Patent ID: 7431079

Claim:
A well blowout prevention apparatus comprising: an elongated tubular housing adapted to insertion inside a well casing, the elongated tubular housing comprising: an upper housing member and a lower housing member, wherein, (i) one of the upper housing member and the lower housing member has male threads, and the other of the upper housing member and the lower housing member has female threads, and (ii) the upper housing member connects to the lower housing member by engagement of the male threads with the female threads; and an anchoring mechanism, wherein: rotating the upper housing member in a first direction relative to the lower housing member screws the upper and lower housing members together and exerts anchoring force on the anchoring mechanism, the anchoring force being adapted to cause the anchoring mechanism to engage an inner well casing wall, where the elongated tubular housing is located inside the well casing; and the anchoring mechanism is adapted to (i) secure the elongated tubular housing inside the well casing, and, (ii) substantially disengage from the inner well casing wall when the anchoring force on the anchoring mechanism is substantially relieved by rotating the upper housing member in a second direction relative to the lower housing member; and a valve assembly, the valve assembly being, (i) disposed inside the elongated tubular housing, and, (ii) adapted to substantially prohibit fluid flow that exceeds a threshold rate from flowing up through the elongated tubular housing.