An anomalous decline in production parameters has been observed since the beginning of the productive life of wells in the ultradeep Villafortuna-Trecate (VF-TR) field in northern Italy owing to the deposition of asphaltenes within the formation and tubing string.

This paper discusses the procedures that have been developed for monitoring well productivity performance based on the measured surface production parameters. These data are processed by means of well performance analysis in order to obtain a so-called Equivalent Productivity Index which is correlated with the Cumulative Production and has been used to determine when and if to carry out remedial solvent treatments, and to optimize the volumes and field treatment procedures.

Case histories of the most significant experiences are reported, including the results of production logs. These clearly show the progressive plugging of perforations owing to asphaltene deposition and the subsequent action of the solvent/acid treatments.

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