Patent ID: 7237615

Claim:
A casing mandrel for wells completed using an independent screwed wellhead, comprising: a casing mandrel body having an annular shoulder adapted for mating engagement with a top flange of a casing bowl nut of the wellhead, an outer contour below the annular shoulder that mates with a casing bowl of the independent screwed wellhead, and an axial passage that extends from a casing mandrel bottom end to a casing mandrel top end of the casing mandrel body, the axial passage having a diameter at least as large as an internal diameter of a casing of a well to which the wellhead is mounted; and the casing mandrel top end extends above the annular shoulder, and includes a pin thread adapted for engagement with a box thread of a lockdown nut for securing a tubing head spool to the casing mandrel top end, the pin thread being located above a top of the casing bowl nut when the casing mandrel is secured to the independent screwed wellhead by the casing bowl nut.