A Novel Method for Mitigation of Asphaltene Deposition in the Wellstring

Asphaltene precipitation and deposition is a serious problem in many Iranian fields. The deposited asphaltene results in partial or total blockage of the wellbore and wellstring reducing or completely seizing oil production. This paper studies the asphaltene problem and mitigation methods in wellstring systematically. It presents new approach based on the combination of thermodynamic modeling of asphaltene precipitation with hydrodynamic well modeling. The developed model is capable to determine the asphaltene precipitation and deposition interval through the wellstring. Therefore, it could study the effect of hydrodynamic parameters such as wellhead pressure, well flow-rate and tubing size on the mitigation of asphaltene deposition. The conventional way to treat asphaltene deposition was through remediation which attacks the problem after it occurs. This model is capable to determine the severity of asphaltene deposition even before start of production. The model was applied to simulate the asphaltene precipitation in one of the south Iranian oil fields (Kupal) and important guidelines have been studied to mitigate the risks associated with asphaltene deposition. The results of modeling show that change in hydrodynamic condition could reduce and mitigate asphaltene deposition damage. But in some cases it would not be possible to prevent asphaltene precipitation completely. Therefore, the approach for flow assurance in those cases would be to change the well completion and inject asphaltene inhibitor, in order to prevent deposition of asphaltene flocculates.