Evaluation of the coupled impact of silicon oxide nanoparticles and low-salinity water on the wettability alteration of Berea sandstones

This study investigated experimentally the coupled effects of hydrophilic SiO_(2) nanoparticles(NPs)and low-salinity water(LSW)on the wettability of synthetic clay-free Berea sandstone.Capillary pressure,interfacial tension(IFT),contact angle,Zeta potential,and dynamic displacement measurements were performed at various NP mass fractions and brine salinities.The U.S.Bureau of Mines(USBM)index was used to quantify the wettability alteration.Furthermore,the NP stability and retention and the effect of enhanced oil recovery by nanofluid were examined.The results showed that LSW immiscible displacement with NPs altered the wettability toward more water wet.With the decreasing brine salinity and increasing NP mass fraction,the IFT and contact angle decreased.The wettability alteration intensified most as the brine salinity decreased to 4000 mg/L and the NP mass fraction increased to 0.075%.Under these conditions,the resulting incremental oil recovery factor was approximately 13 percentage points.When the brine salinity was 4000 mg/L and the NP mass fraction was 0.025%,the retention of NPs caused the minimum damage to permeability.

Wettability alteration of organo-vermiculites induced by layer charge and tailored bis-N-heterocyclic quaternary ammonium salts

Wettability is an important surface property that deserves to further explore the factors on its alteration.Series of bis-N-heterocyclic quaternary ammonium salts with different spacer length and N-heterocyclic headgroups(morpholinium(BMMB,BMMD and BMMH),piperidinium(BPMH)and piperazinium(BMPMH))have been synthesized and employed for altering the wettability of vermiculite and its derivates(Vts)treated by Li^(+)-saturated heating method.The results of X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TG-DTG),scanning electron microscopy(SEM)and N_(2)adsorption/desorption isotherms indicate that all of the bis-N-heterocyclic quaternary ammonium salts have been successfully inserted into the vermiculite layers,leading to the organic monolayer.The results of capillary rise tests combined with Lipophilic to Hydrophilic Ratio(LHR)values unveil the wettability alteration of the organo-Vts.As the layer charge decreases,the hydrophilicity of the organo-Vts gradually increases,which is probably caused by the decline in binding sites.As the result of the change in spacer length of modifier,the wetting properties of morpholinium-based organo-Vts change in order of BMMD-Vts>BMMH-Vts>BMMB-Vts,and difference in N-heterocyclic headgroups leads to the sequence of wettability:BMPMH-Vts>BPMH-Vts>BMMH-Vts.Layer charge of Vt,spacer length and the type of the N-heterocyclic headgroup of modifier have the synergistic effect on the regulation of the wettability.

Investigation of the effect of diethylene triamine pentaacetic acid chelating agent as an enhanced oil recovery fluid on wettability alteration of sandstone rocks

This study used the diethylene triamine pentaacetic acid(DTPA)-seawater(SW)system to modify the sandstone rock wettability and enhance oil recovery.The investigation involved conducting wettability measurement,Zeta potential measurement,and spontaneous imbibition experiment.The introduction of 5%DTPA-sW solution resulted in a significant decrease in the rock-oil contact angle from 143°to 23,along with a reduction in the Zeta potential from-2.29 mV to-13.06 mV,thereby altering the rock surface charge and shifting its wettability from an oil-wet state to a strongly water-wet state.The presence or absence of potential determining ions(Ca^(2+),Mg^(2+),SO_(4)^(2-))in the solution did not impact the effectiveness of DTPA in changing the rock wettability.However,by tripling the concentration of these ions in the solution,the performance of 5%DTPA-SW solution in changing wettability was impaired.Additionally,spontaneous imbibition tests demonstrated that the 5%DTPA-SW solution led to an increase in oil recovery up to 39.6%.Thus,the optimum mass fraction of DTPA for changing sandstone wettability was determined to be5%.

Surfactant induced reservoir wettability alteration:Recent theoretical and experimental advances in enhanced oil recovery

Reservoir wettability plays an important role in various oil recovery processes.The origin and evolution of reservoir wettability were critically reviewed to better understand the complexity of wettability due to interactions in crude oil-brine-rock system,with introduction of different wetting states and their influence on fluid distribution in pore spaces.The effect of wettability on oil recovery of waterflooding was then summarized from past and recent research to emphasize the importance of wettability in oil displacement by brine.The mechanism of wettability alteration by different surfactants in both carbonate and sandstone reservoirs was analyzed,concerning their distinct surface chemistry,and different interaction patterns of surfactants with components on rock surface.Other concerns such as the combined effect of wettability alteration and interfacial tension （IFT） reduction on the imbibition process was also taken into account.Generally,surfactant induced wettability alteration for enhanced oil recovery is still in the stage of laboratory investigation.The successful application of this technique relies on a comprehensive survey of target reservoir conditions,and could be expected especially in low permeability fractured reservoirs and forced imbibition process.

The effect of nanoparticles on wettability alteration for enhanced oil recovery: micromodel experimental studies and CFD simulation

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.

Wettability alteration and oil recovery by spontaneous imbibition of smart water and surfactants into carbonates

Naturally fractured carbonate reservoirs have very low oil recovery efficiency owing to their wettability and tightness of matrix.However,smart water can enhance oil recovery by changing the wettability of the carbonate rock surface from oilwet to water-wet,and the addition of surfactants can also change surface wettability.In the present study,the effects of a solution of modified seawater with some surfactants,namely C12 TAB,SDS,and TritonX-100(TX-100),on the wettability of carbonate rock were investigated through contact angle measurements.Oil recovery was studied using spontaneous imbibition tests at 25,70,and 90°C,followed by thermal gravity analysis to measure the amount of adsorbed material on the carbonate surface.The results indicated that Ca2+,Mg2+,and SO42-.ions may alter the carbonate rock wettability from oil-wet to water-wet,with further water wettability obtained at higher concentrations of the ions in modified seawater.Removal of NaCl from the imbibing fluid resulted in a reduced contact angle and significantly enhanced oil recovery.Low oil recoveries were obtained with modified seawater at 25 and 70°C,but once the temperature was increased to 90°C,the oil recovery in the spontaneous imbibition experiment increased dramatically.Application of smart water with C12 TAB surfactant at 0.1 wt%changed the contact angle from 161°to 52°and enhanced oil recovery to 72%,while the presence of the anionic surfactant SDS at 0.1 wt%in the smart water increased oil recovery to 64.5%.The TGA analysis results indicated that the adsorbed materials on the carbonate surface were minimal for the solution containing seawater with C12 TAB at 0.1 wt%(SW+CTAB(0.1 wt%)).Based on the experimental results,a mechanism was proposed for wettability alteration of carbonate rocks using smart water with SDS and C12 TAB surfactants.

Effect of a synthesized anionic fluorinated surfactant on wettability alteration for chemical treatment of near-wellbore zone in carbonate gas condensate reservoirs

The pressure drop during production in the near-wellbore zone of gas condensate reservoirs causes condensate formation in this area.Condensate blockage in this area causes an additional pressure drop that weakens the effective parameters of production,such as permeability.Reservoir rock wettability alteration to gas-wet through chemical treatment is one of the solutions to produce these condensates and eliminate condensate blockage in the area.In this study,an anionic fluorinated surfactant was synthesized and used for chemical treatment and carbonate rock wettability alteration.The synthesized surfactant was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis.Then,using surface tension tests,its critical micelle concentration(CMC)was determined.Contact angle experiments on chemically treated sections with surfactant solutions and spontaneous imbibition were performed to investigate the wettability alteration.Surfactant adsorption on porous media was calculated using flooding.Finally,the surfactant foamability was investigated using a Ross-Miles foam generator.According to the results,the synthesized surfactant has suitable thermal stability for use in gas condensate reservoirs.A CMC of 3500 ppm was obtained for the surfactant based on the surface tension experiments.Contact angle experiments show the ability of the surfactant to chemical treatment and wettability alteration of carbonate rocks to gas-wet so that at the constant concentration of CMC and at 373 K,the contact angles at treatment times of 30,60,120 and 240 min were obtained 87.94°,93.50°,99.79°and 106.03°,respectively.However,this ability varies at different surfactant concentrations and temperatures.The foamability test also shows the suitable stability of the foam generated by the surfactant,and a foam half-life time of 13 min was obtained for the surfactant at CMC.

The effect of nanoparticles on reservoir wettability alteration:a critical review

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.

Enhancing the spontaneous imbibition rate of water in oil-wet dolomite rocks through boosting a wettability alteration process using carbonated smart brines

Most fractured carbonate oil reservoirs have oil-wet rocks.Therefore,the process of imbibing water from the fractures into the matrix is usually poor or basically does not exist due to negative capillary pressure.To achieve appropriate ultimate oil recovery in these reservoirs,a water-based enhanced oil recovery method must be capable of altering the wettability of matrix blocks.Previous studies showed that carbonated water can alter wettability of carbonate oil-wet rocks toward less oil-wet or neutral wettability conditions,but the degree of modification is not high enough to allow water to imbibe spontaneously into the matrix blocks at an effective rate.In this study,we manipulated carbonated brine chemistry to enhance its wettability alteration features and hence to improve water imbibition rate and ultimate oil recovery upon spontaneous imbibition in dolomite rocks.First,the contact angle and interfacial tension(IFT)of brine/crude oil systems were measured for several synthetic brine samples with different compositions.Thereafter,two solutions with a significant difference in WAI(wettability alteration index)but approximately equal brine/oil IFT were chosen for spontaneous imbibition experiments.In the next step,spontaneous imbibition experiments at ambient and high pressures were conducted to evaluate the ability of carbonated smart water in enhancing the spontaneous imbibition rate and ultimate oil recovery in dolomite rocks.Experimental results showed that an appropriate adjustment of the imbibition brine(i.e.,carbonated smart water)chemistry improves imbibition rate of carbonated water in oil-wet dolomite rocks as well as the ultimate oil recovery.

Application of gas wettability alteration to improve methane drainage performance:A case study

Hydraulic fracturing technique is widely used for methane drainage and has achieved good effects in numerous coal mines,but negative effects may occur as the fracturing fluids are absorbed into the coal seam.Gas wettability alteration(GWA)technology can be used as it can enhance the gas and water mobility during dewatering process as a result of capillary pressure change.However,there have been few reported field tests in coal mines using GWA technology.This paper describes a pilot-scale field test in Xinjing coal mine,Yangquan,China.The fluorocarbon surfactants perfluorooctyl methacrylate monomer-containing polymethacrylate(PMP)was used to alter the wettability of coal seam to strong gas-wetness during the hydraulic fracturing process.The study focuses on the comparison of two boreholes(Boreholes#9 and#10)and one other borehole(Borehole#8)with and without using GWA approach.A well-defined monitoring program was established by measuring the dewatering volume of the fracturing fluid and the drainage volume of methane as well as the concentration.The field test results showed that the average methane drainage rates of Boreholes#9(39.28 m^(3)/d)and#10(51.04 m^(3)/d)with GWA treatment exceeded that of Borehole#8(21.09 m^(3)/d)without GWA treatment,with an increase of 86.3%and 142.1%,respectively.The average methane concentrations of Boreholes#9(4.05%)and#10(6.18%)were 64.6%and 151.2%higher than that of Borehole#8(2.46%),respectively.On the other hand,the dewatering ratio of Boreholes#9(4.36%)and#10(3.11%)was almost 19 times and 13 times greater than that of Borehole#8(0.22%).These field test results were in agreement with the experimental data.The significant increase in both methane concentration and dewatering ratio demonstrated that GWA technology could be applied for enhanced methane drainage in coal mines.Important lessons learned at Xinjing coal mine might be applied to other coal mines in China and elsewhere.

Wettability alteration and retention of mixed polymer-grafted silica nanoparticles onto oil-wet porous medium

Enhanced oil recovery(EOR)processes are applied to recover trapped or residual oil in the reservoir rocks after primary and secondary recovery methods.Changing the wettability of the rock from oil-wet to water-wet is named wettability alteration.It is an important factor for EOR.Due to their unique properties,nanoparticles have gained great attention for improving oil recovery.Despite the promising results,the main challenges of applying nanoparticles are related to the colloidal stability of the nanofuids in the harsh conditions of the reservoirs.In recent years,polymer-grafted nanoparticles have been considered as novel promising materials for EOR.The obtained results showed that adding a hydrophobic agent trimethoxy(propyl)silane on the surface of modifed silica nanoparticles with polyethylene glycol methyl ether has an efective role in improving retention and wettability alteration,especially in the oil-wet substrate due to hydrophobic interaction.The modifed silica nanoparticle by mixed polyethylene glycol methyl ether(Mn~5000)and trimethoxy(propyl)silane showed a proper performance at a concentration of 1000 ppm and a salinity range of 2000-40,000 ppm.The obtained fndings can help for a better understanding of the silica nanofuid modifcation with both hydrophilic and hydrophobic agents for the EOR application of near-wellbore.

Adsorption behavior and wettability alteration of bis-imidazolium salts on vermiculite:Experimental and theoretical studies

For further understanding the wettability alteration induced by organic salts,series of bis-imidazolium salts(EBMI,TBMI,HBMI,OBMI and DBMI) were employed for investigating their adsorption behavior and wettability alteration on vermiculite(Vt) by experimental and theoretical studies.The characterization results indicated that all bis-imidazolium salts had been loaded on Vts.The adsorption results showed that EBMI,TBMI,HBMI,OBMI and DBMI on Vt reached equilibrium of 0.159,0.156,0.145,0.114 and 0.084 mmol g-1 around 30 min at 25℃,respectively,which were sensitive to ionic strength and pH.Langmuir,statistical physical modelling and pseudo-second-order models could be well fitted with the adsorption data,and thermodynamic parameters suggested that the adsorption processes of bis-imidazolium salts were endothermic and spontaneous,indicating that the resultant bis-imidazolium salts could be self-assembled onto Vt in the form of the monolayer.Results of molecular dynamic simulation showed that bis-imidazolium salts were adsorbed on Vt with the lying-flat configuration,and the electrostatic interaction acted as the main interaction mechanism,which were consistent with that obtained experimentally.Changes of wettability of Vt induced by bis-imidazolium salts were verified by capillary rise experiments.Interestingly,the wettability of organo-Vts varied with the spacer length and the order was as follows:EBMI-Vt <TBMI-Vt <HBMI-Vt <OBMI-Vt <DBMI-Vt,which could be explained by their arrangements,hydrophobicity as well as the interaction energies.The longer the spacers of bisimidazolium salts,the greater the absolute values of the interaction energy,the less the adsorbed bisimidazolium salts,while the more hydrophobic of organo-Vt.This work aimed at revealing the adsorption behavior,mechanism as well as effect of bis-imidazolium salts on wettability alteration of negatively charged mineral surface,providing some information for the selection of flooding agent for enhanced oil recovery and wettability modifier.

Wettability alteration analysis of smart water/novel functionalized nanocomposites for enhanced oil recovery

Smart water flooding,as a popular method to change the wettability of carbonate rocks,is one of the interesting and challenging issues in reservoir engineering.In addition,the recent studies show that nanoparticles have a great potential for application in EOR processes.However,little research has been conducted on the use of smart water with nanoparticles in enhanced oil recovery.In this study,stability,contact angle and IFT measurements and multi-step core flooding tests were designed to investigate the effect of the ionic composition of smart water containing SO4^2- and Ca^2+ ions in the presence of nanofluid on EOR processes.The amine/organosiloxane@Al2O3/SiO2(AOAS) nanocomposite previously synthesized using co-precipitation-hydrothermal method has been used here.However,for the first time the application of this nanocomposite along with smart water has been studied in this research.Results show that by increasing the concentrations of calcium and sulfate ions in smart water,oil recovery is improved by 9% and 10%,respectively,compared to seawater.In addition,the use of smart water and nanofluids simultaneously is very effective on increasing oil recovery.Finally,the best performance was observed in smart water containing two times of sulfate ions concentration(SW2 S) with nanofluids,showing increased efficiency of about 7.5%.

Wettability alteration by magnesium ion binding in heavy oil/brine/chemical/sand systems—analysis of hydration forces

In laboratory sandpack tests for heavy oil re-covery by alkaline flooding, it was found that wettability alteration of the sand had a significant impact on oil recovery. In this work, a heavy oil of 14? API was used to examine the effect of organic acids in the oil and water che- mistry on wettability alteration. From interfacial tension measurements and sand surface composition analysis, it was concluded that the water-wet sand became preferentially oil-wet by magnesium ion binding. The presence of Mg2+ in the heavy oil/Na2CO3 solution/sand system increased the oil/water interfacial tension. This confirmed the hypothesis that magnesium ion combined with the ionized organic acids to form magnesium soap at oil/water interface. Under alkaline condition, the ionized organic acids in the oil phase partition into the water phase and subsequently adsorb on the sand surfaces. The analysis of sand surface composition sugg- ested that more ionized organic acids adsorb- ed on the sand surface through magnesium ion binding. The attachment of more organic acids on the sand surface changed hydration forces, making the sand surface more oil-wet.

表面活性剂对油湿性致密砂岩渗吸作用与界面协同效应

为探索不同表面活性剂对油湿性致密储层的渗吸排油效果,系统对比阴离子、非离子、阳离子和两性离子4大类型17种表面活性剂渗吸排油效率,分析不同类型活性剂对致密储层渗吸排驱效果的差异及其机制,开发致密储层高效排驱的表面活性剂配方,确立致密储层高效排驱对表面活性剂界面张力和接触角性能的界限。结果表明:试验条件下阴离子、非离子表面活性剂对致密岩心的渗吸排油效率在18.4%~27.2%,显著高于阳离子、两性离子表面活性剂的0~2.4%;阳离子和两性离子表面活性剂不适宜单独作为油湿性致密储层的渗吸排油剂;润湿性调控能力是表面活性剂产生高效渗吸排油的主要原因,界面张力和接触角存在协同效应;复合渗吸排油剂渗吸排油效率超过38%;表面活性剂对致密储层高效渗吸排油的接触角和界面张力分别为15°~35°、0.1~2 mN·m^(-1),对应的N^(-1)B大于15,毛管力是渗吸排油的主要动力。

致密砂岩油藏纳米乳液渗吸增产作用机理

纳米乳液作为一种纳米级胶体分散体系,因其优异的界面性能以及提高采收率效果被广泛应用于非常规油藏开发。基于低能乳化法制备了水包油型纳米乳液体系,通过室内实验明确纳米乳液静态吸附性能、润湿反转性能以及自发渗吸的内在联系,并分析纳米乳液在致密砂岩油藏中的渗吸增产作用机理。实验结果表明:纳米乳液的平均粒径小于10nm,满足进入致密砂岩绝大部分孔喉的粒径要求,在致密孔喉内能充分扩散运移,从而扩大渗吸作用范围。纳米乳液的临界胶束质量分数为0.015%,能够有效降低油水界面张力至2 mN/m左右。纳米乳液的吸附等温线符合Langmuir吸附模型,其润湿反转机理以吸附机理为主。纳米乳液能够增溶原油,并通过乳化作用进一步分散原油,减小乳状液中油滴尺寸,减弱油滴通过孔喉时的贾敏效应,降低渗流阻力。岩心润湿性会影响渗吸采收率,随着岩心亲水性增强而增加,不同润湿性岩心自发渗吸时孔隙动用程度存在差异,加入纳米乳液能显著提高油湿岩心内小孔渗吸采收率。同时,增加纳米乳液浓度与边界开放程度可以提高渗吸采收率,这主要是由于致密砂岩自发渗吸受毛细管力主导,边界开放程度增加能够扩大纳米乳液接触面积,纳米乳液浓度增加能够增强润湿反转作用与乳化作用,从而增强自发渗吸效果。

两亲碳点的表界面性能与驱油性能

高界面活性纳米驱油材料的制备是纳米技术在超低渗透油藏提高采收率中应用的关键问题。考察了自制两亲碳点(CDs)的表界面活性,研究了无机盐和老化温度对两亲CDs界面活性的影响,并研究了两亲CDs的油膜剥离性能和润湿反转性能,通过岩心驱替实验评价了两亲CDs的驱油性能。研究结果表明,两亲CDs具有与表面活性剂相似的表面张力曲线,其临界胶束浓度和平衡表面张力分别为150.21 mg/L和28.43 mN/m。在60℃、100 g/L NaCl和25 g/L CaCl_(2)条件下仍能保持较高的界面活性,可将油水界面张力由0.578 mN/m分别降低至0.032 mN/m和0.015 mN/m。此外,两亲CDs具有优异的油膜剥离性能和润湿反转性能,经两亲CDs处理后,油膜面积分别减少了79.3%,并且具有润湿反转能力,可将亲油玻璃片表面的水滴接触角由109.2°降至44.8°。岩心驱油实验表明,在85 g/L NaCl和10 g/L CaCl_(2)条件下,两亲CDs驱油效率为17.4%,具有较好的耐盐性。因此,两亲CDs作为一种高界面活性的耐高温耐盐纳米颗粒,在高温高盐油藏提高采收率方面具有广阔的应用前景。

Effects of modified graphene oxide(GO) nanofluid on wettability and IFT changes: Experimental study for EOR applications

The application of nanoparticles(NPs) in enhanced oil recovery(EOR) offers a practical approach to resolving some surface-related problems encountered in contemporary technological processes. In this study, graphene oxide nanosheets(GONs) were synthesized by Hummer's method and, then, were subjected to surface modification by hexamethyldisilazane(HMDS) and diazonium sulfonic(DS) compounds. The new combination was known as GO-Su-HMDS. The potential stability of GO-Su-HMDS nanofluids(NFs) was investigated using the zeta(ζ) potential test. A comparative study of the effect of the synthesized NFs on wettability alteration of the reservoir rock was performed using interfacial tension(IFT) and contact angle experiments. According to the results of this study, the contact angle decreased from the initial value of 161.(oil wet) to 35.(water wet). In addition, IFT decreased from18.45 mN/m for deionized(DI) water to 8.8 mN/m for 500 ppm GO-Su-HMDS NF. Moreover, the results of flooding experiments showed that the NPs of a GO-Su-HMDS concentration of 400 and 500 ppm could increase the oil recovery by 20% and 19%, respectively. The experimental results showed that GO-SuHMDS NFs with a concentration of 500 ppm have the best efficiency in terms of altering the wettability of the rock from oil wet to water wet. Thus, it can be said that this nanofluid can reduce the contact angle and IFT and also increase the sweeping efficiency of oil.

Novel application of PEG/SDS interaction as a wettability modifier of hydrophobic carbonate surfaces

Wettability alteration of carbonate reservoirs from oil-wet to water-wet is an important method to increase the efficiency of oil recovery. Interaction between surfactants and polymers can enhance the effectiveness of surfactants in EOR applications. In this study, the interaction of polyethylene glycol(PEG) with an ionic surfactant, sodium dodecyl sulphate(SDS),is evaluated on an oil-wet carbonate rock surface by using contact angle measurements. The results reveal that wettability alteration of carbonate rocks is achieved through PEG/SDS interaction on the rock surface above a critical aggregation concentration(CAC). The behaviour of PEG/SDS aqueous solutions is evaluated using surface and interfacial tension measurements. Furthermore, the effect of PEG and SDS concentrations and impact of electrolyte addition on PEG/SDS interaction are investigated. It is shown that electrolyte(NaCl) can effectively decrease the CAC values and accordingly initiate the wettability alteration of rocks. Moreover, in a constant SDS concentration, the addition of NaCl leads to a reduction in the contact angle, which can also be obtained by increasing the aging time, temperature and pre-adsorption of PEG on the rock surface.

Investigating the Effect of Various Nanomaterials on the Wettability of Sandstone Reservoir

Wettability is the ability of a fluid to stick to a solid surface in the presence of other immiscible fluids. Wettability alteration is crucial as it affects the amount of oil recovered from a given reservoir. The majority of enhanced oil recovery mechanisms purposefully alter the wettability of the reservoir rock from oil-wet to water-wet;to increase the amount of oil recovered from it. This study investigates the effect of various nanomaterials on the wettability, and particularly the brine phase contact angle, of a sand stone reservoir. The nanomaterials used are Magnesium/Aluminum Layered Double Hydroxide, Silica/Zirconia, and a combination of 80.0% Magnesium/Aluminum Layered Double Hydroxide (Mg/Al-LDH) and 20.0% Silica/Zirconia (Zi/Zr). The results suggest that a concentration of 4.0 g/L of Magnesium/Aluminum Layered Double Hydroxide (Mg/Al-LDH) decreases the brine phase contact angle, in the presence of oil, from 66° to 60° in 0.033 minute as opposed to Silica/Zirconia which increases the brine phase contact angle to 68° in the same time interval. The combination of both nanoparticles results in a decrease of 1.0° in the brine phase contact angle indicating that Silica/Zirconia (Zi/Zr) lowers the efficiency of Magnesium/Aluminum Layered Double Hydroxide’s adsorption to the sandstone surface.