Patent attributes
A centralizer assembly for centralizing casing inside a riser includes a locking element to move generally radially outward from the casing toward the riser in response to a change in pressure in the annulus between the casing and the riser. The locking element may be a first wedge shaped element adapted for movement in a radial direction from the casing toward the riser and a second wedge shaped element adapted to move generally axially along the casing and adapted for engaging the first wedge shaped element in response to a pressure activated driver. The driver may be a rupture device that ruptures when the pressure in the annulus reaches a predetermined threshold. Ratchet teeth are included between the elements for engaging and locking the wedge shaped elements in position once driven by the driver.
