| 摘要 |
A drilling assembly for drilling two or more casing sections into a subterranean formation includes a first casing bit and a second 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 includes a bit body having a face on which two different types of cutting elements are disposed, the first type being cutting elements for drilling at least one subterranean formation and the second type being cutting elements for drilling through the first casing bit. |
