Environmental protection for subsea wells

Abstract

An enclosed protective chamber for a subsea wellhead assembly includes a main body installed on the sea floor. Subsea wellhead apparatus is mounted in the chamber on top of a well. A pressure-containing lid is mounted on and sealed with respect to the main body such that chamber pressure is isolated from the subsea hydrostatic head. An inflatable, elongated, flexible storage tank or dracon is attached to the chamber through a conduit having a pressure-balanced relief valve therewithin. The dracon is attached to the conduit through a quick disconnect coupling and closure valve which permit ready attachment, removal, or replacement of the dracon. Under normal operating conditions the dracon is deflated. The dracon is preferably anchored to the sea floor. When a leak in the subsea wellhead assembly occurs, excess chamber pressure permits surplus fluid to enter and fill the dracon. The dracon may then be disconnected from the conduit, the anchor released, and the dracon removed to the surface for retrieval or disposal of the fluid contents. Substantially no well or chamber fluids ar released into the sea during the dracon removal and reinstallation processes. A pop-off cap and expandable conduit may be mounted on top of the chamber.