-rock interactions were compared with a study where CO_(2) was used as the injected gas.Results of the study showed that the seawater and its diluted forms yielded identicalζ-potential values of about 3.31 mV at a pH of 3.24.This indicates that at very low pH condition,pH controls the ζ-potential of the oil-brine interface regardless of the brine's ionic strength.The study further demonstrated that the presence of other minerals in the carbonate rock greatly reduced the calcite dissolution.For instance,the calcite dissolution was reduced by 4.5%when anhydrite mineral was present in the carbonate rock.Findings from the simulation also indicated that CO_(2) produced negative ζ-potential values for the car-bonate rocks,and these values were reduced by 18.4%-20% when H_(2)S was used as the gas phase.This implies that the H_(2)S shifted the carbonate rockζ-potentials towards positive.The outcomes of this study can be applied when designing CO_(2) flooding and CO_(2) storage where the gas stream contains H_(2)S gas since H_(2)S greatly influences the dissolution of the carbonate mineral.展开更多
The capacitance-resistance model(CRM)has been widely implemented to model and optimise water-flooding and enhanced oil recovery(EOR)techniques.However,there is a gap in the application of CRM to analyse physical pheno...The capacitance-resistance model(CRM)has been widely implemented to model and optimise water-flooding and enhanced oil recovery(EOR)techniques.However,there is a gap in the application of CRM to analyse physical phenomena in porous media as well as the performance of EOR methods,such as low-salinity water(LSW)flooding.The main purposes of this study were to investigate how changes in time constant,as a CRM parameter,can represent physical phenomena in porous media such as wettability alteration.Moreover,to show CRM is a reliable tool to use for interpretation of LSW process as an EOR method.The results of different experimental/modelling studies in this research showed that in CRM model time constant increases when the wettability alters to a water wetness state,whereby the smallest time constant value is observed for the oil wet medium and the highest is observed for the water wet medium.The cases with a gradual alteration in wettability show an increasing trend with the dilution of the injection water.The core flooding data confirms the observed results of the simulation approach.The increment in time constant values indicates the resistance against displacing fluid,which is due to the wettability alteration of the porous medium,resulting in additional oil production.The observations made during this research illustrate that the time constant parameter can be a powerful tool for comparing different EOR techniques,since it is a good indication of the speed of impact of a particular injection fluid on production.展开更多
Investigating the enhanced oil recovery leads to optimal production,protection and reduction of lateral impacts.Low salinity water injection(LSWI)is one of the significantly improved oil recovery(IOR)techniques for ch...Investigating the enhanced oil recovery leads to optimal production,protection and reduction of lateral impacts.Low salinity water injection(LSWI)is one of the significantly improved oil recovery(IOR)techniques for changing the amount of wettability in the carbonate fractured reservoirs.The utilization of this methodology in terms of high efficiency in displacing light crude oils to the medium-gravity crude oils,water sources availability and its sustainability for pushing the oil which leads to appropriate economic occasions,are being compared with other IOR/EOR techniques.In this study,the best injection modelling pattern is based on the highest rate of recovery factor.Comparison of“high and low salinity water injection method”with“pure water injection method”is performed in an oil reservoir.Overall,analyzing the sensitivity on the high and low salinity according to the moderately low recovery factor of high and low salinity among the injection scenarios illustrates the low sensitivity of this parameter on a fractured carbonate reservoir.By reviewing different scenarios,it could be demonstrated that if the water injection could be applied to the reservoir from the preliminary times of production,the recovery factor rate would be increased.Thereby,higher appropriate efficiency and better supplement have resulted.Pure water injection has a high recovery factor than salty water injection.By the way,these two methods have little differences in calculating recovery methods.Besides,this parameter is significantly depended on wellhead equipment properties,safety factor and economic issues(water production).展开更多
The mechanism(s)of Low salinity water flooding(LSWF)has been extensively investigated for 15 e20 years,as a cost-effective and environmentally friendly technique for improved oil recovery.However,there is still no con...The mechanism(s)of Low salinity water flooding(LSWF)has been extensively investigated for 15 e20 years,as a cost-effective and environmentally friendly technique for improved oil recovery.However,there is still no consensus on the dominant mechanism(s)behind low salinity effect due to the complexity of interactions in the Crude oil/Brine/Rock(COBR)system.While wettability is most agreed mechanism of low salinity EOR effect.Nevertheless,the mechanism(s)behind the wettability change is debated between multi-component ion exchange(MIE)and double layer expansion(DLE)in sandstone reservoirs.This paper aims to investigate the effectiveness of MIE with a coupled geochemical-reservoir model using published experimental data reported by Nasralla and Nasr-El-Din[1].We created core-scale numerical models with parameters identical to those used in the experiments.We simulated the low salinity effect using a commercial reservoir simulator,CMG-GEM,by coupling three chemical reactions:(1)aqueous reaction,(2)multi-component ion exchange,and(3)mineral dissolution and precipitation.We modelled the adsorption of divalent cations on the surface of the clay minerals during low salinity water injection.Simulation results were compared with the experimental results.Simulation results show that the fractional adsorption of divalent cations(Ca^2+)increased almost 25%by injecting a 2000 ppm NaCl solution,compared to initial 10,000 ppm NaCl.Injecting a 2000 ppm of CaCl2 solution,however,significantly increased the adsorbed Ca^2+from 0.1 to 1,which implies the complete saturation of mineral surface with divalent cations.Moreover,injecting 50,000 ppm of CaCl2 solution also demonstrated the same effect as the 2000 ppm CaCl2 solution but with a faster rate.Upon combining the simulation and experimental results,we concluded that the multicomponent ion exchange is not the sole mechanism behind low salinity effect for two reasons.First,almost 10%additional oil recovery was observed from the experiments by injecting the 2000 ppm CaCl2 compared with 50,000 ppm CaCl2 solutions.Even though in both cases the surface is expected to be fully saturated with Ca^2+according to the geochemical modelling.Second,6%incremental oil recovery was achieved from the experiments by injecting 2000 ppm NaCl solution compared with that of 50,000 ppm NaCl.Although 25%incremental adsorption of divalent cations(Ca^2+)were presented during the flooding of the 2000 ppm NaCl solution.Therefore,it is worth noting that the electrical double layer expansion due to the ion exchange needs to be taken into account to pinpoint the mechanism(s)of low-salinity water effect.展开更多
One of the promising and emerging enhanced oil recovery techniques in both sandstones and carbonates is engineered water injection(EWI).However,few studies discussed the field-scale applications of this technique in h...One of the promising and emerging enhanced oil recovery techniques in both sandstones and carbonates is engineered water injection(EWI).However,few studies discussed the field-scale applications of this technique in heterogeneous carbonate formations.This paper is an extension of our previous work of the EWI technology at core-scale.This research numerically investigates heterogeneity effect on EWI technique in carbonates at field-scale using five-spot models.Three synthetic five-spot sector models were considered including homogeneous,heterogeneous with permeability channeling,and heterogeneous with gravity underride.The results showed that EWI improves both volumetric and displacement sweep efficiencies compared to conventional formation water injection(FWI)for all models investigated.Also,tracer method is recommended for better estimation of volumetric sweep efficiency as opposed to fractional flow method.Moreover,secondary EWI outperforms other techniques including secondary FW and tertiary EWI.In addition,the observed delay in tertiary EWI can be reduced by increasing well injection pressure and sulfate concentration in the engineered water.An optimum sulfate concentration of 25,000 ppm is recommended for achieving the highest oil recovery by EWI.This study gives more insight into understanding the performance of the EWI technique at field-scale.Recommendations for boosting the performance of this technique have been discussed,which assure more certainty and lower risk.展开更多
文摘Combining low salinity water (LSW) with surfactants has an enormous potential for enhancing oil recovery processes. However, there is no consensus about the mechanisms involved, in addition to the fact that several studies have been conducted in model systems, while experiments with rocks and reservoir fluids are scarce. This study presents a core-flooding experiment of LSW injection, with and without surfactant, using the core and heavy oil samples obtained from a sandstone reservoir in southeastern Mexico. The effluents and the crude oil obtained at each stage were analyzed. The study was complemented by tomographic analysis. The results revealed that LSW injection and hybrid process with surfactants obtained an increase of 11.4 percentage points in recovery factor. Various phenomena were caused by LSW flooding, such as changes in wettability and pH, ion exchange, mineral dissolution, detachment of fines and modification of the hydrocarbon profile. In the surfactant flooding, the reduction of interfacial tension and alteration of wettability were the main mechanisms involved. The findings of this work also showed that the conditions believed to be necessary for enhanced oil recovery with LSW, such as the presence of kaolinite or high acid number oil, are not relevant.
基金the National Iranian South Oil Company (NISOC) for generously funding the project
文摘An experimental study was performed to investigate the impact of low salinity water on wettability alteration in carbonate core samples from southern Iranian reservoirs by spontaneous imbibition. In this paper, the effect of temperature, salinity,permeability and connate water were investigated by comparing the produced hydrocarbon curves. Contact angle measurements were taken to confirm the alteration of surface wettability of porous media. Oil recovery was enhanced by increasing the dilution ratio of sea water, and there existed an optimum dilution ratio at which the highest oil recovery was achieved. In addition, temperature had a very significant impact on oil recovery from carbonate rocks. Furthermore, oil recovery from a spontaneous imbibition process was directly proportional to the permeability of the core samples. The presence of connate water saturation inside the porous media facilitated oil production significantly. Also, the oil recovery from porous media was highly dependent on ion repulsion/attraction activity of the rock surface which directly impacts on the wettability conditions. Finally, the highest ion attraction percentage was measured for sodium while there was no significant change in pH for all experiments.
基金supported by the National Natural Science Foundation of China(Grant Nos.40906044,41076048 and 41376012)the Fundamental Research Funds for the Central Universities(Grant No.2011B05714)the Doctoral Starting up Foundation of College of Meteorology and Oceanography of the PLA University of Science and Technology,China
文摘The low salinity water lenses(LSWLes) in the expansion area of the Changjiang diluted water(CDW) exist in a certain period of time in some years. The impact of realistic river runoff, ocean currents and weather conditions need to be taken into account in the dynamical analysis of LSWL, which is in need of research. In this paper, the POM-σ-z model is used to set up the numerical model for the expansion of the CDW. Then LSWL in summer 1977 is simulated, and its dynamic mechanism driven by wind, tide, river runoff and the Taiwan Warm Current is also analyzed. The simulated results indicate that the isolated LSWL detaches itself from the CDW near the river mouth, and then moves towards the northeast region outside the Changjiang Estuary. Its maintaining period is from July 26 to August 11. Its formation and development is mainly driven by two factors. One is the strong southeasterly wind lasting for ten days. The other is the vertical tidal mixing during the transition from neap tide to spring tide.
文摘A study comparative of rearing of the Pacific white shrimp (Litopenaeus vannamei) with the Nile tilapia (Oreochromis niloticus) in three earthen ponds (5,600 m^2) with the salinity ranged from 0.5-1.2 ppt and three treatment ponds with salinity of 2-4 ppt by adding brine water into the ponds. Postlarvae 12 (PL12) of L. vannamei were stocked at density of 9 PL/m^2 and after one week the Nile tilapia fingerlings were stocked at density of I fish/m^2. Only pelleted feed were given to the fish during the 196-day rearing period. Shrimps were partially harvested by sieve net at day 80 and 120, and five days later PLI2 were stocked at the rate of 3 PL/m^2. After final harvesting at day 196, the production, body weight and survival from the treatment group were significantly higher (P 〈 0.05) than those of the control group. While the fish production body weight and survival rate from both groups were not significant differences (P 〉 0.051). The ionic concentration of six major ions (CI, SO42, Ca^2+, Na^+, Mg^2+ and K^+), salinity and hardness in the treatment ponds were significantly higher than those of the control ponds (P 〈 0.05). Moreover, the ionic profiles of the treatment ponds were similar to seawater at the salinity of 2 ppt while only 1 ppt in the control ponds. Results from the study indicated that in order to achieve good growth and survival rate of L. vannamei, brine water should be added into grow-out ponds prior to stocking and during the rearing: period to obtain and maintain the salinity not less than 2 ppt.
基金supported by the Ministry of Higher Education,Malaysia under the Fundamental Research Grant Scheme:FRGS/1/2020/TK0/CURTIN/03/10.
文摘Chemical enhanced oil recovery(c-EOR)is a conventional and promising strategy to recover oil from reservoir techniques such as low salinity water flooding(LSWF),surfactant flooding,alkaline flooding,polymers flooding,and nanofluid flooding.The use of various types of chemical materials for c-EOR method has recently attracted the attention of the oil and gas industry.The primary objective of this review work is to explore the synergy of low salinity water/surfactant/nanoparticle flooding for effective c-EOR method and investigate the mechanism behind these methods.The advantages of combining these chemical materials for c-EOR methods is also reviewed.Challenges and limitations of this synergy and their economic feasibility for additional oil recovery and potential return on investment are reviewed.Nanoparticles have been successfully used in various applications in several industries and have also shown good application for EOR in terms of wettability alteration.LSWF contributes to wettability alteration,while surfactant contributes to wettability alteration and interfacial tension(IFT)reduction.However,fines migration caused by LSWF and nanoparticle agglomeration can cause formation damage,while excessive surfactant adsorption can lead to cost overrun on surfactant use.Understanding the characteristics of reservoir formation mineralogy and appropriate nanoparticle type,size,and concentration can be used to resolve this challenges.The synergy of LSWF and nanoparticles in alkaline medium can serve as sacrificial agent to reduce excessive surfactant loss.Therefore,the appropriate synergistic formulation of LSFW/surfactant/nanoparticle can improve additional oil recovery and support return on investment for c-EOR projects.
文摘Although significant amount of H_(2)S(sour gas)rich natural gas is estimated globally,but not much attention has been given to the application of H_(2)S in the oil recovery process.Recent studies on the use of H_(2)S in oil recovery processes showed that H_(2)S has the potential of improving the oil recovery,and it can be even more effective than using CO_(2) in some processes.H_(2)S can equally dissolve in the water,react with the reservoir rock to change its surface charge,porosity,and permeability.However,previous in-vestigations on H_(2)S oil recovery attributed the improved oil recoveries to the higher miscibility of H_(2)S in the oil,and the reduction in the oil viscosity.Therefore,there is limited understanding on the H_(2)S-oil-brine-rock geochemical interactions,and how they impact the oil recovery process.This study aims to investigate the interactions between H_(2)S,oil,and carbonate formations,and to assess how the combi-nation of H_(2)S and low salinity water can impact the wettability and porosity of the reservoirs.A triple layer surface complexation model was used to understand the influence of key parameters(e.g.,pressure,brine salinity,and composition)on the H_(2)S-brine-oil-rock interactions.Moreover,the effects of mineral content of the carbonate rock on H_(2)S interactions were studied.Thereafter,the results of the H_(2)S-oil-brine-rock interactions were compared with a study where CO_(2) was used as the injected gas.Results of the study showed that the seawater and its diluted forms yielded identicalζ-potential values of about 3.31 mV at a pH of 3.24.This indicates that at very low pH condition,pH controls the ζ-potential of the oil-brine interface regardless of the brine's ionic strength.The study further demonstrated that the presence of other minerals in the carbonate rock greatly reduced the calcite dissolution.For instance,the calcite dissolution was reduced by 4.5%when anhydrite mineral was present in the carbonate rock.Findings from the simulation also indicated that CO_(2) produced negative ζ-potential values for the car-bonate rocks,and these values were reduced by 18.4%-20% when H_(2)S was used as the gas phase.This implies that the H_(2)S shifted the carbonate rockζ-potentials towards positive.The outcomes of this study can be applied when designing CO_(2) flooding and CO_(2) storage where the gas stream contains H_(2)S gas since H_(2)S greatly influences the dissolution of the carbonate mineral.
基金would like to thank Nazarbayev University for supporting this research through the NU Faculty Development Competitive Research Grants program(Award number:110119FD4541).
文摘The capacitance-resistance model(CRM)has been widely implemented to model and optimise water-flooding and enhanced oil recovery(EOR)techniques.However,there is a gap in the application of CRM to analyse physical phenomena in porous media as well as the performance of EOR methods,such as low-salinity water(LSW)flooding.The main purposes of this study were to investigate how changes in time constant,as a CRM parameter,can represent physical phenomena in porous media such as wettability alteration.Moreover,to show CRM is a reliable tool to use for interpretation of LSW process as an EOR method.The results of different experimental/modelling studies in this research showed that in CRM model time constant increases when the wettability alters to a water wetness state,whereby the smallest time constant value is observed for the oil wet medium and the highest is observed for the water wet medium.The cases with a gradual alteration in wettability show an increasing trend with the dilution of the injection water.The core flooding data confirms the observed results of the simulation approach.The increment in time constant values indicates the resistance against displacing fluid,which is due to the wettability alteration of the porous medium,resulting in additional oil production.The observations made during this research illustrate that the time constant parameter can be a powerful tool for comparing different EOR techniques,since it is a good indication of the speed of impact of a particular injection fluid on production.
文摘Investigating the enhanced oil recovery leads to optimal production,protection and reduction of lateral impacts.Low salinity water injection(LSWI)is one of the significantly improved oil recovery(IOR)techniques for changing the amount of wettability in the carbonate fractured reservoirs.The utilization of this methodology in terms of high efficiency in displacing light crude oils to the medium-gravity crude oils,water sources availability and its sustainability for pushing the oil which leads to appropriate economic occasions,are being compared with other IOR/EOR techniques.In this study,the best injection modelling pattern is based on the highest rate of recovery factor.Comparison of“high and low salinity water injection method”with“pure water injection method”is performed in an oil reservoir.Overall,analyzing the sensitivity on the high and low salinity according to the moderately low recovery factor of high and low salinity among the injection scenarios illustrates the low sensitivity of this parameter on a fractured carbonate reservoir.By reviewing different scenarios,it could be demonstrated that if the water injection could be applied to the reservoir from the preliminary times of production,the recovery factor rate would be increased.Thereby,higher appropriate efficiency and better supplement have resulted.Pure water injection has a high recovery factor than salty water injection.By the way,these two methods have little differences in calculating recovery methods.Besides,this parameter is significantly depended on wellhead equipment properties,safety factor and economic issues(water production).
文摘The mechanism(s)of Low salinity water flooding(LSWF)has been extensively investigated for 15 e20 years,as a cost-effective and environmentally friendly technique for improved oil recovery.However,there is still no consensus on the dominant mechanism(s)behind low salinity effect due to the complexity of interactions in the Crude oil/Brine/Rock(COBR)system.While wettability is most agreed mechanism of low salinity EOR effect.Nevertheless,the mechanism(s)behind the wettability change is debated between multi-component ion exchange(MIE)and double layer expansion(DLE)in sandstone reservoirs.This paper aims to investigate the effectiveness of MIE with a coupled geochemical-reservoir model using published experimental data reported by Nasralla and Nasr-El-Din[1].We created core-scale numerical models with parameters identical to those used in the experiments.We simulated the low salinity effect using a commercial reservoir simulator,CMG-GEM,by coupling three chemical reactions:(1)aqueous reaction,(2)multi-component ion exchange,and(3)mineral dissolution and precipitation.We modelled the adsorption of divalent cations on the surface of the clay minerals during low salinity water injection.Simulation results were compared with the experimental results.Simulation results show that the fractional adsorption of divalent cations(Ca^2+)increased almost 25%by injecting a 2000 ppm NaCl solution,compared to initial 10,000 ppm NaCl.Injecting a 2000 ppm of CaCl2 solution,however,significantly increased the adsorbed Ca^2+from 0.1 to 1,which implies the complete saturation of mineral surface with divalent cations.Moreover,injecting 50,000 ppm of CaCl2 solution also demonstrated the same effect as the 2000 ppm CaCl2 solution but with a faster rate.Upon combining the simulation and experimental results,we concluded that the multicomponent ion exchange is not the sole mechanism behind low salinity effect for two reasons.First,almost 10%additional oil recovery was observed from the experiments by injecting the 2000 ppm CaCl2 compared with 50,000 ppm CaCl2 solutions.Even though in both cases the surface is expected to be fully saturated with Ca^2+according to the geochemical modelling.Second,6%incremental oil recovery was achieved from the experiments by injecting 2000 ppm NaCl solution compared with that of 50,000 ppm NaCl.Although 25%incremental adsorption of divalent cations(Ca^2+)were presented during the flooding of the 2000 ppm NaCl solution.Therefore,it is worth noting that the electrical double layer expansion due to the ion exchange needs to be taken into account to pinpoint the mechanism(s)of low-salinity water effect.
基金partially supported by Khalifa University under Award No.[FSU-2018-26].
文摘One of the promising and emerging enhanced oil recovery techniques in both sandstones and carbonates is engineered water injection(EWI).However,few studies discussed the field-scale applications of this technique in heterogeneous carbonate formations.This paper is an extension of our previous work of the EWI technology at core-scale.This research numerically investigates heterogeneity effect on EWI technique in carbonates at field-scale using five-spot models.Three synthetic five-spot sector models were considered including homogeneous,heterogeneous with permeability channeling,and heterogeneous with gravity underride.The results showed that EWI improves both volumetric and displacement sweep efficiencies compared to conventional formation water injection(FWI)for all models investigated.Also,tracer method is recommended for better estimation of volumetric sweep efficiency as opposed to fractional flow method.Moreover,secondary EWI outperforms other techniques including secondary FW and tertiary EWI.In addition,the observed delay in tertiary EWI can be reduced by increasing well injection pressure and sulfate concentration in the engineered water.An optimum sulfate concentration of 25,000 ppm is recommended for achieving the highest oil recovery by EWI.This study gives more insight into understanding the performance of the EWI technique at field-scale.Recommendations for boosting the performance of this technique have been discussed,which assure more certainty and lower risk.