The Comparison of Effects of Immiscible Injection of Natural/Nitrogen Gases on Asphaltene Precipitation Process

Asphaltene and wax deposition in the course of production of many Iranian reservoirs has become a serious problem. In order to investigate the effect of injecting rich and dry natural gases and also nitrogen, on the asphaltene precipitation process a comprehensive research study was launched. Three phase equilibrium calculation of NGHIEM and his co-workers is used. In the method pure asphaltene in the oil is considered as solid and the heavy part of the oil is split as precipitating and non- precipitating. The provided model is able to describe the phase behavior of reservoir oil encountered with a compositional disturbance caused by injecting light fluids into the reservoir during the production period. In this work, first, the natural depletion model of each case is constructed and then the changes of behavior by injecting rich and dry natural gases and also high nitrogen content gas is investigated. Also the change in onset of asphaltene precipitation for different injections is shown. The achieved results show that the nitrogen gas has more moderate effect on precipitation process compared to more vigorous effect of dry and rich gases.