Abstract: A subsea cap method and system having a canister attached to a port in a subsea cap that is positioned on a subsea structure and materials contained within the canister for release through the port into the defined area beneath the subsea cap and around the open upper end of the subsea structure. That is, the materials treat the water inside the cap and may optionally also treat the water outside the cap. The canister can be attached to, or removed from, the subsea cap subsea without removing the subsea cap from its resting place on the subsea structure. The system can be deployed via an ROV, diver or other means. The positioning of the subsea cap on the subsea structure and the placement and active or passive release of the material through the port into the defined area provides a system that protects the subsea structure from such problems as falling debris, silt, corrosion and organic growth while saving valuable time and resources.

Abstract: A ROV-deployable gas hydrate diverter comprising a body having a circular disc shape with a center hole, and a handle attached to and protruding from a surface of the body, wherein the handle is adapted to be grasped by the grasping arm of an ROV to facilitate installation of the gas hydrate diverter over a subsea wellhead.

Abstract: A cap for covering an open upper end of a subsea structure includes a base and a body. The base has a size, after shrinkage, at least slightly larger than the exterior of the open upper end of the subsea structure. The body is connected to the base and projects downward from the base. The body has an open bottom. The cap is positioned over the open upper end of the subsea structure with the base of the cap resting on the open upper end of the subsea structure and the body of the cap forms a wall around the exterior of the open upper end of the subsea structure for inhibiting the cap from slipping off the open upper end of the subsea structure.