Asphaltene deposition during flow through pipes: Parametric and inhibition analyses

Asphaltene deposition is known as one of the problematic topics in petroleum engineering which is caused by changing pressure, temperature, and composition. So it becomes important to investigate the effect of different parameters such as precipitant to oil volume ratio, temperature, and flow rate. For this purpose, flow loop deposition set up was constructed and the pressure drop changes along tube were measured during experimental and this enhancement of pressure drop during the time illustrates deposition occurred. the results showed that increasing precipitant to oil volume ratio and temperature causes increasing deposition and as flow rate increases, the mass of deposits decreases because of increasing the shear rate on the wall of the tube. The novelty of this study is using CTAB and Benzoic acid inhibitors in this flow loop setup. It was observed the CTAB has more impact on inhibition of asphaltene deposition through the tube than a Benzoic acid inhibitor.     

沉淀剂对甲烷在Ce_(0.9)Fe_(0.1)O_2催化剂上催化燃烧反应的影响

分别以NH3·H2O和(NH4)2CO3溶液或两者的混合溶液为沉淀剂制备了Ce0.9Fe0.1O2催化剂,采用X射线衍射、N2吸附-脱附和氢程序升温还原等方法对Ce0.9Fe0.1O2催化剂进行了表征,并考察了Ce0.9Fe0.1O2催化剂对甲烷催化燃烧反应的催化活性。实验结果表明,不同沉淀剂对Ce0.9Fe0.1O2催化剂的甲烷催化燃烧活性、表面性能和还原能力等均有显著影响。以(NH4)2CO3与NH3·H2O的混合溶液为沉淀剂制备的Ce0.9Fe0.1O2催化剂具有较大的比表面积和孔径、较小的粒径和较好的甲烷催化燃烧活性,甲烷的起燃温度和完全转化温度分别为397℃和543℃。催化剂的活性与其比表面积密切相关。     

Self-organization behavior of asphaltene molecules in heavy oils with varying the oil: Precipitant ratio

Ashal’chinskoe and Mordovo-Karmal’skoe crude oils and their components have been studied by thermal analysis and ESR spectroscopy. Directly from the oils as such, two sets of asphaltene fractions (I and II) have been obtained by the two-step addition of 40-fold excess of a precipitant with varying the oil: precipitant ratio in the first step to be 1 : 5, 1 : 10, and 1 : 20. A comprehensive analysis of the results of studying the oils and asphaltene fractions revealed specific features of aggregation of asphaltenes in different oils.     

化学沉淀法处理高浓度含氟废水的研究

采用化学沉淀法处理高浓度含氟废水,考察了沉淀剂用量、沉淀剂配比、溶液pH值、反应温度、搅拌反应时间和静置沉降时间对除氟效果的影响.结果表明,温度在50℃以下,加入n(Ca2+)//n(F-)为2.5的Ca(OH)2乳液,控制pH值为8.0,搅拌反应10min,静置沉降2 h,处理后废水中的氟离子浓度降低至10 mg/L...     

ON THE MASS BALANCE OF ASPHALTENE PRECIPITATION

In the evaluation of experimental data as well as in calculation of phase equilibria the necessity of the application of mass balances is obvious. In the case of asphaltenes the colloidal nature of these compounds may highly affect the mass balance. In the present paper several experiments are performed in order to check the consistency of mass balances within asphaltene precipitation. Asphaltenes are precipitated in two step processes either by changing temperature or by changes in precipitant with increasing precipitation power. This has been performed for three different oils. The data indicates that in temperature experiments as well as in solvent series experiments the precipitation of heavy asphaltenes affects the following precipitation of lighter asphaltenes. In both cases the mass balance using standard separation techniques cannot be closed, as less material is precipitated in a two step process than in the direct process either at low temperature or by direct precipitation with one precipitant. The different fractions were subject to HPLC size exclusion chromtagraphy showing that the material remaining in solution in the stepwise process was of low molecular weight, and that the material in the second precipitation step was often of higher apparent molecular weight and had an increased overall absorbance coefficient.     

ON THE MASS BALANCE OF ASPHALTENE PRECIPITATION

In the evaluation of experimental data as well as in calculation of phase equilibria the necessity of the application of mass balances is obvious. In the case of asphaltenes the colloidal nature of these compounds may highly affect the mass balance. In the present paper several experiments are performed in order to check the consistency of mass balances within asphaltene precipitation. Asphaltenes are precipitated in two step processes either by changing temperature or by changes in precipitant with increasing precipitation power. This has been performed for three different oils. The data indicates that in temperature experiments as well as in solvent series experiments the precipitation of heavy asphaltenes affects the following precipitation of lighter asphaltenes. In both cases the mass balance using standard separation techniques cannot be closed, as less material is precipitated in a two step process than in the direct process either at low temperature or by direct precipitation with one precipitant. The different fractions were subject to HPLC size exclusion chromtagraphy showing that the material remaining in solution in the stepwise process was of low molecular weight, and that the material in the second precipitation step was often of higher apparent molecular weight and had an increased overall absorbance coefficient.     

沉淀剂对甲烷自热重整制氢Ni基催化剂性能的影响

分别以Na2CO3,NaOH和NH4HCO3作为沉淀剂,在pH值为9的沉淀条件下,采用并流沉淀法制备了Ni-Cu/ZrO2-CeO2-Al2O3催化剂,催化剂中Ni负载质量分数为10%。采用XRD、H2-TPR等方法表征了催化剂的结构及还原性能,并考察了不同沉淀剂对甲烷自热重整制氢Ni基催化剂性能的影响。结果表明,在反应温度为650℃~800℃,采用Na2CO3作为沉淀剂制备的催化剂的催化活性及水煤气变换反应的程度明显高于采用NaOH和NH4HCO3作为沉淀剂制备的催化剂,这是由于采用Na2CO3作为淀剂有利于抑制催化剂中非活性组分NiAl2O4尖晶石的形成并改善了CuO的分散性。     

Parametric analysis of the effect of operation parameters on asphaltene deposition: An experimental study

Changing pressure, temperature, and composition cause instability in crude oil and create a problematic issue which is called asphaltene deposition. Asphaltene deposition causes problems in wettability alteration and flow assurance in different parts of petroleum industry so asphaltene deposition becomes a challenging issue in petroleum engineering. Hence, it is necessary to predict asphaltene deposition and investigate parameters which effect on asphaltene deposition. In this contribution, because of similarity between pore throat of reservoir rock and capillary tube, to investigate parameters such as asphaltene content, precipitant ratio, flow rate, and temperature effect on asphaltene deposition, a capillary setup was constructed and a model was developed to relate pressure drop along capillary tube to permeability reduction.     

ASPHALTENE PRECIPITATION AND SOLVENT PROPERTIES OF CRUDE OILS

Improved prediction of the onset of asphaltene precipitation may be achieved using refractive index (RI) to characterize crude oils and their mixtures with precipitants and solvents. Experimental measurements of RI for mixtures of several crude oils with the precipitant n-heptane, are reported at ambient conditions. Theoretical developments are described that will permit extension of these observations to reservoir conditions

Measurements of RJ at the onset of precipitation have shown that the onset occurs at a characteristic RI for each oil/ precipitant combination, supporting the premise that precipitation is dominated by London dispersion interactions and thus, that RI can be used to predict the onset of precipitation. Reports in the literature showing that the onset of precipitation occurs at constant solvent-to-precipitant ratios provide additional confirmation

The theory is developed on the assumption that London dispersion forces dominate aggregation and precipitation of asphaltenes. The interaction energy of asphaltene molecules or aggregates in a medium of oil can be expressed as a function of the difference between the RI of asphaltene and oil. The RI of live crude oil during pressure depletion can be calculated from the RI of the stock tank oil, the molar refraction of the separator gas, the formation volume factor B_o and the solution gas/ oil ratio R_s     

ASPHALTENE PRECIPITATION AND SOLVENT PROPERTIES OF CRUDE OILS

ABSTRACT

Improved prediction of the onset of asphaltene precipitation may be achieved using refractive index (RI) to characterize crude oils and their mixtures with precipitants and solvents. Experimental measurements of RI for mixtures of several crude oils with the precipitant n-heptane, are reported at ambient conditions. Theoretical developments are described that will permit extension of these observations to reservoir conditions

Measurements of RJ at the onset of precipitation have shown that the onset occurs at a characteristic RI for each oil/ precipitant combination, supporting the premise that precipitation is dominated by London dispersion interactions and thus, that RI can be used to predict the onset of precipitation. Reports in the literature showing that the onset of precipitation occurs at constant solvent-to-precipitant ratios provide additional confirmation

The theory is developed on the assumption that London dispersion forces dominate aggregation and precipitation of asphaltenes. The interaction energy of asphaltene molecules or aggregates in a medium of oil can be expressed as a function of the difference between the RI of asphaltene and oil. The RI of live crude oil during pressure depletion can be calculated from the RI of the stock tank oil, the molar refraction of the separator gas, the formation volume factor B_o and the solution gas/ oil ratio R_s