p =ρGH = 1.03× 103kg/m3× 10N/kg× 1500m = 1.545× 107 pa，
Sea water pressure on 1m2 area:
f = pS = 1.545× 107 pa× 1 m2 = 1.545× 107n；
(2) Oil quantity in the South China Sea:
v = mρ= 3.645× 10 13kg 0.8 1× 103kg/m3 = 4.5× 10 10 m3。
Answer: (1) At seawater depth 1500m, the pressure of water on the bit is1.545×107 Pa; At such a deep seabed, the seawater pressure on the area of 1m2 is1.545×107n;
(2) The oil quantity in the South China Sea is at least 4.5×1065438+100m3.