Dynamic Interfacial Tension Between Crude Oil and Novel Surfactant Flooding Systems Without Alkali

The surface tensions of tetradecylmethylnaphthalene sulfonate (TMNS) surfactant aqueous solution and the dynamic interfacial tension (DIT) between crude oil, from Shandong Shengli oil field of China, and the surfactant solution without alkaline, was measured. Results indicate that the TMNS surfactant had great capability and efficiency of lowering the solution surface tension. The critical micelle concentration (cmc) is 0.001 mass% and the surface tension at this concentration is 28.19 mN.m^-1. It was also found that the TMNS surfactant is greatly effective in reducing the interfacial tensions and can lower the tension of crude oil-water interface to ultra-low at very low concentration, 0.002 mass%, without alkali and other additives. Both chromatogram separation of flooding and breakage of stratum are avoided effectively. The lower salinity is favorable for the flooding systems, lowering the DIT. The synthesized TMNS surfactant flooding systems without alkali and sodium chloride, decreasing the cost of oil recovery and avoiding the stratum being destroyed, would have a great prospect for enhanced oil recovery (EOR).     

STUDYING THE INTERACTIONS BETWEEN AN ARABIAN HEAVY CRUDE OIL AND ALKALINE SOLUTIONS

An experimental study to examine the effectiveness of alkaline flooding for the recovery of an Arabian heavy crude oil is presented. The interfacial tension (IFT) behavior of crude oil/alkali systems over a wide range of parameters (pressure, temperature, alkali concentration and time) was studied. These alkaline reagents react with the acidic species in crude oil to form surface-active soaps in-situ. This leads to a lowering of interfacial tension (IFT) and subsequently the mobilization of residual oil. The equilibrium IFTs obtained through alkaline flooding are compared with the IFTs when a synthetic surfactant (dodecyl benzene sulfonic acid sodium salt) is used in EOR recovery. A mathematical model representing the complete chemistry of the transient process is also presented. The model consists of a set of differential equations describing reactions, diffusion, and adsorption at the oil/alkaline solution interface. The kinetic parameters in the model are obtained through a differential algebraic optimization technique. The concentration of the surface active species are related to the measured IFTs through an independent step that is based on isolating the surface active species formed by the reaction between the acids in the crude oil and the alkaline solution. A sensitivity analysis using the model is carried out to study the effect of surface potential and alkaline concentration on the transient interfacial tensions.     

STUDYING THE INTERACTIONS BETWEEN AN ARABIAN HEAVY CRUDE OIL AND ALKALINE SOLUTIONS

ABSTRACT

An experimental study to examine the effectiveness of alkaline flooding for the recovery of an Arabian heavy crude oil is presented. The interfacial tension (IFT) behavior of crude oil/alkali systems over a wide range of parameters (pressure, temperature, alkali concentration and time) was studied. These alkaline reagents react with the acidic species in crude oil to form surface-active soaps in-situ. This leads to a lowering of interfacial tension (IFT) and subsequently the mobilization of residual oil. The equilibrium IFTs obtained through alkaline flooding are compared with the IFTs when a synthetic surfactant (dodecyl benzene sulfonic acid sodium salt) is used in EOR recovery. A mathematical model representing the complete chemistry of the transient process is also presented. The model consists of a set of differential equations describing reactions, diffusion, and adsorption at the oil/alkaline solution interface. The kinetic parameters in the model are obtained through a differential algebraic optimization technique. The concentration of the surface active species are related to the measured IFTs through an independent step that is based on isolating the surface active species formed by the reaction between the acids in the crude oil and the alkaline solution. A sensitivity analysis using the model is carried out to study the effect of surface potential and alkaline concentration on the transient interfacial tensions.     

Synthesis and Interfacial Behavior of Decyl Methylnaphthalene Sulfonate

Abstract

High purity decyl methylnaphthalene sulfonate (DMNS) surfactant was synthesized. The purity of product was determined by HPLC, and the structure was confirmed by IR, UV, and ESI-MS. The surface and oil-water interfacial activities of DMNS surfactant were studied. The effects of concentrations of the surfactant, alkali, and inorganic salt on the dynamic interfacial behavior of crude oil/Shengli Oil Field/surfactant oil flooding systems were studied, and comparitive studies of systems with strong and buffered alkali were also carried out. Results showed that DMNS surfactant possessed great capability and efficiency for lowering solution surface tension and oil-water interfacial tension. The critical micelle concentration (cmc) was 0.02% and the surface tension at this concentration was 31.61 mN.m^?1. At proper concentrations of the surfactant, alkali, and inorganic salt, the dynamic interfacial tension between the crude oil of the Shengli Oil Field and the surfactant oil flooding system reached a minimum value of 10^?5–10^?6 mN.m^?1 in a very short time (3–20 min) and maintained an ultra-low value (< 10^?2 mN.m^?1) for a long period of time (15–87 min). The crude oil/surfactant systems presented satisfactory interfacial behavior. DMNS has great potential to be used in enhanced oil recovery (EOR) with low cost and high efficiency.     

Interfacial tensions of phenyltetradecane sulfonates for enhanced oil recovery upon the addition of fatty acids

Producing ultra-low interfacial tensions is one of the most important mechanisms relating to surfactant flooding for enhanced oil recovery. Most crude oils contain organic acids, so it is of great significance to study the effects of fatty acids on the interfacial tensions of surfactant systems. The dynamic interfacial tension behavior of three surfactant systems, 1-phenyltetradecane sulfonate (1-PTDS), 3-phenyltetradecane sulfonate (3-PTDS) and 5-phenyltetradecane sulfonate (PTDS), were researched upon the addition of fatty acids to oil phase, n-octane. It has shown that the interfacial activity of surfactants and their ability of adsorption into interface control the dynamic interfacial tensions between aqueous solutions and oil phase. The interfacial tensions of 1-phenyltetradecane sulfonate decrease upon the addition of fatty acids, that of 3-phenyltetradecane sulfonate increase or do not change and that of 5-phenyltetradecane sulfonate increase. When mixed at appropriate concentrations and ratios, phenyltetradecane sulfonates and fatty acids could produce synergism for obtaining lower interfacial tensions. This study may be helpful in accounting for the cause of producing ultra-low interfacial tensions and for preparing formulations of practical application.     

Evaluation of Interfacial Tension Between SP Solution and Simsim Oil

Surfactant–polymer (SP) flooding has been proved to be an effective enhanced oil recovery method. Producing ultra-low interfacial tensions is an important mechanism relating to SP flooding for enhanced oil recovery. The interfacial tension between surfactant (PJS-1 and BE)/polymer solution and Simsim oil was evaluated in the work. The influence of surfactant and polymer concentration on interfacial tension between Simsim oil and these solutions is discussed. The interfacial tension between the oil and the surfactant solution reduces as the surfactant concentration increases. In the same concentration of surfactant, the interfacial tension between the surfactant solution and the oil becomes larger when the polymer was added in the solution.     

无碱二元体系的黏弹性和界面张力对水驱残余油的作用

三元复合驱含碱驱油体系会大幅度降低聚合物溶液的黏弹性,引起地层粘土分散和运移、形成碱垢及导致地层渗透率下降。为此提出利用不加碱可形成超低界面张力的聚合物/甜菜碱表面活性剂二元复合体系驱油。通过流变性实验及微观模型驱油实验,分析了表面活性剂对聚合物表面活性剂二元复合体系黏弹性的影响和聚合物表面活性剂二元复合体系的黏弹性及界面张力对采收率的影响。对聚合物表面活性剂二元复合体系提高水驱后残余油采收率机理的研究表明:在驱替水驱后残余油过程中,聚合物表面活性剂二元复合体系利用了聚合物溶液的黏弹特性和表面活性剂的超低张力界面特性,水驱后残余油以油丝和乳状液形式被携带和运移,随着二元驱油体系的黏弹性的增加和界面张力的降低,水驱后二元驱后的采收率增加,降低界面张力的驱油效果(指达到超低)比提高体系的黏弹性的效果更明显。     

以大庆减压渣油为原料的高效、廉价驱油表面活性剂OCS的制备与性能研究

针对现有三元复合驱油体系化学剂费用投入大，经济效益差的缺点，以廉价的大庆减压渣油为原料在实验室内合成出廉价的驱油用表面活性剂OCS，并初步评价了所得OCS样品的性能。结果表明，OCS表面活性剂制备重复性好，性能稳定。OCS表面活性剂具有优异的降低原油一地层水界面张力的能力，在NaOH存在条件下，能在较宽的碱浓度范围内使大庆四厂原油的油-水界面张力降至10^-3mN／m。在Na2CO3存在条件下，能在较宽的碱浓度范围内使大庆四厂原油、华北油田古一联原油及胜利孤东采油厂原油的油-水界面张力降至10^-3mN／m。在无碱条件下，对于大港油田枣园1256断块原油，当OCS表面活性剂含量达到0．1％时，油-水界面张力即可降至10-3^mN／m。对大庆四厂原油的驱油试验结果表明，OCS表面活性剂、碱和聚合物三元复合体系(ASP)的驱油效率比水驱提高20％以上。     

化学驱中动态界面张力行为的研究进展

汇总了近年来强化采油动态界面张力研究进展的报道,阐述了驱油过程中的动态界面张力行为,总结了碱浓度、油相粘度、驱替液粘度对原油/碱体系及原油/碱/聚合物体系动态界面张力的影响和表面活性剂、离子强度对原油/碱/表面活性剂体系及原油/碱/表面活性剂/聚合物体系动态界面张力的影响,并对上述影响因素进行了归纳。     

OCS表面活性剂工业品的界面活性及驱油效率

针对现有三元复合驱油体系化学剂费用投入大,经济效益差的缺点,利用廉价的大庆减压渣油为原料合成了驱油用表面活性剂OCS.测试结果表明,OCS表面活性剂工业品具有优异的降低原油-地层水界面张力的能力,能在较宽的碱浓度和表面活性剂浓度范围内使不同大庆采油厂原油的油-水界面张力降至10^-3mN/m.在无碱条件下,对于大港油田枣园1256断块原油,当OCS活性剂质量分数达到0.2%时,油-水界面张力即可降至10^-3mN/m.大庆原油的平面模型驱油试验表明,OCS表面活性剂、碱和聚合物三元复合体系（ASP）的驱油效率比水驱提高20%以上.     

三元复合驱的驱油特征研究

大量室内研究和矿场试验结果表明,在高效的表活剂条件下,三元复合驱是一种非常有效的三次采 油方法,具有良好的应用前景。文中应用数值模拟技术并结合室内研究,给出了三元复合体系不同界面张 力和粘度比条件下,在非均质油层中的驱油特征。分析结果表明,三元复合驱与聚合物驱相比,对油层非 均质性有更大的适用范围;对于非均质油层的三元复合驱,采用增加体系的粘度和降低体系的界面张力的 方式都能获得较好的提高采收率效果,但高粘度是获得好的提高采收率的关键;采取分层注入的方式,或 者在三元复合驱后对高渗透层进行封堵,能更有效地采出中、低渗透层的剩余油,进一步提高采收率。本 项研究对认识三元复合驱的驱油机理和编制调整矿场试验方案提供了重要依据。     

聚合物/两性表面活性剂二元体系提高水驱后残余油采收率研究

针对三元复合驱中的碱大幅度降低聚合物溶液的黏弹性，降低波及效率和驱油效率，含碱驱油体系引起地层黏土分散和运移、形成碱垢、导致地层渗透率下降等问题，利用不加碱可形成超低界面张力的聚丙烯酰胺／两性表面活性剂二元复合体系，通过人造岩心驱油实验，研究了聚表二元复合体系提高水驱后残余油采收率的可能性。研究表明，聚表二元复合体系在驱替水驱后残余油中，可以同时发挥活性剂的超低界面张力特性和聚合物溶液的粘弹特性，使得该二元体系的采收率高于单一的表面活性剂体系和聚合物驱油体系，并且二元体系的聚合物浓度越高，采收率越高。     

大庆油田强碱三元复合驱表面活性剂配方优化

烷基苯磺酸盐表面活性剂的性能直接影响强碱三元复合驱的开发效果。通过研究原油组成、油砂吸附等对烷基苯磺酸盐表面活性剂浓度及强碱三元复合体系界面张力的影响,建立了原油分子量与表面活性剂当量之间的定量匹配关系。结果表明,依据该定量匹配关系选择合适当量的表面活性剂可使三元复合体系与大庆地区 不同原油间达到超低界面张力,提高了强碱三元复合体系的适应性;原油组成影响表面活性剂在油水相中的分配比例,原油中的沥青质含量越高,水相中的表面活性剂浓度越低,原油组成对表面活性剂当量的影响较小;油砂吸附改变了表面活性剂的当量及组成分布,导致三元体系中表面活性剂的浓度降低、三元体系界面张力升高,可采取增加高碳组分、调整表面活性剂当量的方法,扩大复合体系在地下运移过程中的超低界面张力作用距离。图11表3 参16     

稠油油藏污水活性碱/聚二元复合驱室内试验研究

羊三木油田碱/ 聚驱先导试验存在现场污水配制碱/ 聚二元复合驱体系时出现结垢堵塞地面管线、聚合物严重降解等问题，为此开展了污水配制新型碱/ 聚合物二元复合驱体系研究。采用抗钙镁结垢能力强、降低界面张力幅度大的活性碱与污水聚合物匹配，分析在污水配制条件下，不同碱型与聚合物匹配的驱油能力，以及在原油黏度高达530 mPa·s 时能否继续开展二元复合驱的问题。研究结果表明 :原油黏度为530 mPa·s，污水配制活性碱/ 聚合物二元复合体系溶液黏度为45 mPa·s 时，油水界面张力达到10－3 数量级，活性碱/ 聚合物二元复合驱比纯水驱提高采收率17% 以上；在原油黏度确定及油水界面张力已降至超低值时，超过碱/ 聚二元体系溶液浓度技术临界点后，即使继续增加溶液黏度，采收率也不会大幅度增加。该研究为普通稠油油藏注水开发后期化学驱提高采收率提供了新型有效的技术手段。     

The Effect of Alkali and Surfactant on Polymer Molecular Structure

Abstract

With the technical development of enhanced oil recovery (EOR), the alkali/surfactant/polymer (ASP) compound flooding technique has been the necessary choice in Daqing oilfield. Compared to average polymer flooding, ASP compound solution decreases the interfacial tension (IFT) between water and crude oil; however, the viscosity and viscoelasticity of ASP solution were performed by surfactant and alkali, both of which could affect the polymer moleculal structure and the oil recovery of ASP flooding. Considering practical requirements in oilfield development, much effort has been focused on the effect of alkali and surfactants on polymer solution by laboratory experiment and theoretical analysis. The results indicate that alkali and surfactants cause the interfacial tension decrease; at the same time, the molecular structure of the polymer is changed and the viscosity and viscoelasticity of polymer solutions are decreased. In addition, alkali neutralizes with negative ion on polymer molecular and causes the polymer molecular chains to curl up, forming a “band” molecular structure. Those actions could make viscoelastic behavior and rheological property of ASP solution weak.     

桩西115区块表面活性剂驱技术研究与应用

胜利油田桩西采油厂桩115区块属于高温中低渗油藏,为进一步改善区块注采矛盾,本文通过考察不同浓度4种甜菜碱表面活性剂溶液与桩115区块原油间的界面张力及其在石英砂表面的吸附规律,开发了以甜菜碱表面活性剂为主剂、以碱木素为牺牲剂的低界面张力驱油体系。该体系在石英砂表面的静态吸附量为0.4 mg/g;无需同碱复配,即可使油水界面张力降至5×10-4mN/m。物理模拟实验表明,在水驱后注入0.3 PV冻胶堵剂+0.3 PV低界面张力驱油体系,原油采收率可提高17%。2008年1月在桩115-5井组采用驱替方案进行了现场试验,截止2010年5月净增原油1632 t。图13参7     

Experimental investigation the effect of nanoparticles on micellization behavior of a surfactant: Application to EOR

Chemical stimulation such as surfactant flooding in petroleum reservoirs makes efforts to produce remained oil and improve sweep efficiency by means of different phenomena such as lowering interfacial tension and wettability alteration of reservoir rock. Implementing concentration of surfactant through surfactant flooding is one of the big challenges while interfacial tension between surfactant solution and oil after certain concentration involves little changes such as critical micelle concentration (CMC). This article highlights the effect of nanosilica on CMC of Zyziphus Spina Christi, as sugar-based surfactant, in aqueous solutions for enhanced oil recovery and reservoir stimulation purposes. A conductivity approach was selected to assess the CMC of the introduced surfactant in aqueous solution at 25°C. The influence of nanosilica concentrations on CMC variation of introduced surfactant is considered. It is found that CMC of introduced surfactant decreased while the concentration of the nanosilica increased. Results from this study can aim in optimum condition selection of surfactant flooding as an enhanced oil recovery ends.     

Design of Alkaline/Surfactant/Polymer (ASP) Slug and its use in Enhanced Oil Recovery

Abstract

Studies have been done to design an optimum composition of alkali/surfactant/polymer (ASP) slug and its application in flooding to increase the additional recovery of oil. A very low concentration of alkali and surfactant is used to achieve ultra-low interfacial tension between the trapped oil and the injection water, and polymer is used to increase the viscosity of the injection water for mobility control. Based on the experimental results of physico-chemical properties of polymer, surfactant, and alkali and their mutual interaction in solution, an ASP slug of composition SDS: 0.1 wt%, SDBS: 0.075 wt%, polyacrylamide: 2,000 ppm, and NaOH: 0.7 wt% has been recommended for flooding. Two sets of core-flooding experiments have been conducted using the designed ASP slug in a tri-axial core holder to measure the additional recovery of oil. The average additional oil recovery over conventional water flooding was found to be more than 20% of the original oil in place (OOIP).     

Dynamic Interfacial Tensions of 1-Phenylalkane Sulfonates

1-Phenylalkane sulfonates (with carbon chains of 12, 14, and 16) with high purity were prepared through a comparably simple way to study dynamic interfacial tensions against crude oil. During the investigation of dynamic interfacial tensions, interfacial tension minima were observed and the reason thereof was given. The effect of surfactant concentration on dynamic interfacial tensions was also studied to find that NaOH concentration can also affect the time reaching minima through affecting the activity of surfactant. For the sake of simplicity, the concept of “appearance” interfacial activity was proposed.     

Dynamic Interfacial Tensions of 1-Phenylalkane Sulfonates

Abstract

1-Phenylalkane sulfonates (with carbon chains of 12, 14, and 16) with high purity were prepared through a comparably simple way to study dynamic interfacial tensions against crude oil. During the investigation of dynamic interfacial tensions, interfacial tension minima were observed and the reason thereof was given. The effect of surfactant concentration on dynamic interfacial tensions was also studied to find that NaOH concentration can also affect the time reaching minima through affecting the activity of surfactant. For the sake of simplicity, the concept of “appearance” interfacial activity was proposed.