Effects of Sand Fraction on Toluene‐diluted Heavy Oil in Water Emulsions in Turbulent Flow

The impact of the presence of sand on emulsification of toluene‐diluted heavy oil in simulated process water was systematically studied as a function of agitation time, in a stirred tank. Droplet size distributions were measured by light scattering technique. Optical microscopy and high‐speed video micrography were used to visually monitor agitation and emulsion stability. Results showed that the Sauter mean diameters of the droplets decreased with increasing sand content. Droplet breakage followed a first‐order kinetic model for all mixing speeds. Plots of droplet volume percent frequency versus droplet size followed lognormal distribution. The distribution span broadened into lower sizes with increased sand content. Emulsions were stable for over 48 h after formation.     

Paraffin Oil Emulsions for the Absorption of Toluene Gas

Water‐in‐oil‐in‐water (W/O/W) and water‐in‐oil (W/O) emulsions of paraffin oil were prepared with sorbitan monooleate (Span 80)/polyoxyethylene sorbitan monooleate (Tween 80) or polyethylene glycol monostearate (SG‐6), respectively. The physical characteristics and the absorption of toluene gas in these emulsions were investigated to evaluate the influence of the emulsifier dosage and the oil/water ratio. Both investigated W/O/W emulsions provided high stabilities and low viscosities. The absorption of toluene gas was excellent, with little foam occurring during the absorption. Although the W/O emulsions with 2–5 % SG‐6 were of high stability, their high viscosities strongly limited their application as volatile organic compound absorbents. Stable emulsions consisted of small and uniform droplets and some emulsions underwent mild demulsification after the absorption.     

物性对油滴剪切变形影响的模拟分析

以简单线性剪切流为背景,采用VOF模型及若干自定义子程序进行模拟分析,探讨物性对油滴变形和破碎的影响关系。模拟表明:粘度对变形起到抑制作用,粘度越大,变形越难,更能耐受剪切流动;表面张力越小,油滴越容易发生变形和破碎,稳定性越差,表面张力阻止了油滴的变形;油滴粒径越大,越易变形、破碎,越不稳定。     

油田发泡剂的稳定性能改良的研究

研究了在相同体积,搅拌时间及搅拌转速下,不同添加剂对油田开发泡剂的起泡量,泡沫均匀程度及泡沫中衰期的影响,取得了较佳工艺条件。     

稠油流动边界层水基泡沫减阻模拟

针对稠油水环输送的中心油流偏心问题,提出稠油流动边界层在AFS-2水基泡沫作用下的模拟实验方法,设计加工相应的管流模拟装置及泡沫发生、注入与泡沫层生成系统.用201甲基硅油模拟稠油,实验研究稠油在水基泡沫作用下的水平管流阻力特性,分析泡沫与硅油的流速与流量比对硅油流动流型和减阻效果的影响.基于上部泡沫-下部液膜复合边界层假设,建立硅油-泡沫-液膜中心环状水平管流的压降预测模型.结果表明:20℃室温下,当泡沫与硅油流量比为0.2～0.5时,硅油流动减阻率高于70%,其机理可归结为油壁间形成了上部泡沫-下部液膜的复合隔离润滑层;理论预测值与实验测量值吻合良好,相对误差为－17.55%～9.76%.     

掺稀技术在轮西油田的应用

结合轮西油田油藏现状，对稠油掺稀技术在该油田的应用状况，包括掺稀比、含水率、掺稀压力、掺稀温度、掺稀点对稠油掺稀技术影响和稠油掺稀集输流程，做了较为详尽的论述。     

A Comparison of Steam Reforming of Two Model Bio‐Oil Fractions

Two model bio‐oil fractions were chosen as two different major classes of components present in bio‐oil. Steam reforming of the two fractions was carried out to investigate the gas product distributions and carbon deposition behavior. Higher H₂ yield and carbon conversion to the gaseous phase can be obtained at relatively low temperature (650 °C) for steam reforming of the light fraction. For steam reforming of the heavy fraction, a higher temperature (800 °C) is necessary to obtain higher H₂ yield and carbon conversion to the gaseous phase. At 800 °C, the heavy fraction requires a higher steam to carbon ratio (10) than that for the light fraction (7) to achieve efficient steam reforming. Based on the same carbon space velocity, for 10 h stream time, the drop of H₂ yield and carbon conversion to the gaseous phase in the steam reforming of the heavy fraction is more rapid than that of the light fraction. Carbon deposition in the steam reforming of the heavy fraction is much more severe than that of the light fraction, as determined by carbon content analysis and SEM detection.     

Experimental investigation of foam performance in the presence of crude oil

The foam performance in the presence of oil plays an important role in foam application in enhancing oil recovery. The present study systematically investigated the effect of oil type, oil content, surfactant type, surfactant concentration, alkane chain length, salinity, and polymer concentration on foam performance in both the absence and presence of oil. The results showed that oil viscosity and oil density as well as oil component all contributed to foam performance in the presence of oil. Within a certain oil content, both light oil and heavy oil had a positive effect on foam, but heavy oil had a higher tendency to stabilize the foam. The order of foam performance by different surfactants was changed by the oil. It is noteworthy that heavy oil is detrimental to sodium dibutyl naphthalene sulfonate (BM) foam. Light oil can improve foam performance while heavy oil can harm foam in some specific cases. Lower salinity, longer alkane chain length, higher surfactant concentration and the presence of a polymer all benefited foam in the presence of crude oil.     

外部因素对稠油乳状液稳定性的影响研究

研究了搅拌速度、搅拌时间以及温度等外部因素对稠油乳状液稳定性的影响。实验表明:随着搅拌时间增加,乳状液分散相平均粒径减小,粒径分布更加均匀,所得乳状液更加稳定;在搅拌作用初期,随着搅拌速度增加,乳状液分散相平均粒径变小,乳状液稳定性增强,但当搅拌速度达到某一值时,乳状液分散相平均粒径不再继续减小反而增加,乳状液稳定性降低;温度越高,乳状液分散相平均粒径越大,乳状液稳定性越差。     

Distinctive combustion stages of single heavy oil droplet under microgravity

This report presents an investigation on the combustion of single droplets comprised of heavy oil and oil mixtures blending diesel light oil (LO) and a heavy oil residue (HOR). The tests were conducted in a microgravity facility that offered 10 s of free-fall time. Fine wire thermocouples supported the droplets, resulting in a measurement of droplet temperature history. Additional data were the droplet and flame size history. The results identified four distinctive burning stages between ignition and extinction for heavy oil (C class) and HOR-LO blends. They are, in succession, the start-up, inner evaporation, thermal decomposition (pyrolysis) and polymerization stages. The start-up stage denoted an initial transient period, where the LO components burned from the droplet surface and the droplet temperature increased rapidly. The latter three stages featured pronounced droplet swellings and contractions caused by fuel evaporation and decomposition inside the droplet. An evaporation temperature demarcated the start-up stage from the inner evaporation stage, and this temperature corresponded to a plateau in the temperature history of the droplet. Two additional temperatures, termed the decomposition and polymerization temperatures, indicated the ends of the evaporation and decomposition stages. These temperatures were similarly identified by plateaus or inflection points in the time-temperature diagram. The evaporation temperature gradually decreased with increasing the initial LO mass fraction in the droplet, whereas the other two temperatures were almost independent of the oil composition. All three temperatures increased with decreasing initial droplet diameter, but the dependence was very slight. Based on the results, the combustion of heavy oil droplets appears to be dominated by a distillation-like vaporization mechanism, because of the rapid mass transport within the droplets caused by the disruptive burning.     

超声波对稠油乳化的影响

超声波会使稠油的组分发生变化,对稠油有一定的降粘作用。超声波作用高含水W/O乳状液在没有乳化剂存在的条件下,能够形成O/W乳状液,这种方式形成的乳状液与加乳化剂转相形成的O/W乳状液相比,稳定性比较差,液滴粒径分布范围变宽,但主要分布范围变窄,液滴分散情况较好。流变性虽然遵循幂律流体规律,非牛顿性有所减弱。从微观观察来分析,在本实验研究范围内,经超声波处理后的高含水W/O乳状液形成的O/W乳状液并非严格意义上的乳状液。     

Microencapsulation of Flaxseed Oil by Spray Drying: Effect of Oil Load and Type of Wall Material

The objective of this work was to evaluate the effect of the type of wall material and the oil load on the microencapsulation of flaxseed oil by spray drying. Gum arabic, whey protein concentrate, and a modified starch were used to produce the microcapsules, each with four oil concentrations (10, 20, 30, and 40% oil, w/w, with respect to total solids), for a total of 12 tests. Initially, the feed emulsions were characterized for stability, viscosity, and droplet size. Then they were dried in a laboratory-scale spray dryer and the resulting particles were analyzed for encapsulation efficiency, lipid oxidation, moisture content, and bulk density. The increase in oil concentration led to the production of emulsions with larger droplets and lower viscosity, which directly affected powder properties, resulting in lower encapsulation efficiency and higher lipid oxidation. Among the three wall materials evaluated, the modified starch showed the best performance, with the highest encapsulation efficiency and lowest peroxide values.     

Diesel Oil Removal by Froth Flotation Under Low Interfacial Tension Conditions I: Foam Characteristics,and Equilibration Time

Abstract

Froth flotation is a surfactant‐based separation process which is suitable for treating dilute wastewaters. To achieve high performance for the froth flotation operation, the combination of an ultra‐low interfacial tension (IFT) between excess oil and excess water phases, high foam production rates, and high stability of the foam produced, must be attained. To obtain the ultra‐low interfacial tensions, a Winsor Type III or middle phase microemulsion has to be formed. In this study, branched alcohol propoxylate sulfate sodium salt with 14–15 carbon number and 4 PO groups (Alfoterra 145–4PO) was used to form microemulsions with diesel oil. From the results of this work, an increase in surfactant concentration decreased the IFT, and increased foam stability. To obtain the minimum IFT in the region of a Winsor Type III microemulsion, the addition of 5 wt.% NaCl was needed. However, this optimum salinity does not result in effective froth flotation due to poor foam characteristics. The results indicate that both the IFT and the foam characteristics should be optimized to achieve high efficiency of oil removal in a froth flotation operation. Unlike the previously‐studied ethylbenzene system, agitation of the solution before introduction into the flotation column yielded the lowest diesel oil removal efficiency because of the poor foam characteristics compared to either unagitated systems or systems allowed to equilibrate for one month.     

油水重力分离过程油滴浮升规律的实验研究

在测定油水重力分离器内分散相油滴的浓度、粒度及中位粒径分布的基础上,分析了各区域内油滴的浮升规律. 结果表明,入口区域油水混合液的湍流程度较大,两相存在较充分的纵向掺混,在100 mm高度以上区域,油相相对浓度均达到0.9以上;斜板和平板区域内油相浓度较高,小油滴聚结成大油滴,在50 mm高度处,中位粒径由10 mm升至30 mm以上;平板区域油膜更新速度较慢,流动性较差,聚结效果不及斜板区域;重力沉降区域内流场相对平稳,油相相对浓度多集中于0.4~0.6之间,大油滴已基本浮升至顶部油层得到分离;隔油板前方区域存在涡旋流,部分区域油相相对浓度约升高了0.02,中位粒径增大了1 mm左右,出现返混现象.     

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.     

Predicting and Controlling the Effect of Solubilized Flavor Oil on Foam Properties of Surfactant through Study of the Adsorption Activity and Configuration

In the wide application of foam products, the effect of oil additive on foam property is a critical issue that has gained increasing attention; the effect on foam induced by various flavor oils is still a puzzling question, and relative study is rare. In this article, a series of typical flavor oils were studied for their effects on the foam properties of sodium dodecylsulfate. Measurements of foamability, foam stability, foam elasticity, and surface activity were taken; meanwhile, molecular dispersion and interfacial arrangement behavior of surfactant and oil molecules were explored by molecular dynamics simulation. Through a combination of macroscopic phenomenon and microscopic information, how flavor oils with different chemical structures affected the foaming properties of surfactants was demonstrated, and an evaluation scheme for predicting the level of influence on foam properties by different flavor oils was constructed. This investigation may help better understand the role of flavor oils in foam systems and provide a theoretical foundation for optimizing the application of flavor oils in relevant industries.     

利用受限空间装置从低浓度水包油乳状液中分离油相的研究(英文)

A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space between the two plates is rather narrow to improve the collisions between oil droplets and the plate surface.Oil droplets have an affinity for the plate surface and thus are captured,and then coalesce onto the surface.The droplet size distribution of the residual emulsion resulted from the separation process is remarkably changed.The oil layer on the plate weakens the further separation of oil droplets from the emulsion.Three types of plate materials,polypropylene(PP),polytetrafluoroethylene(PTFE) and nylon 66,were used.It is found that PP is the best in terms of the oil separation efficiency and nylon 66 is the poorest.The interaction between droplets in the emulsion and plate surface is indicated by the spreading coefficient of oil droplet on the plate in aqueous environment,and the influences of formed oil layer and plate material on the separation efficiency are discussed.     

Influence of the Oil Phase on the Microencapsulation by Complex Coacervation

The influence of oil type on the process yield, efficiency of encapsulation, particle size and morphological aspects of coacervated microparticles was investigated. Firstly, several factors affecting microencapsulation of oils by complex coacervation were simultaneously examined. The results indicated that the process yield is mainly dependent on the velocity of homogenization, temperature and polymer ratio. Using optimum conditions for producing microparticles [pH 4.0, 14,000 rpm, 50 °C, gelatin:gum arabic (GE:GA) 1:1 and 2.5 % w/v], different core materials were tested: a vegetable oil (almond oil), an oil with higher hydrophilic lipophilic balance (vetiver essential oil) and a highly hydrophobic oil (mineral oil). The oil phase exerted an influence on microparticle formation, disturbing the complexation of polymers and modifying the core distribution within the particles. Some of the polymers were complexed when mineral oil was used, and the highest efficiency of encapsulation (91.8 %) was obtained with vetiver oil, followed by the almond (70.6 %) and mineral (38.0 %) oils. Particles produced with vetiver oil were larger (43.5 μm) than those produced with mineral oil (35.0 μm) and almond oil (19.2 μm), and the increase in the size is due to the encapsulation of many small droplets of emulsion, characterizing these particles as multinucleate ones.     

Influence of Processing on the Physical Stability of Multiple Emulsions Containing a Green Solvent

The influence of the emulsification process on the microstructure and physical stability of model water‐in‐oil‐in‐water (W/O/W) emulsions formulated with a green solvent and a mixture of amphiphilic copolymers as emulsifiers was investigated. Emulsions were prepared by applying a homogenization step with a rotor‐stator device followed by high‐pressure homogenization. Viscous flow tests, transmitted light optical microscopy, globule size distribution (GSD), and multiple light scattering (MLS) measurements were carried out. The GSDs obtained were the result of a recoalescence due to overprocessing and the coalescence of inner droplets with the outer water phase. MLS detected a main destabilization mechanism by creaming. The passing of the emulsion through a high‐pressure homogenizer (HPH) significantly delayed the creaming process.     

原油对水相泡沫稳定作用机理研究进展

为了评述原油对水相泡沫稳定性的影响机理,分别介绍了原油在水相泡沫中的存在状态,原油对泡沫的稳定或破坏机理。原油对泡沫的稳定性有着显著影响,稳泡或消泡也极大程度上决定了石油与天然气开采作业中,诸如泡沫驱油、泡沫堵水、堵气、泡沫排液、泡沫压裂等作业效率。重点阐述了假乳液膜对泡沫稳定性的影响机理,总结出原油在水相泡沫体系中以溶解油或乳化油两种状态存在。原油溶解于水相胶束中(溶解油)可降低泡沫的稳定性。大多原油在水相泡沫中以乳化油滴形式存在,油滴与气泡之间被假乳液膜隔开,假乳液膜决定了泡沫体系的稳定性。假乳液膜稳定性好能促进三相泡沫的稳定性;而假乳液膜稳定性差就加剧了三相泡沫地破裂。通过评述指出了原油与水相泡沫相互作用研究领域今后的研究方向。