جستجوی مقالات مرتبط با کلیدواژه « رسوب آسفالتین » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Low-salinity or engineered salinity waterflooding is one of the enhanced oil recovery methods, particularly for the carbonate fields in Iran and around the world. Alongside its numerous benefits, evaluating the side effects such as formation damage due to asphaltene instability and deposition is of paramount importance. Until now, research in this area has primarily focused on the investigation of oil-brine interactions, neglecting the influence of the presence of rock as an essential parameter. Therefore, in this paper, to bring the laboratory tests closer to reservoir conditions, the effect of rock presence was examined by creating contact between brine/fluid/sandstone grains and measuring the UV absorption of bulk oil before and after contact with rock and brine. In this regard, a new “indirect” procedure was developed through which the amount of asphaltene deposition in the presence of various brines was determined. Our results indicate that asphaltene deposition follows a non-monotonic trend with salinity, such that it increases at low salinities and decreases at high salinities, and reaches a minimum value at a middle salinity. The results also show that in the presence of two times diluted seawater, more asphaltene deposition occurs compared to other brines. Adding sandstone particles to the oil-brine system increases the amount of asphaltene deposition due to the creation of a new physical surface for asphaltene adsorption due to the influence of electrostatic forces. Detailed examination of the sand particles reveals that the higher the brine salinity, the higher the asphaltene deposition occurs on the particles; with formation brine leading to the highest asphaltene deposition on the particles (over 1.4 micrograms per gram sand). Ultimately, these experimental results contribute to the understanding of the role of sandstone particles on asphaltene instability during low-salinity waterflooding and provide a more accurate way of evaluating asphaltene deposition at more realistic conditions.

In this research, the possibility of asphaltene separation from the vacuum tower residue using the low cost industrial solvents such as 402, 404, 406, and 410 was investigated. In order to separate asphaltene the IP143/01 and ASTM D 3279-07 separation methods were utilized. In order to find the optimal state of asphaltene precipitation, Design of experiments software with three factors of residence time, the solvent-to-feed ratio and the volume percent of 406 solvent to the total solvent of 406 and 410 were used. The results showed that the effectiveness of each parameter in precipitating the asphaltene attributed to the ratio of solvent to feed, the ratio of solvent 406 to total solvent, and the residence time, respectively and there was a significant interaction between the basic parameters. The best asphaltene precipitation of 5.06% of 7.5% happens at the residence time of 36.97 hours, the ratio of solvent to feed of 35.95 ml/gr and the volume percent of 406 solvent to the total solvent of 27.20%. Asphaltene precipitation percentage for the optimal mixture of industrial solvents was 22.5% lower than the precipitated asphaltene from normal heptane solvent. However, according to the solvents price, industrial solvents (410 and 406) were approximately 50% cheaper than normal heptane, and hence on overall, there was a cost savings of more than 20%

One of the most promising methods in order to mitigate asphaltene precipitation is to use asphaltene dispersants. In this study, the effect of two dispersants of toluene and dodecylbenzene sulfonic acid on asphaltene precipitation of a dead and a live oil sample has been investigated. Investigations on dead oil were conducted using IP143 standard test and for studying live oil in the presence of asphaltene dispersants high pressure microscopy was used. The obtained pictures from high pressure microscopy were analyzed using a picture analysis software. According to the results, this dispersants in dead oil create an optimum point for asphaltene precipitation. In live oil, this dispersants reduce asphaltene precipitation; moreover, for dodecylbenzene sulfonic acid, the reduction in asphaltene precipitation reaches down to 70 percent. Also, it was observed that in the effect of injection of these dispersants, the average size of asphaltene flocculation has reduced, which this reduction was much more for dodecylbenzene sulfonic acid in comparison with toluene.

Asphaltene deposition is one of the main problems in crude oil production. Using of asphaltene dispersants and inhibitors are one of the effective methods for preventing deposition of asphaltene particles. Acids are an important class of chemical compounds that could reduce asphaltene problems, regarding to the polarity of asphaltenes and acid molecules. Their efficiency is related to the amount of asphaltene-acid interaction. In this study, the amount of the interaction of acids and their binary mixtures was studied with extracted asphaltene from Iran crude oil by using UV-vis spectroscopy. Different acids were examined that included mono and multi-functional acids. In this method, decreasing the UV absorbance was assisted as index for the amount of the interaction of acids with asphaltene in the asphaltene-toluene solution with the presence of aqueous solution of acids and their binary mixtures. Solubility performance of acids and their binary mixtures was compared for reducing the amount of asphaltene precipitation by changing their mole volume. Experimental results show that the interaction of asphaltene-acids increases with increasing the amount of acid. Among the all studied acids, Interactions of adipic acid and oxalic acid with asphaltene are more than of other acids. The effect of acids binary mixture also investigated on asphaltene precipitation. Results of experiments show that the binary mixtures which is containing para-toluene sulfonic acid has the most interaction with asphaltene particles to reduce amount of precipitation.

Among various methods available for chemical enhanced oil recovery, alkaline injection has great potential for production of heavy acidic crudes from oil reservoirs. Through the reaction with acidic components of crude oil, caustic solution reduces the interfacial tension of different existing phases which leads to higher oil production. Besides, asphaltene deposition is a major problem during the production and exploitation from heavy oil reservoirs. The inhibition of asphaltene deposition and proposing a suitable amendatory solution in case of deposition occurrence are significantly important. In this study, the efficiency of alkaline injection on the recovery of crude and synthetic oil solutions was investigated using two different glass micromodels, (i.e. homogeneous and heterogeneous). Furthermore, the effect of alkaline injection in the case of the presence of precipitated asphaltene due to heptane injection was visually observed. Experimental results showed that in crude oils and synthetic solutions, whenever no asphaltene was precipitated, alkaline injection was effective but after asphaltene precipitation, alkaline injection did not have any considerable impacts on oil recovery. The results also demonstrated and authenticated that alkali flooding can alter micromodel wettability in some parts of the model. This wettability alteration mechanism eventually results on enhanced oil recovery.

Formation of asphaltene deposition in reservoirs during primary production and enhanced oil recovery techniques; such as, gas injection, especially carbon dioxide, is a devastating problem which occurs in many oil fields in the world. The experimental studies to predict the formation of asphaltene precipitation to be necessary to avoid possible irreparable problems resulting from its formation in the reservoir and eventually it will provide access to the best recovery efficiency. As a result of the technical and economic importance and the necessity of studying and understanding the operating conditions of the formation of asphaltene deposition in reservoirs is inevitable. In this paper, the thermodynamic behavior of fluids in oil processing unit has been studied at Sahand University of Oil and Gas Research Institute, which has the capability of testing high temperatures and pressures. The amount of asphaltene precipitation has initially been saturated by the injection of carbon dioxide into the porous media (sand pack), and then the amount of asphaltene precipitation pressurized with oil sample, at constant pressure and temperature, but various residence times. And then to investigate the effect of temperature and pressure and Oil composition at residence time, respectively, the test is repeated at lower temperature and higher pressure and oil change from Asmari reservoir oil to Paydarshrq oil reservoir. At a constant temperature and pressure with an increase in the residence time, more of asphaltene deposition has been formed on filter paper. At higher pressures and lower temperatures, and changing the oil samples also increased the amount of asphaltene with increasing residence time.

Asphaltene precipitation from reservoir fluids during oil production is a serious problem resulting in plugging of the formation, wellbore and production facilities. Generally, asphaltene precipitation has only been investigated from thermodynamic approach in literature, and it assumed that precipitation is relatively fast and has no kinetik effects. Without a good understanding of the associated kinetic effects during the precipitation of asphaltenes, the thermodynamic models can provide misleading predictions for asphaltene stability. So, it should be analyzed from two points of view, thermodynamic and kinetics stability. In this study a molar rich gas and CO2 programmed titration technique was used to evaluate the kinetics of gas-induced asphaltene precipitation from Iranian reservoir oil under isothermal and isobaric initial reservoir conditions in a solids detection system (SDS) and with kinetics of polymerization assumption for reaction between asphaltene and gas, the kinetics parameters of reaction is determined. The results show that asphaltene precipitation occurs in 0.9 mol of rich gas and 0.3 mol of CO2 injected per one mol of reservoir oil. Also, the reaction order of CO2 & rich gas is 2.7 times more than reaction order of asphaltene. So in gas injection, the rate of asphaltene precipitation is highly dependant to the volume of gas.

Precipitation and deposition of asphaltene are one of the serious problems in oil industry and has drawn the attention of many researchers in recent decades. The application of aromatic solvents is the most common method of asphaltene removal, especially in oil wells. Xylene, one of most applicable aromatic solvents, creates many environmental issues. Then it is needed to reduce the use of xylene either by co-solvents or replace it with environmentally friendly solvents. The main purpose of this paper is to find an alternative solvent to replace or reduce consumption of aromatic solvents. Firstly, the efficiency of xylene has been evaluated in the presence of co-solvents including kerosene and diesel at different temperatures. Then, terpene as an environment-friendly asphaltene solvent has been studied at ambient temperature and 80 ⁰C. The results show that efficiency of xylene in the presence of kerosene is higher than diesel. Moreover, temperature increase leads to more asphaltene dissolution. Finally, terpene has shown an acceptable solubility compared to aromatic solvents while its efficiency is being reduced dramatically in the presence of kerosene and diesel.

Organic deposits particularly, asphaltenes cause detrimental effect on the petroleum industry, because it causes to decreases produced oil and clogging the oil facilities. Generally, dispersants and inhibitors or asphaltene solvents are using for chemical controlling of asphaltene precipitation. The asphaltenes content in crude oil are stable under the certain conditions, but there is no certainty about the stability of system in another operational condition. So it is important to study the kinetics of asphaltene settling and deposition. In this work, we investigated the kinetics effect of the three dispersants on the stability of asphaltene aggregates using turbidity measurement and particle size distribution methods. Turbidity measurement showed as the dispersant strength rises;moreover, the turbidity of unstable sample containing dispersant less declines versus time. Asphaltene particle size distribution measurements showed that adding dispersant decrease the average diameter of asphaltene aggregates. Also, in this study the kinetics of asphaltene settling using power law model and the relations of the diluted suspensions was developed. The result of model showed the settling velocity of asphaltene has been decreased by adding dispersants.

One of important processes in petroleum industry is asphaltene extraction from crude oil using light alkane solvents. In this work, asphaltene precipitation in crude oil during alkane solvent titration has been studied. Also, PC-SAFT, Flory- Huggins and Solid models have been investigated to account the amount of asphaltene extraction from crude oil using light alkane solvents during deasphaltene processes. After mathematical formulation of these models, the tuning parameters were adjusted. In order to compare the performance of studied models, the amount of asphaltene extraction from crude oil using light alkane solvents. experimental data reported in the literature were correlated using deviation of the predicted asphaltene precipitation amount from their experimental results. The results show that the PC-SAFT EOS correlates more accurately the experimental results over a wide composition interval with deviation of 4.05 to 6.17% whereas modeling based on the Solid model is less accurate with deviation 10.03 to 21.3%.

In this paper، two models، namely the Flory-Huggins (polymer) solutions theory and the model developed by Rassamdana and co-workers، which served as our basic model، were employed for estimating asphaltene precipitation. In the analyses، the asphaltene solubility parameter was initially considered as a function of pressure and was subsequently adjusted by varying the pressure with an aim of logical adjustment of the results with the asphaltene precipitation experimental data. The values established for the asphaltene solubility parameter in the first approach were somewhat underestimated compared to the reported values in the literature; however، the second approach gave more acceptable results. Finally، an empirical expression was proposed for asphaltene precipitation solubility estimation for the two oil samples with enhanced accuracy at different pressures.

Asphaltene deposition is an issue that has received much attention since it has been shown to be the cause of major production challenges. Asphaltene precipitation can occur during primary depletion of highly under-saturated reservoirs or during hydrocarbon gas or CO2 injection for improved oil recovery. Numerous laboratory researches and oilfield reports have investigated the effect of asphaltene deposition and its remediation under dynamic flow on reservoir rock properties. All techniques available into proper it، have proven costly and not highly effective، so prevention is the best way to counteract the problem. Revelation of the deposition mechanisms and determination of the parameters they influence it are essential in order to devise reliable prevention strategies. In this work، an experimental effort is made to investigate the permeability impairment of core samples، under natural depletion conditions and identify the dominant deposition mechanisms. The main tools that applied to do these experiments are permeability calculation، analysis of asphaltene concentration and high pressure and high temperature viscometer. Experiment carried on sandstone rock type. In addition، the study provides the deposition mechanism changes during production and it is strong dependent of oil injection rate.