Laboratory testing and simulation of the paraffin deposition in Turija field oil well in Vojvodina region, Serbia

Abstract

In Serbia approx. 70% of the crude oil produced accounts for the heavy oil type, these results in the deposition of paraffin in wells, oil production decrease while increasing the operating costs. Different methods, such as mechanical, chemical and thermal, are applied in effort to solve the paraffin deposition problem. Most methods require an accurate determination of that the deposition zone in well. In this paper, experimental and simulation results of the parameter analysis affecting intensity and zone of paraffin deposition in oil wells are presented. The analysis has been done for heavy oil produced from the oil field Turija, Vojvodina region, Serbia. The paraffin deposition curves and paraffin deposition intensity during time are experimentally defined. The influence of temperature gradient, fluid flow rate and gas content in oil changes on the paraffin deposition zone change was analyzed by the computer simulation. It was found that temperature gradient changes can cause paraffin deposition zone to change approx. 22 m, i.e. maximum 43 m. It was also determined that the length of paraffin deposition zone can change up to 140 m due to the changes in the fluid flow rate or in the gas content in oil. The increase of the flow rate causes paraffin deposition zone to reduce, while increased gas content in oil leads to its increase. On the basis of the obtained results, the optimal working parameters of mechanical method, such as frequency and depth of paraffin scraping as well as temperature and heating cable power of thermal methods can be determined.