A nested drill bit assembly is disclosed for drilling a wellbore, comprising a parent bit and at least one child bit nested within the parent bit. Each bit in the nested drill bit assembly may be driven by a respective casing that gets cemented in place as part of a drilling with casing system. The parent bit and child bit(s) may be rotated together, with the parent bit and child bit collectively defining a contiguous cutting profile for drilling an initial segment of the wellbore. A driver is then lowered into the casing for connection to the child bit to drill beyond the parent bit. The driver may be configured as a drive bit for drilling through material leftover from a cementing operation prior to connecting to the child bit.

A nested drill bit assembly is disclosed for drilling a wellbore, comprising a parent bit and at least one child bit nested within the parent bit. Each bit in the nested drill bit assembly may be driven by a respective casing that gets cemented in place as part of a drilling with casing system. The parent bit and child bit(s) may be rotated together, with the parent bit and child bit collectively defining a contiguous cutting profile for drilling an initial segment of the wellbore. A driver is then lowered into the casing for connection to the child bit to drill beyond the parent bit. The driver may be configured as a drive bit for drilling through material leftover from a cementing operation prior to connecting to the child bit.

A new system for and a method of deploying a heat exchanger pipe. A bore hole is drilled from an access ditch location to a terminal ditch location using a piloted drill head powered via an umbilical attached to the piloted drill head. A casing is attached to the piloted drill head and disposed about the umbilical into the bore hole from the access ditch location to the terminal ditch location. At the terminal ditch location, the piloted drill head is removed from the casing and the umbilical and a heat exchanger pipe is attached to the umbilical. The umbilical is withdrawn from within the casing deployed in the bore hole to pull the heat exchanger pipe into the casing. The casing is then withdrawn from the bore hole leaving the heat exchanger pipe in the bore hole.

A new system for and a method of deploying a heat exchanger pipe. A bore hole is drilled from an access ditch location to a terminal ditch location using a piloted drill head powered via an umbilical attached to the piloted drill head. A casing is attached to the piloted drill head and disposed about the umbilical into the bore hole from the access ditch location to the terminal ditch location. At the terminal ditch location, the piloted drill head is removed from the casing and the umbilical and a heat exchanger pipe is attached to the umbilical. The umbilical is withdrawn from within the casing deployed in the bore hole to pull the heat exchanger pipe into the casing. The casing is then withdrawn from the bore hole leaving the heat exchanger pipe in the bore hole.

The present invention relates to a downhole drilling method for drilling a well in a formation having a formation pressure. The downhole drilling method comprises providing a drill string having a first part and a second part, the second part being arranged closer to a top of the well than the first part, and the first part having a drilling head in a first end and an annular barrier arranged closer to the top of the well than the drilling head. The annular barrier comprises a tubular metal part for mounting as part of the first part of the drill string, the tubular metal part having an outer face; an expandable metal sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing an inner face of a borehole of the well, each end of the expandable metal sleeve being connected with the tubular metal part; and an annular space between the inner face of the expandable metal sleeve and the tubular metal part, the expandable metal sleeve being configured to expand. The downhole drilling method furthermore comprises drilling the borehole by means of the drilling head; detecting the formation pressure to determine any loss of formation pressure; stopping the drilling; dropping a ball into the drill string; pressurising the drill string until the ball reaches a ball seat arranged opposite or below the annular barrier; expanding the expandable metal sleeve by further pressurising the drill string until the expandable metal sleeve abuts the inner face of the borehole; separating the second part of the drill string from the first part; pulling the second part out of the borehole; and injecting cement into the borehole above the first part to provide a cement plug above the first part. The present invention furthermore relates to a downhole drilling system for performing the downhole drilling method according to the present invention and to a downhole completion system.

In one embodiment, there is provided a system for liner drilling in a wellbore that includes a drill bit, a mud motor, a reamer, a drill pipe work string including an expandable liner hanger running tool, and a thruster coupled to an expandable liner hanger and liner. A release pin may be provided in the expandable liner hanger running tool that can be sheared to de-couple the expandable liner hanger from the expandable liner hanger running tool allowing the drill pipe work string to be removed from the borehole while the liner remains in place. A latch coupling is also provided for coupling the expandable liner hanger running tool to the expandable liner hanger when the drill pipe work string is tripped back into the borehole so the liner drilling can be performed using the thruster until the thruster is at full stroke.

In one embodiment, there is provided a system for liner drilling in a wellbore that includes a drill bit, a mud motor, a reamer, a drill pipe work string including an expandable liner hanger running tool, and a thruster coupled to an expandable liner hanger and liner. A release pin may be provided in the expandable liner hanger running tool that can be sheared to de-couple the expandable liner hanger from the expandable liner hanger running tool allowing the drill pipe work string to be removed from the borehole while the liner remains in place. A latch coupling is also provided for coupling the expandable liner hanger running tool to the expandable liner hanger when the drill pipe work string is tripped back into the borehole so the liner drilling can be performed using the thruster until the thruster is at full stroke.

A carrier pipe is protected from corrosion by being received inside a casing at a location above ground. The casing, which can be formed from a polymer, defines a gap extending around an exterior surface of the carrier pipe. In one embodiment, the gap is substantially filled with a potting material having a corrosion-resistant property. In another embodiment, a self-contained impressed current cathodic protection system is received in the gap. A pull head is installed on the carrier pipe and/or casing for pulling the pipe assembly, including carrier pipe, casing, and elements received in the gap, into an underground bore as a single unit. In some embodiments multiple pipe assemblies are pulled together into the same bore.

The disclosure of this application is directed to a downhole tool comprising a central element/member and a sleeve that is rotatably and orbitally disposed around the central element/member. The sleeve rotates and orbits around the central element/member responsive to fluid flowing through the downhole too. The disclosure is also related to a method of advancing the downhole tool in a well by flowing fluid through the tool.

The disclosure of this application is directed to a downhole tool comprising a central element/member and a sleeve that is rotatably and orbitally disposed around the central element/member. The sleeve rotates and orbits around the central element/member responsive to fluid flowing through the downhole too. The disclosure is also related to a method of advancing the downhole tool in a well by flowing fluid through the tool.