produce heavier hydrocarbons by converting olefinic feedstock containing oxygenated hydrocarbons over an acidic zeolite catalyst the improvement comprises an extraction unit for removing oxygenates from the feedstock means for converting the extracted feedstock in a primary stage distillate mode catalytic reactor system under low severity conditions at high pressure and moderate pressure means for recovering the oxygenates and light hydrocarbons from the primary stage and a secondary stage reactor system for conversion of oxygenates under high severity conditions at substantially higher temperature than the primary stage thereby converting oxygenates and light hydrocarbons to heavier hydrocarbons application_number US 71631785 A description the oligomerization catalysts preferred for use herein include the crystalline aluminosilicate zeolites having a silica to alumina ratio of at least 12 a constraint index of about 1 to 12 and acid cracking activity of about 160 200 representative of the zsm 5 type zeolites are zsm 5 zsm 11 zsm 12 zsm 23 zsm 35 and zsm 38 zsm 5 is disclosed and claimed in u s pat no 3 702 886 and u s pat no re 29 948 zsm 11 is disclosed and claimed in u s pat no 3 709 979 also see u s pat no 3 832 449 for zsm 12 u s pat no 4.