Patent ID: 8042613
Filing Date: 2011-10-25
Classification: E21B,Y10T

Abstract:
1. A downhole drilling head, comprising: a hole saw having a cylindrical body with a circumferential rim and a longitudinal axis going through a centre of the cylindrical body, and a drill bit extending along the longitudinal axis and through the centre of the cylindrical body, wherein the circumferential rim has at least one cutting edge inclining at least partly towards the longitudinal axis of the cylindrical body, and wherein the cutting edge is rotatable and capable of cutting a piece out of at least one of a stuck metal valve or a formation downhole, and wherein the cutting edge inclines at least partly towards the longitudinal axis of the cylindrical body so that an inner diameter (D) of the body decreases at least 2% forming a tip diameter (d) at a tip of the cutting edge.