For my opinion this wreck rather looks like project 1265 minesweeper then project 699. May be she was BT-15 with yard number 136. BT-15 was decommissioned in 2002 with pennant number 478.

Looks like the remnants of a Vanya (NATO) project 699,257D/DM minesweeper. These had wooden hulls and I think you can see, just, the planking. Some more portholes then I can find on photos but the hull is the right size and shape.
Regards /Göran