鼠李糖脂作为牺牲剂对大庆油田三元复合体系抗吸附性能及驱油效果的评价

强碱三元复合驱技术广泛应用于大庆油田,随着国际原油价格持续走低,降低开采成本成为迫在眉睫的技术难题。为此,研究在三元复合体系中加入适量的廉价牺牲剂,以减少高成本表面活性剂在地层油砂中的吸附损失,进一步提高驱油效率。以生物表面活性剂鼠李糖脂为研究对象,分别采用复配及预吸附的方法,对其改变岩石润湿性、抗吸附及驱油性能进行评价。实验结果表明,鼠李糖脂与烷基苯磺酸盐复配后,二者之间存在着明显的协同效应;鼠李糖脂及其代谢产物可以有效地改变岩石的润湿性,相对润湿指数均由弱亲油性向弱亲水性方向移动;鼠李糖脂可有效降低表面活性剂和碱的吸附损失,可降低表面活性剂吸附损失9.4个百分点,Na OH可减少吸附损失9.8个百分点;在等黏度的驱油条件下,前置段塞注入方式优于复配混合注入方式,前者可使总采收率提高近5个百分点。     

表面活性剂复配在三次采油中的应用

表面活性剂是制约三次采油技术发展的关键因素。将油水界面张力降低到10-3mN/m数量级、在岩石上吸附量小、与电解质和聚合物配伍性好、热稳定性和水溶液的化学稳定性好、成本低,是高效驱油用表面活性剂的发展方向。不同表面活性剂复配可产生协同增效作用,可提高表面活性剂体系的性能和对不同油水条件的适应性,降低表面活性剂用量和成本,提高复合驱的经济性。表面活性剂复配时应注意:①阳离子表面活性剂易与带负电的油层和聚丙烯酰胺等聚合物发生电中和作用,而造成吸附损失和沉淀损失,因此阳离子表面活性剂的选择和使用应慎重;②避免复配体系中各表面活性剂在应用中出现色谱分离;③同类表面活性剂复配协同效应小,但可弥补单一表面活性剂性能的不足。适合弱碱和无碱的表面活性剂复配体系以及生物表面活性剂是未来表面活性剂复配技术的研发方向。     

二元体系中化学剂浓度对驱油效果的影响

表面活性剂/聚合物二元体系可以最大限度地发挥聚合物的黏弹性并具有较低的界面张力。在成本相同的情况下,二元复合物驱可达到与三元复合驱相同的驱油效果,同时减少了乳化液的负面影响,避免了由于碱的存在引起的地层及井的结垢现象。通过室内物理模拟实验,研究了非均质岩心条件下表面活性剂浓度、聚合物浓度对二元体系驱油效果的影响。实验结果表明:二元复合驱采收率可比水驱提高20%左右;随着聚合物浓度的增加,二元体系驱油效率增加;在二元体系黏度较高的条件下,随着表面活性剂浓度的降低,二元体系的驱油效率不会出现显著下降;对于非均质岩心,在较高聚合物用量条件下,可以弥补由于表面活性剂浓度的降低使二元体系油水界面张力上升而导致的体系驱油效率的下降,并在一定程度上可以降低表面活性剂的用量。     

生物质活性炭对亚甲基蓝的吸附平衡和动力学研究

利用玉米芯为原料制备的活性炭吸附水相中不同浓度的亚甲基蓝溶液,亚甲基蓝的初始浓度为50～250mg/L。试验条件:吸附时间为1～48h、亚甲基蓝的初始浓度为50～250mg/L、温度为30℃,得到了玉米芯活性炭吸附亚甲基蓝的吸附等温线和吸附动力学曲线。试验结果表明:Freun-dlich吸附等温线模型能够比较准确地描述亚甲基蓝在玉米芯活性炭上的吸附相平衡;准二级反应模型更准确地描述玉米芯活性炭的吸附过程;平衡时活性炭的吸附能力为48.5～225mg/g。由此可知,玉米芯活性炭对去除水溶液中的亚甲基蓝染料效果佳,是一种具有发展潜力的吸附剂。     

铀在放射性废物处置场周边土壤中的吸附行为及机理研究

放射性核元素在土壤介质中的吸附特征是放射性废物处置场地选址及安全评价中最重要的考虑因素之一。为探讨核素铀在放射性废物处置场预选场址周边土壤介质中的吸附行为与机理,实验以深圳市蛇山顶(SSD)及阳江市大尖山(YJ)表层土壤为研究对象,采用批式实验法研究不同铀初始质量浓度及离子强度对其吸附核素铀行为的影响,并通过吸附动力学模型及吸附等温线模型对实验数据进行拟合,分析吸附机理。结果表明:当铀初始质量浓度增大时,SSD及YJ土壤对U(VI)的平衡吸附量也增大,但去除率则分别从97.07%、91.56%下降至88.55%、87.93%;离子强度对SSD土壤吸附U(VI)的影响并不显著,表明U(VI)在SSD土壤上的吸附可能以内层络合反应为主;准二级动力学方程及Langmuir吸附等温模型能够很好地拟合吸附动力学及平衡吸附实验结果,相关系数R2均在0.99以上。实验获取的这些参数为核素铀在土壤介质上的吸附模型的建立提供了重要依据,且为推测核素铀在环境中的迁移行为提供了研究基础。     

硅片表面织构对PERC单晶硅太阳电池电性能影响的研究

通过调整制绒腐蚀液添加剂中表面活性剂和成核剂的添加比例,制备出不同表面织构的硅片,研究了表面活性剂和成核剂的添加比例对硅片表面微观形貌和反射率,以及PERC单晶硅太阳电池电性能的影响规律。结果表明：随着表面活性剂添加比例的增加,腐蚀液对硅片的清洗效果逐渐增强,存在黑斑、麻点及脏污的太阳电池的占比逐渐减少;同时,单晶硅片表面形成的金字塔尺寸(宽度)逐渐减小,比表面积先增大后减小,从而导致太阳电池的光电转换效率呈现先升高再降低的规律;当表面活性剂的添加比例为0.6%时,太阳电池的光电转换效率达到最大值,为22.736%。随着成核剂添加比例的增加,单晶硅片绒面金字塔的均匀性逐渐提升,当成核剂的添加比例大于0.8%时,绒面金字塔的均匀性基本稳定,太阳电池的光电转换效率也达到最大值,为22.784%。     

耐温抗盐泡沫驱油体系的构建及性能研究

为了改善高温、高盐油藏泡沫驱油体系性能,揭示泡沫性能与发泡液表面性质的关系,针对现场使用的单一表面活性剂(原体系)进行复配优化,并研究泡沫性能与表面张力、表面扩张模量的关系。通过单一发泡剂性能考察、发泡剂复配以及助剂优选,确定复配体系配方为0.105%(质量分数)CHSB+0.045%(质量分数)AES+150mg/L十四醇。研究结果表明,复配体系发挥了协同增效作用,较原体系的泡沫体积、泡沫半衰期以及综合指数分别提高了27%、109%和165%。原体系的发泡性能受表面张力的控制,泡沫稳定性受表面张力和表面扩张模量两个因素的影响。复配体系的发泡性能受表面张力的控制,当发泡剂浓度较低时,泡沫稳定性与表面张力呈负相关;当发泡剂浓度较高时,泡沫稳定性与表面扩张模量呈正相关。研究结果为构建耐温抗盐泡沫驱油体系提供了依据。     

纳米流体导热系数的影响因素分析

采用"两步法"制备质量分数为0.5%、1.0%、2.0%和4.0%的Cu-乙二醇纳米流体,添加了聚乙烯吡咯烷酮(PVP)和十二烷基苯磺酸钠(SDS)作为表明活性剂。利用Hot Disk 2500s热常数分析仪测试Cu-乙二醇纳米流体导热系数,在分析温度和颗粒浓度对其导热系数的影响基础上,重点研究了两种不同表面活性剂及添加量对纳米流体导热系数的影响。结果表明:Cu-乙二醇纳米流体的导热系数随质量分数的增大而增大,随温度的升高而增大。添加了PVP的纳米流体导热系数随PVP的添加量增加呈先增加后减小的趋势,但添加了SDS的纳米流体的导热系数小于无表明活性剂时纳米流体导热系数。适当的纳米颗粒浓度与PVP表面活性剂浓度比例,对提高Cu-乙二醇纳米流体的导热系数有帮助。     

氨水活化活性炭用于CH_4和CO_2的分离研究

采用不同浓度的氨水作为活化剂制备活性炭,引入含氮官能团以提高活性炭对CO2的吸附能力和CO2/CH4吸附选择性。对活性炭的孔结构和表面化学性质进行了表征,活性炭的表面化学性质分别通过傅里叶变换红外光谱、酸碱滴定和X射线光电子能谱等方法进行表征,并测定了活性炭对CO2和CH4的吸附等温线。结果显示,与纯水活化活性炭相比,采用氨水活化制备活性炭增加了表面含氮官能团,主要是吡啶类、胺或腈类基团的数量,同时减少了含氧官能团的数量。这些基团使得活性炭表面具有更强的碱性,从而使氨水活化活性炭具有更强的CO2吸附能力和CO2/CH4吸附选择性。     

我国油砂开采技术的进展

<正>中国石油勘探开发研究院针对我国各地油砂的特点,提出了适用于不同性质油砂的不同的分离方法,建立了水洗法、干馏法、溶剂法工艺流程,摸索出适合我国西北油砂特点的有效分离方法——干馏法,并研制出有独立知识产权的干馏装置,2005年在准噶尔盆地进行了现场试验,效果良好。干馏法适合水分含量低、含油率6%以上的油砂,出油率达到80%以上。目前,已完成日处理200t油砂的第二代高效立式干馏炉及水平旋转干馏炉的设计。水洗法适合含油率大于6%     

杏北油田三元配注工艺适应性研究

三元复合驱油技术已成为三次采油的主要技术,但三元复合驱配注工艺如何适应油田开发需求,已成为其工业化推广的关键所在.杏北油田经过大量的技术研究与现场试验,探索出“低压一元、高压二元”、管混式“低压三元、高压二元”、罐混式“低压三元、高压二元”三种配注工艺,同时结合开发需求,对上述工艺从技术指标、生产管理及建设投资等方面进行对比分析,总结出各种配注工艺的特点.现场运行跟踪分析显示,“低压一元、高压二元”配注工艺有适用范围的限制,虽然注入体系中黏度和界面张力的合格率均能达到90％以上,但碱、表面活性剂的浓度波动范围较大;应用动态混合器混配低压三元的管混式“低压三元、高压二元”配注工艺,能够较好地满足开发要求;罐混式“低压三元、高压二元”配注工艺对自控系统及泵阀的连锁要求高,受自控系统的制约,系统存在一定波动.     

大庆三次采油用表面活性剂技术现状及发展方向

目前大庆油田三元复合驱的主导技术是能大幅降低油水界面张力及成本的强碱三元复合驱,其主表面活性剂是重烷基苯磺酸盐表面活性剂,在试验区应用后,中心井采出程度24.79%,阶段提高采收率20.3%;石油磺酸盐和石油羧酸盐的技术虽然仍不成熟,但由于原料来源充足,产品价格低廉,极具发展空间。强碱复合驱的使用带来了现场施工工艺复杂、油藏及井底结垢、生产井产液能力下降、检泵周期缩短以及采出液破乳脱水困难等问题,严重制约着复合驱技术的进一步应用,因此,弱碱化甚至无碱化是三元复合驱技术发展的必然趋势。弱碱三元复合驱包括弱碱烷基苯磺酸盐、石油磺酸盐和烷基苯磺酸盐复配、烷基苯磺酸盐与生物表面活性剂复配;无碱二元驱技术中有望实现无碱化的有烷基芳基磺酸盐、Bola型表面活性剂、Gemini表面活性剂、甜菜碱系两性表面活性剂等。     

Using a model to predict the migration and transformation of chemicals for alkali-surfactant-polymer flooding in soil

In recent years, alkali–surfactant–polymer (ASP) flooding has been widely used in Daqing area. In order to predict the possible impact of leakage accident, this paper not only established a corresponding model to predict the migration of various components of ASP flooding in soil but also calculated the kinetic parameters of the equation and obtained the vertical migration rule of pollutants in the soil through comparative analysis.     

Experimental studies of ionic surfactant adsorption onto carbonate rocks

One of the main factors in chemical-based enhanced oil recovery, especially surfactant flooding, is a surfactant adsorption loss onto the reservoir rock. The main aim of this article is performing systematically a study on the adsorption behavior of an industrial ionic surfactant, which is currently employed in petroleum upstream. It is worth mentioning that sodium dodecyle sulphate was employed as an ionic surfactant in this study. Moreover, adsorption density at equilibrium condition was determined. Crushed carbonate rocks were used as rock samples. To determine adsorption behavior of the aforementioned surfactant onto carbonate surface, various surfactant concentrations were created in the range of 500 to 5,000 ppm. Furthermore, via using an electrical conductivity measurement, the surfactant concentration in each solution before and after contacting with carbonate rocks was determined. Two well-known adsorption isotherms, including Freundlich and Langmuir, were employed to specify the adsorption mechanism. Based on the experimental results the Freundlich adsorption isotherm can predict the adsorption behavior of SDS onto carbonate rock surface.     

Sensitivity analysis and optimization on effective parameters during chemical enhanced oil recovery (CEOR) using experimental design and numerical simulation

Several factors effect on choosing the best enhanced oil recovery process in a hydrocarbon reservoir. In the present study, effective factors on chemical enhanced oil recovery involved in polymer flooding, surfactant flooding, surfactant–polymer flooding, and alkaline–surfactant–polymer flooding are discussed in numerical simulation. The numbers of the simulation runs are estimated based on the number of factors and their maximum and minimum values using experimental design software. Oil recovery factor from reservoir simulation is considered as comparison factor in all of the run cases. The results from one parameter and two interaction factors during each flooding case were analyzed by Tornado and Parto plot. The oil recovery factor also was estimated using statistical analysis using Minitab. The results show that there is a strong correlation between simulation and statistical analysis. Furthermore, the results show that each selected factor has a different effect on oil recovery in each case of chemical flooding. The case study results on two Iranian oil fields at the end of the present study clarified that results of this study can be useful for selecting the best chemical process for oil reservoir based on reservoir properties.     

Effects of weak-alkali ASP composition on the stability of O/W emulsions

The effects of weak-alkali ASP composition on the o/w emulsion-stabilizing properties of simulative produced liquid by the weak-alkali ASP flooding were analyzed by use of spinning-drop interfacial-tension (IFT) meters, microscopes, zeta-potential analyzer and Turbiscan laboratory expert stabilizer in this work. The experimental results showed that the irregular movement of the droplets in the lower and middle regions is the main cause of the instability of the emulsion system. The addition of alkali changes the movement of emulsion droplets formed by the weak-alkali ASP system and the oil. Both weak-alkali and surfactants play dual roles in the ASP system. The optimum amount can make the emulsion achieve the best stability and less or more amounts are not conducive to the stability of the emulsion. Appropriately increasing the polymer concentration is helpful to increase the stability of the emulsion. However, the addition of an excessively high concentration of polymer does not increase the stability of the emulsion, resulting in unnecessary waste. It is expected that this study will be of guiding significance for the mechanism of weak-alkali ASP flooding and the treatment of produced liquid in actual production.     

Dynamic Interfacial Tension between Crude Oil and Dodecylmethylnaphthalene Sulfonate Surfactant Flooding Systems

Abstract

The surface tension of surfactant aqueous solutions and dynamic interfacial tensions (DIT) between crude oil, offered from Shengli Oil Field in China, and surfactant flooding systems, and the single-component dodecylmethylnaphthalene sulfonate (DMNS) surfactant, developed in our laboratory, were measured. In the present report, both buffered alkali and no alkali flooding systems were investigated. It was found that DMNS surfactant possessed great capability and efficiency of lowering the solution surface tension and the critical micelle concentration (cmc) is 0.002 mass% and the surface tension at this concentration is 29.39 mN.m^?1. It was also found that the DMNS surfactant is also greatly effective in reducing the interfacial tensions and can lower the tension of crude oil-water interface to ultra-low at very low surfactant concentration and an optimum range of sodium chloride. The lower alkali concentration is favorable for lowering DIT. The higher alkali concentration needs a higher surfactant concentration for oil flooding systems lowering DIT. Moreover, the results indicate that there obviously exists both synergism and antagonism among the surfactant, alkali and inorganic salt. The added surfactant play an important role in reducing DIT, and the prepared DMNS surfactant possesses great capability and efficiency in lowering the interfacial tension between oil and water. The salt-modified surfactant flooding systems without alkali, decreasing the cost of oil recovery and avoiding the stratum being destroyed would have a great prospect for enhanced oil recovery.     

适合大庆油田的无碱表面活性剂性能评价研究

随着油田不断开发,大庆油田开发对象正逐渐从一类油层向渗透率低、黏土矿物含量较高的二、三类油层转变,但逐步进入工业化推广阶段的三元复合驱中碱的存在会加剧对二、三类油层的伤害,因此弱碱化、无碱化成为了复合驱技术的发展方向.针对大庆油田二类油层油水条件,采用AFS-A和AFS-B无碱表面活性剂复合体系开展了二元复合驱室内研究.实验结果表明:这两种无碱表面活性剂复合体系均可在活性剂浓度为0.05％～0.3％(质量分数)范围内与大庆原油形成10-3,N/m数量级界面张力,但AFS-B复合体系亲水性较强,AFS-A复合体系亲油性较强,AFS-B复合体系抗吸附性能要好于AFS-A复合体系;驱油效率方面,在水驱基础上,AFS-A复合体系化学驱平均采收率为17.28％,AFS-B复合体系化学驱平均采收率为19.81％.     

Adsorption of a nonionic surfactant onto a silica surface

Chemical flooding is technically feasible to increase oil recovery from depleted sandstone reservoirs with low pressure. Polymer-surfactant flooding is a potential process in the chemical flooding methods for enhanced oil recovery (EOR) in sandstone porous media. However, chemical additive cost and surfactant loss due to adsorption on the reservoir rock are the main concerns in this type of EOR processes. This paper presents adsorption equilibrium of a natural surfactant, Zyziphus spina-christi, onto a real sandstone reservoir. Batch adsorption experiments were carried out to figure out the impacts of adsorbent dose on adsorption performance. The equilibrium adsorption data were analyzed with two common adsorption models and it was found that the Freundlich model is a pretty good fit for adsorption equilibrium of Z. spina-christi based on the value of determination coefficient (R²). Results from this study are instructive for appropriate selection of surfactants in design of EOR processes and reservoir stimulation plans for sandstone reservoirs.