US2357411A - Auxiliary flange for control heads - Google Patents

Description

Patented Sept. 5, 1944 AUXILIARY FLANGE Foa CONTROL HEADS Arthur L. Lemmi, Crosby, and Gale E. Nevin,

Houston, Tex., assignors to The National Supply Company, Pittsburgh, Pa., a corporation of Pennsylvania Application February 12, 1942, Serial No. 430,568

(Cl. 285-22)v 1 Claim.

Our invention relates generally to oil well equipment and more particularly to acasing support or control head adapted to be connected to the upper end of a well casing of an oil or gas well for suspending an inner string of casing therein to pack off and seal said inner casing against leakage at its upper end and to control the flow of fluid through said casing.

An object of our inventio-n is to provide a control head assembly adapted to be secured to a plurality of concentrically disposed strings of casing or tubing suspended in a well bore to pack off and seal the space between said casing or tubing independently of the weight of the casing or tubing and their respective suspension means.

In the art of drilling oil or gas wells a relatively large diameter hole is bored into the earths surface to a depth depending upon the formation encountered. The hole is lined with a string of well casing, as near the diameter of the hole as possibley which extends from the bottom of said bore hole to a point slightly above the earths surface. This casing is set in cement at the bottom of the hole and provides a shut-off to prevent water in the surface formation from entering the well.

The well bore is continued into the earths surface using'a smaller diameter drill to a depth also determined by the formation encountered.

A casing to llt this diameter hole is then set concentrically with the outer casing. vA series of concentric casings may be employed during the drilling of the well, since each time the bore is decreased in diameter a casing the size of the last bore is set in cement at the bottom of the I essary sealing means for constraining fluid under pressure between the casing strings and means for testing the effectiveness of said seal.

The principal object of our invention is to provide an auxiliary flange mounted on a casing head and adapted to engage a primary packing element which forms a seal between the auxiliary flange, the inner casing and the casing head and in which is also provided a supplemental sealing means to form a secondary seal about said casing. j

The new combination constituting our invention also contemplates the use of testing means 55 whereby fluid under pressure is introduced into the space between the bore of the auxiliary flange and the inner casing and between the primary and secondary packirigs to determine the security or effectiveness of said seals before the balance of the casing and tubing head structure is mounted in place.

Other objects and advantages of our invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in conjunction with the accompanying drawings illustrating the preferred embodiment of our invention.

It is to be understood that the drawings are by Way of illustration and example only in which:

Fig. 1 is a side elevation, partly in vertical midsection of a control head assembly embodyingl the auxiliary flange feature of our invention.

Fig. 2 is an enlarged elevational view of the auxiliary flange unit, partly in vertical midsection, shown in assembled relation with a fragmentaryportion of the adjacent casing head and tubing hanger support.

In the drawings the numera1 I designates a well casing head body adapted to be secured to the upper end of a well casing 2 by means of screw threads 3 or the like. Side outlets 4 are provided in said head intermedaite its upper and lower ends to allow for connections to takeoil pipes l(not shown).

The casing head body I is provided with an axial bore 5 which merges at its lower end into a downwardly converging bore 6, concentric with said axial bore 5. The upper end of the bore 5 is counterbored as at I forming a shoulder with said bore 5. This counterbore extendsvup- Wardly and in axial alignment With said bore to the upper end of said body.

After the second or inner string of casing 9 has been set it is customary to install a set of hinged slips I0, to suspend and support said casing, which are mounted Within the bore 5 and seated upon the tapered portion ti of said bore in said casing head body I. The upper end of the linner casing is cut off to a predetermined dimension depending upon the type of sealing means to be employed, which in this case will be presently described.

The'exterior of said body is flan-ged, as at Il, I Aat its extreme upper portion to .provide a suitl An abutment ring I4 rests upon the shoulder 8 in the counterbore 1 and is adapted to support a resilient primary packing I5 mounted thereon. A depending annular packing engaging ring I6 is formed integral with the extreme lower end of the auxiliary flange I2 land is adapted to seat upon the packing I5 to compress the same when pressure is brought to bear upon said packing. The ring I8 acts as a packing gland and is formed to freely enter the counterbore 1, as the packing is compressed.

The packing is compressed axially and thereby expanded radially into sealing engagement with the surrounding inner casing 9, the wall of the counterbore 1 andthe joint between the casing head and the auxiliary flange by means of pressure applied to nuts I1 on a plurality of double end through bolts` I8 extending through aligned openings in flange II of the casing head and the annular base ring I3 of the auxiliary flange. This same packing also seals off the space between the interior of the outer casing 2 and the exterior of the inner casing 9. It will be seen that the single seal performs the multiple sealing functions disclosed above.

After the primary packing I5 has been set in sealing engagement as described above, a supplemental packing I9 and gland 20 are inserted into a packing recess 2| in the upper portion of the auxiliary flange I2. sealing contact about the inner casing 9 by means of a plurality of gland actuating screws 22, threaded into an annular anchor ring 23. The said anchor ring is attached to the auxiliary flange by means of screw threads 24 in a counterbore 25, concentric with and formed above said packing recess 2|. This construction forms a secondary seal about the casing 9 and provides additional security to the assembly as well as providing one of the elements required for testing the effectiveness of the seal to be presently described.

A testing port 26 extends from the outer periphery of the base ring I3 of the auxiliary flange to a point 21 in the bore of said flange, midway between the packing engaging ring IB and the lower end of the supplemental packing recess 2 I. A hand pump and pressure gage (not shown) are connected to the testing port through the tapped outlet 28 and pressure is introduced between the primary and supplemental packings. If necessary either or both of these packings may be tightenedat this time to insure a proper seal, after which the testing apparatus is removed and a plug (not shown) is inserted in the tapped outlet 28, thus sealing the port.

Due to the resiliency of the packing I5 and the extreme vibrations to which such assemblies are subjected it is often difficult to maintain a constant sealing pressure on the packing I5 by the sole means of the applied pressure to the nuts I1 bearing against the flange I I and the ring I3. In order to sustain an effective fluid seal under constant pressure and to hold the nuts tight on the double end bolts and thereby maintain an effective seal, a plurality of locking screws 29 spaced at regular intervals between the double end bolts, are employed.

After the nuts on said double end bolts have been set up uniformly so as to provide a fluid tight seal, thus subjecting the packing I5 to a predetermined pressure, the locking screws 29, which are preferably of the hollow headless type, are screwed down through the tapped holes 30 in the base ring I3 and brought to bear against the This packing is urged into top surface 3| of the casing head body I. This effectively locks and secures the assembled packing structure into a rigid unit which resists any 'tendency Ito separate due to vibrations and the like and also precludes further distortion of the packing I5 and change in the packing pressure when supported loads are increased.

After the joint and seal described above have been completed a tubing hanger support 32 is mounted upon and -in `axial alignment with the casing head and auxiliary flange assembly. 'I'he tubing hanger support is formed with a flanged base 33 provided with a plurality of bolt holes in registry with corresponding holes in the casing head flange II and auxiliary flange ring I3. The double end bolts I8, projecting up through the flange ring I3, are long enough to extend through the plurality of holes in the tubing support flange 33. Nuts 34, secured on the upper ends of the double end bolts I8 and bearing against the upper surface of the flange 33 secures the tubing hanger support to the head and flange assembly and unites these three major elements into one rigid unit. The tubing hanger support is sealed to the upper portion of the auxiliary flange through the medium of a conventional metal gasket ring 35. If the tubing hanger support and the casing head flange are to be of the same test pressure, the ring joint 35 is the same as that in the casing head flange. There are cases where it is desirable to use a tubing hanger support of higher test pressure than the casing head flange, and this necessity may not be determined until after the auxiliary flange I2 is installed. In order to .take this into consideration a second ring joint groove 36 is provided in the auxiliary flange.

A tubing 31 is suspended within the tubing hanger support by any suitable means such as from the hanger 38 illustrated in Fig. l. This hanger is prevented from being blown out, in case of extreme well pressure, by a plurality of screw threaded wedge members 39, and is packed off by the conventional packing rings 40.

The hanger 38 is provided with internal threads 4I at its upper end to which a lowering nipple (not shown) may be attached.

Suitable side outlets 42 are provided in the hanger support 32.

A reducing flange or bonnet 43, having a central opening therethrough, is secured to the upper flange 44 of the support 32 and a fluid seal is maintained between these flanges through the customary double end bolts 45, their accompanying nuts 46 and a packing ring 41.

Similar provision is made on the upper surface of the reducing flange or bonnet 43 to accommodate and seal off a christmas tree connection and its several shut off valves (none of which are shown) by means of studs 48 and their accompanying nuts 49 and packing groove 5U.

Having fully disclosed and described our invention, it is to be understood that we do not wish to be limited to the details herein set forth,

but our invention is of the full scope of the appended claim.

We claim:

An. auxiliary flange for sealing off well pressure between a bo-re in a casing head body and an inner string of casing suspended therein by means of slips, a primary packing seated in a recess in said bore above said slips and in sealing engagement with the outer periphery of said casing. said auxiliary flange having its axial bore in sliding contact with the outer periphery of said casing 2,357,411 3 and formed to provide a depending annular packing engaging ring at its lower extremity, the upper portion of said bore being enlarged to form a recess, an auxiliary packing and packing gland in said recess, an annular anchor ring screw threadably attached to said flange within the upper portion of said recess and encircling saidv casing, pressure actuating screws acting throughv said anchor ring for applying compressive pressure to said auxiliary packing through said gland to form a secondary seal about said casing and means to urge and lock said auxiliary'iange into 5 sealing contact with said primary packing.

ARTHUR L. LEMAN.. GiALE E. NEVILL.

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