storage device as can be seen from fig7 which is provided with an outer floating ring 15 which forms the structural basis responsible for supporting at least one flexible synthetic membrane 20 that is fastened to said ring 15 forming an upper membrane 20 a and a lower membrane 20 b with respect to this on the circumference of said floating ring 15 there is the arrangement of cables 100 that allow the whole structure to be towed and anchored as needed in said lower membrane 20 b at least one opening 30 is provided adjacent the outer floating ring 100 for engagement of a rising duct 30 u2032 u201c riser u201d which transports the oil into the device said rising duct u201c riser u201d can connect to any other oil collector device known in the art and through this connection the oil in its heavy form from an underground reservoir or a sunken ship can be transferred to the storage device still in the lower membrane 20 b is provided at least one duct to the water outlet 40 which allows only its output through a valve consisting of a buoy 70 with density smaller than water but greater than the oil from 0 99 to 0 81 preferably.