The pair got through their First Round match on England's south coast in straight sets, beating Fernando Romboli of Brazil and JP Smith of Australia 6-3, 6-3.
That set up their Quarter-final with Argentinian Comesana and Darderi of Italy, who survived seven break points across the first set to take it to a tiebreak.
Despite losing serve once, the number one seeded pair finally made their dominance count, breaking three times to take a 7-3 tiebreak win for a 7-6 victory in the first set.
Having broken their opponents' resistence, Heliovaara and Patten broke serve early in the second set, eventually taking a 3-0 advantage.
By defending their own serve, they did more than enough to earn themselves a spot in the Semi-finals, closing out a 7-6, 6-3 victory.
They will face Ariel Behar of Uruguay and Joran Vliegen of Belgium in the last four, which will be played tomorrow.
