US20200308928A1 | 2020-10-01 | |||
EP0105860A2 | 1984-04-18 | |||
US20090301780A1 | 2009-12-10 | |||
US20140000966A1 | 2014-01-02 | |||
US5195754A | 1993-03-23 |
WHAT IS CLAIMED IS: 1. A pressure compensation piston for use with a rotary seal assembly, comprising: a stepped piston having an opening extending there through for positioning the stepped piston about a rotatable shaft of a rotary seal assembly; and a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft. 2. The pressure compensation piston according to Claim 1, wherein the opening includes a diameter (D0) and a circumferential profile extending radially outward into the stepped piston, the rotary seal positioned within the circumferential profile. 3. The pressure compensation piston according to Claim 2, wherein the stepped piston includes a first diameter (D1) portion and a second greater diameter (D2) portion, and further wherein the circumferential profile is located in the first diameter (D1) portion. 4. The pressure compensation piston according to Claim 3, further including one or more linear dynamic seals for sealing the stepped piston relative to a housing surrounding the pressure compensation piston. 5. The pressure compensation piston according to Claim 4, wherein a first linear dynamic seal is positioned at least partially within a radially exterior surface of the first diameter (D1) portion to seal the first diameter (D1) portion relative to the housing, and further wherein a second linear dynamic seal is positioned at least partially within a radially exterior surface of the second diameter (D2) portion to seal the second diameter (D2) portion relative to the housing. 6. A rotary seal assembly, comprising: a housing; a rotatable shaft positioned in a longitudinal opening in the housing, the housing and rotatable shaft forming a cavity there between; and a pressure compensation piston positioned in the cavity, the pressure compensation piston including: a stepped piston having an opening extending there through for positioning the stepped piston about the rotatable shaft; and a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft. 7. The rotary seal assembly according to Claim 6, further comprising an annulus pressure port in the housing, the annulus pressure port configured to couple a pressure source outside of the housing to a stepped up area of the stepped piston. 8. The rotary seal assembly according to Claim 6, wherein the opening includes a diameter (D0) and a circumferential profile extending radially outward into the stepped piston, the rotary seal positioned within the circumferential profile. 9. The rotary seal assembly according to Claim 8, wherein the stepped piston includes a first diameter (D1) portion and a second greater diameter (D2) portion, and further wherein the circumferential profile is located in the first diameter (D1) portion. 10. The rotary seal assembly according to Claim 9, further comprising one or more linear dynamic seals for sealing the stepped piston relative to a housing surrounding the pressure compensation piston. 11. The rotary seal assembly according to Claim 10, wherein a first linear dynamic seal is positioned at least partially within a radially exterior surface of the first diameter (D1) portion to seal the first diameter (D1) portion relative to the housing, and further wherein a second linear dynamic seal is positioned at least partially within a radially exterior surface of the second diameter (D2) portion to seal the second diameter (D2) portion relative to the housing. 12. The rotary seal assembly according to Claim 6, wherein the rotary seal is a first rotary seal, and further including a second rotary seal positioned proximate and between an outer radial surface of the rotatable shaft and an inner radial surface of the longitudinal opening for sealing the rotatable shaft relative to the housing. 13. The rotary seal assembly according to Claim 12, wherein the circumferential profile is a first circumferential profile, and further including a second circumferential profile extending radially inward into the rotatable piston, the second rotary seal positioned within the second circumferential profile. 14. The rotary seal assembly according to Claim 12, wherein the pressure compensation piston is a first pressure compensation piston positioned in the cavity, and further including a second pressure compensation piston positioned in the cavity, the second pressure compensation piston including: a second stepped piston having a second opening extending there through for positioning the second stepped piston about the rotatable shaft; and a third rotary seal positioned along a radial surface of the second opening for sealing the second stepped piston relative to the rotatable shaft. 15. The rotary seal assembly according to Claim 6, further including a radial bearing positioned within the cavity. 16. The rotary seal assembly according to Claim 15, wherein the pressure compensation piston is positioned uphole in the cavity relative to the radial bearing. 17. The rotary seal assembly according to Claim 16, further including a thrust bearing positioned within the cavity. 18. The rotary seal assembly according to Claim 17, further comprising a second radial bearing positioned within the cavity and downhole of the thrust bearing. 19. The rotary seal assembly according to Claim 6, wherein the pressure compensation piston and the housing are rotationally fixed relative to one another and are configured to rotate relative to the rotatable shaft. 20. A well system, comprising: a wellbore located within a subterranean formation; a rotary seal assembly positioned in the wellbore via a conveyance, the rotary seal assembly including: a housing; a rotatable shaft positioned in a longitudinal opening in the housing, the housing and rotatable shaft forming a cavity there between; and a pressure compensation piston positioned in the cavity, the pressure compensation piston including: a stepped piston having an opening extending there through for positioning the stepped piston about the rotatable shaft; and a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft. |
[0030] Table 1: Example of pressure calculations with one pressure compensation piston [0031] Referring to FIG. 4, depicted is another embodiment of a rotary seal assembly 400 according to principles of the disclosure. The rotary seal assembly 400 is similar in many respects to the rotary seal assembly 300 of FIG. 3. Accordingly, like reference numbers have been used to reference similar, if not identical, features. The rotary seal assembly 400 differs, for the most part, from the rotary seal assembly 300, in that the rotary seal assembly 400 includes a second pressure compensation piston 460 positioned within the cavity 310 between the housing 315 and the rotatable shaft 320. The second pressure compensation piston 405 may be a stepped piston similar to pressure compensation piston 305 and may be configured to slide longitudinally with respect to the housing 315. In this embodiment, the second pressure compensation piston 405 may be positioned uphole of the pressure compensation piston 305. At least a first and second linear dynamic seal 430 and 435 may similarly be positioned between the second pressure compensation piston 405 and the housing 315. [0032] In some embodiments, there may be a third dynamic rotary seal 425 positioned along a radial surface of the opening of the second pressure compensation piston 405 for sealing the second pressure compensation piston 405 relative to the rotatable shaft 320. In some embodiments, the housing 315 may include a second annulus pressure port 445 therein, wherein the second annulus pressure port 445 may be configured to couple a pressure source outside of the housing 315 proximate to a stepped up area A2 of the second pressure compensation piston 405. [0033] Table 2 included herein provides an example of sample calculations showing pressure and force calculations for the rotary seal assembly 400 including a second pressure compensation piston 405. Referring to the column in Table 2 showing the combined pressures with Piston 1 + Piston 2, which is the combination of the pressure compensation piston 305 and the second pressure compensation piston 405. Table 2 illustrates how adding one or more additional pressure compensation pistons may provide further reduction of pressure differential across the first dynamic rotary seal 325 and the third rotary seal 425. Thus, whereas the pressure differential across the rotary seal 325 would have been 8.28 MPa without the stepped pressure compensation piston 305 and stepped pressure compensation piston 405, the inclusion of the first stepped pressure compensation piston 305 and second pressure compensation piston 405 reduces the pressure differential across the third rotary seal 425 to 3.10 MPa and first rotary seal 325 to 1.16 MPa. [0034] Table 2: Example of pressure calculations with a first and second pressure compensation piston:
[0035] Aspects disclosed herein include: A. Provided is a pressure compensation piston for use with a rotary seal assembly, the pressure compensation piston including: 1) a stepped piston having an opening extending there through for positioning the stepped piston about a rotatable shaft of a rotary seal assembly; and 2) a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft. B. A rotary seal assembly, the rotary seal assembly including: 1) a housing; 2) a rotatable shaft positioned in a longitudinal opening in the housing, the housing and rotatable shaft forming a cavity there between; and 3) a pressure compensation piston positioned in the cavity, the pressure compensation piston including: a) a stepped piston having an opening extending there through for positioning the stepped piston about the rotatable shaft; and b) a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft. C. A well system, the well system including: 1) a wellbore located within a subterranean formation; 2) a rotary seal assembly positioned in the wellbore via a conveyance, the rotary seal assembly including: a) a housing; b) a rotatable shaft positioned in a longitudinal opening in the housing, the housing and rotatable shaft forming a cavity there between; and c) a pressure compensation piston positioned in the cavity, the pressure compensation piston including: i) a stepped piston having an opening extending there through for positioning the stepped piston about the rotatable shaft; and ii) a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft. [0036] Aspects A, B, and C may have one or more of the following additional elements in combination: Element 1: wherein the opening includes a diameter (D 0 ) and a circumferential profile extending radially outward into the stepped piston, the rotary seal positioned within the circumferential profile. Element 2: wherein the stepped piston includes a first diameter (D 1 ) portion and a second greater diameter (D 2 ) portion, and further wherein the circumferential profile is located in the first diameter (D 1 ) portion. Element 3: further including one or more linear dynamic seals for sealing the stepped piston relative to a housing surrounding the pressure compensation piston. Element 4: wherein a first linear dynamic seal is positioned at least partially within a radially exterior surface of the first diameter (D 1 ) portion to seal the first diameter (D 1 ) portion relative to the housing, and further wherein a second linear dynamic seal is positioned at least partially within a radially exterior surface of the second diameter (D 2 ) portion to seal the second diameter (D 2 ) portion relative to the housing. Element 5: further comprising an annulus pressure port in the housing, the annulus pressure port configured to couple a pressure source outside of the housing to a stepped up area of the stepped piston. Element 6: wherein the opening includes a diameter (D 0 ) and a circumferential profile extending radially outward into the stepped piston, the rotary seal positioned within the circumferential profile. Element 7: wherein the stepped piston includes a first diameter (D 1 ) portion and a second greater diameter (D 2 ) portion, and further wherein the circumferential profile is located in the first diameter (D 1 ) portion. Element 8: further comprising one or more linear dynamic seals for sealing the stepped piston relative to a housing surrounding the pressure compensation piston. Element 9: wherein a first linear dynamic seal is positioned at least partially within a radially exterior surface of the first diameter (D 1 ) portion to seal the first diameter (D 1 ) portion relative to the housing, and further wherein a second linear dynamic seal is positioned at least partially within a radially exterior surface of the second diameter (D 2 ) portion to seal the second diameter (D 2 ) portion relative to the housing. Element 10: wherein the rotary seal is a first rotary seal, and further including a second rotary seal positioned proximate and between an outer radial surface of the rotatable shaft and an inner radial surface of the longitudinal opening for sealing the rotatable shaft relative to the housing. Element 11: wherein the circumferential profile is a first circumferential profile, and further including a second circumferential profile extending radially inward into the rotatable piston, the second rotary seal positioned within the second circumferential profile. Element 12: wherein the pressure compensation piston is a first pressure compensation piston positioned in the cavity, and further including a second pressure compensation piston positioned in the cavity, the second pressure compensation piston including a second stepped piston having a second opening extending there through for positioning the second stepped piston about the rotatable shaft, and a third rotary seal positioned along a radial surface of the second opening for sealing the second stepped piston relative to the rotatable shaft. Element 13: further including a radial bearing positioned within the cavity. Element 14: wherein the pressure compensation piston is positioned uphole in the cavity relative to the radial bearing. Element 15: further including a thrust bearing positioned within the cavity. Element 16: further comprising a second radial bearing positioned within the cavity and downhole of the thrust bearing. Element 17: wherein the pressure compensation piston and the housing are rotationally fixed relative to one another and are configured to rotate relative to the rotatable shaft. [0037] Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.
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