Patent ID: 8146683

Claim:
A drilling assembly for drilling two or more casing sections into a subterranean formation comprising: a first casing bit and a second, smaller casing bit, each casing bit of different diameter affixed to a respective casing section of different diameter, at least two casing bits and the two or more casing sections arranged in a telescoping relationship; the second casing bit configured to drill out the first casing bit and comprising: a bit body having a face at a leading end thereof; a first plurality of cutting elements of at least one type disposed over the bit body, the cutting elements of the at least one type each exhibiting an exposure; and a second plurality of cutting elements of at least another, different type disposed over the bit body, each cutting element of the at least another, different type exhibiting an exposure relatively greater than an exposure of a proximate cutting element of the at least one type.