Methods for loading a compressed fluid, such as natural gas, into and discharging the compressed fluid out of containment are provided. The compressed fluid is injected into a bottom portion of a container system for storage and/or transport until a target pressure is reached after which gas is withdrawn from an upper portion of the container system at a rate to maintain the target pressure while the compressed fluid is injected in the bottom portion. The compressed fluid is cooled through an expansion valve and by refrigerated chillers or by injecting a cold liquid of the same chemical composition as the compressed fluid, such as liquid natural gas, into the compressed fluid prior to injection into the container system. Withdrawal or discharge from the container system to a receiving facility begins with blow down from the bottom portion of the container system without a displacement fluid and continues until pressure falls below an acceptable differential pressure. The discharge stream is passed through a separator and a light gas from the separator is pressurized and injected into an upper portion of the container system to drive the compressed fluid out the bottom. The light gas is pressurized using either a compressor or a heated tank system, where two vessels operate in parallel, trapping and heating the light gas and then discharging to the container system from one while filling the other and alternating the operation between the two.