A reamer includes a housing, a first reamer block, and a second reamer block. The first reamer block includes a leading wall. A second reamer block includes a trailing wall, the trailing wall including a recess. The leading wall is inserted into or nested in the recess to increase the coverage-to-exposure ratio.

In one aspect the present invention may be said to comprise a drill rod for assembly with other drill rods to form a drillstring used for fluid reverse circulation drilling comprising: an outer drill rod comprising a bore that is tapered at each end, an inner drill rod within the outer drill rod, and a retention member removably coupled to each end of the inner drill rod to retain the inner drill rod between the tapered ends of the outer drill rod.

A technique facilitates formation of a gravel pack along relatively lengthy wellbores. According to an embodiment, a completion system comprises a plurality of screen assemblies. The completion system also has an alternate path system disposed along the plurality of screen assemblies. The alternate path system includes shunt tubes, e.g. transport tubes, coupled together by jumper tubes. An anti-buckling structure is coupled to each jumper tube to prevent buckling when high operational pressures, e.g. operating pressures of 9000 psi or higher, are applied to the alternate path system.

A technique facilitates formation of a gravel pack along relatively lengthy wellbores. According to an embodiment, a completion system comprises a plurality of screen assemblies. The completion system also has an alternate path system disposed along the plurality of screen assemblies. The alternate path system includes shunt tubes, e.g. transport tubes, coupled together by jumper tubes. An anti-buckling structure is coupled to each jumper tube to prevent buckling when high operational pressures, e.g. operating pressures of 9000 psi or higher, are applied to the alternate path system.

A mill including a housing having a fluid bypass pathway, a milling feature at a longitudinal end of the housing, a chamber defined by the housing, and a piston disposed in communication with the chamber, the piston defining a fluid passageway initially aligned with the fluid bypass pathway, the piston responsive to pump pressure to move toward the milling feature, the movement misaligning the fluid passageway with the fluid bypass pathway.

A mill including a housing having a fluid bypass pathway, a milling feature at a longitudinal end of the housing, a chamber defined by the housing, and a piston disposed in communication with the chamber, the piston defining a fluid passageway initially aligned with the fluid bypass pathway, the piston responsive to pump pressure to move toward the milling feature, the movement misaligning the fluid passageway with the fluid bypass pathway.

A cutting bit includes a bit body and high-pressure body with a high-pressure fluid conduit therethrough. The high-pressure body and bit body are joined together. The high-pressure fluid conduit is configured to convey a fluid at greater than 14.5 ksi, and in some embodiments greater than 40 ksi. The high-pressure fluid conduit may direct the fluid through a nozzle in a fluid jet to weaken material, such as an earth formation. The cutting bit includes at least one roller cone and/or blades with cutting elements thereon to remove the weakened material. A cutting bit includes both high and low-pressure fluid conduits, and high and low-pressure fluid nozzles. The high-pressure nozzles receive fluid flow from a downhole pressure intensifier, and a connection between the bit and the downhole pressure intensifier includes rigid connectors, flexible connectors, or a combination thereof.

A packer for anchoring and sealing to a tubular in a well, the packer including a packer element, an anchoring arrangement, a setting mechanism and a release mechanism. The release mechanism holds a thin-walled section of tubing in the packer in tension using a biasing mechanism. On severing the tubing, the bias releases an engagement mechanism which allows the anchor arrangement and the packing element to move relative to the body and thereby unset the packer. An embodiment of a dual bore packer is described. A method of well isolation is described, with an assembly including the dual bore packer. The primary bore forms the short string and a secondary bore forms the long string. By severing the short string the integrity of the long string is maintained to pull lower devices on the long string and the short string does not require tension below the packer to release.

A mill including a housing having a fluid bypass pathway, a milling feature at a longitudinal end of the housing, a chamber defined by the housing, and a piston disposed in communication with the chamber, the piston defining a fluid passageway initially aligned with the fluid bypass pathway, the piston responsive to pump pressure to move toward the milling feature, the movement misaligning the fluid passageway with the fluid bypass pathway.

A mill including a housing having a fluid bypass pathway, a milling feature at a longitudinal end of the housing, a chamber defined by the housing, and a piston disposed in communication with the chamber, the piston defining a fluid passageway initially aligned with the fluid bypass pathway, the piston responsive to pump pressure to move toward the milling feature, the movement misaligning the fluid passageway with the fluid bypass pathway.