Spontaneous emulsification aspect of enhanced oil recovery

Recent studies have suggested the possibility of spontaneous emulsification as a mechanism for enhanced oil recovery (EOR). The discussions have, however, remained essentially qualitative. A study was therefore undertaken to estimate quantitatively the contribution of spontaneous emulsification as an EOR mechanism. The tests were conducted on several bulk liquid/liquid systems as well as by displacement experiments in unconsolidated synthetic sand packs. Spontaneous emulsification was found to be a mechanism for EOR: the estimated extra contribution to EOR due to this mechanism was found to be significant in laboratory scale displacement experiments. Tertiary recovery was always greater when spontaneous emulsification was evident than otherwise. Results of tests on bulk liquid/liquid systems indicate that the occurrence or absence of spontaneous emulsification can be correlated with the values of ‘partition parameter’. It may be concluded that higher oil recoveries may be achieved in chemical EOR processes where interface mass transfer (and the accompanying spontaneous emulsification) occurs. The evaluation of efficiency of residual oil mobilisation through the capillary number theory (with and without spontaneous emulsification) is also discussed. Displacement tests with spontaneously emulsifying systems showed that residual oil left behind a conventional waterflood was mobilised in a range of capillary numbers much less than that which applies to low-tension waterfloods.     

TRANSIENT INTERFACIAL TENSION BEHAVIOR BETWEEN ACIDIC OILS AND ALKALINE SOLUTIONS

A study of the dynamic interfacial tension behavior of reacting acidic oil/alkaline solutions has been conducted for both an artificially acidified synthetic oil and a real crude oil for four different alkalis at various concentrations. The IFT values between a 10 mM acidified synthetic oil and various 25 mM alkaline solutions, before the minimum IFT value was reached, were found to be in the descending order: KOH, NaOH, Na₂SiO₃ and LiOH. The corresponding IFT values between diluted Lloydminster heavy crude oil and the same alkaline solutions, again before the minimum was reached, were found to be in the descending order: LiOH, NaOH, Na₂SiO₃ and KOH. The crude oil exhibited lower minimum IFT values against alkaline solutions than the synthetic acidified oil. The general trend of decreasing IFT towards a minimum value followed by an increase in IFT thereafter was noted for all solutions tested.     

聚表剂纳米催化剂驱油体系效果评估

聚表剂驱油技术是一种集调剖及驱替为一体的新型驱油技术,主要是通过增粘性,粘弹性和乳化性这三种性能来提高采收率。纳米催化剂材料在石油化工工业中具有改善产品构造,提高产品质量、产率和附加值的作用。在研究聚表剂和纳米催化剂在稠油热采中的主要作用以及他们提高采收率效果的同时,探究聚表剂和纳米催化剂混合后,同时注入地层是否能同时发挥二者优势,并寻求最优化的聚表剂-催化剂驱油体系,从而极大的提高原油采收率。纳米催化剂的注入性好,聚表剂的流度控制作用强,先注聚表剂扩大波及体积,后注入纳米催化剂改善原油物性,最后蒸汽吞吐能够提高单井吞吐效果。     

Aggregation Behavior and Micellar Properties of Sodium Salts of Naphthenic Acid Mixtures

The aim of this study was to investigate micellar and self‐assembly properties of four sodium salts of naphthenic acid mixtures by determination and comparative analysis of their critical micelle concentration values at seven different temperatures ranging from 10 to 40 °C using spectrofluorophotometric measurements. It was concluded that fractions having the lowest percentage of aliphatic structures give the least flexible micelles due to sterically rigid structure of cyclic side chains, what makes them difficult to pack in the micellar core. Additionally, surface properties of aqueous solutions of investigated mixtures were studied by the determination of the maximum surface excess, Γ_max and the minimum area per surfactant molecule (A_min) values.     

Mixed Micelles of Surface Active Ionic Liquid (SAIL)–Octylphenol Ethoxylate: A Novel Reaction Medium for Selective Oxidation of Toluene to Benzaldehyde

Ionic liquids have been found to be suitable alternatives to volatile organic solvents in chemical transformation. Through a proper choice of cations and anions, the properties of an ionic liquid can be tuned so that it resembles an amphiphile. Such specially designed molecules are known as surface-active ionic liquids (SAIL). Like conventional surfactants, SAIL also form aggregates in an aqueous medium. Studies show that the mixing of SAIL with conventional surfactants leads to synergistic micellization. However, very few reports are available on the application of such systems as reaction media. Present study focuses on the application of mixed micelles of 1-tetradecyl-3-methylimidazol-1-ium bromide, ([C₁₄mim]Br) with nonionic surfactant, Octylphenol ethoxylate with 10 moles of ethylene oxide (OPE-10). Enhanced solubilization and selective catalytic oxidation of toluene using hydrogen peroxide as an oxidant and tungstic acid as a catalyst have been studied in detail using this system.     

How to Attain an Ultralow Interfacial Tension and a Three-Phase Behavior with a Surfactant Formulation for Enhanced Oil Recovery: A Review. Part 2. Performance Improvement Trends from Winsor’s Premise to Currently Proposed Inter- and Intra-Molecular Mixtures

The minimum interfacial tension occurrence along a formulation scan at the so-called optimum formulation is discussed to be related to the interfacial curvature. The attained minimum tension is inversely proportional to the domain size of the bicontinuous microemulsion and to the interfacial layer rigidity, but no accurate prediction is available. The data from a very simple ternary system made of pure products accurately follows the correlation for optimum formulation, and exhibit a linear relationship between the performance index as the logarithm of the minimum tension at optimum, and the formulation variables. This relation is probably too simple when the number of variables is increased as in practical cases. The review of published data for more realistic systems proposed for enhanced oil recovery over the past 30 years indicates a general guidelines following Winsor’s basic studies concerning the surfactant–oil–water interfacial interactions. It is well known that the major performance benefits are achieved by blending amphiphilic species at the interface as intermolecular or intramolecular mixtures, sometimes in extremely complex formulations. The complexity is such that a good knowledge of the possible trends and an experienced practical know-how to avoid trial and error are important for the practitioner in enhanced oil recovery.     

Micellar association in simultaneous presence of organic salts/additives

Viscosity measurements under Newtonian flow conditions had been performed on cetyltrimethylammonium bromide (CTAB) aqueous solutions in the combined presence of sodium salts of aromatic acids (sodium salicylate, NaSal; sodium benzoate, NaBen; sodium anthranilate, NaAn) and organic additives (1-hexanol, C₆OH; n-hexylamine, C₆NH₂) at 30°C. On addition of C₆OH or C₆NH₂, the viscosity of 25 mM CTAB solution remained nearly constant without salt as well as with a lower salt concentration. This is due to low CTAB concentration which is not sufficient to produce structural changes in this concentration range of salts. However, as the salt concentration was increased further, the effect of C₆OH/C₆NH₂ addition was different with different salts: The viscosity first increased; then a decrease was observed with the former while with C₆NH₂ a decrease followed by constancy appeared in plots of relative viscosities (η _r ) vs. organic additive concentrations. At further higher salt concentration, the magnitude of η _r was much higher. The viscosity increase is explained in terms of micellar growth and the decrease in terms of swollen micelle formation (due to interior solubilization of organic additive) or micellar disintegration (due to formation of water + additive pseudophase).     

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。     

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。     

RECOVERY OF FATTY ACID FROM A SOLVATED HYDROCARBON MIXTURE APPLICABLE TO THE BEAVER-HERTER SOLVENT EXTRACTION PROCESS

The Herter process is a patented enhanced oil recovery process that proposes the use of a fatty acid as a solvent to recover petroleum from an oil reservoir or a tar sand. The fatty acid solvent is injected into a reservoir formation or mixed with a tar sand in order to reduce the viscosity and increase the mobility of the petroleum.

The recovery and recycle of the fatty acid solvent are fundamental parts of the process. The Herter process proposes to recover the fatty acid by saponification, migration of the soap to the aqueous phase, and desaponification of the resulting soap phase. However, the formation of a hydrocarbon-soap-water emulsion severely limits the proposed process. Addition of methanol limits emulsification to allow a meaningful separation to be accomplished.

An evaluation of two proposed revisions to the Herter process was made based on batch experiments involving the recovery of oleic acid, linolenic acid, and Georgia Pacific XTOL™304 fatty acid from solvated mixtures with n-heptane. In both of these methods, methanol was introduced to the process as a cosolvent for the saponifying base (sodium hydroxide). The two methods differed in the manner of methanol recovery. In method 1, the saponification heavy phase was distilled to recover methanol. In method 2, the desaponification heavy phase was distilled to recover methanol.

Both of these methods had fatty acid recoveries greater than 84%, n-heptane recoveries greater than 89%, and methanol recoveries greater than 67%. Method 1 recovered purer fatty acid and a slightly greater percentage of n-heptane. Method 2 recovered a greater percentage of both fatty acid and methanol. Method 2 was found to be superior when high purity of the recovered fatty acid product was not required.     

How to Attain Ultralow Interfacial Tension and Three-Phase Behavior with a Surfactant Formulation for Enhanced Oil Recovery: a Review—Part 3. Practical Procedures to Optimize the Laboratory Research According to the Current State of the Art in Surfactant Mixing

The minimum interfacial tension to be reached in enhanced oil recovery by surfactant flooding implies the attainment of a so-called optimum formulation. Part 1 of the present review showed that this formulation may be described as a numerical correlation between the involved variables defining the oil, the water, the surfactant and the temperature. Since it is unlikely to find a single surfactant matching the crude/brine/T/P system characteristic of a reservoir, a mixture of at least two surfactant species is always used. The scan technique method to test the mixing requires about ten interfacial tension or phase behavior experiments and results in a single data. Hence, the scan experiments have to be repeated many times to find a minimum tension which is low enough, e.g. 0.001 mN/m, for the given crude oil-brine system. Part 2 of this review has shown that there are many formulation variables and thus too many possibilities to easily choose experimental conditions. Since there is no simple method to select two or more surfactant species, the choice is made from partial experience or intuition, and sometimes at random. The laboratory time and cost to reach an appropriate optimum formulation is often excessive. Part 3 of this review shows that by cleverly using a three-surfactant mixture, the experimental work to attain a very low interfacial tension for a given reservoir case can be considerably reduced. It is a matter of using the available information along a proper sequential step by step path toward the optimum.     

SIMULTANEOUS HEAT AND FLUID FLOW IN POROUS MEDIA: CASE STUDY: STEAM INJECTION FOR TERTIARY OIL RECOVERY

Heat transfer and fluid flow in porous media occur simultaneously in thermal enhanced oil recovery and significantly increase the rate of energy transfer. The purpose of this investigation was to take advantage of such contemporary transfers and to study heavy oil recovery efficiency using hot-water flooding, cold-water flooding, and steam injection into porous media. A set of multistage laboratory tests was performed to find the temperature profile during steam injection as a means of tertiary oil recovery. Sand-packed models were utilized to investigate the oil recovery efficiency during cold and hot water injection as well as steam flooding for both secondary and tertiary oil production stages. An oil bank was formed in steam injection during the tertiary oil recovery from a vertical standing sand-packed model, resulting in very high oil recovery efficiency. Steam injection was found to be very effective, compared to cold- and hot-water flooding, for the recovery of heavy oil. Based on the principles of transport phenomena in porous media, a mathematical model was developed to predict the temperature profile during the steam injection process. Satisfactory agreement is achieved between the temperature profile predicted from the model and the experimental results.     

基于响应面分析的聚合物驱注入参数优化方法

通过引入响应面设计理论,建立了基于数值试验的聚合物驱用量与聚合物浓度的优化方法。新方法通过性能响应试验回归得到响应曲面,得到了聚合物用量及聚合物浓度等优化目标变量与增采幅度之间的近似函数关系,将注入参数优化转换为响应曲面的求解与分析。该方法不仅可以显著降低聚合物驱方案优化过程中的数值模拟计算工作量,并通过绘制响应曲面,得到优化目标变量与增采幅度间的三维可视响应曲面。实例应用结果表明该方法简便易行、准确可靠,对于提高聚合物驱注入参数优化的效果和效率具有一定意义。     

SIMULTANEOUS HEAT AND FLUID FLOW IN POROUS MEDIA: CASE STUDY: STEAM INJECTION FOR TERTIARY OIL RECOVERY

Heat transfer and fluid flow in porous media occur simultaneously in thermal enhanced oil recovery and significantly increase the rate of energy transfer. The purpose of this investigation was to take advantage of such contemporary transfers and to study heavy oil recovery efficiency using hot-water flooding, cold-water flooding, and steam injection into porous media. A set of multistage laboratory tests was performed to find the temperature profile during steam injection as a means of tertiary oil recovery. Sand-packed models were utilized to investigate the oil recovery efficiency during cold and hot water injection as well as steam flooding for both secondary and tertiary oil production stages. An oil bank was formed in steam injection during the tertiary oil recovery from a vertical standing sand-packed model, resulting in very high oil recovery efficiency. Steam injection was found to be very effective, compared to cold- and hot-water flooding, for the recovery of heavy oil. Based on the principles of transport phenomena in porous media, a mathematical model was developed to predict the temperature profile during the steam injection process. Satisfactory agreement is achieved between the temperature profile predicted from the model and the experimental results.     

Development of Novel Amidosulfobetaine Surfactant–Polymer Systems for EOR Applications

Experimental studies were conducted to evaluate the thermal stability and rheological properties of novel surfactant–polymer (SP) systems for enhanced oil recovery applications. One in-house synthesized amphoteric amidosulfobetaine surfactant 3-(N-pentadecanamidopropyl-N,N-dimethylammonium)propanesulfonate and three different polymers were evaluated. Polymer A was a terpolymer of acrylamide, acrylamido tert-butyl sulfonate, and acrylic acid, whereas polymers B and C were terpolymers of acrylamide, N-vinylpyrrolidone, and acrylamido tert-butyl sulfonate with different anionicity. Long-term thermal stability of the surfactant was assessed using FTIR, ¹H NMR, and ¹³C NMR. The surfactant was compatible with seawater at 90 °C and no precipitation was observed. Structural analysis showed good thermal stability and no structural changes were observed after aging at 90 °C. The effects of surfactant concentration, shear rate, salinity, and polymer concentration on rheological properties of the SP systems were determined. Polymer A showed highest viscosity among the investigated polymers in deionized and seawater. The interactions between the surfactant and polymer A were assessed using rheological measurements. In the presence of salts, the viscosity of all three polymers reduced significantly as a result of charge screening. At low shear rates, the added surfactant slightly decreased the viscosity and storage modulus of polymer A. At high shear rates, the effect of the surfactant on the viscosity and storage modulus of polymer A was insignificant.     

低渗透油藏泡沫驱油机理及应用现状研究

低渗透油气藏在世界范围内分布范围广,储量大,在新探明储量中占得比例越来越大,是全球油气资源增产的主要来源,合理高效的开发低渗透油藏中的油气资源,是未来面临的主要问题。泡沫驱油作为继水驱、气驱之后新的驱油方式,结合了气体和泡沫的优点,以独特的优势越来越得到人们的重视,是低渗透油藏提高采收率的又一个重要途径。分析了泡沫驱相对于其他驱油方式的优势,概述了泡沫驱油的驱油机理,简要分析了空气泡沫驱、氮气泡沫驱各自特点,对泡沫驱油在国内外油田的应用现状做了介绍。对泡沫驱油存在的问题做了阐述,并提出了泡沫驱油的发展方向。     

国内轻质油藏注空气、空气泡沫提高采收率效果分析

在重点调研国内油田空气、空气泡沫驱的基础上,论述了注空气、空气泡沫低温氧化技术的原理,对我国油田开展注空气、空气泡沫驱技术的实际效果以及潜力进行了的分析,认为注空气低温氧化工艺技术安全可控,不但可以解决我国储量丰富的低渗透油藏所面临的开发难题,而且可以进一步提高水驱、聚合物驱后油藏的采收率。随着技术进步,注空气低温氧化技术是我国乃至全世界注气提高采收率技术发展的必然趋势。并通过对现场应用情况分析,给出了对轻质油藏注空气、空气泡沫提高采收率的一些建议。     

N,N-双十二烷基-3,6-O-磺丙基壳聚糖对紫杉醇的增溶作用

合成高取代度的N,N-双十二烷基-3,6-O-磺丙基壳聚糖（SPDLCS）双亲性衍生物,通过透析法制备了SPDLCS载紫杉醇（PTX）胶束,考察了投料比对载药量、包封率、胶束粒径和Zeta电位的影响,并对胶束形态及其稳定性进行了研究。结果表明,紫杉醇以无定形态包载于胶束的疏水内核中,最优投料比为SPDLCS∶PTX=1∶1.1,载药量为50.36 %,包封率为92.2 %,对紫杉醇的增溶能力达6.08 mg/mL。载药胶束呈现分散性良好的球形颗粒,平均粒径为141.1 nm,Zeta电位为?34.1 mV。稳定性实验表明SPDLCS载紫杉醇胶束具有良好的稳定性,SPDLCS是潜在的疏水药物高增溶载体材料。     

国内外火烧油层研究进展与应用

随着常规油气资源开采的枯竭,我国各大油田已经进入了二次,三次采油时期。稠油作为一种非常规石油资源具有极大的开采价值。火烧油层技术是稠油开采的重要手段,因此对火烧技术的研究有助于稠油资源的开发。文章在调研国内外火烧油层研究与试验文献的基础上,对国内外火烧油层技术进行了全面的总结和概括,介绍了火烧技术的室内试验与现场应用,提出下一步火驱发展的方向为反应原理的研究与现场操作的实施规划。     

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。