Patent ID: 8225888
Filing Date: 2012-07-24
Classification: E21B

Abstract:
1. A casing shoe configured for attachment to at least one section of casing and for drilling or reaming a wellbore as the at least one section of casing is advanced into contact with subterranean formation material, the casing shoe comprising: a nose portion having an inner profile and an outer profile; a gage portion extending longitudinally from the nose portion; a plurality of blades; and a first plurality of cutting elements fixedly mounted on the casing shoe in a first region of the casing shoe to be subsequently drilled through by another drilling tool, the first region extending radially from the longitudinal axis of the casing shoe to a first radial position, each cutting element of the first plurality of cutting elements comprising a volume of abrasive material; a second plurality of cutting elements mounted on the casing shoe in a second region of the casing shoe not to be subsequently drilled through by another drilling tool, the second region extending radially outward from the first radial position to a second radial position, the second plurality of cutting elements having a material composition differing from the first plurality of cutting elements, the first plurality of cutting elements being more susceptible to wear relative to the second plurality of cutting elements.