Abstract: A multi-lock adapter used to inject high-pressure well stimulation fluids through an independent screwed wellhead includes an adapter pin having a central passageway with an internal diameter at least as large as a passageway through the wellhead. A lockdown flange secures the adapter pin to a casing mandrel of the wellhead. The lockdown flange ensures that stress on connection points to the screwed independent wellhead due to elevated fluid pressures used for well stimulation procedures does not exceed engineered specifications.

Abstract: A threaded union for tubulars used for high-pressure fluid applications includes a unitary nut supported by at least two nut retainer segments received under a top wall of the nut in an annular segment retainer groove in one of the tubulars. The nut retainer segments fully support the unitary nut. The nut retainer segments are held in the annular segment retainer groove by limiting travel of the nut or by securing the nut retainer segments in the segment retainer groove.

Abstract: A plug valve has a valve body, a cage fitted within the valve body and a rotatable plug housed within a cylindrical cavity in the cage, for controlling fluid flow through the valve. The cage has first and second opposed flat side surfaces, each side surface has a port for receiving a replaceable flow-path insert in a fluid-tight seal. In one embodiment, the plug also includes at least one inset seal for sealing the at least one of the ports when the plug is in a closed position to inhibit leakage through the valve at low fluid pressures.

Abstract: A metal ring gasket provides a high-pressure temperature tolerant metal-to-metal seal between subcomponents of a threaded union. The metal ring gasket is received in an annular cavity formed between mating surfaces of the subcomponents of the threaded union. The metal ring gasket is capable of maintaining a fluid seal even at very high temperatures resulting from direct exposure to fire. At high fluid pressures the metal ring gasket is energized because hoop stress induced by the fluid pressure forces the metal ring gasket into tighter contact with the subcomponents of the threaded union.

Abstract: Fracturing heads with one or more replaceable wear-resistant inserts have annular sealing elements for inhibiting fracturing fluids from circulating between the inserts and a main body of the fracturing head. Worn inserts and degraded sealing elements are easily replaced to refurbish the fracturing head without replacing or rebuilding the main body. Service life of the main body is therefore significantly prolonged. In one embodiment, an entire flow path through the main body is lined with wear-resistant replaceable inserts to further prolong the service life of the main body.

Abstract: A slip spool includes radially disposed actuators for radially moving slip blocks between a loose encirclement position in which they surround the tubing string and a cached position in which the slip blocks clear an axial passage of the slip spool. The slip spool further includes axially disposed actuators for axially displacing the slip blocks between the loose encirclement position and an engagement position in which the slip blocks are seated within a slip bowl of the slip spool so that a weight of the suspended tubing string causes the slip blocks to tightly grip the tubing string. The slip spool facilitates positioning and repositioning of the tubing string in the wellbore and can be used for supporting or snubbing a tubing string in a live well bore.

Abstract: A gate valve includes a valve body having a cylindrical passage defining a flow path through the valve, a gate for controlling fluid flow through the valve and a replaceable wear-resistant flow-path liner for in the flow path. The flow-path liner includes a plurality of replaceable wear-resistant inserts, including wear sleeves lining ports of the valve body, valve seats and a gate insert for a flow path bore through the gate. Each replaceable valve seat has a wiper ring for cleaning the gate when it opens and closes. By regularly inspecting and replacing worn-out inserts, the service life of the gate valve can be prolonged and the expense associated with replacing or rebuilding the valve body is avoided.

Abstract: A plug valve has a valve body, a cage fitted within the valve body and a rotatable plug housed within a cylindrical cavity in the cage, for controlling fluid flow through the valve. The cage has first and second opposed flat side surfaces, each side surface has a port for receiving a replaceable flow-path insert in a fluid-tight seal. In one embodiment, the plug also includes at least one inset seal for sealing the at least one of the ports when the plug is in a closed position to inhibit leakage through the valve at low fluid pressures.

Abstract: Fracturing heads with one or more replaceable wear-resistant inserts have annular sealing elements for inhibiting fracturing fluids from circulating between the inserts and a main body of the fracturing head. Worn inserts and degraded sealing elements are easily replaced to refurbish the fracturing head without replacing or rebuilding the main body. Service life of the main body is therefore significantly prolonged. In one embodiment, an entire flow path through the main body is lined with wear-resistant replaceable inserts to further prolong the service life of the main body.

Abstract: A casing mandrel for an independent screwed wellhead includes a seal bore for receiving a fixed-point packoff connected to a high-pressure mandrel of a pressure isolation tool, and a pin thread adapted for engagement with a box thread of a tubing head supported by the casing mandrel.

Abstract: A metal ring gasket provides a high-pressure temperature tolerant metal-to-metal seal between subcomponents of a threaded union. The metal ring gasket is received in an annular cavity formed between mating surfaces of the subcomponents of the threaded union. The metal ring gasket is capable of maintaining a fluid seal even at very high temperatures resulting from direct exposure to fire. At high fluid pressures the metal ring gasket is energized because hoop stress induced by the fluid pressure forces the metal ring gasket into tighter contact with the subcomponents of the threaded union.

Abstract: A hybrid wellhead system is assembled using a plurality of threaded unions, such as spanner nuts or hammer unions, for securing respective tubular heads and a flanged connection for securing a flow control stack to a top of a tubing head spool. The tubing head spool is secured by a threaded union to an intermediate head spool. The intermediate head spool is secured by another threaded union to a wellhead. Each tubular head secures and suspends a tubular string in the well bore. The hybrid wellhead system is capable of withstanding higher fluid pressures than a conventional independent screwed wellhead, while providing a more economical alternative to a flanged, or ranged, wellhead system because it is less expensive to construct and faster to assemble.

Abstract: A multipart frac head with removable components permits the frac head to be refurbished in the field. A bottom leg and inlet ports of the multipart frac head can be replaced.

Abstract: A method of subsurface lubrication facilitates well completion, re-completion and workover while increasing safety and reducing expense. The method involves using a subsurface lubricator mounted to a wellhead of the cased wellbore to lubricate a downhole tool string into the cased wellbore by running a subsurface lubricator through the wellhead and into an upper section of a production casing of the cased wellbore.

Abstract: A low-pressure wellhead system with tubular heads and mandrels secured independently using threaded unions. A casing mandrel is secured to a wellhead by a first threaded union. Likewise, a tubing head spool is secured to the casing mandrel using a threaded union. A tubing hanger is also secured to the tubing head spool using a threaded union. An adapter flange may also be secured to the tubing hanger by a threaded union. Because this low-pressure wellhead is faster and easier to assemble and provides full bore access, there is less rig downtime, thus rendering the well completion process faster and more economical.

Abstract: A subsurface lubricator facilitates well completion, re-completion and workover while increasing safety and reducing expense. The subsurface lubricator includes a bi-directional packoff tool on its bottom end. Short hydraulic cylinders lubricate the subsurface lubricator into the well until the bi-directional packoff tool is in a top end of a casing of the well. High pressure fluid pumped through a side port of a wellhead of the well lubricates the subsurface lubricator into the well.

Abstract: An erosion resistant frac head with a convergence chamber, an expansion chamber and a mixing chamber provides improved resistance to erosion caused by abrasive frac fluids pumped through the frac head. A bottom leg of the erosion resistant frac head may be replaced in the field by field hands.

Abstract: A configurable wellhead system is used to efficiently accomplish well completion, re-completion or workover. The configurable wellhead system includes a permanent fracturing spool that is mounted to a casing head of the well and provides a high pressure seal around a top of a casing of the well. The permanent fracturing spool provides full-bore direct access to the casing without the use of a pressure isolation mandrel. A tubing head is mounted to a top of the permanent fracturing spool to complete the configurable wellhead system. A fracturing spool plug secured in a seal bore of the permanent fracturing spool permits equipment mounted above the permanent fracturing spool to be removed without killing the well or inserting a wireline casing plug.

Abstract: A two-part back cap for a plug valve includes a back cap seal body and a back cap retainer nut. The back cap retainer nut secures the back cap seal body within the plug valve and securely supports the back cap seal body. A gap between an outer periphery of the back cap retainer nut and the back cap seal body permits the back cap seal body to flex and expand with a plug valve body of the plug valve. This ensures that the back cap seals are not stressed and a longer service life results.

Abstract: A multipart frac head with replaceable components permits the frac head to be refurbished in the field. In one embodiment, a bottom leg of the multipart frac head is replaceable. In another embodiment, inlet ports of the frac head are also replaceable.