Inner bit disposed within an outer bit

US8550190B2 · kind B2 · utility

Inventors

• David R. Hall · Provo, US
• Francis Leany · Salem, US
• Casey Webb · Spanish Fork, US
• Marcus Skeem · Provo, US

Key dates

• Filing date: Sep 30, 2010
• Grant date: Oct 8, 2013
• Expiry date: Dec 8, 2031

Classification

• Technology area (CPC E): Fixed Constructions
• CPC primary: E21B10/62
• WIPO field: Civil engineering
• WIPO sector: Other fields

Abstract

In one aspect of the present invention, a drill bit assembly for downhole drilling comprises an outer bit comprising a central axis and an outer cutting area and an inner bit disposed within the outer bit and comprising an inner cutting area. The outer bit comprises a first plurality of cutting elements and the inner bit comprises a second plurality of cutting elements wherein an average distance of each cutting element in the first plurality to the central axis forms a first moment arm and an average distance of each cutting element in the second plurality to the central axis forms a second moment arm. A ratio of the inner cutting area to the outer cutting area is substantially equal to a ratio of the outer moment arm to the inner moment arm.