The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 13, 2012
Filed:
Jun. 05, 2008
Alan Martyn Eddison, Aberdeen, GB;
Alan Martyn Eddison, Aberdeen, GB;
National Oilwell Varco, L.P., Houston, TX (US);
Abstract
Drilling apparatus comprises: a body; a pilot hole-drilling assembly () mounted to the body for drilling a pilot hole of a first diameter; and a hole-opening assembly () mounted to the body for opening the pilot hole to a larger second diameter. The apparatus is configured such that the pilot hole-drilling assembly () will drill at a faster rate than the hole-opening assembly () for a given unit loading. As the pilot hole-drilling assembly () has the capability to drill at a faster rate than the hole-opening assembly (), the pilot hole-drilling assembly will tend to experience relatively low weight-on-bit (WOB). The pilot hole-drilling assembly () will thus tend to maintain a vertical orientation. The hole-opening assembly () will follow the path of the pilot hole, while opening the hole to the required diameter.