Rotating blowout preventer

A rotating blowout preventor having at least two rotating stripper rubber seals which provide a continuous seal about a kelly or drilling string having drilling string components of varying diameter. A stationary housing is designed to support a bearing assembly and a clamp cooperates with the housing to secure the bearing assembly in the housing. Chilled water and/or antifreeze may be circulated through the top inner barrel seal of the bearing assembly and lubricant is pumped into the top seal for lubricating the seals and bearings that facilitate rotation of the stripper rubber seals, kelly and drilling string with respect to the stationary housing and pressurize the inner barrel seals and bearings to at least partially offset well pressure.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to drilling heads and blowout preventors for oil and 
gas wells and more particularly, to a rotating blowout preventor mounted 
on the wellhead or on primary blowout preventors bolted to the wellhead, 
to pressure-seal the interior of the well casing and permit forced 
circulation of drilling fluid through the well during drilling operations. 
The rotating blowout preventor of this invention includes a housing which 
is designed to receive a blowout preventor bearing assembly and a 
hydraulic cylinder-operated clamp mechanism for removably securing the 
bearing assembly in the housing and providing ready access to the 
components of the bearing assembly and dual stripper rubbers provided in 
the bearing assembly. A conventional drilling string is inserted or 
"stabbed" through the blowout preventor bearing assembly, including the 
two base stripper rubber units rotatably mounted in the blowout preventor 
bearing assembly, to seal the drilling string. The device is designed such 
that chilled water and/or antifreeze may be circulated through a top 
pressure seal packing box in the blowout preventor bearing assembly and 
lubricant is introduced into the top pressure seal packing box for 
lubricating top and bottom pressure seals, as well as stacked radial and 
thrust bearings. 
Primary features of the rotating blowout preventor of this invention 
include the circulation of chilled water and/or antifreeze into the top 
seal packing box and using a hydraulically-operated clamp to secure the 
blowout preventor bearing assembly in the stationary housing, to both cool 
the pressure seals and provide access to the spaced rotating stripper 
rubbers and internal bearing assembly components, respectively. The clamp 
can be utilized to facilitate rapid assembly and disassembly of the 
rotating blowout preventor. Another primary feature is mounting of the 
dual stripper rubbers in the blowout preventor bearing assembly on the 
fixed housing to facilitate superior sealing of the stripper rubbers on 
the kelly or drilling string during drilling or other well operations. 
Still another important feature is lubrication of the respective seals and 
bearings and offsetting well pressure on key shaft pressure seals by 
introducing the lubricant under pressure into the bearing assembly top 
pressure seal packing box. 
Oil, gas, water and geothermal wells are typically drilled with a drill bit 
connected to a hollow drill string which is inserted into a well casing 
cemented in the well bore. A drilling head is attached to the well casing, 
wellhead or to associated blowout preventor equipment, for the purposes of 
sealing the interior of the well casing from the surface and facilitating 
forced circulation of drilling fluid through the well while drilling. In 
the more commonly used forward circulation drilling technique, drilling 
fluid is pumped downwardly through the bore of the hollow drill string, 
out the bottom of the bore and then upwardly through the annulus defined 
by the drill string and the interior of the well casing and subsequently, 
from the drill string side outlet at the housing. In reverse circulation, 
the drilling fluid is pumped directly through the side outlet and the 
annulus between the drill string and the well casing and subsequently 
upwardly through the drill string bore and from the well. 
Prior art drilling heads typically include a stationary body which carries 
a rotatable spindle operated by a kelly apparatus. One or more seals or 
packing elements, sometimes referred to as stripper packers or stripper 
rubbers, is carried by the spindle to seal the periphery of the kelly or 
the drive tube or sections of the drill pipe, whichever may be passing 
through the spindle, and thus confine the fluid pressure in the well 
casing to prevent the drilling fluid from escaping between the rotating 
spindle and the drilling string. As modern wells are drilled to ever 
deeper depths, greater temperatures and pressures are encountered, thus 
sometimes causing steam or hot water vapor at the drilling head. These 
rigorous drilling conditions pose increased risks to rig personnel from 
accidental scalding, burns or contamination by steam, hot water and hot, 
caustic well fluids. 
2. Description of the Prior Art 
Among the patents which relate to rotating blowout preventors are the 
following: U.S. Pat. No. 4,783,084, dated Nov. 8, 1988, to Biffle; U.S. 
Pat. No. 3,965,987, dated Jun. 29, 1976, also to Biffle; U.S. Pat. No. 
3,868,832, dated Mar. 4, 1975, also to Biffle; U.S. Pat. No. 4,406,333, 
dated Sep. 27, 1983 to Adams; U.S. Pat. No. 4,423,776, dated Jan. 3, 1984, 
to Wagoner, et al; U.S. Pat. No. 4,304,310, dated Dec. 8, 1981, to 
Garrett; U.S. Pat. No. 4,157,186, dated Jun. 5, 1979, to Murray, et al; 
U.S. Pat. No. 4,312,404, dated Jan. 26, 1982, to Morrow; U.S. Pat. No. 
4,398,599, dated Aug. 16, 1983, to Murray; and U.S. Pat. No. 3,128,614, 
dated Apr. 14, 1964, to L. S. Auer. 
It is an object of this invention to provide a rotating blowout preventor 
which is characterized by a blowout preventor housing, a clamp mounted on 
the housing and the housing attached to the well casing, wellhead or other 
blowout preventor equipment to facilitate removably mounting a blowout 
preventor bearing assembly in the housing on a housing gasket, while 
drilling or servicing the well. 
Another object of this invention is to provide a dual stripper rubber 
rotating blowout preventor for containing internal well pressure at the 
well head, which rotating blowout preventor includes fluid ports 
communicating with top pressure seals for cooling, lubricating and 
exerting pressure on the pressure seals and at least partially offsetting 
well pressure application to the lower pressure seals to minimize 
deformation and failure of the pressure seals. 
A still further object of this invention is to provide a new and improved 
rotating blowout preventor which is characterized by a blowout preventor 
bearing assembly fitted with at least two vertically spaced stripper 
rubber seals, the top stripper rubber seal of which is mounted in a 
rotating top rubber pot attached to a rotatable inner barrel and the 
bottom stripper rubber also secured to the rotating inner barrel in the 
blowout preventor and further including a clamp which is capable of 
tightening on the blowout preventor housing and bearing assembly to 
removably secure the bearing assembly inside the housing against a housing 
gasket. 
SUMMARY OF THE INVENTION 
These and other objects of the invention are provided in a rotating blowout 
preventor for containing the internal pressure of a well at the well head 
during well operations, which rotating blowout preventor includes, in a 
most preferred embodiment, a blowout preventor bearing assembly seated on 
a housing gasket in a fixed housing, a hydraulically-operated clamp 
mechanism mounted on the fixed housing and engaging the bearing assembly 
in mounted configuration, which housing is attached to the well casing, 
wellhead or primary blowout preventor, a vertical inner barrel rotatably 
mounted in the bearing assembly and receiving a pair of pressure-sealing 
stripper rubbers and cooling fluid and lubricating inlet ports 
communicating with top pressure seals for circulating chilled water and/or 
antifreeze through the top seals and forcing lubricant into stacked shaft 
bearings and seals to exert internal pressure on the seals and especially, 
the lower seals.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring initially to FIGS. 1 and 2, in a preferred embodiment the 
rotating blowout preventor of this invention is generally illustrated by 
reference numeral 1. The rotating blowout preventor 1 is characterized by 
a housing 2, which is mounted on a conventional casing, wellhead or 
primary blowout preventor equipment (not illustrated) of a well (not 
illustrated), according to the knowledge of those skilled in the art. The 
housing 2 is characterized by an internal housing gasket 47, a mud fill 
line 3, having a mud fill line bore 4 for injecting drilling mud (not 
illustrated) into the housing bore 5 of the housing 2 and circulating the 
drilling mud through the drill string annulus and drill string (not 
illustrated), further according to the knowledge of those skilled in the 
art. A return outlet 8, having a return outlet bore 9, is also provided in 
the housing 2 in conventional fashion for diverting well bore debris, 
according to the knowledge of those skilled in the art, and is fitted with 
a return outlet flange 10, having return outlet flange openings 11. 
Housing flange openings 7 are provided in the conventional housing flange 
6 for bolting the housing 2 to a casing, wellhead or blowout preventor. 
Stabilizing flanges 12 are provided in radially-spaced relationship on the 
housing 2, in order to stabilize the rotating blowout preventor 1 during 
installation. Each stabilizing flange 12 is fitted with a stabilizing 
flange opening 13 for insertion of a rod or tool to manipulate the housing 
2 into position, as deemed necessary. A pair of clamp stops 17 are welded 
or otherwise attached to the housing 2 and project upwardly and outwardly 
from the housing 2 in 180.degree. disposed relationship, for a purpose 
which will be hereinafter further described. 
Referring now to FIGS. 1-5 of the drawings, a clamp 25 encircles the 
housing 2 and includes a pair of curved clamp segments 25a, attached at 
one end by means of a clamp hinge 32 and hinge pin 32a and fitted with a 
clamp lock 28 at the opposite ends thereof. Each clamp segment 25a is also 
fitted with a continuous segment slot 25b, which receives a corresponding 
continuous housing flange 2a, as illustrated in FIG. 3, for securing the 
clamp segments 25a against an outer barrel collar 42a and on the housing 
2. The clamp lock 28 includes a pair of lock segments 29, one of which is 
fitted with internal segment threads 30 and adapted to receive a threaded 
lock bolt 31, having bolt threads 31a that engage the segment threads 30 
of the respective lock segments 29 and secure the clamp 25 in locked 
configuration, as illustrated in FIGS. 4 and 5. Each of the clamp segments 
25a is also fitted with spaced stiffening clamp flanges 26, two of which 
are fitted with lifting sling holes 26a, and in a preferred embodiment of 
the invention, hinge gussets 33 are provided on the clamp hinge 32 and 
clamp segments 25a for strengthening the connection between the respective 
clamp segments 25a and the clamp hinge 32. A clamp segment arm 27 extends 
from each of the clamp segments 25a near the clamp lock 28 and projects 
forwardly for attachment to a corresponding arm plate 27a, by means of a 
companion arm plate bolt 27b. One of the arm plates 27a is attached to the 
cylinder piston 23 of a clamp cylinder 19 and the opposite arm plate 27a 
is secured to a plate bracket 21a, which is mounted on one of a pair of 
cylinder housing plates 21, located on each end of the cylinder housing 20 
of the clamp cylinder 19. A connecting pin 24 pivotally connects one of 
the arm plates 27a to the plate bracket 21a and the opposite arm plate 27a 
to the corresponding cylinder piston 23. Furthermore, the arm plate bolts 
27b are designed to facilitate pivotal attachment of the respective clamp 
segment arms 27 and the corresponding arm plates 27a to allow pivoting 
action between the respective arm plates 27a and clamp segment arms 27, 
responsive to extension and retraction of the cylinder piston 23 in the 
cylinder housing 20. This action opens and closes the clamp 25, as 
illustrated in FIGS. 4 and 5. When the clamp 25 is in the closed 
configuration as illustrated in FIGS. 1 and 4, the lock bolt 31 may be 
inserted in the lock segments 29 to secure the clamp lock 28 and prevent 
inadvertent opening of the clamp 25 by unintentional operation of the 
clamp cylinder 19. In a preferred embodiment of the invention the clamp 
cylinder 19 is designed such that the cylinder housing 20 is sandwiched 
between the spaced cylinder housing plates 21 and is maintained in that 
position by means of housing plate bolts 22, secured by nuts 18, as 
further illustrated in FIGS. 4 and 5. 
Referring now to FIGS. 2, 3 and 5 of the drawings, the housing 2 is 
designed to receive a bearing assembly 41, topped by a top rubber pot 76, 
when the clamp 25 is in the open configuration as illustrated in FIG. 5. 
The top rubber pot 76 includes a pot chamber 77, having pot threads 78 at 
the top inner periphery thereof and a pot chamber shoulder 79 extending 
below the pot threads 78, as further illustrated in FIG. 2. The pot 
chamber 77 is designed to receive a top stripper rubber 100, which 
includes a rubber body 38, secured to a metal insert 35, which is attached 
to a top rubber drive 81, having an o-ring 51 and rubber drive threads 82 
and fitted with upward-standing drive lugs 88. Oppositely-disposed pairs 
of the shaped drive lugs 88 may be fitted with spanner holes 89 for 
insertion of a rod or tool to tighten the top rubber drive 81 on the top 
rubber pot 76 and seal the top rubber drive 81 by means of the o-ring 51 
when the top stripper rubber 100 is lowered into the pot chamber 77 and 
the rubber drive threads 82 engage the corresponding pot threads 78, as 
illustrated in FIGS. 2 and 3. A top rubber drive kelly opening 86 is 
provided in the center of the top rubber drive 81 and communicates with a 
stripper rubber bore 40, extending through the top stripper rubber 100, 
for receiving a drill string and kelly, as hereinafter further described. 
Rubber drive holes 83 facilitate insertion of a tightening tool (not 
illustrated) and tightening the top rubber drive 81 on the top rubber pot 
76. The kelly driver 91 is fitted with spaced driver lugs 92, shaped to 
engage slots between the respective upward-standing drive lugs 88 in the 
top rubber drive 81 and the driver bolts 94 assemble the kelly driver 91, 
as illustrated in FIG. 3. In a preferred embodiment of the invention and 
referring again to FIG. 3 of the drawings, the top stripper rubber 100 is 
molded with the metal insert 35 and is mounted to the top rubber drive 81 
by means of spaced insert bolts 36. This mounting facilitates insertion of 
the top stripper rubber 100 and top rubber drive 81 in concert in the pot 
chamber 77 of the top rubber pot 76, as illustrated in FIGS. 2 and 3. 
As further illustrated in FIGS. 2 and 3, the top end of an inner barrel 43, 
rotatably mounted in the bearing assembly 41, receives the top rubber pot 
76 by means of spaced pot mount bolts 80, as illustrated in FIG. 3. The 
bottom end of the inner barrel 43 receives a bottom stripper rubber 34 
which, like the top stripper rubber 100, has a stripper rubber bore 40 and 
is fitted with a metal insert 35, provided with spaced insert openings 37. 
Preferably, the rubber body 38 of the bottom stripper rubber 34 is secured 
to the metal insert 35 by means of a molding process and the metal insert 
35 is, in turn, attached to a bottom rubber mount ring 45 by means of 
spaced insert bolts 36. The bottom rubber mount ring 45 is secured to the 
bottom of the inner barrel 43 by means of spaced bottom rubber mount bolts 
44, as illustrated in FIG. 3. Accordingly, it will be appreciated from a 
consideration of FIG. 3 of the drawings that the top stripper rubber 100 
and bottom stripper rubber 34 are rotatably mounted on opposite ends of 
the inner barrel 43 in vertically aligned relationship in the rotating 
blowout preventor 1 to receive a kelly 46 that projects through the kelly 
driver 91, top rubber drive 81, stripper rubber bore 40 of the top 
stripper rubber 100, inner barrel 43, stripper rubber bore 40 of the 
bottom stripper rubber 34 and from the bottom of the housing 2. 
Consequently, rotation of the kelly 46 in the drilling operation also 
rotates the top rubber pot 76, top stripper rubber 100, inner barrel 43 
and bottom stripper rubber 34, while the outer barrel 42 and housing 2 
remain stationary. 
Referring again to FIGS. 1-3 of the drawings, a water inlet fitting 14, 
illustrated in FIGS. 1 and 3 and a water outlet fitting 15, illustrated in 
FIG. 2, are seated in the bearing assembly 41 and are provided in 
communication with a passage (not illustrated) provided in the top packing 
box 50, which houses a pair of top seals 55, secured between the fixed 
outer barrel 42 and the rotatable inner barrel 43 of the bearing assembly 
41. Accordingly, chilled water and/or antifreeze may be circulated through 
the water inlet fitting 14 into the passage and from the water outlet 
fitting 15 to cool the top seals 55. Similarly, a lubricant inlet fitting 
16 is also tapped into the bearing assembly 41 to facilitate pressurized 
insertion of lubricant into a lube fissure 53, lying adjacent to the top 
seals 55 for lubricating not only the top seals 55, but also a top radial 
bearing 58 located immediately beneath the top seals 55, a pair of thrust 
bearings 62, spaced from the top radial bearing 58 by a thrust nut 59 and 
a bottom radial bearing 67, as well as a pair of bottom seals 74, 
positioned in a bottom packing box 71 beneath the bottom radial bearing 
67. Additional lube fissures 53 are provided above and below the bottom 
radial bearing 67. A top wear sleeve 52 is seated against the inner barrel 
43 and lies adjacent to the top seals 55, while spaced top plate bolts 49 
serve to secure a top plate 48 to the top packing box 50 which encloses 
the top seals 55 at the top end of the inner barrel 43. Similarly, at the 
bottom end of the inner barrel 43, the bottom seals 74 are secured in 
place against a bottom wear sleeve 72 by means of bottom plate bolts 70, 
that attach a bottom plate 69 to a corresponding bottom packing box 71, 
enclosing the bottom seals 74. Lubricant from the top lube fissure 53 
flows downwardly by application of pressure through the top radial bearing 
58, thrust bearings 62 and bottom radial bearing 67, into the bottom lube 
fissures 53, to thoroughly lubricate the internal sealing components of 
the bearing assembly 41. As further illustrated in FIG. 3, an o-ring 51 is 
seated in each end of the outer barrel 42 and in the top packing box 50 
and bottom packing box 71, respectively, to seal the top packing box 50 
and bottom packing box 71 on each end of the outer barrel 42 responsive to 
tightening of the respective top plate bolts 49 and bottom plate bolts 70. 
In operation, the housing 2 of the rotating blowout preventor 1 is 
initially bolted to a casing or the like in conventional fashion and 
assembled by first removing the lock bolt 31 from engagement with the 
corresponding lock segments 29 of the clamp lock 28 and activating the 
clamp cylinder 19 by means of suitable accessories and controls (not 
illustrated) which are well known to those skilled in the art. Operating 
fluid is then caused to flow selectively through the housing fittings 20a, 
illustrated in FIG. 1, to extend the cylinder piston 23 and open the clamp 
25 from the position illustrated in FIG. 4 to the position illustrated in 
FIG. 5. This operation facilitates insertion of the bearing assembly 41 
and connected top rubber pot 76 into the housing 2, through the open clamp 
25, to seat the outer barrel collar 42a tightly against the housing gasket 
47. Uniform opening of the clamp 25 responsive to operation of the clamp 
cylinder 19 is achieved by initial sliding movement of the right-hand 
clamp segment 25a (as viewed in FIG. 1) on the housing flange 2a of the 
housing 2, illustrated in FIG. 3, by contact between a right-hand clamp 
flange 26 and the right-hand clamp stop 17, which movement forces sliding 
movement of the left-hand clamp segment 25a on the corresponding housing 
flange 2a of the housing 2. When the bearing assembly 41 is seated against 
the housing gasket 47 in the housing 2 as illustrated in FIGS. 1 and 3, 
the clamp cylinder 19 is again actuated, thereby closing the clamp 25 from 
the position illustrated in FIG. 5 to the position illustrated in FIG. 4 
and forcing the clamp segments 25a against the outer barrel collar 42a, to 
seal the outer barrel collar 42a against the housing gasket 47. The lock 
bolt 31 is then threadably reinserted in the respective lock segments 29 
of the clamp lock 28 and the rotating blowout preventor 1 is ready to 
receive a kelly 46, after mounting the kelly driver 91 on the kelly 46. 
The kelly 46 is subsequently "stabbed" into the top rubber drive kelly 
opening 86 and through the top stripper rubber 100 and the bottom stripper 
rubber 34, as illustrated in FIG. 3. The housing 2 is then stabilized, if 
necessary, utilizing the stabilizing flanges 12, in conventional fashion. 
Drilling of the well may then be accomplished by rotating the kelly 46, 
also in conventional fashion and the bearing assembly 41 is removably 
sealed in the housing 2 on the housing gasket 47 against well pressure. 
The rotating blowout preventor of this invention alleviates a common 
problem realized in operating blowout preventors and rotating blowout 
preventors in particular, which is the requirement of changing bearings, 
stripper rubbers and effecting other maintenance to the internal parts of 
the rotating blowout preventor. This problem is minimized in the rotating 
blowout preventor of this invention by simple operation of the clamp 25 to 
provide access to all of the internal parts of the bearing assembly 41, 
including the removable housing gasket 47, top stripper rubber 100 and 
bottom stripper rubber 34. Furthermore, the top seals 55 are maintained in 
a cooler condition by circulating chilled water and/or antifreeze through 
the top packing box 50, and lubricant charged into the top packing box 50 
under pressure is designed to lubricate not only the top seals 55, but 
also the top radial bearing 58, thrust bearings 62, bottom radial bearing 
67 and bottom seal 74 and to lengthen seal and bearing life by at least 
partially offsetting well pressure, particularly in the lower seals. The 
rotating blowout preventor 1 is therefore designed to withstand high well 
pressures in a highly efficient manner with low maintenance down time. 
It will be further appreciated that although a single pair of stripper 
rubbers are described for use in the rotating blowout preventor of this 
invention, in a most preferred embodiment, additional stripper rubbers may 
be added, as desired. Accordingly, while the preferred embodiments of the 
invention have been described above, it will be recognized and understood 
that various modifications may be made therein and the appended claims are 
intended to cover all such modifications without departing from the spirit 
and scope of the invention.