Patent ID: 8622139

Claim:
A wellhead-based control apparatus to control a well, the apparatus comprising: a wellhead housing configures to hang a plurality of casing strings, the wellhead housing including a bore adapted to receive the plurality of casing strings extending therethrough, each of the plurality of casing strings having a different diameter than each other of the plurality of casing strings; and an emergency well fluid shutoff assembly comprising: a casing strings compression assembly positioned to radially compress each of the plurality of casing strings, and a casing strings compression actuator operably coupled to the casing strings compression assembly to actuate the casing strings compression assembly. wherein a blowout preventer is connected to the wellhead housing: wherein substantial portions of the emergency well fluid shutoff assembly including the casing strings compression assembly are located below and separate from the blowout preventer; and wherein compression is performed at approximately a same coaxial location for each of the plurality of casing strings.