The invention relates to high pressure seals. More particularly, the invention relates to high pressure seals for washpipes.
In a drilling system, high pressure fluids are sent down the bore hole through a washpipe and a drill string, and ultimately to a drill motor at the bottom of the drill string. The fluid is supplied to the motor for driving cutting tools under very high pressure. A seal is necessary at the joint between the non-rotary upper connection assembly and the rotary lower connection assembly to prevent leakage of the drilling fluid to the outside. The joint is between the upper connection assembly, which includes a housing for the stator assembly, and the lower connection assembly, which includes the rotor assembly that is affixed to and rotates with the drill string. The rotor and housing are sometimes collectively referred to as a “cartridge.” The seal for this joint is referred to as a washpipe seal.
A typical wash pipe seal assembly is shown in
Still referring to
In greater detail, still referring to
A static upper seal assembly 30 surrounds upper end of washpipe 16. Static upper seal assembly 30 includes upper packing nut 32. A lower end of upper packing nut 32 defines angular recess 42 on an inside surface. Upper ring 50 is received within upper packing nut 32. Upper ring 50 has an upper surface 52 defining an annular seal receptacle for receiving seal 58.
Upper elastomeric v-ring seal 60 is located within an annular space defined by upper ring 50 and washpipe 16. Upper elastomeric v-ring seal 60 has an inner surface 62 for engaging washpipe 16. Upper elastomeric v-ring seal 60 additionally includes a lower protrusion that is received within annular recess 42.
A dynamic lower seal assembly designated generally 70 surrounds a lower end of washpipe 16. Dynamic lower seal assembly includes lower packing nut 72. Lower packing nut 72 defines vertical wall 78 that connects an upper end and a lower end. Lower packing nut 72 additionally defines grease port 86 on vertical wall 78.
First elastomeric v-ring seal 90 defines an upper protrusion received within annular recess 82 defined by an upper end of lower packing nut 72. First elastomeric v-ring seal 90 has a downwardly protruding inside seal portion for communicating with washpipe 16 and has a downwardly protruding outside seal portion.
A first bronze spacer ring 100 is located below first elastomeric v-ring seal 90. First bronze spacer ring 100 has a vertical portion that extends between downwardly protruding outside seal portion of first elastomeric v-ring 90 and an inside surface of vertical wall 78 of lower packing nut 72. First bronze spacer ring 100 defines a horizontal portion that defines grease passageway 108 for delivering grease from grease port 86 to an area adjacent washpipe 16.
A second elastomeric v-ring seal 110 has an upper protrusion received within an annular recess of first bronze spacer ring 100. Second elastomeric v-ring seal 110 has a downwardly protruding inside seal portion for communicating with washpipe 16. Second elastomeric v-ring seal 110 also has a downwardly protruding outside seal section.
A second bronze spacer ring 120 is located below second elastomeric v-ring seal 110. Second bronze spacer ring 120 has a vertical portion between the downwardly protruding outside seal portion of second elastomeric v-ring 110 and an inside surface of vertical wall 78 of lower packing nut 72. A lower surface of a horizontal portion of second bronze ring 120 defines an annular recess. An upper surface of the horizontal portion is in sealing engagement with a lower end of the downwardly protruding outside seal portion of second elastomeric v-ring seal 110.
A third elastomeric v-ring seal 130 has an upper protrusion received within the annular recess of second bronze spacer ring 120. Third elastomeric v-ring seal 130 has a downwardly protruding inside seal portion for communicating with washpipe 16. Third elastomeric v-ring seal 130 additionally has a downwardly protruding outside seal portion.
A third bronze spacer ring 140 is located below third elastomeric v-ring seal 130. Third bronze spacer ring 140 has a vertical portion between the downwardly protruding outside seal portion of third elastomeric v-ring seal 130 and an inside surface of vertical wall 78 of lower packing nut 72. Third bronze spacer ring 140 defines a horizontal portion. A lower surface of the horizontal portion defines an annular seal receptacle 146 for receiving seal 150.
The high pressure seal assembly of the disclosure includes a lower seal assembly and an upper seal assembly, wherein the high pressure seal assembly is designed to withstand exceptionally high pressures, such as 10,000 to even 15,000 psi. Applicant's high pressure seal assembly may replace, via a retrofit, seal assemblies that are typically found in the field.
In one embodiment, the seal assembly of the disclosure includes a high pressure seal, e.g., a Viton D90 ring with a PTFE sealing surface located in a steel ring having a simple cross-section. Identical rings and seals are stacked three high, which simplifies assembly as compared to the differently shaped first, second, and third elastomeric v-ring seals and bronze spacer rings of the prior art. The high pressure seal of the disclosure has a self-lubricating polymer inner surface, such as PTFE or Teflon that eliminates difficulties associated with greasing the seal assembly through a grease port. Difficulties associated with greasing a seal assembly through a grease port include underfilling or overfilling the seal assembly with grease and uneven grease distribution. The high pressure elastomeric seal that is received within a ring defines an inner leg for contacting a washpipe and defines an outer leg in contact with the ring. The inner leg, outer leg, and seal base define a seal cavity. A seal insert ring, such as an o-ring, is received within the seal cavity for directing pressure process toward the seal base for mitigating a spreading force that may otherwise act on the elastomeric seal. Directing pressure towards the seal base decreases the possibility of the seal being forced through a gap between the ring and washpipe. All adjacent ring surfaces are provided with O-rings to prevent a leak path. Additionally, an excluder seal is provided above the 3-ring stack to prevent an ingress of particulates into the seal assembly.
Advantages of the seal assembly of the disclosure include an assembly having identical components, a self-lubricating seal face to avoid difficulties associated with applying grease through a grease port, simply shaped steel rings that are more durable than bronze and that are easily machined, seals between adjacent rings, the addition of an excluder seal, and a specially shaped high pressure elastomeric seal with integral o-ring for avoiding seal extrusion.
The upper seal assembly utilizes an identical seal to the seal used in the lower seal assembly described above, except that the seal is inverted for use in the upper seal assembly. Applicant's upper seal assembly utilizes an annular plate to provide a floor for supporting the seal and for covering the v-shaped indentation provided in the upper packing nut to receive prior art v-rings.
Advantages of Applicant's assembly further include utilizing the same high pressure ring and seal assembly for the upper seal assembly and for the lower seal assembly to facilitate ease of manufacture and assembly.
Because Teflon is easily damaged when a pipe is located within the seal assembly, an installation tool may be employed. The installation tool is sized to be tightly received within the upper seal assembly. The installation tool defines a frusto-conical protrusion for receiving within a lower end of the pipe. As the pipe is lowered onto the frustum, the pipe is centered within the upper seal assembly, thereby preventing any inadvertent contact between the potentially rough pipe end and the delicate Teflon seal surface. A sketch of the installation tool is provided on the attached figures.
Referring now to
Static upper seal assembly is designated generally 220 and surrounds upper end 208 of washpipe 206. Static upper seal assembly 220 includes upper packing nut 230 that defines lower end 232 and upper end 233. Lower end 232 has an inside surface 234. Lower end 232 defines upper seal washpipe orifice 236 for receiving washpipe 206. Inside surface 234 defines annular recess 237.
Upper seal ring 240 is received within upper packing nut 230. Upper seal ring 240 has an upper surface defining annular seal receptacle 242. Upper seal ring 240 also defines interior protrusion 244 having an upper surface and a lower surface. The upper surface of interior protrusion 244 mates with the lower surface of flange 212 of washpipe 206. Upper seal ring 240 has a lower surface defining plate indentation 246.
A seal, such as o-ring 248, is received in annular seal receptacle 242. O-ring 248 is provided for forming a seal between the upper surface of upper seal ring 240 and the gooseneck.
Annular plate 250 surrounds washpipe 206. Annular plate 250 is received within plate indentation 246 of upper ring 240 and covers annular recess 237 on inside surface 234 of lower end 232 of upper packing nut 230.
As shown in greater detail in
Dynamic lower seal assembly is designated generally 270 (
An excluder seal ring is designated generally 300 (
A first seal ring 310 (
Second seal ring 330 (
First outer seal, such as first outer o-ring 350, is located in first seal receptacle 320 for sealing engagement between lower surface 318 of first ring 310 and upper surface 334 of second seal ring 330.
Third seal ring 360 (
Second outer seal, such as second outer o-ring 380, is located in second seal receptacle 340 for sealing engagement between lower surface 338 of second ring 330 and upper surface 364 of third seal ring 360.
Lower ring 390 (
Third outer seal, such as third outer o-ring 400, is located in third seal receptacle 370 is for sealing engagement between lower surface 368 of third ring 360 and upper surface 392 of lower ring 390.
Fourth seal 410, such as fourth o-ring, is located in base ring receptacle 396 for sealing engagement between lower surface 394 of lower ring 390 and an upper surface of shaft 204.
A first annular space 420 is defined by intermediate surface 316 of first seal ring 310, the vertical portion of first ring 310, upper surface 334 of second seal ring 330, and washpipe 206.
A first high pressure seal 430 (
A second annular space 440 is defined by intermediate surface 336 of second seal ring 330, the vertical portion of second seal ring 330, upper surface 364 or third seal ring 360, and washpipe 206.
A second high pressure seal 450 (
A third annular space 460 is defined by intermediate surface 366 of third seal ring 360, the vertical portion of third seal ring 360, the upper surface 392 of lower ring 390, and washpipe 206.
Third high pressure seal 470 (
In a preferred embodiment, second seal ring 330 and third seal ring 360 have an identical construction to that of first seal ring 310, shown in an enlarged view of
In practice, a user should apply grease under sealing lip 304 of excluder seal ring 300. The excluder seal ring 300 is installed in lower packing nut 280. Grease should be applied to inner diameter of seal rings 310, 330, and 360 as well as inner surfaces 262, 432, 452, and 472 of high pressure seals 260, 430, 450, and 470, respectively. Lower ring 390 is then located in lower packing nut 280. Greasing holes 287 should be blocked up.
Referring now to
Thus, the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those of ordinary skill in the art. Such changes and modifications are encompassed within the spirit of this invention as defined by the claims.
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