表面活性剂驱改变了碳酸盐岩储层的润湿性

水驱开采裂缝性、油湿／混合润湿碳酸盐岩储层的效果差。正在研究用稀释表面活性剂方法增加裂缝性碳酸盐岩储层的采油量。本文研究了稀释碱．阴离子表面活性剂溶液与原油在碳酸盐矿物表面的相互作用。进行了润湿性、相态、界面张力和吸附试验。本文证实了，阴离子表面活性剂同样能够将方解石表面的润湿性变成中等润湿／水湿条件，或对于西得克萨斯原油来说，阴离子表面活性剂比阳离子表面活性剂DTAB好。     

表面活性剂驱改变了碳酸盐岩储层的润湿性

水驱开采裂缝性、油湿／混合润湿碳酸盐岩储层的效果差。正在研究用稀释表面活性剂方法增加裂缝性碳酸盐岩储层的采油量。本文研究了稀释碱．阴离子表面活性剂溶液与原油在碳酸盐矿物表面的相互作用。进行了润湿性、相态、界面张力和吸附试验。本文证实了，阴离子表面活性剂同样能够将方解石表面的润湿性变成中等润湿／水湿条件，或对于西得克萨斯原油来说，阴离子表面活性剂比阳离子表面活性剂DTAB好。     

碳酸盐岩油藏表面活性剂驱的润湿性改变

水驱后油湿性/混合润湿性的碳酸盐岩裂缝油藏的采收率很低。研究的稀释表面活性剂方法可以提高碳酸盐岩裂缝油藏的采收率。本文研究了稀释的含碱阴离子表面活性剂溶液与碳酸盐岩矿石表面原油的相互作用关系。分别做了润湿性、相行为、界面张力和吸附试验。对于西得克萨斯原油,阴离子表面活性剂将方解石表面润湿性改变为中性/水湿条件的性能要优于阳离子表面活性剂DTAB。所有的碳酸盐岩(石印灰岩、大理石、白云石、方解石)表面在阴离子表面活性剂作用下都表现出类似的润湿性改变。也识别出阴离子表面活性剂与原油间具有非常低的界面张力值(<10-2mN/m),碱的添加可以大大降低磺酸盐表面活性剂的吸附。     

十六烷基三甲基溴化铵和FC911对砂岩表面润湿性的影响

分别用十六烷基三甲基溴化铵（CTAB）和阳离子氟碳型表面活性剂FC911处理石英砂,然后用Washburn法测定处理后石英砂对水和油的接触角,研究两种阳离子表面活性剂对砂岩表面润湿性的影响。实验结果表明随着处理液CTAB浓度从0增至10000 mg/L,石英砂水相接触角由0°增至89°,再减至66°,表面从水湿变为中性润湿,再变为弱水湿。FC911浓度为10～1000 mg/L时,水相接触角由〉90°逐渐减小至89.7°;油相接触角由15.3°逐渐增至〉90°。石英砂表面由强油湿变为弱油湿后再变为中间气湿。较低浓度的FC911即可将石英砂表面转变为既疏水又疏油的中间气湿,最佳使用浓度为200 mg/L。     

十六烷基三甲基溴化铵与砂岩表面的作用

为了了解阳离子表面活性剂与砂岩表面的作用,从吸附规律、吸附层的形貌、表面润湿性、表面电性等方面研究了十六烷基三甲基溴化铵(CTAB)与砂岩表面的作用。结果表明,砂岩表面的初始润湿性对它们之间的相互作用有一定的影响。亲水表面的吸附量略小于亲油表面的吸附量;在原子力显微镜下,亲水表面的吸附层为双层吸附,各层为“城墙”状,亲油表面的吸附层分层不明显;CTAB可以改变砂岩表面的润湿性,使亲水表面变为中性,亲油表面变为亲水表面;初始状态下,亲水砂岩和亲油砂岩表面均带负电,用CTAB处理后,砂岩表面的负电性减弱,高浓度的CTAB处理时砂岩表面带正电。因此,阳离子表面活性剂与砂岩表面的相互作用是不可忽视的。     

阴离子双子表面活性剂在油砂上吸附规律研究

利用静态吸附实验法研究了阴离子双子表面活性剂-双烷基乙氧基二硫酸酯钠盐在油砂上的吸附规律。实验结果表明双十二烷基乙氧基二硫酸酯钠盐(GA12-2-12)在油砂上的吸附等温线服从Langmuir等温方程,相同浓度下其吸附量低于常规单链表面活性剂-十二烷基硫酸钠(SDS)。GA12-2-12在油砂上的吸附量随着电解质浓度增大、介质pH值下降、油砂含油量降低而增大。烷基疏水链碳数及间隔基团碳数增加,双烷基乙氧/丁氧基二硫酸酯钠盐在油砂上的吸附量增大。     

脂肪醇醚磺酸盐和壬基酚醚表面活性剂的吸附性能研究

为研究驱油体系中阴离子-非离子表面活性剂在砂岩表面的吸附滞留问题,分别利用两相滴定法和硫氰酸钴盐比色法研究了非离子表面活性剂TX-10和非离子改性的阴非离子磺酸盐表面活性剂C16EOS在砂岩上的静态吸附性能,并讨论了温度、盐对吸附性能的影响。结果表明同样温度下C16EOS的吸附量高于TX-10,温度上升,吸附量下降;1% CaCl2电解质的加入,使C16EOS和TX-10的吸附量分别增加1.20mg/g和1.06mg/g;等质量浓度混合的表面活性剂体系中C16EOS和TX-10的吸附量均比单一表面活性剂低,65℃时,单一表面活性剂C16EOS和TX-10的吸附量分别为7.87mg/g和7.59mg/g,而混合体系中吸附量则为6.76mg/g和6.48mg/g,说明加入非离子表面活性剂会大幅降低醇醚磺酸盐在砂岩表面的吸附。     

表面活性剂提高致密油藏渗吸采收率研究

为了明确表面活性剂改变岩石润湿性及降低界面张力的特性对致密油藏渗吸采油的作用效果,获得表面活性剂渗吸采油的有利条件,通过测量岩心接触角和表面活性剂溶液与油间的界面张力,研究了3 种常用表面活性剂重烷基苯石油磺酸盐（ZPS）、十二烷基苯磺酸盐（SDBS）和磺基甜菜碱（SB）对致密岩心渗吸采收率的影响,分析了自发渗吸机理。结果表明,阴离子表面活性剂改变岩心润湿性的能力好于非离子表面活性剂,两种阴离子表面活性剂（ZPS、SDBS）将岩心表面由油湿反转为水湿,非离子表面活性剂（SB）降低了岩心表面接触角,但未达到润湿反转的效果;油湿岩心介质在注入水溶液中不发生渗吸,表面活性剂引起的接触角改变可实现油湿岩心渗吸采油;岩心原始润湿性影响渗吸采收率,渗吸采收率增幅从大到小依次为水湿岩心>中性岩心>油湿岩心;三种表面活性剂均可使界面张力降至最佳渗吸界面张力范围10^-1～10^-2mN/m,油水界面张力的降低有利于提高岩心自发渗吸采收率。图1 表1 参12     

单、双、三联季铵盐型表面活性剂的润湿反转能力

研究了三联季铵盐型阳离子表面活性剂(3RQ)、双联季铵盐型阳离子表面活性剂(2RQ)和单联阳离子表面活性剂(CTAB)在亲油表面上的润湿反转性能和吸附性能。油/液/固三相接触角实验结果表明,将亲油表面润湿反转为中间润湿状态(接触角90°左右)的过程中,3RQ的浓度为2.17×10-3mmol/L,比2RQ(0.016 mmol/L)和CTAB(0.27 mmol/L)的浓度分别低了1数2个数量级;同时,3RQ、2RQ和CTAB获得稳定接触角的时间分别为20 min、35 min和35 min。此外,中间润湿状态浓度下,3RQ在亲油云母片上的吸附是连续的片状分布;而CTAB和2RQ分别是点状分布和带状分布。中间润湿状态浓度下,3RQ在油砂上的吸附更加彻底。三种表面活性剂润湿反转的能力与它们在亲油表面上的吸附能力相关。     

双子表面活性剂在石英砂上的吸附规律研究

利用亚甲蓝法,测量双子表面活性剂与普通阳离子表面活性剂CTAB在石英砂上的吸附等温线.结果表明:双子表面活性剂的联接基长度对其在石英砂表面上的吸附具有很大的影响;疏水烷基链长度同样影响饱和吸附量,但是影响较小;另外,相同疏水烷基链长度的阳离子双子表面活性剂在石英砂表面上的饱和吸附量接近普通阳高子表面活性剂CTAB在石英...     

CTAB改变固体表面润湿性的机理探讨

为了解阳离子表面活性剂改变固体表面润湿性的机理,首先用washburn法和微观实验研究了十六烷基三甲基溴化铵（CTAB）对润湿性的影响,然后从吸附状态及化学反应的角度分析了CTAB与砂岩表面的作用机理。研究结果表明,砂岩表面的初始润湿性对它们之间的相互作用有一定的影响,CTAB可以改变砂岩表面的润湿性,使亲水表面变为中性,亲油表面变为亲水表面;在原子力显微镜下,亲水表面的吸附层为双层吸附,各层为“城墙”状,亲油表面的吸附层分层不明显;CTAB与带负电的砂岩表面可以发生化学作用而改变润湿性,还可以通过剥离砂岩表面的油膜而改变润湿性。     

Wetting alteration of mica surfaces with polyethoxylated amine surfactants

Characterization of reservoir wettability is an important part of assessment of potential oil recovery. Oil-based drilling fluids include surfactants, which can alter the wettability of mineral surfaces. Cores exposed to these fluids may not reflect the true wettability of the reservoir materials.The focus of this study was to observe wettability changes induced by adsorption and removal of surfactants of known structure on mica surfaces using tools that are applicable to studies of wetting alteration by crude oil components. The surfactants used were polyethoxylated coconut and tallow amines with chain lengths of 12 and 18 carbons and head groups consisting of two to five ethoxy groups. Mica was exposed to decane solutions of the surfactants. The treated mica was characterized macroscopically using contact angle measurements and microscopically using atomic force microscopy (AFM).Upon exposure to the surfactant solutions, the mica became oil-wet ( 170° for both advancing and receding conditions). AFM examination of similarly treated surfaces imaged in air revealed surfactant layers that were easily disrupted or surfaces that showed no surfactant at all. Contact angles were in the intermediate to water-wet range if the mica samples were removed from the surfactant solution, rinsed with non-aqueous solvents, and submerged in decane for measurements of water/decane contact angles. These results suggest only weak surfactant adsorption occurred from non-aqueous solutions. Differences among the structures tested were greater for increased levels of ethoxylation; differences due to hydrocarbon chain length were negligible. Stronger adsorption, higher contact angles, and more stable surfactant layers could be demonstrated when mica was exposed to aqueous solutions after surfactant sorption, depending on the pH of the aqueous phase. Low pH conditions that promote protonation of the surfactants' amine head group produced the greatest wetting alteration. Above a pH of 8 or 9, no surfactant remained adsorbed on mica surfaces.     

改善岩芯润湿性能微乳剂的研制

通过紫外-可见分光光度法研究阳离子与非离子表面活性剂与岩芯间的吸附规律,研制出一种能改善岩芯润湿性能的微乳剂。研究表明Gemini型阳离子表面活性剂吸附在亲水岩芯表面发生润湿反转;非离子型表面活性剂处理后岩芯仍保持亲水的润湿状况;二者以不同比例复配后,共同吸附在岩芯表面使岩芯呈现出不同的润湿性;与一定量助剂复配形成的微乳剂能够改善亲水岩芯的润湿状况为中性-弱亲水,明显降低工作液的表面张力,有助于工作液的返排,使地层免受工作液的伤害,达到油气井增产稳定的效果。     

Wettability Alteration of Low-permeable Carbonate Reservoir Rocks in Presence of Mixed Ionic Surfactants

Abstract

Altering the wettability of the carbonate reservoir rocks from oil-wet to water-wet has figured prominently as one of the enhanced oil recovery methods in recent years. The authors measured the effect of different ionic surfactants on the wettability alteration of the rock, saturated with crude oil, and the consequent improvement in oil production was investigated by spontaneous imbibitions of solutions containing cationic, anionic, and cationic-anionic surfactant mixtures. A very low-permeable carbonate rock from one of the Iranian oil reservoirs was selected for this study. The results of imbibition tests were furthermore supported by measuring IFT, taking pictures of producing oil drops from different exterior core plug surfaces and also observing the distribution of the remaining oil in cores at the end of experiments. The results show that cationic surfactants at concentrations higher than CMC can cause a remarkable oil production through alteration of wettability and, moreover, the extent of oil production increases with temperature. In contrast, it is observed that the anionic surfactants are not able to change the wettability of an oil-wet surface and their combination with the cationic type would reduce the oil production potential of cationic surfactants.     

Impacts of Wettability on Immiscible Fluid Flow Pattern-Microfluidic Chip Experiment

Immiscible fluid flow is frequently found in resource recovery or soil remediation. The flow pattern in the porous media is affected by the wettability of pore surface. In this study, quartz substrates and microfluidic chips are treated by silica nanoparticles(SNP) and triethoxy(octyl)silane(TES) to fabricate the water-wet and oil-wet surfaces. The wettability of the treated-surface is measured in term of contact angle for several combinations of surrounding fluid and a liquid droplet. The effect of the wettability on the fluid flow pattern is explored by injecting oil and water alternately into the surface-treated microfluidic chips. The results reveal that the SNP-coated quartz substrate shows strong water-wet property and the TES coating makes water-repellent/oil-wet surfaces. In addition, it is found that the maximum and minimum oil and water saturation during alternate injection of oil and water depends on the surface wettability of the microfluidic chips. The characteristics of the pore-scale fluid flow pattern are also described.     

油湿灰岩储层中季胺类物质对周期注水开发效果的影响

周期注水是开发灰岩储层低渗透基质中原油的一种有效方法,但对于亲油储层效果较差。对基质含水饱和度变化特征进行了分析,建立了基质含水饱和度变化特征方程,提出了周期注水与润湿反转技术相结合的开采方式。利用油湿灰岩裂缝模型,在注入水中加入低浓度具有润湿反转能力的季胺类物质——十六烷基三甲基溴化铵(CTAB)进行了周期注水室内模拟研究。结果表明,CTAB可使油湿灰岩储层的表面性质发生明显变化,基质毛管的自吸及滞水排油能力增强,周期注水开发效果明显改善。     

VISCOSITY OF WATER-OIL EMULSIONS WITH ADDED NANO-SIZE PARTICLES

The viscosity of emulsion and suspensions in the presence of two types of nano-size particles that, have different affinity for oil, have been investigated. It has been found out that both oil-solid suspensions and oil-water-solid mixtures behave as pseudoplastic fluids at all studied solid concentrations. The viscosity of emulsion-solid mixtures does not seem to get affected by water concentration, yet it is a function of solid concentration.

The ability of solids to act as emulsifying agents has also been investigated. It has been established that neither of the two types of solids used is capable of stabilizing water-in-oil or oil-in-water emulsions in the absence of surfactants. At low concentrations of solids and in the presence of an oil-soluble surfactant, both oil-wet and water-wet solids, however, are capable of stabilizing water-in-oil emulsions. In the presence of water-soluble surfactant, only water-wet solids are capable of stabilizing oil-in-water emulsions.     

润湿性对采收率及相对渗透率的影响

通过实验研究了润湿性对采收率及相对渗透率的影响,还研究了利用原油老化控制岩石润湿性的方法。结果表明弱水湿岩石水驱采收率最高,亲水岩石油相相对渗透率高于亲油岩石,原油中极性物质的吸附会影响岩石表面润湿性,油湿性随老化时间增加而增强。     

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.     

Beneficial effects of wettability altering surfactants in oil-wet fractured reservoirs

In fractured reservoirs, an effective matrix-fracture mass transfer is required for oil recovery. Surfactants have long been considered for oil recovery enhancement, mainly in terms of their ability to reduce oil–water interfacial tension. These surfactants are effective when the fractured formations are water-wet, where capillary imbibition of surfactants from the fracture into the matrix contributes to oil recovery. However, another beneficial aspect of surfactants, namely their ability to alter wettability, remains to be explored and exploited. Surfactants capable of altering wettability can be especially beneficial in oil-wet fractured formations, where the surfactant in the fracture diffuses into the matrix and alters the wettability, enabling imbibition of even more surfactant into the matrix. This sequential process of initial diffusion followed by imbibition continues well into the matrix yielding significant enhancements in oil recovery.In order to test this hypothesis of sequential diffusion–imbibition phenomenon, Dual-Drop Dual-Crystal (DDDC) contact angle experiments have been conducted using fractured Yates dolomite reservoir fluids, two types of surfactants (nonionic and anionic) and dolomite rock substrates. A new experimental procedure was developed in which crude oil equilibrated with reservoir brine has been exposed to surfactant to simulate the matrix-fracture interactions in fractured reservoirs. This procedure enables the measurements of dynamic contact angles and oil–water interfacial tensions, in addition to providing the visual observations of the dynamic behavior of crude oil trapped in the rock matrix as it encounters the diffusing surfactant from the fractures. Both the measurements and visual observations indicate wettability alterations of the matrix surface from oil-wet to less oil-wet or intermediate wet by the surfactants. Thus this study is of practical importance to oil-wet fractured formations where surfactant-induced wettability alterations can result in significant oil recovery enhancements. In addition, this study has also identified the need to include contact angle term in the dimensionless Bond number formulations for better quantitative interpretation of rock–fluids interactions.