Abstract: An equivalent circulating density (ECD) reduction tool can include a positive displacement fluid motor, and a fluid pump configured to be driven by the fluid motor. The fluid pump can include a fluid inlet and a fluid outlet disposed on respective opposite sides of an external flow restriction. A method of controlling equivalent circulating density (ECD) in a well can include connecting an ECD reduction tool in a tubular string, deploying the tubular string with the ECD reduction tool into the well, thereby forming an annulus between the tubular string and a well surface surrounding the tubular string, and flowing a fluid into the well through the tubular string, the fluid returning from the well via the annulus. The flowing step can include operating a positive displacement fluid motor of the ECD reduction tool, the fluid motor thereby rotating an impeller shaft of a fluid pump.

Abstract: A rotating control device can include a bearing housing, an inner mandrel rotatably supported in the bearing housing, and a barrier having upper and lower portions, the upper portion being secured against rotation relative to the inner mandrel, the lower portion being secured against rotation relative to the bearing housing, the lower portion including annular recesses, the recesses being progressively deeper in a radially outward direction. Another barrier can include upper and lower portions, the lower portion including multiple annular walls, an upper surface of each wall being inclined downward in a radially outward direction. Another barrier can include upper and lower portions, the upper and lower portions having annular walls, the upper portion walls being interdigitated with the lower portion walls, and the upper and lower portion walls being circumferentially discontinuous, whereby gaps are formed between circumferential ends of the upper and lower portion walls.

Abstract: A rotating control device can include a latch assembly with a lock ring that permits displacement of an inner mandrel in one longitudinal direction, and prevents displacement of the inner mandrel in an opposite longitudinal direction. Another rotating control device can include a latch assembly and an equalization valve having an open configuration in which fluid communication is permitted between an exterior and an interior of the rotating control device through the equalization valve, the latch assembly changing from a latched to an unlatched configuration only when the equalization valve is in the open configuration. A method of installing a rotating control device can include releasing a running tool from the rotating control device by producing relative rotation between components of the running tool.

Abstract: A rotating control device can include a latch assembly with a lock ring that permits displacement of an inner mandrel in one longitudinal direction, and prevents displacement of the inner mandrel in an opposite longitudinal direction. Another rotating control device can include a latch assembly and an equalization valve having an open configuration in which fluid communication is permitted between an exterior and an interior of the rotating control device through the equalization valve, the latch assembly changing from a latched to an unlatched configuration only when the equalization valve is in the open configuration. A method of installing a rotating control device can include releasing a running tool from the rotating control device by producing relative rotation between components of the running tool.

Abstract: Conveying a replaceable assembly between latched and unlatched configurations with an outer housing can include connecting the replaceable assembly to a running tool, so the assembly can be conveyed with the running tool, and disconnecting the assembly from the running tool. At least one of the connecting and disconnecting steps can include actuating an iris mechanism. A pressure control device can include an annular seal and a latch that releasably secures the annular seal relative to an outer housing, the latch including a grip member that grips a surface and prevents relative rotation. Another pressure control device can include an annular seal connected to and rotatable with an inner mandrel, and a bearing that permits relative rotation between the annular seal and the outer housing. A structure rotates with the inner mandrel, the structure including a flow inductive profile exposed to a bearing lubricant flow path.

Abstract: A rotating control device can include a latch assembly with a lock ring that permits displacement of an inner mandrel in one longitudinal direction, and prevents displacement of the inner mandrel in an opposite longitudinal direction. Another rotating control device can include a latch assembly and an equalization valve having an open configuration in which fluid communication is permitted between an exterior and an interior of the rotating control device through the equalization valve, the latch assembly changing from a latched to an unlatched configuration only when the equalization valve is in the open configuration. A method of installing a rotating control device can include releasing a running tool from the rotating control device by producing relative rotation between components of the running tool.

Abstract: A well system can include a pressure control device including a releasable assembly, and a running tool including a lock mechanism operable in response to a change in a fluid flow rate through the running tool. A method of retrieving a releasable assembly of a pressure control device can include engaging a running tool with a latch, applying a force from the running tool to deactivate the latch, and changing a fluid flow rate through the running tool. A pressure control device can include a releasable assembly having a passage, and a latch releasably securing the releasable assembly in an outer housing, the latch including a piston having set and unset positions, and the piston being displaceable toward the unset position in response to pressure applied to a port in the outer housing, or in response to displacement of a profile disposed in the passage.

Abstract: A method can include positioning a tubular string in a riser string including an outer housing of a pressure control device and an annular seal operable to prevent flow through an annulus between the tubular and riser strings, the tubular string including an equalization valve and a running tool operable to convey a releasable assembly of the pressure control device through the riser string, and opening the equalization valve, thereby permitting fluid communication between the annulus and a flow passage extending longitudinally through the tubular string. A system can include a riser string including an annular blowout preventer with an annular seal, a tubular string including a running tool and an equalization valve releasably attachable to a releasable assembly including an annular seal, and the equalization valve selectively preventing and permitting fluid communication between a flow passage of the tubular string and an annulus between the annular seals.

Abstract: A method can include latching a well pressure control device releasable assembly in an outer housing, and then rotating a tubular string, thereby disengaging an engagement lug from an engagement profile. A well system can include a pressure control device including a releasable assembly and an outer housing, and a running tool including an engagement lug releasably engaged with an engagement profile of the releasable assembly, and a clutch device that resists relative rotation between the engagement lug and an inner mandrel. A pressure control device can include a bearing assembly that rotatably supports an annular seal relative to an outer case, and an extension attached to the outer case, the extension having an engagement profile including at least two longitudinally elongated sections, one section extending to an end of the extension, and another section being blocked from the end of the extension.

Abstract: A rotating control device can include a latch assembly with a lock ring that permits displacement of an inner mandrel in one longitudinal direction, and prevents displacement of the inner mandrel in an opposite longitudinal direction. Another rotating control device can include a latch assembly and an equalization valve having an open configuration in which fluid communication is permitted between an exterior and an interior of the rotating control device through the equalization valve, the latch assembly changing from a latched to an unlatched configuration only when the equalization valve is in the open configuration. A method of installing a rotating control device can include releasing a running tool from the rotating control device by producing relative rotation between components of the running tool.

Abstract: A pressure control device can include a releasable assembly and a latch including a piston having set and unset positions, and the releasable assembly including a release dog extendable into engagement with the latch. The piston can displace with the extended dog to the unset position. A method of retrieving a releasable assembly can include engaging a running tool with the releasable assembly, changing a fluid flow rate through the running tool, thereby securing the running tool to the releasable assembly, applying a force from the running tool to the releasable assembly, thereby extending a release dog from the releasable assembly, engaging the release dog with a latch of the pressure control device and deactivating the latch, and then retrieving the releasable assembly.

Abstract: A method can include latching a well pressure control device releasable assembly in an outer housing, and then rotating a tubular string, thereby disengaging an engagement lug from an engagement profile. A well system can include a pressure control device including a releasable assembly and an outer housing, and a running tool including an engagement lug releasably engaged with an engagement profile of the releasable assembly, and a clutch device that resists relative rotation between the engagement lug and an inner mandrel. A pressure control device can include a bearing assembly that rotatably supports an annular seal relative to an outer case, and an extension attached to the outer case, the extension having an engagement profile including at least two longitudinally elongated sections, one section extending to an end of the extension, and another section being blocked from the end of the extension.

Abstract: A method can include positioning a tubular string in a riser string including an outer housing of a pressure control device and an annular seal operable to prevent flow through an annulus between the tubular and riser strings, the tubular string including an equalization valve and a running tool operable to convey a releasable assembly of the pressure control device through the riser string, and opening the equalization valve, thereby permitting fluid communication between the annulus and a flow passage extending longitudinally through the tubular string. A system can include a riser string including an annular blowout preventer with an annular seal, a tubular string including a running tool and an equalization valve releasably attachable to a releasable assembly including an annular seal, and the equalization valve selectively preventing and permitting fluid communication between a flow passage of the tubular string and an annulus between the annular seals.

Abstract: Conveying a replaceable assembly between latched and unlatched configurations with an outer housing can include connecting the replaceable assembly to a running tool, so the assembly can be conveyed with the running tool, and disconnecting the assembly from the running tool. At least one of the connecting and disconnecting steps can include actuating an iris mechanism. A pressure control device can include an annular seal and a latch that releasably secures the annular seal relative to an outer housing, the latch including a grip member that grips a surface and prevents relative rotation. Another pressure control device can include an annular seal connected to and rotatable with an inner mandrel, and a bearing that permits relative rotation between the annular seal and the outer housing. A structure rotates with the inner mandrel, the structure including a flow inductive profile exposed to a bearing lubricant flow path.

Abstract: Conveying a releasable assembly between latched and unlatched configurations with an outer housing can include connecting the releasable assembly to a running tool, so the assembly can be conveyed with the running tool, and disconnecting the assembly from the running tool. At least one of the connecting and disconnecting steps can include actuating an iris mechanism. A pressure control device can include an annular seal and a latch that releasably secures the annular seal relative to an outer housing, the latch including a grip member that grips a surface and prevents relative rotation. Another pressure control device can include an annular seal connected to and rotatable with an inner mandrel, and a bearing that permits relative rotation between the annular seal and the outer housing. A structure rotates with the inner mandrel, the structure including a flow inductive profile exposed to a bearing lubricant flow path.

Abstract: A well system can include a pressure control device including a releasable assembly, and a running tool including a lock mechanism operable in response to a change in a fluid flow rate through the running tool. A method of retrieving a releasable assembly of a pressure control device can include engaging a running tool with a latch, applying a force from the running tool to deactivate the latch, and changing a fluid flow rate through the running tool. A pressure control device can include a releasable assembly having a passage, and a latch releasably securing the releasable assembly in an outer housing, the latch including a piston having set and unset positions, and the piston being displaceable toward the unset position in response to pressure applied to a port in the outer housing, or in response to displacement of a profile disposed in the passage.

Abstract: A pressure control device can include a releasable assembly and a latch including a piston having set and unset positions, and the releasable assembly including a release dog extendable into engagement with the latch. The piston can displace with the extended dog to the unset position. A method of retrieving a releasable assembly can include engaging a running tool with the releasable assembly, changing a fluid flow rate through the running tool, thereby securing the running tool to the releasable assembly, applying a force from the running tool to the releasable assembly, thereby extending a release dog from the releasable assembly, engaging the release dog with a latch of the pressure control device and deactivating the latch, and then retrieving the releasable assembly.

Abstract: A rotating control device can include a latch assembly with a lock ring that permits displacement of an inner mandrel in one longitudinal direction, and prevents displacement of the inner mandrel in an opposite longitudinal direction. Another rotating control device can include a latch assembly and an equalization valve having an open configuration in which fluid communication is permitted between an exterior and an interior of the rotating control device through the equalization valve, the latch assembly changing from a latched to an unlatched configuration only when the equalization valve is in the open configuration. A method of installing a rotating control device can include releasing a running tool from the rotating control device by producing relative rotation between components of the running tool.

Abstract: Conveying a releasable assembly between latched and unlatched configurations with an outer housing can include connecting the releasable assembly to a running tool, so the assembly can be conveyed with the running tool, and disconnecting the assembly from the running tool. At least one of the connecting and disconnecting steps can include actuating an iris mechanism. A pressure control device can include an annular seal and a latch that releasably secures the annular seal relative to an outer housing, the latch including a grip member that grips a surface and prevents relative rotation. Another pressure control device can include an annular seal connected to and rotatable with an inner mandrel, and a bearing that permits relative rotation between the annular seal and the outer housing. A structure rotates with the inner mandrel, the structure including a flow inductive profile exposed to a bearing lubricant flow path.

Abstract: A rotating control device can include a latch assembly with a lock ring that permits displacement of an inner mandrel in one longitudinal direction, and prevents displacement of the inner mandrel in an opposite longitudinal direction. Another rotating control device can include a latch assembly and an equalization valve having an open configuration in which fluid communication is permitted between an exterior and an interior of the rotating control device through the equalization valve, the latch assembly changing from a latched to an unlatched configuration only when the equalization valve is in the open configuration. A method of installing a rotating control device can include releasing a running tool from the rotating control device by producing relative rotation between components of the running tool.