The NFL has awarded 33 compensatory picks to 13 clubs. Seattle gets three, a 3rd rounder (97th overall), a 5th rounder (171), and a 6th rounder (215). This is the expected amount of picks that Seattle would receive, and the round numbers are exactly what was predicted by Over The Cap. The comp picks this year are not tradable, but that rule will change in 2017 and compensatory picks will be tradable.
With Seattle's three additional picks, they now have nine total, including four in the top 100 picks. That's a big deal.
Seattle made trades to acquire safety Kelcie McCray (using their 2016 5th rounder) and cornerback Mohammed Seisay (using their 2016 6th rounder). However, they did pick up an additional 7th round pick from Dallas for the Christine Michael trade.
The comp picks were rewarded because of Seattle's losses in free agency: a 3rd rounder for Byron Maxwell, a 5th rounder for James Carpenter, and a 6th rounder for Malcolm Smith. Seattle would've gotten another comp pick for losing Jeron Johnson to Washington, but the signing of Ahtyba Rubin cancelled that out.
Overall, here's where that leaves Seattle:
Round 1: 26th overall
Round 2: 56th overall
Round 3: 90th overall
Round 3: 97th overall (compensatory pick for Byron Maxwell)
Round 4: 124th overall
Round 5: 171st overall (compensatory pick for James Carpenter)
Round 6: 215th overall (compensatory pick for Malcolm Smith)
Round 7: 225th overall (acquired from Dallas for Christine Michael)
Round 7: 247th overall