A pseudo-three-dimensional model of potentiality prediction is proposed for enhanced oil recovery, based on the streamline method described in this article. The potential distribution of the flow through a porous medi...A pseudo-three-dimensional model of potentiality prediction is proposed for enhanced oil recovery, based on the streamline method described in this article. The potential distribution of the flow through a porous medium under a complicated boundary condition is solved with the boundary element method. Furthermore, the method for tracing streamlines between injection wells and producing wells is presented. Based on the results, a numerical solution can be obtained by solving the seepage problem of the stream-tube with consideration of different methods of Enhanced Oil Recovery（EOR）. The advantage of the method given in this article is that it can obtain dynamic calculation with different well patterns of any shape by easily considering different physicochemical phenomena having less calculation time and good stability. Based on the uniform theory basis-streamline method, different models, including CO2 miscible flooding, polymer flooding, alkaline/surfactant/polymer flooding and microbial flooding, are established in this article.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
Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid proper...Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.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
The development of fractured-vuggy carbonate reservoirs is extremely difficult because of the complex fractured-vuggy structure and strong heterogeneity.Foam flooding is a potential enhanced oil recovery(EOR)technolog...The development of fractured-vuggy carbonate reservoirs is extremely difficult because of the complex fractured-vuggy structure and strong heterogeneity.Foam flooding is a potential enhanced oil recovery(EOR)technology in fractured-vuggy carbonate reservoirs.Based on the similarity criterion,three types of 2D visual physical models of the fractured-vuggy structure were made by laser ablation technique,and a 3D visual physical model of the fractured-vuggy reservoir was made by 3D printing technology.Then the physical analog experiments of foam flooding were carried out in these models.The experimental results show that foam can effectively improve the mobility ratio,control the flow velocity of the fluid in different directions,and sweep complex fracture networks.The effect of foam flooding in fractures can be improved by increasing foam strength and enhancing foam stability.The effect of foam flooding in vugs can be improved by reducing the density of the foam and the interfacial tension between foam and oil.Three types of microscopic residual oil and three types of macroscopic residual oil can be displaced by foam flooding.This study verifies the EOR of foam flooding in the fractured-vuggy reservoir and provides theoretical support for the application of foam flooding in fractured-vuggy reservoirs.展开更多
Steam flooding with the assistance of carbon dioxide (CO_(2)) and chemicals is an effective approach for enhancing super heavy oil recovery. However, the promotion and application of CO_(2) and chemical agent-assisted...Steam flooding with the assistance of carbon dioxide (CO_(2)) and chemicals is an effective approach for enhancing super heavy oil recovery. However, the promotion and application of CO_(2) and chemical agent-assisted steam flooding technology have been restricted by the current lack of research on the synergistic effect of CO_(2) and chemical agents on enhanced steam flooding heat transfer. The novel experiments on CO_(2)–chemicals cooperate affected steam condensation and seepage were conducted by adding CO_(2) and two chemicals (sodium dodecyl sulfate (SDS) and the betaine temperature-salt resistant foaming agent ZK-05200).According to the experimental findings, a “film” formed on the heat-transfer medium surface following the co-injection of CO_(2) and the chemical to impede the steam heat transfer, reducing the heat transfer efficiency of steam, heat flux and condensation heat transfer coefficient. The steam seepage experiment revealed that the temperature at the back end of the sandpack model was dramatically raised by 3.5–12.8 °C by adding CO_(2) and chemical agents, achieving the goal of driving deep-formation heavy oil. The combined effect of CO_(2) and SDS was the most effective for improving steam heat transfer, the steam heat loss was reduced by 6.2%, the steam condensation cycle was prolonged by 1.3 times, the condensation heat transfer coefficient was decreased by 15.5%, and the heavy oil recovery was enhanced by 9.82%. Theoretical recommendations are offered in this study for improving the CO_(2)–chemical-assisted steam flooding technique.展开更多
The presence of a bottom water(BW)layer in heavy oil reservoirs can present substantial problems for efficient oil recovery for all recovery techniques.Hence,it is necessary to know how particular production processes...The presence of a bottom water(BW)layer in heavy oil reservoirs can present substantial problems for efficient oil recovery for all recovery techniques.Hence,it is necessary to know how particular production processes are affected by different BW layer thicknesses,and how standard production procedures can be adapted to handle such reservoirs.Toe-to-heel air injection(THAI)is a thermally efficient process,generating in situ energy in the reservoir by burning a fraction of the oil-in-place as coke and has the potential to economically and environmentally friendly work in reservoirs with BW layer.However,to ascertain that,studies are needed first.These are conducted via numerical simulations using commercial reservoir thermal simulator,CMG STARS.This work has shown that the shape of the combustion zone in THAI remains forward-leaning even in the presence of a BW layer,indicating that the process is stable,and that there is no oxygen bypassing of the combustion front.However,the oil recovery rate is highly negatively affected by how large the thickness of the BWzone is,and the severity of such effect is determined to be proportional to the thickness of the BW layer.This study also shows that there is a period of low oil production rate which corresponds to mobilised oil displacement into the BW zone which in turn causes a surge in water production rate.The practical implication of this is that prolonged period of low oil production rates will expose companies and/or investors to higher risk due to the oil market volatility.In this study,it is also revealed that the height of the mobilised oil that is displaced into the BW zone equates to that of the displaced and replaced water thereby implying that when the BW layer thickness is 50%that of the oil layer(OL),less than 50%of the mobilised oil will be recovered when the entire reservoir is swept by the combustion front.Therefore,conclusively,applying the THAI process in its conventional form in reservoirs containing bottom water is not recommended,and as a result,a ne展开更多
Solvents are generally used to reduce the viscosity of heavy crude oil and ultimately enhance oil recovery.Recently,a new method has been introduced where nanoparticles(NPs)are exploited to induce enhanced oil recover...Solvents are generally used to reduce the viscosity of heavy crude oil and ultimately enhance oil recovery.Recently,a new method has been introduced where nanoparticles(NPs)are exploited to induce enhanced oil recovery owing to their ability to improve the mobility ratio,dampen the interfacial tension,and alter rock wett-ability.This study investigated the integration of nano-alumina(Al_(2)O_(3))NPs with an n-hexane solvent.In parti-cular,a Brookfield viscometer has been used to measure the crude oil viscosity and it has been found that NPs can effectively lead to a significant decrease in the overall oil viscosity(70 cp using the solvent only,45 cp when NPs are added).展开更多
The study of flow through porous media has been of cardinal gravity in oil and gas applications like enhanced oil recovery(EOR),acidizing,fracturing,etc.One of the most anticipated apprehensions is that the core flood...The study of flow through porous media has been of cardinal gravity in oil and gas applications like enhanced oil recovery(EOR),acidizing,fracturing,etc.One of the most anticipated apprehensions is that the core flooding and simulation have become prevalent to understand the flow through porous media.This study aims at simulating and analyzing the effect of alkaline surfactant flooding through heterogeneous permeability conditions in the lab-scale methods.The conventional methods of core flood deal with the effective permeability of the system without considering the effect of heterogeneity within the core.The heterogeneous studies are conducted by simulating a finely meshed 2-D axisymmetric model of the sand pack.The novel Karanj oil surfactant extracted from Pongamia Pinnata,and partially hydrolyzed polyacryl amide polymer are considered for the physicochemical properties of displacing fluid used in the simulations.Different heterogeneity combinations and displacing fluid injection flow rates are introduced for a single absolute permeability system.Results indicate a trend of oil recovery upright with increasing vertical permeability.A lower areal sweep efficiency and early breakthrough are observed in models with high horizontal permeabilities.Further,the effect of heterogeneity on oil recovery is reduced with the increase in injection flow rates of displacing fluid.The present work utilizes computational fluid dynamics to model multiphase flow through a heterogeneous permeability media and its effect on oil recovery.展开更多
A novel concept of treating oil reservoirs by nanofluids is being developed to improve oil recovery and reduce the trapped oil in hydrocarbon reservoirs.Nanoparticles show great potential in enhancing oil recovery und...A novel concept of treating oil reservoirs by nanofluids is being developed to improve oil recovery and reduce the trapped oil in hydrocarbon reservoirs.Nanoparticles show great potential in enhancing oil recovery under ambient conditions.In this paper,the approaches of wettability alteration by using nanofluid,stability of nanofluids,and the most reliable wettability alteration mechanisms associated with variant types of nanoparticles have been reviewed.Moreover,the parameters that have a significant influence on nanofluid flooding have been discussed.Finally,the recent studies of the effect of nanoparticles on wettability alteration have been summarised and analysed.Furthermore,this paper presents possible opportunities and challenges regarding wettability alteration using nanofluids.展开更多
Carbon dioxide(CO2) flooding is one of the most globally used EOR processes to enhance oil recovery.However,the low gas viscosity and density result in gas channeling and gravity override which lead to poor sweep effi...Carbon dioxide(CO2) flooding is one of the most globally used EOR processes to enhance oil recovery.However,the low gas viscosity and density result in gas channeling and gravity override which lead to poor sweep efficiency.Foam application for mobility control is a promising technology to increase the gas viscosity,lower the mobility and improve the sweep efficiency in the reservoir.Foam is generated in the reservoir by co-injection of surfactant solutions and gas.Although there are many surfactants that can be used for such purpose,their performance with supercritical CO2(ScCO2) is weak causing poor or loss of mobility control.This experimental study evaluates a newly developed surfactant(CNF) that was introduced for ScCO2 mobility control in comparison with a common foaming agent,anionic alpha olefin sulfonate(AOS) surfactant.Experimental work was divided into three stages:foam static tests,interfacial tension measurements,and foam dynamic tests.Both surfactants were investigated at different conditions.In general,results show that both surfactants are good foaming agents to reduce the mobility of ScCO2 with better performance of CNF surfactant.Shaking tests in the presence of crude oil show that the foam life for CNF extends to more than 24 h but less than that for AOS.Moreover,CNF features lower critical micelle concentration(CMC),higher adsorption,and smaller area/molecule at the liquid-air interface.Furthermore,entering,spreading,and bridging coefficients indicate that CNF surfactant produces very stable foam with light crude oil in both deionized and saline water,whereas AOS was stable only in deionized water.At all conditions for mobility reduction evaluation,CNF exhibits stronger flow resistance,higher foam viscosity,and higher mobility reduction factor than that of AOS surfactant.In addition,CNF and ScCO2 simultaneous injection produced 8.83% higher oil recovery than that of the baseline experiment and 7.87% higher than that of AOS.Pressure drop profiles for foam flooding using CNF was slightly higher 展开更多
Injecting CO2into hydrocarbon reservoirs can enhance the recovery of hydrocarbon resources,and simultaneously,CO2can be stored in the rese rvoirs,reducing considerable amount of carbon emissions in the atmosphere.Howe...Injecting CO2into hydrocarbon reservoirs can enhance the recovery of hydrocarbon resources,and simultaneously,CO2can be stored in the rese rvoirs,reducing considerable amount of carbon emissions in the atmosphere.However,injected CO_(2)tends to go through fractures,high-permeability channels and streaks present in reservoirs,resulting in inefficient hydrocarbon recovery coupled with low CO_(2)storage performance.Conformance treatments with CO_(2)-resistant crosslinked polymer gels were performed in this study to mitigate the CO_(2)channeling issue and promote the synergy between enhanced oil recovery(EOR) and subsurface sequestration of CO_(2).Based on a typical low-permeability CO_(2)-flooding reservoir in China,studies were performed to investigate the EOR and CO_(2)storage performance with and without conformance treatment.The effect of permeability contrast between the channels and rese rvoir matrices,treatment size,and plugging strength on the efficiency of oil recovery and CO_(2)storage was systematically investigated.The results indicated that after conformance treatments,the CO_(2)channeling problem was mitigated during CO_(2)flooding and storage.The injected CO_(2)was more effectively utilized to recover the hydrocarbons,and entered wider spectrum of pore spaces.Consequently,more CO_(2)was trapped underground.Pronounced factors on the synergy of EOR and CO_(2)storage were figured out.Compared with the treatment size,the CO_(2)storage efficiency was more sensitive to the plugging strength of the conformance treatment materials.This observation was important for conformance treatment design in CCUS-EOR projects.According to this study,the materials should reduce the channel permeability to make the channel/matrix permeability ratio below 30.The results demonstrate the importance of conformance treatment in maximizing the performance of CCUS-EOR process to achieve both oil recovery improvement and efficient carbon storage.This study provides guidelines for successful field applications of CO_(2)transport co展开更多
Applying chemical flooding in petroleum reservoirs turns into interesting subject of the recent researches.Developing strategies of the aforementioned method are more robust and precise when they consider both economi...Applying chemical flooding in petroleum reservoirs turns into interesting subject of the recent researches.Developing strategies of the aforementioned method are more robust and precise when they consider both economical point of views(net present value(NPV))and technical point of views(recovery factor(RF)).In the present study huge attempts are made to propose predictive model for specifying efficiency of chemical flooding in oil reservoirs.To gain this goal,the new type of support vector machine method which evolved by Suykens and Vandewalle was employed.Also,high precise chemical flooding data banks reported in previous works were employed to test and validate the proposed vector machine model.According to the mean square error(MSE),correlation coefficient and average absolute relative deviation,the suggested LSSVM model has acceptable reliability;integrity and robustness.Thus,the proposed intelligent based model can be considered as an alternative model to monitor the efficiency of chemical flooding in oil reservoir when the required experimental data are not available or accessible.展开更多
The Surface engineering of nanoparticles has contributed to the development of nanoscience and nanotechnology by designing of new material depends on their surface modifier with series of functional properties and app...The Surface engineering of nanoparticles has contributed to the development of nanoscience and nanotechnology by designing of new material depends on their surface modifier with series of functional properties and applications.The dispersed nanoparticles can change or modify the interfacial properties in liquid-liquid system in aqueous phase if their surface is modified by ionic surfactant.The interfacial energy in nanoparticles-brine system,the ions tends to modify the transport phenomena in pore channels and improve the recovery.The use of the suspension of the particles at nanoscales can offer some advantages of induced sedimentation stability by surface force easily counter balance the force of gravity.This happened due to their nanosize,nanostructure,high volume to surface ratio and strong rock fluid interaction.It also influences the emulsion stability and alters the surface characteristics of surfactant and polymer within the rock in porous medium.Some of the problems associated with conventional EOR processes have been solved by nanoscience applications due to their potential response to reduce the interfacial tension at low to ultra-low level,wettability reversal and improvement in rheology of formation fluids.The large specific surface area,high reactivity,toughness and other properties of Nanoparticles can immensely improve the oil mobility compare to conventional EOR.This paper updates the latest review,experimental evidences and re-interpretation of past research data and applications in respect of silica and titanium dioxide nanoparticles in different environment within surfactant(s),polymer(s),polymer-surfactant EOR processes.The nanotechnology therefore is an effective and alternate solution to brush up the traditional EOR approach with state of art technology which can revolutionize the total oil and gas industry and can contributes significantly to enhance the economics of oil field industry.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
Based on the analysis of recent projections by the International Energy Agency(IEA),to meet the growing and subsequently declining demands of oil from now to 2040,we need up to around 770 billion barrels of oil.Since ...Based on the analysis of recent projections by the International Energy Agency(IEA),to meet the growing and subsequently declining demands of oil from now to 2040,we need up to around 770 billion barrels of oil.Since the worldwide total proved reserves of easy-and-cheaper-to-produce conventional oils is roughly only 520.2 billion barrels,the remaining 249.8 billion barrels must be obtained from unconventional petroleum resources(i.e.heavy oils and bitumen).These resources are however very difficult and costly to upgrade and produce due to their inherently high asphaltene contents which are reflected in their very high viscosities and large densities.However,still they should prove attractive development prospects if,as much as practicably possible,their upgrading can be performed in conjunction with in situ or downhole catalytic upgrading processes.Such projects will contribute significantly towards smoother and greener transition to full decarbonisation.Advanced technologies,such as the toe-to-heel air injection coupled to its add-on in situ catalytic process(i.e.THAI-CAPRI processes),have the potential to develop these reserves,but require further developmental understanding to realise their full capability.In this work,a new detailed procedure for numerically simulating the THAI-CAPRI processes is presented.The numerical model is made-up of Athabasca-type bitumen and it has a horizontal producer(HP)well that is surrounded by an annular layer of alumina-supported cobalt-oxide-molybdenum-oxide(CoMo/γ-Al2O3)catalyst.The simulation is performed using the computer modelling group(CMG)reservoir simulator,STARS.This new work has shown that the choice of the frequency factor of the catalytic reactions allowed model validation based on the degree of catalytic upgrading in form of API gravity.Overall,the work herein identifies the important parameters,such as API gravity,peak temperature,oil production rate,cumulative oil production,produced oxygen concentration,temperature distribution profile,extent of coke depositio展开更多
According to the analysis of the 2020 estimates of the International Energy Agency(2020),the world will require up to 770 billion barrels of oil from now to 2040.However,based on the British Petroleum(BP)statistical r...According to the analysis of the 2020 estimates of the International Energy Agency(2020),the world will require up to 770 billion barrels of oil from now to 2040.However,based on the British Petroleum(BP)statistical review of world energy 2020,the world-wide total reserve of the conventional light oil is only 520.2 billion barrels as at the end of 2019.That implies that the remaining 249.8 billion barrels of oil urgently needed to ensure a smooth transition to a decarbonised global energy and economic systems is provided must come from unconventional oils(i.e.heavy oils and bitumen)reserves.But heavy oils and bitumen are very difficult to produce and the current commercial production technologies have poor efficiency and release large quantities of greenhouse gases.Therefore,these resources should ideally be upgraded and produced using technologies that have greener credentials.This is where the energy-efficient,environmentally friendly,and self-sustaining THAI-CAPRI coupled in situ combustion and in situ catalytic upgrading process comes in.However,the novel THAI-CAPRI process is trialled only once at field and it has not gained wide recognition due to poor understanding of the optimal design parameters and procedures.Hence,this work reports the first ever results of investigations of the effect of operating pressure on the performance of the THAI-CAPRI process.Two experimental scale numerical models of the process based on Athabasca tar sand properties were run at pressures of 8000 kPa and 500 kPa respectively using CMG STARS.This study has shown that the higher the operating pressure,the larger the API gravity and the higher the cumulative volume of high-quality oil is produced(i.e.a 2300 cm3 of z24 oAPI oil produced at 8000 kPa versus the 2050 cm3 of z17.5 oAPI oil produced at 500 kPa).The study has further shown that despite presence of annular catalyst layer,the THAI-CAPRI process operates stably.However,it is found that a more stable and safer operation of the process can only be achieved at optimal pressu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
This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions(high salinity,high divalent ion concentration,high temperature,light oil,and hydrocarbon injection gas)in a sandston...This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions(high salinity,high divalent ion concentration,high temperature,light oil,and hydrocarbon injection gas)in a sandstone reservoir.For this,we selected anionic Alpha Olefin Sulfonate(AOS)surfactants and studied their synergistic effects in mixtures with zwitterionic betaines to enhance foam performance.The laboratory workflow used to define the best formulation followed a de-risking approach in three consecutive phases.First,(phase 1)the main surfactant(AOS)was selected among a series of commercial candidates in static conditions.Then,(phase 2)the betaine booster to be combined with the previously selected AOS was chosen and their ratio optimized in static conditions.Subsequently,(phase 3)the surfactant/booster ratio was optimized under dynamic conditions in a porous medium in the absence and the presence of oil.As a result of this study,a mixture of an AOS C14-C16 and cocamidopropyl hydroxysultaine(CAPHS)was selected as the one having the best performance.The designed formulation was proven to be robust in a wide range of conditions.It generated a strong and stable foam at reservoir conditions,overcoming variations in salinity and foam quality,and tolerated the presence of oil.展开更多
基金the National Key Basic Research Program of China (973 Program Grant No. G19990225)
文摘A pseudo-three-dimensional model of potentiality prediction is proposed for enhanced oil recovery, based on the streamline method described in this article. The potential distribution of the flow through a porous medium under a complicated boundary condition is solved with the boundary element method. Furthermore, the method for tracing streamlines between injection wells and producing wells is presented. Based on the results, a numerical solution can be obtained by solving the seepage problem of the stream-tube with consideration of different methods of Enhanced Oil Recovery（EOR）. The advantage of the method given in this article is that it can obtain dynamic calculation with different well patterns of any shape by easily considering different physicochemical phenomena having less calculation time and good stability. Based on the uniform theory basis-streamline method, different models, including CO2 miscible flooding, polymer flooding, alkaline/surfactant/polymer flooding and microbial flooding, are established in this article.
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.
基金The project supported by National Natural Science Foundation of China(No.51991364,51974347)the Major Scientific and Technological Projects of CNPC under Grant ZD2019-184-002。
文摘Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.
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supported by Project of Sinopec Northwest Oilfield Company(Grant No.202108ZB0046).
文摘The development of fractured-vuggy carbonate reservoirs is extremely difficult because of the complex fractured-vuggy structure and strong heterogeneity.Foam flooding is a potential enhanced oil recovery(EOR)technology in fractured-vuggy carbonate reservoirs.Based on the similarity criterion,three types of 2D visual physical models of the fractured-vuggy structure were made by laser ablation technique,and a 3D visual physical model of the fractured-vuggy reservoir was made by 3D printing technology.Then the physical analog experiments of foam flooding were carried out in these models.The experimental results show that foam can effectively improve the mobility ratio,control the flow velocity of the fluid in different directions,and sweep complex fracture networks.The effect of foam flooding in fractures can be improved by increasing foam strength and enhancing foam stability.The effect of foam flooding in vugs can be improved by reducing the density of the foam and the interfacial tension between foam and oil.Three types of microscopic residual oil and three types of macroscopic residual oil can be displaced by foam flooding.This study verifies the EOR of foam flooding in the fractured-vuggy reservoir and provides theoretical support for the application of foam flooding in fractured-vuggy reservoirs.
基金financial support of the National Nature Science Foundation of China(Grant No.U20B6003)the Natural Science Foundation of Shandong Province,China(ZR2020QE106).
文摘Steam flooding with the assistance of carbon dioxide (CO_(2)) and chemicals is an effective approach for enhancing super heavy oil recovery. However, the promotion and application of CO_(2) and chemical agent-assisted steam flooding technology have been restricted by the current lack of research on the synergistic effect of CO_(2) and chemical agents on enhanced steam flooding heat transfer. The novel experiments on CO_(2)–chemicals cooperate affected steam condensation and seepage were conducted by adding CO_(2) and two chemicals (sodium dodecyl sulfate (SDS) and the betaine temperature-salt resistant foaming agent ZK-05200).According to the experimental findings, a “film” formed on the heat-transfer medium surface following the co-injection of CO_(2) and the chemical to impede the steam heat transfer, reducing the heat transfer efficiency of steam, heat flux and condensation heat transfer coefficient. The steam seepage experiment revealed that the temperature at the back end of the sandpack model was dramatically raised by 3.5–12.8 °C by adding CO_(2) and chemical agents, achieving the goal of driving deep-formation heavy oil. The combined effect of CO_(2) and SDS was the most effective for improving steam heat transfer, the steam heat loss was reduced by 6.2%, the steam condensation cycle was prolonged by 1.3 times, the condensation heat transfer coefficient was decreased by 15.5%, and the heavy oil recovery was enhanced by 9.82%. Theoretical recommendations are offered in this study for improving the CO_(2)–chemical-assisted steam flooding technique.
文摘The presence of a bottom water(BW)layer in heavy oil reservoirs can present substantial problems for efficient oil recovery for all recovery techniques.Hence,it is necessary to know how particular production processes are affected by different BW layer thicknesses,and how standard production procedures can be adapted to handle such reservoirs.Toe-to-heel air injection(THAI)is a thermally efficient process,generating in situ energy in the reservoir by burning a fraction of the oil-in-place as coke and has the potential to economically and environmentally friendly work in reservoirs with BW layer.However,to ascertain that,studies are needed first.These are conducted via numerical simulations using commercial reservoir thermal simulator,CMG STARS.This work has shown that the shape of the combustion zone in THAI remains forward-leaning even in the presence of a BW layer,indicating that the process is stable,and that there is no oxygen bypassing of the combustion front.However,the oil recovery rate is highly negatively affected by how large the thickness of the BWzone is,and the severity of such effect is determined to be proportional to the thickness of the BW layer.This study also shows that there is a period of low oil production rate which corresponds to mobilised oil displacement into the BW zone which in turn causes a surge in water production rate.The practical implication of this is that prolonged period of low oil production rates will expose companies and/or investors to higher risk due to the oil market volatility.In this study,it is also revealed that the height of the mobilised oil that is displaced into the BW zone equates to that of the displaced and replaced water thereby implying that when the BW layer thickness is 50%that of the oil layer(OL),less than 50%of the mobilised oil will be recovered when the entire reservoir is swept by the combustion front.Therefore,conclusively,applying the THAI process in its conventional form in reservoirs containing bottom water is not recommended,and as a result,a ne
文摘Solvents are generally used to reduce the viscosity of heavy crude oil and ultimately enhance oil recovery.Recently,a new method has been introduced where nanoparticles(NPs)are exploited to induce enhanced oil recovery owing to their ability to improve the mobility ratio,dampen the interfacial tension,and alter rock wett-ability.This study investigated the integration of nano-alumina(Al_(2)O_(3))NPs with an n-hexane solvent.In parti-cular,a Brookfield viscometer has been used to measure the crude oil viscosity and it has been found that NPs can effectively lead to a significant decrease in the overall oil viscosity(70 cp using the solvent only,45 cp when NPs are added).
文摘The study of flow through porous media has been of cardinal gravity in oil and gas applications like enhanced oil recovery(EOR),acidizing,fracturing,etc.One of the most anticipated apprehensions is that the core flooding and simulation have become prevalent to understand the flow through porous media.This study aims at simulating and analyzing the effect of alkaline surfactant flooding through heterogeneous permeability conditions in the lab-scale methods.The conventional methods of core flood deal with the effective permeability of the system without considering the effect of heterogeneity within the core.The heterogeneous studies are conducted by simulating a finely meshed 2-D axisymmetric model of the sand pack.The novel Karanj oil surfactant extracted from Pongamia Pinnata,and partially hydrolyzed polyacryl amide polymer are considered for the physicochemical properties of displacing fluid used in the simulations.Different heterogeneity combinations and displacing fluid injection flow rates are introduced for a single absolute permeability system.Results indicate a trend of oil recovery upright with increasing vertical permeability.A lower areal sweep efficiency and early breakthrough are observed in models with high horizontal permeabilities.Further,the effect of heterogeneity on oil recovery is reduced with the increase in injection flow rates of displacing fluid.The present work utilizes computational fluid dynamics to model multiphase flow through a heterogeneous permeability media and its effect on oil recovery.
文摘A novel concept of treating oil reservoirs by nanofluids is being developed to improve oil recovery and reduce the trapped oil in hydrocarbon reservoirs.Nanoparticles show great potential in enhancing oil recovery under ambient conditions.In this paper,the approaches of wettability alteration by using nanofluid,stability of nanofluids,and the most reliable wettability alteration mechanisms associated with variant types of nanoparticles have been reviewed.Moreover,the parameters that have a significant influence on nanofluid flooding have been discussed.Finally,the recent studies of the effect of nanoparticles on wettability alteration have been summarised and analysed.Furthermore,this paper presents possible opportunities and challenges regarding wettability alteration using nanofluids.
文摘Carbon dioxide(CO2) flooding is one of the most globally used EOR processes to enhance oil recovery.However,the low gas viscosity and density result in gas channeling and gravity override which lead to poor sweep efficiency.Foam application for mobility control is a promising technology to increase the gas viscosity,lower the mobility and improve the sweep efficiency in the reservoir.Foam is generated in the reservoir by co-injection of surfactant solutions and gas.Although there are many surfactants that can be used for such purpose,their performance with supercritical CO2(ScCO2) is weak causing poor or loss of mobility control.This experimental study evaluates a newly developed surfactant(CNF) that was introduced for ScCO2 mobility control in comparison with a common foaming agent,anionic alpha olefin sulfonate(AOS) surfactant.Experimental work was divided into three stages:foam static tests,interfacial tension measurements,and foam dynamic tests.Both surfactants were investigated at different conditions.In general,results show that both surfactants are good foaming agents to reduce the mobility of ScCO2 with better performance of CNF surfactant.Shaking tests in the presence of crude oil show that the foam life for CNF extends to more than 24 h but less than that for AOS.Moreover,CNF features lower critical micelle concentration(CMC),higher adsorption,and smaller area/molecule at the liquid-air interface.Furthermore,entering,spreading,and bridging coefficients indicate that CNF surfactant produces very stable foam with light crude oil in both deionized and saline water,whereas AOS was stable only in deionized water.At all conditions for mobility reduction evaluation,CNF exhibits stronger flow resistance,higher foam viscosity,and higher mobility reduction factor than that of AOS surfactant.In addition,CNF and ScCO2 simultaneous injection produced 8.83% higher oil recovery than that of the baseline experiment and 7.87% higher than that of AOS.Pressure drop profiles for foam flooding using CNF was slightly higher
基金supported by Science Foundation of China University of Petroleum,Beijing(No.2462022BJRC001,2462021YJRC012)the funding from State Key Laboratory of Petroleum Resources and Prospecting(No.PRP/indep-1-2103)
文摘Injecting CO2into hydrocarbon reservoirs can enhance the recovery of hydrocarbon resources,and simultaneously,CO2can be stored in the rese rvoirs,reducing considerable amount of carbon emissions in the atmosphere.However,injected CO_(2)tends to go through fractures,high-permeability channels and streaks present in reservoirs,resulting in inefficient hydrocarbon recovery coupled with low CO_(2)storage performance.Conformance treatments with CO_(2)-resistant crosslinked polymer gels were performed in this study to mitigate the CO_(2)channeling issue and promote the synergy between enhanced oil recovery(EOR) and subsurface sequestration of CO_(2).Based on a typical low-permeability CO_(2)-flooding reservoir in China,studies were performed to investigate the EOR and CO_(2)storage performance with and without conformance treatment.The effect of permeability contrast between the channels and rese rvoir matrices,treatment size,and plugging strength on the efficiency of oil recovery and CO_(2)storage was systematically investigated.The results indicated that after conformance treatments,the CO_(2)channeling problem was mitigated during CO_(2)flooding and storage.The injected CO_(2)was more effectively utilized to recover the hydrocarbons,and entered wider spectrum of pore spaces.Consequently,more CO_(2)was trapped underground.Pronounced factors on the synergy of EOR and CO_(2)storage were figured out.Compared with the treatment size,the CO_(2)storage efficiency was more sensitive to the plugging strength of the conformance treatment materials.This observation was important for conformance treatment design in CCUS-EOR projects.According to this study,the materials should reduce the channel permeability to make the channel/matrix permeability ratio below 30.The results demonstrate the importance of conformance treatment in maximizing the performance of CCUS-EOR process to achieve both oil recovery improvement and efficient carbon storage.This study provides guidelines for successful field applications of CO_(2)transport co
文摘Applying chemical flooding in petroleum reservoirs turns into interesting subject of the recent researches.Developing strategies of the aforementioned method are more robust and precise when they consider both economical point of views(net present value(NPV))and technical point of views(recovery factor(RF)).In the present study huge attempts are made to propose predictive model for specifying efficiency of chemical flooding in oil reservoirs.To gain this goal,the new type of support vector machine method which evolved by Suykens and Vandewalle was employed.Also,high precise chemical flooding data banks reported in previous works were employed to test and validate the proposed vector machine model.According to the mean square error(MSE),correlation coefficient and average absolute relative deviation,the suggested LSSVM model has acceptable reliability;integrity and robustness.Thus,the proposed intelligent based model can be considered as an alternative model to monitor the efficiency of chemical flooding in oil reservoir when the required experimental data are not available or accessible.
文摘The Surface engineering of nanoparticles has contributed to the development of nanoscience and nanotechnology by designing of new material depends on their surface modifier with series of functional properties and applications.The dispersed nanoparticles can change or modify the interfacial properties in liquid-liquid system in aqueous phase if their surface is modified by ionic surfactant.The interfacial energy in nanoparticles-brine system,the ions tends to modify the transport phenomena in pore channels and improve the recovery.The use of the suspension of the particles at nanoscales can offer some advantages of induced sedimentation stability by surface force easily counter balance the force of gravity.This happened due to their nanosize,nanostructure,high volume to surface ratio and strong rock fluid interaction.It also influences the emulsion stability and alters the surface characteristics of surfactant and polymer within the rock in porous medium.Some of the problems associated with conventional EOR processes have been solved by nanoscience applications due to their potential response to reduce the interfacial tension at low to ultra-low level,wettability reversal and improvement in rheology of formation fluids.The large specific surface area,high reactivity,toughness and other properties of Nanoparticles can immensely improve the oil mobility compare to conventional EOR.This paper updates the latest review,experimental evidences and re-interpretation of past research data and applications in respect of silica and titanium dioxide nanoparticles in different environment within surfactant(s),polymer(s),polymer-surfactant EOR processes.The nanotechnology therefore is an effective and alternate solution to brush up the traditional EOR approach with state of art technology which can revolutionize the total oil and gas industry and can contributes significantly to enhance the economics of oil field industry.
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Based on the analysis of recent projections by the International Energy Agency(IEA),to meet the growing and subsequently declining demands of oil from now to 2040,we need up to around 770 billion barrels of oil.Since the worldwide total proved reserves of easy-and-cheaper-to-produce conventional oils is roughly only 520.2 billion barrels,the remaining 249.8 billion barrels must be obtained from unconventional petroleum resources(i.e.heavy oils and bitumen).These resources are however very difficult and costly to upgrade and produce due to their inherently high asphaltene contents which are reflected in their very high viscosities and large densities.However,still they should prove attractive development prospects if,as much as practicably possible,their upgrading can be performed in conjunction with in situ or downhole catalytic upgrading processes.Such projects will contribute significantly towards smoother and greener transition to full decarbonisation.Advanced technologies,such as the toe-to-heel air injection coupled to its add-on in situ catalytic process(i.e.THAI-CAPRI processes),have the potential to develop these reserves,but require further developmental understanding to realise their full capability.In this work,a new detailed procedure for numerically simulating the THAI-CAPRI processes is presented.The numerical model is made-up of Athabasca-type bitumen and it has a horizontal producer(HP)well that is surrounded by an annular layer of alumina-supported cobalt-oxide-molybdenum-oxide(CoMo/γ-Al2O3)catalyst.The simulation is performed using the computer modelling group(CMG)reservoir simulator,STARS.This new work has shown that the choice of the frequency factor of the catalytic reactions allowed model validation based on the degree of catalytic upgrading in form of API gravity.Overall,the work herein identifies the important parameters,such as API gravity,peak temperature,oil production rate,cumulative oil production,produced oxygen concentration,temperature distribution profile,extent of coke depositio
文摘According to the analysis of the 2020 estimates of the International Energy Agency(2020),the world will require up to 770 billion barrels of oil from now to 2040.However,based on the British Petroleum(BP)statistical review of world energy 2020,the world-wide total reserve of the conventional light oil is only 520.2 billion barrels as at the end of 2019.That implies that the remaining 249.8 billion barrels of oil urgently needed to ensure a smooth transition to a decarbonised global energy and economic systems is provided must come from unconventional oils(i.e.heavy oils and bitumen)reserves.But heavy oils and bitumen are very difficult to produce and the current commercial production technologies have poor efficiency and release large quantities of greenhouse gases.Therefore,these resources should ideally be upgraded and produced using technologies that have greener credentials.This is where the energy-efficient,environmentally friendly,and self-sustaining THAI-CAPRI coupled in situ combustion and in situ catalytic upgrading process comes in.However,the novel THAI-CAPRI process is trialled only once at field and it has not gained wide recognition due to poor understanding of the optimal design parameters and procedures.Hence,this work reports the first ever results of investigations of the effect of operating pressure on the performance of the THAI-CAPRI process.Two experimental scale numerical models of the process based on Athabasca tar sand properties were run at pressures of 8000 kPa and 500 kPa respectively using CMG STARS.This study has shown that the higher the operating pressure,the larger the API gravity and the higher the cumulative volume of high-quality oil is produced(i.e.a 2300 cm3 of z24 oAPI oil produced at 8000 kPa versus the 2050 cm3 of z17.5 oAPI oil produced at 500 kPa).The study has further shown that despite presence of annular catalyst layer,the THAI-CAPRI process operates stably.However,it is found that a more stable and safer operation of the process can only be achieved at optimal pressu
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.
基金funded by the Centro para el Desarrollo Tecnologico Industrial(CDTI)of the Spanish Ministry of Science and Innovation(IDI-20170503)the Fundacion Cepsa with the Escuela Tecnica Superior de Ingenieros de Minas y Energia of the Universidad Politecnica de Madrid(UPM)。
文摘This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions(high salinity,high divalent ion concentration,high temperature,light oil,and hydrocarbon injection gas)in a sandstone reservoir.For this,we selected anionic Alpha Olefin Sulfonate(AOS)surfactants and studied their synergistic effects in mixtures with zwitterionic betaines to enhance foam performance.The laboratory workflow used to define the best formulation followed a de-risking approach in three consecutive phases.First,(phase 1)the main surfactant(AOS)was selected among a series of commercial candidates in static conditions.Then,(phase 2)the betaine booster to be combined with the previously selected AOS was chosen and their ratio optimized in static conditions.Subsequently,(phase 3)the surfactant/booster ratio was optimized under dynamic conditions in a porous medium in the absence and the presence of oil.As a result of this study,a mixture of an AOS C14-C16 and cocamidopropyl hydroxysultaine(CAPHS)was selected as the one having the best performance.The designed formulation was proven to be robust in a wide range of conditions.It generated a strong and stable foam at reservoir conditions,overcoming variations in salinity and foam quality,and tolerated the presence of oil.
