US2317404A - Casing head - Google Patents

Description

April 27, 1943.

E. W. REARWIN CASING HEAD Filed Nov. 16, 1940 Patented Apr. 27, 1943 CASING HEAD Earle W. Rearwin, Buffalo, N. Y., assignor of one-half to Fred Dobmeier, Buffalo, N. Y.

Application November 16, 1940, Serial No. 365,968

3 Claims.

This invention relates to improvements in casing heads of the type which are used in connection with oil wells to close or seal the upper ends of the well casings.

A casing head of the type now in general use has a screw threaded engagement with the upper end of the tubular casing and is enerally in the form of an inverted cone which permits the oil tubing to be passed through it and to be sealed with packing when in position. These casing heads are each fitted with one or more side openings to which pipes may be connected and which conduct the gas from the well. These coneshaped casing heads do not allow any device or pipe of larger diameter than the oil tubing to pass through it, thus making it necessary to remove the entire casing head whenever anything larger in diameter than the tubing, such for example as a pump barrel, is placed into or pulled out of the well.

When it becomes necessary for any reason to pull the tubing out of a well, means must be provided on the casing head for temporarily supporting the tubing while a length of tubing which has already been pulled out of the well is disconnected, and while the hoisting device is again connected to another part of the tubing. This has made it necessary in th past to construct the casing heads with openings for the tubing of materially less diameter than the diameter of the casing, so that a pump barrel or other enlargement of the tubing could not be removed from the casing except by first unscrewing the casing head. This is objectionable for two reasons. In

the first place, the screw threads of the casing are thus subjected to wear and damage. In the second place, it is desirable to keep the casing head on the casing as long as possible during the pulling of the tubing out of the Well to prevent excessive escape of gas and to prevent entrance of air into the well. Consequently, the casing head is generally left in place until the last length of tubing having a pump barrel or other enlargement thereon is removed from the well. .If the operator makes an error in counting the lengths of tubing which have been removed, and the last length of tubing with the enlargement thereon is pulled against the casing head with considerable force, it frequently happens that the tubing is broken and the enlargement falls down into the well.

One of the objects of this invention is to provide an improved casing head including a part which is in the form of a collar secured to the end of the casing and having an internal 'diameter large enough to permit the passage therethrough of any enlargements on the tubing, and means readily removable from the collar to close the casing head. A further object of this invention is to provide for the collar a plate having an aperture therein of a size suflicient to permit the passage of tubing therethrough and which plate is held on the collar so as to be removed by an enlargement of the tubing engaging the lower face of the plate. A further object of this invention is to provide a casing head of this type with a sealing ring for cooperation with the removable ring, by means of which a gas tight joint can be made with the tubing. A further object of this invention is to provide the removable plate of the casing head with a suitable rib or projection formed to support the holders or clamps usually employed for temporarily holding the tubing.

Other objects of this invention will appear from the following description and claims.

In the accompanying drawing:

Fig. 1 is a sectional elevation of a casing head embodying this invention, the tubing extending through the casing head being shown in elevation.

Fig. 2 is a top plan view thereof, with the tubing shown in section.

Fig. 3 is a sectional elevation thereof, showing parts of the casing head as they appear when the plate is raised by an enlargement of the tubing.

Fig. 4 is a central sectional elevation of the sealing ring of my improved casing head.

Fig. 5 is a central sectional elevation of the plate thereof.

Fig. 6 is a central sectional elevation of the-casing'head collar.

Fig. '7 is a fragmentary sectional elevation on a smaller scale of the upper portion of a well casing and showing in elevation a casing head embodying this invention, and a portion of the elevating means for the tubing.

Fig. 8 is an elevation, on a still smaller scale, of a tube clamping or gripping device employed in connection with the lowering and elevating means for the tubing.

I have illustrated in the drawing one embodiment of my invention, but it is not intended to limit this invention to the particular embodiment shown. In the drawing, I5 represents the well casing, the upper end of which is provided with the usual screw threads for cooperation with a casing head. The oil tubing which extends into the well and through the casing is made of a plurality of lengths of tubing it, the adjacent lengths being connected by means of couplings I I.

In my improved casing head, the screw threads of the casing cooperate with corresponding internal screw threads formed on a collar or sleeve l8, but any other means for securing the collar to the casing may be employed, if desired. This collar is so formed that its internal diameter is not materially smaller than the internal diameter of the casing 15 and preferably the internal diameter of the collar is at least equal to or slightly larger from the well may be conducted from the well by means of these tubes 2|.

The upper end of the collar 18 is provided with an enlargement, such for example as an outwardly extending flange 22, the upper face of which is formed to cooperate with a gasket or suitable pack ng material 24.

To the upper portion of the collar, I apply cover member which has a gas-tight connection with the collar and which also has a substantially central hole or opening through which the tubing, including the couplings between adjacent lengths of tubing, may pass. In the construction illustrated by way'of example, this cover member is in the form of an annular apertured plate 25, which is bolted or otherwise removably secured to the upper end of the collar l8, and this plate has a central aperture 26 which is of materially smaller diameter than the internal diameter of the casing l5, but of sufficient diameter to permit the couplings I! of the oil tubing to pass upwardly through the same.

The underface of the cover member or plate is preferably formed to cooperate with the gasket or seal 24 and the plate may be removably secured to the collar l8 by any suitable means, such for exampl as by means of cap screws 28 extending through holes in the plate 25 and engaging threaded holes in the flange 22 of the collar 18.

When the oil tubing is to be pulled out of the well, these cap screws 28 are removed so that the cover member 25 may be readily lifted from the collar 18, if any enlargement of the tubing strikes the underiace of the plate. It is, however, desirable to maintain this plate in correct axial relation to the collar l8 during the movement of the tubing through the same. Any suitable means may be provided for holding the plate 25 in concentric relation to the collar I8, and at the same time permitting the collar to be moved upwardly when engaged by an en largement of the tubing. In the particular construction shown by way of illustration for this purpose, I have provided the plate 25 with apertures 30 which are adapted to cooperate with pins 3!, see particularly Figs. 2 and 3, which are secured to the flange 22 of the collar 18 and extend upwardly therefrom. These pins or equivalent means for holding the plate 25 in fixed axial relation to the collar I8 are particularly desirable when the tubing is being lowered into the well, since when this is done, the weight of the tubing is at intervals supported on the plate 25 and by maintaining this plate in the fixed relationship at the collar I 8, damage to the packing 24 or to other parts of the casing head is avoided, and the plate 25 also serves to guide the tubing concentrically with the easing l5. H

The cover member 25 is also provided with an. upwardly extending annular rib or projection of any suitable or desired form which forms a support for the clamps or holders which support the tubing at intervals during the elevating or lowering of the tubing. Within this annular rib or projection 35, the plate is .provided with an annular surface 36 which is formed to cooperate with a suitable packing ring or gasket 37. The rib or projection 35 protects the surface 36 and the gasket 31 against damage by the clamps or holders for the tubing.

When the tubing is in place, suitable sealing means are employed for forming a gas-tight seal between the plate 25 and the tubing, and

" for supporting the tubing from the casing head.

In the construction illustrated, I have shown by way of example, a sealing ring 41) positioned on the packing or gasket 31. This sealing ring has an inner diameter only slightly larger than the tubing l6 and any suitable sealing or packing may be employed to form a gas-tight joint between the tubing and the inner surface of the sealing ring. This packing 4| may be made in any usual or suitable manner, for example, by means of candlewicking or string packing. The weight of the tubing presses this sealing material 4| into gas-tight engagement with the tubing and the sealing ring and this weight also holds the sealing ring securely pressed against the gasket 35 to form a seal with the plate 25.

In Figs. 1 and 2, I have shown the parts of my casing head in the positions which they occupy when the tubing is in place in the well, and the well is being operated. The parts of the casing head all form gas-tight joints with each other and with the casing 15. In Figs. 3, '7 and 8, I have illustrated how my improved casing head is used when the tubing is either being pulled from the well or lowered into the same. During this time, the tubing is supported by means of suitable hoisting chains, cables, or the like 45, the lower ends of which engage lugs or projections 46 formed on opposite sides of a tube clamping or gripping device. This gripping device includes two parts pivotally connected to each other at 41 and each part has a substantially semi-circular portion 48, the two semi-circular parts being adapted to extend around the tubing I6. The gripping device is generally so placed on the tubing as to engage the lower edge of a coupling l1. Each half of the gripping or clamping device is also provided with an arm 49, the two arms being adapted to be held together by means of aremovable band or arm holding member 50. Fig. 8 shows the clamping device in gripping relation to a piece of tubing Hi. When the arm holding band or member 50 is removed from the arms 49, these arms can be swung away from each other about the pivot 41 so that the tube gripping member may be disengaged from the tubing. Fig. '7 shows a tube gripping member in engagement with the tubing below a coupling member l1 and also shows the lower edge of the tube. gripping member resting upon the rib or upwardly extending projection 35 of the plate 25. In this figure, the sealing ring 40 has been removed from the casing head.

The operation of my improved casing head, when tubing is being pulled out of a well or p0- sitioned in a well, is as follows: In pulling the tubing out of a well, initially while the parts are in the positions shown in Figs. 1 and 2, the tubing is hoisted until the first coupling member I! engages the sealing ring 40, whereupon this sealing ring will be lifted out of its seating position shown in Figs. 1 and 2. The tubing is hoisted until the first coupling I1 is above the the gripping member rests upon the shoulder 35 of the plate 25. The upper length of tubing is then unscrewed from its coupling 1?, the sealing ring 40 is removed, and the hoisting chains or cables 45 are connected to the tube gripping member which has been pieced below the coupling IT. The tubing is then further hoisted until the next coupling passes upwardly beneath the plate and the operation i then repeated as described. The cap screws 28 are preferably removed at the beginning of the hoisting operation, but at least they should be removed in ample time before the pump or any other enlargement of the tubing H approach the vicinity of the casing head.

As the last part of the tubing is being removed from the well, the usual pump barrel or other enlargement 55 engages the underface of the plate 25 and raises the same from the collar l8, as shown in Fig. 3.

When the tubing is lowered into the well, the plate 25 is placed about the lowest length of tubing and upon the enlargement or pump barrel 55 so that as soon as this enlargement enters into the casing, the plate 25 may be correctly positioned on the collar, for example, by means of the pins 3!. The tubing is then lowered by the hoisting apparatus which holds the tubing by means of a tube gripping member and when this member rests upon the rib or projection 35, the hoisting chains or cables are disconnected from this holding member and a new length of tubing is secured to the coupling 11, with another coupling member at the upper end thereof. The hoisting means are connected to a tube gripping member engaging the upper coupling and the tubing is hoisted sufiiciently to permit the other gripping member upon the shoulder to be disconnected from the tubing, whereupon the tubing is again lowered. Before the last length of tubing I6 is connected to a coupling member, the sealing ring is slipped over this length of tubing so that when the tubing reaches its final position, the sealing ring will be in its operative position relative to other parts of the casing head.

It will be noted that during the hoisting of the tubing and the lowering of the same into the well, the collar 18 remains in its usual operative position and the gas-conducting pipe or pipes 2| need not be disconnected therefrom. Consequently, there is very little wear on the ,collar and also, when it is necessary to pull the tub ing and pumping mechanism out of the well, it is only necessary to remove the cap screws 28. The Wear on the casing head is taken by the cover member 25, which is of inexpensive construction and easily replaced.

The casing head described also has the ad- 7 vantage that it seals the casing equally well against pressure and against suction.

I claim as my invention:

1. A casing head for a well and through which tubing may extend into the casing, including a collar member adapted to be secured to the upper end of the casing and having an internal diameter not substantially less than the internal diameter of said casing, a cover member removably secured to the upper portion of said collar member to form a substantially gas-tight joint therewith and having a substantially central opening of a diameter materially less than that of said collar member, but larger than the outside diameter of said tubing, means for removably securing said cover member to said collar member, upright guide pins secured to one of said members and arranged in spaced relation about the axis of said opening therein and extending substantially parallel to said axis, the other of said members having holes into which said pins extend when said members are in operative relation to each other for releasably holding said cover member and collar member in operative relation to each other independently of said securing means, whereby said cover member may be lifted from said collar member when said securing means are released, and means for use in forming a seal between said cover member and said tubing.

2. A casing head for a well and through which tubing may extend into the casing, including a collar member adapted to be secured to the upper end of the casing and having an internal diameter not substantially less than the internal diameter of said casing, a cover member removably secured to the upper portion of said collar member to form a substantially gas-tight joint therewith and having a substantially central opening of a diameter materially less than that of said collar member, but larger than the outside diameter of said tubing, said collar member having an outwardly extending flange, means connecting said cover member and said flange for securing said cover member to said collar member, a plurality of upright guide pins on one of said members and extending parallel to the axes of said members, the other of said. members having holes extending parallel to said axes to receive said pins for holding said cover member and said collar member in substantially axial alinement and for permitting said cover member to be removed from said collar when said securing means are released, and means cooperating with said cover member and said tubing for use in forming a gas-tight joint therebetween.

3. A casing head for a well and through which tubing may extend into the casing, including a collar adapted to be secured to the upper end of the casing and having an internal diameter not substantially less than the internal diameter of said casing and having an annular outwardly extending flange at the upper end thereof, the upper surface of said flange lying substantially in the same plane as the upper face of said collar to form an enlarged annular bearing surface, a packing ring substantially coextensive with said surface, a cover member having a lower annular face seated on said packing ring and having a substantially central opening of a diameter materially less than said internal diameter of said collar but larger than the outside diameter of said tubing, the upper surface of said cover member having an annular sealing surface immediately adjacent to said opening and an upwardly extending rib arranged about said sealing surface for supporting a tube gripping member used for lowering the tubing into and raising the tubing out of the casing and protecting said sealing surface from damage by said gripping member, means cooperating with said sealing surface to form a seal between said cover member and said tubing, and guide means cooperating with said collar and with the portion of said cover member exterior of said rib for holding said collar and cover member in correct operative relation to each other and for permitting said cover member to be lifted from its operative position.

EARLE W. REARWIN.

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