Simulation of paraffin deposition in reservoirs

Paraffin deposition within the reservoir can cause a significant decrease in reservoir performance. Although it is not a well documented problem, it is of major concern in some reservoirs. The purpose of this research was (1) to develop a numerical simulator to model the depositional and removal processes of paraffin in the reservoir, and (2) to gain a better understanding as to how these processes affect reservoir performance. This is believed to be the first such simulator.;A two-dimensional, three-component simulator was developed to model the paraffin depositional and removal processes. The mechanisms which were modeled include (1) effects of dissolved gas and temperature on paraffin solubility/precipitation, (2) deposition of precipitated paraffin, and (3) reduction in permeability caused by paraffin deposition. Each mechanism was studied and modeled independently, after which they were incorporated into a reservoir simulator. The simulator was validated by matching both analytical solutions and existing laboratory results. Then cases were run to simulate field conditions.;The results indicate that suspended paraffin particles do not travel far. However, significant skin damage can occur because of solid paraffin buildup near the wellbore. This buildup yields a rapid reduction in production rates. Skin damage continues to increase if gas evolution causes precipitation near the wellbore.;Results show that electrical resistance heating (ERH) removes the skin damage very rapidly. This suggests that ERH could be used intermittently to effectively remove paraffin buildup whenever production rates indicate an increase in skin damage.