Aminated Copolymers as Flow Improvers for Super-viscous Crude Oils

The new flow improvers for super-viscous crude oils were developed via esterification of polybasic high carbon alcohol with methacrylate and copolymerizafion of monomers followed by amination of copolymers. The structure of the synthesized polymer flow improver additive was confirmed by IR spectroscopy and the crystal structure of the flow improver additives were determined by X-ray diffrac- tion analysis. The structure of wax crystals was also studied at the same time. The results showed that the wax crystal structure was closely related with the crystal structure of the flow improver, which could change the pour point depression and viscosity reduction behavior of the crude oil. When the wax crystal structure matched well with that of the additive, the wax crystals were dispersed satisfactorily, resulting in favorable effects in terms of pour point depression and viscosity reduction. The new synthe- sized aminated polymer flow improver additive was most efficient for treating super-viscous crude oils. The super-viscous crude oil had a high content of resins and asphaltenes, which might aggregate onto the surface of wax crystals to form blocks to limit the crude oil fluidity. However, amination of copolymers having similar structure with the resins and asphaltenes contained in crude oil could dissolve the huge polar groups to make the deposit formation difficult.     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART II EFFECT OF WAX COMPOSITION AND CONCENTRATION ON THE DEW AXED CRUDE OILS WITH / WITHOUT ADDITIVES

ABSTRACT

In this part of the work the effect of wax concentrations on the rheologica! properties of the dewaxed Duliajan (Assam) and Lingaia crude oils have been studied. The dewaxing of the crude oil was done by removing n-paraffins from the crude oil by urea adduction. The urea adducted n-paraffins concentrate-the wax- was characterized by its carbon number distribution. The urea non adducted oil portion - the denormalized crude oil (DNO)- was characterized for its pour point. The wax in different concentration was then added in the DNO and the change in the rheological properties like pour point, yield stress and plastic viscosity were studied using a Haake Rota Viscometer. The effect of carbon number distribution, i.e. the composition of the wax, on these rheological properties was also investigated. Four different commercial pour point depressanl additives have been used to study their effects on the pour point, yield stress and plastic viscosity of the reconstituted (wax mixed DNO) crude oils.

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point of the DNO, and the DNO composition has a small effect. However, as seen in the Part I of this paper, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the composition of the DNO. The additives have shown better response in the DNO having more aromatic concentrate, as has been found in the case of Duliajan (Assam) DNO.     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART II EFFECT OF WAX COMPOSITION AND CONCENTRATION ON THE DEW AXED CRUDE OILS WITH / WITHOUT ADDITIVES

In this part of the work the effect of wax concentrations on the rheologica! properties of the dewaxed Duliajan (Assam) and Lingaia crude oils have been studied. The dewaxing of the crude oil was done by removing n-paraffins from the crude oil by urea adduction. The urea adducted n-paraffins concentrate-the wax- was characterized by its carbon number distribution. The urea non adducted oil portion - the denormalized crude oil (DNO)- was characterized for its pour point. The wax in different concentration was then added in the DNO and the change in the rheological properties like pour point, yield stress and plastic viscosity were studied using a Haake Rota Viscometer. The effect of carbon number distribution, i.e. the composition of the wax, on these rheological properties was also investigated. Four different commercial pour point depressanl additives have been used to study their effects on the pour point, yield stress and plastic viscosity of the reconstituted (wax mixed DNO) crude oils.

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point of the DNO, and the DNO composition has a small effect. However, as seen in the Part I of this paper, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the composition of the DNO. The additives have shown better response in the DNO having more aromatic concentrate, as has been found in the case of Duliajan (Assam) DNO.     

Wax Deposition in Flow Lines Under Dynamic Conditions

The wax deposition in the tubing, pipeline, and surface flow line is the major problem in the oil fields. It generates additional pressure drop and causes fauling and ultimately increases the operating cost during production, transportation, and handling of waxy crude oil. In this work, attempts were made to study the wax deposition in the flow lines due to Indian crude oil under dynamic condition. The experimental work was carried out for neat crude oil and pour point depressants treated crude oil at different ambient/surface temperature and pumping/reservoir temperature. It was observed that temperature has significant effect on the wax deposition of the crude oils. From these studies, ideal temperature of crude oil to pump in the pipeline or flow line was determined. The present investigations also furnishes that the selected pour point depressant in this work decreases the wax deposition significantly and may be used for controlling the wax deposition problems in case of Indian crude oil.     

甲基丙烯酸十八酯-顺丁烯二酸酐-醋酸乙烯酯-苯乙烯降凝剂对原油蜡晶形态的影响

用偏光显微镜(PLM)观察甲基丙烯酸十八酯-顺丁烯二酸酐-醋酸乙烯酯-苯乙烯(OMVS)降凝剂添加量对原油蜡晶形态的影响。实验结果表明,随OMVS降凝剂添加量的增加,蜡晶由不规则的棒状和片状逐渐变为粒径小、分散均匀的近似球状的蜡晶;PLM表征结果显示,加入OMVS降凝剂的非洲原油和国产原油的蜡晶颗粒数均由不到100个增至大于1300个和1700个,原先占主导地位的表面积较大(非洲原油150～250μm2和国产原油100～200μm2)的蜡晶个数由超过60%降至1%以内,表面积较小(5～50μm2)的蜡晶个数由不到10%增至90%以上。通过指数回归可确定OMVS降凝剂添加量-蜡晶平均表面积-降凝幅度的内在关系,计算结果与实验结果吻合。     

A Study on the Interaction of Crude Oil Waxes With Polyacrylate Pour Point Depressants by Monte Carlo Simulation

The interaction of crude oil waxes with polyacrylate pour point depressants (PPDs) bearing different structures was investigated in detail by Monte Carlo simulation, using n-hexadecane as representative component of wax crystal. It was demonstrated that during wax precipitation the mixed energy was low when the side chain length of polyacrylate was close to that of n-hexadecane. Meanwhile, the mixed energy between polyacrylate PPDs and n-hexadecane was shown to be closely related with the polarity of building blocks of polyacrylate. Our results indicated that it is easier for polyacrylate polymers with polar building blocks to interact with n-alkanes, which would effectively inhibit wax-crystal precipitation and improve crude oil low-temperature fluidity. The simulation results provide with some knowledge for guiding the molecular design and synthesis of polyacrylate PPDs.     

Study on Commercial Pour Point Depressants Lowering Cold Filter Plugging Point for Daqing Diesel Fuels

Ethylene-vinyl acetate copolymer is widely used as commercial pour point depressants (PPDs) all over the world. The authors describe four commercial PPDs for evaluating the sensitivity of Daqing diesel fuels. The content and carbon number distribution of n-alkanes in the Daqing diesel fuels were analyzed by high-temperature gas-phase chromatography. The structures of the commercial PPDs were confirmed by IR spectra. The results indicate that the n-alkanes carbon distributions display an obvious normal distribution in the Daqing diesel fuels. Commercial PPDs can maximumly depress cold filter plugging point of the tested diesel samples by 7°C, 3°C, 5°C, and 0°C, respectively. The distributions of high carbon n-alkanes are all narrow so that wax crystals precipitate more easily at low temperatures, and as a result, the interaction between PPD molecules and wax crystal molecules is not good.     

Evaluation of Effect of Polymeric Pour Point Depressant Additives on Indian Waxy Crude Oil

Abstract

Wax deposition in oil production constitutes a critical and difficult-to-control problem in terms of productivity and production operation costs going from the reservoir to surface facilities. In the present work, four polymeric additives were prepared and used as pour point depressants (PPD) for Limbodara (Indian) crude oil via polymerization of different undecylenates with maleic anhydride with a further reaction with amine. The results are encouraging and show that prepared additives function both as wax dispersants and flow improvers due to the presence of polar groups in the structure. Cross–polarizing microscopic studies were performed to study changes in morphology of wax crystals in crude oil with and without additive. A zero-friction advanced rheometer AR-500 was used to determine the viscosity by applying Bingham plastic-flow model.     

Characteristic Temperatures of Waxy Crude Oils

Gel point or pour point is widely used to evaluate the low temperature flowability of crude oil. However, it is not adequate to describe the gelling properties of waxy crude oils under flow conditions with gel point or pour point, since the rheological behavior of crude oils is dependent on shear history. Waxy crude oils tend to gel at a low temperature. Based on gelation theory, the characteristic temperature of waxy crude oil was determined by analyzing viscosity-temperature data. Two mathematical models were developed for calculating characteristic temperatures of virgin crude oils and pour point depressants (PPD) beneficiated crude oils, respectively. By using these two models, the characteristic temperatures of crude oils that have experienced shearing and thermal histories can be predicted. The model for predicting the characteristic temperature of virgin crude oils has an average relative deviation of 4.5%, and all predicted values have a deviation within 2 ℃. Tested by 42 sets of data, the prediction model for crude oil treated with PPD has a high accuracy, with an average relative deviation of 4.2%, and 95.2 percent of predicted values have a deviation within 2 ℃. These two models provide useful ways for predicting the flowability of crude oils in pipelines when only wax content, wax appearance point and gel point are available.     

The use of bio-diesel based additive as rheology improver and pour point depressant of Nigerian waxy crude

The chemical method has proved to be the most effective mitigating method of wax deposition in petroleum system as it deals with the root cause of wax formation. Most of the commercial chemicals in the industry are very expensive and toxic. This paper aims the use of biodiesel based additives for improving the rheological behavior and pour points of waxy crude from Nigeria field. The biodiesels derived additives gave better performance than the commercial chemical and the seed oils as greatly improvement in rheology and pour point values of the waxy crude were observed     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART I WITH AND WITHOUT POUR POINT DEPRESSANT ADDITIVES

The yield stress, plastic viscosity and apparent viscosity and the dependence of the latter on the shear rate have been studied at different temperatures below pour point of Lingala (Krishna-Godavari basin, Eastern coast), Duliajan (Eastern region of Assam), Rava (Godavari basin) and Bombay-High (off-shore western region) indigenous crude oils

Four different commercial pour point depressant additives have been used to study their effects on the pour point, yield stress and plastic viscosity

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point, and crude base composition has a small effect. However, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the liquid matrix. As the temperature is lowered both the yield stress and plastic viscosity increase in case of each crude oil. However, the magnitude is dependent on the nature of the crude oil. With pour point depressant additives, the yield stress and plastic viscosity are decreased and this decrease is a function of nature of the liquid matrix of the crude oil and concentration of the additive     

Nano-composite pour point depressants in improving the rheology of waxy crude oil

This article mainly describes the advantages of nano-pour point depressants on the low-temperature fluidity of crude oil compared with traditional pour point depressants. The common nano-pour point depressants are mainly divided blend type and polymerization type. It can effectively improve wax crystal structure and strength, thereby improving the low-temperature fluidity of crude oil. Nano-particles have better application prospects in improving rheological properties of waxy crude oil.     

聚醚酰胺的合成及其对原油流动性的影响

以聚醚酰胺和脂肪酸为原料合成了系列脂肪酸聚醚酰胺降凝剂,利用FTIR、黏度测试、界面张力测试等方法考察了降凝剂对不同原油流动性的影响.实验结果表明,该系列降凝剂具有较好的表面活性和界面活性.随碳数的增加,饱和脂肪酸聚醚酰胺降凝剂降低表面张力的能力增强.加入0.3％(w)和0.9％(w)的棕榈酸聚醚酰胺降凝剂时,风城原油...     

胺解聚合物型原油降凝剂的合成及应用

通过丙烯酸高碳酯与马来酸酐、醋酸乙烯酯、苯乙烯共聚后进行不同系列胺解得到一系列新型高蜡原油降凝剂。考察了该类降凝剂对大庆高蜡原油和尼尔阿曼混合原油的降凝效果。结果表明，胺解聚合物型原油降凝剂具有较好的原油降凝性能，降凝幅度最高达到27℃；同时，测定了加剂温度对降凝剂降凝效果的影响，结果发现，当加剂温度高于原油析蜡温度时，降凝剂的降凝效果才能充分显现出来。     

丙烯酸十八酯-苯乙烯共聚物对含蜡原油改性效果与分子动力学模拟

合成了单体配比不同的丙烯酸十八酯-苯乙烯共聚物(OAS)降凝剂,采用实验与分子动力学模拟相结合的方法对降凝剂的性能进行评价.实验结果表明,OAS降凝剂的降凝减黏性能随丙烯酸十八酯比例的增加呈现出先增大后减小的趋势.在2000 mg/kg加剂量下,苯乙烯与丙烯酸十八酯摩尔比为1:3的降凝剂OAS-4能使含蜡原油凝点降低4...     

聚合物/微纳米复合含蜡原油降凝剂的研究进展

含蜡原油中蜡分子的结晶析出会使原油的低温流变性显著恶化,降低原油管输的安全性和经济性.添加少量的聚合物型降凝剂能够改变蜡分子的结晶习性,改善原油的宏观流动性.加降凝剂原油的凝点越低、低温黏度越小,意味着输送的能耗越低、安全性越高,因此人们对原油降凝剂的降凝降黏效果追求是无止境的.利用不同的微纳米颗粒,研制高效的聚合物/...     

聚合物型原油降凝剂的结晶性能研究

摘要: 采用红外光谱仪、核磁共振波谱仪对聚合物的合成特征基团进行了表征，并采用X射线衍射仪对不同型号蜡及降凝剂的结晶性能进行了分析测试，结果表明蜡晶与聚合物的结晶性能密切相关，结晶度不同，蜡晶分散效果不同，对原油降凝性能也就有所区别，当两者结晶性能状态匹配时蜡晶分散效果变好，降凝降粘性能最佳，并通过考察原油体系热性能和低温流动性能进行了证实。     

原油降凝剂的研制与初步应用试验

合成了两个系列的原油降凝剂 ,一个是丙烯酸高碳醇酯和马来酸酐共聚 ,然后用高级脂肪胺胺解 ;另一个是 α 烯烃和马来酸酐共聚 ,然后用高级脂肪胺胺解。添加 1 0 0× 1 0 - 6的此类降凝剂于大庆原油中 ,结合热处理 ,可降低凝固点 1 9～ 2 2℃。讨论了原油的性质、降凝剂的结构及试验条件对降凝效果的影响。加入 1 0 0×1 0 - 6试样到辽河、任丘、新疆、和大庆原油中 ,也有较好的降凝作用 ,表明这些共聚物是适合于高蜡原油的降凝剂     

柴油对乙烯-醋酸乙烯酯降凝剂感受性的研究

用色-质联用方法对经纯化处理的4种国内外柴油降凝剂进行分析,确定了它们纯化后所得聚合物均为乙烯-醋酸乙烯酯。对柴油组分及其调合柴油进行降凝剂感受性试验,结果表明,乙烯-醋酸乙烯酯降凝剂对柴油具有较好的降凝效果,对加氢柴油及其调合柴油具有较好的降低冷滤点效果,当加剂量为500 ?g/g时,加入降凝剂B能使加氢柴油的冷滤点降低12 ℃,加入降凝剂C可使-20号调合柴油的冷滤点降低20 ℃。分析柴油的正构烷烃含量及其碳数分布,结果表明,正构烷烃含量低且具有较高含量低碳数正构烷烃柴油的低温性质较好;正构烷烃含量低、碳数分布宽、含有少量高碳数正构烷烃的柴油的加剂感受性较好。     

高凝原油降凝剂的合成及复配性能研究

根据高凝原油组成以及降凝剂对原油的感受性确定了合成降凝剂的高碳醇的碳数,以丙烯酸和C18～C22混合醇为原料,合成丙烯酸高碳醇酯,得到三种聚合物:丙烯酸酯自聚物(AM),丙烯酸酯-醋酸乙烯酯(AMV)和丙烯酸酯-醋酸乙烯酯-苯乙烯(AVS)。比较了三种聚合物的降凝效果,选出AVS考察其合成条件并且与常用降凝剂EVA进行复配。实验结果表明:丙烯酸酯、醋酸乙烯酯、苯乙烯最佳配比为1∶1∶0.5,引发剂用量为1.2%,单体质量浓度30%,反应时间为7h时,三元共聚物AVS与EVA的复配物CPR可以使魏岗原油凝固点降低10℃,防蜡率达到40.62%。