Polymer solutions are used in chemical EOR processes to achieve incremental oil recoveries through obtaining favorable mobility ratios. In the process, the?in-situ?viscosity is a key parameter for the polymer flood de...Polymer solutions are used in chemical EOR processes to achieve incremental oil recoveries through obtaining favorable mobility ratios. In the process, the?in-situ?viscosity is a key parameter for the polymer flood design, as well as the changes in permeability due to the retention or adsorption (e.g.: plugging). Understanding the major causes of the plugging effects allows?predicting injectivity problems as well as optimizing project design. The objective of this work is to use glass-silicon-glass micromodels in combination with tracer particles—attached to the flooded fluids—to qualitatively and quantitatively describe the extent of permeability changes?after polymer injection. Laboratory work is performed in order to determine the physical properties of the polymer solutions when they flow through porous media, such as the presence of permeability reduction/plugging of the micromodel. A statistical analysis of the distribution and extent of plugged areas?is performed and a study of the pressure response during various injection stages will complement the study. A biopolymer (Scleroglucan) was tested and compared to a commonly used polymer, giving a direct insight into their pros and cons. Five different concentrations of polymers were tested and put into relation with their quantitative and qualitative amount of sort of called retention. The amount of adsorption was determined?experimentally in one case in order to draw the significance. By exploiting the potential of GSG-micromodels in combination with tracer particles, it was possible to visualize the reduction of flow paths and its increase during various injections for the first time. Expanding the working principle proposed in this work could provide further understanding of the behavior of any polymers.?The results obtained and workflow presented in this work allow for additional understanding of polymer solutions behavior in flooding applications. Furthermore, the definition of optimized workflows to?assess any kind of solutions in porous media and permeability changes is?supported.展开更多
CQDs-doped TiO_(2)(C-TiO_(2))has drawn increased attention in recent because of its excellent catalytic performance.Understanding the transport of C-TiO_(2)in porous media is necessary for evaluating the environmental...CQDs-doped TiO_(2)(C-TiO_(2))has drawn increased attention in recent because of its excellent catalytic performance.Understanding the transport of C-TiO_(2)in porous media is necessary for evaluating the environmental process of this new nanomaterial.Column experiments were used in this study to investigate ionic strength(IS),dissolved organic matter(DOM)and sand grain size on the transport of C-TiO_(2).The mobility of C-TiO_(2)was inhibited by the increased IS and decreased sand grain size,but was promoted by the increased DOM concentration.The promotion efficiency of DOM ranked as humic acid(HA)>alginate(Alg)>bovine serum albumin(BSA),which was in the same order as their ability to change surface charges.The micromodels of pore network were prepared via 3D printing to further reveal the deposition mechanisms and spatial/temporal distribution of C-TiO_(2)in porous space.C-TiO_(2)mainly attached to the upstream region of collectors because of interception.The collector ripening was observed after long-time deposition.The existence of DOM caused visible decrease of C-TiO_(2)deposition in the pore network.HA caused the most remarkable reduce of deposition in the three types of DOM,which was consistent with the column experiment results.This research is helpful to predict the transport of C-TiO_(2)in natural porous media.展开更多
Colloidal transport and deposition in porous media are complex processes that result from the interaction between hydrodynamics(velocity,pore geometry,etc.)and Derjaguin-Landau-Verwey-Overbeek(DLVO)forces(particle-par...Colloidal transport and deposition in porous media are complex processes that result from the interaction between hydrodynamics(velocity,pore geometry,etc.)and Derjaguin-Landau-Verwey-Overbeek(DLVO)forces(particle-particle and particle-surface).They have important implications for engineering applications involving the reinjection of a fluidinto a medium,such as geothermal energy.The investigation of permeability stability is critical to ensure the sustainability of activities.This work aims to study the clogging mechanisms in a rock-like porous medium using a microfluidicdevice.The pore-throat network distributions reveal that the micromodel geometry mimics real rock samples.The transport of a monodispersed suspension is studied at different concentrations.Image analysis,velocity fieldmodeling,and pressure drop measurement are used to assess preferential clogging sites and porous medium permeability reduction,respectively.Experiments have shown that retention sites are located around preferential flow paths with relatively high flow velocities.When clogged,the pore thresholds are the deposition zones that lead to a reduction in permeability.However,pore bodies may also constitute deposition zones.Interestingly,as the concentration of the suspension increases,the kinetics of the permeability reduction are delayed,and the clogging mechanisms,as well as the type of deposit,evolve.Finally,at very high concentrations,the effects of hydrodynamic stripping are more important.These observations emphasize the role of the porous medium geometry in colloidal transport and deposition and thus permeability reduction.展开更多
This paper describes the results of microscopic study on fluid flows through porous media.The oil-water two-phase flow,the oil-air-water tri-phase flow.the Foam-surfactant-oil-water-air multi-phase flow,the microemuls...This paper describes the results of microscopic study on fluid flows through porous media.The oil-water two-phase flow,the oil-air-water tri-phase flow.the Foam-surfactant-oil-water-air multi-phase flow,the microemulsion-oil-water multi-phase flow and flow with neutralization reaction are introduced.The micromodels,the technology of fabricating micromodels and the method of their application are also described.展开更多
The applications of nanotechnology in oilfields have attracted the attention of researchers to nanofluid injection as a novel approach for enhanced oil recovery. To better understand the prevailing mechanisms in such ...The applications of nanotechnology in oilfields have attracted the attention of researchers to nanofluid injection as a novel approach for enhanced oil recovery. To better understand the prevailing mechanisms in such new displacement scenarios,micromodel experiments provide powerful tools to visually observe the way that nanoparticles may mobilize the trapped oil.In this work, the e ect of silicon oxide nanoparticles on the alteration of wettability of glass micromodels was investigated in both experimental and numerical simulation approaches. The displacement experiments were performed on the original water-wet and imposed oil-wet(after aging in stearic acid/n-heptane solution) glass micromodels. The results of injection of nanofluids into the oil-saturated micromodels were then compared with those of the water injection scenarios. The flooding scenarios in the micromodels were also simulated numerically with the computational fluid dynamics(CFD) method. A good agreement between the experimental and simulation results was observed. An increase of 9% and 13% in the oil recovery was obtained by nanofluid flooding in experimental tests and CFD calculations, respectively.展开更多
Due to the low porosity and low permeability in unconventional reservoirs,a large amount of crude oil is trapped in micro-to nano-sized pores and throats,which leads to low oil recovery.Nanofluids have great potential...Due to the low porosity and low permeability in unconventional reservoirs,a large amount of crude oil is trapped in micro-to nano-sized pores and throats,which leads to low oil recovery.Nanofluids have great potential to enhance oil recovery(EOR)in low permeability reservoirs.In this work,the regulating ability of a nanofluid at the oil/water/solid three-phase interface was explored.The results indicated that the nanofluid reduced the oil/water interfacial tension by two orders of magnitude,and the expansion modulus of oil/water interface was increased by 77% at equilibrium.In addition,the solid surface roughness was reduced by 50%,and the three-phase contact angle dropped from 135(oil-wet)to 48(water-wet).Combining the displacement experiments using a 2.5D reservoir micromodel and a microchannel model,the remaining oil mobilization and migration processes in micro-to nano-scale pores and throats were visualized.It was found that the nanofluid dispersed the remaining oil into small oil droplets and displaced them via multiple mechanisms in porous media.Moreover,the high strength interface film formed by the nanofluid inhibited the coalescence of oil droplets and improved the flowing ability.These results help to understand the EOR mechanisms of nanofluids in low permeability reservoirs from a visual perspective.展开更多
Recently,nanoparticles have been used along with surfactants for enhancing oil recovery.Although the recent studies show that oil recovery is enhanced using nanoparticle/surfactant solutions,some effective parameters ...Recently,nanoparticles have been used along with surfactants for enhancing oil recovery.Although the recent studies show that oil recovery is enhanced using nanoparticle/surfactant solutions,some effective parameters and mechanisms involved in the oil recovery have not yet been investigated.Therefore,the temperature effect on the stability of nanoparticle/surfactant solutions and ultimate oil recovery has been studied in this work,and the optimal concentrations of both SiO2 nanoparticle and surfactant(sodium dodecyl sulfate)have been determined by the Central Composite Design method.In addition,the simultaneous effects of parameters and their interactions have been investigated.Study of the stability of the injected solutions indicates that the nanoparticle concentration is the most important factor affecting the solution stability.The surfactant makes the solution more stable if used in appropriate concentrations below the CMC.According to the micromodel flooding results,the most effective factor for enhancing oil recovery is temperature compared to the nanoparticle and surfactant concentrations.Therefore,in floodings with higher porous medium temperature,the oil viscosity reduction is considerable,and more oil is recovered.In addition,the surfactant concentration plays a more effective role in reservoirs with higher temperatures.In other words,at a surfactant concentration of 250 ppm,the ultimate oil recovery is improved about 20%with a temperature increase of 20°C.However,when the surfactant concentration is equal to 750 ppm,the temperature increase enhances the ultimate oil recovery by only about 7%.Finally,the nanoparticle and surfactant optimum concentrations determined by Design-Expert software were equal to 46 and 159 ppm,respectively.It is worthy to note that obtained results are validated by the confirmation test.展开更多
Nanofluids and low-salinity water(LSW)flooding are two novel techniques for enhanced oil recovery.Despite some efforts on investigating benefits of each method,the pros and cons of their combined application need to b...Nanofluids and low-salinity water(LSW)flooding are two novel techniques for enhanced oil recovery.Despite some efforts on investigating benefits of each method,the pros and cons of their combined application need to be evaluated.This work sheds light on performance of LSW augmented with nanoparticles through examining wettability alteration and the amount of incremental oil recovery during the displacement process.To this end,nanofluids were prepared by dispersing silica nanoparticles(0.1 wt%,0.25 wt%,0.5 wt% and 0.75 wt%)in 2,10,20 and 100 times diluted samples of Persian Gulf seawater.Contact angle measurements revealed a crucial role of temperature,where no wettability alteration occurred up to 80 ℃.Also,an optimum wettability state(with contact angle 22°)was detected with a 20 times diluted sample of seawater augmented with 0.25 wt% silica nanoparticles.Also,extreme dilution(herein 100 times)will be of no significance.Throughout micromodel flooding,it was found that in an oil-wet condition,a combination of silica nanoparticles dispersed in 20 times diluted brine had the highest displacement efficiency compared to silica nanofluids prepared with deionized water.Finally,by comparing oil recoveries in both water-and oil-wet micromodels,it was concluded that nanoparticles could enhance applicability of LSW via strengthening wettability alteration toward a favorable state and improving the sweep efficiency.展开更多
By means of the pore-level simulation, the characteristics of gas-water flow and gas-water distribution during the alternative displacement of gas and water were observed directly from etched-glass micromodel. The res...By means of the pore-level simulation, the characteristics of gas-water flow and gas-water distribution during the alternative displacement of gas and water were observed directly from etched-glass micromodel. The results show that gas-water distribution styles are divided into continuous phase type and separate phase type. The water lock exists in pore and throat during the process of gas-water displacement, and it reduces the gas flow-rate and has some effects on the recovery efficiency during the operation of gas storage. According to the experimental results of aquifer gas storage in X area, the differences in available extent among reservoirs are significant, and the availability of pore space is 33% 45%.展开更多
The conservation of rheological and filtration properties of drilling fluids is essential during drilling operations.However,high-pressure and high-temperature conditions may affect drilling fluid additives,leading to...The conservation of rheological and filtration properties of drilling fluids is essential during drilling operations.However,high-pressure and high-temperature conditions may affect drilling fluid additives,leading to their degradation and reduced performance during operation.Hence,the main objective of this study is to formulate and evaluate a viscoelastic surfactant(VES)to design water-based drilling nanofluids(DNF).Silica nanomaterials are also incorporated into fluids to improve their main functional characteristics under harsh conditions.The investigation included:i)synthesis and characterization of VES through zeta potential,thermogravimetric analysis(TGA),Fourier transform infrared spectroscopy(FTIR),atomic force microscopy(AFM),and rheological behavior;ii)the effect of the presence of VES combined with silica nanoparticles on the rheological,filtration,thermal,and structural properties by steady and dynamic shear rheological,filter press,thermal aging assays,and SEM(SEM)assays,respectively;and iii)evaluation of filtration properties at the pore scale through a microfluidic approach.The rheological results showed that water-based muds(WBMs)in the presence of VES exhibited shearthinning and viscoelastic behavior slightly higher than that of WBMs with xanthan gum(XGD).Furthermore,the filtration and thermal properties of the drilling fluid improved in the presence of VES and silica nanoparticles at 0.1 wt%.Compared to the WBMs based on XGD,the 30-min filtrate volume for DNF was reduced by 75%.Moreover,the Herschel-Bulkley model was employed to represent the rheological behavior of fluids with an R2of approximately 0.99.According to SEM,laminar and spherical microstructures were observed for the WBMs based on VES and XGD,respectively.A uniform distribution of the nanoparticles was observed in the WBMs.The results obtained from microfluidic experiments indicated low dynamic filtration for fluids containing VES and silica nanoparticles.Specifically,the filtrate volume of fluids containing VES and VES with silica nanoparticles at 281 min was 0.35 and 0.04 m L,respectively.The differences in the rheological,filtration,thermal,and structural results were mainly associated with the morphological structure of VES or XGD and surface interactions with other WBMs additives.展开更多
Water injection remains the predominant method in the oil recovery process,but chemical flooding methods such as nanohybrid injection,with its distinct advantages,emerge as a promising alternative to traditional water...Water injection remains the predominant method in the oil recovery process,but chemical flooding methods such as nanohybrid injection,with its distinct advantages,emerge as a promising alternative to traditional water flooding(WF).This study employed a straightforward synthesizing method,specifically the sol-gel process,to graft polyacrylamide(PAM)onto Graphene Oxide(GO)and Carbon Nanotube(CNT).The objective was to combine the advantages of both polymer and nanoparticle flooding.Our investigation comprised a comprehensive series of static and displacement tests,aiming to investigate the impact of nanohybrid injection in comparison to conventional water and polymer flooding.A series of static tests,SEM,TEM,FTIR,as well as viscosity,IFT,contact angle,and stability assessments,were conducted.As dynamic tests,a series of injection tests were done using a glass micromodel with a high degree of heterogeneity containing both connected and disconnected fractures which makes injection fluid's work very hard to recover oil.Results of static tests such as bottle and TGA,showed that the synthesized nanohybrids have great stability against harsh conditions of the reservoir in case of formation water salinity and temperature conditions which differentiates our work from previous studies.By analyzing the results of dynamic tests it was found that reduction of Interfacial Tension or IFT(which is the forces acting at the interface of nanofluids and oil)showed the most effect on oil recovery as CNT/PAM nanohybrid were able to lower the IFT value the most compared to the other injection fluids and therefore exhibited the highest oil recovery factor Alongside IFT reduction mechanism,mobility control was found to be another important factor specially in case of recovering heavy oil when GO/PAM outperformed CNT/PAM's recovery factor as GO/PAM has more viscosity than CNT/PAM.展开更多
In low salinity polymer flooding(LSPF),an advanced hybrid method for enhanced oil recovery(EOR),less attention has been given to the impacts of potential determining ions on polymer behavior in carbonate reservoirs.Th...In low salinity polymer flooding(LSPF),an advanced hybrid method for enhanced oil recovery(EOR),less attention has been given to the impacts of potential determining ions on polymer behavior in carbonate reservoirs.Therefore,seawaters spiked with divalent ions were used with sulfonated polyacrylamide(SPAM)polymer to investigate the effects of potential determining ions on SPAM performance in wettability alteration,polymer adsorption,carbonate surface charge,viscosity enhancement,emulsion type,and oil recovery.Among divalent anions and cations,only excess amounts of Mg^(2+)in a smart water-polymer solution could alter the wettability from oil-wet to neutral-wet and make the rock/brine zeta potential positive.Additionally,higher SPAM adsorption onto carbonate surfaces was observed as Mg^(2+)concentration was doubled,driven by interactions between sulfonate groups(-SO_(3)^(-))and the positively charged rock surface.Conversely,excess SO_(4)^(2-)impeded interactions between -SO_(3)^(-) and positively charged carbonate rock species,reducing SPAM adsorption.At 5000 ppm SPAM concentration,excess divalent ions increased solution viscosity due to the shielding effect,with the highest viscosity achieved by doubling Mg^(2+)concentration.However,at 10,000 ppm SPAM concentration,only SO_(4)^(2-) improved viscosity,while Ca^(2+)and Mg^(2+)reduced the viscosity of smart water-polymer solutions.As for emulsions produced by smart water-polymer solutions,the presence of SPAM in smart water led to the production of water-in-oil(W/O)emulsions and increased the mean droplet size of water droplets due to the salt-out effect.According to the results obtained from calcite-coated micromodel flooding experi ments,the ultimate oil recovery for SW+SPAM(5000 ppm)was 34.2%.Also,a two-fold increase in the Mg^(2+)concentration rose the oil recovery by 6.5%.展开更多
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 ph...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.展开更多
Surfactant flooding is a well-known chemical approach for enhancing oil recovery.Surfactant flooding has the disadvantage that it cannot withstand the harsh reservoir conditions.Improvements in oil recovery and releas...Surfactant flooding is a well-known chemical approach for enhancing oil recovery.Surfactant flooding has the disadvantage that it cannot withstand the harsh reservoir conditions.Improvements in oil recovery and release are made possible by the use of nanoparticles and surfactants and CO_(2)co-injection because they generate stable foam,reduce the interfacial tension(IFT)between water and oil,cause emulsions to spontaneously form,change the wettability of porous media,and change the characteristics of flow.In the current work,the simultaneous injection of SiO_(2),Al2O3 nanoparticles,anionic surfactant SDS,and CO_(2)in various scenarios were evaluated to determine the microscopic and macroscopic efficacy of heavy oil recovery.IFT(interfacial tension)was reduced by 44%when the nanoparticles and SDS(2000 ppm)were added,compared to a reduction of roughly 57%with SDS only.SDS-stabilized CO_(2)foam flooding,however,is unstable due to the adsorption of SDS in the rock surfaces as well as in heavy oil.To assess foam's potential to shift CO_(2)from the high permeability zone(the thief zone)into the low permeability zone,directly visualizing micromodel flooding was successfully executed(upswept oil-rich zone).Based on typical reservoir permeability fluctuations,the permeability contrast(defined as the ratio of high permeability to low permeability)for the micromodel flooding was selected.However,the results of the experiment demonstrated that by utilizing SDS and nanoparticles,minimal IFT was reached.The addition of nanoparticles to surfactant solutions,however,greatly boosted oil recovery,according to the findings of flooding studies.The ultimate oil recovery was generally improved more by the anionic surfactant(SDS)solution including nanoparticles than by the anionic surfactant(SDS)alone.展开更多
High water-cut has become a worldwide challenge for oil production.It requires extensive efforts to process and dispose.This entails expanding water handling facilities and incurring high power consumption costs.Polym...High water-cut has become a worldwide challenge for oil production.It requires extensive efforts to process and dispose.This entails expanding water handling facilities and incurring high power consumption costs.Polymeric microsphere injection is a cost-effective way to deal with excessive water production from subterranean formations.This study reports a laboratory investigation on polymeric microsphere injection in a large volume to identify its in-depth fluid diversion capacity in a porous media with large pore/particle size ratio.The performance of polymeric microsphere injection was evaluated using etched glass micromodels based on the pore network of a natural carbonate rock,which were treated as water-wet or oil-wet micromodels.Waterflooding was conducted to displace oil at reservoir temperature of 95°C,followed by one pore volume of polymeric microsphere injection.Three polymeric microsphere samples with median particle size of 0.05,0.3,and 20μm were used to investigate the impact of particle size of the polymeric microspheres on incremental oil production capacity.Although the polymeric microspheres were much smaller than the pores,additional oil production was observed.The incremental oil production increased with increasing polymeric microsphere concentration and particle size.As a comparison,polymeric microsphere solutions were injected into oil-wet and water-wet micromodels after waterflooding.It was observed that the oil production in oil-wet micromodel was much higher than that in water-wet micromodel.The wettability of micromodels affected the distribution patterns of the remaining oil after waterflooding and further dominated the performance of the microsphere injection.The study supports the applicability of microsphere injection in oil-wet heterogeneous carbonates.展开更多
Increasing world request for energy has made oil extraction from reservoirs more desirable.Many novel EOR methods have been proposed and utilized for this purpose.Using nanocomposites in chemical flooding is one of th...Increasing world request for energy has made oil extraction from reservoirs more desirable.Many novel EOR methods have been proposed and utilized for this purpose.Using nanocomposites in chemical flooding is one of these novel methods.In this study,we investigated the impact of six injection solutions on the recovery of light and heavy oil with the presence of two different brines as formation water using a homogenous glass micromodel.All of the injection solutions were based on a 40,000 ppm Na Cl synthetic seawater(SSW),one of which was additive free and the others were prepared by dispersing nanocomposite silica-based polyacrylamide(NCSP),nanocomposite alumina-based polyacrylamide(NCAP),the combination of both nanocomposites silica and alumina based on polyacrylamide(NCSAP),surfactant(CTAB)and polyacrylamide(PAM)with a concentration of 1000 ppm as additives.The Stability of nanocomposites was tested against the salinity of the brine and temperature using salinity and DSC tests which were successful.Alongside stability tests,IFT,contact angle and oil recovery measurements were made.Visual results revealed that in addition to the effect of silica and alumina nanocomposite in reducing interfacial tension and wettability alteration,control of mobility ratio caused a major improvement in sweeping efficiency and oil recovery.According to the sweeping behavior of injected fluids,it was found that the main effect of surfactant was wettability alteration,for polyacrylamide was mobility control and for nanocomposites was the reduction of interfacial tension between oil and injected fluid,which was completely analyzed and checked out.Also,NCSAP with 95.83%and 70.33%and CTAB with 84.35%and 91%have the highest light oil recoveries at 250,000 ppm and 180,000 ppm salinity,respectively which is related to the superposition effect of interactions between nanocomposites,solution and oil.Based on our results it can be concluded that the most effective mechanism in oil recovery was IFT reduction which was done by CTAB reduction also by using a polymer-based nanocomposite such as NCSAP and adding the mobility control factor,the oil recovery can be further enhanced.In the case of heavy oil recovery,it can be concluded that the mobility control played a much more effective role when the PAM performed almost similarly to the CTAB and other nanocomposites with a recovery factor of around 17%.In this study,we tried to investigate the effect of different injection solutions and their related mechanisms on oil recovery.展开更多
The use of diethylenetriaminepentaacetic acid(DTPA)chelating agent has shown promising results for enhanced oil recovery(EOR)in prior research.Several mechanisms,mainly resulting from rock-fluid interaction,have been ...The use of diethylenetriaminepentaacetic acid(DTPA)chelating agent has shown promising results for enhanced oil recovery(EOR)in prior research.Several mechanisms,mainly resulting from rock-fluid interaction,have been proposed for chelating agent flooding;however,little attention has been paid to fluid-fluid interaction thus far.The assessment of these mechanisms has primarily relied on macroscopic techniques such as core flooding.This paper aims to investigate the injection of DTPA brine and its dominant mechanisms at the pore scale using a clay-coated micromodel.The micromodel tests were performed under oil-wet and water-wet states.For a more precise examination of fluid/fluid interactions,the dynamic interfacial tension(IFT)and Zeta potential were measured.It was observed that the injection of DTPA brine in water-wet state changed the saturation distribution and increased oil recovery.Based on visual inspections,this change in saturation distribution could potentially be linked to the formation of micro-dispersions and viscoelastic interfacial phenomena.Micro-dispersions facilitate flow to unswept areas,and viscoelastic interface formation reshapes the interface between oil and brine,causing disconnected oil droplets to coalesce and thus increase recovery.Under the oil-wet state,the micro-dispersion formation and wettability alteration can be the dominant mechanisms,and the amount of recovered oil was higher than that observed in the water-wet state.Furthermore,Zeta potential measurements at the interface between brine and oil showed a more negative value for DTPA brine,which is effective in wettability alteration and micro-dispersions stability.The results indicate that IFT reduction was not significant enough to be considered the dominant mechanism,although it assists in DTPA brine penetration into the crude oil and subsequent micro-dispersion formation.展开更多
This study was conducted to investigate the phenomenon of oil removal from inside pores using a self-designed microfluidic test kit.An artificial micromodel chip as a representation of porous rocks has been created wi...This study was conducted to investigate the phenomenon of oil removal from inside pores using a self-designed microfluidic test kit.An artificial micromodel chip as a representation of porous rocks has been created with a uniform pore structure design and made of PMMA(Polymethyl Methacrylate)material.The micromodel chip has a porosity of 27.8%as well as a permeability of 2.7 Darcy.By using the microfluidic test kit,this study has investigated how low salinity water(LSW)injection with MgCl_(2)divalent ions and the addition of anionic surfactant,linear alkylbenzene sulfonate mixed with nonionic surfactants,nonylphenol ethoxylate(NP-10)affects to oil recovery.The injection of LSW and surfactant solution was carried out with different injection stages,injection rates and surfactant solutions con-centrations.Visual images during the injection process are recorded for analysis,which is the advantage of dynamic testing using this microfluidic test kit over conventional coreflooding.From this study,it is indicated that the selection of ions contained in LSW affects the success of LSW injection.Reducing the surfactant injection rate from 50 mL/min to 20 mL/min can increase the oil recovery from 1.27%to 4.29%.Oil recovery was also higher on surfactant injection which resulted in lower interfacial tension of the system based on the calculation of interfacial tension obtained from the Chun-Huh and Ghosh equations from the Winsor test.From all injection scenarios carried out in this study,the highest increase in oil recovery of 26.87%OOIP was obtained by injecting surfactant solutions directly in the secondary stage without prior LSW injection.展开更多
文摘Polymer solutions are used in chemical EOR processes to achieve incremental oil recoveries through obtaining favorable mobility ratios. In the process, the?in-situ?viscosity is a key parameter for the polymer flood design, as well as the changes in permeability due to the retention or adsorption (e.g.: plugging). Understanding the major causes of the plugging effects allows?predicting injectivity problems as well as optimizing project design. The objective of this work is to use glass-silicon-glass micromodels in combination with tracer particles—attached to the flooded fluids—to qualitatively and quantitatively describe the extent of permeability changes?after polymer injection. Laboratory work is performed in order to determine the physical properties of the polymer solutions when they flow through porous media, such as the presence of permeability reduction/plugging of the micromodel. A statistical analysis of the distribution and extent of plugged areas?is performed and a study of the pressure response during various injection stages will complement the study. A biopolymer (Scleroglucan) was tested and compared to a commonly used polymer, giving a direct insight into their pros and cons. Five different concentrations of polymers were tested and put into relation with their quantitative and qualitative amount of sort of called retention. The amount of adsorption was determined?experimentally in one case in order to draw the significance. By exploiting the potential of GSG-micromodels in combination with tracer particles, it was possible to visualize the reduction of flow paths and its increase during various injections for the first time. Expanding the working principle proposed in this work could provide further understanding of the behavior of any polymers.?The results obtained and workflow presented in this work allow for additional understanding of polymer solutions behavior in flooding applications. Furthermore, the definition of optimized workflows to?assess any kind of solutions in porous media and permeability changes is?supported.
基金This work was supported by the National Natural Science Foundation of China(No.41773110)the National Natural Science Foundation of China-Shandong Joint Fund(No.U2006214)the Shenzhen Science and Technology Research and Development Funds,China(No.JCYJ20180301171357901).
文摘CQDs-doped TiO_(2)(C-TiO_(2))has drawn increased attention in recent because of its excellent catalytic performance.Understanding the transport of C-TiO_(2)in porous media is necessary for evaluating the environmental process of this new nanomaterial.Column experiments were used in this study to investigate ionic strength(IS),dissolved organic matter(DOM)and sand grain size on the transport of C-TiO_(2).The mobility of C-TiO_(2)was inhibited by the increased IS and decreased sand grain size,but was promoted by the increased DOM concentration.The promotion efficiency of DOM ranked as humic acid(HA)>alginate(Alg)>bovine serum albumin(BSA),which was in the same order as their ability to change surface charges.The micromodels of pore network were prepared via 3D printing to further reveal the deposition mechanisms and spatial/temporal distribution of C-TiO_(2)in porous space.C-TiO_(2)mainly attached to the upstream region of collectors because of interception.The collector ripening was observed after long-time deposition.The existence of DOM caused visible decrease of C-TiO_(2)deposition in the pore network.HA caused the most remarkable reduce of deposition in the three types of DOM,which was consistent with the column experiment results.This research is helpful to predict the transport of C-TiO_(2)in natural porous media.
文摘Colloidal transport and deposition in porous media are complex processes that result from the interaction between hydrodynamics(velocity,pore geometry,etc.)and Derjaguin-Landau-Verwey-Overbeek(DLVO)forces(particle-particle and particle-surface).They have important implications for engineering applications involving the reinjection of a fluidinto a medium,such as geothermal energy.The investigation of permeability stability is critical to ensure the sustainability of activities.This work aims to study the clogging mechanisms in a rock-like porous medium using a microfluidicdevice.The pore-throat network distributions reveal that the micromodel geometry mimics real rock samples.The transport of a monodispersed suspension is studied at different concentrations.Image analysis,velocity fieldmodeling,and pressure drop measurement are used to assess preferential clogging sites and porous medium permeability reduction,respectively.Experiments have shown that retention sites are located around preferential flow paths with relatively high flow velocities.When clogged,the pore thresholds are the deposition zones that lead to a reduction in permeability.However,pore bodies may also constitute deposition zones.Interestingly,as the concentration of the suspension increases,the kinetics of the permeability reduction are delayed,and the clogging mechanisms,as well as the type of deposit,evolve.Finally,at very high concentrations,the effects of hydrodynamic stripping are more important.These observations emphasize the role of the porous medium geometry in colloidal transport and deposition and thus permeability reduction.
文摘This paper describes the results of microscopic study on fluid flows through porous media.The oil-water two-phase flow,the oil-air-water tri-phase flow.the Foam-surfactant-oil-water-air multi-phase flow,the microemulsion-oil-water multi-phase flow and flow with neutralization reaction are introduced.The micromodels,the technology of fabricating micromodels and the method of their application are also described.
文摘The applications of nanotechnology in oilfields have attracted the attention of researchers to nanofluid injection as a novel approach for enhanced oil recovery. To better understand the prevailing mechanisms in such new displacement scenarios,micromodel experiments provide powerful tools to visually observe the way that nanoparticles may mobilize the trapped oil.In this work, the e ect of silicon oxide nanoparticles on the alteration of wettability of glass micromodels was investigated in both experimental and numerical simulation approaches. The displacement experiments were performed on the original water-wet and imposed oil-wet(after aging in stearic acid/n-heptane solution) glass micromodels. The results of injection of nanofluids into the oil-saturated micromodels were then compared with those of the water injection scenarios. The flooding scenarios in the micromodels were also simulated numerically with the computational fluid dynamics(CFD) method. A good agreement between the experimental and simulation results was observed. An increase of 9% and 13% in the oil recovery was obtained by nanofluid flooding in experimental tests and CFD calculations, respectively.
基金The authors sincerely appreciate the financial support from the National Natural Science Foundation of China(No.52074249,51874261)Fundamental Research Funds for the Central Universities(2-9-2019-103).
文摘Due to the low porosity and low permeability in unconventional reservoirs,a large amount of crude oil is trapped in micro-to nano-sized pores and throats,which leads to low oil recovery.Nanofluids have great potential to enhance oil recovery(EOR)in low permeability reservoirs.In this work,the regulating ability of a nanofluid at the oil/water/solid three-phase interface was explored.The results indicated that the nanofluid reduced the oil/water interfacial tension by two orders of magnitude,and the expansion modulus of oil/water interface was increased by 77% at equilibrium.In addition,the solid surface roughness was reduced by 50%,and the three-phase contact angle dropped from 135(oil-wet)to 48(water-wet).Combining the displacement experiments using a 2.5D reservoir micromodel and a microchannel model,the remaining oil mobilization and migration processes in micro-to nano-scale pores and throats were visualized.It was found that the nanofluid dispersed the remaining oil into small oil droplets and displaced them via multiple mechanisms in porous media.Moreover,the high strength interface film formed by the nanofluid inhibited the coalescence of oil droplets and improved the flowing ability.These results help to understand the EOR mechanisms of nanofluids in low permeability reservoirs from a visual perspective.
基金financially supported by the Iran Nanotechnology Initiative Council
文摘Recently,nanoparticles have been used along with surfactants for enhancing oil recovery.Although the recent studies show that oil recovery is enhanced using nanoparticle/surfactant solutions,some effective parameters and mechanisms involved in the oil recovery have not yet been investigated.Therefore,the temperature effect on the stability of nanoparticle/surfactant solutions and ultimate oil recovery has been studied in this work,and the optimal concentrations of both SiO2 nanoparticle and surfactant(sodium dodecyl sulfate)have been determined by the Central Composite Design method.In addition,the simultaneous effects of parameters and their interactions have been investigated.Study of the stability of the injected solutions indicates that the nanoparticle concentration is the most important factor affecting the solution stability.The surfactant makes the solution more stable if used in appropriate concentrations below the CMC.According to the micromodel flooding results,the most effective factor for enhancing oil recovery is temperature compared to the nanoparticle and surfactant concentrations.Therefore,in floodings with higher porous medium temperature,the oil viscosity reduction is considerable,and more oil is recovered.In addition,the surfactant concentration plays a more effective role in reservoirs with higher temperatures.In other words,at a surfactant concentration of 250 ppm,the ultimate oil recovery is improved about 20%with a temperature increase of 20°C.However,when the surfactant concentration is equal to 750 ppm,the temperature increase enhances the ultimate oil recovery by only about 7%.Finally,the nanoparticle and surfactant optimum concentrations determined by Design-Expert software were equal to 46 and 159 ppm,respectively.It is worthy to note that obtained results are validated by the confirmation test.
文摘Nanofluids and low-salinity water(LSW)flooding are two novel techniques for enhanced oil recovery.Despite some efforts on investigating benefits of each method,the pros and cons of their combined application need to be evaluated.This work sheds light on performance of LSW augmented with nanoparticles through examining wettability alteration and the amount of incremental oil recovery during the displacement process.To this end,nanofluids were prepared by dispersing silica nanoparticles(0.1 wt%,0.25 wt%,0.5 wt% and 0.75 wt%)in 2,10,20 and 100 times diluted samples of Persian Gulf seawater.Contact angle measurements revealed a crucial role of temperature,where no wettability alteration occurred up to 80 ℃.Also,an optimum wettability state(with contact angle 22°)was detected with a 20 times diluted sample of seawater augmented with 0.25 wt% silica nanoparticles.Also,extreme dilution(herein 100 times)will be of no significance.Throughout micromodel flooding,it was found that in an oil-wet condition,a combination of silica nanoparticles dispersed in 20 times diluted brine had the highest displacement efficiency compared to silica nanofluids prepared with deionized water.Finally,by comparing oil recoveries in both water-and oil-wet micromodels,it was concluded that nanoparticles could enhance applicability of LSW via strengthening wettability alteration toward a favorable state and improving the sweep efficiency.
基金Project(2011ZX05013-002)supported by National Science and Technology Major Projects of China
文摘By means of the pore-level simulation, the characteristics of gas-water flow and gas-water distribution during the alternative displacement of gas and water were observed directly from etched-glass micromodel. The results show that gas-water distribution styles are divided into continuous phase type and separate phase type. The water lock exists in pore and throat during the process of gas-water displacement, and it reduces the gas flow-rate and has some effects on the recovery efficiency during the operation of gas storage. According to the experimental results of aquifer gas storage in X area, the differences in available extent among reservoirs are significant, and the availability of pore space is 33% 45%.
基金funded by Fondo Francisco Jose de Caldas,MINCIENCIAS and Agencia Nacional de hidrocarburos(ANH)through contract No.112721-282-2023(Project 1118-1035-9300)with Universidad Nacional de Colombia-Sede Medellin and PAREX RESOURCES COLOMBIA AG SUCURSAL。
文摘The conservation of rheological and filtration properties of drilling fluids is essential during drilling operations.However,high-pressure and high-temperature conditions may affect drilling fluid additives,leading to their degradation and reduced performance during operation.Hence,the main objective of this study is to formulate and evaluate a viscoelastic surfactant(VES)to design water-based drilling nanofluids(DNF).Silica nanomaterials are also incorporated into fluids to improve their main functional characteristics under harsh conditions.The investigation included:i)synthesis and characterization of VES through zeta potential,thermogravimetric analysis(TGA),Fourier transform infrared spectroscopy(FTIR),atomic force microscopy(AFM),and rheological behavior;ii)the effect of the presence of VES combined with silica nanoparticles on the rheological,filtration,thermal,and structural properties by steady and dynamic shear rheological,filter press,thermal aging assays,and SEM(SEM)assays,respectively;and iii)evaluation of filtration properties at the pore scale through a microfluidic approach.The rheological results showed that water-based muds(WBMs)in the presence of VES exhibited shearthinning and viscoelastic behavior slightly higher than that of WBMs with xanthan gum(XGD).Furthermore,the filtration and thermal properties of the drilling fluid improved in the presence of VES and silica nanoparticles at 0.1 wt%.Compared to the WBMs based on XGD,the 30-min filtrate volume for DNF was reduced by 75%.Moreover,the Herschel-Bulkley model was employed to represent the rheological behavior of fluids with an R2of approximately 0.99.According to SEM,laminar and spherical microstructures were observed for the WBMs based on VES and XGD,respectively.A uniform distribution of the nanoparticles was observed in the WBMs.The results obtained from microfluidic experiments indicated low dynamic filtration for fluids containing VES and silica nanoparticles.Specifically,the filtrate volume of fluids containing VES and VES with silica nanoparticles at 281 min was 0.35 and 0.04 m L,respectively.The differences in the rheological,filtration,thermal,and structural results were mainly associated with the morphological structure of VES or XGD and surface interactions with other WBMs additives.
文摘Water injection remains the predominant method in the oil recovery process,but chemical flooding methods such as nanohybrid injection,with its distinct advantages,emerge as a promising alternative to traditional water flooding(WF).This study employed a straightforward synthesizing method,specifically the sol-gel process,to graft polyacrylamide(PAM)onto Graphene Oxide(GO)and Carbon Nanotube(CNT).The objective was to combine the advantages of both polymer and nanoparticle flooding.Our investigation comprised a comprehensive series of static and displacement tests,aiming to investigate the impact of nanohybrid injection in comparison to conventional water and polymer flooding.A series of static tests,SEM,TEM,FTIR,as well as viscosity,IFT,contact angle,and stability assessments,were conducted.As dynamic tests,a series of injection tests were done using a glass micromodel with a high degree of heterogeneity containing both connected and disconnected fractures which makes injection fluid's work very hard to recover oil.Results of static tests such as bottle and TGA,showed that the synthesized nanohybrids have great stability against harsh conditions of the reservoir in case of formation water salinity and temperature conditions which differentiates our work from previous studies.By analyzing the results of dynamic tests it was found that reduction of Interfacial Tension or IFT(which is the forces acting at the interface of nanofluids and oil)showed the most effect on oil recovery as CNT/PAM nanohybrid were able to lower the IFT value the most compared to the other injection fluids and therefore exhibited the highest oil recovery factor Alongside IFT reduction mechanism,mobility control was found to be another important factor specially in case of recovering heavy oil when GO/PAM outperformed CNT/PAM's recovery factor as GO/PAM has more viscosity than CNT/PAM.
文摘In low salinity polymer flooding(LSPF),an advanced hybrid method for enhanced oil recovery(EOR),less attention has been given to the impacts of potential determining ions on polymer behavior in carbonate reservoirs.Therefore,seawaters spiked with divalent ions were used with sulfonated polyacrylamide(SPAM)polymer to investigate the effects of potential determining ions on SPAM performance in wettability alteration,polymer adsorption,carbonate surface charge,viscosity enhancement,emulsion type,and oil recovery.Among divalent anions and cations,only excess amounts of Mg^(2+)in a smart water-polymer solution could alter the wettability from oil-wet to neutral-wet and make the rock/brine zeta potential positive.Additionally,higher SPAM adsorption onto carbonate surfaces was observed as Mg^(2+)concentration was doubled,driven by interactions between sulfonate groups(-SO_(3)^(-))and the positively charged rock surface.Conversely,excess SO_(4)^(2-)impeded interactions between -SO_(3)^(-) and positively charged carbonate rock species,reducing SPAM adsorption.At 5000 ppm SPAM concentration,excess divalent ions increased solution viscosity due to the shielding effect,with the highest viscosity achieved by doubling Mg^(2+)concentration.However,at 10,000 ppm SPAM concentration,only SO_(4)^(2-) improved viscosity,while Ca^(2+)and Mg^(2+)reduced the viscosity of smart water-polymer solutions.As for emulsions produced by smart water-polymer solutions,the presence of SPAM in smart water led to the production of water-in-oil(W/O)emulsions and increased the mean droplet size of water droplets due to the salt-out effect.According to the results obtained from calcite-coated micromodel flooding experi ments,the ultimate oil recovery for SW+SPAM(5000 ppm)was 34.2%.Also,a two-fold increase in the Mg^(2+)concentration rose the oil recovery by 6.5%.
基金the Petroleum Technology Research Center(PTRC)in Regina,Saskatchewan,Canadathe Natural Sciences and Engineering Research Council of Canada(NSERC)for their financial support of this work
文摘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.
基金The Petroleum Technology Research Centre (PTRC),MITACSgraduate studies at the University of Regina all provided funding for this study
文摘Surfactant flooding is a well-known chemical approach for enhancing oil recovery.Surfactant flooding has the disadvantage that it cannot withstand the harsh reservoir conditions.Improvements in oil recovery and release are made possible by the use of nanoparticles and surfactants and CO_(2)co-injection because they generate stable foam,reduce the interfacial tension(IFT)between water and oil,cause emulsions to spontaneously form,change the wettability of porous media,and change the characteristics of flow.In the current work,the simultaneous injection of SiO_(2),Al2O3 nanoparticles,anionic surfactant SDS,and CO_(2)in various scenarios were evaluated to determine the microscopic and macroscopic efficacy of heavy oil recovery.IFT(interfacial tension)was reduced by 44%when the nanoparticles and SDS(2000 ppm)were added,compared to a reduction of roughly 57%with SDS only.SDS-stabilized CO_(2)foam flooding,however,is unstable due to the adsorption of SDS in the rock surfaces as well as in heavy oil.To assess foam's potential to shift CO_(2)from the high permeability zone(the thief zone)into the low permeability zone,directly visualizing micromodel flooding was successfully executed(upswept oil-rich zone).Based on typical reservoir permeability fluctuations,the permeability contrast(defined as the ratio of high permeability to low permeability)for the micromodel flooding was selected.However,the results of the experiment demonstrated that by utilizing SDS and nanoparticles,minimal IFT was reached.The addition of nanoparticles to surfactant solutions,however,greatly boosted oil recovery,according to the findings of flooding studies.The ultimate oil recovery was generally improved more by the anionic surfactant(SDS)solution including nanoparticles than by the anionic surfactant(SDS)alone.
文摘High water-cut has become a worldwide challenge for oil production.It requires extensive efforts to process and dispose.This entails expanding water handling facilities and incurring high power consumption costs.Polymeric microsphere injection is a cost-effective way to deal with excessive water production from subterranean formations.This study reports a laboratory investigation on polymeric microsphere injection in a large volume to identify its in-depth fluid diversion capacity in a porous media with large pore/particle size ratio.The performance of polymeric microsphere injection was evaluated using etched glass micromodels based on the pore network of a natural carbonate rock,which were treated as water-wet or oil-wet micromodels.Waterflooding was conducted to displace oil at reservoir temperature of 95°C,followed by one pore volume of polymeric microsphere injection.Three polymeric microsphere samples with median particle size of 0.05,0.3,and 20μm were used to investigate the impact of particle size of the polymeric microspheres on incremental oil production capacity.Although the polymeric microspheres were much smaller than the pores,additional oil production was observed.The incremental oil production increased with increasing polymeric microsphere concentration and particle size.As a comparison,polymeric microsphere solutions were injected into oil-wet and water-wet micromodels after waterflooding.It was observed that the oil production in oil-wet micromodel was much higher than that in water-wet micromodel.The wettability of micromodels affected the distribution patterns of the remaining oil after waterflooding and further dominated the performance of the microsphere injection.The study supports the applicability of microsphere injection in oil-wet heterogeneous carbonates.
文摘Increasing world request for energy has made oil extraction from reservoirs more desirable.Many novel EOR methods have been proposed and utilized for this purpose.Using nanocomposites in chemical flooding is one of these novel methods.In this study,we investigated the impact of six injection solutions on the recovery of light and heavy oil with the presence of two different brines as formation water using a homogenous glass micromodel.All of the injection solutions were based on a 40,000 ppm Na Cl synthetic seawater(SSW),one of which was additive free and the others were prepared by dispersing nanocomposite silica-based polyacrylamide(NCSP),nanocomposite alumina-based polyacrylamide(NCAP),the combination of both nanocomposites silica and alumina based on polyacrylamide(NCSAP),surfactant(CTAB)and polyacrylamide(PAM)with a concentration of 1000 ppm as additives.The Stability of nanocomposites was tested against the salinity of the brine and temperature using salinity and DSC tests which were successful.Alongside stability tests,IFT,contact angle and oil recovery measurements were made.Visual results revealed that in addition to the effect of silica and alumina nanocomposite in reducing interfacial tension and wettability alteration,control of mobility ratio caused a major improvement in sweeping efficiency and oil recovery.According to the sweeping behavior of injected fluids,it was found that the main effect of surfactant was wettability alteration,for polyacrylamide was mobility control and for nanocomposites was the reduction of interfacial tension between oil and injected fluid,which was completely analyzed and checked out.Also,NCSAP with 95.83%and 70.33%and CTAB with 84.35%and 91%have the highest light oil recoveries at 250,000 ppm and 180,000 ppm salinity,respectively which is related to the superposition effect of interactions between nanocomposites,solution and oil.Based on our results it can be concluded that the most effective mechanism in oil recovery was IFT reduction which was done by CTAB reduction also by using a polymer-based nanocomposite such as NCSAP and adding the mobility control factor,the oil recovery can be further enhanced.In the case of heavy oil recovery,it can be concluded that the mobility control played a much more effective role when the PAM performed almost similarly to the CTAB and other nanocomposites with a recovery factor of around 17%.In this study,we tried to investigate the effect of different injection solutions and their related mechanisms on oil recovery.
文摘The use of diethylenetriaminepentaacetic acid(DTPA)chelating agent has shown promising results for enhanced oil recovery(EOR)in prior research.Several mechanisms,mainly resulting from rock-fluid interaction,have been proposed for chelating agent flooding;however,little attention has been paid to fluid-fluid interaction thus far.The assessment of these mechanisms has primarily relied on macroscopic techniques such as core flooding.This paper aims to investigate the injection of DTPA brine and its dominant mechanisms at the pore scale using a clay-coated micromodel.The micromodel tests were performed under oil-wet and water-wet states.For a more precise examination of fluid/fluid interactions,the dynamic interfacial tension(IFT)and Zeta potential were measured.It was observed that the injection of DTPA brine in water-wet state changed the saturation distribution and increased oil recovery.Based on visual inspections,this change in saturation distribution could potentially be linked to the formation of micro-dispersions and viscoelastic interfacial phenomena.Micro-dispersions facilitate flow to unswept areas,and viscoelastic interface formation reshapes the interface between oil and brine,causing disconnected oil droplets to coalesce and thus increase recovery.Under the oil-wet state,the micro-dispersion formation and wettability alteration can be the dominant mechanisms,and the amount of recovered oil was higher than that observed in the water-wet state.Furthermore,Zeta potential measurements at the interface between brine and oil showed a more negative value for DTPA brine,which is effective in wettability alteration and micro-dispersions stability.The results indicate that IFT reduction was not significant enough to be considered the dominant mechanism,although it assists in DTPA brine penetration into the crude oil and subsequent micro-dispersion formation.
文摘This study was conducted to investigate the phenomenon of oil removal from inside pores using a self-designed microfluidic test kit.An artificial micromodel chip as a representation of porous rocks has been created with a uniform pore structure design and made of PMMA(Polymethyl Methacrylate)material.The micromodel chip has a porosity of 27.8%as well as a permeability of 2.7 Darcy.By using the microfluidic test kit,this study has investigated how low salinity water(LSW)injection with MgCl_(2)divalent ions and the addition of anionic surfactant,linear alkylbenzene sulfonate mixed with nonionic surfactants,nonylphenol ethoxylate(NP-10)affects to oil recovery.The injection of LSW and surfactant solution was carried out with different injection stages,injection rates and surfactant solutions con-centrations.Visual images during the injection process are recorded for analysis,which is the advantage of dynamic testing using this microfluidic test kit over conventional coreflooding.From this study,it is indicated that the selection of ions contained in LSW affects the success of LSW injection.Reducing the surfactant injection rate from 50 mL/min to 20 mL/min can increase the oil recovery from 1.27%to 4.29%.Oil recovery was also higher on surfactant injection which resulted in lower interfacial tension of the system based on the calculation of interfacial tension obtained from the Chun-Huh and Ghosh equations from the Winsor test.From all injection scenarios carried out in this study,the highest increase in oil recovery of 26.87%OOIP was obtained by injecting surfactant solutions directly in the secondary stage without prior LSW injection.
