STUDY OF THE EFFECTIVENESS OF SOLVENTS FOR REMOVING ASPHALTENE-RESIN-PARAFFIN DEPOSITS

Abstract

The accumulation of asphaltene, resin and paraffin deposits in the near-wellbore formation zone, as well as in downhole and surface production equipment, poses a significant operational challenge in oil field development. This article focuses on scientifically justifying and selecting effective formulations comprising hydrocarbon solvents and modifying additives designed to remove and inhibit these deposits. It uses wells from Field A as a case study. The effectiveness of the formulations was evaluated using the 'cold cylinder' method and by determining the pour-point depression effect (ΔTpour) at 20°C and 50°C. To dissolve deposits in wells No. 141, 148, 58, 188, 35 and 201, the study tested treated crude oil, stable gas condensate and bottoms residue (light oil from the Dolyna Gas Processing Plant), as well as binary mixtures of these containing 10% depropanizer bottoms, propanil, xylene and acetic acid. The study determined that treated crude oil exhibits the highest initial solubility at 20 °C (up to 70.7%). Increasing the temperature to 50 °C speeds up the breakdown of the paraffin phase and increases the dissolving capacity of the tested systems by 15–35%. The use of modifiers was found to have a synergistic effect, ensuring the dissolution of asphaltene-resin-paraffin deposits at a rate of 80–88%. Furthermore, distinct zonal heterogeneity in deposit composition relative to depth has been demonstrated (as evidenced by Well No. 188: 0–300 m, 300–600 m, 600–900 m and 370–420 m in Well No. 201), confirming the need for a differentiated approach to reagent selection. Based on the test results, specific technological recommendations have been formulated for each well, covering the choice of solvent type, additives, temperature conditions and treatment duration. These recommendations provide a basis for optimising treatment protocols for the near-wellbore formation zone and downhole equipment.