Wellhead assembly

Claim 2

A wellhead assembly comprising a normally vertical housing provided with a central bore, with an inwardly projecting supporting shoulder, and with means for securing the housing to a surface casing, two or more casing hangers arranged concentrically in the central bore of the housing, the outermost casing hanger being suspended from the inwardly projecting supporting shoulder of the housing, and annular sealing means preventing fluid communication between an annular space around a casing hanger and a central bore, wherein each casing hanger except the innermost one is provided with an inwardly projecting supporting shoulder from which the adjacent smaller casing hanger is suspended, wherein the uppermost end of a smaller casing hanger extends further in the central bore than the uppermost end of a larger casing hanger, wherein the outer diameter of the uppermost end of a smaller casing hanger is smaller than the inner diameter of the uppermost end of a larger casing hanger, and wherein the annular sealing means are arranged between the upper end of each casing hanger and the wall of the central bore.

Claim 3

The wellhead assembly of claim 1, wherein the housing comprises a tubular lower part and a tubular upper part, said parts being detachably connected to each other, wherein the lower part is provided with the inwardly projecting supporting shoulder, and wherein the annular sealing means of each casing hanger is located in the upper part.

Claim 4

The wellhead assembly of claim 1 wherein each casing hanger further includes an annular member having a sealing surface cooperating with the annular sealing means.

Claim 5

The wellhead assembly of claim 3, wherein each annular member is provided with locking means for locking the annular sealing means in vertical direction.

Claim 6

The wellhead assembly of any of one of claims 1-4, wherein the annular sealing means comprises an annular central member having a tapering inner surface and a tapering outer surface, an upper sealing ring and a lower sealing ring, each sealing ring being provided with an inner sealing lip in contact with said tapering inner surface and an outer sealing lip in contact with said tapering outer surface, so as to move the inner sealing lip inward and the outer sealing lip outward upon axial compression of the central member.

Claim 7

The wellhead assembly of any one of claims 1-4, wherein each casing hanger is provided with an outwardly projecting shoulder cooperating with an inwardly projecting supporting shoulder of the adjacent larger casing hanger.

Claim 8

The wellhead assembly of claim 6, wherein for a casing hanger the inwardly projecting supporting shoulder is arranged above the outwardly projecting shoulder.

Claim 9

The wellhead assembly of any one of claims 1-4, wherein each casing hanger is provided with a guiding section below the outwardly projecting shoulder.

Claim 10

The wellhead assembly of any one of claims 1-4, wherein each casing hanger is provided with a bore which is in communication with an annular space around the casing hanger and with an annulus between a casing string suspended from the casing hanger and a surrounding casing string.

Claim 11

A wellhead assembly comprising: a normally vertical housing having a central bore, an inwardly projecting supporting shoulder, and means for securing the housing to a surface casing; two or more casing hangers arranged concentrically in the central bore of the housing, the outermost casing hanger being suspended from the inwardly projecting supporting shoulder of the housing, each casing hanger except the innermost one having an inwardly projecting supporting shoulder from which the adjacent next smaller casing hanger is suspended, the uppermost end of the smaller casing hanger extends further in the central bore than the uppermost end of a larger casing hanger, and the outer diameter of the uppermost end of the smaller casing hanger is smaller than the inner diameter of the uppermost end of the larger casing hanger; and annular sealing means between the upper end of each casing hanger and the wall of the central bore for preventing fluid communication between an annular space around a casing hanger and the central bore.

Claim 12

A wellhead assembly comprising: a normally vertical housing having a central bore, an inwardly projecting supporting shoulder, and means for securing the housing to a surface casing; two or more casing hangers arranged concentrically in the central bore of the housing, the outermost casing hanger being suspended from the inwardly projecting supporting shoulder of the housing, each casing hanger except the innermost one having an inwardly projecting supporting shoulder from which the adjacent next smaller casing hanger is suspended, the uppermost end of the smaller casing hanger extends further in the central bore than the uppermost end of a larger casing hanger, and the outer diameter of the uppermost end of the smaller casing hanger is smaller than the inner diameter of the uppermost end of the larger casing hanger; and annular sealing means between the upper end of each casing hanger and the wall of the central bore for preventing fluid communication between an annular space around a casing hanger and the central bore.

Claim 13

The wellhead assembly of claim 10, wherein the housing comprises: a tubular lower part; a tubular upper part detachably connected to the tubular lower part; and wherein the lower part is provided with the inwardly projecting supporting shoulder and the annular sealing means is located in the upper part.

Claim 14

The wellhead assembly of claim 11, wherein each casing hanger further includes an annular member having a sealing surface cooperating with the annular sealing means.

Claim 15

The wellhead assembly of claim 12, wherein each annular member is provided with locking means for locking the annular sealing means in vertical direction.

Claim 16

The wellhead assembly of claim 13, wherein the annular sealing means comprises: an annular central member having a tapering inner surface and a tapering outer surface; an upper sealing ring displaceable toward the central member; a lowe sealing ring displaceable toward the central member; a lower sealing lip on each of the upper and lower sealing rings in contact with said tapering inner surface; and an outer sealing lip on each of the upper and lower sealing rings in contact with said tapering outer surface; whereby, upon axial compression of the annular sealing means, the inner sealing lip moves inward and the outer sealing lip moves outward.

Claim 17

The wellhead assembly of claim 14, wherein each casing hanger is provided with an outwardly projecting shoulder cooperating with an inwardly projecting supporting shoulder of the adjacent larger casing hanger.

Claim 18

The wellhead assembly of claim 15, wherein for a casing hanger the inwardly projecting supporting shoulder is arranged above the outwardly projecting shoulder.

Claim 19

The wellhead assembly of claim 16, wherein each casing hanger further comprises a guiding section below the outwardly projecting shoulder.

Claim 20

The wellhead assembly of claim 17, wherein each casing hanger is provided with a bore which is in communication with the annular space around the casing hanger and with an annulus between the casing string suspended from the casing hanger and a surrounding casing string.

Claim 21

A wellhead assembly comprising: a normally vertical housing, comprising: a tubular lower part defining a central bore; an inwardly projecting supporting shoulder in the tubular lower portion; a tubular upper part extending the central bore, said tubular upper part being detachably connected to the tubular lower part; means for securing the housing to a surface casing; and a plurality of casing hangers arranged concentrically in the central bore of the housing, the outermost casing hanger being suspended from the inwardly projected supporting shoulder, and the outermost casing hanger and each succeeding casing hanger to the innermost, comprising: an inwardly projecting supporting shoulder from which the adjacent next smaller casing hanger is suspended in a manner such that the uppermost end of the smaller casing hanger extends further in the central bore than the uppermost end of a larger casing hanger and the outer diameter of the uppermost end of the smaller casing hanger is smaller than the inner diameter of the uppermost end of the larger casing hanger; and an outwardly projecting shoulder cooperating with the inwardly projecting supporting shoulder.

Claim 22

A wellhead assembly comprising: a normally vertical housing, comprising: a tubular lower part defining a central bore; an inwardly projecting supporting shoulder in the tubular lower portion; a tubular upper part extending the central bore, said tubular upper part being detachably connected to the tubular lower part; means for securing the housing to a surface casing; and a plurality of casing hangers arranged concentrically in the central bore of the housing, the outermost casing hanger being suspended from the inwardly projected supporting shoulder, and the outermost casing hanger and each succeeding casing hanger to the innermost, comprising: an inwardly projecting supporting shoulder from which the adjacent next smaller casing hanger is suspended in a manner such that the uppermost end of the smaller casing hanger extends further in the central bore than the uppermost end of a larger casing hanger and the outer diameter of the uppermost end of the smaller casing hanger is smaller than the inner diameter of the uppermost end of the larger casing hanger; and an outwardly projecting shoulder cooperating with the inwardly projecting supporting shoulder.