原油烃指纹GC法在三元复合驱油井分层产能测试中的应用

通过三元复合液与水驱原油作用实验认为,三元复合液对原油烃指纹影响小;通过分层原油配比实验及测试与MFE法分层测试结果对比认为,两种测试方法具有很好的一致性,原油烃指纹色谱测试法适用于三元复合驱油井,为三元复合驱油井分层产能测试及驱油效果监测提供了有效的方法。     

原油乳状液破乳的动态法研究

The stability of different crude oil emulsions from ASP flooding production well is studied by the method of a stirred tank. The demulsifying of crude-oil emulsion by different demulsifying agents is discussed. The breakage of the crude oil emulsions from the well PO11 by the different types and concentrations of the emulsifying agents is also discussed. The breaking mechanism of the demulsifying agent is described microscopically.     

三元复合驱低浓度体系相行为及中间混合层结构分析

低浓度的表面活性剂ASP(碱/表面活性剂/聚合物)驱油体系溶液与模拟原油混合,研究该体系的相行为和界面张力的变化情况,并应用粒度分析仪和冷冻蚀刻透射电子显微镜技术,对中间混合层的粒径分布及其结构进行研究.发现中间混合层的体积随各组分的浓度变化而有一定的规律性,中间混合层与油相和水相之间的界面张力均能达到超低.特别是得到了冷冻蚀刻电子显微镜照片, 并提出中间混合层为胶束、微乳液、乳状液等表面活性剂聚集体的共存体系,其中微乳液结构占主要地位.这对丰富表面活性剂的理论研究及探讨三元复合驱的驱油机理必将起到重要作用.     

破乳剂对复合驱乳状液的破乳机理研究

针对模拟采出液和三元复合驱矿场采出液,研究了破乳剂对复合体系界面张力和膜强度的影响.破乳剂浓度增加,二元复合体系界面张力降低,而三元复合体系界面张力升高.破乳剂分子部分顶替乳化剂分子并显著降低了界面膜强度.     

油/水/表面活性剂所组成分散体系的数学模型

对分散体系的研究,大多采用经验或半经验的方式。例如,表面活性剂的亲水、亲油性平衡值(Hydiophihc-Lipophilic Balance,HLB值),其不确定性使得人们很难利用HLB值来决定某一具体的表面活性剂的实用性;尽管Delichatsios等在研究动力学条件对分散结果的影响时提供了很有价值的关系式,但这类关系式却无法反映动力学条件和表面活性剂在分散体系形成中的关系及重要性,类似的问题在分散体系的研究中相当普遍,且很难满足人们的实际需要,本文尝试在前人研究的基础上,利用分散体系研究中比较成熟的基本概念,用数学方法建立由各量化数学参数所组成的数学模型。     

大庆油田三元复合驱结垢样品中碳酸钙的结晶特性及形貌特征

采用EDAX, XRD和SEM等方法对大庆油田三元复合驱结垢样品中碳酸钙的结晶特性及形貌特征进行了研究. 结果表明, 结垢样品中的碳酸钙呈现出球形、棒状和花状等形貌特征和层状生长的结晶特征. 部分水解聚丙烯酰胺(HPAM)降低了重烷基苯磺酸盐(HABS)表面活性剂的临界胶束浓度(cmc), 促进了其胶束化作用; HABS使溶液中HPAM链的刚性增强, 负电吸引能力增强; 二者均会形成模板, 导致结垢样品中的碳酸钙具有不同的形貌特征. 聚丙烯酰胺和表面活性剂的存在未改变结垢样品中碳酸钙的层状生长特征.     

Triton X-100/甲苯/水三元体系界面张力的耗散颗粒动力学模拟

采用耗散颗粒动力学方法在介观层次上模拟了非离子表面活性剂Triton X-100 在油/水界面上的分布行为, 并把用于油/水二元体系界面张力的计算方法拓展到含表面活性剂的三元体系. 利用该方法可以得到与实验数值吻合的界面张力数据. 另外, 模拟结果直观展示了表面活性剂界面张力与界面密度的关系, 为表面活性剂复配增效理论提供了依据. 该模拟方法给出的微观信息可以为驱油体系配方筛选和表面活性剂有效应用提供指导.     

ASP复合驱油体系瞬时界面张力的研究

以胜利油田孤岛试验区原油为油相,用正交试验筛选了碱/天然混合羧酸盐/聚合物驱油体系,讨论了各组分对ASP复合驱油体系油水瞬时界面张力的影响,并探讨了各组分间的相互作用机理及其在油水界面的吸附机理。     

Evaluation of Water-in-Crude-Oil Emulsion Stability Using Critical Electric Field: Effect of Emulsion Preparation Procedure and Crude Oil Properties

The critical electrical field has been used as a tool to probe water in crude emulsion stability to electrical fields in many previous studies. Given the increasing importance of this metric, this study investigates factors that are important to the reproducibility of the measurement and the effect of emulsion preparation variables on the critical electric field. It was observed that the emulsion preparation procedure has a strong effect on the measured critical electric field due to droplet size effects. Furthermore, the effect of crude oil properties on the critical electric field was investigated using emulsions from different oils but with the same average droplet diameter, where it was found that the measurement was dominated by crude oil viscosity.     

Effect of Crude Oil Fractions on Interfacial Tensions of Novel Sulfobetaine Solutions

The dynamic interfacial tensions (IFTs) of two novel zwitterionic surfactants with different hydrophobic groups, alkyl sulfobetaine (ASB), and xylyl substituted alkyl sulfobetaine (XSB), against kerosene, crude oil, and model oils containing crude oil fractions, such as resins, asphaltenes, saturates, aromatics, and acidic fractions, have been investigated by a spinning drop interfacial tensiometer. The experimental results show that XSB solutions show higher interfacial activity than ASB against kerosene because of the larger size of the hydrophobic part of the XSB molecule. The petroleum acids have high interfacial activity and can adsorb onto the interface. For ASB solutions, the synergism mixed adsorption of betaine and acid molecules lowers IFT values. On the one hand, the partly displacement of XSB molecules by petroleum acid at the interface results in the increase of IFTs. Therefore, resins, aromatics, and acidic fractions show strong effects on IFTs of betaine solutions. On the other hand, asphaltenes and saturates have little effect on interfacial properties. Moreover, the hydrophilic part of the betaine molecule at the interface may vary its orientation from vertical to flat with aging time. Therefore, the dynamic IFT curves of ASB solutions against model oils show “V” shape for resins, aromatics, and acidic fractions.     

Dynamic Stability of Heavy Crude Oil-in-Water Emulsions

The transport of heavy oil as concentrated oil-in-water (O/W) emulsions is one of the most promising pipeline techniques, and how to ensure a steady flow is the key to the successful application of this technology. Most of the previous studies focused on the static stability of the emulsions. However, the stability changes constantly with time and external shearing in the transportation. In this paper, a stable O/W emulsion was prepared for its dynamic stability to be tested by three methods of small-scale flow loop, rheology and stirring, respectively. The results indicated that the O/W emulsion with 30 vol.% water and 0.2 wt.% OP-10 could well satisfy the transport requirement. A critical temperature existed to make the rheological property of the emulsion rapidly deteriorate. For low-Reynolds-number turbulent pipe flow, an appropriate increase of temperatures and shear rates was conducive to the flocculation-dissociation balance of the internal phase, which could effectively reduce the apparent viscosity of the emulsion and the flow frictional resistance. High flow rate of O/W emulsions could be transported at relatively low temperatures to ensure great dynamic stability, and low flow rate of that could be done at relatively high temperatures to obtain low apparent viscosity.     

Stability of Polymer and Surfactant Mixture Enhanced Foams in the Presence of Oil Under Static and Dynamic Conditions

Three different types of foaming agents including hydrocarbon surfactant TQ01, partial fluorinated surfactant BF01, and per-fluorinated surfactant QF01 exhibited good foaming ability and foam stability under 95°C high temperature and 32,325 ppm salinity conditions. The oil-tolerance ability order with respect to Malaysia Off-shore (MOS) crude oil for surfactant TQ01, BF01, and QF01 is TQ01 < BF01 < QF01. Introduction of polymer into the foam formula could significantly increase foam stability. Different polymers show different abilities of increasing foam stability. Spreading coefficient and entering coefficient are close to zero for surfactant BF01 foaming system and much less than zero for surfactant QF01 foaming system, so the oil-resistance ability of foam generated by surfactant QF01 is the strongest. For surfactant TQ01 foaming system, the calculated spreading coefficient and entering coefficient are greater than zero; therefore, the TQ01 foam system is more sensitive to MOS crude oil and its oil-resistance ability is the poorest. Core flooding test indicated that using the 0.4% BF01 and 0.2% YH1096 combined foaming formula could increase the pressure drop across the porous media significantly, indicating that strong foam was generated in the presence of MOS crude oil.     

Effect of Cross Linking Agent on Alkali/Surfactant/Polymer

Alkali/surfactant/polymer (ASP) multisystem flooding technique, which has an expansive application prospect, is one of the enhancing oil recovery (EOR) methods. By adding the organic chromium to the ASP, the molecular structure of polymer was made to change, and the capability of controlling mobility coefficient of ASP was improved. The results showed that multisystem could still keep ultra‐low interfacial tension between the multisystem and crude oil after addition of Cr³⁺. The resistance factor and residual resistance factor, the indicator which describes the capability of controlling mobility, upgraded strikingly. However its storage modulus and loss modulus, the indicator which describes viscoelasticity, increased. The results of physical simulation experiment indicated that this type of improved ASP could increase the recovery ratio by 4.3% compared to common ASP multisystem.     

Effects of a Novel Organic Alkali on the Interfacial Tension and Emulsification Behaviors Between Crude Oil and Water

Experiments have been carried out to investigate the interfacial tension (IFT) and emulsification behaviors between Shengli crude oil and a novel organic alkali (OA). The dynamic IFT and minimum IFT are adopted to characterize the IFT behaviors; the microscopic method, Turbiscan stability index, separated water rate, and laser particle size analysis method are used to show the emulsification behaviors. The dynamic and minimum IFT both decrease continuously with the increase of OA concentration whether surfactant is added or not; because of the synergy of OA and surfactant, the minimum IFT will be reduced to the ultralow value. The synergy is also crucial for the crude oil emulsification. When OA and surfactant are used together, owing to the mosaic and cross-multiple adsorption of OA, surfactant and in situ soap at the interfacial film, the oil can be emulsified more easily, the quantity of emulsified droplets is higher, and the emulsion is more stable with OA concentration increases. The relationship of the minimum IFT and emulsification is investigated; it indicates that the emulsion stability improves, the degree of dispersed homogeneity of oil droplets increases, and the median diameter of emulsified oil droplets decreases with the decline of the minimum IFT.     

New Amphiphilic Ionic Liquids for the Demulsification of Water-in-Heavy Crude Oil Emulsion

This work aimed to use abietic acid (AA), as a widely available natural product, as a precursor for the synthesis of two new amphiphilic ionic liquids (AILs) and apply them as effective demulsifiers for water-in-crude oil (W/O) emulsions. AA was esterified using tetraethylene glycol (TEG) in the presence of p-toluene sulfonic acid (PTSA) as a catalyst obtaining the corresponding ester (AATG). AATG was reacted with 1-vinylimidazole (VIM) throughout the Diels–Alder reaction, forming the corresponding adduct (ATI). Following this, ATI was quaternized using alkyl iodides, ethyl iodide (EI), and hexyl iodide (HI) to obtain the corresponding AILs, ATEI-IL, and ATHI-IL, respectively. The chemical structure, surface activity, thermal stability, and relative solubility number (RSN) were investigated using different techniques. The efficiency of ATEI-IL and ATHI-IL to demulsify W/O emulsions in different crude oil: brine volumetric ratios were evaluated. ATEI-IL and ATHI-IL achieved promising results as demulsifiers. Their demulsification efficiency increased as the brine ratios decreased where their efficiency reached 100% at the crude oil: brine ratio (90:10), even at low concentrations.     

Effect of Aqueous Phase pH on the Dynamic Interfacial Tension of Acidic Crude Oils and Myristic Acid in Dodecane

The time dependence of the interfacial tension between water–acidic crude oil and water–synthetic oil was investigated for aqueous phase pHs ranging from 2 to 9 using the du Noüy ring method at 20°C. Myristic acid in dodecane was selected as a model (synthetic oil) for acidic crude oil containing indigenous surfactants, and the similarities and differences between the dynamic interfacial tension behaviours of the natural and synthetic crude oil systems were compared. The initial interfacial tension and the relaxation of the interfacial tension are sensitive to the aqueous phase pH for both systems. The adsorption kinetics of the indigenous surfactants and myristic acid could be well fitted with the monoexponential model, and the time constants obtained in this manner indicates that reorganization of the indigenous surfactants and myristic acid at the w/o interface are pH dependent. The experimental results also indicate that indigenous surfactants in acidic crude oil and myristic acid in dodecane have similar film formation behaviours at the w/o interface for the range of pHs investigated.     

Interfacial Tension Measurements Between Oil Fractions of a Crude Oil and Aqueous Solutions with Different Ionic Composition and pH

Dynamic and equilibrium interfacial tensions between crude oil fractions and aqueous solutions of various compositions and pH were measured. The basic oil components seemed to determine the interfacial tensions at pH 2, while the non-dissociated and dissociated acidic components governed the interfacial tension at the natural pH and pH 9, respectively. The ionic composition of the aqueous phase influenced the degree of dissociation of the acidic components at pH 9: Na⁺ ions in the aqueous phase promoted dissociation of the interfacial acidic components (compared to pure water), while Ca²⁺ ions resulted in complexation with the dissociated acids and most likely formation of stable interfacial films. The amount of Ca²⁺ determined which of these phenomena that dominated when both ions were present in sea water solutions. Generally, the interfacial tensions of the oil fractions were lower when measured against the high salinity aqueous solutions than against the corresponding low salinity solutions.