A passive annular grout seal assembly is disclosed for sealing an annular opening between a driven pile and a skirt pile sleeve for an offshore platform. The annular seals are located at the bottom of the pile sleeves near sea floor and automatically activated when piles are inserted and driven through the pile sleeves without any active operational procedure during offshore piling. The seal configuration fully utilizes the seal height, the grout column height and the density difference between grout and sea water to produce enhanced sealing capacity against the column of grout above.