Rheological modeling and drag reduction studies of Indian heavy crude oil in presence of novel surfactant

Viscosity and rheology modeling of heavy crude oil were studied at different shear rate and temperature with and without naturally extracted surfactant Mahua. Drag reduction analysis was done in 2”-ID, 2.5 m horizontal pipeline at different temperatures and flow rates. Viscosity was reduced by 60.4% after addition of 1000 ppm Mahua at 50°C. Modeling analysis showed that crude oil-surfactant samples followed Power law model with high regression coefficients. Maximum drag reduction of 94.8% occurred after adding 2000 ppm Mahua to 85% heavy oil+15% water at 40°C and at a flow rate of 50 LPM.     

Simulation of single phase non-Newtonian flow characteristics of heavy crude oil through horizontal pipelines

The effect of diameter, velocity, and temperature on flow properties of heavy crude oil in three horizontal pipelines using computational fluid dynamics (CFD) was studied. The flow characteristics were simulated by using CFD software, ANSYS Fluent 6.2. The mesh geometry of the pipelines having inner diameter of 1, 1.5, and 2 inch were created by using Gambit 2.4.6. From grid independent study, 221, 365 mesh sizes were selected for simulation. The CFD ANSYS Fluent 6.2 Solver predicted the flow phenomena, pressure, pressure drop, wall shear stress, shear strain rate, and friction factor. A good agreement between experimental and CFD simulated values was obtained.     

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.     

储层条件下的含蜡原油流变性研究

为研究含蜡原油在储层条件下的流变性,应用高压拈度计,在储层压力条件下开展了原油流变性实验。结果表明：在较低的温度条件下,含蜡原油的拈度随剪切速率增大而减小,且起初在一定的剪切速率范围内减幅较大,随后减幅越来越小;随着温度的降低,含蜡原油的表观拈度、拈流活化能及稠度系数增大,非牛顿指数减小,流变特性越来越偏离牛顿流体;采用非牛顿指数、稠度系数、拈流活化能和结构拈度指数等4项参数,能较全面地表征储层条件下含蜡原油的流变性。     

Emulsification of Indian heavy crude oil using a novel surfactant for pipeline transportation

The most economical way to overcome flow assurance problems associated with transportation of heavy crude oil through offshore pipelines is by emulsifying it with water in the presence of a suitable surfactant.In this research,a novel surfactant,tri-triethanolamine monosunflower ester,was synthesized in the laboratory by extracting fatty acids present in sunflower(Helianthus annuus)oil.Synthesized surfactant was used to prepare oil-in-water emulsions of a heavy crude oil from the western oil field of India.After emulsification,a dramatic decrease in pour point as well as viscosity was observed.All the prepared emulsions were found to be flowing even at 1°C.The emulsion developed with 60%oil content and 2wt%surfactant showed a decrease in viscosity of 96%.The stability of the emulsion was investigated at different temperatures,and it was found to be highly stable.The effectiveness of surfactant in emulsifying the heavy oil in water was investigated by measuring the equilibrium interfacial tension(IFT)between the crude oil(diluted)and the aqueous phase along with zeta potential of emulsions.2wt%surfactant decreased IFT by almost nine times that of no surfactant.These results suggested that the synthesized surfactant may be used to prepare a stable oil-in-water emulsion for its transportation through offshore pipelines efficiently.     

轮古15井区含水稠油流变性实验研究

轮古15井区已进入中高含水期,含水稠油的流变性将对降黏举升工艺产生重大影响。通过室内实验,测定了含水稠油在不同温度及剪切速率条件下的剪切应力及黏度,研究了含水率、温度、剪切速率等因素对稠油流变性的影响。研究结果表明,稠油黏度随含水率增大而明显减小,但在高含水率情况下仍需要降黏才能开采;不同含水稠油的流变特性均可用幂律模型加以描述,因此可以用幂律模型对不同产量的稠油井进行不同含水率情况下的黏度计算及预测。     

Synthesis of cyclohexanone-alcohol hemiketals and evaluation as flow improver for waxy crude oil

In this paper, four novel cyclohexanone-alcohol hemiketals (KL-1, KL-2, KL-3, KL-4) as waxy crude oil flow improver have been prepared by cyclohexanone and 1-pentanol, 1-Hexanol, 1-heptanol, 1-octanol. Evaluation results demonstrate the hemiketal compounds have obvious effect on the viscosity and pour point of Henan crude oil. DSC analysis showed that waxing point and waxing peak decreased to a certain degree in 0.05% hemiketal solutions. Wax crystal morphology analysis indicated the four hemiketals played a role of nucleation in the process of waxy crude oil decoagulation, and in that way acts as waxy crude oil flow improver.     

A viscosity bio-reducer for extra-heavy crude oil

Considering that high viscosity of extra-heavy crudes is related to the formation of a dispersed phase of asphaltenes, a dynamic interaction model is proposed which explains the mechanism to achieve viscosity reduction based on the molecular interacting energies between the ester active principle of a viscosity bio-reducer and the asphaltene fraction of crude oil. A qualitative comparison is made between the theoretical and experimental results observed in relation to the rheological behavior of Mexican extra-heavy crudes in the presence of the enhancer. Both, theoretical and experimental data, described a decrease in the asphaltenes dispersed fraction in relation to the ester concentration mainly because of polarity in asphaltenic crudes.     

The effect of cationic surfactant additives on flow properties of crude oil

Pretreatment of the crude oil with flow improver or pour point depressants has received the greatest acceptance due to its simplicity and economy. Three cationic surfactants Bola form based on urea were prepared by quaternization reaction with alkyl dihalides of different chain length (hexayl, decyl-, and dodecyl-dibromide). The prepared compounds (U6, U10, and U12) were evaluated as surface active agents as well as pour point depressant for crude oil compared to monosurfactant (U12a) corresponding to (U12). The surface parameters of each synthesized surfactant were calculated from their surface tension profile including the critical micelle concentration, maximum surface excess (Γ_max), and the minimum surface area (A_min). The free energies of micellization (ΔG°_mic) and adsorption (ΔG°_ads) were also calculated. Its pour point and viscosity decreased significantly after adding surfactants. FTIR studies of crude-surfactant mixture showed remarkable decrease in concentration of viscosity enhancing groups such as alkanes, alcoholic, and acidic groups, indicating the effectiveness of both the surfactants.     

稠油油藏化学驱原油黏度界限数值模拟研究——以胜利油田孤岛东区普通稠油油藏为例

稠油油藏常规注水开发主要面临原油黏度高、储层非均质性强、采收率低等问题。以孤岛油田东区南15-5#站普通稠油油藏化学驱效果为基础,针对胜利油区不同原油黏度油藏条件,与矿场实际动态相结合,建立了化学驱油藏数值模拟模型;通过收集不同原油黏度油藏的高压物性、相渗曲线等开发试验数据,研究不同原油黏度对水驱、化学驱开发效果及注采能力的影响;考虑提高采收率和经济性两方面指标,初步确定适合化学驱的稠油油藏的地下原油黏度界限为500 mPa·s。在合适原油黏度条件下,应用化学驱技术可以提高稠油油藏原油采收率。     

Effect of water content and temperature on the rheological behavior of Caoqiao heavy oil

Due to the high viscosity and the complex fluid characteristics of Caoqiao heavy oil, it is difficult for its exploitation and transportation. In order to effectively develop the Caoqiao heavy oil, the effect of temperature and water content on the rheological properties of heavy oil are experimentally studied. The results show that when the water content is in the range of 0 to 30%, the viscosity of heavy oil first changes little, then increases, and finally decreases with the increase of water content. The water content and temperature have a significant effect on the fluid type of Caoqiao heavy oil. There exists a Newtonian fluid transformation temperature point. When the temperature is higher than the point, the viscosity of heavy oil is basically not affected by the change of shear rate. The higher the water content, the lower the point there is. The temperature of the transformation point is the key factor to ensure the fluidity of Caoqiao heavy oil in the formation and wellbore. The experimental results can provide a directional guide for the efficient extraction and transportation of Caoqiao heavy oil.     

Effective flow improving agents for waxy crude oil

The comb-like copolymer-polyhedral oligomeric silsesquioxane (POSS) nano-composite PPDs, including POA-POSS, POA-VA-POSS, POA-MA-POSS and POA-St-POSS, were first synthesized via in-situ reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by FT-IR, NMR and TGA methods. Subsequently, the effects of the nanocomposite PPDs on rheology of a waxy crude oil were studied. Results showed that POA-VA-POSS is the most efficient PPD among the nanocomposite PPDs, which can depress the pour point, gelation point, apparent viscosity and yield stress of the crude oil to the lowest. Associated with the microstructure of crude oil, the rheo-logical improving mechanisms of the copolymer-POSS nanocomposite PPDs are discussed.     

Viscosity reduction of heavy crude oil by dilution with hydrocarbons obtained via chemical recycling of plastic wastes

The increasing energy demand is persuading oil companies to exploit unconventional reserves of heavy and extra heavy crude oil, which are characterized for their elevated viscosities and upraised production costs. Expensive flow modifiers are often used to lower the viscosity of heavy crude oils so that pipeline transportation becomes viable. In this study, thermal cracking tests were conducted to obtain hydrocarbons (condensate) of lower molar masses, from common plastic wastes. Physical properties of the products were measured, such as viscosity, density, pour point, cloud point and aniline temperature. Due to their chemical similarity, the hydrocarbon products from the tertiary recycling of postconsumer low density polyethylene (LDPE) plastic bags were used to dilute a heavy crude oil (12°API) and lower its viscosity. Results showed a viscosity reduction of 90% at room temperature of a 5:25 vol:vol blend of hydrocarbons/heavy crude oil. This paper proposes an alternative solution for two alarming global problems: waste plastics recovery and optimal transportation of heavy crude oil; However, an industrial application of this process would have to be combined with municipal solid waste collection and pre-treatment technologies.     

An empirical correlation for estimating the viscosity of non-Newtonian waxy crude oils

Non-Newtonian fluids are the most complex ones when it comes to predicting their flow behavior. In the pre-existing models, rheological behavior in waxy crude oils is mainly affected by shear rate and thermal history of crude oils. In the present work, rheological characteristics of four different crude oils were studied by coaxial cylindrical rheometer at three different temperatures (40°C, 50°C, and 60°C) and a model was proposed keeping into consideration wax content for the first time. This model is prepared to predict the viscosity of four different crude oils with different wax content and at different temperature. The proposed model can efficiently estimate the viscosity as compared to other established models.     

非牛顿原油包水乳状液的表观黏度预测

基于有效介质理论,在Pal等学者提出的经典黏度模型基础上,对含沥青质、胶质等界面活性成分的原油包水乳状液黏度及流变特性进行预测。界面活性分子对连续相的吸附与夹带,导致有效含水率的增加,是乳状液具有非牛顿性的诱因。将促进与阻碍乳状液有效含水率增加的正反2种作用分开考虑,并用含水率因子和颗粒雷诺数因子分别表征。含水率因子考虑了含水率及微观液滴分布对促进作用的影响;颗粒雷诺数因子着重体现不同液滴微观分布时剪切的破坏作用。建立了考虑微观液滴分布、剪切速率、含水率等多因素影响的黏度预测模型,油田现场原油、矿化水乳状液数据验证表明,所建模型具有较好的预测精度,预测结果的最大相对误差为11.44%。     

Improvement of rheological properties of Algeria crude oil by addition of extra-light crude oil and a surfactant agent

Abstract

Effect of surfactant and extra-light crude oil addition on the rheological behaviors of an Algeria crude oil in order to improving its flowability were studied at low temperature. These rheological properties include steady flow behavior, yield stress and viscoelastic behavior. An AR-2000 rheometer was employed in all of the rheological examination tests. Results show that Toluene and extra-light crude oil addition causes a strong reduction in viscosity, the yield stress and can effectively increase of crude oil transport capacity. The toluene addition gets its best flow capacity and lowest viscosity at 6%. The extra-light crude oil addition obtains its best flow capacity and lowest viscosity at 50%. The viscoelasticity character of the crude oil has indicate a significantly influence by the addition of Toluene and extra-light crude oil.     

Effect of reaction temperature and hydrogen donor on the Ni0@graphene-catalyzed viscosity reduction of extra heavy crude oil

Ni⁰@graphene nanocomposites were prepared via a solvothermal method and used as the catalysts for the viscosity reduction of extra heavy crude oil. Higher graphene content in Ni⁰@graphene nanocomposite has an adverse effect on its catalytic activity. The addition of tetralin and higher reaction temperature can obviously promote the catalytic activity. The catalyst accompanied by hydrogen donor can attain a viscosity reduction rate of 84.3% after the catalytic reaction under 280°C for 24 h and reduce the viscosity of crude oil from 174,219 to 27,352 mPa s (measured at 50°C).     

牙哈原油综合评价

介绍了对牙哈原油进行的综合评价。结果表明:该原油的特点是密度小(849.9 kg/m3),轻质油收率高,且质量好,初馏点～145℃馏分是理想的重整原料,初馏点～180℃是较理想的汽油调合组分,也是优良的乙烯裂解原料,初馏点～350℃收率72.17%,加工时应严格控制比例,比例过高,常压塔的汽相负荷大,会影响常减压装置的稳定操作和安全生产。牙哈原油重整原料的收率较高,砷、氯,硫含量低,腐蚀合格。牙哈原油芳烃潜含量较高,重整加工时芳烃收率指数高达73.51%,是较理想的重整原料。牙哈原油喷气燃料组分加工前应针对碱性氮小的情况采取白土精制,保证航空煤油颜色的稳定性。240～300℃,300～350℃两段组分是较理想的柴油馏分,但必须经过加氢或碱洗精制,240～300℃是调合低凝柴油的优质组分。其减压蜡油作为润滑油馏分粘度指数大,黏温性能好,酸值小,芳烃含量较低,适合作生产高黏度指数润滑油的基础油,也是较好的催化裂解原料,大于520℃的减压渣油收率低,应与其他渣油掺炼,没有单独深加工的必要。     

高压含气条件下含蜡原油析蜡点测量方法

针对常规方法只能测量地面脱气油的析蜡点,不能测量高压含气条件(油藏条件)下含蜡原油析蜡点的不足,提出了以Arrhenius方程为理论基础,利用高压毛细管黏度计测量高压含气条件下含蜡原油析蜡点的方法。实验结果表明,实验油样地面脱气后析蜡点为63.74℃,油藏条件下析蜡点为59.73℃,含蜡原油地面脱气后更容易析蜡。建议采用油藏条件下的析蜡点作为注水设计参数。     

ZC-11型原油阻降粘剂的工业应用

某单位加工的原油以涠洲、陆丰、西江等海洋油品为主,油品性质复杂,原油中的重质组分易在储罐底部沉积,随着生产周期的增长,罐底积累的油渣造成原油罐区有效库容下降、输送泵故障频发及检修清罐损失等生产难题.企业联合科研院所开发了1种用于防止原油沉降、降低原油粘度、凝固点的阻降粘剂(ZC-11型),工业应用表明,在正常工况下,该...