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Mingzhe Dong - One of the best experts on this subject based on the ideXlab platform.

  • effect of wettability alteration on enhanced heavy oil recovery by Alkaline Flooding
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016
    Co-Authors: Houjian Gong, Mingzhe Dong, Weirong Liu
    Abstract:

    Abstract Alkaline Flooding is a promising enhanced heavy oil recovery method. In this paper, this enhanced heavy oil recovery method is investigated in terms of its tertiary oil recovery potential and its effects on wettability alteration of the porous medium. Core flood tests show that the tertiary oil recovery can be greater than 10% of the initial oil in place (IOIP) by NaOH-only Flooding or with NaOH and Na 2 CO 3 mixed Flooding systems. Micromodel experiments show that the wettability of the pore walls in the micromodel had been changed from water-wet to oil-wet, which can block water channeling and thereby improve the sweep efficiency. In order to prove the effect of wettability alteration on the enhanced heavy oil recovery, the contact angles of the heavy oil in Alkaline solution on a quartz substrate have been measured. The results show that the contact angle can change from 24°, without alkali, to about 160°, under the action of NaOH or Na 2 CO 3 . The wettability alteration from water-wet to oil-wet can make the heavy oil adsorb at the rock surface and block the water channel. Therefore, the wettability alteration is one of the important mechanisms for enhanced heavy oil recovery by Alkaline Flooding.

  • displacement mechanisms of enhanced heavy oil recovery by Alkaline Flooding in a micromodel
    Particuology, 2012
    Co-Authors: Mingzhe Dong, Qiang Liu
    Abstract:

    Abstract Enhanced oil recovery (EOR) by Alkaline Flooding for conventional oils has been extensively studied. For heavy oils, investigations are very limited due to the unfavorable mobility ratio between the water and oil phases. In this study, the displacement mechanisms of Alkaline Flooding for heavy oil EOR are investigated by conducting flood tests in a micromodel. Two different displacement mechanisms are observed for enhancing heavy oil recovery. One is in situ water-in-oil (W/O) emulsion formation and partial wettability alteration. The W/O emulsion formed during the injection of Alkaline solution plugs high permeability water channels, and pore walls are altered to become partially oil-wetted, leading to an improvement in sweep efficiency and high tertiary oil recovery. The other mechanism is the formation of an oil-in-water (O/W) emulsion. Heavy oil is dispersed into the water phase by injecting an Alkaline solution containing a very dilute surfactant. The oil is then entrained in the water phase and flows out of the model with the water phase.

  • experimental and numerical study of improving heavy oil recovery by Alkaline Flooding in sandpacks
    Journal of Canadian Petroleum Technology, 2010
    Co-Authors: J Wang, Mingzhe Dong, Mohamed Arhuoma
    Abstract:

    Chemical Flooding has great potential for enhancing heavy oil recovery, especially for reservoirs where thermal methods are not feasible. It has been shown that the formation of emulsions during chemical Flooding can effectively improve sweep efficiency and, consequently, increase heavy oil recovery. The mechanism of flow of oil-in-water (O/W) emulsion in porous media has been extensively studied and simulated using the filtration theory. Few studies have been done for the modelling of water-in-oil (W/O) emulsion flow in heavy oil reservoirs. This study experimentally investigated the effective viscosity of W/O emulsion in porous media. Alkaline Flooding tests were performed in channelled sandpacks to demonstrate the effectiveness of sweep efficiency improvement by the in-situ produced W/O emulsions. High tertiary oil recoveries were obtained for all these tests. The Alkaline Flooding process was simulated by including the observed flow behaviour of extra resistance to water phase flow caused by the formation of W/O emulsions, as well as the adsorption of chemicals, interfacial tension reduction, and in-situ generation of W/O emulsions. These laboratory results and the developed simulation technique are proposed as an improvement to the simulation and design of the field-scale projects of chemical Flooding for heavy oil recovery.

  • numerical simulation of displacement mechanisms for enhancing heavy oil recovery during Alkaline Flooding
    Energy & Fuels, 2009
    Co-Authors: Mohamed Arhuoma, Mingzhe Dong, Daoyong Yang, Raphael Idem
    Abstract:

    In this paper, a simulation technique has been developed and successfully applied to numerically simulate the experimentally determined displacement mechanisms governing Alkaline Flooding for enhancing oil recovery in heavy oil reservoirs. The measured pressure drop and oil recovery during the Alkaline Flooding processes have been found to increase as the Alkaline concentration increases. The increase in pressure drop is mainly due to in situ formation of water-in-oil (W/O) emulsions, and oil recovery is thus improved because of the blockage of the high-permeability zones. The interfacial tension between heavy oil and Alkaline solutions, viscosity of the in situ generated W/O emulsion, and relative permeabilities during waterFlooding and Alkaline Flooding processes have been experimentally determined. An excellent agreement between the measured and simulated pressure drop and cumulative oil production are obtained by taking both the measured viscosity of W/O emulsions and the relative permeability into ac...

  • wettability alteration by magnesium ion binding in heavy oil brine chemical sand systems analysis of electrostatic forces
    Journal of Petroleum Science and Engineering, 2007
    Co-Authors: Qiang Liu, Mingzhe Dong, Koorosh Asghari
    Abstract:

    Abstract In laboratory coreflood tests for enhanced heavy oil recovery by Alkaline Flooding, it was found that oil recovery was greatly affected by wettability alteration of sand. In this study, a heavy oil of 14°API was used to study the effect of the composition of the water phase on wettability alteration in the heavy oil/water/sand system. In micro-slide and micro-model tests, wettability change was observed. The presence of either Na 2 CO 3 or Mg 2+ alone in the water phase could not induce wettability alteration. When the water phase contained both Na 2 CO 3 and Mg 2+ , the water-wet sand became preferentially oil-wet by magnesium ion binding. The reduction in zeta (ζ)-potential value due to the addition of Mg 2+ into the heavy oil/Na 2 CO 3 solution/sand system confirmed the combination of Mg 2+ and ionized organic acids at the oil/water interface. In addition, the ζ-potential value of sand in the water phase suggested that Mg 2+ also adsorbed on sand surfaces, weakening the electrostatic forces. The reduction of repulsive electrostatic forces between oil drops and sand surfaces contributed to the wettability change of the sand from water-wet to more oil-wet.

Haihua Pei - One of the best experts on this subject based on the ideXlab platform.

  • effect of the addition of low molecular weight alcohols on heavy oil recovery during Alkaline Flooding
    Industrial & Engineering Chemistry Research, 2014
    Co-Authors: Haihua Pei, Guicai Zhang, Lei Zhang
    Abstract:

    This study presents an experimental study, including interfacial tension (IFT) measurements, sandpack flood tests, and microscopic studies, for investigating the effect of the addition of low molecular weight alcohols on heavy oil recovery during Alkaline Flooding. According to the IFT results, the addition of low molecular weight alcohols can be detrimental to IFT reduction for the Alkaline/heavy oil system, due to the partitioning of the alcohol molecules at the oil–water interface reducing the interfacial space available for surfactant molecules. However, sandpack floods conducted with the addition of the low molecular weight alcohols show a marked improvement in oil recovery over the Alkaline-only Flooding. The incremental oil recovery increases with the alcohol chain length from methanol to n-pentanol, but for the less water-soluble isoamyl alcohol and n-hexanol, the incremental oil recovery starts to decrease. The microscopic studies indicate that the alcohol additives can accelerate the reaction ra...

  • investigation into the mechanisms of heavy oil recovery by novel Alkaline Flooding
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013
    Co-Authors: Mingguang Tang, Haihua Pei, Guicai Zhang, Ping Jiang, Qinghua Liu, Lifeng Chen
    Abstract:

    Abstract To investigate the mechanism of alkali Flooding for heavy oil recovery, sodium metaborate, which has strong chelating capacity for calcium and magnesium ions, is selected for laboratory research to evaluate its displacement efficiency using sandpacks. The results show that the dynamic interfacial tension between the alkali solution and Xia-8 crude oil is high, and the sandpack tests give evidence of good displacement efficiency, showing that 1.0% NaBO2 can enhance oil recovery by 27.1%. During the displacement process, a large differential pressure response occurs when the alkali concentration is high, and the incremental oil recovery increases with the Alkaline concentration. When 0.1% SBET-12 was added to the alkali solution, the interfacial tension was significantly reduced, but the displacement efficiency showed no obvious improvement. 0.1% HPAM was added to the solution to adjust the mobility ratio. However, ternary Flooding (NaBO2 + 0.1% SBET-12 + 0.1% HPAM) and binary Flooding (NaBO2 + 0.1% HPAM) have the same effect on oil recovery, which shows that the SBET-12 has little effect in improving the recovery of Xia-8 crude oil. The glass etching model test, which is used to further determine the enhanced heavy oil recovery mechanisms of sodium metaborate, shows that the microscopic mechanism involves Alkaline solution penetration into the crude oil and the formation of water droplets inside the oil phase, which may act to block the water channel and inhibit the viscous fingering, leading to an improvement of the sweep efficiency.

  • potential of Alkaline Flooding to enhance heavy oil recovery through water in oil emulsification
    Fuel, 2013
    Co-Authors: Haihua Pei, Guicai Zhang, Luchao Jin
    Abstract:

    Abstract Alkaline Flooding has great potential for enhancing the recovery of heavy oil, especially for reservoirs in which thermal methods are not suitable. In this study, Alkaline Flooding tests were performed in micromodels and sandpacks to investigate the microscopic displacement mechanisms for enhancing heavy oil recovery and the effect of the injection parameters on displacement efficiency. The micromodel tests indicate that the penetration of the Alkaline solution into the crude oil and the subsequent formation of a water-in-oil (W/O) emulsion reduce the mobility of the water phase and divert the injected water into the unswept region, thereby improving the sweep efficiency. The sandpack flood results show that the tertiary oil recovery can reach about 20% of the initial oil in place (IOIP) using 1.0% NaOH, and the tertiary oil recovery has been found to increase as the Alkaline concentration increases. However, there is an optimum slug size and injection rate at which the highest tertiary oil recovery can be obtained during the Alkaline Flooding process. Continuous Alkaline injection can provide a higher tertiary oil recovery compared with a cyclic Alkaline injection pattern. These results show that the Alkaline Flooding, if properly designed and controlled, can lead to enhanced heavy oil recovery through the water-in-oil emulsification.

  • study on the variation of dynamic interfacial tension in the process of Alkaline Flooding for heavy oil
    Fuel, 2013
    Co-Authors: Haihua Pei, Guicai Zhang, Luchao Jin, Lei Ding
    Abstract:

    Abstract Experimental investigations have been conducted to elucidate the variation of the dynamic interfacial tension (DIFT) in the process of Alkaline Flooding for heavy oil. The Binnan heavy oil with high TAN (Total Acid Number) and the Zhuangxi heavy oil with low TAN were pre-equilibrated by long-term contacting with NaOH and Na 2 CO 3 solutions. The results show that the heavy oil pre-equilibrated by NaOH solutions almost loses the interfacial activity, and the IFT increases a lot. Although there is still interfacial activity in the heavy oil which is pre-equilibrated by Na 2 CO 3 solutions, and the dynamic interfacial tension minimum (DIFT min ) changes a little, yet the dynamic interfacial tension equilibrium value (DIFT eq ) increases a lot. The effect of interfacial reaction on the interfacial property of oil with low TAN is more severe than that with high TAN. When the Alkaline concentration is larger than a certain value, the IFT between the fresh oil with high TAN and the equilibrated Alkaline solutions can decrease to ultralow after interfacial reaction, and the Na 2 CO 3 system is superior to the NaOH system. However, the IFT between the fresh oil with low TAN and the equilibrated Alkaline solutions increases after interfacial reaction. The above results can be used as guidance in the formulation design and mechanisms studies of Alkaline Flooding for improved heavy oil recovery.

  • study of the factors influencing Alkaline Flooding in heavy oil reservoirs
    Energy & Fuels, 2012
    Co-Authors: Anzhou Feng, Guicai Zhang, Ping Jiang, Haihua Pei
    Abstract:

    The effects of the oil acid number, Alkaline concentration and type, brine salinity, and test temperature on Alkaline Flooding for heavy oil are investigated in this study. The results indicate that the tertiary oil recovery is positively affected by the oil acid number, which is a prominent factor in Alkaline Flooding. Another important factor is Alkaline fluid. The best displacement efficiency can be achieved only when the Alkaline concentration reaches a certain value. However, honeycomb oil blocks with a poor mobility may form when the Alkaline concentration is too high. In comparison to Na2CO3, NaOH performs better in Alkaline Flooding for Zhuangxi 106 heavy oil. In addition, the performance of Alkaline Flooding is also affected by the brine salinity and test temperature. There is an optimum brine salinity for Alkaline Flooding, and the relatively low temperature is beneficial to Alkaline Flooding. When the temperature increases to a certain value, the displacement efficiency declines intensively. Al...

Guicai Zhang - One of the best experts on this subject based on the ideXlab platform.

  • effect of the addition of low molecular weight alcohols on heavy oil recovery during Alkaline Flooding
    Industrial & Engineering Chemistry Research, 2014
    Co-Authors: Haihua Pei, Guicai Zhang, Lei Zhang
    Abstract:

    This study presents an experimental study, including interfacial tension (IFT) measurements, sandpack flood tests, and microscopic studies, for investigating the effect of the addition of low molecular weight alcohols on heavy oil recovery during Alkaline Flooding. According to the IFT results, the addition of low molecular weight alcohols can be detrimental to IFT reduction for the Alkaline/heavy oil system, due to the partitioning of the alcohol molecules at the oil–water interface reducing the interfacial space available for surfactant molecules. However, sandpack floods conducted with the addition of the low molecular weight alcohols show a marked improvement in oil recovery over the Alkaline-only Flooding. The incremental oil recovery increases with the alcohol chain length from methanol to n-pentanol, but for the less water-soluble isoamyl alcohol and n-hexanol, the incremental oil recovery starts to decrease. The microscopic studies indicate that the alcohol additives can accelerate the reaction ra...

  • influence of oil viscosity on Alkaline Flooding for enhanced heavy oil recovery
    Journal of Chemistry, 2013
    Co-Authors: Guicai Zhang, Anzhou Feng
    Abstract:

    Oil viscosity was studied as an important factor for Alkaline Flooding based on the mechanism of “water drops” flow. Alkaline Flooding for two oil samples with different viscosities but similar acid numbers was compared. Besides, series Flooding tests for the same oil sample were conducted at different temperatures and permeabilities. The results of Flooding tests indicated that a high tertiary oil recovery could be achieved only in the low-permeability (approximately 500 mD) sandpacks for the low-viscosity heavy oil (Zhuangxi, 390 mPa·s); however, the high-viscosity heavy oil (Chenzhuang, 3450 mPa·s) performed well in both the low- and medium-permeability (approximately 1000 mD) sandpacks. In addition, the results of Flooding tests for the same oil at different temperatures also indicated that the oil viscosity put a similar effect on Alkaline Flooding. Therefore, oil with a high-viscosity is favorable for Alkaline Flooding. The microscopic Flooding test indicated that the water drops produced during Alkaline Flooding for oils with different viscosities differed significantly in their sizes, which might influence the flow behaviors and therefore the sweep efficiencies of Alkaline fluids. This study provides an evidence for the feasibility of the development of high-viscosity heavy oil using Alkaline Flooding.

  • investigation into the mechanisms of heavy oil recovery by novel Alkaline Flooding
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013
    Co-Authors: Mingguang Tang, Haihua Pei, Guicai Zhang, Ping Jiang, Qinghua Liu, Lifeng Chen
    Abstract:

    Abstract To investigate the mechanism of alkali Flooding for heavy oil recovery, sodium metaborate, which has strong chelating capacity for calcium and magnesium ions, is selected for laboratory research to evaluate its displacement efficiency using sandpacks. The results show that the dynamic interfacial tension between the alkali solution and Xia-8 crude oil is high, and the sandpack tests give evidence of good displacement efficiency, showing that 1.0% NaBO2 can enhance oil recovery by 27.1%. During the displacement process, a large differential pressure response occurs when the alkali concentration is high, and the incremental oil recovery increases with the Alkaline concentration. When 0.1% SBET-12 was added to the alkali solution, the interfacial tension was significantly reduced, but the displacement efficiency showed no obvious improvement. 0.1% HPAM was added to the solution to adjust the mobility ratio. However, ternary Flooding (NaBO2 + 0.1% SBET-12 + 0.1% HPAM) and binary Flooding (NaBO2 + 0.1% HPAM) have the same effect on oil recovery, which shows that the SBET-12 has little effect in improving the recovery of Xia-8 crude oil. The glass etching model test, which is used to further determine the enhanced heavy oil recovery mechanisms of sodium metaborate, shows that the microscopic mechanism involves Alkaline solution penetration into the crude oil and the formation of water droplets inside the oil phase, which may act to block the water channel and inhibit the viscous fingering, leading to an improvement of the sweep efficiency.

  • potential of Alkaline Flooding to enhance heavy oil recovery through water in oil emulsification
    Fuel, 2013
    Co-Authors: Haihua Pei, Guicai Zhang, Luchao Jin
    Abstract:

    Abstract Alkaline Flooding has great potential for enhancing the recovery of heavy oil, especially for reservoirs in which thermal methods are not suitable. In this study, Alkaline Flooding tests were performed in micromodels and sandpacks to investigate the microscopic displacement mechanisms for enhancing heavy oil recovery and the effect of the injection parameters on displacement efficiency. The micromodel tests indicate that the penetration of the Alkaline solution into the crude oil and the subsequent formation of a water-in-oil (W/O) emulsion reduce the mobility of the water phase and divert the injected water into the unswept region, thereby improving the sweep efficiency. The sandpack flood results show that the tertiary oil recovery can reach about 20% of the initial oil in place (IOIP) using 1.0% NaOH, and the tertiary oil recovery has been found to increase as the Alkaline concentration increases. However, there is an optimum slug size and injection rate at which the highest tertiary oil recovery can be obtained during the Alkaline Flooding process. Continuous Alkaline injection can provide a higher tertiary oil recovery compared with a cyclic Alkaline injection pattern. These results show that the Alkaline Flooding, if properly designed and controlled, can lead to enhanced heavy oil recovery through the water-in-oil emulsification.

  • study on the variation of dynamic interfacial tension in the process of Alkaline Flooding for heavy oil
    Fuel, 2013
    Co-Authors: Haihua Pei, Guicai Zhang, Luchao Jin, Lei Ding
    Abstract:

    Abstract Experimental investigations have been conducted to elucidate the variation of the dynamic interfacial tension (DIFT) in the process of Alkaline Flooding for heavy oil. The Binnan heavy oil with high TAN (Total Acid Number) and the Zhuangxi heavy oil with low TAN were pre-equilibrated by long-term contacting with NaOH and Na 2 CO 3 solutions. The results show that the heavy oil pre-equilibrated by NaOH solutions almost loses the interfacial activity, and the IFT increases a lot. Although there is still interfacial activity in the heavy oil which is pre-equilibrated by Na 2 CO 3 solutions, and the dynamic interfacial tension minimum (DIFT min ) changes a little, yet the dynamic interfacial tension equilibrium value (DIFT eq ) increases a lot. The effect of interfacial reaction on the interfacial property of oil with low TAN is more severe than that with high TAN. When the Alkaline concentration is larger than a certain value, the IFT between the fresh oil with high TAN and the equilibrated Alkaline solutions can decrease to ultralow after interfacial reaction, and the Na 2 CO 3 system is superior to the NaOH system. However, the IFT between the fresh oil with low TAN and the equilibrated Alkaline solutions increases after interfacial reaction. The above results can be used as guidance in the formulation design and mechanisms studies of Alkaline Flooding for improved heavy oil recovery.

Qiang Liu - One of the best experts on this subject based on the ideXlab platform.

  • displacement mechanisms of enhanced heavy oil recovery by Alkaline Flooding in a micromodel
    Particuology, 2012
    Co-Authors: Mingzhe Dong, Qiang Liu
    Abstract:

    Abstract Enhanced oil recovery (EOR) by Alkaline Flooding for conventional oils has been extensively studied. For heavy oils, investigations are very limited due to the unfavorable mobility ratio between the water and oil phases. In this study, the displacement mechanisms of Alkaline Flooding for heavy oil EOR are investigated by conducting flood tests in a micromodel. Two different displacement mechanisms are observed for enhancing heavy oil recovery. One is in situ water-in-oil (W/O) emulsion formation and partial wettability alteration. The W/O emulsion formed during the injection of Alkaline solution plugs high permeability water channels, and pore walls are altered to become partially oil-wetted, leading to an improvement in sweep efficiency and high tertiary oil recovery. The other mechanism is the formation of an oil-in-water (O/W) emulsion. Heavy oil is dispersed into the water phase by injecting an Alkaline solution containing a very dilute surfactant. The oil is then entrained in the water phase and flows out of the model with the water phase.

  • wettability alteration by magnesium ion binding in heavy oil brine chemical sand systems analysis of electrostatic forces
    Journal of Petroleum Science and Engineering, 2007
    Co-Authors: Qiang Liu, Mingzhe Dong, Koorosh Asghari
    Abstract:

    Abstract In laboratory coreflood tests for enhanced heavy oil recovery by Alkaline Flooding, it was found that oil recovery was greatly affected by wettability alteration of sand. In this study, a heavy oil of 14°API was used to study the effect of the composition of the water phase on wettability alteration in the heavy oil/water/sand system. In micro-slide and micro-model tests, wettability change was observed. The presence of either Na 2 CO 3 or Mg 2+ alone in the water phase could not induce wettability alteration. When the water phase contained both Na 2 CO 3 and Mg 2+ , the water-wet sand became preferentially oil-wet by magnesium ion binding. The reduction in zeta (ζ)-potential value due to the addition of Mg 2+ into the heavy oil/Na 2 CO 3 solution/sand system confirmed the combination of Mg 2+ and ionized organic acids at the oil/water interface. In addition, the ζ-potential value of sand in the water phase suggested that Mg 2+ also adsorbed on sand surfaces, weakening the electrostatic forces. The reduction of repulsive electrostatic forces between oil drops and sand surfaces contributed to the wettability change of the sand from water-wet to more oil-wet.

  • surfactant enhanced Alkaline Flooding for western canadian heavy oil recovery
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007
    Co-Authors: Qiang Liu, Mingzhe Dong
    Abstract:

    Abstract For heavy oil reservoirs (with oil viscosities ranging from 1000 to more than 10,000 mPa s), primary production and waterFlooding can only recover 5–10% of initial oil in place (IOIP) due to the unfavorable mobility ratio between water phase and oil phase. If heavy oil is dispersed in formation brine by a chemical injection, the mobility of oil can be greatly improved. In this study, sandpack flood tests were conducted for a heavy oil sample with a viscosity of 1800 mPa s at 22 °C. The heavy oil was emulsified and entrained in formation brine by Alkaline/surfactant (A/S) Flooding and then produced out of the core. The results of sandpack flood tests showed that the tertiary oil recovery could reach 24% IOIP by injecting a 0.5 pore volume (PV) of chemical slug. The tertiary oil recovery did not decrease with the sandpack length. The experimental results showed that the formation of an oil-in-water (O/W) emulsion and an oil bank was necessary to improve the heavy oil recovery in sandpack flood tests. This is viable by injecting a chemical slug containing Na2CO3, NaOH, and a very dilute surfactant. Na2CO3/surfactant had synergistic enhancement in lowering interfacial tension, leading to the formation of O/W emulsion. The addition of NaOH accelerated the neutralization of organic acids in oil in sandpack flood tests so that the emulsified oil accumulated to produce an oil bank. When an oil bank was generated, the pressure drop along the sandpack responded significantly.

  • synergy of alkali and surfactant in emulsification of heavy oil in brine
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006
    Co-Authors: Qiang Liu, Mingzhe Dong, Xiangan Yue, Jirui Hou
    Abstract:

    Abstract The emulsification and entrainment of crude oil into displacing water is one of the mechanisms of Alkaline Flooding for conventional oil. If this mechanism is applied in heavy oil reservoirs, the flow of viscous oils and subsequently the oil recovery can be greatly improved. The formation brine of heavy oil reservoirs usually has a high salinity and high content of multiple cations that make the in situ emulsification of heavy oil a challenge. In this work, a heavy oil of 14° API is used to study the mechanism of emulsification of heavy oils in brine under slight interfacial disturbance. Emulsification tests and interfacial measurements are carried out to screen alkalis and surfactant additives for emulsifying the oil in the diluted formation brine. The results show that if only alkali or only surfactant is added into the brine, emulsification of the oil in brine cannot be triggered. When alkali (Na 2 CO 3 ) and very dilute surfactant are used together, the oil can be easily emulsified. The synergy of alkali and surfactant in emulsifying the heavy oil in brine is investigated by measuring the dynamic interfacial tension (IFT) and zeta-potential of emulsions. It is found that the interaction of added surfactant and in situ surfactant from the reaction of alkali and organic acids in oil can significantly reduce the dynamic interfacial tension between oil and water and increase the surface charge density of emulsions. The synergistic enhancement between alkali and surfactant is the key mechanism of emulsifying heavy oils in brine under slight interfacial disturbance.

Luchao Jin - One of the best experts on this subject based on the ideXlab platform.

  • potential of Alkaline Flooding to enhance heavy oil recovery through water in oil emulsification
    Fuel, 2013
    Co-Authors: Haihua Pei, Guicai Zhang, Luchao Jin
    Abstract:

    Abstract Alkaline Flooding has great potential for enhancing the recovery of heavy oil, especially for reservoirs in which thermal methods are not suitable. In this study, Alkaline Flooding tests were performed in micromodels and sandpacks to investigate the microscopic displacement mechanisms for enhancing heavy oil recovery and the effect of the injection parameters on displacement efficiency. The micromodel tests indicate that the penetration of the Alkaline solution into the crude oil and the subsequent formation of a water-in-oil (W/O) emulsion reduce the mobility of the water phase and divert the injected water into the unswept region, thereby improving the sweep efficiency. The sandpack flood results show that the tertiary oil recovery can reach about 20% of the initial oil in place (IOIP) using 1.0% NaOH, and the tertiary oil recovery has been found to increase as the Alkaline concentration increases. However, there is an optimum slug size and injection rate at which the highest tertiary oil recovery can be obtained during the Alkaline Flooding process. Continuous Alkaline injection can provide a higher tertiary oil recovery compared with a cyclic Alkaline injection pattern. These results show that the Alkaline Flooding, if properly designed and controlled, can lead to enhanced heavy oil recovery through the water-in-oil emulsification.

  • study on the variation of dynamic interfacial tension in the process of Alkaline Flooding for heavy oil
    Fuel, 2013
    Co-Authors: Haihua Pei, Guicai Zhang, Luchao Jin, Lei Ding
    Abstract:

    Abstract Experimental investigations have been conducted to elucidate the variation of the dynamic interfacial tension (DIFT) in the process of Alkaline Flooding for heavy oil. The Binnan heavy oil with high TAN (Total Acid Number) and the Zhuangxi heavy oil with low TAN were pre-equilibrated by long-term contacting with NaOH and Na 2 CO 3 solutions. The results show that the heavy oil pre-equilibrated by NaOH solutions almost loses the interfacial activity, and the IFT increases a lot. Although there is still interfacial activity in the heavy oil which is pre-equilibrated by Na 2 CO 3 solutions, and the dynamic interfacial tension minimum (DIFT min ) changes a little, yet the dynamic interfacial tension equilibrium value (DIFT eq ) increases a lot. The effect of interfacial reaction on the interfacial property of oil with low TAN is more severe than that with high TAN. When the Alkaline concentration is larger than a certain value, the IFT between the fresh oil with high TAN and the equilibrated Alkaline solutions can decrease to ultralow after interfacial reaction, and the Na 2 CO 3 system is superior to the NaOH system. However, the IFT between the fresh oil with low TAN and the equilibrated Alkaline solutions increases after interfacial reaction. The above results can be used as guidance in the formulation design and mechanisms studies of Alkaline Flooding for improved heavy oil recovery.

  • analysis of microscopic displacement mechanisms of Alkaline Flooding for enhanced heavy oil recovery
    Energy & Fuels, 2011
    Co-Authors: Haihua Pei, Guicai Zhang, Luchao Jin, Xiaoling Liu
    Abstract:

    In this study, the microscopic displacement mechanisms of Alkaline Flooding for enhanced heavy-oil recovery are investigated using a micromodel. It has been observed that Alkaline Flooding exhibits a better sweep efficiency than waterFlooding, and the serious viscous fingering is significantly reduced. The main microscopic mechanisms of Alkaline Flooding for enhanced heavy-oil recovery are that the Alkaline solution penetrates in crude oil and water drops are, subsequently, formed inside the oil phase, which can improve the mobility ratio and, thus, lead to the improvement of sweep efficiency. The higher the Alkaline concentration, the more easily the Alkaline solution penetrates in the oil phase. Therefore, a greater improvement in sweep efficiency can be obtained using a higher concentration of alkali. The primary mechanism of the formation of the water drop inside the oil phase during Alkaline Flooding is related to the interfacial interaction between alkali and heavy oil, which not only results in the...