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Improve the Rheological Behavior of Different Waxy Crude Oil by Using Variouse Additives

Rezaei, Shirzad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53471 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghotbi, Cyrus; Jafari Behbahani, Taraneh; Ramezani Saadatabadi, Ahmad
  7. Abstract:
  8. Wax precipitation is one of the major problems in the transfer of crude oil from field production to refineries. This wax with asphaltene compounds and some water and solids, closes the oil pipeline. One of the ways to reduce the amount of wax in pipes is to use additives (flow improvers) to crude oil and improve its rheological behavior. In this research, Five Iranian crude oils were characterized with SARA test and then the effects of various additives including ethylene vinyl acetate (EVA) in concentrations of 500 and 1500 ppm, alkyl phenol ormaldehyde resins (NPFR) with 1500 ppm and styrene-(ethylene-cobutylene)- styrene (SEBS) with 1500 ppm on viscosity, wax appearance temperature (WAT) and pour point were evaluated. The rheological behavior of these crude oils in the absence/presence in flow improvers was studied and WAT was determined with rheometry and cross polarized microscopy. To evaluate of flow behavior with use additives, experimental data were fitted with the thermodynamic equation for each crude oil and the best equation was determined. The results of all additives on the rheological properties of crude oil (4) were studied and in other oils, only the impact of the SEBS was evaluated. Finally, the rheological behavior of Maleko Sarkon crude oil was simulated with the PVTsim and OLGA software and the amount of wax precipitation was investigated in pipeline. The results showed that improver materials reduced the viscosity of crude oil and flow behavior was approached to linear trend at high temperature. In the use of additives, WAT was reduced which this decrease was different in types of crude oil with various characteristics. Comparing the effect of various additives on the improvement of rheological behavior of crude oil (4) showed that effect of EVA 1500 was the highest and NPFR 1500 was the least. In general, the positive effect of the additives was as follows: EVA1500 > SEBS1500 > EVA500 > NPFR1500. The results of the thermodynamic equations fitting showed that by decreasing the temperature and forming the wax crystals, the flow behavior is exited from the Newtonian fluid, and non-Newtonian equations describing the flow behavior of crude oils. In the simulation of Maleko-Sarkon crude oil, an acceptable adaptation between experimental and simulation data was showed. Formation of wax precipitation simulation in length of the old and new pipes showed that in a new pipe, with a longer length, the amount of wax precipitation and the pressure drop was lower than the old pipe
  9. Keywords:
  10. Wax Percipitation ; Additives ; Rheology ; OLGA Software ; Rheological Properties ; Cross Polarized Microscope (CPM) ; Ethylene Vinyl Acetate (EVA)

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