US3038745A - Well head seal with means to limit compression of the seal - Google Patents

Description

June 12, 1962 E. F. CQQKE, JR 3,038,745

WELL HEAD SEAL WITH MEANS TO LIMIT COMPRESSION OF THE SEAL Filed May 2, 1957 EDWARD F- COOKE, JR

INVEN TOR.

ATTORNEY United States Filed May 2, 1957, Ser. No. 656,722 1 Claim. (Cl. 285148) This invention relates to well head seal assemblies and particularly to casing hangers and sealing means for such assemblies.

The principal object of the invention is to provide a novel apparatus for suspending and sealing a casing in a well head assembly.

Another object is to provide such apparatus which operates in such a manner that casing deflection is reduced to a minimum thereby eliminating bottlenecking.

Another object is to provide such apparatus which includes casing slips and a distortable seal arranged in such a manner that sealing is automatically effected when the hanger is positioned around a casing and the weight of the casing released.

Another object is to provide a slip bowl which in addition to supporting the casing slips forms part of the means for sealing the casing within the casing head.

Still another object is to provide a casing suspension and seal device which can be introduced through blowout preventer equipment or the like to a position in a well head to support the casing and provide a seal with the casing head.

A further object is to provide a casing hanger and seal assembly, the arrangement of the combination being such that the weight of the casing is used in a controlled manner to tighten the seal.

A still further object of the present invention is to provide a casing hanger and seal having a slip bowl and easing slips arranged therein to compress gasket means into sealed position between the casing head and the inner casing, the arrangement being such that the weight of the inner casing is used to compress the gasket.

Other and further objects of the present invention will be apparent from the following description, the accompanying drawing, and the appended claims.

In the drawing, there is shown in vertical cross section a casing head having a hanger assembly disposed therein to support an inner casing. The left half of the drawing shows the assembly before the release of the casing with no pressure applied to the packing; the right half of the drawing shows the assembly in supporting position with the casing released and the seal compressed.

Referring now to the drawing, casing head 10, which has a flange 11 for securement to suitable fittings (not shown), is formed with an axial bore 12and a downwardly and inwardly tapered shoulder 13. Arranged in the casing head is a slip bowl 14 having a main cylindrical body fitting into bore 12 and a peripheral tapered portion or seat 15 provided with teeth 16 for engagement with casing head shoulder 13. Slip bowl 14, which consists of a plurality of segments, has at its upper end an inwardly directed flange 17 through which extend axial holes 18. A horizontal shoulder 19 is provided on the inner side of the slip bowl to provide a seat for easing slips 20 as later more fully described. Slips 20 are each atent C formed with a radial flange 21 having threaded holes 22 therein. The inner wall of each of the slips is toothed for engagement with casing 23.

The seal assembly of of the hanger includes a retaining ring 2.4 positioned on bowl flange 17, a compressible annular packing element or seal 25, a compression ring 26, and a plurality of bolts 27, the heads of which abut compression ring 26. The bolts pass through the annular seal and are screwed into holes 22 in the slip flanges.

In operation, the hanger is mounted around the casing 23 and lowered through blow out preventers and valves into the well head body. The weight of the hanger, when the slip bowl 14 contacts the bore shoulder 13, causes the segments of the slip bowl 14 to move inwardly forcing the slips into engagement with the casing 23. The weight of the casing then causes the slips to move downward. A downward pull on the support-ing bolts and compression ring as results and the packing 25 is com pressed and forced radially outward against the bore 12 and radially inward against the casing 23. This action continues until the load is sufficient to cause the bowl teeth 16 to bite into shoulder 13 thus preventing further movement of the slip bowl segments. Thus the slip bowl is prevented from further wedging action against the slips. In many cases it has been found that such further wedging action causes bottlenecking of the casing wall. Downward movement of the slips 2% will continue, however, to cause further compressive forces to be applied to the packing. Such continued movement of the slips will be stopped when flange 21 engages shoulder 19 of the slip bowl. This results in the packing 25 being loaded to efiect a pressure seal and so limits the load applied to the bolts and packing as the additional load on the slips is transferred to the slip bowl.

While there has been hereinbefore described an approved embodiment of this invention, it will be understood that many and various changes and modifications in form, arrangement of parts and details of construction thereof may be made without departing from the spirit of the invention, and that all such changes and modifications as fall within the scope of the appended claim are contemplated as a part of this invention.

What I claim is:

A well casing hanger and sealing assembly comprising a slip bowl adapted to be received by a casing head, said head having an inwardly tapered seat with a cylindrical bore thereabove, the upper portion of the slip bowl being cylindrical and of a dimension to substantially fill the space between a well casing inserted into said head and said casing head, said bowl providing a. seating surface at its upper extremity, said bowl including a plurality of segments circumferentially spaced apart a predetermined distance; each segment being tapered on its outer lower face complementary to said tapered seat; a toothed portion on said complementary tapers adapted to engage said tapered seat to limit movement of the bowl; a radial shoulder on the inner periphery of said bowl; a seal assembly on said seating surface, said assembly including a compression ring spaced axially from said seating surface and a packing ring therebetween; a plurality of slip segments within said bowl each having a radial shoulder thereon above said bowl shoulder, said radial shoulder on the slip segments being normally spaced axially from said bowl shoulder a distance less than the axial thickness aoeams of the uncompressed packing ring; well casing engaging means on the slip segments; substantially axially straight cooperable surfaces on the bowl and slips below said radial shoulders adapted upon abutment to force said slips radially inward into gripping engagement with the pipe, said inward movement limited by said toothed portion on said bowl moving into gripping engagement with said tapered seat, and said radial shoulders cooperating to prevent over compression of said packing ring; and connection means between the compression ring and the slip segments, said connection means serving to force the compression ring toward the slip bowl to expand the packing ring inwardly and outwardly into sealing engagement with the well casing and casing head.

UNITED STATES PATENTS Adair Mar. 15, 1932 Nixon May 3, 1932 Black Aug. 16, 1932 Gordy Jan. 17, 1939 Penick Aug. 26, 1947 Allen May 22, 1951 Mueller Jan. 6, 1953 Allen July 6, 1954 Jones Sept. 14, 1954 Rhodes Feb. 25, 1958 Johnson May 26, 1959 Allen Jan. 12, 1960

Images