US20080230274A1

US20080230274A1 - Top drive washpipe system

Info

Publication number: US20080230274A1
Application number: US12/012,616
Authority: US
Inventors: Svein Stubstad
Original assignee: National Oilwell Varco LP
Current assignee: National Oilwell Varco LP
Priority date: 2007-02-22
Filing date: 2008-02-04
Publication date: 2008-09-25
Also published as: CA2678686A1; EP2126269A1; WO2008102175A1

Abstract

A top drive system for wellbore operations, the top drive system, in at least certain aspects, including a motor, a main shaft driven by the motor, the main shaft having a top end and a bottom end, a speed reduction system interconnected with the main shaft, a washpipe shaft interconnected with the speed reduction system for driving the washpipe shaft at a speed of rotation less than a speed of rotation of the main shaft. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 C.P.R. 1.72(b).

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present invention and the application for this patent claim priority under the U.S. Patent law §120 of U.S. Application Ser. No. 60/902,798 filed Feb. 22, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention is directed to wellbore drilling top drive systems; to washpipe apparatuses for such systems; and to sealing systems for rotating members.
2. Description of Related Art
Drilling fluids are transmitted to drilling swivels and top drive drilling systems through a high-pressure swivel apparatus known as a “washpipe” with a seal known as a “washpipe packing” assembly. This packing assembly consists of a tubular component which is held stationary, and through which the drilling fluid flows under high pressure. A rotating seal assembly of contact lip seals is mechanically fixed to and rotates with the main shaft of the top drive or swivel, and forms a dynamic seal against the outer surface of the tubular washpipe as the main shaft rotates while drilling. Due to the high pressures and surface speeds involved in this arrangement, service life of the washpipe packing is limited. Drilling fluid leaks are therefore common on many drilling rigs, causing contamination and damage to associated components and environmental disruption.
The prior art discloses a variety of top drive systems; for example, and not by way of limitation, the following U.S. patents present exemplary top drive systems and sealing assemblies: U.S. Pat. Nos. 4,458,768; 4,807,890; 4,984,641; 5,433,279; 6,276,450; 4,813,493; 6,705,405; 4,800,968; 4,878,546; 4,872,577; 4,753,300; 6,007,105; 6,536,520; 6,679,333; 6,923,254.
In top drives and rotary drilling the washpipe typically sealingly engages a set of circumferential seals contained within a seal housing. Often, the washpipe remains stationary while the seals and the seal housing rotate. Such seal assemblies have conventionally included a series of reinforced, elastomeric, chevron-type seals interspersed with a series of reinforcing back-up rings. In certain prior art systems, one seal is exposed to full hydraulic pressure on one side, and atmospheric pressure on the opposite side. Full differential pressure of the drilling mud acts on one seal until that seal fails and the next seal in the assembly then acts as the primary seal. Some prior art swivel designs have sought to compensate for potential run-out and offset problems by allowing the washpipe and the seal housing to articulate.

BRIEF SUMMARY OF THE INVENTION

The present invention, in certain aspects, provides a shaft sealing assembly in which an auxiliary shaft rotated by a rotating main shaft is connected to and rotates with the shaft via a speed reducer, e.g., a gear drive apparatus, between the main shaft and the auxiliary shaft so that the auxiliary shaft rotates at a reduced speed compared to the speed of the main shaft, e.g. about one-half the main shaft speed, thus exposing seals dynamically sealing against the auxiliary shaft to a surface which is moving at the reduced speed, thus enhancing seal life.
In one particular aspect the main shaft is the main drive shaft of a top drive used in wellbore operations, e.g. drilling operations, and the auxiliary shaft is in fluid communication with a washpipe through which drilling fluid or mud flows to and through the top drive system.
The present invention discloses, in certain embodiments, a top drive system with a drive motor; a drive quill or main shaft; a gear system coupled to the drive motor; a top drive support system for supporting various items; and a washpipe shaft according to the present invention connected with the top drive main shaft via a speed reducer for rotation at a speed less than that of the main shaft to enhance the life of seal assemblies, e.g. with packings used to seal against the washpipe shaft.
Accordingly, the present invention includes features and advantages which are believed to enable it to advance top drive shaft sealing technology. Characteristics and advantages of the present invention described above and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments and referring to the accompanying drawings.
Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures, functions, and/or results achieved. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention.
What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, there are other objects and purposes which will be readily apparent to one of skill in this art who has the benefit of this invention's teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide:
New, useful, unique, efficient, non-obvious sealing for drive shafts, for top drive shafts, sealing arrangements for such shafts, and methods of their use.
The present invention recognizes and addresses the problems and needs in this area and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention's realizations, teachings, disclosures, and suggestions, various purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent's object to claim this invention no matter how others may later attempt to disguise it by variations in form or additions of further improvements.
The Abstract that is part hereof is to enable the U.S. Patent and Trademark Office and the public generally, and scientists, engineers, researchers, and practitioners in the art who are not familiar with patent terms or legal terms of phraseology to determine quickly from a cursory inspection or review the nature and general area of the disclosure of this invention. The Abstract is neither intended to define the invention, which is done by the claims, nor is it intended to be limiting of the scope of the invention or of the claims in any way.
It will be understood that the various embodiments of the present invention may include one, some, or all of the disclosed, described, and/or enumerated improvements and/or technical advantages and/or elements in claims to this invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain preferred embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or equivalent embodiments.

FIG. 1 is a schematic view of a prior art top drive drilling system.

FIG. 2 is a front view of a top drive system according to the present invention with washpipe apparatus according to the present invention.

FIG. 3 is a cross-section view of one embodiment of part of the system of FIG. 2.

FIG. 4 is a cross-section of one embodiment of part of the system of FIG. 2.

FIG. 4A is a schematic side cross-section view of the system according to the present invention.

FIG. 5 is a cross-section view of part of the embodiment of FIG. 4.

Presently preferred embodiments of the invention are shown in the above-identified figures and described in detail below. Various aspects and features of embodiments of the invention are described below and some are set out in the dependent claims. Any combination of aspects and/or features described below or shown in the dependent claims can be used except where such aspects and/or features are mutually exclusive. It should be understood that the appended drawings and description herein are of preferred embodiments and are not intended to limit the invention or the appended claims. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. In showing and describing the preferred embodiments, like or identical reference numerals are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.
As used herein and throughout all the various portions (and headings) of this patent, the terms “invention”, “present invention” and variations thereof mean one or more embodiment, and are not intended to mean the claimed invention of any particular appended claim(s) or all of the appended claims. Accordingly, the subject or topic of each such reference is not automatically or necessarily part of, or required by, any particular claim(s) merely because of such reference. So long as they are not mutually exclusive or contradictory any aspect or feature or combination of aspects or features of any embodiment disclosed herein may be used in any other embodiment disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a typical prior art drilling system with a derrick DK supporting a top drive TD which rotates drill pipe DP. The top drive is supported from a travelling block TB beneath a crown block CB. A drawworks, DS, on a rig floor RF raises and lowers the top drive. The top drive moves on a guide track GT.
FIG. 2 shows a system S according to the present invention with a top drive 1 with a drive motor 2; a gear system 3 coupled to the top drive 1 with a bearing support 4 and support links 4 a; a washpipe apparatus 10 with a washpipe shaft according to the present invention; an elevator load ring 5; a mud saver system 9; a lower internal blowout preventer 6; a saver sub 7; a gooseneck 24; and a pipe gripper 8 with supports 8A connected to the elevator load ring 5.
The present inventors have recognized the problems associated with the rotation of a shaft with respect to packing or seals and have realized that effective reduction of the speed of shaft rotation can enhance seal life and reduce seal wear.
By reducing the surface speed at which the seals effectively operate, the present invention extends the service life of washpipe packing. Instead of the packing rotating at main shaft speed against a stationary washpipe, the present invention provides a speed reducing mechanism (e.g. a gear drive apparatus) which rotates a washpipe shaft at, e.g., one-half the speed of the main shaft, thus the washpipe packing is not subjected to the full speed of the main shaft. In one embodiment of the present invention, a similar dynamic sealing assembly is, optionally, added at the upper, formerly stationary, end of the washpipe. By rotating the washpipe shaft with the main shaft, but at a lower speed than the main shaft, e.g. at one-half main shaft speed, the or each of the sealing assemblies are only subjected to one-half the original surface speed (thus one half the original contact with a rotating surface), increasing the overall service life of the packing and washpipe assembly. Rotation of the washpipe shaft is driven by the main shaft through a speed reducing mechanism.
As shown in FIG. 3 an apparatus 10 according to the present invention has a main washpipe body 12 disposed above and in fluid communication with a main shaft M of the top drive system S. A washpipe shaft 70 projects into an upper packing assembly 16 and rotates with the main shaft M (but is connected to the main shaft only via a gear system described below). Upper and lower packing assemblies 16 and 18 respectively, have seals which seal against the washpipe shaft 70.
Drilling mud flows through a channel 22 of the gooseneck 24 into an interior 70 a of the washpipe shaft 70 and from there down a channel C through the main shaft M into the drill pipe.
Packing 15 of the upper packing assembly 16 does not rotate with the washpipe shaft 70. The outer surface of the washpipe shaft 70 rotates against the packing 15. The gooseneck 24 is connected to gooseneck support 25 with bolts 26. For assembly purposes a support 28 is connected to the upper packing assembly 16 with a bolt (or bolts) 32 connected to a housing 34. A bolt (or bolts) 36 connect the lower packing assembly 18 adjacent the main shaft M. Following assembly, the support 28 and the bolts 32, 36 are deleted.
A primary gear 40 is secured to and rotates with the main shaft within the housing 34. Teeth 40 a on the primary gear 40 mesh with teeth 42 a on planetary gears 42 which are mounted on shafts 44 of a gear carrier 46. Ball bearings 48 in a lower part 52 of the housing 34 and ball bearings 49 under an upper part 54 of the housing 34 isolate the housing 34 from the rotation of the main shaft M, rotation of the primary gear 40, and rotation of the planetary gears 42. A shield 62 shields items below it from falling drilling mud and inhibits the leakage or flow of mud from going into apparatuses below the shield 62, e.g. a top drive gear box.
FIGS. 4 and 5 show another embodiment of a system 100 according to the present invention useful as a washpipe apparatus in the system S of FIG. 2. An s-pipe extension 101 is connected to a gooseneck 102 (sometimes referred to as a washpipe apparatus). Drilling mud flows through a channel 101 a in the s-pipe extension 101 into a channel 102 a through the gooseneck 102 down into a channel 121 of a washpipe shaft 120 and then to a channel 141 through a top drive shaft 140 driven by a top drive motor 105 (e.g. a rotating shaft projecting from a top drive gear box 104 (shown in dotted line). A connector 103 with seals 103 a, 103 b, connects the s-pipe extension 101 to the gooseneck 102.
An upper seal carrier 106 connected too the gooseneck 102 houses seal assemblies 107 (which include seal carriers and seals) which seal against an outer surface of the washpipe shaft 120. The upper seal holder 106 maintains the top of the washpipe shaft 120 in place. A lower seal holder 108 connected to the shaft 140 houses seal assemblies 109 (which include seal carriers and a seal) which seal against an outer surface of the washpipe shaft 120. The lower seal carrier 108 maintains the bottom of the washpipe shaft 120 in place.
A speed reducer 160 interconnected between the shaft 140 and the washpipe shaft 120 reduces the speed of the washpipe shaft 120 as compared to the speed of the shaft 140. Thus the seals 107 and 109 seal against a shaft (the washpipe shaft 120) rather than against the lower shaft (the top drive shaft 140) and the seals are, therefore, subjected to a shaft surface rotating at a speed less than (e.g., in certain aspects, at least 25% less than, and, in other aspects about 50% less than) the speed of the lower shaft.
Ports 106 p and 108 p house bolts 106 b, 108 b, respectively, which maintain the seal assemblies 107, respectively, in place. Bolts 102 b bolt the gooseneck to other structure. A torque arrester 112 is connected to the washpipe, e.g. to the upper seal holder 106 and to the speed reducer 160. This torque arrester 112 prevents the ring housing 164 of the speed reducer 160 from rotating with other parts of the speed reducer 160. The ring housing 164 provides a housing for bearings and gears of the speed reducer 160. A splash shield 114 is connected to the shaft 140.
A sun gear 162 is connected to the lower seal holder 108 and rotates with the shaft 140. Planetary gears 166 (e.g., but not limited to, four planetary gears) mounted on shafts 167 to a planetary gear carrier 168 mesh with and are driven by the sun gear 162. Splines 169 on the planetary gear carrier 168 mesh with corresponding splines 128 on the washpipe shaft 120 to rotatively drive the washpipe shaft 120.
The ring housing 164 houses a bearing assembly 170 with bearings 172 between the ring housing 164 and the sun gear 162. The ring housing 164 houses a bearing assembly 174 with bearings 176 between the ring gear and the planetary gear carrier 168. The sun gear and the planetary gears are sized, designed and configured to achieve a desired gear reduction to reduce the speed of the shaft 120 as compared to the speed of the shaft 140. For example, in one particular aspect, the gears are designed so that the shaft 140 rotates twice as fast as the shaft 120. In certain prior systems seals (like the seals 109) were subjected to a shaft (like the shaft 140) rotating at its operational speed and seals (like the seals 107) were held stationary. The seals (like two seals 107; and the seals 109) in systems according to the present invention are now subjected to a shaft rotating at a much lower speed.
FIG. 4A shows schematically a system 200 according to the present invention in which a washpipe shaft 202 connected to a washpipe 204 is interconnected via a speed reduction device 206 to a rotatable top drive shaft 208. Seals 211, 212 seal against the washpipe shaft 202. Both seals are subjected to a surface of the washpipe shaft 202 against which they seal that is rotating at a speed less than the rotational speed of the top drive shaft 208. The seals 211 are in a seal holder 218 connected to the washpipe 204. Although the seals 212 are connected to a lower seal holder 214 that is connected to the top drive shaft 208, the seals 212 only “see” a surface speed of the washpipe shaft 202 which is less than that of the top drive shaft 208 since the washpipe shaft 202 and the top drive shaft 208 are rotating in the same direction. The speed reduction device 206 may be any suitable speed reducer, including, but not limited to, a gear system.
The present invention, therefore, provides in at least certain embodiments, a top drive system for wellbore operations, the top drive system having: a main shaft with a main shaft channel therethrough; drive apparatus for rotating the main shaft at a main shaft speed; a speed reducer apparatus connected to the main shaft; a washpipe shaft connected to the speed reducer apparatus so that the washpipe shaft is rotatable by the speed reducer apparatus at a washpipe shaft speed less than the main shaft speed; the washpipe shaft having a top end and a bottom end, and a washpipe shaft channel therethrough; a washpipe having a washpipe channel therethrough, the washpipe shaft channel in fluid communication with the washpipe channel; the washpipe shaft channel in fluid communication with the main shaft channel; a first seal holder connected to the washpipe and holding first seal assemblies for sealing against the top end of the washpipe shaft; and a second seal holder connected to the main shaft and holding second seal assemblies for sealing against the second end of the washpipe. Such a system may have one or some, in any possible combination, of the following: the speed reducer apparatus reducing the washpipe shaft speed to at least 25% less than the main shaft speed; the speed reducer apparatus reducing the washpipe shaft speed to about 50% of the main shaft speed; the speed reducer apparatus is a gear system including first gear apparatus connected to the main shaft and second gear apparatus connected to the washpipe shaft, the first gear apparatus for driving the second gear apparatus; the first gear apparatus includes a first gear, the second gear apparatus includes a plurality of second gears, and the first gear drives the plurality of second gears to rotate the washpipe shaft; the speed reducer apparatus having a ring housing, and a torque arrester connected to the ring housing and to the washpipe; wherein the torque arrester is connected to the first seal holder which is connected to the washpipe; and/or wherein the drive apparatus includes a top drive motor and a top drive gear system driven by the top drive motor.
The present invention, therefore, provides in at least certain embodiments, a top drive system for wellbore operations, the top drive system having: a main shaft with a main shaft channel therethrough; drive apparatus for rotating the main shaft at a main shaft speed; a speed reducer apparatus connected to the main shaft; a washpipe shaft connected to the speed reducer apparatus so that the washpipe shaft is rotatable by the speed reducer apparatus at a washpipe shaft speed less than the main shaft speed; the washpipe shaft having a top end and a bottom end, and a washpipe shaft channel therethrough; a washpipe having a washpipe channel therethrough, the washpipe shaft channel in fluid communication with the washpipe channel; the washpipe shaft channel in fluid communication with the main shaft channel; a first seal holder connected to the washpipe and holding first seal assemblies for sealing against the top end of the washpipe shaft; a second seal holder connected to the main shaft and holding second seal assemblies for sealing against the second end of the washpipe; the speed reducer apparatus reduces the washpipe shaft speed to about 50% of the main shaft speed; the speed reducer apparatus is a gear system including first gear apparatus connected to the main shaft and second gear apparatus connected to the washpipe shaft; the first gear apparatus for driving the second gear apparatus; and the drive apparatus includes a top drive motor and a top drive gear system driven by the top drive motor.
The present invention, therefore, provides in at least certain embodiments, a method for dynamically sealing a drive shaft of a top drive system, the top drive system suitable for wellbore operations, the method including: rotating a washpipe shaft of a top drive system; sealing against a top end and a bottom end of the washpipe shaft, the washpipe shaft being part of the top drive system, the top drive system having a main shaft with a main shaft channel therethrough, drive apparatus for rotating the main shaft at a main shaft speed, a speed reducer apparatus connected to the main shaft, a washpipe shaft connected to the speed reducer apparatus so that the washpipe shaft is rotatable by the speed reducer apparatus at a washpipe shaft speed less than the main shaft speed, the washpipe shaft having a top end and a bottom end, and a washpipe shaft channel therethrough, a washpipe having a washpipe channel therethrough, the washpipe shaft channel in fluid communication with the washpipe channel, the washpipe shaft channel in fluid communication with the main shaft channel, a first seal holder connected to the washpipe and holding first seal assemblies for dynamically sealing against the top end of the washpipe shaft, a second seal holder connected to the main shaft and holding second seal assemblies for dynamically sealing against the second end of the washpipe, and rotating the washpipe shaft at a speed less than the speed of the main shaft; wherein the washpipe shaft speed is at least 25% less than the main shaft speed; wherein the washpipe shaft speed is about 50% of the main shaft speed; wherein the speed reducer apparatus is a gear system including first gear apparatus connected to the main shaft and second gear apparatus connected to the washpipe shaft, and the first gear apparatus for driving the second gear apparatus, the method further including: driving the second gear apparatus with the first gear apparatus; wherein the first gear apparatus includes a first gear, the second gear apparatus includes a plurality of second gears, and the first gear is for driving the plurality of second gears to rotate the washpipe shaft, the method further including: driving the plurality of second gears with the first gear to rotate the washpipe apparatus; wherein the speed reducer apparatus has a ring housing, and a torque arrester connected to the ring housing and to the washpipe; wherein the drive apparatus includes a top drive motor and a top drive gear system driven by the top drive motor, the method further including driving the top drive gear system with the top drive motor, and driving the main shaft with the top drive gear system.
The present invention, therefore, provides in at least certain embodiments, a top drive shaft system including: a main shaft with a main shaft channel therethrough; drive apparatus for rotating the main shaft at a main shaft speed; a speed reducer apparatus connected to the main shaft; a washpipe shaft connected to the speed reducer so that the washpipe shaft is rotatable by the speed reducer apparatus at a washpipe shaft speed less than the main shaft speed; the washpipe shaft having a top end and a bottom end, and a washpipe shaft channel therethrough; a washpipe having a washpipe channel therethrough, the washpipe shaft channel in fluid communication with the washpipe channel; and the washpipe shaft channel in fluid communication with the main shaft channel. Such a system may have one or some, in any possible combination, of the following: a first seal holder connected to the washpipe and holding first seal assemblies for sealing against the top end of the washpipe shaft, and a second seal holder connected to the main shaft and holding second seal assemblies for sealing against the second end of the washpipe; wherein the speed reducer apparatus reduces the washpipe shaft speed to at least 25% less than the main shaft speed; and/or wherein the speed reducer apparatus reduces the washpipe shaft speed to about 50% of the main shaft speed; and/or the speed reducer apparatus having a ring housing, and a torque arrester connected to the ring housing and to the washpipe.
The present invention, therefore, provides in at least certain embodiments, a drive shaft system including: a main shaft with a main shaft channel therethrough; drive apparatus for rotating the main shaft at a main shaft speed; a speed reducer apparatus connected to the main shaft; a secondary shaft connected to the speed reducer apparatus so that the secondary shaft is rotatable by the speed reducer apparatus at a secondary shaft speed less than the main shaft speed; the secondary shaft having a top end and a bottom end, and a secondary shaft channel therethrough; a pipe having a pipe channel therethrough, the secondary shaft channel in fluid communication with the pipe channel; the secondary shaft channel in fluid communication with the main shaft channel; first sealing apparatus for sealingly contacting the secondary shaft for sealing a main-shaft secondary-shaft interface; and second sealing apparatus for sealingly contacting a secondary-shaft-pipe interface.
In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to the step literally and/or to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. §102 and satisfies the conditions for patentability in §102. The invention claimed herein is not obvious in accordance with 35 U.S.C. §103 and satisfies the conditions for patentability in §103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. §112. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims. All patents and applications identified herein are incorporated fully herein for all purposes. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are including, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.

Claims

1. A top drive system for wellbore operations, the top drive system comprising

a main shaft with a main shaft channel therethrough,

drive apparatus for rotating the main shaft at a main shaft speed,

a speed reducer apparatus connected to the main shaft,

a washpipe shaft connected to the speed reducer apparatus so that the washpipe shaft is rotatable by the speed reducer apparatus at a washpipe shaft speed less than the main shaft speed,

the washpipe shaft having a top end and a bottom end, and a washpipe shaft channel therethrough,

a washpipe having a washpipe channel therethrough, the washpipe shaft channel in fluid communication with the washpipe channel,

the washpipe shaft channel in fluid communication with the main shaft channel,

a first seal holder connected to the washpipe and holding first seal assemblies for sealing against the top end of the washpipe shaft, and

a second seal holder connected to the main shaft and holding second seal assemblies for sealing against the second end of the washpipe.

2. The top drive system of claim 1 wherein the speed reducer apparatus reduces the washpipe shaft speed to at least 25% less than the main shaft speed.

3. The top drive system of claim 1 wherein the speed reducer apparatus reduces the washpipe shaft speed to about 50% of the main shaft speed.

4. The top drive system of claim 1 wherein

the speed reducer apparatus is a gear system including first gear apparatus connected to the main shaft and second gear apparatus connected to the washpipe shaft,

the first gear apparatus for driving the second gear apparatus.

5. The top drive system of claim 4 wherein

the first gear apparatus includes a first gear,

the second gear apparatus includes a plurality of second gears, and

the first gear drives the plurality of second gears to rotate the washpipe shaft.

6. The top drive system of claim 1 further comprising

the speed reducer apparatus having a ring housing, and

a torque arrester connected to the ring housing and to the washpipe.

7. The top drive system of claim 6 wherein the torque arrester is connected to the first seal holder which is connected to the washpipe.

8. The top drive system of claim 1 wherein the drive apparatus includes a top drive motor and a top drive gear system driven by the top drive motor.

9. A top drive system for wellbore operations, the top drive system comprising

a main shaft with a main shaft channel therethrough,

drive apparatus for rotating the main shaft at a main shaft speed,

a speed reducer apparatus connected to the main shaft,

the washpipe shaft channel in fluid communication with the main shaft channel,

a first seal holder connected to the washpipe and holding first seal assemblies for sealing against the top end of the washpipe shaft,

a second seal holder connected to the main shaft and holding second seal assemblies for sealing against the second end of the washpipe,

the speed reducer apparatus reduces the washpipe shaft speed to about 50% of the main shaft speed,

the first gear apparatus for driving the second gear apparatus, and

the drive apparatus includes a top drive motor and a top drive gear system driven by the top drive motor.

10. A method for dynamically sealing a drive shaft of a top drive system, the top drive system suitable for wellbore operations, the method comprising

rotating a washpipe shaft of a top drive system,

sealing against a top end and a bottom end of the washpipe shaft, the washpipe shaft comprising part of the top drive system, the top drive system comprising a main shaft a with a main shaft channel therethrough, drive apparatus for rotating the main shaft at a main shaft speed, a speed reducer apparatus connected to the main shaft, a washpipe shaft connected to the speed reducer apparatus so that the washpipe shaft is rotatable by the speed reducer apparatus at a washpipe shaft speed less than the main shaft speed, the washpipe shaft having a top end and a bottom end, and a washpipe shaft channel therethrough, a washpipe having a washpipe channel therethrough, the washpipe shaft channel in fluid communication with the washpipe channel, the washpipe shaft channel in fluid communication with the main shaft channel, a first seal holder connected to the washpipe and holding first seal assemblies for dynamically sealing against the top end of the washpipe shaft, a second seal holder connected to the main shaft and holding second seal assemblies for dynamically sealing against the second end of the washpipe, and

rotating the washpipe shaft at a speed less than the speed of the main shaft.

11. The method of claim 10 wherein the washpipe shaft speed is at least 25% less than the main shaft speed.

12. The method of claim 10 wherein the washpipe shaft speed is about 50% of the main shaft speed.

13. The method of claim 10 wherein the speed reducer apparatus is a gear system including first gear apparatus connected to the main shaft and second gear apparatus connected to the washpipe shaft, and the first gear apparatus for driving the second gear apparatus, the method further comprising

driving the second gear apparatus with the first gear apparatus.

14. The method of claim 5 wherein the first gear apparatus includes a first gear, the second gear apparatus includes a plurality of second gears, and the first gear is for driving the plurality of second gears to rotate the washpipe shaft, the method further comprising

driving the plurality of second gears with the first gear to rotate the washpipe apparatus.

15. The method of claim 10 wherein the speed reducer apparatus has a ring housing, and a torque arrester connected to the ring housing and to the washpipe.

16. The method of claim 10 wherein the drive apparatus includes a top drive motor and a top drive gear system driven by the top drive motor, the method further comprising

driving the top drive gear system with the top drive motor, and

driving the main shaft with the top drive gear system.

17. A top drive shaft system comprising

a main shaft with a main shaft channel therethrough,

drive apparatus for rotating the main shaft at a main shaft speed,

a speed reducer apparatus connected to the main shaft,

a washpipe shaft connected to the speed reducer so that the washpipe shaft is rotatable by the speed reducer apparatus at a washpipe shaft speed less than the main shaft speed,

a washpipe having a washpipe channel therethrough, the washpipe shaft channel in fluid communication with the washpipe channel, and

the washpipe shaft channel in fluid communication with the main shaft channel.

18. The top drive system of claim 17 further comprising

19. The top drive system of claim 17 wherein the speed reducer apparatus reduces the washpipe shaft speed to at least 25% less than the main shaft speed.

20. The top drive system of claim 17 wherein the speed reducer apparatus reduces the washpipe shaft speed to about 50% of the main shaft speed.

21. The top drive system of claim 17 further comprising

the speed reducer apparatus having a ring housing, and

a torque arrester connected to the ring housing and to the washpipe.

22. A drive shaft system comprising

a main shaft with a main shaft channel therethrough,

drive apparatus for rotating the main shaft at a main shaft speed,

a speed reducer apparatus connected to the main shaft,

a secondary shaft connected to the speed reducer apparatus so that the secondary shaft is rotatable by the speed reducer apparatus at a secondary shaft speed less than the main shaft speed,

the secondary shaft having a top end and a bottom end, and a secondary shaft channel therethrough,

a pipe having a pipe channel therethrough, the secondary shaft channel in fluid communication with the pipe channel,

the secondary shaft channel in fluid communication with the main shaft channel,

first sealing apparatus for sealingly contacting the secondary shaft for sealing a main-shaft secondary-shaft interface, and

second sealing apparatus for sealingly contacting a secondary-shaft-pipe interface.