Tailoring hydrocarbon streams for asphaltene removal

Oilfield production is often hindered by asphaltene precipitation which tends to fill the pores of reservoir rocks and plug the wellbore tubing and other auxiliary equipment used during crude-oil recovery. Several remedies to remove these deposits have been proposed and patented, but the injection of aromatic solvents such as toluene and light petroleum distillates is normally preferred. Previous studies with a number of pure aromatic hydrocarbons have shown that the solvent capacity of these molecules may be very different and that the degree of condensation plays an important role. In this regard, tetralins and naphthalenes are superior to alkylbenzenes. However, because the use of pure compounds is not economically feasible, we examined various industrial streams and correlated their chemical composition to the solvent capacity. This work allowed the identification of the pseudocomponents whose relative concentration is crucial for evaluating the solvent performances. On the basis of these data, we were able to find new products with ideal characteristics. The efficiency of one of these products was confirmed by the analysis of the data obtained when using this new solvent to remove asphaltene in damaged wells of an Italian field.