Abstract: Drilling apparatus, such as an underreamer comprises a generally cylindrical tubular body and two cutting blades pivotally mounted to the body and movable between a retracted position and an extended position. Each cutting blade has a retracted position minimum gauge cutting portion and an extended position maximum gauge cutting portion, with the blades in the extended position the gauge cutting portions extending axially and being located in a transverse plane on or forward of the blade pivot axis.

Abstract: A downhole valve comprises a body defining a through bore and a valve member for location in the body and movable between an open position and a closed position. The valve has a first configuration in which the valve member is normally closed, and will hold a pressure differential in a first direction, and a second configuration in which the valve member is closed and will maintain a pressure differential in the first direction, and also in an opposite second direction and a third configuration in which the valve member is locked in the open position until it is deliberately closed.

Abstract: A downhole valve comprises a body defining a through bore and a valve member for location in the body and movable between an open position and a closed position. The valve has a first configuration in which the valve member is normally closed, and will hold a pressure differential in a first direction, and a second configuration in which the valve member is closed and will maintain a pressure differential in the first direction and also in an opposite second direction and a third configuration in which the valve member is locked in the open position until it is deliberately closed.

Abstract: Drilling apparatus, such as an underreamer comprises a generally cylindrical tubular body and two cutting blades pivotally mounted to the body and movable between a retracted position and an extended position. Each cutting blade has a retracted position minimum gauge cutting portion and an extended position maximum gauge cutting portion, with the blades in the extended position the gauge cutting portions extending axially and being located in a transverse plane on or forward of the blade pivot axis.

Abstract: Drilling apparatus, such as an underreamer (20) comprises a generally cylindrical tubular body (22) and two cutting blades (26, 27) pivotally mounted to the body and movable between a retracted position and an extended position. Each cutting blade has a retracted position minimum gauge cutting portion (36) and an extended position maximum gauge cutting portion (35), with the blades in the extended position the gauge cutting portions (35) extending axially and being located in a transverse plane on or forward of the blade pivot axis.

Abstract: A method of drilling and lining a bore in an earth formation comprises providing a tubular outer elongate member and an inner elongate member located within the outer member. At least one of the members is spoolable. A drill bit is mounted to one of the members and a bore is drilled by advancing the drill bit through the earth formation and advancing the members through the bore.

Abstract: The present invention generally relates to a method for recovering productivity of an existing well. First, an assembly is inserted into a wellbore, the assembly includes a tubular member for transporting drilling fluid downhole and an under-reamer disposed at the end of the tubular member. Upon insertion of the assembly, an annulus is created between the assembly and the wellbore. Next, the assembly is positioned near a zone of interest and drilling fluid is pumped down the tubular member. The drilling fluid is used to create an underbalanced condition where a hydrostatic pressure in the annulus is below a zone of interest pressure. The under-reamer is activated to enlarge the wellbore diameter and remove a layer of skin for a predetermined length. During the under-reaming operation, the hydrostatic pressure is maintained below the zone of interest pressure, thereby allowing wellbore fluid to migrate up the annulus and out of the wellbore.

Abstract: Drilling apparatus, such as an underreamer (20) comprises a generally cylindrical tubular body (22) and two cutting blades (26, 27) pivotally mounted to the body and movable between a retracted position and an extended position. Each cutting blade has a retracted position minimum gauge cutting portion (36) and an extended position maximum gauge cutting portion (35), with the blades in the extended position the gauge cutting portions (35) extending axially and being located in a transverse plane on or forward of the blade pivot axis.

Abstract: A method of drilling and lining a bore in an earth formation comprises providing a tubular outer elongate member and an inner elongate member located within the outer member. At least one of the members is spoolable. A drill bit is mounted to one of the members and a bore is drilled by advancing the drill bit through the earth formation and advancing the members through the bore.