US1938020A - Control head and blow-out preventer - Google Patents

Description

Dec. 5, 1933. F. w. HlLD 1,933,020

CONTROL HEAD AND BLOW-OUT PREVENTBR Filed July 31, 1929 3 Sheets-Sheet 1 Dec. 5, 1933. F. w. HlLD 0 CONTROL HEAD AND BLOW-OUT PREVENTER 7 Filed July '51, 1929 s Sheets-Sheet 2 f I 5] 5 .11% I r I (3 38533 0 I I I gwwntoo Dec. 5, 1933. v F. w. HILD ,93

CONTROL HEAD AND BLOW-OUT PREVBNTER V Filed July 31, 1929. v 3 Sheets-Sheet 3 Patented Dec. 5, 1933 CONTROL HEAD AND BLOW-OUT PREVENTER,

Frederic W. Hild, Los Angeles, Calif.

Application July 31, 1929. Serial No. 382,384

2 Claims. (Cl. 166-15) My invention relates to control of fluid flow from wells and appertains more particularly to apparatus for preventing blow-out of fluids used and encountered in the rotary system of drilling.

In this system a power driven rotary machine commonly rotates a hollow drill string consisting of a swivel head, a square or fluted drill stem, a drill pipe and a bit, all suitably secured in seriatum. Frequently, rubber protectors are placed on several joints of the drill pipe to prevent wear of the casing. The rotary machine rotatably engages the drill stem which may move longitudinally through the machine. The drill string is usually suspended in a derrick and moved up or down by cables and suitable tackle blocks; or else the drill string is supported by suitable gripping means such as tapered serrated slips in the rotary machine. An hydraulic pressure pump forces mud fluid downwardly through the drill string; the fluid discharging at the bit and returning upwardly outside the drill pipe and within the pipe or casing which is permanently and immovably installed in the bored hole and usually cemented to the sides thereof. The mud fluid discharges from the casing at the surface. The weight of the mud fluid serves to counteract the underground fluid pressures due to gas or other fluids so that with suitable mechanical means the mud fluid may be utilized to control the flow and pressure of the subterranean fluids.

Several strings of easing concentrically disposed, are required to case a well. The several casing pipes are secured together at the surface of the ground, the end of each inner casing project ing above the next larger surrounding casing. Since the number of strings and their size can rarely be predicted for any well, it follows that except for the outer casing, the diameters of the inner casings and the relative positions of their ends with respect to the outermost casing are matters of uncertainty until installation is made. These uncertainties are reflected in the choice and size and position of drill valves and other blow-out prevention devices. It has been universal practice to secure the available blow-out prevention device to the end of the innermost casing. This has required a difierent size preventer or else a special connecting nipple for each inner casing.

In my co-pending application Serial Number 326,208, filed December 15,1928, for Methods and equipment for blowout prevention, I have shown and described a control head for blowout prevention that is secured to the casing flange or terminal collar of the outermost of several concentrically disposed casings, which terminate within this flange or terminal collar. The flange has a common fluid chamber for all of the casings. It is an object of my invention to provide for concentrically disposed well casings, terminal casing flanges or collars which will nest into one another so that they may be at substantially the same level; thereby any number of strings of easing installed in a Well, may terminate at a predetermined level between the ground surface and derrick floor. Another object is to provide a control head secured to the outermost casing and having a common fluid chamber and common outlet for all of the casings, part of the control head being detachable by breech lock connection.

Another object of my invention, is to provide within a rotary drilling machine, a control head operative either with or without the drill pipe or the drill stem.

Another object is to provide a drill valve within a rotary drilling machine. Another object is to provide a drill valve which may be opened and closed by the rotary machine.

Another object of my invention is to provide a mud discharge valve which shall automatically open or close upon predetermined change of the specific gravity of the fluid flowing through it.

Other objects and advantages of my invention will be apparent from the following description and the accompanying drawings.

Figure 1 is vertical section of the equipment embodying my invention. This shows the several casings terminating in and secured to their respective terminal flanges, the latter being concentrically disposed in a common horizontal zone. The outermost terminal flange contains the successive inner terminal flanges, each seated in the next outer flange. Secured to the outermost flange is the control head which comprises the outlet box, the automatic mud discharge valve 95 and the unitary drill valve and automatic preventer. The drill valve is within the rotary drilling machine which is shown in normal drilling position for rotating the drill stem.

Figure 2, is a horizontal section taken on the line 22 of Figure 1, and shows the breech lock connection of the drill valve preventer and the outlet box.

Figure 3 shows the drive bushing removed from the rotary and thus exposing in plan view, the upper part of the control head and. the op-- erating connection with the rotary table.

Figure 4 is a horizontal section taken on the line 4--4 of Figure 6.

Figure 5 is a part vertical section taken on the line 5-5 of Figure 3.

Figure 6 is a vertical section of the control head within the rotary machine and shows the drill valve engaging the drill pipe to prevent blowout. This shows the drill pipe supported by means of slips in the control head, thus illustrating the use of the latter for the normal drilling operations.

Figure '7 reproduces substantially the arrangement of drill valve secured to the rotary machine and the well casing, shown and described in my aforesaid co-pending application Serial Number 326,208, but'with the added feature shown in Figures '7 and 8 hereof, for operating the said valve by the rotary machine.

Figure 9 is a view in part vertical section of a removable, portable stop plug. It is shown in the drill valve with the gates of the latter closed against the plug, thereby effecting closure of the valve when the drill pipe is removed. This stop plug may be used with either type of valve shown in Figures 1 and '7 respectively.

Referring to the drawings, the rotary machine 10 has a base 1] containing the roller bearings 12 on which the table 13 is rotatably mounted. A gear 14 secured to the table meshes with pinion 15 which is mounted on a drive shaft 16, the shaft being journaled in the base 11 and housing 1'7, which is secured to the base. Power applied through a suitable sprocket or coupling (not shown) on the outer end of shaft 16, will be transmitted by the pinion and gear to rotate the table 13. A drive bushing 18'having octagonal perimeter is seated in a corresponding octagonal seat 19, which is formed in table 13. The drive bushing has a square central opening through which the drill stem 20 may move up and down. Thus rotation of the table 13 is transmitted by the drive bushing to rotate the drill stem. A large central circular opening 21 extends through the rotary table 13 and the base 11, and contains the blowout preventer 22.

The preventer 22 provides within the rotary machine, a unit for performing a number of essential functions. It is the member for receiving the taper slips 23 for supporting the drill pipe 25 in the rotary machine. It effects closure for blowout prevention either with or without the drill pipe or the drill stem. Its flange provides in breech lock form,-fluid tight connection with the outlet box 26, the breach lock enabling simple and speedly connection and disconnection. The preventer as a unit may be lifted and lowered through the rotary machine and the latter may be removed without disturbing the preventer.

The upper half 27 of the unitary preventer 22 comprises the slip ring 28 and the drill valve 29. The slip ring 28 has the tapered slip bore 30 for receiving and setting the slips 23 which grip the drill pipe 25 when the latter is required to be supported in the rotary'machine. The slip bore 30 converges downwardly in the common drilling axis to the straight bore 31 which has the same axis, and has diameter suflicient to afford clearance for the drill stem 20 or the drill pipe protector 32, whichever is the larger.

The drill valve 29 consists of the two valve gates 33 and their respective valve stems 34. The valve gates are contained in valve seat 35 which is a large slot horizontally disposed in the bottom of upper half 2'7 and covered underneath, except in the center, by the lower half 36 of the unitary preventer 22. The upper and lower halves of the preventer are secured to each other by tongues and grooves 37 and by bolts 38 so that their junction is fluid tight. The lower half 36 comprises the plug socket 39 and the flange 40. The downwardly projecting plug socket 39 has the taper bore 41 which convergesupwardly in the common axis to the straight bore 31. Except for this straight bore which is less in diameter than the width of the valve seat 35,the valve seat is completely enclosed by the two halves of the unitary preventer 2 2.

The two valve gates 33 may move toward or away from each other in the valve seat 35; the gates meet at a diameter which is at right angles to their line of movement. Each gate has a semicii cular bore 42 of diameter approximating that of the drill pipe 25. The end faces 43 and the arcuate face 42 of each gate are notched to receive and retain the packing 44, the notches being so disposed as to cause the two valve gates to interlock in tongue and groove at their end faces 43. When the valve g'atesare closed together against a cylindrical object like the drill pipe 25,-the packings 44 in the arcuate faces 42 are forced against the said cylindrical object; at the same time the packings in the end faces 43 are forced together within the interlocking notches, the labyrinth formed by the notches serving to augment the packings in preventing fluid leakage.

Each valve gate 33 is moved into desired position by its own valve stem 34, the two stems being disposed in upper half 27, diametrically opposite each other and parallel to the common axis. Each valve stem 34 rests upon its own valve gate, the flat bottom of the valve stem forming a crank base 45 and terminating in crank pin 46 which projects downwardly into the elongated hole 47 which is located in the outer end of valve gate 33. A pockebjust above the valve gate contains the crank base 45, and a counterbored hole from this pocket through to the top of upper half 2? contains the valve stem 34. The counter-bore forms an annular groove in the pocket that registers with annular tongue 48 on crank base 45, so that pressure on the underside of the valve stem will seat the latter more firmly in its labyrinth seat and prevent fluid leakage past it. The upper free end of the valve stem has a hexagon shaped head, which may be engaged by a socket wrench 49 to rotate valve stem 34 and thereby move the valve gate 33 in the valve seat 35.

The power to rotate the valve stems may be applied to the wrench by hand or by the rotary machine. The two socket wrenches 49 may lie in octagonal seat 19 of the rotary table 13 which when rotated will rotate the valve stems, thereby operating both valve gates 33.

The flange 40 extends radially outward from the plug socket 39, the flange being secured fluid tight to outlet box 26, by annular tongue and groove 50 and by breech lock. The breech lock is substantially a large, single, square thread which instead of being continuous, is cut to form approximately equal segments. Thus considered the flange 40 serves as a rotatable screw having thread segments 51, and the outlet box serves as a stationary nut having thread slots 52. The spaces between the segments permit the flange 40 to be lowered into the outlet box 26, so that the thread segments 51 register with thread slots 52. Then upon rotating the flange through a few degrees, the thread segments andslots engage, the thread angle serving to force the flange downward into its seat in the outlet box. This angular movement may be imparted to the uni- 84 and the cover 85 and has one free end protary preventer 22, and thus to the flange by hand or by the rotary machine or other power equipment in the derrick.

The outlet box 26- has lateral outlets 53, 54 and 55 respectively. The outlet 53 connects with the automatic specific gravity valve 56. Outlet 54 may be used with a suitable valve for bypassing the valve 56 or to take off gas -or other fluid from the outlet box. Outlet 55 may be used as an inlet when it is desired to pump mud directly into the outlet box and the well casing. Outlets 54 and 55 are kept normally closed. Outlet box 26 has bottom flange 57 which is secured fluid tight by tongue and groove 58 and by bolts 59 to the terminal flange 60 of outermost casing 61. The terminal flange 60 is supported by and anchored to suitable foundation 62.

The terminal flange 60 consists of the head 63 and the downwardly projecting collar 64. The collar has thread 65 into which is screwed the threaded end of casing 61. The flat'top surface of the head 63 has groove 58, the headhas two bores 66 and 67 respectively which form the shoulder 68. The bore 66 which is the smaller, has diameter about equal to the inside diameter of casing 61.

Seated in and contained by the terminal flange 60 is the terminal flange 69, which consists of the head 70- and the collar 71. Screwed into thread 72 of the collar 71 is the threaded end of casing '73. The outer circumferential surface of the head 70 is machined to fit the bores 66 and 67 and the shoulder 68 of the terminal flange 60. The head '10 has the two inner bores 74 and '75 respectively which form the shoulder 76. A thread 77 is out part way in the larger bore '75 in-order to receive a suitable cementing head which is used only -during'the cementing operations when setting the casing permanently in the the casing 81.

bored hole.

Similarly, the flange 78 which consists of the head '79 and the collar 'is contained by flange 69. The head 79 is seated in the bores '74 and '75 and shoulder 76' and is threaded for receiving the cementing head. The collar 80 is threaded onto Likewise the flange 82 is contained by and seated in flange '78, the flange 82 being threaded onto the casing 83.

Since much of the weight of each casing is suspended from its terminal flange, it follows that the pressure on the shoulder of the adjacent containing flange in which the inner flange is seated is considerable, thereby forming fluid tight joints between consecutive strings. The pressure increases cumulatively from inner flange to outer flange, being maximum at the outermost flange, which supports the suspended weight of all the inner casings. Furthermore, fluid pressure in the outlet box 26 will be exerted to increase this pressure. v strings will be prevented. It is apparent that upward force exerted on the unitary preventer 22 will be opposed by the combined weight of all of the casings and by the great friction due to the casings being cemented in the bored hole.

The specific gravity valve 56 comprises the body 84, the cover 85 and valvegate 86 and the valve handle 87. The body and the cover are bolted together to form a chamber for the valve gate. The body 84.has flanged inlet 88 which is bolted to outlet 53 of the outlet box 26. The inlet 88 communicates with the valve chamber in the body 84 which contains the swinging valve gate 86. The valve gate is mounted at one of its ends on shaft 89 which is journaled in the body Hence blowout between.

jecting therefrom, for connection with valve handle 87. The valve gate 86 is constructed to be buoyant and may be of wood so as to float in the mud fluid. It has a packing 90, that may serve as a wear strip when against the valve seat 91, which forms the mouth of discharge outlet 92. The valve gate may be weighted by the handle 87 so that the gate will float (as shown in its dotted position in Figure 1) in mud fluid of predetermined specific gravity and to sink when the specific gravity of the fluid passing through the valve becomes less. When thus sinking, the valve gate, being pivoted in one end by the shaft 89, will swing downward and seat itself against the valve seat 91, thereby closing the discharge outlet 92 of the mud valve 56. The discharge outlet curves upward so as to conduct the discharging mud fluid to the level required to float the plug bushing 93 within plug socket 39 during normal operation.

The specific gravity of the mud fluid may lessen because of dilution by water or gas, conversely, when mud of heavy density is added, the specific gravity of the fluid is increased. It is apparent that valve gate 86 will also swing downward automatically to the closed position when the fluid level falls and no fluid is passing through the valve. The handle 87 may actuate a suitable electrical signal 94 by actuating a switch 95 during the downward swing of the valve gate 86,-the signal and the switch being connected by the circuits 96 to a suitable source of electric energy 97.

In my aforesaid co-pending application Serial Number 326,208, I have described a blow-out preventer comprising a buoyant plug bushing slidably mounted on the drill stem and co-operating with the drill valve. The bushing is floatable in the mud fluid in the well casing and when the fluid rises above a predetermined level the bushing is automatically forced by the rising fluid into a suitable conical seat in the drill valve, thereby automatically preventing blow-out of the fluid and the drill stem. In Figure 1 hereof, I

show such a preventer co-operating with unitary preventer 22. It is indicated by the plug bushing 93, which is slidably mounted on drill stem 20 and rotates with the latter within the taper bore 41 of plug socket 39. The bushing 93 is in two parts, the cleavage being vertical for ready assembly on the drill stem. The two parts are held to- .gether by wire wrapping 98. -A collar 99 at the are closed against drill pipe 25, the under faces of the valve gates intercepting the drill pipe protector 32 which rests on the shoulder of drill pipe coupling 100. When the drill pipe is lifted as by the hoisting tackle or the upward force of the well fluids, the protector 32 which is usually made of soft rubber, serves as packing as it is forced and swelled laterally by the compression against drill pipe 20 the drill pipe coupling 100, the valve gates 33 and the bore 31 of the unitary preventer 22. When the protector 32 is not employed, the drill pipe coupling 100 is intercepted by the valve gates 33.

Here again it is evident that the unitary prebore 41.

venter 22 may be readily lifted and lowered through the rotary machine. Also the rotary machine may be removed without disturbing the preventer, which may be left on the well and be employed for the production service.

In Figures '7 and 8, the rotary machine is shown secured to the drill valve 101 which contains the geared valve gates 102, that are shown engaging the drill pipe 25 and the drill pipe coupling 100. To the bottom of the valve housing 103 is bolted the flanged coupling 104 which has inwardly projecting flange 105. Within the flanged coupling and upon the flange is packing 106. The end of casing 107 extends into the flanged coupling 104, through the flange 105 and the packing 106 and is threaded into casing collar 108 so that the packing is between the flange and the casing collar. A pinion 109 meshing with the gear teeth of one of the rotary valve gates 102 is mounted on shaft 110 which is journaled in the valve housing 103. Both the pinion and the shaft are enclosed by the housing with the exception of one end of the shaft which extends outside the housing. A sprocket 111 secured to the projecting end of shaft 110 is connected by chain 112 to a sprocket 113 which floats on the rotary shaft 114. A clutch 115 splined to the rotary shaft 114 may be moved by handle 116 to engage the sprocket 113. It is apparent that power from the rotary shaft 114 may be transmitted to rotate the valve gates 102 into desired position.

In Figure 9, the stop plug 124 is shown inserted in unitary preventer 22 and engaged by the valve 29. The body of the stop plug has the head 117, the flange 118 and the neck 119, joining the two. The head 117 is within the tapered slip bore 30 of the preventer 22, and has diameter larger than straight bore 31 so that it is impossible for the stop plug to fall through into the well. The head is beveled at the bottom as indicated by the surface 120 so that when the valve gates 33 are moved to closed position, they encounter the bevel 120 and impart upward movement to the stop plug 124. The neck 119 which is somewhat less in diameter than the semicircular bore, 42 of the valve gates 33, is within the straight bore 31. The flange 118 which has diameter slightly less than straight bore 31, is within the upper part of tapered socket The packing ring 121 is moulded on the neck 119. The diameter of the relaxed packing ring opposite the valve gates 33 is slightly larger than the drill pipe 25. The diameter of the relaxed packing ring between the valve gates and the flange 118 is slightly less than straight bore 31.

Thus when the valve gates 33 of the drill valve are closed on the stop plug l24,-the packing ring 121 is forced and squeezed against the neck 119 and the flange 118 of the stop plug and against the straight bore 31, the valve gates 33 and the valve gate packing 44, of the unitary preventer 22. A handle 122 is threaded into the head 117. This handle may be a pipe and provide a fluid conducting passage from below the stop plug to a hand valve 123 on the outer end of pipe handle 122. The stop plug 124 may also be used with geared drill valve 101.

, Consideration of the methods and devices I have described herein, shows that my invention provides for utilizing the discharging well fluid for controlling its flow from the well and to prevent blow out: when the hydrostatic pressure of the mud column in the well fails to exceed the underground fluid pressures released by the drill, the mud column will be forced upward, together with the impelling fluid, and both will escape through whatever openings may be available in the mud circulating system. Inadequacy of the mud column can only occur from either or both of two causes; namely, the mud level may fall too low, or the mud may become excessively diluted by gas or water. In either case the specific gravity valve 56 will automatically close before the underground fluid pressures can begin ejectment. Should the mud column have fallen too low, the upward movement of the fluid, once it starts, will accelerate rapidlyand on reaching the outlet box 26, the rapidly moving fluid will quickly force the plug bushing 93 into its seat in preventer 22, thereby closing the only available opening. The immediately resulting fluid pressure in the outlet box will easily overcome the tendency of the valve gate 86 to float, even though the specific gravity of the mud fluid be amply high. The fluid pressure will be exerted to force the valve gate 86 more firmly against the valve seat 91; also the fluid pressure will be exerted to force the casing terminal flanges together more tightly in their respective seats.

Threatened ejectment of the well fluids during drilling is usually preceded by dilution of the mud fluid by gas. The automatic closing of thespecific gravity valve 56, which then occurs and which will be indicated to the drillers in ample time by the signal 94, together with the automatic closing action of the plug bushing 93, provide full protection against blow out.

When withdrawing the drill pipe, the drill stem 20 and plug bushing 93 will have been removed, and the unitary preventer 22 will have been replaced in its seat in the outletbox 26. The mud level will have lowered and consequently the specific gravity valve 56 will have closed automatically. The only available outlet for fluid rising out of the well casing will be the comparatively small annular space between the drill pipe 25 and the straight bore 31 of the preventer 22. This space is controlled by the drill valve 29, so that fluid flow is readily controlled and blow out prevented.

For bringing in the well, the drill string will have been removed and the innermost casing constituting the perforated oil string will have been set, preparatory to running the bailer for removing the mud fluid from the oil string. Immediately upon the final lifting of the bailer, the stop plug 124 may be inserted in the drill valve 29,-and the fluids rising into the outlet box 26 may be readily controlled and conducted therefrom into the flow lines, which with their respective valves, will have been connected to the outlet box and to hand valve 123 of the stop plug 124.

Although I have described several specific embodiments of my invention, it will be obvious to those skilled in the art, that various modifications may be made in the details of construction, the general arrangement, the association of the several co-operating parts and the application of my invention without departing from the spirit thereof or the principles herein set forth.

I claim as my invention:

1. A casing head cover having an axial opening for the passage of a drill string adapted to be rotated by a rotary table, a gate valve supported by said cover and movable transversely of the axial opening, and means for operating said valve, comprising a rotatable shaft having an axis parallel to the axis of the opening, and

a guide formed in the cover, a slot and pin mechanism for moving the gate in the guide, a shaft having an axis parallel to the axial opening and operating said mechanism, and an arm carried by the shaft and adapted to be engaged by a corner of the opening in the rotary table.

FREDERIC W. HILD.

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