Effect of Oil Saturation on Acid Propagation during Matrix Acidization of Carbonate Rocks

2014 ◽  
Author(s):  
R. Kumar ◽  
J. He ◽  
H. Nasr-El-Din
Keyword(s):  
Carbonate Rocks ◽  
Oil Saturation ◽  
Matrix Acidization

Effect of Oil Saturation on the Flow of Emulsified Acids in Carbonate Rocks

2014 ◽  
Vol 29 (01) ◽  
pp. 29-41 ◽  
Author(s):  
Mohammed A. Sayed ◽  
Ahmed I. Assem ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Carbonate Rocks ◽  
Oil Saturation

Recent Advances in Capillary Desaturation Curves for Sandstone and Carbonate Reservoirs

2021 ◽  
Author(s):  
Amaar Siyal ◽  
Khurshed Rahimov ◽  
Waleed AlAmeri ◽  
Emad W. Al-Shalabi
Keyword(s):  
Oil Recovery ◽  
Capillary Number ◽  
Carbonate Rocks ◽  
Carbonate Reservoirs ◽  
Residual Oil ◽  
Oil Saturation ◽  
Comparative Review ◽  
Remaining Oil ◽  
Capillary Desaturation ◽  
Wet Rocks

Abstract Different enhanced oil recovery (EOR) methods are usually applied to target remaining oil saturation in a reservoir after both conventional primary and secondary recovery stages. The remaining oil in the reservoir is classified into capillary trapped residual oil and unswept /bypassed oil. Mobilizing the residual oil in the reservoir is usually achieved through either decreasing the capillary forces and/or increasing the viscous or gravitational forces. The recovery of the microscopically trapped residual oil is mainly studied using capillary desaturation curve (CDC). Hence, a fundamental understanding of the CDC is needed for optimizing the design and application of different EOR methods in both sandstone and carbonate reservoirs. For sandstone reservoirs, especially water-water rocks, determining the residual oil saturation and generating CDC has been widely studied and documented in literature. On the other hand, very few studies have been conducted on carbonate rocks and less data is available. Therefore, this paper provides a comprehensive review of several important research studies published on CDC over the past few decades for both sandstone and carbonate reservoirs. We critically analyzed and discussed theses CDC studies based on capillary number, Bond number, and trapping number ranges. The effect of different factors on CDC were further investigated including interfacial tension, heterogeneity, permeability, and wettability. This comparative review shows that capillary desaturation curves in carbonates are shallower as opposed to these in sandstones. This is due to different factors such as the presence of high fracture density, presence of micropores, large pore size distribution, mixed-to-oil wetting nature, high permeability, and heterogeneity. In general, the critical capillary number reported in literature for sandstone rocks is in the range of 10−5 to 10−2. However, for carbonate rocks, that number ranges between 10−8 and 10−5. In addition, the wettability has been shown to have a major effect on the shape of CDC in both sandstone and carbonate rocks; different CDCs have been reported for water-wet, mixed-wet, and oil-wet rocks. The CDC shape is broader and the capillary number values are higher in oil-wet rocks compared to mixed-wet and water-wet rocks. This study provides a comprehensive and comparative analysis of CDC in both sandstone and carbonate rocks, which serves as a guide in understanding different CDCs and hence, better screening of different EOR methods for different types of reservoirs.

Study of the causes for wax deposition under the operating conditions of main oil pipelines

2020 ◽  
Vol 10 (6) ◽  
pp. 610-619
Author(s):  
Rustam Z. Sunagatullin ◽  
◽  
Rinat M. Karimov ◽  
Radmir R. Tashbulatov ◽  
Boris N. Mastobaev ◽  
...  
Keyword(s):  
Phase Diagrams ◽  
Total Content ◽  
Operating Conditions ◽  
Wax Deposition ◽  
Oil Saturation ◽  
Oil Pipelines ◽  
Thermobaric Conditions ◽  
Wall Zone ◽  
Significant Factors ◽  
Commercial Oil

The results of investigations of the main causes and the most significant factors of intensification of paraffin deposition in main oil pipelines are presented. A comprehensive analysis of the composition and properties of commercial oils and their sediments was carried out, according to which phase diagrams of equilibrium of oil dispersed systems were obtained using the example of commercial oils from Bashkir fields. Based on the phase diagrams, a curve of wax oil saturation was constructed, the analysis of which confirms that the existing thermobaric conditions during the operation of main oil pipelines do not allow transporting oil without the risk of waxing. It was noted a special influence of the value of the temperature gradient in the near-wall zone and the imbalance of the ratio of high-molecular oil components in commercial batches formed in the process of joint pumping on the intensity of waxing of sections of oil pipelines complicated by deposits, which was confirmed by statistical data on the frequency of pigging. The regularities obtained in this way are proposed to be used as an express method for predicting complications associated with intensive waxing of main oil pipelines. In order to quickly assess the risks of waxing of sections of main oil pipelines, an indicator is introduced that characterizes the ratio of the content of solid paraffins to the total content of resins and asphaltenes of oil, called the criterion of instability of a commercial oil batch.

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