Patent Application
20160319621
The present invention relates to the field of couplers, and more particularly, to radio frequency and fluid couplers for subterranean assemblies.
Energy consumption worldwide is generally increasing, and conventional hydrocarbon resources are being consumed. In an attempt to meet demand, the exploitation of unconventional resources may be desired. For example, highly viscous hydrocarbon resources, such as heavy oils, may be trapped in tar sands where their viscous nature does not permit conventional oil well production. Estimates are that trillions of barrels of oil reserves may be found in such tar sand formations.
To further increase hydrocarbon resource recovery efficiency, radio frequency (RF) energy may be used to provide heating. U.S. Patent Application Publication No. 2006/0180304 to Kasevich discloses a hydrocarbon recovery process whereby an RF antenna is positioned within a borehole. RF energy is supplied to the RF antenna to heat the hydrocarbon resources. The hydrocarbon resources are recovered from the borehole.
Fluids may also be injected into the borehole to increase hydrocarbon resource recovery efficiency. For example, nitrous oxide and carbon dioxide may be injected into the borehole.
Underground RF heating generally requires a device that can supply relatively large amounts of RF power to the antenna in the subterranean formation while maintaining fluid and/or gas control both in and out of the subterranean formation. U.S. Pat. No. 7,461,693 to Considine et al. discloses a wellhead assembly or interface that allows fluid or gas and RF to be communicated from above the subterranean formation to the wellbore within the subterranean formation.
Despite the existence of such a wellhead assembly, such systems may not be relatively reliable and robust. For example, such systems may not provide desired isolation and pressure control, while maintaining desired power levels. For example, it may be particularly desirable to maintain or control the coefficient of thermal expansion (CTE) growth, the temperature of the components, e.g., antennas, chokes, etc., and overall control of the well.
A radio frequency (RF) and fluid coupler may be for a subterranean assembly that may include an RF antenna and a coaxial transmission line connected thereto. The coaxial transmission line may include an inner conductor and an outer conductor surrounding the inner conductor. The subterranean assembly may have at least one fluid passageway therein. The RF and fluid coupler may include an electrically conductive hollow body that includes electrically conductive segments connected together in end-to-end relation at respective joints to provide an outer electrical pathway to connect to the outer conductor of the coaxial transmission line. An elongate conductive member may extend within the electrically conductive hollow body to provide an inner electrical pathway to connect to the inner conductor of the coaxial transmission line. A respective dielectric pressure barrier may be between the elongate conductive member and adjacent portions of the electrically conductive hollow body adjacent each of a pair of joints to define at least one fluid chamber to connect to the at least one fluid passageway of the subterranean assembly. A fluid port may be connected to the at least one fluid chamber. Accordingly, relatively large amounts of power may be provided to the RF antenna while providing increased control, for example of CTE growth, the temperature of the components, pressure, and overall well parameters.
The RF and fluid coupler may further include at least one RF contact between adjacent ones of the plurality of electrically conductive segments at respective joints. The at least one RF contact may include at least one conductive wound spring, for example. The at least one conductive wound spring may have a generally rectangular shape, for example.
The respective joints may each include a respective slip joint. Each respective dielectric pressure barrier may include quartz fiber, for example. The RF and fluid coupler may further include at least one seal between adjacent ones of the plurality of electrically conductive segments at a respective joint.
Each of the plurality of electrically conductive segments may have an enlarged width flange at each joint and a plurality of fastener receiving passageways therein. A respective fastener may be within each fastener receiving passageway.
Each of the electrically conductive segments may include a base material and an electrically conductive material layer on the base material, for example. Each of the electrically conductive segments may include brass.
A method aspect is directed to a method of making a radio frequency (RF) and fluid coupler for a subterranean assembly that includes an RF antenna and a coaxial transmission line connected thereto. The coaxial transmission line includes an inner conductor and an outer conductor surrounding the inner conductor. The subterranean assembly has at least one fluid passageway therein. The method may include forming an electrically conductive hollow body that includes a plurality of electrically conductive segments connected together in end-to-end relation at respective joints to provide an outer electrical pathway to connect to the outer conductor of the coaxial transmission line. The method may also include forming an elongate conductive member to extend within the electrically conductive hollow body to provide an inner electrical pathway to connect to the inner conductor of the coaxial transmission line. The method may further include positioning a respective dielectric pressure barrier between the elongate conductive member and adjacent portions of the electrically conductive hollow body adjacent each of a pair of joints to define at least one fluid chamber to connect to the at least one fluid passageway of the subterranean assembly. A fluid port may be formed that is connected to the at least one fluid chamber.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments.
Referring initially to
The RF antenna 41 may be a dipole antenna, for example, or any other type of antenna, and may be a liner, for example, a slotted liner, as will be appreciated by those skilled in the art. The subterranean assembly 40 also has a fluid passageway 46 therein, for example, for cooling fluid for the coaxial transmission line 42. The fluid passageway 46 may be particularly advantageous for the passage of a solvent, steam, or other fluid for use in the recovery of hydrocarbon resources. Of course, the subterranean assembly 40 may have any number of fluid passageways therein, for example, a single fluid passageway. Further details of fluid passageways will be described in detail below.
The coaxial transmission line 42 includes an inner conductor 47 and an outer conductor 48 surrounding the inner conductor. The coaxial transmission line 42 may be coupled in the wellbore, which may be laterally extending, to various components, for example, the antenna 41, one or more chokes 51, a tool head assembly 52, a guide string 53, and other components, as will be appreciated by those skilled in the art. Example subterranean assemblies and coaxial transmission lines can be found in application Ser. Nos. 14/076,501, 14/491,530, 14/491,563, and 14/491,545, all of which are assigned to the present assignee, and the entire contents of each of which is hereby incorporated by reference.
Referring now additionally to
Referring briefly to
The electrically conducive hollow body 21 provides an outer electrical pathway to connect to the outer conductor 48 of the coaxial transmission line 42. It will be appreciated that any number of electrically conducive segments may be used, and coupled in the end-to-end relation, for example.
The electrically conductive hollow body 21 illustratively varies in diameter or width along a length thereof. For example, the electrically conductive hollow body 21 changes diameter adjacent an output fluid port 25. The changing diameter may advantageously allow for transitions between different sized, for example, from non-standard to standard, electrically conductive hollow bodies and/or RF transmission lines while maintaining thermal control. A valve 71 is coupled to the output fluid port 25.
A respective seal 26a-26c is between adjacent electrically conductive segments 22a, 22b at the respective joint (
A respective RF contact 27a-27c is between adjacent electrically conductive segments 22a, 22b at respective joints, which may be slip joints. Each RF contact 27a-27c is illustratively in the form of a conductive wound spring and has a generally rectangular shape, and for example may be considered a watch band RF contact (
An elongate conductive member 31 extends within the electrically conductive hollow body 21 to provide an inner electrical pathway to connect to the inner conductor of the coaxial transmission line 42. For example, the elongate member 31 along with the electrically conducive hollow body 21 may be coupled to an RF source above the subterranean formation 43 so that RF energy is supplied at to the antenna 41 via the RF transmission line 42.
A respective dielectric pressure barrier 32a-32c is between the elongate conductive member 31 and adjacent portions of the electrically conductive hollow body 21 adjacent each of a pair of joints defining respective fluid chambers 33a, 33b to connect to a respective fluid passageway or port. The fluid output port 25 is connected to the fluid chamber 33b. While a fluid port 25 is described as an output port, the fluid port may be an input fluid port corresponding to and connecting with a particular fluid passageway and/or fluid flow direction.
The elongate conductive member 31 may be hollow or tubular to define a fluid passageway 34 therein. Slots 37 or openings may be in the elongate conductive member 31 adjacent the fluid chamber 33b to allow the passage of a fluid from within the elongate conductive member through the fluid chamber and to the output fluid port 25. In particular, two uppermost dielectric pressure barriers 32a, 32b act as pressure barriers for the fluid with the uppermost dielectric pressure barrier 32a being redundant. The dielectric pressure barriers 32a-32c restrict the fluid from the fluid passageway 34 to the fluid chamber 33b thus allowing the fluid to flow thorough the output fluid port 25. The fluid chamber 33a is redundant is and is not coupled to a fluid port. In other embodiments, the fluid chamber 33a may be coupled to a fluid port and/or fluid passageway, and may not be redundant.
The RF and fluid coupler 20 may also include further electrically conductive hollow segments 22c, 22d coupled between the subterranean assembly 40 and the electrically conductive hollow segments 22a, 22b. A respective dielectric pressure barrier is not coupled between adjacent further electrically conductive segments 22c, 22d at respective joints therebetween. A fluid inlet port 66 is coupled to a fluid passageway 36 defined by an annulus, for example an outer annulus, of each of the further electrically conductive segments 22c, 22d, and particular, electrically conductive segment 22d. Of course, the inlet port 66 may be coupled to or in fluid communication with another fluid passageway or annulus. As will be appreciated by those skilled in the art, a fluid, for example a cooling fluid, may be passed through the fluid input port 66 and may return via the fluid passageway 34 to the fluid cavity 33b and through the fluid output port 25. A valve 72 is coupled to the fluid output port 66.
Illustratively, the outer fluid passageway 36 is blocked from an annulus or corresponding fluid passageway of an adjacent further electrically conductive segment 22c. This allows, in this configuration, the fluid passage from the fluid inlet port 66 to flow in the downhole direction. Of course, any number of annuli or fluid passageways may exist and each passageway may be for any type of fluid.
Another fluid passageway 35 is defined by the space between the electrically conductive hollow body 21 and the elongate conductive member 31. The fluid passageway 35 may also be for dielectric fluid, for example, and may allow the passage of a dielectric such as N2. The dielectric pressure barrier 32c may thus act as a pressure barrier for the fluid, for example, for the N2.
Each respective dielectric pressure barrier 32a-32c may include quartz fiber, for example, to provide increased strength and CTE matching. Of course each respective dielectric pressure barrier 32a-32c may be another type of material, for example a fiberglass cloth (i.e., S-Glass), a polymer, such as for example, polyether ether ketone (PEEK) or fiber reinforced perfluoroalkoxy alkanes (PFA). Each dielectric pressure barrier 32a-32c may be particularly advantageous for reducing a blow out associated with the corresponding fluid passageway 34, 35. Multiple or redundant dielectric pressure barriers 32a, 32b may be associated with a given fluid passageway 34 as described above.
It may be desirable for each respective dielectric pressure barrier 32a-32c and electrically conductive hollow body 21 to have a coefficient of thermal expansion (CTE) within ±10% of each other, for example. As will be appreciated by those skilled in the art, a relatively small, if any, CTE mismatch is particularly advantageous for maintaining or controlling thermal growth, and, thus, may provide increased ease of maintenance.
Each of the electrically conductive segments 22a, 22b illustratively has an enlarged width flange 61 at each joint, and also has fastener receiving passageways 62 therein (
As will be appreciated by those skilled in the art, the RF and fluid coupler 20 may be particularly advantageous for the transmission of RF energy into a well for purpose of heating hydrocarbon resources, for example by meeting ECRB and API well control and strength standards in a pressure vessel body, i.e., fluid chamber, and by controlling multiple pressuring fluid passageways. Additionally, the apparatus may provide increased containment and isolation of hydrocarbon resources, for example, in the event of a failure. RF power transmission losses into the well may also be reduced.
The RF and fluid coupler 20 described herein may also provide increased pressure containment that is compatible with hydrocarbon chemicals, for example, and may also provide increased isolation of the fluid chambers through the use of the dielectric pressure barrier 32a-32c. Still further, the RF and fluid coupler 20 may provide for seal testing and pressure balancing of multiple annuli or fluid passageways, and isolation of high to low pressure zones. Gas pressurization may also advantageously maintain voltage standoff, as will be appreciated by those skilled in the art.
Referring now to
Similar to the embodiments described above, the electrically conductive hollow body 21″ illustratively varies in diameter or width along a length thereof. For example, the electrically conductive hollow body 21″ changes diameter adjacent an output fluid port 25″. A valve 71″ is coupled to the output fluid port 25″.
A respective seal 26a″-26d″ is between adjacent electrically conductive segments 22a″-22d″ at the respective joint. Each seal 26a″-26d″ may be in the form of a ring gasket (i.e., an O-ring), for example, and be similar to those described above.
In the present embodiment, the electrically conductive material layer 24a″, 24b″ defines an RF contact between adjacent electrically conductive segments 22a″-22c″ at respective joints. An elongate conductive member 31″ extends within the electrically conductive hollow body 21″ to provide an inner electrical pathway to connect to the inner conductor of the coaxial transmission line. For example, the elongate member 31″ along with the electrically conducive hollow body 21″ may be coupled to an RF source above the subterranean formation so that RF energy is supplied at to the antenna via the RF transmission line.
A respective dielectric pressure barrier 32a″-32c″ is between the elongate conductive member 31″ and adjacent portions of the electrically conductive hollow body 21″ adjacent each of a pair of joints defining respective fluid chambers 33a″, 33b″ to connect to a respective fluid passageway or port. The fluid output port 25″ is connected to the fluid chamber 33b″. While a fluid port 25″ is described as an output port, the fluid port may be an input fluid port corresponding to and connecting with a particular fluid passageway and/or fluid flow direction.
The elongate conductive member 31″ may be hollow or tubular to define a fluid passageway 34″ therein. Slots 37a″ or openings may be in the elongate conductive member 31″ adjacent the fluid chamber 33b″ to allow the passage of a fluid from within the elongate conductive member through the electrically conductive tube 29″, which also has slots 37b″ therein adjacent the slots 37a″, and through the fluid chamber and to the output fluid port 25″. Similar to the embodiment described above, a fluid inlet port 66″ is coupled to a fluid passageway 36″ defined by an annulus, for example an outer annulus, of each of the electrically conductive segments 22c″, 22d″. A valve 72″ is coupled to the fluid output port 66″. Another fluid passageway 35″ is defined by the space between the electrically conductive hollow body 21″ and the elongate conductive member 31″.
A method aspect is directed to a method of making a radio frequency (RF) and fluid coupler 20 for a subterranean assembly 40 that includes an RF antenna 41 and a coaxial transmission line 42 connected thereto. The coaxial transmission line 42 includes an inner conductor 47 and an outer conductor 48 surrounding the inner conductor. The subterranean assembly 40 has at least one fluid passageway 46 therein. The method includes forming an electrically conductive hollow body 21 that includes a plurality of electrically conductive segments 22a-22d connected together in end-to-end relation at respective joints to provide an outer electrical pathway to connect to the outer conductor 48 of the coaxial transmission line 42. The method also includes forming an elongate conductive member 31 to extend within the electrically conductive hollow body 21 to provide an inner electrical pathway to connect to the inner conductor 47 of the coaxial transmission line 42. The method further includes positioning a respective dielectric pressure barrier 32a-32d between the elongate conductive member 31 and adjacent portions of the electrically conductive hollow body 21 adjacent each of a pair of joints to define at least one fluid chamber 33a, 33b to connect to the at least one fluid passageway 46 of the subterranean assembly 40. The method further includes forming a fluid port 25 connected to the at least one fluid chamber 33b.
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.
