Patent ID: 6695059
Filing Date: 2004-02-24
Classification: E21B

Abstract:
In a subsea well assembly having an outer wellhead housing adapted to be located at a sea floor, an inner wellhead housing which lands in the outer wellhead housing, the inner wellhead housing having an upper end that protrudes above the outer wellhead housing, the inner wellhead housing having a grooved profile extending circumferentially around an exterior portion of the upper end for connection to a riser leading upward to a surface vessel, an improved anti-rotation device for preventing rotation of the inner wellhead housing in the outer wellhead housing comprising in combination:at least one slot formed in a sidewall of one of the wellhead housings; and at least one key secured to a sidewall of the other of the wellhead housings, the key being received in the slot when the inner wellhead housing lands in the outer wellhead housing at the sea floor.