Do Asphaltene Deposition Troubles Happen In Low Asphaltene Content Of Crude Oil?

2012 ◽  
Author(s):  
Katsumo Takabayashi ◽  
Haruo Maeda ◽  
Yoshihiro Miyagawa ◽  
Masayuki Ikarashi ◽  
Hiroshi Okabe ◽  
...  
Keyword(s):  
Crude Oil ◽  
Asphaltene Content ◽  
Asphaltene Deposition

Review of the Molecular Structure and Aggregation of Asphaltenes and Petroleomics

SPE Journal ◽  
2008 ◽  
Vol 13 (01) ◽  
pp. 48-57 ◽  
Author(s):  
Oliver C. Mullins
Keyword(s):  
Pressure Drop ◽  
Crude Oil ◽  
Common Knowledge ◽  
Oil Refining ◽  
Crude Oils ◽  
Strong Temperature Dependence ◽  
Specific Chemical ◽  
Asphaltene Content ◽  
Asphaltene Deposition ◽  
Asphaltic Materials

Summary Tremendous strides have been made recently in asphaltene science. Many advanced analytical techniques have been applied recently to asphaltenes, elucidating many asphaltene properties. The inability of certain techniques to provide correct asphaltene parameters has also been clarified. Longstanding controversies have been resolved. For example, molecular structural issues of asphaltenes have been resolved; in particular, asphaltene molecular weight is now known. The primary aggregation threshold has recently been established by a variety of techniques. Characterization of asphaltene interfacial activity has advanced considerably. The hierarchy of asphaltene aggregation has emerged into a fairly comprehensive picture, essentially in accord with the Yen model with the additional inclusion of certain constraints. Crude oil and asphaltene science is now poised to develop proper structure-function relations that are the defining objective of the new field: petroleomics. The purpose of this paper is to review these developments in order to present a more clear and accessible picture of asphaltenes, especially considering that the asphaltene literature is a bit opaque. Introduction The asphaltenes are a very important class of compounds in crude oils (Chilingarian and Yen 1978; Bunger and Li 1981; Sheu and Mullins 1995; Mullins and Sheu 1998; Mullins et al. 2007c). The asphaltenes represent a complex mixture of compounds and are defined by their solubility characteristics, not by a specific chemical classification. A common (laboratory) definition of asphaltenes is that they are toluene soluble, n-heptane insoluble. Other light alkanes are sometimes used to isolate asphaltenes. This solubility classification is very useful for crude oils because it captures the most aromatic portion of crude oil. As we will see, this solubility defintion also captures those molecular components of asphaltene that aggregate. Other carbonaceous materials such as coal do possess an asphaltene fraction, but that often will not correspond to the most aromatic fraction. Petroleum asphaltenes, the subject of this paper, can undergo phase transitions that are an impediment in the production of crude oil. Fig. 1 shows a picture of an asphaltene deposit in a pipeline; obviously, asphaltene deposition is detrimental to the production of oil. Immediately it becomes evident that different operational definitions apply for the term asphaltene in the field vs. the lab. Indeed, the field deposit is very enriched in n-heptane-insoluble, toluene-soluble materials, but this field asphaltene deposit is not identically the standard laboratory solubility class. It is common knowledge that a pressure drop on certain live crude oils (containing dissolved gas) can cause asphaltene flocculation, the first step in creating deposits that are seen in Fig. 1. Highly compressible, very undersaturated crude oils are most susceptible to asphaltene deposition problems with a pressure drop (de Boer et al. 1995). In depressurization flocculation, the character of the asphaltene flocs is dependent on the extent of pressure drop, suggesting some variations in the corresponding chemical composition (Hammami et al. 2000; Joshi et al. 2001). Comingling different oils can result in asphaltene precipitation that can resemble solvent precipitation. Asphaltenes are hydrogen-deficient compared to alkanes; thus, either hydrogen must be added or coke removed in crude oil refining to generate transportation fuels. Thus, asphaltene content lowers the economic value of crude oil. Increasing asphaltene content is associated with dramatically increasing viscosity, especially at room temperature; again, this is of operational concern. The strong temperature dependence of viscosity of asphaltic materials is one of their important properties that make them useful for paving and coating; application of asphaltic materials is facile at moderately high temperatures, while desired rheological properties are obtained at ambient temperatures.

scholarly journals Impact of Asphaltene Presence in Heavy Crude Oil and Its Separation Technique

2019 ◽  
Vol 9 (2) ◽  
pp. 1278-1281
Keyword(s):  
Crude Oil ◽  
Separation Technique ◽  
Heavy Crude Oil ◽  
Gas Composition ◽  
Research Article ◽  
Oil Transportation ◽  
Asphaltene Content ◽  
Asphaltene Deposition ◽  
Heavy Crude

Heavy crude oil is the crude oil with no gas composition and major constituents are asphaltene, resins, saturates and aromatics. Heavy crude oil is capable of producing a low high valued products and high low valued products. Asphaltene is a molecular substance that acts as a binding molecule to help in the recovery of heavy crude oil. On the contrary, an asphaltene deposition becomes troublesome in the heavy crude oil transportation through pipelines. In this research article, the heavy crude oil was collected from the western part of Indian oilfield and subjected to the separation of asphaltene content by the addition of aliphatic solvent. The results of separation of asphaltene from the heavy crude oil by the addition of n-heptane and n-hexane were found to be 15 wt. % and 17 wt. %. The asphaltene will cause moderate deposition problem during the production and transportation of investigated heavy crude oil.

Experimental Investigation of Asphaltene-Induced Formation Damage Caused by Pressure Depletion of Live Reservoir Fluids in Porous Media

SPE Journal ◽  
2018 ◽  
Vol 24 (01) ◽  
pp. 01-20 ◽  
Author(s):  
Omid Mohammadzadeh ◽  
Shawn David Taylor ◽  
Dmitry Eskin ◽  
John Ratulowski
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Flow Rate ◽  
Formation Damage ◽  
Bulk Fluid ◽  
Asphaltene Content ◽  
Pressure Depletion ◽  
Asphaltene Deposition ◽  
Permeability Impairment ◽  
Live Oil

Summary One of the complex processes of permeability impairment in porous media, especially in the near-wellbore region, is asphaltene-induced formation damage. During production, asphaltene particles precipitate out of the bulk fluid phase because of pressure drop, which might result in permeability reduction caused by both deposition of asphaltene nanoparticles on porous-medium surfaces and clogging of pore throats by larger asphaltene agglomerates. Experimental data will be used to identify the parameters of an impairment model being developed. As part of a larger effort to identify key mechanisms of asphaltene deposition in porous media and develop a model for asphaltene impairment by pressure depletion, this paper focuses on a systematic design and execution of an experimental study of asphaltene-related permeability damage caused by live-oil depressurization along the length of a flow system. An experiment was performed using a custom-designed 60-ft slimtube-coil assembly packed with silica sands to a permeability of 55 md. The customized design included a number of pressure gauges at regular intervals along the coil length, which enabled real-time measurement of the fluid-pressure profile across the full length of the slimtube coil. The test was performed on a well-characterized recombined live oil from the Gulf of Mexico (GOM) that is a known problematic asphaltenic oil. Under a constant differential pressure, the injection flow rate of the live oil through the slimtube coil decreased over time as the porous medium became impaired. During the impairment stage, samples of the produced oil were collected on a regular basis for asphaltene-content measurement. After more than 1 month, the impairment test was terminated; the live oil was purged from the slimtube coil with helium at a pressure above the asphaltene-onset pressure (AOP); and the entire system was gently depressurized to bring the coil to atmospheric conditions while preserving the asphaltene-damaged zones of the coil. The permeability and porosity of the porous medium changed because of asphaltene impairment that was triggered by pressure depletion. Results indicated that the coil permeability was impaired by approximately 32% because of pressure depletion below the AOP, with most of the damage occurring in the latter section of the tube, which operated entirely below the AOP. Post-analytical studies indicated lower asphaltene content of the produced-oil samples compared with the injecting fluid. The distribution of asphaltene deposits along the length of the coil was determined by cutting the slimtube coil into 2- to 3-ft-long sections and using solvent extraction to collect the asphaltenes in each section. The extraction results confirmed that the observed permeability impairment was indeed caused by asphaltene deposition in the middle and latter sections of the coil, where the pressure was less than the AOP. With the success of this experiment, the same detailed analysis can be extended to a series of experiments to determine the effects of different key parameters on pressure-induced asphaltene impairment, including flow rate, wettability, and permeability.

Asphaltene Deposition Induced by Carbon Oxide and its Influence on Displacement Efficiency

2012 ◽  
Vol 594-597 ◽  
pp. 2451-2454
Author(s):  
Feng Lan Zhao ◽  
Ji Rui Hou ◽  
Shi Jun Huang
Keyword(s):  
Crude Oil ◽  
Oil Recovery ◽  
Carbon Oxide ◽  
Viscosity Reduction ◽  
Core Flooding ◽  
Displacement Efficiency ◽  
Oil Composition ◽  
Oil Viscosity ◽  
Asphaltene Deposition ◽  
Total Oil

CO2is inclined to dissolve in crude oil in the reservoir condition and accordingly bring the changes in the crude oil composition, which will induce asphaltene deposition and following formation damage. In this paper, core flooding device is applied to study the effect of asphaltene deposition on flooding efficiency. From the flooding results, dissolution of CO2into oil leads to recovery increase because of crude oil viscosity reduction. But precipitated asphaltene particles may plug the pores and throats, which will make the flooding effects worse. Under the same experimental condition and with equivalent crude oil viscosity, the recovery of oil with higher proportion of precipitated asphaltene was relatively lower during the CO2flooding, so the asphltene precipitation would affect CO2displacement efficiSubscript textency and total oil recovery to some extent. Combination of static diffusion and dynamic oil flooding would provide basic parameters for further study of the CO2flooding mechanism and theoretical evidence for design of CO2flooding programs and forecasting of asphaltene deposition.

Effects of Asphaltene Content and Temperature on Viscosity of Iranian Heavy Crude Oil: Experimental and Modeling Study

2013 ◽  
Vol 27 (12) ◽  
pp. 7217-7232 ◽  
Author(s):  
Mahdi Ghanavati ◽  
Mohammad-Javad Shojaei ◽  
Ahmad Ramazani S. A.
Keyword(s):  
Crude Oil ◽  
Heavy Crude Oil ◽  
Asphaltene Content ◽  
Heavy Crude ◽  
Modeling Study
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