FIELD: petroleum processing. SUBSTANCE: raw material and olefin-containing streams at paraffin to olefin volume ratio above 2 are fed into reactor with catalyst based on a solid acid, wherefrom upgraded target product is discharged. Olefin conversion level is at least 90 mol.%. Reactor is provided with internal circulation resulting in that dispersion value of residence time distribution for liquid in reactor exceeds 0.25 and, as a result, durability of catalyst constitutes at least 7 kg/kg. EFFECT: improved quality of product and increased catalyst lifetime. 15 cl, 1 tbl
