The vacuum residual from Iranian Light crude oil are separated into a series of 16 narrow fractions according to the molecular weight by the supercritical fluid extraction and fractional (SFEF) technology. The chemica...The vacuum residual from Iranian Light crude oil are separated into a series of 16 narrow fractions according to the molecular weight by the supercritical fluid extraction and fractional (SFEF) technology. The chemical element and the UV spectrum of each fraction are analyzed. The effects of several factors on the interfacial tension are investigated, which are the fraction concentration in oil phase, the ratio of oil component, the salts dissolved in the water phase and the pH value. The interfacial tension decreases rapidly as the concentration of the residual fraction in the oil increases, showing a higher interfacial activity of the fraction. The interfacial tension changes, as the amount of absorption or the state of the fractions in the interface changes resulting from different ratios of oil, different kinds or concentrations of salts in water, and different pH values. It is concluded that the interfacial tension changes regularly, corresponding to the regular molecular parameters of the vacuum residual fractions.展开更多
Surface active ionic liquids (SAILs) are considered as prominent materials in enhanced oil recovery thanks to their high interfacial activity. This study reports the preparation and applications of a nanostructure Tri...Surface active ionic liquids (SAILs) are considered as prominent materials in enhanced oil recovery thanks to their high interfacial activity. This study reports the preparation and applications of a nanostructure Tripodal imidazolium SAIL as an environmentally-friendly substitute to the conventional surfactants. The product has a star-like molecular structure centered by a triazine spacer, namely [(C_(4)im)_(3)TA][Cl_(3)], prepared by a one-step synthesis method and characterized with FT-IR, NMR, XRD, and SEM analysis methods. The interfacial tension of the system was decreased to about 78% at critical micelle concentration of less than 0.08 mol·dm^(−3). Increasing temperature, from 298.2 to 323.2 K, improved this capability. The solid surface wettability was changed from oil-wet to water-wet and 80% and 77% stable emulsions of crude oil–aqueous solutions were created after one day and one week, respectively. Compared to the Gemini kind homologous SAILs, the superior effects of the Tripodal SAIL were revealed and attributed to the strong hydrophobic branches in the molecule. The Frumkin adsorption isotherm precisely reproduced the generated IFT data, and accordingly, the adsorption and thermodynamic parameters were determined.展开更多
The e ects of CO2 and salt type on the interfacial tension(IFT) between crude oil and carbonated brine(CB) have not been fully understood. This study focuses on measuring the dynamic IFT between acidic crude oil with ...The e ects of CO2 and salt type on the interfacial tension(IFT) between crude oil and carbonated brine(CB) have not been fully understood. This study focuses on measuring the dynamic IFT between acidic crude oil with a total acid number of 1.5 mg KOH/g and fully CO2-saturated aqueous solutions consisting of 15,000 ppm of KCl, NaCl, CaCl2 and MgCl2 at 30 °C and a wide range of pressures(500–4000 psi). The results of IFT measurements showed that solvation of CO2 into all the studied aqueous solutions led to an increase in IFT of acidic crude oil(i.e., comparison of IFT of crude oil/CB and crude oil/brine), while no significant e ect was observed for pressure. In contrast, the obtained results of studied salts indicated a positive e ect on the IFT reduction of acidic crude oil/carbonated water(CW)(i.e., comparison of IFT of crude oil/CB and crude oil/CW).展开更多
Alkaline-surfactant-polymer (ASP) flooding using sodium hydroxide as the alkali component to enhance oil recovery in Daqing Oilfield, northeast China has been successful, but there are new problems in the treatment ...Alkaline-surfactant-polymer (ASP) flooding using sodium hydroxide as the alkali component to enhance oil recovery in Daqing Oilfield, northeast China has been successful, but there are new problems in the treatment of produced crude. The alkali added forms stable water-in-crude oil emulsion, hence de-emulsification process is necessary to separate oil and water. The problems in enhanced oil recovery with ASP flooding were investigated in laboratory by using fractions of Daqing crude oil. The oil was separated into aliphatics, aromatics, resin and asphaltene fractions. These fractions were then mixed with an additive-free jet fuel to form model oils. The interfacial properties, such as interfacial tension and interracial pressure of the systems were also measured, which together with the molecular parameters of the fractions were all used to investigate the problems in the enhanced oil recovery. In our work, it was found that sodium hydroxide solution reacts with the acidic hydrogen in the fractions of crude oil and forms soap-like interfacially active components, which accumulate at the crude oil-water interface.展开更多
Surfactants are widely used in the petroleum industry as one kind of Enhanced Oil Recovery methods (EOR). The oil sands mines in Northern Alberta are the largest one in the world. Due to using sodium hydroxide in bitu...Surfactants are widely used in the petroleum industry as one kind of Enhanced Oil Recovery methods (EOR). The oil sands mines in Northern Alberta are the largest one in the world. Due to using sodium hydroxide in bitumen extraction process, there are a lot of surfactant molecules in the tailing water. The surfactants from oil sands industry have brought a potential threat to the environment and human health. Depending on the performance of surfactant at the interface, this work focuses on removing these harmful surfactants from the tailing water and not bringing other possible hazardous substances. Moreover, a mathematical model is built to calculate the removal efficiency of the surfactant. The time required for removing the surfactant is determined experimentally. In conclusion, most of surfactant molecules are adsorbed at the oil/water interface. The fraction of the surfactant staying at the oil/water interface is high. Most of the surfactants in tailing water can be eliminated. The time of surfactant migration can be used for setting up the update time of the oil film in the automatic instrument, which can be designed in the future.展开更多
Polymer microspheres(PMs),such as polyacrylamide,have been widely applied for enhanced oil recovery(EOR),yet with environmental concerns.Here,we report a microfluid displacement technology containing a bio-based eco-f...Polymer microspheres(PMs),such as polyacrylamide,have been widely applied for enhanced oil recovery(EOR),yet with environmental concerns.Here,we report a microfluid displacement technology containing a bio-based eco-friendly material,i.e.,calcium alginate(CaAlg)microspheres for EOR.Two dominant mechanisms responsible for EOR over Ca Alg fluid have been verified,including the microscopic oil displacement efficacy augmented by regulating capillary force(determined by the joint action of interfacial tension and wettability between different phases)and macroscopic sweep volume increment through profile control and mobility ratio reduction.This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate(SDS).The core flooding and nuclear magnetic resonance(NMR)tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation(wettability alteration and IFT reduction)and rheology properties,enabling simultaneous profile control and oil displacement.Excessive introduction of SDS will have a negative impact on rheological properties,which is not favored for EOR.Our results show that the involvement of 4-m M SDS will provide the best behavior,with an EOR rate of 34.38%.This cost-effective and environmentally-friendly bio-microspherebased microfluidic displacement technology is expected to achieve“green”oil recovery in future oilfield exploitation.展开更多
Surfactant flooding is an enhanced oil recovery(EOR)method for recovering residual oil in the reservoir through mechanism of interfacial tension(IFT)reduction and wettability alteration.Due to toxicity and high cost a...Surfactant flooding is an enhanced oil recovery(EOR)method for recovering residual oil in the reservoir through mechanism of interfacial tension(IFT)reduction and wettability alteration.Due to toxicity and high cost associated with conventional surfactants,recent research has focussed on developing low-cost and environmentally benign surfactants.Herein,a low-cost green surfactant is extracted from Vernonia Amygdalina(VA)and appraised for EOR applications.The extracted surfactant was characterized using Fourier Transform Infrared(FTIR)and High-Pressure Liquid Chromatography(HPLC).The IFT of the synthesized surfactant at the oil-water interface was determined using Kruss tensiometer.Additionally,the foam stability of the synthesized surfactant was examined.Moreover,the wettability of the saponin based natural surfactant(SBNS)at the rock-fluid interface was analysed using Dataphysics drop shape analyser.Experimental result revealed that SBNS(1 wt%concentration)stabilized foam for longer periods with half-life of 1100 min.Furthermore,the synthesized surfactant was effective in lowering the IFT of oil-water interface from 18 mN/m to 0.97 mN/m.Finally,SBNS altered the wettability of sandstone cores to water-wetting condition by reducing the contact angle from 118.5° to 45.7°.Overall,SBNS exhibit excellent properties desirable for EOR and thereby recommended as supplementary alternative to conventional surfactants.展开更多
In recent years,production from tight oil reservoirs has increasingly supplemented production from conventional oil resources.Oil-wet formations account for a considerable proportion of tight oil reservoirs.Surfactant...In recent years,production from tight oil reservoirs has increasingly supplemented production from conventional oil resources.Oil-wet formations account for a considerable proportion of tight oil reservoirs.Surfactant can change wettability and reduce interfacial tension,thus resulting in a better oil recovery.In this manuscript,a nonionic surfactant was introduced for tight oil-wet reservoirs.The oil recovery in the oil-wet sandstone due to spontaneous imbibition was 8.59%lower than that of the waterwet sandstone due to surfactant.The 0.1%surfactant solution corresponded to the highest imbibition recovery rate of 27.02%from the oil-wet sample.With the surfactant treatment,the treated core quickly changed from weakly oil-wet to weakly water-wet.The capillary force acted as the driving force and promoted imbibition.The optimal surfactant adsorption quantity in the oil-wet sandstone was observed in the sample at concentrations ranging from 0.1%to 0.3%,which also corresponded to the highest oil recovery.Analysis of the inverse Bond number NB-1 suggested that the driving force was gravity for brine imbibition in the oil-wet cores and that it was capillary force for surfactant imbibition in the oil-wet cores.When the surfactant concentration was lower than the critical micelle concentration,the surfactant concentration was negatively correlated with the inverse Bond number and positively correlated with the oil recovery rate.When the surfactant concentration was higher than the critical micelle concentration,the oil recovery increased with a smaller interfacial tension.Nuclear magnetic resonance suggested that the movable pore and pore throat size in the oil-wet sample decreased from 0.363 mm in the untreated rock to 0.326 mm with the surfactant treatment,which indicated that the surfactant improved the flow capacity of the oil.The findings of this study can help to better understand the adsorption impact of surfactants on the characteristics of the oil/water and solid/liquid interfaces.The imbibition mechanism in oil-wet tight sandstone reservoirs was further revealed.These systematic approaches help to select appropriate surfactants for better recovery in oil-wet tight sandstone reservoirs through imbibition.展开更多
In recent years,controlling the salinity and composition of the injected water has become an emerging enhanced oil recovery(EOR)technique,often described as low salinity(LS)waterflooding.This work is done with the int...In recent years,controlling the salinity and composition of the injected water has become an emerging enhanced oil recovery(EOR)technique,often described as low salinity(LS)waterflooding.This work is done with the intention to contribute to the ongoing discussions about LS waterflooding mechanism(s).For this purpose,a series of different experiments were conducted.At first,the effect of salinity on the interfacial tension(IFT)and the contact angle was evaluated with a crude oil sample.Then to achieve more accurate results in observing oil/water interface,similar IFT experiments were also carried out on a synthetic oil containing asphaltenes.Thereafter,microscopic visualization using glass micromodel was performed on the interface of the synthetic oil sample and brines.Four brine solutions including Sea Water(SW),it's dilutions and formation water(FW)were used for various experiments.Finally,to investigate the presented mechanism by other authors,a series of Environmental Scanning Electron Microscopy(ESEM)analysis on the synthetic oil was carried out to understand better the phase behaviour after contacting both synthetic oil and water phases from the micromodel experiment.Based on the existing mechanism,there exists an optimal concentration beyond which dilution is no longer an effective process.展开更多
Surfactant-based oil recovery processes are employed to lower the interfacial tension in immiscible displacement processes,change the wettability of rock to a more water-wet system and emulsify the oil to displace it ...Surfactant-based oil recovery processes are employed to lower the interfacial tension in immiscible displacement processes,change the wettability of rock to a more water-wet system and emulsify the oil to displace it in subsurface porous media.Furthermore,these phenomena can reduce the capillary pressure and enhance spontaneous imbibition.The key factors affecting such immiscible displacement process are temperature,salinity and p H of the fluids,surfactant concentration and adsorption.Therefore,before any surfactant flooding process is applied,extensive studies of fluid-fluid and rock-fluid interactions are needed.The use of other chemicals along with surfactants in chemical enhanced oil recovery(c EOR)processes have been widely considered to exploit the synergy of individual chemicals and complement the weakness arises from each of them during immiscible displacement of fluids in porous media.Therefore,such combinations of chemicals lead to alkaline-surfactant(AS),surfactantpolymer(SP),alkaline-surfactant-polymer(ASP),and nanoparticle-surfactant(NS)flooding processes,among others.In this review study,we categorised the role and displacement mechanisms of surfactants and discussed the key factors to be considered for analysing the fluid displacement in porous media.展开更多
Nanofluids because of their surface characteristics improve the oil production from reservoirs by enabling different enhanced recovery mechanisms such as wettability alteration,interfacial tension(IFT)reduction,oil vi...Nanofluids because of their surface characteristics improve the oil production from reservoirs by enabling different enhanced recovery mechanisms such as wettability alteration,interfacial tension(IFT)reduction,oil viscosity reduction,formation and stabilization of colloidal systems and the decrease in the asphaltene precipitation.To the best of the authors’ knowledge,the synthesis of a new nanocomposite has been studied in this paper for the first time.It consists of nanoparticles of both SiO2 and Fe3O4.Each nanoparticle has its individual surface property and has its distinct effect on the oil production of reservoirs.According to the previous studies,Fe3O4 has been used in the prevention or reduction of asphaltene precipitation and SiO2 has been considered for wettability alteration and/or reducing IFTs in enhanced oil recovery.According to the experimental results,the novel synthesized nanoparticles have increased the oil recovery by the synergistic effects of the formed particles markedly by activating the various mechanisms relative to the use of each of the nanoparticles in the micromodel individually.According to the results obtained for the use of this nanocomposite,understanding reservoir conditions plays an important role in the ultimate goal of enhancing oil recovery and the formation of stable emulsions plays an important role in oil recovery using this method.展开更多
In this work, an experimental study combined with numerical simulation was conducted to investigate the potential of chemically enhanced water alternating gas (CWAG) injection as a new enhanced oil recovery method. ...In this work, an experimental study combined with numerical simulation was conducted to investigate the potential of chemically enhanced water alternating gas (CWAG) injection as a new enhanced oil recovery method. The unique feature of this new method is that it uses alkaline, surfactant, and polymer additives as a chemical slug which is injected during the water alternating gas (WAG) process to reduce the interfacial tension (IFT) and simultaneously improve the mobility ratio. In essence, the proposed CWAG process involves a combination of chemical flooding and immiscible carbon dioxide (CO2) injection and helps in IFT reduction, water blocking reduction, mobility control, oil swelling, and oil viscosity reduction due to CO2 dissolution. Its performance was compared with the conventional immiscible water alter- nating gas (I-WAG) flooding. Oil recovery utilizing CWAG was better by 26 % of the remaining oil in place after waterflooding compared to the recovery using WAG conducted under similar conditions. The coreflood data (cumulative oil and water production) were history mat- ched via a commercial simulator by adjusting the relative permeability curves and assigning the values of the rock and fluid properties such as porosity, permeability, and the experimentally determined IFT data. History matching ofthe coreflood model helped us optimize the experiments and was useful in determining the importance of the parameters influencing sweep efficiency in the CWAG process. The effectiveness of the CWAG process in pro- viding enhancement of displacement efficiency is evident in the oil recovery and pressure response observed in the coreflood. The results of sensitivity analysis on CWAG slug patterns show that the alkaline-surfactant-polymer injection is more beneficial after CO2 slug injection due to oil swelling and viscosity reduction. The CO2 slug size analysis shows that there is an optimum CO2 slug size, around 25 % pore volume which leads to a maximum oil recovery in the CWAG process. This study shows that the ultralow IFT system, i.e., IFT equaling 10 2 or 10 3 mN/ m, is a very important parameter in CWAG process since the water blocking effect can be minimized.展开更多
This study investigated experimentally the coupled effects of hydrophilic SiO_(2) nanoparticles(NPs)and low-salinity water(LSW)on the wettability of synthetic clay-free Berea sandstone.Capillary pressure,interfacial t...This study investigated experimentally the coupled effects of hydrophilic SiO_(2) nanoparticles(NPs)and low-salinity water(LSW)on the wettability of synthetic clay-free Berea sandstone.Capillary pressure,interfacial tension(IFT),contact angle,Zeta potential,and dynamic displacement measurements were performed at various NP mass fractions and brine salinities.The U.S.Bureau of Mines(USBM)index was used to quantify the wettability alteration.Furthermore,the NP stability and retention and the effect of enhanced oil recovery by nanofluid were examined.The results showed that LSW immiscible displacement with NPs altered the wettability toward more water wet.With the decreasing brine salinity and increasing NP mass fraction,the IFT and contact angle decreased.The wettability alteration intensified most as the brine salinity decreased to 4000 mg/L and the NP mass fraction increased to 0.075%.Under these conditions,the resulting incremental oil recovery factor was approximately 13 percentage points.When the brine salinity was 4000 mg/L and the NP mass fraction was 0.025%,the retention of NPs caused the minimum damage to permeability.展开更多
In order to improve oil recovery, Enhanced Oil Recovery (EOR) techniques have been applied to several light and medium oil reservoirs. This research was directed towards the development of chemical flooding methods fo...In order to improve oil recovery, Enhanced Oil Recovery (EOR) techniques have been applied to several light and medium oil reservoirs. This research was directed towards the development of chemical flooding methods for such reservoirs. The main objective of this experimental work was to investigate the efficiency of introducing various types of Ionic Liquids (ILs), 1-Ethyl-3-methylimidazolium Chloride [EMIM][Cl], 1-Benzyl-3-methylimidazolium Chloride [BenzMIM][Cl], and Trihexyltetradecylphosphonium Chloride [THTDPh][Cl] on the Recovery Factor (RF) of medium oil (Weyburn oil, 30.25 API°) at room temperature. The series of flooding experiments were carried out by introducing a slug of IL mixtures. Results demonstrated that maximum oil recovery factor was obtained when [EMIM][Cl] was added in the displacing fluid. Further investigations have been conducted to examine the effect of ILs concentrations on the recovery mechanisms by measuring Surface Tension (SFT), pH, and viscosity of the displacing phases. Finally, the effect of theses ILs in wettability alteration was examined.展开更多
A novel nanofluid of modified carbon black(MCB)nanoparticles was initially developed for enhanced oil recovery(EOR)in low permeability reservoirs.The MCB nanoparticles were obtained via a three-step reaction involving...A novel nanofluid of modified carbon black(MCB)nanoparticles was initially developed for enhanced oil recovery(EOR)in low permeability reservoirs.The MCB nanoparticles were obtained via a three-step reaction involving modification by oxidation,acyl chlorination,and activated grafting.MCB nano-particles were spherically dispersed,with an average size of 72.3 nm.Compared with carbon black(CB)nanoparticles,dispersed MCB nanoparticles can effectively reduce the oil-water interfacial tension(IFT)to 10^(-2)mN/m and change the surface wettability of sand particles.Based on the results of core flooding experiments,the MCB nanoparticles exhibited a better EOR capacity than surfactants and CB nano-particles,and the final oil recovery was significantly increased by 27.27%.The core scanning test showed that the MCB nanoparticles could plug high permeability channels by adsorbing onto the surfaces of sand particles and forming larger aggregates that bridge across pores or throats,resulting in a higher swept volume.The synergistic effects of improved swept volume and oil displacement efficiency were the EOR mechanisms of the MCB nanoparticles.The studies indicate that these MCB nanoparticles have excellent potential for EOR in low permeability reservoirs.展开更多
A new ultra-long chain monounsaturated 4-(N-nervonicamidopropyl-N,N-dimethylammonium)butane sulfonate(NDAS)zwitterionic surfactant with ultralow interfacial tensions was developed through the modification of nervonic ...A new ultra-long chain monounsaturated 4-(N-nervonicamidopropyl-N,N-dimethylammonium)butane sulfonate(NDAS)zwitterionic surfactant with ultralow interfacial tensions was developed through the modification of nervonic acid derived from renewable non-edible seed oils by a simple and effective method.Its structure was characterized by ESI-HRMS,1 H NMR,and 13 C NMR.NDAS surfactant exhibited a strong interfacial activity(~10^(-4) mN/m)between the crude oil and the formation brine at a very low surfactant dosage(0.05 g/L)and at high salinity conditions,which is equivalent to 2%(w/w)of dosage of the most traditional surfactants used in the enhanced oil recovery field.Meanwhile,at a very low concentration(0.05 g/L),NDAS demonstrated strong NaCl compatibility up to 100 g/L,Ca^(2+)ions compatibility up to 200 mg/L,and temperature stability up to 90℃.The surface tension,emulsification,and biodegradability parameters were also evaluated.This work consolidates our hypothesis that increasing the hydrophobic chain length of a surfactant certainly contributes to the high interfacial activity and good compatibility of salts and temperatures.Hence,it will facilitate the design of a sustainable alternative to petroleum-based chemicals to develop bio-based surfactants and extend the domain of bio-based surfactants to new applications such as in enhanced oil recovery(EOR).展开更多
The main advantages of the use of ionic liquids in enhanced oil recovery are their tunability and stability in harsh environmental conditions. In this work, a comprehensive review of ionic liquids proposed to improve ...The main advantages of the use of ionic liquids in enhanced oil recovery are their tunability and stability in harsh environmental conditions. In this work, a comprehensive review of ionic liquids proposed to improve current chemical oil recovery methods has been presented, focusing on core flooding experiments. With an almost infinite number of possible ionic liquids, the amount of experiments carried out up to now has been very limited. However, results are promising, with additional recovery after secondary flooding of up to 32% of the original oil in place. Most formulations with ionic liquids have been proposed for sandstone reservoirs, the number of studies with carbonate cores being very scarce. The possibilities of a new room temperature surface active ionic liquid, 1-decyl-3-methylimidazolium triflate,for this application were analyzed. It was shown that it is able to drastically reduce the water/oil interfacial tension. An optimized formulation was proposed for carbonate reservoirs. After secondary flooding with brine, an additional recovery of 10.5% of original oil in place was achieved at room conditions. A combination of the proposed method followed by a polymer flooding step with polyacrylamide led to a lesser but still significant recovery, reducing the costs associated to the ionic liquid.展开更多
The switchable oil layer driven by electrowetting gives visible color and light valve control, which is the basis of Electro-Fluidic Displays. The colored oil’s property is a key factor that influences the Electro-Fl...The switchable oil layer driven by electrowetting gives visible color and light valve control, which is the basis of Electro-Fluidic Displays. The colored oil’s property is a key factor that influences the Electro-Fluidic Displays switching behavior. A purple oil was formulated by the oil-soluble purple dye in decane in this study. The dye molecule itself is nonpolar and it doesn’t dissolve in water. The concentration of colored oil influenced the oil/water interfacial tension and oil viscosity. The relationship of EFD switching behavior with oil/water interfacial tension, oil viscosity, and oil conductivity has been systematically investigated. The oil/water interfacial tension decreased with increasing oil concentration, in the meanwhile, the conductivity increased. Oil conductivity was one of the key factors that influenced the Electro-Fluidic Displays optical property. We found for the first time that at the lower oil concentration (2% - 10%), the interfacial tension plays a main role effect on the rupture voltage and response time, but as the conductivity of higher concentration of colored oil increased (at 20%), the rupture voltage-controlled both by conductivity and interfacial tension.展开更多
In chemical enhanced oil recovery, surfactants are injected into the reservoir with the intention to lower interfacial tension (IFT) between the water and oil phases, and thereby bring about efficient displacement of ...In chemical enhanced oil recovery, surfactants are injected into the reservoir with the intention to lower interfacial tension (IFT) between the water and oil phases, and thereby bring about efficient displacement of oil. However, the adsorption of the surfactants to reservoir rock surfaces leads to the loss and reduction in concentration of the surfactants, which in turn reduces the overall efficiency of the oil recovery process, with attendant financial losses. In this work, the adsorption of Quillaja Saponaria (QS), a novel, natural, non-ionic surfactant, on crushed sandstone reservoir rock is investigated. X-ray diffraction (XRD) study of clean sandstone particles has been undertaken to determine the main components present in the sand particles. The conductivity method was used to measure CMC and the surfactant concentrations in aqueous solutions. Batch adsorption experiments were used to determine the amount of QS adsorbed on rock surface. Equilibrium conditions were reached after almost 5 days. From the results of the study, the Langmuir isotherm model is more suited for predicting the adsorption behaviour of QS on sandstone. The kinetic adsorption of QS obeys the pseudo-second order model. This study is particularly relevant in surfactant selection for chemical EOR processes.展开更多
基金Supported by the National Key Basic Research Programme (No.973-G1999022505),University of Petroleum Basic Research Fund(No.ZX9904)
文摘The vacuum residual from Iranian Light crude oil are separated into a series of 16 narrow fractions according to the molecular weight by the supercritical fluid extraction and fractional (SFEF) technology. The chemical element and the UV spectrum of each fraction are analyzed. The effects of several factors on the interfacial tension are investigated, which are the fraction concentration in oil phase, the ratio of oil component, the salts dissolved in the water phase and the pH value. The interfacial tension decreases rapidly as the concentration of the residual fraction in the oil increases, showing a higher interfacial activity of the fraction. The interfacial tension changes, as the amount of absorption or the state of the fractions in the interface changes resulting from different ratios of oil, different kinds or concentrations of salts in water, and different pH values. It is concluded that the interfacial tension changes regularly, corresponding to the regular molecular parameters of the vacuum residual fractions.
基金The authors would like to acknowledge the Bu Ali Sina University and the Iran National Science Foundation:INSF,under Grant number of 99031559,for their financial supports.
文摘Surface active ionic liquids (SAILs) are considered as prominent materials in enhanced oil recovery thanks to their high interfacial activity. This study reports the preparation and applications of a nanostructure Tripodal imidazolium SAIL as an environmentally-friendly substitute to the conventional surfactants. The product has a star-like molecular structure centered by a triazine spacer, namely [(C_(4)im)_(3)TA][Cl_(3)], prepared by a one-step synthesis method and characterized with FT-IR, NMR, XRD, and SEM analysis methods. The interfacial tension of the system was decreased to about 78% at critical micelle concentration of less than 0.08 mol·dm^(−3). Increasing temperature, from 298.2 to 323.2 K, improved this capability. The solid surface wettability was changed from oil-wet to water-wet and 80% and 77% stable emulsions of crude oil–aqueous solutions were created after one day and one week, respectively. Compared to the Gemini kind homologous SAILs, the superior effects of the Tripodal SAIL were revealed and attributed to the strong hydrophobic branches in the molecule. The Frumkin adsorption isotherm precisely reproduced the generated IFT data, and accordingly, the adsorption and thermodynamic parameters were determined.
文摘The e ects of CO2 and salt type on the interfacial tension(IFT) between crude oil and carbonated brine(CB) have not been fully understood. This study focuses on measuring the dynamic IFT between acidic crude oil with a total acid number of 1.5 mg KOH/g and fully CO2-saturated aqueous solutions consisting of 15,000 ppm of KCl, NaCl, CaCl2 and MgCl2 at 30 °C and a wide range of pressures(500–4000 psi). The results of IFT measurements showed that solvation of CO2 into all the studied aqueous solutions led to an increase in IFT of acidic crude oil(i.e., comparison of IFT of crude oil/CB and crude oil/brine), while no significant e ect was observed for pressure. In contrast, the obtained results of studied salts indicated a positive e ect on the IFT reduction of acidic crude oil/carbonated water(CW)(i.e., comparison of IFT of crude oil/CB and crude oil/CW).
文摘Alkaline-surfactant-polymer (ASP) flooding using sodium hydroxide as the alkali component to enhance oil recovery in Daqing Oilfield, northeast China has been successful, but there are new problems in the treatment of produced crude. The alkali added forms stable water-in-crude oil emulsion, hence de-emulsification process is necessary to separate oil and water. The problems in enhanced oil recovery with ASP flooding were investigated in laboratory by using fractions of Daqing crude oil. The oil was separated into aliphatics, aromatics, resin and asphaltene fractions. These fractions were then mixed with an additive-free jet fuel to form model oils. The interfacial properties, such as interfacial tension and interracial pressure of the systems were also measured, which together with the molecular parameters of the fractions were all used to investigate the problems in the enhanced oil recovery. In our work, it was found that sodium hydroxide solution reacts with the acidic hydrogen in the fractions of crude oil and forms soap-like interfacially active components, which accumulate at the crude oil-water interface.
文摘Surfactants are widely used in the petroleum industry as one kind of Enhanced Oil Recovery methods (EOR). The oil sands mines in Northern Alberta are the largest one in the world. Due to using sodium hydroxide in bitumen extraction process, there are a lot of surfactant molecules in the tailing water. The surfactants from oil sands industry have brought a potential threat to the environment and human health. Depending on the performance of surfactant at the interface, this work focuses on removing these harmful surfactants from the tailing water and not bringing other possible hazardous substances. Moreover, a mathematical model is built to calculate the removal efficiency of the surfactant. The time required for removing the surfactant is determined experimentally. In conclusion, most of surfactant molecules are adsorbed at the oil/water interface. The fraction of the surfactant staying at the oil/water interface is high. Most of the surfactants in tailing water can be eliminated. The time of surfactant migration can be used for setting up the update time of the oil film in the automatic instrument, which can be designed in the future.
基金supported by the Open Fund of Shaanxi Key Laboratory of Advanced Stimulation Technology for Oil&Gas Reservoirs(No.KFJJ-TZ-2020-2)the National Natural Science Foundation of China(No.52104030)+1 种基金the Key Research and Development Program of Shaanxi(No.2022 KW-35)the China Fundamental Research Funds for the Central Universities。
文摘Polymer microspheres(PMs),such as polyacrylamide,have been widely applied for enhanced oil recovery(EOR),yet with environmental concerns.Here,we report a microfluid displacement technology containing a bio-based eco-friendly material,i.e.,calcium alginate(CaAlg)microspheres for EOR.Two dominant mechanisms responsible for EOR over Ca Alg fluid have been verified,including the microscopic oil displacement efficacy augmented by regulating capillary force(determined by the joint action of interfacial tension and wettability between different phases)and macroscopic sweep volume increment through profile control and mobility ratio reduction.This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate(SDS).The core flooding and nuclear magnetic resonance(NMR)tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation(wettability alteration and IFT reduction)and rheology properties,enabling simultaneous profile control and oil displacement.Excessive introduction of SDS will have a negative impact on rheological properties,which is not favored for EOR.Our results show that the involvement of 4-m M SDS will provide the best behavior,with an EOR rate of 34.38%.This cost-effective and environmentally-friendly bio-microspherebased microfluidic displacement technology is expected to achieve“green”oil recovery in future oilfield exploitation.
基金The authors would like to thank the Ministry of Higher Education(MOHE)Malaysia and Universiti Teknologi Malaysia(UTM)for theirfinancial support through Research Management Grants Vot.No.R.J130000.3551.07G52,R.J130000.3551.06G68&06G69.
文摘Surfactant flooding is an enhanced oil recovery(EOR)method for recovering residual oil in the reservoir through mechanism of interfacial tension(IFT)reduction and wettability alteration.Due to toxicity and high cost associated with conventional surfactants,recent research has focussed on developing low-cost and environmentally benign surfactants.Herein,a low-cost green surfactant is extracted from Vernonia Amygdalina(VA)and appraised for EOR applications.The extracted surfactant was characterized using Fourier Transform Infrared(FTIR)and High-Pressure Liquid Chromatography(HPLC).The IFT of the synthesized surfactant at the oil-water interface was determined using Kruss tensiometer.Additionally,the foam stability of the synthesized surfactant was examined.Moreover,the wettability of the saponin based natural surfactant(SBNS)at the rock-fluid interface was analysed using Dataphysics drop shape analyser.Experimental result revealed that SBNS(1 wt%concentration)stabilized foam for longer periods with half-life of 1100 min.Furthermore,the synthesized surfactant was effective in lowering the IFT of oil-water interface from 18 mN/m to 0.97 mN/m.Finally,SBNS altered the wettability of sandstone cores to water-wetting condition by reducing the contact angle from 118.5° to 45.7°.Overall,SBNS exhibit excellent properties desirable for EOR and thereby recommended as supplementary alternative to conventional surfactants.
基金financially supported by the National Key R&D Program of China(No.2019YFA0708700)National Science Fund of China(No.51804327,51834010)+1 种基金Climb Taishan Scholar Program in Shandong Province(No.tspd20161004)the Fundamental Research Funds for the Central Universities(No.18CX02026A,24720182026A)。
文摘In recent years,production from tight oil reservoirs has increasingly supplemented production from conventional oil resources.Oil-wet formations account for a considerable proportion of tight oil reservoirs.Surfactant can change wettability and reduce interfacial tension,thus resulting in a better oil recovery.In this manuscript,a nonionic surfactant was introduced for tight oil-wet reservoirs.The oil recovery in the oil-wet sandstone due to spontaneous imbibition was 8.59%lower than that of the waterwet sandstone due to surfactant.The 0.1%surfactant solution corresponded to the highest imbibition recovery rate of 27.02%from the oil-wet sample.With the surfactant treatment,the treated core quickly changed from weakly oil-wet to weakly water-wet.The capillary force acted as the driving force and promoted imbibition.The optimal surfactant adsorption quantity in the oil-wet sandstone was observed in the sample at concentrations ranging from 0.1%to 0.3%,which also corresponded to the highest oil recovery.Analysis of the inverse Bond number NB-1 suggested that the driving force was gravity for brine imbibition in the oil-wet cores and that it was capillary force for surfactant imbibition in the oil-wet cores.When the surfactant concentration was lower than the critical micelle concentration,the surfactant concentration was negatively correlated with the inverse Bond number and positively correlated with the oil recovery rate.When the surfactant concentration was higher than the critical micelle concentration,the oil recovery increased with a smaller interfacial tension.Nuclear magnetic resonance suggested that the movable pore and pore throat size in the oil-wet sample decreased from 0.363 mm in the untreated rock to 0.326 mm with the surfactant treatment,which indicated that the surfactant improved the flow capacity of the oil.The findings of this study can help to better understand the adsorption impact of surfactants on the characteristics of the oil/water and solid/liquid interfaces.The imbibition mechanism in oil-wet tight sandstone reservoirs was further revealed.These systematic approaches help to select appropriate surfactants for better recovery in oil-wet tight sandstone reservoirs through imbibition.
文摘In recent years,controlling the salinity and composition of the injected water has become an emerging enhanced oil recovery(EOR)technique,often described as low salinity(LS)waterflooding.This work is done with the intention to contribute to the ongoing discussions about LS waterflooding mechanism(s).For this purpose,a series of different experiments were conducted.At first,the effect of salinity on the interfacial tension(IFT)and the contact angle was evaluated with a crude oil sample.Then to achieve more accurate results in observing oil/water interface,similar IFT experiments were also carried out on a synthetic oil containing asphaltenes.Thereafter,microscopic visualization using glass micromodel was performed on the interface of the synthetic oil sample and brines.Four brine solutions including Sea Water(SW),it's dilutions and formation water(FW)were used for various experiments.Finally,to investigate the presented mechanism by other authors,a series of Environmental Scanning Electron Microscopy(ESEM)analysis on the synthetic oil was carried out to understand better the phase behaviour after contacting both synthetic oil and water phases from the micromodel experiment.Based on the existing mechanism,there exists an optimal concentration beyond which dilution is no longer an effective process.
基金the Faculty of Engineering University of Khartoum,Sudan,for the financial support of his studies at the University of Aberdeen
文摘Surfactant-based oil recovery processes are employed to lower the interfacial tension in immiscible displacement processes,change the wettability of rock to a more water-wet system and emulsify the oil to displace it in subsurface porous media.Furthermore,these phenomena can reduce the capillary pressure and enhance spontaneous imbibition.The key factors affecting such immiscible displacement process are temperature,salinity and p H of the fluids,surfactant concentration and adsorption.Therefore,before any surfactant flooding process is applied,extensive studies of fluid-fluid and rock-fluid interactions are needed.The use of other chemicals along with surfactants in chemical enhanced oil recovery(c EOR)processes have been widely considered to exploit the synergy of individual chemicals and complement the weakness arises from each of them during immiscible displacement of fluids in porous media.Therefore,such combinations of chemicals lead to alkaline-surfactant(AS),surfactantpolymer(SP),alkaline-surfactant-polymer(ASP),and nanoparticle-surfactant(NS)flooding processes,among others.In this review study,we categorised the role and displacement mechanisms of surfactants and discussed the key factors to be considered for analysing the fluid displacement in porous media.
文摘Nanofluids because of their surface characteristics improve the oil production from reservoirs by enabling different enhanced recovery mechanisms such as wettability alteration,interfacial tension(IFT)reduction,oil viscosity reduction,formation and stabilization of colloidal systems and the decrease in the asphaltene precipitation.To the best of the authors’ knowledge,the synthesis of a new nanocomposite has been studied in this paper for the first time.It consists of nanoparticles of both SiO2 and Fe3O4.Each nanoparticle has its individual surface property and has its distinct effect on the oil production of reservoirs.According to the previous studies,Fe3O4 has been used in the prevention or reduction of asphaltene precipitation and SiO2 has been considered for wettability alteration and/or reducing IFTs in enhanced oil recovery.According to the experimental results,the novel synthesized nanoparticles have increased the oil recovery by the synergistic effects of the formed particles markedly by activating the various mechanisms relative to the use of each of the nanoparticles in the micromodel individually.According to the results obtained for the use of this nanocomposite,understanding reservoir conditions plays an important role in the ultimate goal of enhancing oil recovery and the formation of stable emulsions plays an important role in oil recovery using this method.
基金the EOR Center at University Technology Petronas for providing financial support
文摘In this work, an experimental study combined with numerical simulation was conducted to investigate the potential of chemically enhanced water alternating gas (CWAG) injection as a new enhanced oil recovery method. The unique feature of this new method is that it uses alkaline, surfactant, and polymer additives as a chemical slug which is injected during the water alternating gas (WAG) process to reduce the interfacial tension (IFT) and simultaneously improve the mobility ratio. In essence, the proposed CWAG process involves a combination of chemical flooding and immiscible carbon dioxide (CO2) injection and helps in IFT reduction, water blocking reduction, mobility control, oil swelling, and oil viscosity reduction due to CO2 dissolution. Its performance was compared with the conventional immiscible water alter- nating gas (I-WAG) flooding. Oil recovery utilizing CWAG was better by 26 % of the remaining oil in place after waterflooding compared to the recovery using WAG conducted under similar conditions. The coreflood data (cumulative oil and water production) were history mat- ched via a commercial simulator by adjusting the relative permeability curves and assigning the values of the rock and fluid properties such as porosity, permeability, and the experimentally determined IFT data. History matching ofthe coreflood model helped us optimize the experiments and was useful in determining the importance of the parameters influencing sweep efficiency in the CWAG process. The effectiveness of the CWAG process in pro- viding enhancement of displacement efficiency is evident in the oil recovery and pressure response observed in the coreflood. The results of sensitivity analysis on CWAG slug patterns show that the alkaline-surfactant-polymer injection is more beneficial after CO2 slug injection due to oil swelling and viscosity reduction. The CO2 slug size analysis shows that there is an optimum CO2 slug size, around 25 % pore volume which leads to a maximum oil recovery in the CWAG process. This study shows that the ultralow IFT system, i.e., IFT equaling 10 2 or 10 3 mN/ m, is a very important parameter in CWAG process since the water blocking effect can be minimized.
基金Kuwait University General Research Facilities (GE01/17,GE01/07,and GS03/01)for their support in conducting the necessary experimental work of this study。
文摘This study investigated experimentally the coupled effects of hydrophilic SiO_(2) nanoparticles(NPs)and low-salinity water(LSW)on the wettability of synthetic clay-free Berea sandstone.Capillary pressure,interfacial tension(IFT),contact angle,Zeta potential,and dynamic displacement measurements were performed at various NP mass fractions and brine salinities.The U.S.Bureau of Mines(USBM)index was used to quantify the wettability alteration.Furthermore,the NP stability and retention and the effect of enhanced oil recovery by nanofluid were examined.The results showed that LSW immiscible displacement with NPs altered the wettability toward more water wet.With the decreasing brine salinity and increasing NP mass fraction,the IFT and contact angle decreased.The wettability alteration intensified most as the brine salinity decreased to 4000 mg/L and the NP mass fraction increased to 0.075%.Under these conditions,the resulting incremental oil recovery factor was approximately 13 percentage points.When the brine salinity was 4000 mg/L and the NP mass fraction was 0.025%,the retention of NPs caused the minimum damage to permeability.
文摘In order to improve oil recovery, Enhanced Oil Recovery (EOR) techniques have been applied to several light and medium oil reservoirs. This research was directed towards the development of chemical flooding methods for such reservoirs. The main objective of this experimental work was to investigate the efficiency of introducing various types of Ionic Liquids (ILs), 1-Ethyl-3-methylimidazolium Chloride [EMIM][Cl], 1-Benzyl-3-methylimidazolium Chloride [BenzMIM][Cl], and Trihexyltetradecylphosphonium Chloride [THTDPh][Cl] on the Recovery Factor (RF) of medium oil (Weyburn oil, 30.25 API°) at room temperature. The series of flooding experiments were carried out by introducing a slug of IL mixtures. Results demonstrated that maximum oil recovery factor was obtained when [EMIM][Cl] was added in the displacing fluid. Further investigations have been conducted to examine the effect of ILs concentrations on the recovery mechanisms by measuring Surface Tension (SFT), pH, and viscosity of the displacing phases. Finally, the effect of theses ILs in wettability alteration was examined.
基金supported by the National Key R&D Program of China(2018YFA0702400)National Natural Science Foundation of China(5207040347).
文摘A novel nanofluid of modified carbon black(MCB)nanoparticles was initially developed for enhanced oil recovery(EOR)in low permeability reservoirs.The MCB nanoparticles were obtained via a three-step reaction involving modification by oxidation,acyl chlorination,and activated grafting.MCB nano-particles were spherically dispersed,with an average size of 72.3 nm.Compared with carbon black(CB)nanoparticles,dispersed MCB nanoparticles can effectively reduce the oil-water interfacial tension(IFT)to 10^(-2)mN/m and change the surface wettability of sand particles.Based on the results of core flooding experiments,the MCB nanoparticles exhibited a better EOR capacity than surfactants and CB nano-particles,and the final oil recovery was significantly increased by 27.27%.The core scanning test showed that the MCB nanoparticles could plug high permeability channels by adsorbing onto the surfaces of sand particles and forming larger aggregates that bridge across pores or throats,resulting in a higher swept volume.The synergistic effects of improved swept volume and oil displacement efficiency were the EOR mechanisms of the MCB nanoparticles.The studies indicate that these MCB nanoparticles have excellent potential for EOR in low permeability reservoirs.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFB0308900)the National Natural Science Foundation of China (No. 51574125)+1 种基金the Fundamental Research Funds for the Central Universities of China (No. 50321101917017)provided by Research Program of State Key Laboratory of Bioreactor Engineering
文摘A new ultra-long chain monounsaturated 4-(N-nervonicamidopropyl-N,N-dimethylammonium)butane sulfonate(NDAS)zwitterionic surfactant with ultralow interfacial tensions was developed through the modification of nervonic acid derived from renewable non-edible seed oils by a simple and effective method.Its structure was characterized by ESI-HRMS,1 H NMR,and 13 C NMR.NDAS surfactant exhibited a strong interfacial activity(~10^(-4) mN/m)between the crude oil and the formation brine at a very low surfactant dosage(0.05 g/L)and at high salinity conditions,which is equivalent to 2%(w/w)of dosage of the most traditional surfactants used in the enhanced oil recovery field.Meanwhile,at a very low concentration(0.05 g/L),NDAS demonstrated strong NaCl compatibility up to 100 g/L,Ca^(2+)ions compatibility up to 200 mg/L,and temperature stability up to 90℃.The surface tension,emulsification,and biodegradability parameters were also evaluated.This work consolidates our hypothesis that increasing the hydrophobic chain length of a surfactant certainly contributes to the high interfacial activity and good compatibility of salts and temperatures.Hence,it will facilitate the design of a sustainable alternative to petroleum-based chemicals to develop bio-based surfactants and extend the domain of bio-based surfactants to new applications such as in enhanced oil recovery(EOR).
基金the Ministry of Science and Innovation and State Research Agency for financial support throughout project PGC2018-097342-B-I00, including European Regional Development Fund。
文摘The main advantages of the use of ionic liquids in enhanced oil recovery are their tunability and stability in harsh environmental conditions. In this work, a comprehensive review of ionic liquids proposed to improve current chemical oil recovery methods has been presented, focusing on core flooding experiments. With an almost infinite number of possible ionic liquids, the amount of experiments carried out up to now has been very limited. However, results are promising, with additional recovery after secondary flooding of up to 32% of the original oil in place. Most formulations with ionic liquids have been proposed for sandstone reservoirs, the number of studies with carbonate cores being very scarce. The possibilities of a new room temperature surface active ionic liquid, 1-decyl-3-methylimidazolium triflate,for this application were analyzed. It was shown that it is able to drastically reduce the water/oil interfacial tension. An optimized formulation was proposed for carbonate reservoirs. After secondary flooding with brine, an additional recovery of 10.5% of original oil in place was achieved at room conditions. A combination of the proposed method followed by a polymer flooding step with polyacrylamide led to a lesser but still significant recovery, reducing the costs associated to the ionic liquid.
文摘The switchable oil layer driven by electrowetting gives visible color and light valve control, which is the basis of Electro-Fluidic Displays. The colored oil’s property is a key factor that influences the Electro-Fluidic Displays switching behavior. A purple oil was formulated by the oil-soluble purple dye in decane in this study. The dye molecule itself is nonpolar and it doesn’t dissolve in water. The concentration of colored oil influenced the oil/water interfacial tension and oil viscosity. The relationship of EFD switching behavior with oil/water interfacial tension, oil viscosity, and oil conductivity has been systematically investigated. The oil/water interfacial tension decreased with increasing oil concentration, in the meanwhile, the conductivity increased. Oil conductivity was one of the key factors that influenced the Electro-Fluidic Displays optical property. We found for the first time that at the lower oil concentration (2% - 10%), the interfacial tension plays a main role effect on the rupture voltage and response time, but as the conductivity of higher concentration of colored oil increased (at 20%), the rupture voltage-controlled both by conductivity and interfacial tension.
文摘In chemical enhanced oil recovery, surfactants are injected into the reservoir with the intention to lower interfacial tension (IFT) between the water and oil phases, and thereby bring about efficient displacement of oil. However, the adsorption of the surfactants to reservoir rock surfaces leads to the loss and reduction in concentration of the surfactants, which in turn reduces the overall efficiency of the oil recovery process, with attendant financial losses. In this work, the adsorption of Quillaja Saponaria (QS), a novel, natural, non-ionic surfactant, on crushed sandstone reservoir rock is investigated. X-ray diffraction (XRD) study of clean sandstone particles has been undertaken to determine the main components present in the sand particles. The conductivity method was used to measure CMC and the surfactant concentrations in aqueous solutions. Batch adsorption experiments were used to determine the amount of QS adsorbed on rock surface. Equilibrium conditions were reached after almost 5 days. From the results of the study, the Langmuir isotherm model is more suited for predicting the adsorption behaviour of QS on sandstone. The kinetic adsorption of QS obeys the pseudo-second order model. This study is particularly relevant in surfactant selection for chemical EOR processes.