Abstract: A dual gradient drilling system includes a subsea blowout preventer disposed above a wellhead, the subsea blowout preventer having a central lumen configured to provide access to a wellbore, a lower section of a marine riser fluidly connected to the subsea blowout preventer, a closed-hydraulic positive displacement subsea pump system fluidly connected to the lower section of the marine riser and disposed at a predetermined depth, an annular sealing system disposed above the closed-hydraulic positive displacement subsea pump system, and an independent mud return line fluidly connecting one or more pump heads of the closed-hydraulic positive displacement subsea pump system to a choke manifold disposed on a floating platform of a rig.

Abstract: This disclosure includes riser flange assemblies and related methods. Some assemblies include first and second flanges each defining a plurality of counterbored bolt holes and having a plurality of concave bearing surfaces each disposed around one of the counterbored bolt holes, a plurality of bolts each having a head and a male threaded portion, a plurality of washers each having a convex bearing surface configured to correspond to the concave bearing surface of a bolt hole when one of the bolts extends through the washer and the bolt hole and a plurality of nuts each having a convex bearing surface and a female threaded portion configured to receive the male threaded portion of one of the bolts, the convex bearing surface configured to correspond to the concave bearing surface of a bolt hole when one of the bolts extends through the bolt hole and is received in the nut.

Abstract: This disclosure includes auxiliary-line riser segment assemblies (e.g., with isolation units) that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the auxiliary lines connected (e.g., without welding) below the rotary.

Abstract: A dual gradient drilling system includes a subsea blowout preventer disposed above a wellhead, the subsea blowout preventer having a central lumen configured to provide access to a wellbore, a lower section of a marine riser fluidly connected to the subsea blowout preventer, a closed-hydraulic positive displacement subsea pump system fluidly connected to the lower section of the marine riser and disposed at a predetermined depth, an annular sealing system disposed above the closed-hydraulic positive displacement subsea pump system, and an independent mud return line fluidly connecting one or more pump heads of the closed-hydraulic positive displacement subsea pump system to a choke manifold disposed on a floating platform of a rig.

Abstract: A dual gradient drilling system includes a subsea blowout preventer disposed above a wellhead, the subsea blowout preventer having a central lumen configured to provide access to a wellbore, a lower section of a marine riser fluidly connected to the subsea blowout preventer, a closed-hydraulic positive displacement subsea pump system fluidly connected to the lower section of the marine riser and disposed at a predetermined depth, an annular sealing system disposed above the closed-hydraulic positive displacement subsea pump system, and an independent mud return line fluidly connecting one or more pump heads of the closed-hydraulic positive displacement subsea pump system to a choke manifold disposed on a floating platform of a rig.

Abstract: A dual gradient drilling system includes a subsea blowout preventer disposed above a wellhead, the subsea blowout preventer having a central lumen configured to provide access to a wellbore, a lower section of a marine riser fluidly connected to the subsea blowout preventer, a closed-hydraulic positive displacement subsea pump system fluidly connected to the lower section of the marine riser and disposed at a predetermined depth, an annular sealing system disposed above the closed-hydraulic positive displacement subsea pump system, and an independent mud return line fluidly connecting one or more pump heads of the closed-hydraulic positive displacement subsea pump system to a choke manifold disposed on a floating platform of a rig.

Abstract: This disclosure includes riser-component assemblies and methods of assembling the same that are suitable for managed pressure drilling (MPD) and that can be split apart when using pin connectors to connect auxiliary lines to other auxiliary lines and to components of the riser-component assemblies.

Abstract: This disclosure includes flow spool riser segment assemblies that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the flow spool connected (e.g., without welding) below the rotary.

Abstract: This disclosure includes riser-component assemblies and methods of assembling the same that are suitable for managed pressure drilling (MPD) systems. For example, this disclosure includes integrated flow spool and isolation tool riser components that can be permanently coupled together and that can be configured to pass through a rotary table or other rig equipment.

Abstract: This disclosure includes various connection devices and assemblies, such as telescoping riser joints, that include at least one of the present connection devices. Some of the present connection devices, for example, include a housing having a bore therethrough; a locking ring rotatably movable relative to the housing between a first position and a second position; and an engagement member laterally moveable relative to the bore of the housing between a retracted position and an extended position. In some such connection devices, the locking ring is configured such that movement from the first position to the second position causes the engagement member to move from the retracted position to the extended position.

Abstract: This disclosure includes auxiliary-line riser segment assemblies (e.g., with isolation units) that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the auxiliary lines connected (e.g., without welding) below the rotary.

Abstract: This disclosure includes auxiliary-line riser segment assemblies (e.g., with isolation units) that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the auxiliary lines connected (e.g., without welding) below the rotary.

Abstract: This disclosure includes flow spool riser segment assemblies that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the flow spool connected (e.g., without welding) below the rotary.

Abstract: This disclosure includes auxiliary-line riser segment assemblies (e.g., with isolation units) that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the auxiliary lines connected (e.g., without welding) below the rotary.

Abstract: This disclosure includes auxiliary-line riser segment assemblies (e.g., with isolation units) that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the auxiliary lines connected (e.g., without welding) below the rotary.

Abstract: This disclosure includes riser flange assemblies and related methods. Some assemblies include first and second flanges each defining a plurality of counterbored bolt holes and having a plurality of concave bearing surfaces each disposed around one of the counterbored bolt holes, a plurality of bolts each having a head and a male threaded portion, a plurality of washers each having a convex bearing surface configured to correspond to the concave bearing surface of a bolt hole when one of the bolts extends through the washer and the bolt hole and a plurality of nuts each having a convex bearing surface and a female threaded portion configured to receive the male threaded portion of one of the bolts, the convex bearing surface configured to correspond to the concave bearing surface of a bolt hole when one of the bolts extends through the bolt hole and is received in the nut.

Abstract: This disclosure includes auxiliary-line riser segment assemblies (e.g., with isolation units) that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the auxiliary lines connected (e.g., without welding) below the rotary.

Abstract: This disclosure includes flow spool riser segment assemblies that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the flow spool connected (e.g., without welding) below the rotary.