With reference to the BP oil spill, this containment cap can be made quickly from readily available materials, and be used to temporarily (until relief wells can be completed) stop the flow of oil and gas from the well head. The bottom of the cap will either rest on bedrock or extend to a sufficient depth in the sediment to provide backpressure against the well pressure and prevent blowout through the bottom. It will also prevent well casing blow out and contain leakage from any well casing fracture that might exist. The cap is sufficiently heavy to bury itself. Anchor cables can be used to stabilize the cap. The valve mounted on top of the cap will be used to vent or "burp" during installation and can be used for siphoning if desired. Injection ports are available for dispersant or hot water from ships if necessary. The existing BOP tower can either be removed or left in place and be encased by the cap. The point is to STOP THE FLOW until a permanent solution can be arranged.