Patent Application
20130255934
This invention relates, in general, to equipment utilized in conjunction with operations performed in subterranean wells and, in particular, to a downhole circulating valve having a metal-to-metal seal in its non-circulating configuration and method for operating the downhole circulating valve between circulating and non-circulating configurations.
Without limiting the scope of the present invention, its background will be described with reference to operations performed in a subterranean well that traverses a fluid-bearing subterranean formation, as an example. Subterranean wellbores are generally filled with fluids that extend from the lower end of the wellbore to the earth's surface. During drilling and completions operations, a weighted column of fluid is usually present adjacent to each of the fluid-bearing formations intersected by the wellbore, so that the column of fluid may exert hydrostatic pressure on the formations sufficient to prevent uncontrolled flow of fluid from the formations into the wellbore, which uncontrolled flow of fluid could result in a blowout.
In order to transport fluid, tools, instruments and the like within the wellbore, it is common practice to utilize a tubular string, such as drill pipe or production tubing, to which tools and instruments may be attached and within which fluid may be flowed and tools and instruments may be conveyed. When such a tubular string is disposed within the wellbore, the fluid column within the wellbore may be effectively divided into multiple portions. For example, a first fluid column may be contained in an annulus defined by the area separating the outside surface of the tubular string from the inside surface of the wellbore or casing string. At the same time, a second fluid column may be contained within the interior of the tubular string. In such a configuration, tools, instruments and the like may be transported within the wellbore attached to or within the tubular string without disturbing the relationship between the fluid column in the annulus and the fluid-bearing formations intersected by the wellbore.
After completing the well, it is typically desirable to remove the weighted column of fluid from both the interior of the tubular string, if present, and the annulus above the uppermost packer. This may be achieved through the use of a circulating valve disposed within in the tubular string, which has a primary purpose of selectively permitting fluid flow between the interior of the tubular string and the annulus. For example, when it is desired to remove the weighted column of fluid from the annulus, a lighter fluid may be pumped from the earth's surface down through the tubular string and radially outwardly from the tubular string through the circulating valve into the annulus and then back to the earth's surface up through the annulus. Typically, such tubing conveyed circulating valves have a sliding sleeve that may be longitudinally shifted between circulating and non-circulating positions using wireline or slickline techniques. In the non-circulating position, conventional circulating valves typically utilize resilient materials such as elastomers for sealing between movable metal parts to prevent fluid communication between the interior of the tubular string and the annulus.
It has been found, however, that resilient sealing materials may deteriorate due to the harsh chemical, physical and thermal environment downhole. When such deterioration occurs, the seals may fail to prevent fluid communication between the interior of the tubular string and the annulus when a conventional circulating valve is in its non-circulating configuration. Accordingly, a need has arisen for an improved circulating valve that is operable to selectively permit fluid flow between the interior of the tubular string and the annulus. In addition, a need has arisen for such an improved circulating valve that does not rely on resilient sealing materials to prevent fluid communication between the interior of the tubular string and the annulus when the circulating valve is in its non-circulating configuration.
The present invention disclosed herein comprises an improved circulating valve that is operable to selectively permit fluid flow between the interior of a tubular string and the annulus between the tubular string and the wellbore. In addition, the improved circulating valve of the present invention does not rely on resilient sealing materials to prevent fluid communication between the interior of the tubular string and the annulus when the circulating valve is in its non-circulating configuration but instead utilizes a metal-to-metal seal to provide a long lasting, high pressure seal.
In one aspect, the present invention is directed to a downhole circulating valve. The downhole circulating valve has a generally tubular outer housing having an axially extending internal passageway including an internal seat and at least one generally radially extending opening formed through the housing intersecting the internal seat. A valve element is rotatably disposed within the internal passageway. The valve element has an axially extending internal bore and a head portion disposed at least partially within the internal seat. The head portion includes at least one generally radially extending seal element. The valve element has a first position relative to the housing wherein the seal element is not aligned with the opening, thereby allowing fluid communication between the opening and the internal passageway. The valve element has a second position relative to the housing wherein the seal element is aligned with the opening and wherein the seal element forms a metal-to-metal seal with the internal seat, thereby preventing fluid communication between the opening and the internal passageway.
In one embodiment, the internal seat may have a spherical segment having a first radius. In this embodiment, the at least one generally radially extending opening may extend in the direction of the first radius. In some embodiments, an outer surface of the head portion may have a spherical segment having a second radius. In addition, the head portion may include at least one generally radially extending port that may extend in the direction of the second radius. The at least one generally radially extending seal element may also extend in the direction of the second radius. In certain embodiments, the first radius and the second radius may be sized to enable spherical mating of the at least one generally radially extending seal element and the internal seat. In such embodiments, the head portion may translate toward the internal seat when the valve element is operated from the first position to the second position to form the metal-to-metal seal. In one embodiment, the at least one generally radially extending seal element may include one or more seal rings each having a circular cross section.
In one embodiment, the housing may include a plurality of circumferentially distributed generally radially extending openings formed through the housing intersecting the internal seat. In this embodiment, the head portion may include a plurality of circumferentially distributed generally radially extending ports and a plurality of circumferentially distributed generally radially extending seal elements that are circumferentially offset from the ports such that in the first position, the ports are in fluid communication with the openings and, in the second position, each of the seal elements is aligned with one of the openings and forms a metal-to-metal seal with the internal seat.
In another aspect, the present invention is directed to a downhole circulating valve. The downhole circulating valve includes a generally tubular outer housing having an axially extending internal passageway including a spherical segment internal seat having a first radius and at least one generally radially extending opening formed through the housing intersecting the internal seat. A valve element is rotatably disposed within the internal passageway. The valve element has an axially extending internal bore and a head portion having an outer surface including a spherical segment with a second radius. The head portion is translatable relative to and disposed at least partially within the internal seat. The head portion includes at least one generally radially extending port and at least one generally radially extending seal element that is circumferentially offset from the port. The valve element has a first position relative to the housing wherein the port is in fluid communication with the opening and a second position relative to the housing wherein the seal element is aligned with the opening, wherein the seal element forms a metal-to-metal seal with the internal seat, wherein the first radius and the second radius are sized to enable spherical mating of the at least one generally radially extending seal element and the internal seat and wherein the head portion translates toward the internal seat when the valve element is operated from the first position to the second position.
In a further aspect, the present invention is directed to a downhole circulating system. The system includes a downhole power unit having an engagement assembly and a rotatable shaft. The system also includes a circulating valve having a generally tubular outer housing with an axially extending internal passageway including a profile, an internal seat and at least one generally radially extending opening formed through the housing intersecting the internal seat. A valve element is rotatably disposed within the internal passageway. The valve element has an axially extending internal bore with a profile and a head portion disposed at least partially within the internal seat. The head portion includes at least one generally radially extending seal element. A first portion of the engagement assembly is operably associated with the profile of the housing and a second portion of the engagement assembly is operably associated with the profile of the valve element such that when the downhole power unit is activated and the rotatable shaft is rotated, the valve element is rotatable between a first position relative to the housing wherein the seal element is not aligned with the opening and a second position relative to the housing wherein the seal element is aligned with the opening and wherein the seal element forms a metal-to-metal seal with the internal seat.
In an additional aspect, the present invention is directed to a method for operating a downhole circulating valve. The method includes providing a circulating valve having a generally tubular outer housing with an axially extending internal passageway including an internal seat and at least one generally radially extending opening formed through the housing intersecting the internal seat and a valve element rotatably disposed within the internal passageway, the valve element having an axially extending internal bore and a head portion disposed at least partially within the internal seat, the head portion including at least one seal element; running the circulating valve into a wellbore on a tubular string; running a rotating tool into the tubular string and engaging the circulating valve; and activating the rotating tool to rotate the valve element between a first position relative to the housing wherein the at least one seal element is not aligned with the at least one opening and a second position relative to the housing wherein the at least one seal element is aligned with the at least one opening and wherein the at least one seal element forms a metal-to-metal seal with the internal seat.
The method may also include running a downhole power unit having a rotatable shaft into the tubular string and engaging a profile of the housing and a profile of the valve element with the downhole power unit; activating an electric motor of the downhole power unit to impart rotary motion to the rotatable shaft; spherical mating the seal element and the internal seat by translating the head portion toward the internal seat and/or creating a metal-to-metal seal between at least one seal ring of the seal element and the internal seat.
For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.
Referring initially to
Positioned within wellbore 12 and extending from the surface is a tubing string 22. Tubing string 22 provides a conduit for formation fluids to travel from formation 20 to the surface and for injection fluids to travel from the surface to formation 20. At its lower end, tubing string 22 is coupled to a completions string that has been installed in wellbore 12 and divides the completion interval into various production intervals adjacent to formation 20. The completion string includes a plurality of sand control screens 24, each of which is positioned between a pair of annular barriers depicted as packers 26 that provides a fluid seal between the completion string and wellbore 12, thereby defining the production intervals. Tubing string 22 may include a variety of tools such as packer 28 that provides a seal between tubing string 22 and casing string 16. An annulus 30 is defined between tubing string 22 and casing string 16 above packer 28. As discussed above, during drilling and completions operations, a weighted column of fluid is usually present in the wellbore 12 to exert hydrostatic pressure on formation 20 sufficient to prevent uncontrolled flow of fluid from formation 20 into wellbore 12. To enable production, however, the weighted column of fluid must be removed from wellbore 12. In the illustrated embodiment, a circulating valve 32 is positioned within tubing string 22 above packer 28 and may be operated via a slickline or wireline deployed rotating tool depicted as downhole power unit 34. Circulating valve 32 serves the primary purpose of selectively permitting fluid flow between the interior of tubing string 22 and annulus 30.
For example, when it is desired to remove the weighted column of fluid from wellbore 12, downhole power unit 34 may be deployed via wireline 36 to engage with circulating valve 32. Typically, circulating valve 32 is initially run downhole in its non-circulating configuration to prevent fluid flow between the interior of tubing string 22 and annulus 30. Once engaged, downhole power unit 34 may be activated to operate circulating valve 32 from its non-circulating configuration to its circulating configuration. Thereafter, a lighter fluid may be pumped from the earth's surface down through tubing string 22 and radially outwardly from tubing string 22 through circulating valve 32 into annulus 30 and then back to the earth's surface up through annulus 30. After the weighted column of fluid is removed, downhole power unit 34 may be activated to operate circulating valve 32 from its circulating configuration to its non-circulating configuration. In the present invention, when circulating valve 32 is in its non-circulating configuration, one or more metal-to-metal seals prevent fluid communication between the interior of tubing string 22 and annulus 30.
Even though
Referring next to
In the illustrated embodiment, downhole power unit 102 includes a self-contained power source, eliminating the need for power to be supplied from an exterior source, such as a source at the surface, however, in other embodiments, power may be provided to downhole power unit 102 from the surface via a wired connection. A preferred power source comprises a battery assembly 108 which may include a plurality of batteries such as alkaline batteries, lithium batteries or the like. Downhole power unit 102 also has a force generating and transmitting assembly 110 that preferably includes a direct current electric motor and a gearbox. The electric motor may be of any suitable type. One example is a motor operating at 7500 revolutions per minute in unloaded condition, and operating at approximately 5000 rpm in a loaded condition, and having a horsepower rating of approximately 1/30th of a horsepower. In this implementation, the electric motor may be coupled through a gearbox, which provides approximately 5000:1 gear reduction to a sleeve assembly 112, which is in turn coupled to a rotatable shaft 114. Downhole power unit 102 may include a variety of sensors and controllers that are operable to activate and deactivate downhole power unit 102 including, but not limited to, a microcontroller, a pressure-sensitive switch, an accelerometer, a geophone or the like. Alternatively or additionally, downhole power unit 102 may be controlled from the surface via wired or wireless communications.
At its lower end, housing assembly 106 includes an engagement assembly 116. In the illustrated embodiment, engagement assembly 116 includes a set of locating keys 118, a set of anti-rotation keys 120 and a set of torque keys 122. Preferably, anti-rotation keys 120 and torque keys 122 are rotatable relative to locating keys 118. In addition, torque keys 122 are rotatable relative to anti-rotation keys 120. Torque keys 122 are operably associated with rotatable shaft 114 such that when rotatable shaft 114 is rotated, torque keys 122 are rotated therewith.
Referring additionally now to
Circulating valve 104 includes a valve element 148. In the illustrated embodiment, valve element 148 includes a lower valve section 150, an upper valve section 152 and a head portion 154. Lower valve section 150 is threadably coupled to upper housing section 132 and is secured against rotation relative to upper housing section 132 by one or more set screws 156. Upper valve section 152 is also threadably coupled to upper housing section 132 but is free to rotate relative to upper housing section 132 between two stopping points as described below. Upper valve section 152 includes a rotation profile depicted as plurality of circumferentially distributed slots 158. Head portion 154 is threadably coupled to upper valve section 152 and is secured against rotation relative to upper valve section 152 by one or more set screws 160. As such, upper valve section 152 and head portion 154 are operable to rotate together relative to upper housing section 132. In addition, due to the threaded engagement between upper valve section 152 and upper housing section 132, rotation of upper valve section 152 and head portion 154 relative to upper housing section 132 causes upper valve section 152 and head portion 154 to translate longitudinally relative to upper housing section 132. The extent of downward longitudinally travels of upper valve section 152 and head portion 154 is limited by contact between an upper valve section 152 and lower valve section 150. The extent of upward longitudinally travel of upper valve section 152 and head portion 154 is limited by contact between head portion 154 and internal seat 140, as more fully described below.
Valve element 148 has an axially extending internal bore 162. Head portion 154 has an outer surface including a spherical segment 164 with a radius R2, as best seen in
As best seen in
In the illustrated embodiment, seal elements 168 include a pair of concentric seal rings 170, 172, each having a circular cross section. Preferably, seal rings 170, 172 radially extend from head portion 154 in the direction of radius R2. As such, the outer surfaces of seal rings 170, 172 lie in a spherical segment that has a radius that enables spherical mating between the outer surfaces of seal rings 170, 172 and internal seat 140 when circulating valve 104 is in its non-circulating configuration.
In operation, downhole power unit 102 is adapted to cooperate with circulating valve 104 to enable and disable fluid circulation therethrough. Specifically, after circulating valve 104 has been run downhole as part of a tubing string and it is desired to circulate fluid between the interior of the tubing string and the annulus surrounding the tubing string, downhole power unit 102 is run downhole on a suitable conveyance such as a wireline. Upon reaching the desired depth downhole, downhole power unit 102 engages circulating valve 104. Specifically, engagement assembly 116 interacts with circulating valve 104. First, locating keys 118 engage locating profiles 146 of lower housing section 134. At this point, anti-rotation keys 120 should be axially aligned with anti-rotation profile 144 and torque keys 122 should be axially aligned with rotation profile 158. Slight rotation of rotatable shaft 114 may now be required to engage anti-rotation keys 120 with anti-rotation profile 144 and torque keys 122 with rotation profile 158, as best seen in
For example, to operate circulating valve 104 from the non-circulating configuration (
While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/US2012/031956 | Apr 2012 | US | national |
This application claims the benefit under 35 U.S.C. §119 of the filing date of International Application No. PCT/US2012/031956, filed Apr. 3, 2012. The entire disclosure of this prior application is incorporated herein by this reference.
