Laboratory Study on the Oil Displacement Properties of Sugar Amine Sulfonate Surfactant

A sugar amine sulfonate surfactant (SAS) was used to enhance oil recovery by chemical flooding. The interfacial tension between an SAS solution and four kinds of crude oil was determined. Oil (4) containing the largest amount of medium chain length components was the most suitable candidate because the IFT could be reduced to an ultralow range (10^?3 mN/m) at optimum NaCl concentration. Emulsions consisting of oil (4) and SAS solution and the adsorption density of SAS on sandstone were studied. Compared with A37 (alkyl ether sulfate), SAS ws able to form more stable emulsions and the adsorption density was equivalent in the typical concentration range of chemical flooding. Both SAS and A37 adsorption data on sandstone followed the Langmuir isotherm model. SAS increased the apparent viscosity of KY-1500 (modified polyacrylamide) in a low concentration range and improve the viscoelasticity. A combination of SAS and KY-1500 (SP) enhanced oil recovery by 16.05 versus 14.31% (using KY-1500 alone).     

A New Benzylated Fatty Acid Amide Amphoteric Surfactant Derived from Hydrogenated Castor Oil with Ultra-Low Interfacial Tension between Crude Oil and Brine

Hydrogenated castor oil from castor oil is promisingly used as raw materials for lubricants, coatings, cosmetics, and pharmaceutics due to high melting point and stable physical properties. However, the chemical modification of the hydrogenated castor oil has been rarely investigated. Here, we report a N-phenyl-fatty-amido-1-propyl-N,N-dimethyl-amino-carboxyl-betaine surfactant derived from hydrogenated castor oil with excellent interfacial properties through a rapid synthetic process, including direct alkylation, amidation, and quaternization. The interfacial tension between crude oil and brine was ultra-low for a low dosage of 0.007 g L⁻¹ of surfactant in aqueous solution without any alkali addition, which implies a potential application in enhanced oil recovery.     

How to Attain Ultralow Interfacial Tension and Three-Phase Behavior with Surfactant Formulation for Enhanced Oil Recovery: A Review. Part 4: Robustness of the Optimum Formulation Zone Through the Insensibility to Some Variables and the Occurrence of Complex Artifacts

In enhanced oil recovery, not only the low-tension performance, but also the robustness at optimum formulation is an important issue. The fourth part of our review series is dedicated to robustness, defined as the width of the zone exhibiting three-phase behavior around the optimum formulation, whatever the scanned variable. It is first corroborated from a screening of the available data in the literature that the tension minimum is inversely proportional to the square of the three-phase range in the HLD scale. However, since there is still an inaccuracy of about a factor 10 in the tension minimum, some significant improvement can be attained in some cases by increasing the three-phase behavior width in two ways. The first approach consists of finding systems that are insensitive to some formulation variable such as temperature, surfactant mixture composition or concentration, and water-to-oil ratio. The second way is to produce an artifact through which the optimum formulation is produced twice in a scan. If the distance between the two events in the scan is reduced down to be zero, their corresponding three-phase behavior zones merge and result in a wider WIII region with a low tension. Several cases of such events are reported: alkaline scans, anionic-nonionic and anionic-cationic mixture changes, linear change in composition in three-surfactant mixture, partial precipitation from a surfactant mixture in a salinity scan, and excessive partitioning of polyethoxylated nonionics. More complex transitions with three effects in a single scan or three concomitantly scanned variables show even more possibilities in practice.     

癸基萘磺酸盐表面活性剂的组成-界面张力关系

该文采用廉价易得的萘和α-癸烯为原料,以氯铝酸离子液体催化Friedel-Crafts烷基化反应,合成了中间体癸基萘(DN),再经磺化与中和反应合成了结构明确、组成可调的驱油用阴离子型表面活性剂复合癸基萘磺酸钠(DNS)。中间体DN通过FTIR和1HNMR进行结构表征,产品DNS采用HPLC-MS分析组成,并测得其克拉夫特点小于0℃。测定了DNS对正构烷烃模拟油相的界面性能,结果表明,DNS1-1和DNS3均可在较低表面活性剂质量分数(0.25%～0.4%)下将油水界面张力降低至10-3mN/m数量级,并且具有良好的耐盐性,不同批次DNS1-1产品均能维持组成基本不变并稳定地重现组成相关的超低界面张力。     

Effect of Nanoparticles on Viscosity and Interfacial Tension of Aqueous Surfactant Solutions at High Salinity and High Temperature

Surfactant flooding has widely been used as one of the chemically enhanced oil recovery (EOR) techniques. Surfactants majorly influence the interfacial tension, γ, between oil and brine phase and control capillary number and relative permeability behavior and, thus, influence ultimate recovery. Additives, such as nanoparticles, are known to affect surfactant properties and are regarded as promising EOR agents. However, their detailed interactions with surfactants are not well understood. Thus, in this work, we examined the influence of silica nanoparticles on the ability of surfactants to lower γ and to increase viscosity at various temperatures and salinities. Results show that the presence of nanoparticles decreased γ between n-decane and various surfactant formulations by up to 20%. It was found that γ of nanoparticles–surfactant solutions passed through a minimum at 35 °C when salt was added. Furthermore, the viscosity of cationic surfactant solutions increased at specific salt (1.5 wt.%) and nanoparticle (0.05 wt.%) concentrations. Results illustrate that selected nanoparticles–surfactant formulations appear very promising for EOR as they can lower brine/n-decane interfacial tension and act as viscosity modifiers of the injected fluids.     

聚合物驱提高采收率研究

聚合物驱是一种比较有效的提高原油采收率的三次采油方法。综述了聚合物驱技术在国内外的应用和研究进展,分析了聚合物驱的驱油机理。介绍了常见的聚合物驱并提出了发展聚合物驱急需解决的问题。     

Investigation of Interfacial Tension Reduction,Wettability Alteration,and Oil Recovery Using a New Non-ionic Oil-Based Surfactant from Gemini Surfactants Family Coupled with Low-Salinity Water: Experimental Study on Oil-Wet Carbonate Rock

Low-salinity surfactant (LSS) flooding is a combined enhanced oil recovery (EOR) technique that increases oil recovery (OR) by altering the rock surface wettability and reducing oil–water interfacial tension (IFT). In this study, optimum concentrations of several types of salt in distilled water were obtained on the basis of IFT experiments for the preparation of low-salinity water (LSW). Then, a new oil-based natural surfactant (Gemini surfactant, GS) was combined with LSW to investigate their effects on IFT, wettability, and OR. Experimental results showed that LSW is capable of reducing IFT and contact angle, but the synergy of GS and the active ions Mg²⁺, Ca²⁺, and SO₄²⁻ in LSW was more effective on IFT reduction and wettability alteration. The combination of 1000 ppm MgSO₄ and 3000 ppm GS led to a decrease in contact angle from 134.82° to 36.98° (oil-wet to water-wet). Based on core flooding tests, LSW injection can increase OR up to 71.46% (for LSW with 1000 ppm MgSO₄), while the combination of GS and LSW, as LSS flooding, can improve OR up to 84.23% (for LSS with 1000 ppm MgSO₄ and 3000 ppm GS). Therefore GS has great potential to be used as a surfactant for EOR.     

Porous Bed Saturation Changes in Elution Process with Surfactant Solutions in Advanced Oil Recovery

The elution of high-viscosity substances from a granular bed using fluids with different interfacial tensions was investigated. Analyses of changes in flow resistance and the degree of saturation of the deposit during the process were conducted. The elution process was described by means of the modified concept of capillary bundles, based on the Blake-Kozeny-Carman relationship. The use of this dependence can be helpful in determining the degree of saturation of the deposit at any given time of elution process only on the basis of the flow hydrodynamics and parameters of the deposit and liquid. This makes it possible to estimate the residual saturation of the bed without the need to perform troublesome experimental research for the content of oil in the reservoir.     

新型Gemini表面活性剂-石油酸盐复合驱油剂的研究

为了提高油田驱油剂降低油/水界面张力的能力,以提高原油的采收率,在研究了石油磺酸盐表面活性剂表界面活性的基础上,研制了Gem in i表面活性剂-石油磺酸盐复合驱油剂,采用TX-500界面张力仪测定了复合驱油剂降低胜利油田油/水界面张力的能力。研究表明:在一定的浓度条件下,石油磺酸盐能降低油/水界面张力至1×10-2mN.m-1左右,磺酸盐型Gem in i表面活性剂-石油磺酸盐复合驱油剂能降低油/水界面张力至4×10-4~6×10-4mN.m-1左右。与传统驱油剂相比,磺酸盐型Gem in i表面活性剂-石油磺酸盐复合驱油剂降低油/水界面张力的能力得到了显著提高,从而提高原油的采收率。     

A Zwitterionic Surfactant Bearing Unsaturated Tail for Enhanced Oil Recovery in High‐Temperature High‐Salinity Reservoirs

High‐temperature/high‐salinity (HTHS) reservoirs contain a significant fraction of the world's remaining oil in place and are potential candidates for enhanced oil recovery (EOR). Selection of suitable surfactants for such reservoirs is a challenging task. In this work, two synthesized zwitterionic surfactants bearing a saturated and an unsaturated tail, namely 3‐(N‐stearamidopropyl‐N,N‐dimethyl ammonium) propanesulfonate and 3‐(N‐oleamidopropyl‐N,N‐dimethyl ammonium) propanesulfonate, respectively, were evaluated. The surfactant with the unsaturated tail showed excellent solubility in synthetic seawater (57,643 ppm) and in formation brine (213,734 ppm). However, the unsaturated surfactant with a saturated tail showed poor solubility, and therefore it was not evaluated further. The thermal stability of the synthesized unsaturated surfactant solution in seawater was evaluated by heating the solution at 90 °C in a sealed aging tube for 2 weeks. The thermal stability of the unsaturated surfactant was confirmed by FTIR and NMR analysis of the aged samples at such harsh conditions. The critical micelle concentration (CMC) of the synthesized unsaturated surfactant in seawater was 1.02 × 10^?4 mol L^?1, while the surface tension at CMC was 30 mN m^?1. The synthesized unsaturated surfactant was able to reduce the oil–water interfacial tension to ~10^?1 mN m^?1 at different conditions. A commercial copolymer of acrylamide and 2‐acrylamido‐2‐methylpropane sulfonic acid (AM‐AMPS) was tested for EOR applications in HTHS conditions. The addition of the synthesized unsaturated surfactant to the AM‐AMPS copolymer increased the viscosity of the system. The increase in oil recovery by injecting the unsaturated surfactant solution and the surfactant–polymer mixture in solution was 8 and 21%, respectively. The excellent properties of the synthesized unsaturated surfactant show that surfactants with an unsaturated tail can be an excellent choice for HTHS reservoirs.     

A New Series of Double-Chain Single-Head Sulfobetaine Surfactants Derived from 1,3-Dialkyl Glyceryl Ether for Reducing Crude Oil/Water Interfacial Tension

A new series of sulfobetaine surfactants with double-chain single-head structure were derived from 1,3-dialkyl glyceryl ethers and their performances in reducing Daqing crude oil/connate water interfacial tension (IFT) in the absence of alkali were studied. With a large hydrophilic head group and double hydrophobic chains, these surfactants are efficient at reducing crude oil/connate water IFT. Those with didecyl and dioctyl are good hydrophobic surfactants that can reduce Daqing crude oil/connate water to ultra-low IFT by mixing with a small molar fraction of various conventional single-chain hydrophilic surfactants, such as α-olefin sulfonates, dodecyl polyoxyethylene (10) ether, and cetyl dimethyl hydroxypropyl sulfobetaine. The asymmetric double-chain sulfobetaine derived from 1-decyl-3-hexyl glyceryl ether can reduce Daqing crude oil/connate water IFT to ultra-low solely over a wide concentration range (0.03–10 mM or 0.0017–0.58 wt.%), which allows for use of an individual surfactant instead of mixed surfactants to avoid chromatographic separation in the reservoir. In addition, formulations rich in sulfobetaine surfactants show low adsorption on sandstone, keeping the negatively charged solid surface water-wet, and forming crude oil-in-water emulsions. These new sulfobetaine surfactants are, therefore, good candidates for surfactant-polymer flooding free of alkali.     

高盐油藏提高采收率的室内研究

高盐油藏在水驱采油之后仍有相当一部分原油滞留在地层中,很难将其采出,因此可选用化学方法动用,但高盐油藏地层水矿化度相对较高,温度相对较高,普通表面活性剂很难满足如此苛刻条件下的油藏环境。因此需要将表面活性剂进行复配,充分发挥各种活性剂的优势,进而达到提高采收率的目的。针对玉门油田鸭儿峡L油藏地层水矿化度的特点,采用阴离子-两性表面活性剂复配,通过测定不同复配比和活性剂浓度下的油水界面张力,最终确定了适用于L油藏的表面活性剂驱油复配体系。实验表明在石油磺酸盐A与C14BE复配比为1:4、1:3,总浓度为0.6%、0.1%时,油水界面张力达到了10-3 m N/m级别。此驱油配方适用于L油藏提高采收率的要求。     

强化分散体系提高稠油油藏采收率影响因素实验研究

针对LD5-2油田储层特征及流体性质,以强化分散体系提高采收率幅度为研究指标,通过室内实验模拟,得出稠油强化分散提高采收率的影响因素。结果表明,稠油油藏单靠增加药剂浓度增油效果十分有限,而在注入强化分散体系前采取调剖措施后,强化分散体系可使采收率明显增加;油井吞吐注入速度或注液压差大小应当与储层物性和流体性质相适应,本次实验最佳注入速度和注入液压差约为0.3 m L/min和0.25 MPa;采取堵水剂+强化分散体系措施组合方式可以取得更好增油降水效果。     

From Phase Behavior to Understand the Dominant Mechanism of Alkali-Surfactant-Polymer Flooding in Enhancing Heavy Oil Recovery

The primary objective of this work was to understand the dominant mechanism(s) of alkali‐surfactant‐polymer (ASP) flooding in enhancing heavy oil recovery. Chemical formulations were first optimized based on phase behavior studies. The data indicated that alkali and surfactant created a synergistic effect at the oil/water interface, which further decreased the interfacial tension (IFT) and improved the emulsification. However, it was also found that the addition of alkali was detrimental to the viscous properties of the chemical systems and caused the ultimate oil recovery to decrease. In other words, the macroscopic sweep efficiency as a result of viscosity was the primary factor determining the overall recovery of heavy oil followed by emulsification, which was verified by the phase behavior of the effluent. Based on the experimental results, we found that for this targeted heavy oil reservoir, surfactant‐polymer (SP) flooding was more appropriate than ASP flooding and it was not necessary to decrease the IFT to the ultralow level (10^?3 mN/m) using alkali. Through chemical flooding, the incremental oil recovery was increased up to 27% of original oil in place, indicating the potential of this technique in heavy oil reservoirs.     

强化分散体系提高采收率影响因素研究

根据渤海地区稠油油田储层地质和流体特征以及现阶段开发现状,以BZ25-1S油田储层和流体为实验对象,开展了原油黏度、药剂浓度和驱替方式对驱油效果影响实验研究。结果表明,随原油黏度增加,水驱或调驱增油降水效果变差;与水驱相比较,"调剖+水驱"可以较大幅度扩大波及体积和提高采收率。与单独调剖相比较,采取"调剖剂+强化分散体系"注入段塞组合,不仅可以扩大波及体积,而且能够提高洗油效率,采收率增幅进一步提高。     

环烷基油加氢生产润滑油技术进展

介绍了环烷基油的特点及其在国内外的市场状况,并分别对石油化工科学研究院（RIPP）和抚顺石油化工研究院（FRIPP）开发的以环烷基油为原料通过全氢法加氢技术生产变压器油、冷冻机油、工业白油、光亮油、橡胶填充油等润滑油产品及工业应用情况进行了阐述。     

CO_2驱油提高采收率技术的研究现状与分析

针对化石能源利用过程中排放CO_2引起的温室效应问题,同时为满足油藏高效开发的要求,介绍一种CO_2驱油提高采收率技术,分析其驱油机理,并总结目前国内外EOR技术的应用与开发现状,指出目前我国EOR应用的前景。     

液相磺化法制备三次采油用石油磺酸盐

研究了克拉玛依炼厂减压四线糠抽馏分油与液相三氧化硫在1,2-二氯乙烷溶剂存在下的磺化反应,磺化产物经中和、分水、浓缩等处理,得到石油磺酸盐产品。采用阳离子两相滴定-比较分析法测定反应产物中的活性物含量,讨论了酸油比、反应温度、溶剂与油的比例、加酸速度及老化时间对活性物含量的影响。结果表明,酸油比、反应温度和加酸速度对活性物含量影响较大,溶剂和油的比例次之,而老化时间对活性物含量的影响较小,优化条件下活性物含量高达67.27%。     

Spontaneous Imbibition Experiments of Enhanced Oil Recovery with Surfactants and Complex Nano-Fluids

Two types of porous media were analyzed with the intention of exploring alternative enhanced oil recovery methods. Core samples were taken from the Tensleep Formation of the Black Mountain Field in Hot Springs County, WY. The lithology is mainly sandstone and dolomite. The measured effective porosity values ranged from 13.0 to 18.0%, and permeabilities from 19 to 68 md. Production from the Tensleep and Phosphoria formations using conventional methods has resulted in a low secondary recovery factor, possibly due to high capillary forces and an oil-wet formation. Different surfactants were investigated to determine the viability of a possible enhanced oil recovery process using a spontaneous imbibition process in Amott cells. A very high enhanced recovery factor of more than 89% was achieved using a complex nano-fluid that consists of a mixture of surfactant, solvent, co-solvent and water. These recovery factors compared with 13% by brine imbibition and up to 21% using commercial surfactants. At the other end of the scale, very high porosity volcanic pumice was also subjected to the same tests. For this rock the porosity values ranged from 65 to 90% and permeabilities were 2.0–2.7 d. Secondary recovery showed values up to 81% on spontaneous imbibition and up to 91% when surfactants were employed. These experimental results indicate that pumice has favorable reservoir characteristics, but, due to its weak brittle nature, it would not be expected that it could withstand the overburden stress at any significant depth. However, it does represent a useful laboratory specimen.     

A Review of Gemini Surfactants: Potential Application in Enhanced Oil Recovery

Gemini surfactants are a group of novel surfactants with more than one hydrophilic head group and hydrophobic tail group linked by a spacer at or near the head groups. Unique properties of gemini surfactants, such as low critical micelle concentration, good water solubility, unusual micelle structures and aggregation behavior, high efficiency in reducing oil/water interfacial tension, and interesting rheological properties have attracted the attention of academic researchers and field experts. Rheological characterization and determination of the interfacial tension are two of the most important screening techniques for the evaluation and selection of chemicals for enhanced oil recovery (EOR). This review deals with rheology, wettability alteration, adsorption and interfacial properties of gemini surfactants and various factors affecting their performance. The review highlights the current research activities on the application of gemini surfactants in EOR.