Buildup of waxy paraffin deposits in pipes has been studied for the example of the intrafield oil gathering system at the Songfangtun oil field. We have developed a predictive model for calculating the deposition rate in small-diameter gathering pipelines for water-cut oil. The model takes into account the effect of the water cut of the oil, its temperature and flow velocity on the impurity deposition rate. We have studied the mechanism for the effect of the indicated factors. The applicability of the model and the reliability of the results obtained were assessed from the average relative deviations between the predicted and measured values. The results of this work can be used to improve oil gathering systems and for cleaning the interior of pipelines (pigging).