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, which results in the deposition of paraffin in wells, decrease in oil production 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 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 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 flow rate causes the paraffin deposition zone to reduce, while increased gas content in oil leads to its increase. Based on 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.