US20040140088A1

US20040140088A1 - Variable choke assembly

Info

Publication number: US20040140088A1
Application number: US10/346,225
Authority: US
Inventors: Ibrahim Mentesh; Carl Baenziger
Original assignee: Carpenter Advanced Ceramics Inc
Current assignee: Carpenter Advanced Ceramics Inc
Priority date: 2003-01-17
Filing date: 2003-01-17
Publication date: 2004-07-22
Also published as: WO2004067907A1; AR042896A1

Abstract

A pressure reducing apparatus for controlling the pressure of oil is provided. The apparatus has ceramic components that resist wear caused by sand and debris in the oil. In one embodiment of the invention, the apparatus has a hollow body having an upstream channel, a downstream channel, and a pressure reducing chamber between the upstream channel and the downstream channel. The pressure reducing chamber has a longitudinal axis and contains a disk that is rotatable on the longitudinal axis of the pressure reducing chamber. The disk has a sidewall that abuts the upstream channel and a bottom end that abuts the downstream channel. The sidewall has a height that varies along the circumference of the disk. The disk is rotatable within the pressure reducing chamber so that the height of the sidewall facing the upstream channel can be varied to throttle the flow of oil from the upstream channel.

Description

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §120 from U.S. application Ser. No. 10/130,651, filed as International Application No. PCT/US00/32150 on Nov. 28, 2000, which is hereby incorporated herein by reference.[0001]

FIELD OF THE INVENTION

This invention relates generally to flow components for high pressure oil wells, and in particular to the use of ceramic material in wear components for a pressure reducer assembly for such wells.

BACKGROUND

Many oil well facilities around the world operate under high pressure. In other words, the pressure within the well is sufficiently high (e.g., 3000 to 5000 psi) to carry the crude oil to the surface without pumping. Unless restricted, the crude oil flows to the surface at a high velocity and contains sand and other debris which erodes the interior surfaces of the oil well piping components. In order to limit the amount of sand and debris that is carried with the extracted oil, the high well pressure is maintained in the exit piping by using a pressure reducer at the head end of the well. For instance, a six inch inner diameter well pipe is reduced to three inches through a series of narrow channel pipe components. The flow channel is then further reduced to less than one inch, or even less than one-half inch, in the pressure reducer assembly.

The known pressure reducing devices are made of carbon steel and have tungsten carbide inserts to line the inside surfaces of the flow channels. The abrasive oil-and-sand mixture not only wears away the inside wall of the flow channels, but also backwashes around the outside diameter of the flow reducer and wears away the steel body of the flow reducer, resulting in gross failure of the reducer itself. Often, the metal housing surrounding the flow reducer is severely worn as well. Continuous erosion of the pressure reducer over time results in a slow and continuous loss of desired operating pressure until gross failure requires replacement. This loss in operating pressure causes an ever-increasing sand content, resulting in less efficient oil production. Eventually, the oil line must be shut off, and the entire pressure reducer device must be disconnected from the line and replaced.

The average life of known flow reducers is about 4 to 12 weeks. Oil well downtime to replace a pressure reducer and/or other components, is usually four to eight hours. Since high pressure oil wells typically produce about 5,000 to 12,000 barrels of oil a day, the downtime associated with replacement of a pressure reducer can result in a significant loss of oil production. It is readily apparent that the present construction of oil well pressure reducing assemblies leaves something to be desired with respect to wear resistance, useful life and serviceability.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, a pressure reducing apparatus is provided that has an extended operating life. The internal components of the apparatus are made entirely of wear resistant materials that minimize abrasion caused by sand and other debris in oil. In one embodiment of the invention, the apparatus has a housing that forms an upstream channel and a downstream channel. The housing has a port that fluidly connects the housing with the upstream channel. A disk disposed in the housing is rotatable between a first orientation in which the port is substantially obstructed by the disk and a second orientation in which the port is substantially unobstructed by the disk. The disk has a side wall that covers the port when the disk is rotated to the first orientation to substantially prevent fluid in the upstream channel from entering the housing. As such, the disk is rotatable to throttle the flow of oil and alter the pressure in the pressure reducing assembly.

DESCRIPTION OF THE DRAWINGS

The foregoing summary as well as the following description will be better understood when read in conjunction with the figures in which: [0007]
FIG. 1 is a side elevation view of a pressure reducing assembly for a high pressure oil well; [0008]
FIG. 2 is a side elevation view in partial cross section showing the interior of the pressure reducing assembly of FIG. 1 as viewed along line [0009] 2-2 thereof;
FIG. 3 is a cross-sectional side view of a ceramic liner used in the upstream channel of the pressure reducing assembly of FIG. 2, as viewed along line [0010] 3-3 thereof;
FIG. 4 is a cross-sectional side view of an alternative embodiment of the ceramic liner shown in FIG. 3; [0011]
FIG. 5A is side view of a direction changing cavity liner used in the pressure reducing assembly shown in FIG. 2; [0012]
FIG. 5B is an end view of the direction changing cavity liner shown in FIG. 5A as viewed along [0013] line 5B-5B thereof;
FIG. 6A is a side view of a key plate liner used in the pressure reducing assembly shown in FIG. 2; [0014]
FIG. 6B is an end view of the key plate liner shown in FIG. 6A as viewed along [0015] line 6B-6B thereof;
FIG. 7 is a cross-sectional side view of a downstream cylindrical liner used in the pressure reducing assembly of FIG. 2, as viewed along line [0016] 7-7 thereof;
FIG. 8 is a side view of a ceramic flow reducer used in the pressure reducing assembly shown in FIG. 2; [0017]
FIG. 9 is a side view of an alternative embodiment of the ceramic flow reducer shown in FIG. 8; [0018]
FIG. 10 is a side elevational view in cross section showing a spool adapter assembly used in the pressure reducing assembly of FIG. 1 as viewed along line [0019] 10-10 thereof;
FIG. 11 is a side elevation view of a second embodiment of a pressure reducing assembly according to the present invention; [0020]
FIG. 12 is a cross-sectional side view of a ceramic liner used in the upstream channel of the pressure reducing assembly of FIG. 11, as viewed along line [0021] 12-12 thereof; and
FIG. 13 is a cross-sectional view of a downstream liner used in the pressure reducing assembly of FIG. 11, as viewed along line [0022] 13-13 thereof.
FIG. 14 is a side perspective view in partial cross section showing the interior of a third embodiment of the pressure reducing assembly of FIG. 1 as viewed along line [0023] 2-2 thereof;
FIG. 15 is an exploded perspective view of the pressure reducing assembly of FIG. 14. [0024]
FIG. 16 is a detailed exploded perspective view of the valve assembly used in the pressure reducing assembly of FIG. 14.[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings wherein like reference numerals indicate identical or corresponding parts among the several views and in particular to FIG. 1, there is shown a pressure reducing assembly for a high-pressure well head. For purposes of orientation, the oil flow originating from the well flows through the pressure reducing assembly according to the present invention and toward the oil process piping in the direction shown by the arrows. A [0026] pressure reducing valve 10 is connected through an isolation valve 19 to a well head manifold 25. The downstream side of pressure reducing valve 10 is connected to a first spool adapter 20, which is connected to a second spool adapter 30. The second spool adapter 30 is connected to the piping that leads to the oil processing facilities (not shown).
Referring now to FIG. 2, the [0027] pressure reducing valve 10 has a metallic body that includes an upstream channel 11, a direction-changing cavity 16, a downstream channel 17, and a key-plate recess 18. A pressure reducer 40 is disposed in the downstream channel 17 and has a hex head 42 and a sealing shoulder 43 that extend into the direction-changing cavity 16, adjacent the upstream channel 11. An upstream channel liner 50 is disposed in the upstream channel 11 and a downstream channel liner 80 is disposed in the downstream channel 17. The channel liners 50 and 80 prevent erosion of the inner walls of the channels 11 and 17, respectively, by the oil/sand mixture flowing from the oil well. A direction-changing cavity liner 60 is situated in the direction-changing cavity 16 to prevent erosion and wear of the inner wall of the direction changing cavity 16. A key plate liner 70 is disposed in a key-plate recess 18 situated at an end of the direction-changing cavity 16 adjacent the downstream channel 17. The key plate liner 70 prevents erosion and wear of the metal wall of the key-plate recess 18.
An [0028] end cap 15 is provided to close off the direction changing cavity 16. The end cap 15 is removable to permit access to the direction changing cavity 16 for installing and removing the direction changing cavity liner 60 and the key plate liner 70. The end cap 15 can be unthreaded and removed to provide access to direction changing cavity 16. The direction changing cavity liner 60 is removed by sliding it out of the direction changing cavity 16. Once the direction changing cavity liner 60 is removed, the key plate liner 70 can be removed by tilting it out of key plate recess 18 and pulling it through the directional changing cavity 16 and out of the access opening. When the direction changing cavity liner 60 and the key plate liner 70 are removed, the hex head 42 of the pressure reducer 40 is accessible for removal or installation of the pressure reducer 40.
[0029] End cap 15 has a port 13 formed therethrough to provide a connection point for a pressure gauge or other pressure sensing device. A second port 14 is formed in the body of pressure reducing valve 10 adjacent to the key-plate recess 18 to provide a connection point for a second pressure gauge or sensing device.
The [0030] upstream channel 11 is generally cylindrical and has an inlet portion characterized by a first diameter and an outlet portion 52 that is characterized by a second diameter smaller than the first diameter. The inlet portion and the outlet portion meet at an upstream channel maintenance point 12 which serves as a stop for the upstream channel liner 50. Referring now to FIG. 3, there is shown an upstream channel liner 50 in accordance with the present invention. The upstream channel liner 50 is generally cylindrical and has an inlet portion and an outlet portion. The inlet portion has a diameter that is generally commensurate with the inside diameter of the inlet portion of upstream channel 11 and the outlet portion has an outside diameter that is generally commensurate with the inside diameter of the outlet portion of upstream channel 11. That arrangement provides a shoulder stop 53 on the exterior of the upstream channel liner 50 which abuts the upstream channel maintenance point 12 when inner end 52 is inserted into the upstream channel 11. The abutment of the shoulder stop 53 with the maintenance point 12 prevents the liner from shifting toward the direction changing cavity 16 when oil is flowing. The upstream channel liner 50 has an internal channel that extends from an opening 51 to the outlet portion 52. The opening is preferably flared to lessen flow turbulence as the oil enters the upstream channel liner 50. In the embodiment shown in FIG. 3, the internal channel tapers to a smaller cross section as it traverses the outlet portion 52. The tapered channel portion 54 relieves some of the pressure and turbulent flow of the oil as it flows through the upstream channel 11. The upstream channel liner 50 is formed of a ceramic material.
Shown in FIG. 4 is an alternative embodiment of the [0031] upstream channel liner 50. In the embodiment shown in FIG. 4, the internal channel 55 has a uniform cross section to maximize flow.
Referring now to FIGS. 2, 5A, and [0032] 5B, the direction changing cavity liner 60 is disposed within the directional changing cavity 16 of pressure reducing valve 10. The directional changing cavity liner 60 is formed of a ceramic material. The liner 60 is generally cylindrical and has an outside diameter that is dimensioned to provide a snug fit between the outer surface of the liner 60 and the inner surface of the cavity 16. A recess 64 is formed in one end of the liner 60. The recess is dimensioned to provide a space around the head 42 and shoulder 43 of the pressure reducer 40 when it is fully threaded into the downstream channel 17. A central through-hole 61 extends along the length of the direction changing cavity liner 60 to provide a path between the recess 64 and the port 13 for pressure indication. The directional changing cavity liner 60 has a key-way 62 formed thereon which extends longitudinally partially along the exterior of direction changing cavity liner 60. The directional changing cavity liner 60 also has a key plate thru-hole 63 formed therein between the recess 64 and the key-way 62 to provide fluid communication between recess 64 and port 14.
Referring now to FIGS. 2, 6A, and [0033] 6B, the key plate liner 70 is positioned within the key plate recess 18 of reducing valve 10. Key plate liner 70 contains a key plate thru-hole 71 which aligns with the key plate port 14 and the key plate thru-hole 63 to provide fluid communication between the recess 64 and the key plate port 14. Key plate liner 70 also has a key 72 formed thereon which is dimensioned to mate with the key-way 62 in liner 60 to ensure proper alignment of the key plate liner 70 and the cavity liner 60. The key plate liner 70 is formed of a ceramic material.
Referring now to FIGS. 2 and 7, the [0034] downstream channel liner 80 is disposed within the downstream channel 17. The downstream channel 80 is generally cylindrical in shape and has an outside diameter that is dimensioned to provide a tight fit with the downstream channel 17. Because of that arrangement, the downstream liner 80 prevents the oil from backwashing between the liner and the interior wall of downstream channel 17. The downstream channel 80 extends less than the full length of the downstream channel 17 so that an attachment region is provided where the pressure reducer 40 can be attached to the body of the pressure reducing valve 10. In the embodiment shown, the pressure reducer 40 is attached by threading it into the downstream channel 17. The downstream channel liner 80 is formed of a ceramic material.
As shown in FIG. 2, [0035] pressure reducer 40 is situated in downstream channel 17 and projects into direction changing cavity 16. Referring now to FIG. 8, there is shown a preferred arrangement for the pressure reducer 40. The pressure reducer 40 is generally cylindrical and has an outside diameter that is substantially commensurate with the inside diameter of downstream liner 80. A series of screw threads 44 are formed on the outer surface adjacent the shoulder 43. The pressure reducer 40 is formed of a ceramic material. A central channel 45 extends longitudinally through the body of the pressure reducer 40 from entry port 41 to an outlet port 49. The central channel 45 flares to a larger inside diameter to provide a pressure reducing effect as the oil flows from entry port 41 through the central channel. When the pressure reducer 40 is threaded into the downstream channel 17, sealing shoulder 43 presses against a washer or gasket to provide a fluid-tight seal against the abrasive flow of oil and sand from direction changing cavity 16. The washer or gasket is preferably formed of Buena-N gasket material or an equivalent thereof.
FIG. 9 shows a second alternative embodiment of [0036] pressure reducer 40. The embodiment shown in FIG. 9 has a generally cylindrical body including a head portion 92 with a plurality of entry holes 46 formed therein to provide an inlet for the oil. The pressure reducer 40 has a central channel 48 formed longitudinally therethrough. The central channel 48 has a substantially uniform cross section along its length and extends from the head portion 92 to an outlet port 94 in the other end of the pressure reducer 40. The entry holes 46 are in fluid communication with the central channel 48. A hexagonal shoulder 47 is formed about the circumference of the pressure reducer 40 adjacent the head portion 92. The hexagonal shoulder 47 performs the functions of the hex head 42 and shoulder 43 of the embodiment shown in FIG. 8.
Referring back to FIG. 2, upstream [0037] cylindrical liner 50 and downstream cylindrical liner 80 are removed by un-bolting flange connections at both ends of reducing valve 10, removing reducing valve 10 from the process piping, and sliding upstream cylindrical liner 50 and downstream cylindrical liner 80 out of upstream canal 11 and downstream canal 17, respectively. The liners are installed by reversing this process.
Referring now to FIG. 10, there is shown a spool assembly including a [0038] first spool adapter 20 and second spool adapter 30. First spool adapter 20 has a steel body with a central longitudinal channel 21 having a substantially uniform cross section along the length thereof. A ceramic channel liner 22 having a substantially uniform outside diameter 23 that is dimensioned to provide a light press fit in the central channel 21 of first spool adapter 20. The ceramic channel liner 22 extends substantially the entire length of the central channel 21. Channel liner 22 has a flow channel 24 that extends the length of the channel liner 22. The cross section of the flow channel 24 gradually widens in the direction of the oil flow from the inlet of the spool adapter 20 adjacent the pressure reducing valve 10 to its outlet adjacent the second spool adapter 30. The gradual widening or flaring of the flow channel 24 minimizes turbulent, abrasive, flow that would aggravate the wear and erosion caused by the flow of oil and sand therethrough, thus increasing the useful life of the spool adapter 20.
The [0039] second spool adapter 30 has a steel body with a central longitudinal channel 31. A ceramic channel liner 32 has a substantially uniform outside diameter 33 that is dimensioned to provide a light press fit in the central channel 31 of second spool adapter 30. Ceramic channel liner 32 has a flow channel 36 that extends from the inlet adjacent the first spool adapter to the outlet adjacent the downstream process piping (not shown). The central channel 36 has a flared portion 34 and a uniform cross section portion 35. The flared portion 34 extends from the inlet along part of the length of ceramic liner 32. The degree of flaring is such as to continue the flaring of the flow channel 24 of the first spool adapter 20. The inside diameter of the uniform cross section portion 35 is dimensioned to be commensurate with the inside diameter of the downstream process piping.
As described above, the [0040] pressure reducer 40, upstream channel liner 50, direction changing cavity liner 60, key plate liner 70, downstream channel liner 80, and the central longitudinal channel liners 22 and 32, are all formed of a ceramic material. The ceramic material is selected from the class of technical ceramics, particularly technical ceramic materials that exhibit superior wear resistance and strength. Among the preferred ceramic materials are aluminum oxide (alumina), chromium oxide, high alumina, titanium oxide (titania), zirconium oxide (zirconia) ceramics, including fully and partially stabilized zirconia, and combinations of such metal oxides. It is believed that just about any type of metal-oxide ceramic will provide acceptable properties. Excellent results have been achieved using partially stabilized zirconia (PSZ) for making the aforesaid components. Particular species of PSZ that are believed to be useful for the aforesaid components include Mg-PSZ and vitreous PSZ. Silicon nitride, quartz, and silicon carbide ceramics are also expected to be useful in such components.
Referring now to FIG. 11, there is shown an alternative embodiment of a pressure reducing valve according to the present invention. The [0041] pressure reducing valve 110 has a metallic body 120 that includes an upstream channel 111 and a downstream channel 117. Upstream channel 111 has an inlet portion 115 and an outlet portion 116 which meet at a maintenance point 112. An upstream channel liner 150 is disposed in the upstream channel 111, and likewise, a downstream channel liner 180 is disposed in the downstream channel 117. Channel liners 150 and 180, among other things, prevent erosion of the inner walls of the channels 111 and 117, respectively, by the oil/sand mixture flowing through pressure reducing valve 110, from the oil well. A gauge port 114 is formed in the metallic body 120 to provide a connection point for a pressure gauge, or other sensing device. Gauge port 114 has one end in communication with downstream channel 117.
[0042] Upstream channel liner 150 is slidably disposed within upstream channel 111. As shown in FIG. 12, the upstream channel liner 150 is generally cylindrical and has an inlet portion 151, which is characterized by a first diameter, and an outlet portion 152, which is characterized by a second diameter smaller than the first diameter. Inlet portion 151 has an outside diameter that is generally commensurate with the inside diameter of the inlet portion 115 of upstream channel 111 and the outlet portion 152 has an outside diameter that is essentially commensurate with the inside diameter of the outlet portion 116 of upstream channel 111. That arrangement provides a shoulder 153 which abuts the maintenance point 112 when channel liner 150 is inserted into upstream channel 111. The abutment of shoulder 153 with maintenance point 112 prevents the liner 150 from shifting toward downstream liner 180 when oil is flowing through reducing valve 110. The upstream channel liner 150 has an internal channel 154 that extends from the inlet portion 151 to the outlet portion 152. Channel 154 is preferably tapered to lessen flow turbulence as oil flows through upstream channel liner 150. In the embodiment shown in FIG. 12, the internal channel tapers to a smaller cross section as it traverses to the outlet portion 152. The upstream channel liner 150 is preferably formed of a ceramic material as described above.
[0043] Downstream channel liner 180 is slidably disposed in the downstream channel 117, as shown in FIG. 11. Referring now to FIG. 13, downstream channel liner 180 is generally cylindrical and has an inlet end 181 and an outlet end 182. Downstream channel liner 180 has a through-hole 183, which is oriented and positioned to align with gauge port 114. Through-hole 183 extends radially through channel liner 180 and is in fluid communication with internal channel 184 of the channel liner 180. A recess 185 is formed in liner 180; at the inlet end 181. Recess 185 is generally cylindrical in shape and is dimensioned and positioned to receive the inner end 155 of upstream liner 150. Channel 184 extends between the inlet end 181 and the outlet end 182 of liner 180. Channel 184 is flared near outlet end 182 to minimize turbulent flow that would aggravate the wear and erosion caused by the flow of oil and sand. Downstream channel liner 180 is preferably formed of a ceramic material as described above.
In connection with this embodiment of the invention, a pressure reducing valve has been described which has only upstream and downstream ceramic liners. These ceramic liners are slidably disposed in the fluid flow channels of the pressure reducing valve assembly to protect the metallic walls of the channels from erosive wear. Furthermore, the pressure reducing valve of this embodiment has fewer components than the first-described embodiment and thus, is easier to assemble and disassemble. The upstream liner interconnects with the downstream liner, so as to keep them both securely in place. [0044]
Referring now to FIGS. [0045] 14-16, a third embodiment of the pressure reducing assembly is shown and designated generally as 220. The pressure reducing assembly 220 has a valve body 222 and an adjustable valve assembly 240 operable to change the pressure of oil flowing in the line. The valve assembly 240 may be adjusted to vary the pressure in the oil line during operation, and without shutting off equipment or opening the valve body. The pressure reducing assembly 220 has an upstream channel 224 and a downstream channel 226. A flow direction changing cavity 228 connects the upstream channel 224 with the downstream channel 226. The flow direction changing cavity 228 may have a variety of shapes, such a cylindrical shape. As in the previous embodiments, the pressure reducing assembly 220 has internal liners and components formed of a ceramic material to provide resistance to wear from sand and other debris in oil.
As shown in FIG. 14, the [0046] body 222 may be formed of any durable material such as steel. The upstream channel 224 is fluidly connected to the direction changing cavity 228 by a circular orifice 234. Oil enters the body 222 through the upstream channel 224, passes through the orifice 234, and enters the direction changing cavity 228 before exiting through the downstream channel 226. An upstream channel liner 225 formed of ceramic material is situated in the upstream channel 224. Similarly, a downstream channel liner 227 formed of ceramic material is positioned in the downstream channel 226. The upstream and downstream channel liners 225, 227 provide barriers that prevent erosion of the inner walls of the upstream and downstream channels 224, 226 by the oil/sand mixture flowing from the oil well. In addition, the upstream and downstream channel liners 225, 227 are configured to form a tight fit in the upstream and downstream channels 224, 226 respectively. In this way, the liners 225, 227 prevent backwashing of oil and sand between the liners and the channel walls.
The [0047] upstream channel 224 is generally cylindrical and has an inlet portion characterized by a first diameter and an outlet portion that is characterized by a second diameter smaller than the first diameter. The inlet portion and the outlet portion meet at an upstream channel maintenance point 229 which serves as a stop for the upstream channel liner 225. The upstream channel liner 225 is generally cylindrical and has an inlet portion and an outlet portion. The inlet portion of upstream liner 225 has an outside diameter that is generally commensurate with the diameter of the inlet portion of upstream channel 224, and the outlet portion of the upstream liner has an outside diameter that is generally commensurate with the diameter of the outlet portion of the upstream channel. That arrangement provides a shoulder stop 231 on the exterior of the upstream channel liner 225 which abuts the upstream channel maintenance point 229 when upstream channel liner is inserted into the upstream channel 224. The abutment of the shoulder stop 231 with the maintenance point 229 prevents the upstream channel liner from shifting toward the direction changing cavity 228 when oil is flowing. As in the previous embodiments, the upstream channel liner 225 preferably has a flared opening to lessen flow turbulence as the oil enters the upstream channel liner. In addition, the upstream channel liner 225 may have a tapered bore to relieve some of the pressure and turbulent flow of the oil as it flows through the liner.
The [0048] downstream channel 226 is generally cylindrical and has an inlet portion characterized by a first diameter and an outlet portion that is characterized by a second diameter smaller than the first diameter. The inlet portion and the outlet portion meet at an annular shoulder or transition 232 which serves as a stop for the downstream channel liner 227. The downstream channel liner 227 is generally cylindrical and has an inlet portion and an outlet portion. The inlet portion of downstream liner 227 has an outside diameter that is generally commensurate with the diameter of the inlet portion of the downstream channel 226, and the outlet portion of the downstream liner has an outside diameter that is generally commensurate with the diameter of the outlet portion of the downstream channel. That arrangement provides a shoulder stop 233 on the exterior of the downstream channel liner 227 which abuts the transition 232 when the downstream channel liner is inserted into the downstream channel 226. The abutment of the shoulder stop 233 with the transition 232 prevents the downstream channel liner 227 from shifting toward downstream components when oil is flowing.
The [0049] valve assembly 240 is configured to form a flow constriction at the orifice 234 between the upstream channel 224 and the direction changing cavity 228. In this regard, the valve assembly functions to limit oil flow and reduce pressure in the oil line. The valve assembly may have a variety of component configurations to perform this function. A preferred configuration will be described with reference to FIGS. 15 and 16. The valve assembly 240 has a disk 242 positioned in the direction changing cavity 228. The valve disk 242 has a generally cylindrical base 244 and a narrow cylindrical stem 246 that is joined coaxially to the base. During operation of the pressure reducing assembly 220, the valve disk 242 is positioned in direct contact with oil that flows through the direction changing cavity 228. Therefore, the valve disk 242 is formed of a ceramic material that is resistant to wear and abrasion caused by sand and other debris present in oil.
The [0050] valve disk 242 is rotatable in the direction changing cavity 228 and is formed to provide control of the pressure in the oil line by adjusting the volumetric flow of the oil from the upstream channel 224 into the direction changing cavity 228. To that end, the base 244 of valve disk 242 has a sidewall 245. When the valve disk 242 is positioned in the direction changing cavity 228, the sidewall 245 obstructs the orifice 234 between the upstream channel 224 and direction changing cavity 228, as shown in FIG. 14. Referring now to FIG. 16, the base 244 has a bottom end 248 that comprises a helical surface 247 and an adjacent planar surface 249. The helical surface 247 begins at the planar surface section 249 on the bottom end 248 and terminates at a preselected distance from the plane of the planar surface 249. In the preferred embodiment, the helical surface 247 extends through an angle of approximately 270 degrees about the longitudinal axis of the valve disk 242.
Because of the helical surface [0051] 247 formed in the bottom end 248, the height of the sidewall 245 varies around the circumference of the base 244. Thus, the height of the sidewall 245 is a maximum at an angular position where the planar surface 249 is located on bottom end 248. The height of the sidewall 245 is a minimum at the angular position where the distance between the helical surface 247 and plane of the planar surface 249 on the bottom end 248 is a maximum. When the valve disk 242 is in an angular position in which the planar section 249 aligns with the position of the orifice 234, the sidewall 245 substantially obstructs the orifice 234. In this position, the “closed position”, the valve disk 242 substantially blocks flow through the orifice 234. When the disk is in an angular position in which the minimum height portion of the sidewall 245 aligns with the orifice 234, the “full open position”, a passage is established that permits a maximum oil flow through the orifice 243.
Because the height of [0052] sidewall 245 varies around the circumference of the base 244, the volumetric flow of the oil through the orifice 243 can be varied by rotating the valve disk 242 about its longitudinal axis in the direction changing cavity. In this manner, the volumetric flow, and thus the fluid pressure, can be adjusted to a desired level.
Referring now to FIG. 16, the [0053] valve disk 242 is connected to a cylindrical coupling 250 that is attached over the stem 246. The coupling 250 has an outside diameter that is generally commensurate with the outside diameter of the base 244 on the valve disk 242. Unlike the valve disk 242, the coupling is not ordinarily exposed to oil that flows through the assembly and need not be formed of a ceramic material. Preferably, the coupling is formed of a durable corrosion resistant material such as stainless steel. The coupling 250 may be attached to the valve disk 242 in a variety of ways. In the preferred embodiment, the coupling 250 is connected to the stem 246 by a sweat and shrink fit process. The coupling 250 has a bore 254 with a diameter generally commensurate with the outside diameter of the cylindrical stem 246 on the valve disk 242. Prior to connecting the coupling 250 to the stem 246, the coupling is heated so that the diameter of the bore 254 expands. The coupling 250 is then lowered over the stem 246 so that the stem extends into the bore 254 of the coupling. The coupling 250 is then allowed to cool. As the coupling 250 cools, the bore 254 contracts around the stem 246 to secure the coupling to the valve disk 242.
The [0054] base portion 244 of the valve disk 242 has a top face with a hole 241 that extends into the body of the base, as shown in FIG. 15. A similar size hole 251 is formed in the coupling, as shown in FIG. 16. The holes 241, 251 are aligned with one another when the coupling 250 is placed over the stem portion 246 of the valve disk 242 during the sweat and shrink fit process. Prior to placing the coupling 250 over the stem 246, a pin 252 is inserted into hole 241 on base portion 244. The pin 252 is configured to project outwardly from hole 241. The portion of the pin 252 that projects from hole 241 is configured to extend into hole 251 in coupling 250 when the coupling is lowered over the valve stem 246 during the sweat and shrink fit process. Once the coupling 250 and valve disk 242 are joined, the pin 252 substantially prevents the valve disk from rotating relative to the coupling. As such, the valve disk 242 and coupling 250 are rotatable as a unit.
A [0055] cylindrical liner 260 formed of a ceramic material protects the inner walls of the flow direction changing cavity 228 from abrasion caused by sand and debris in the oil. The cylindrical liner 260 has a bore 266 with a diameter generally commensurate with the outside diameter of the coupling 250 and the diameter of the base portion 244 of the valve disk 242. As such, the liner 260 is adapted to fit over the coupling 250 and valve disk 242 in the direction changing cavity 228. The liner 260 has a bottom edge with an notch 262 formed therein. The notch 262 is aligned with the orifice 234 when the liner 260 is inserted in the direction changing cavity. Once aligned with the orifice 234, the notch 262 permits fluid communication from the orifice 234 into the direction changing cavity 228.
If the [0056] assembly 220 requires servicing or removal from the oil line, the oil well is shut down and external isolation valves are closed around the valve body 222. Oil is drained from the assembly 220. To open the assembly 220 or remove the assembly from the oil line, the pressure in the assembly must be equalized with ambient pressure outside of the assembly. Referring now to FIG. 14, the valve body 222 preferably includes a side port 238 formed by a pair of coaxial bores that align with one another and extend through the valve body and liner 260, respectively. The side port 238 is adapted to receive a bleed screw or plug that is inserted into the valve body through the side port 238 of the assembly 220. The bleed screw or plug is removable from the side port 238 to relieve internal pressure in the assembly 220 and facilitate opening of the valve body or removal of the assembly 220 from the line.
As described above, the [0057] downstream channel liner 227 is substantially prevented from shifting toward downstream components by the abutment between the shoulder stop 233 and the transition 232. The shoulder stop 233 and transition 232 maintain the downstream liner 227 in an axially fixed position in the downstream channel 226. The downstream liner 227 has a top end that functions as a seat 235 for the valve disk 242. The seat 235 abuts the bottom end 248 of the valve disk 242 to limit downstream displacement of the valve disk. The top end of the downstream liner 227 also forms a circumferential groove 236. The groove 236 is adapted to receive and abut the bottom edge of the liner 260. As such, downstream liner 227 substantially prevents downstream displacement of the valve disk 242 and liner 260 in the direction changing cavity 228.
A removable bonnet collar or [0058] end cap 280 is provided to allow access to the interior of the valve assembly 220. The end cap 280 is configured to close and seal the direction changing cavity 228 so as to prevent the release of oil flowing from the assembly 220. The cap 280 may be secured to the valve body 222 using fasteners, threads, clamps, or other connecting means. In the embodiment shown in FIG. 15, the cap 280 has a plurality of holes 282 that can be aligned with corresponding threaded holes 284 extending into the valve body 222. When the cap 280 is placed over the valve body 222 and the holes 282, 284 are aligned, the cap is secured to the valve body by a plurality of bolts 286 that are inserted into the holes 282, 284. The bolts 286 have threads that mate with the threads in the hole 284.
Referring now to FIG. 14, a [0059] retainer 270 is provided in the end cap 280 and extends partially into the direction changing cavity 228. The end cap 280 has a cavity that conforms to the exterior shape of the retainer 270. As such, the end cap 280 tightly engages with the retainer when the end cap is secured to the valve body 222, thereby securing the retainer in place. The coupling 250 and cavity liner 260 each have top edges that abut the retainer 270. More specifically, the retainer 270 has a narrow rim 272 that extends into the direction changing cavity 228 to engage the coupling 250 and cavity liner 260. When the end cap 280 is positioned over the retainer 270 and secured to valve body 222, the retainer substantially prevents axial displacement of the coupling 250 and liner 260 toward the end cap during periods when the coupling and liner are subject to high operating pressures. The rim 272 also forms a first fluid tight seal that prevents oil from seeping out of the direction changing cavity 228.
The [0060] retainer 270 also has a circumferential flange 274 that abuts the top of the valve body 222. The flange 274 forms a second fluid tight seal that prevents oil from seeping out of the valve body 222. A bore 276 extends through the retainer 270 in coaxial alignment with the longitudinal axis of the retainer and direction changing cavity 228, a shown in FIG. 15.
A [0061] shaft 290 having an upper end 292 and a lower end 294 is connected to the coupling 250. The shaft 290 connects the valve assembly 240 to an external mechanism that is operable to rotate the collar 200 and valve disk 242. The shaft 290 extends through the retainer 270 and valve body 222 and projects into the valve assembly 240. The lower end 294 of shaft 290 has a diameter generally commensurate with the diameter of the bore 254 in coupling 250. The lower end 294 is inserted into the bore 254 to connect the shaft to the coupling 250. The coupling 250 and lower end 294 of the shaft 290 are both metallic and may be connected by a weld or other mechanical connection of comparable strength. Once connected to the coupling 250, torque may be applied to the shaft 290 to rotate the coupling and valve disk 242. The bores 266, 276 of the cavity liner 260 and retainer 270 are dimensioned to provide adequate clearance so that the shaft can rotate freely without bearing or rubbing against surfaces inside the cavity liner 260 and retainer 270.
The [0062] upper end 292 of shaft 290 extends outside the cap 280 and is adapted for attachment to a lever bar, wheel handle, or other external mechanism (not shown) that can apply torque to the shaft. The upper end may have a variety of configurations to connect with the external mechanism. In FIG. 15, the upper end 292 has a square-shaped transverse cross-section that may be inserted into the hub of a wheel handle or coupled to the drive shaft of drive mechanism. The pressure reducing assembly 220 may be used with a variety of operative devices, including but not limited to lever or wheel handles for manual operation, or pneumatic or motor driven actuators with or without gear reduction.
Preferably, the [0063] pressure reducing assembly 220 has a stop mechanism that prevents the valve disk 242 from being rotated from the closed position directly into the full open position, and vice versa. In this way, the range of rotation of the valve disk 242 is limited so that the assembly 220 is not subject to a rapid pressure change resulting from rotation of the disk from the closed position directly to or from the full open position. The stop mechanism may be incorporated into the external operation mechanism.
The [0064] valve disk 242 is formed of any technical ceramic material, including aluminum oxide (alumina), chromium oxide, high alumina, titanium oxide (titania), zirconium oxide (zirconia) ceramics, including fully and partially stabilized zirconia, and combinations of such metal oxides. By using a ceramic material, the valve disk 242 can be formed to very precise dimensions to provide optimum flow characteristics. The ceramic material is also more resistant to abrasion and wear than metallic materials. As a result, the ceramic surfaces are less prone to abrasion and channeling, which can adversely affect the flow properties of the recess. Valve disks formed of foundry forged steel or other metal alloys would not provide the same performance and are not as desirable as the ceramic material. In particular, prolonged abrasion on metal surfaces around the recess can lead to gross failure of the valve disk in a relatively short period of time. Therefore, the ceramic components of the present invention provide precise pressure control and offer a longer service life than components made of metal alloys.
The [0065] valve assembly 240 provides an advantage over other metered pressure reducers. In most of such devices, the pressure reducer is threaded into the downstream channel wall and rotated within the flow channel to move the reducer up and down. Threads can become galled and clogged by debris, and must be lubricated with grease to minimize binding. The valve disk 242 in the present embodiment slidably engages the side wall of the direction changing cavity 228 and is limited to rotational displacement. The axial position of the valve disk 242 relative to the direction changing cavity 228 is fixed by the seat 235 on the downstream channel liner 227 and the rim 272 on the retainer 270. With this arrangement, the valve disk 242 does not move longitudinally within the cavity 228. Frictional resistance between the side wall of the direction changing cavity 228 and the valve disk 242 does not significantly impede rotation of the disk. Therefore, there is no requirement for lubrication.
It can be seen from the foregoing description and the accompanying drawings that the present invention provides a novel means for extending the operating life of high pressure oil well components and for maintaining desired operating pressures by substantially reducing the rate of abrasive wear to components in a pressure reducing assembly for a high pressure oil well head. Although the invention has been described with reference to specific components and assemblies thereof, including a ceramic pressure reducer, a ceramic-lined reducing valve, ceramic-lined spool pipe adapters, and ceramic disks, it is contemplated that any metal component in such a pressure reducing assembly that is subject to erosive wear caused by the flow of an oil/sand mixture under very high pressure can be formed from or lined with a ceramic material to substantially reduce the rate of wear and erosion. A distinct advantage of the present invention is that a high pressure oil well, incorporating ceramic components in accordance with this invention, can be operated, at the desired high well pressures while keeping the sand content low. The desired high pressures can be maintained over a much longer period of time than obtainable with known components because component deterioration is minimized. In addition, the use of ceramic material has the unexpected benefit of providing intricate flow channel design that is not affected by abrasive elements in oil. Lost oil production resulting from well down-time, during spent component replacement, is drastically reduced, because of the increased wear resistance and more efficient flow design of the ceramic components. [0066]
It will be recognized by those skilled in the art that changes or modifications may be made to the above described embodiments without departing from the broad, inventive concepts of the invention. The terms and expressions which have been employed above are used as terms of description and not of limitation. There is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. For example, the [0067] valve assembly 240 described in the third embodiment was described as having a disk 242 with a helical bottom end surface 247 and a sidewall 245 that varies in height. The disk 242 forms a flow passage when sections of the sidewall having a reduced height are aligned with the upstream channel. The present invention may also be used with an oval-shaped disk or body that rotates in a cylindrical chamber. The oval-shaped disk engages the chamber wall on a portion of its perimeter, creating gaps that may be aligned with the upstream channel when the oval-shaped disk is rotated to permit passage of oil through the chamber. Alternatively, the present invention may be used with a disk having a uniform height that features a conduit extending through the interior of the disk. In this embodiment, the conduit enters through the sidewall of the disk, passes through the interior of the disk and exits through the bottom edge of the disk. The conduit forms an opening through the sidewall of the disk that can be partially or completely aligned with the upstream channel to permit controlled flow of oil through the disk and chamber, said opening also being rotatable out of alignment with the upstream channel to prevent passage of oil through the chamber. Accordingly, the invention incorporates many variations that fall within the scope of the following claims.

Claims

I claim:

1. A pressure reducing assembly for a high pressure oil well, comprising:

A. an upstream channel;

B. a hollow housing having a port that fluidly connects the housing with the upstream channel;

C. a disk disposed in the housing and rotatable between a first orientation in which the port is substantially obstructed by the disk and a second orientation in which the port is substantially unobstructed by the disk; and

D. a downstream channel,

wherein the disk has a side wall that covers the port when the disk is rotated to the first orientation to substantially prevent fluid in the upstream channel from entering the housing.

2. The pressure reducing assembly of claim 1, wherein the disk is mounted on a shaft that extends outside the housing and is operable to rotate the disk between the first orientation and the second orientation.

3. The pressure reducing assembly of claim 1, wherein the disk is formed of a ceramic material.

4. The pressure reducing assembly of claim 3, wherein the disk is formed of a technical ceramic material selected from the group consisting of alumina, chromium oxide, titania, zirconia, partially stabilized zirconia, silicon nitride, silicon carbide, and combinations thereof.

5. The pressure reducing assembly of claim 1, wherein the disk comprises a cylindrical body having a radially relieved recess configured to align with the port and permit the flow of fluid from the upstream channel into the housing when the disk is rotated from the first orientation to the second orientation.

6. A pressure reducing assembly for a high pressure oil well, comprising:

A. a hollow body having an upstream channel and a downstream channel;

B. a flow channel between the upstream channel and the downstream channel, said flow channel having a longitudinal axis; and

C. a disk having a bottom edge and disposed in the flow channel, said disk being rotatable in a fixed position on the longitudinal axis of the flow channel to alter the pressure of fluid passing through the flow channel,

wherein the disk comprises a recess along the bottom edge of the disk that aligns with the upstream channel, said recess having a transverse cross-sectional area smaller that the cross-sectional area of the upstream channel so as to form a flow constriction that reduces the pressure of fluid as it passes through the flow chamber.

7. The pressure reducing assembly of claim 6, wherein the recess has a cross-sectional area that increases gradually to form a generally helical bottom edge, such that rotation of the disk changes the size of the flow constriction formed by the alignment between the upstream channel and the recess.

8. The pressure reducing assembly of claim 6, wherein the disk is formed of a ceramic material.

9. The pressure reducing assembly of claim 8, wherein the disk is formed of a technical ceramic material selected from the group consisting of alumina, chromium oxide, titania, zirconia, partially stabilized zirconia, silicon nitride, silicon carbide, and combinations thereof.

10. A pressure reducing assembly for a high pressure oil well, comprising:

a housing formed of a metallic material, said housing including an upstream channel, a downstream channel, and a pressure reducing chamber disposed between said upstream and downstream channels;

an inlet port for permitting fluid communication between said upstream channel and said pressure reducing chamber;

an outlet port for permitting fluid communication between said pressure reducing chamber and said downstream channel;

a disk disposed in said pressure reducing chamber, said disk having a sidewall that abuts said inlet port and a bottom end that abuts said outlet port, said disk being formed such that the height of the sidewall varies from a maximum height to a minimum height around the circumference of said disk; and

means for rotating said disk within the pressure reducing chamber such that the height of the sidewall facing said inlet port can be varied, whereby oil flow through the pressure reducing assembly can be throttled.

11. The pressure reducing assembly of claim 10 wherein the bottom end of said disk comprises a helical surface.

12. The pressure reducing assembly of claim 11 wherein the bottom end of said disk further comprises a planar surface disposed at an angular position where the height of the sidewall is a maximum.

13. The pressure reducing assembly of claim 12 wherein said helical surface begins at said planar surface and terminates at a preselected distance from the plane of said planar surface.

14. The pressure reducing assembly of claim 10, wherein the disk is formed of a ceramic material.

15. The pressure reducing assembly of claim 14, wherein the disk is formed of a technical ceramic material selected from the group consisting of alumina, chromium oxide, titania, zirconia, partially stabilized zirconia, silicon nitride, silicon carbide, and combinations thereof.

16. A pressure reducing assembly for a high pressure oil well, comprising:

an inlet port between said upstream channel and said pressure reducing chamber for permitting fluid communication between said upstream channel and said pressure reducing chamber;

an outlet port between said pressure reducing chamber and said downstream channel for permitting fluid communication between said pressure reducing chamber and said downstream channel;

a disk disposed in said pressure reducing chamber, said disk having a sidewall and a bottom end, said disk having a passageway formed therein between the sidewall and the bottom end, said passageway having a first aperture in the sidewall and a second aperture in the bottom end;

means for rotating said disk within the pressure reducing chamber such that the first aperture can be moved into or out of alignment with said inlet port, whereby oil flow through the pressure reducing assembly can be throttled.

17. The pressure reducing assembly of claim 16 wherein the bottom end of said disk comprises a helical surface.

18. The pressure reducing assembly of claim 17 wherein the bottom-end of said disk further comprises a planar surface disposed at an angular position where the height of the sidewall is a maximum.

19. The pressure reducing assembly of claim 18 wherein said helical surface begins at said planar surface and terminates at a preselected distance from the plane of said planar surface.

20. The pressure reducing assembly of claim 16, wherein the disk is formed of a ceramic material.

21. The pressure reducing assembly of claim 20, wherein the disk is formed of a technical ceramic material selected from the group consisting of alumina, chromium oxide, titania, zirconia, partially stabilized zirconia, silicon nitride, silicon carbide, and combinations thereof.