Impact of production operating conditions on asphaltene induced reservoir damage: A simulation study

Abstract

Asphaltene deposition in the near well bore region, tubing and surface facilities causes chronic problems in oil industry. Mechanical, thermal and chemical approaches are frequently being used but each suffers from certain limitations and shortcomings. The utilization of such methods also comes usually with a large price tag as these require mechanical equipment, pumps, new completion and tubing, solvents and chemical materials. Needless to say that these are often performed during well shutdown. The choice of optimal production operating conditions which otherwise would prevent or diminish asphaltene deposition is preferential. In previous studies, producing with low bottom hole pressure (BHP) has been proposed as a viable solution for some of asphaltenic oil fields, but a thorough and detailed study is still lacking. In this study, a comprehensive simulation methodology is developed to tackle impacts of BHP conditions on the asphaltene deposition. An IMPES (Implicit Pressure and Explicit Compositions) cylindrical, compositional simulator is developed which considers asphaltene deposition dynamically. Precipitated asphaltene is considered as a pure dense liquid which is determined by LLE calculation using PR-EoS. The amount of deposition is obtained through three mechanisms of surface deposition, entrainment and pore throat plugging. The permeability reduction is correlated with porosity reduction using a power-law relation. Detailed analysis of the simulated cases reveals that selecting a very low BHP (bellow bubble point pressure) would maintain the reservoir in a desirable pressure range far from the maximum deposition point.