Pressure equalization for well pressure control device

A method for use with a subterranean well, the method comprising:

• positioning a tubular string in a riser string, the riser string including an outer housing of a pressure control device and a first annular seal operable to prevent flow through an annulus formed between the tubular string and the riser string, the tubular string including an equalization valve and a running tool operable to convey a releasable assembly of the pressure control device through the riser string, the releasable assembly being releasably securable in the outer housing;
• and
• opening the equalization valve, thereby permitting fluid communication between the annulus and a flow passage extending longitudinally through the tubular string, in which the permitting fluid communication comprises flowing a fluid in a downward direction through the flow passage at greater than a predetermined flow rate.

A system for use with a subterranean well, the system comprising:

• a riser string including an annular blowout preventer, the annular blowout preventer including a first annular seal displaceable into sealing contact with an exterior surface of a tubular string to thereby prevent flow through an annulus between the riser string and the tubular string;
• and
• the tubular string including a running tool and an equalization valve, the running tool being releasably attachable to a releasable assembly, the releasable assembly being releasably securable in the riser string, the releasable assembly including a second annular seal that sealingly and slidingly contacts the exterior surface of the tubular string, and the equalization valve selectively preventing and permitting fluid communication between a flow passage extending longitudinally through the tubular string and a first section of the annulus positioned between the first and second annular seals, in which the equalization valve operates between open and closed configurations in response to variations in fluid flow rate of a downward fluid flow through the flow passage.