Subsea wellhead system

A seat for supporting at least one pipe hanger within a wellhead of a well, the pipe hanger having a string of pipe attached thereto for suspending the pipe within the well and the wellhead having threads, comprising:

• a tubular body received within the wellhead;
• connection means disposed on said tubular body for releasably connecting said tubular body to the wellhead
• said connection means including threads for threaded engagement with the threads of the wellhead upon rotation of said tubular body;
• and
• shoulder means on said tubular body adapted for engagingly supporting the pipe hanger.

A seat for supporting at least one pipe hanger within a wellhead of a well, the pipe hanger having a string of pipe attached thereto for suspension of the pipe within the well, comprising:

• a tubular body received within the wellhead;
• connection means disposed on said tubular body for releasably connecting said tubular body to the wellhead, said connection means being actuacted upon a 30.degree. rotation of said tubular body;
• and
• shoulder means on said tubular body adapted for engagingly supporting the pipe hanger.

A seat for supporting at least one pipe hanger within a wellhead of a well, the pipe hanger having a string of pipe attached thereto for suspension of the pipe within the well, comprising:

• a tubular body received within the wellhead;
• connection means disposed on said tubular body for releasably connecting said tubular body to the wellhead, said connection means including breech block teeth for supporting said tubular body within the wellhead;
• and
• shoulder means on said tubular body adapted for engagingly supporting the pipe hanger.

A seat for supporting at least one pipe hanger within a wellhead of a well, the pipe hanger having a string of pipe attached thereto for suspension of the pipe within the well, comprising:

• a tubular body received within the wellhead;
• connection means disposed on said tubular body for releasably connecting said tubular body to the wellhead, said connection means including teeth having a profile equalizing the stresses over all of said teeth, said teeth engaging the wellhead to support said tubular body within the wellhead;
• and
• shoulder means on said tubular body adapted for engagingly supporting the pipe hanger.

An apparatus for supporting a hanger, the hanger having a string of pipe attached thereto for suspending the pipe within a borehole, comprising:

• a head member;
• a support member telescopically received within said head member;
• a plurality of circumferentially spaced-apart thread segments on the inner circumference of said head member and a plurality of circumferentially spaced-apart thread segments on the outer circumference of said support member;
• said thread segments on each of said head and support members being in alignment with correlating spaces between said thread segments on the other said member, said thread segments being engaged with each other upon rotation of said support member with respect to said head member to prevent said members from moving axially apart upon the application of an axial force thereon;
• and
• said support member having shoulder means for engaging and supporting the hanger to suspend the pipe within the borehole.

An apparatus for supporting a pipe hanger, the hanger having a string of pipe attached thereto for suspending the pipe within a well, comprising:

• a head member;
• a support member insertable into said head member;
• tooth means provided on each of said head and support members for releasably connecting said members together upon said support member being rotated with respect to said head member;
• said tooth means comprising a plurality of spaced groupings of teeth, said groupings of said support member being adapted to pass intermediate said groupings of said head member during insertion of said support member into said head member.

A well apparatus for supporting a plurality of stacked pipe hangers, each of the pipe hangers having a string of pipe attached thereto and suspending such pipe within a wellbore, comprising:

• a head member;
• a support member received within said head member and having a first bearing area to engage and support the lowermost stacked pipe hanger;
• tooth means provided on each of said head and support members for releasably connecting said members together, said tooth means having a second bearing area for supporting said support member on said head member;
• said first and second bearing areas each having sufficient area whereby the load of the pipe hangers and suspended pipe together with the working pressure of the well does not substantially exceed the material yield strength in vertical compression of said support and head members.

A seal assembly disposed on a shoulder of a tubular member slidingly received within a bore of another member for providing a metal-to-metal seal between the tubular member and the interval wall of the bore, comprising:

• a plurality of frustoconical-shaped metal rings stacked in series, each ring alternating in frustoconical taper;
• an abutment member mounted on the shoulder of the tubular member;
• an actuator member reciprocally mounted on the tubular member, said abutment member and said actuator member having correlative, oppositely disposed surfaces engaging the end rings of said stack upon sealing engagement;
• annular metal connector links disposed between adjacent metal rings and between said actuator and abutment members and adjacent metal rings, said metal connector links having radial thicknesses smaller than the radial thicknesses of the ends of adjacent metal rings to form bend points;
• said metal rings, abutment member, and actuator member having an outer diameter smaller than the diameter of the bore;
• actuation means for applying an axial force on said actuator member causing said actuator member to engage said stack of metal rings and bend said metal links at said bend points thereby moving the inner and outer ends of said rings into metal-to-metal sealing engagement with the tubular member and the internal wall of the bore.

A seal assembly disposed above a lock ring on the shoulder of a hanger slidingly received within a bore of a wellhead for providing a metal-to-metal seal between the hanger and the wellhead, comprising:

• an integral annular body having an upper annular portion, a medial portion, and a lower annular portion;
• said upper annular portion being reciprocally disposed on the hanger;
• said medial portion having a series of frustoconical links with an upper edge integrally connected to a lower peripheral edge of said upper annular portion and a lower edge integrally connected to an upper peripheral edge of said lower annular portion, said links having inner and outer ends;
• said lower annular portion being disposed above the lock ring and having a cam surface for camming the lock ring into engagement with the wellhead;
• actuation means for moving said body toward the lock ring and camming the lock ring into engagement with the wellhead and compressing said medial portion between said upper and lower annular portions thereby deforming said links of said medial portion to larger cone angles such that said inner and outer ends of said links of said medial portion move into metal-to-metal sealing engagement with the hanger and wellhead.

A seal assembly disposed on a casing hanger mounted within a wellhead for establishing a seal between the casing hanger and the wellhead, comprising:

• upper, medial and lower metal rings stacked in series, said medial metal ring having a frustoconical taper in a direction opposite the frustoconical taper of said upper and lower metal rings adjacent thereto, each of said rings having inner and outer rims;
• an abutment member disposed below said lower metal ring for engagement with the casing hanger;
• an actuator member disposed above said upper metal ring and reciprocally mounted on the casing hanger;
• said metal rings, abutment member, and actuator member having an outer dimension smaller than the diameter of the wellhead bore;
• first annular metal links disposed between said upper and medial rings and said medial and lower rings, and second annular metal links disposed between said actuator member and upper ring and between said lower ring and abutment member;
• said metal links having a thickness smaller than that of said adjacent rings and members to form annular channels and bend points;
• said rings having center portions providing resistance to bending upon actuation of the seal assembly;
• said stack of metal rings and links being disposed between said abutment member and said actuator member;
• actuation means for compressing said metal rings and links between said actuation and abutment members causing the movement of said actuator member toward said abutment member and said annular links to bend at said bend points;
• said inner and outer rims of said metal rings moving radially inward and outward, respectively, for establishing metal-to-metal sealing contact with the casing hanger and wellhead.

Apparatus for actuating elastomeric and metal-to-metal seals disposed within the annulus formed by a wellhead and a casing hanger and above a shoulder on the casing hanger, comprising:

• an actuator member having a portion thereof extending into the annulus above and engaging the seals;
• torque transmission means engaging said actuator member to transmit torque and rotate said actuator member;
• said actuator member threadingly engaging the casing hanger whereby as torque is transmitted to said actuator member in one direction, said actuator member travels downwardly on the casing hanger and compresses the seals between the actuator member and the shoulder on the casing hanger to energize the elastomeric seal and seal the annulus against fluid flow and to energize the metal-to-metal seals into metal-to-metal sealing engagement with the wellhead and casing hanger;
• hydraulic means for applying hydraulic pressure to the seals and said actuator member to further compress the seals between the actuator member and the shoulder on the casing hanger whereby the metal-to-metal seal is further energized into metal-to-metal sealing engagement with the wellhead and casing hanger;
• said actuator member following the actuation of the seal downward on the casing hanger to prevent the release of the seals upon the removal of the hydraulic pressure.

A tool on a pipe string for lowering a casing hanger and casing into a subsea wellhead and actuating a seal and holddown assembly disposed between the wellhead and the casing hanger, comprising:

• a mandrel having one end connected to the pipe string and the other end received within the casing hanger;
• a skirt member disposed on said mandrel;
• torque transmission means on said skirt member disposed on and in engagement with the seal and holddown assembly;
• a sleeve member telescopingly received within the annular chamber formed between said skirt member and mandrel, a portion of said sleeve member extending between said mandrel and the casing hanger;
• and
• latch means disposed on said sleeve member and actuated by said mandrel for supporting and lowering the casing hanger and casing and for realeasably connecting said mandrel to the casing hanger.

A tool for lowering a casing hanger into an underwater wellhead, comprising:

• a mandrel adapted for threaded engagement at its upper end with a pipe string and dimensioned at its lower end to be received in the casing hanger;
• a sleeve member reciprocably mounted on said mandrel and having a portion thereof disposed between said mandrel and the casing hanger;
• said sleeve member and mandrel having opposing shoulders for retaining said sleeve member on said mandrel;
• movable latch means disposed on said sleeve member portion disposed between said mandrel and casing hanger for engaging the casing hanger and connecting said mandrel to the casing hanger;
• said mandrel having a latch means holding portion and a latch means release portion, said latch means holding portion and said latch means having cooperable means for urging said latch means into engagement with the casing hanger, and said mandrel having a first position relative to said sleeve member and latch means where said latch means is engaged with the casing hanger and said latch means holding portion of said mandrel prevents said latch means from moving out of engagement with said casing hanger and is movable to a second position where said latch means release portion of said mandrel is adjacent said latch means and permits said latch means to be moved out of engagement with and released from said casing hanger.

Apparatus for latching a casing hanger within a wellhead and for sealing the annulus formed between the casing hanger and wellhead, comprising:

• a seal and holddown assembly threadingly connected to the casing hanger, said assembly including a rotating member threadingly engaged with the casing hanger, a stationary member disposed on said rotating member, and a latch member disposed on the casing hanger below said stationary member;
• said rotating member, stationary member and latch member being received within the annulus formed by the casing hanger and wellhead;
• said stationary member having an upper actuator portion, a medial seal portion, and a lower cam portion, said upper, medial and lower portions being an integral metal member, said upper actuator portion being rotatably mounted on said rotating member;
• said medial seal portion including a series of frustoconical links alternating in frustoconical taper, said links being integrally connected by reduced thickness connector links forming bend points, said medial seal portion expanding radially upon compression as said connector links bend at said bend points causing said frustoconical links to form a metal-to-metal seal with the casing hanger and wellhead to seal the annulus;
• a running tool connected to the casing hanger, said tool including a torque transmission member affixed thereto and extending into the annulus, said torque transmission member engaging said rotating member for applying torque to said rotating member upon the rotation of said running tool, said rotation of said running tool causing said rotating member to thread onto the casing hanger and said seal and holddown assembly to travel downwardly into the annulus;
• said lower cam portion expanding said latch member into holddown engagement with the wellhead and said medial seal portion being compressed between said upper and lower portions to form the metal-to-metal seal with the casing hanger and wellhead upon said downward travel of said seal and holddown assembly.

A well apparatus for suspending piper within a well, comprising:

• a wellhead having a bore therethrough, said wellhead having a first annular shoulder with an annular lockdown groove disposed thereabove;
• a casing hanger having an annular bearing surface for landing on said first annular shoulder and a latch member disposed on a second annular shoulder on said casing hanger above said bearing surface and adjacent said lockdown groove in the landed position;
• a seal and holddown assembly disposed on said casing hanger above said latch member, said seal and holddown assembly including a rotating member and a stationary member;
• said rotating member threadingly engaging said casing hanger and said stationary member being rotatably mounted on said rotating member, said stationary member being received in the annulus formed by said casing hanger and wellhead;
• said stationary member having a seal portion and a cam portion, said cam portion engaging said latch member;
• torque transmission means for rotating said rotating member on said casing hanger and causing said rotating member and stationary member to travel downwardly into the annulus;
• said cam portion camming said latch member into said lockdown groove for the holddown of said casing hanger within said wellhead;
• said seal portion being compressed against said cam portion by the downward movement of said rotating member, said seal portion expanding radially to sealingly engage said casing hanger and said wellhead to seal off the annulus;
• hydraulic means for applying hydraulic pressure above said seal portion to said stationary portion whereby said seal portion is further expanded and energized into sealing engagement with said wellhead and casing hanger;
• and
• said rotating member moving downward on said casing hanger upon the further actuation of said seal portion, said rotating member preventing the release of said seal portion upon the removal of hydraulic pressure by said hydraulic means.

A well apparatus for engaging a latch member on a casing hanger shoulder to lock down a casing hanger landed within a wellhead and for sealing the annulus formed by the casing hanger and wellhead, comprising:

• a rotating member threadingly engaging the casing hanger and being received in the annulus;
• a stationary member having an upper actuator portion, a medial seal portion, and a lower cam portion;
• said upper, medial, and lower portions being an integral metal member, said upper actuator portion being rotatably mounted on said rotating member;
• said stationary member being received in the annulus formed by the casing hanger and wellhead, said lower cam portion engaging the latch member;
• torque transmission means engaging said rotating member to transmit torque and rotate said rotating member, said rotating member moving downwardly on the casing hanger causing said lower cam portion to cam the latch member into holddown engagement with the wellhead, said medial seal portion being compressed against the lower cam portion which is in engagement with the latch member on the casing hanger shoulder and sealingly engaging the casing hanger and wellhead to seal off the annulus and permit the application of hydraulic pressure therein;
• hydraulic means for applying hydraulic pressure to said stationary member to further compress and energize said medial seal portion to further expand into sealing engagement with the casing hanger and wellhead;
• and
• said rotating member following the further actuation of said medial seal portion downward on the casing hanger to prevent the release of said medial seal portion upon the removal of said hydraulic pressure.

A well apparatus for suspending pipe within a borehole, comprising:

• a wellhead member;
• a seat member telescopingly received within said wellhead member, said seat member having an upwardly facing annular frustoconical shoulder;
• tooth means provided on said wellhead member and seat member for releasably connecting said seat member within said wellhead member upon said seat member being rotated less than 360.degree.;
• a hanger member attached to the top of the string of pipe, said hanger member having a downwardly facing bearing surface engaging said shoulder of said seat member, said bearing surface and said shoulder having a full 360.degree. circumferential contact;
• port means extending through said hanger member and around said bearing surface.