Patent ID: 12209476

All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

FIG.1shows a downhole sealing assembly1providing a seal in a borehole2between a first face3and a second face4of a completion component50having an axial extension L along the borehole2. The downhole sealing assembly1comprises an annular sealing element5arranged on the second face4and having a base part6, a first annular flange7and a second annular flange8. Both the first annular flange7and the second annular flange8extend from the base part6in a first direction along the axial extension L, forming a cavity9between the first and second annular flanges7,8. The first annular flange7is arranged closest to the first face3and has a projection10abutting the second face4. The annular sealing element5is formed as a coherent ring. The annular sealing element5may in another embodiment have a slit along the axial extension L so that it is easier to mount. The downhole sealing assembly1further comprises a metal ring-shaped element11arranged in the cavity9and having a first ring end12closest to the base part6and a second ring end14opposite the first ring end12. As shown inFIG.2, the metal ring-shaped element11has a first ring face15being concave towards the first annular flange7for receiving the first annular flange7when the downhole sealing assembly1is arranged between the first and second faces3,4. Thus, the first ring face15forms a first indentation16, such as a curvature, from the first ring end12to the second ring end14. The downhole sealing assembly1further comprises a first spring element17arranged in the cavity9between the first annular flange7and the metal ring-shaped element11in order to press the first annular flange7to abut against the second face4. When the downhole sealing assembly1is arranged between the first and second faces3,4, the annular sealing element5is squeezed, and the first annular flange7is pressed into the first indentation16, stretching the first spring element17, whereupon the inherent spring force in the first spring element17will force the first annular flange7radially outwards towards the second face4, thus providing an enhanced seal. Thus, the downhole sealing assembly1is inFIG.1shown in a slightly compressed and tensioned condition, and inFIG.2the downhole sealing assembly1is shown in a relaxed condition.

As shown inFIGS.1and2, the first spring element17is plate- and tubular-shaped. Thus, the first spring element17is ring-shaped. The first spring element17may in one aspect have a slit (not shown) along the axial extension L so that the first spring element17can be slightly expanded when mounted in the cavity. The cavity9has an extension extending from the base part6to an end of the first annular flange7, and the first spring element17has the same extension as the cavity9. The first indentation16has a first indentation length LI1along the axial extension L, and the projection10of the first annular flange7has a first projection length LP1(shown inFIG.3) which is shorter than the first indentation length W. The first spring element17has a first element length LE1along the axial extension L. The metal ring-shaped element11has a second length L2along the axial extension L, and the first element length LE1is substantially the same as the second length. The metal ring-shaped element11may in one aspect have a slit (not shown) along the axial extension L so that the metal ring-shaped element11can be slightly expanded when mounted. The base part6has a first thickness t1along the axial extension L. The first annular flange7has a second thickness t2perpendicular to the axial extension L, and the second annular flange8has a third thickness t3perpendicular to the axial extension L, the first thickness t1being greater than the second thickness t2and the third thickness t3. The base part6has a first height hi perpendicular to the axial extension L in a radial direction, and the annular sealing element5has a first length L1along the axial extension L which is greater than the first height hi. The metal ring-shaped element11has a second length L2along the axial extension L that is shorter than the first length L1. The first ring face15faces the first annular flange7, and a second ring face21faces the second annular flange8and is straight. Thus, inFIG.2one of the first ring face15and the second ring face21is substantially straight, and the other of the first ring face15and the second ring face21has an indentation such as a curvature, i.e. the metal ring-shaped element11is concave at one side.

InFIG.3, the metal ring-shaped element11has the second ring face21forming a second indentation22for receiving the second annular flange8. The second ring face21is concave towards the second annular flange8for receiving the second annular flange8so that the second ring face21forms the second indentation22, in the form of a curvature, from the first ring end12to the second ring end14. The second ring face21faces the second annular flange8, and the curvature is configured to receive the second annular flange8when the downhole sealing assembly1is compressed between the first face3and the second face4of the completion component50. The downhole sealing assembly1further comprises a third spring element23between the second ring face21and the second annular flange8so as to keep the second annular flange8in sealing abutment to the second face4of the completion component50. During compression of the downhole sealing assembly1, the second annular flange8is pressed into the second indentation22, stretching the third spring element23, whereupon the inherent spring force in the third spring element23will force the second annular flange8radially outwards towards the second face4, thus providing an enhanced seal. The second annular flange8is shorter than the first annular flange7along the axial extension L and also shorter than the metal ring-shaped element11so that the second indentation22may more easily receive the second annular flange8. By having both a first indentation16and a second indentation22, the downhole sealing assembly1has a double sealing flexibility in that during compression both the first annular flange7and the second annular flange8can be received in an indentation, and due to the spring elements both annular flanges7,8are pressed radially outwards after compression, providing an enhanced seal against both the first face3and the second face4.

InFIG.4, the second annular flange8comprises a projection18projecting away from the first annular flange7. In a cross-sectional view, the first annular flange7has a U-shape forming a lip flange19for abutting the second face4. The lip flange19has a tip32facing towards the base part6. The downhole sealing assembly1further comprises a second spring element20arranged between the lip flange19and the first annular flange7so as to keep the first annular flange7in its intended extended position irrespectively of the compression of the lip flange19so that the lip flange19can function optimally as intended without being affected by any odd position of the first annular flange7. The second spring element20overlaps the base part6and abuts the bend of the first annular flange7, i.e. the “bottom” of the U-shape, in order to keep the first annular flange7fully extended. The second spring element20is ring-shaped. The first spring element17may in one aspect not shown have a slit in order to be more suited for mounting. The downhole sealing assembly1may be pressurised from both sides, and when the pressure is greater on the left side, the pressure forces the lip flange19radially outwards, thus sealing even better to the second face4, and when the pressure is greater on the right side, the whole first annular flange7, including the lip flange19, is pressed radially outwards, thus enhancing the ability to seal to the second face4. The pressure from the right also forces the second annular flange8towards the second face4. As can be seen inFIG.4, the projection10of the first annular flange7is part of the lip flange19.

The second indentation22inFIG.5has a second indentation length LI2along the axial extension L. The second indentation length LI2is equal to the first indentation length W. The second annular flange8is shorter than the first annular flange7along the axial extension L. The downhole sealing assembly1further comprises a metal ring24having a flange33overlapping the base part6of the downhole sealing assembly1and a body part34abutting the base part6, forming a back-up to the annular sealing element5. The flange has a flange length LF along the axial extension L being the same or greater than the first thickness t1of the base part6so as to support the base part6in order to maintain the base of the annular sealing element5.

InFIG.6, the projection18of the second annular flange8has a second projection length LP2which is shorter than the second indentation length LI2, shown inFIG.5. The second annular flange8inFIG.6is shorter than the second annular flange8ofFIG.5so that the second annular flange8having the projection18inFIG.6may be received in the second indentation22during compression of the downhole sealing assembly1. The first indentation16is slightly greater than the second indentation22in that the second annular flange8comprises less material than the first annular flange7including the lip flange19.

As shown inFIG.7, the downhole sealing assembly1further comprises a fourth spring element31abutting the second spring element20so as to strengthen the second spring element20in order to keep the first annular flange7in its intended extended position irrespectively of the compression of the lip flange19so that the lip flange19can function optimally as intended without being affected by any odd position of the first annular flange7.

By having such design of the downhole sealing assembly1as shown inFIGS.1-12, the annular sealing element5can be made of Polytetrafluoroethylene (PTFE) so that the downhole sealing assembly1is capable of withstanding high temperatures above 225° C. while still functioning as intended. Known seals using elastomer or similar conventional sealing materials cannot withstand such high temperatures and still function properly as the material strength of such materials weakens significantly at such high temperatures. The spring elements17,20are made of spring metal or spring steel, and the metal ring-shaped element11is made of metal proven for use in an oil or gas well. The materials of the downhole sealing assembly1are suited for geothermal wells as all materials in the downhole sealing assembly1can withstand the high temperatures in such geothermal wells without losing their sealing ability. The downhole sealing assembly1is thus able to function at temperatures above 220° C. and to withstand a pressure difference above 1400 PSI.

FIG.7shows a downhole sealing unit30comprising a first downhole sealing assembly1,1aand a second downhole sealing assembly1,1bcorresponding to the downhole sealing assembly1previously described, wherein the base part6of the first downhole sealing assembly1,1afaces the base part6of the second downhole sealing assembly1,1bso that the first annular flange7of the first downhole sealing assembly1extends from the base part6and away from the first annular flange7of the second downhole sealing assembly1, lb. Thus, the first downhole sealing assembly1,1aand the second downhole sealing assembly1,1bare arranged back-to-back in that the base parts6are closer to each other than the first annular flanges7are to each other. Because the downhole sealing assemblies1,1a,1bare arranged back-to-back, the downhole sealing unit30can better withstand high pressure from one side, also when sliding past an opening in the first face3of the completion component50in that when one of the first downhole sealing assembly1,1aand the second downhole sealing assembly1,1bis passing the opening and thus not sealing optimally, the other downhole sealing assembly is able to provide sufficient sealing.

The downhole sealing unit30further comprises the metal ring24having a T-shape in cross-section and being arranged between the first downhole sealing assembly1,1aand the second downhole sealing assembly1,1b, abutting the base parts6of the first and second downhole sealing assemblies1,1a,1b. The metal ring24comprises two flanges33,33A,33B, each flange overlapping the base part6of the first downhole sealing assembly1,1aand the second downhole sealing assembly1,1b, respectively, and the body part34being arranged between the first downhole sealing assembly1,1aand the second downhole sealing assembly1, lb. The metal ring24has the two flanges, i.e. a first projecting flange33A overlapping the base part6of the first downhole sealing assembly1,1aalong the axial extension L and a second projecting flange33B overlapping the base part6of the second downhole sealing assembly1,1balong the axial extension L. The metal ring24thus forms a back-up to both the first downhole sealing assembly1,1aand the second downhole sealing assembly1, lb. The flanges33,33A,33B have a thickness that is substantially thicker than the lip flange19. The metal ring24has at least one through-bore25extending radially in a direction perpendicular to the axial extension L for providing fluid communication. The through-bore25serves the purpose of equalising the pressure across the seal when one downhole sealing assembly1,1a,1bis sliding past an opening in the second face4of the completion component50; the pressure is quickly equalised through the through-bore25for optimising the sealing ability of the other downhole sealing assembly1,1a,1b. This is due to the fact that when the first downhole sealing assembly1,1ais passing the opening and thus not sealing optimally, then the second downhole sealing assembly1,1bis able to provide sufficient sealing as the pressure is equalised to also affect the second annular flange8of the second downhole sealing assembly1, lb. The metal ring24may have several through-bores25as shown inFIG.8. Even though not shown, the annular sealing element5is made of PTFE and other parts of metal, where the spring elements17,20are made of spring steel. A ring or tubular may be arranged in the through-bore25.

The completion component50is shown inFIG.9forming part of a downhole system100and comprising a first component part51having the first face3and a second component part52having the second face4facing the first face3. The first component part51and the second component part52are slidable in relation to each other. The completion component50further comprises the downhole sealing assembly1,1a,1bas mentioned above for arrangement between the first face3and the second face4. InFIG.9, the completion component50is a sliding sleeve50A or a telescopic joint50B, and inFIGS.10A-Cthe completion component50is a telescopic joint50B. The sliding sleeve50A ofFIG.9has a sliding sleeve part55which is the second component part52, and the sliding sleeve part55is slidable in relation to an opening56in a tubular section58which is the first component part51, the tubular section58being mountable as part of a well tubular metal structure90. The tubular section58comprises a groove57in which the sliding sleeve part55is slidably arranged. In another aspect, the sliding sleeve part55may be sliding along the inner face of the tubular section58without being arranged in the groove57.

The telescopic joint50B ofFIGS.10A-Cis mountable as part of the well tubular metal structure90, and the first component part51comprises a first part61overlapping a second part62of the second component part52so that when the temperature in the well changes, and the well tubular metal structure90either decreases or increases in length, this decrease or increase in length is accumulated by the first part61and the second part62as they are able to slide in relation to each other, thus accumulating the variations in length of the well tubular metal structure.FIG.10Ashows the telescopic joint50B in its initial position where it is ready for an increase in the length of the well tubular metal structure90and thus strokes to its “stroked-out” position as shown inFIG.10C, or for a decrease in the length of the well tubular metal structure90and thus strokes to its “stroked-in” position as shown inFIG.10B. The telescopic joint50B comprises inFIGS.10A-Cone downhole sealing assembly1, but may in another embodiment comprise a plurality of downhole sealing assemblies1,1a,1barranged in between the first part61and the second part62for sealing against the first face3and the second face4. The second component part52comprises an outer projection63projecting radially outwards from the second face4and having an outer diameter larger than an inner diameter of the first component part51so as to hinder the first component part51from sliding past the outer projection63. The first component part51comprises an inner projection64projecting radially inwards from the first face3, and the first part61has an inner diameter smaller than an outer diameter of the outer projection63of the second component part52so as to hinder the first component part51from sliding past the inner projection64.

As shown inFIG.9, the downhole system100comprises the completion component50mounted as part of the well tubular metal structure90and two annular barriers80. Each annular barrier80comprises a tubular metal part85having an aperture86and an expandable metal sleeve81surrounding the tubular metal part85, and each end83,84of the expandable metal sleeve81is connected with the tubular metal part85, forming an expandable space82when fluid enters the aperture for expanding the expandable metal sleeve81until the expandable metal sleeve81abuts a wall of the borehole2.

FIG.11shows a cross-sectional view of another downhole sealing unit30comprising a first downhole sealing assembly1,1aand a second downhole sealing assembly1,1b, corresponding to the downhole sealing assembly1previously described, wherein the base part6of the first downhole sealing assembly1,1afaces the base part6of the second downhole sealing assembly1,1b, so that the first annular flange7of the first downhole sealing assembly1extends from the base part6and away from the first annular flange7of the second downhole sealing assembly1, lb. Thus, the first downhole sealing assembly1,1aand the second downhole sealing assembly1,1bare arranged back-to-back in that the base parts6are closer to each other than the first annular flanges7are to each other. The downhole sealing unit30further comprises the metal ring-shaped element11which is formed of two abutting ring-shaped elements11a,11bbeing a first metal ring-shaped element11aand a second metal ring-shaped element11b. Furthermore, the first ring face15forming the first indentation16is formed partly of the first metal ring-shaped element11aand partly of the second metal ring-shaped element11bfor forming the cavity9.

Furthermore, the metal ring24is formed of two abutting rings24a,24bbeing a first metal ring24aand a second metal ring24b, so that the abutting first metal ring24aand second metal ring24bhave a T-shaped cross-section which is formed of a stem part53and projecting flanges33,54a,54b, where each of the projecting flanges33,54a,54boverlaps the first downhole sealing assembly1,1aand the second downhole sealing assembly1,1b, respectively. Thus, each abutting ring24a,24bhas an L-shaped cross-section which, when the ring is abutting, forms a T-shaped cross-section. The downhole sealing unit30further comprises at least one through-bore25which intersects both of the two abutting rings24a,24b, so that part of the through-bore25forms a groove25ain one of the two abutting rings, and the other part of the through-bore25forms a groove25bin the other of the two abutting rings, which grooves together form the through-bore.

The downhole sealing unit30further comprises a first element41having a first inclined face42abutting a second inclined face43of the metal ring24. By having a first element41with the inclined face42configured to slide in relation to the second inclined face43, the first element41can slide and move towards the second face4when the pressure acts on the downhole sealing assembly1, squeezing the downhole sealing assembly1so that the base part6presses onto the first element41. By being able to move towards the second face4, the first element41keeps forming a sufficient back-up to the downhole sealing assembly1and provides a pre-tensioning force on the downhole sealing assembly1so that when the pressure releases, the first element41is able to press the downhole sealing assembly1to return to its less pressurised condition. The first element41having the first inclined face42abuts the second inclined face43on a first side44of the metal ring24, and the downhole sealing unit30further comprises a second element45having a first inclined face46abutting a second inclined face47on a second side48of the metal ring24. The first element41and the second element45may be of PEEK (Polyether ether ketone) or PAEK (Polyaryletherketone) or similar material, or metal.

FIG.12shows a cross-sectional view of another downhole sealing unit30comprising a first downhole sealing assembly1,1aand a second downhole sealing assembly1,1b, corresponding to the downhole sealing assembly1previously described. The first downhole sealing assembly1,1aabuts the second downhole sealing assembly1,1b, so that the first annular flange7of the first downhole sealing assembly1aextends towards and faces the first annular flange7of the second downhole sealing assembly1b. The first downhole sealing assembly1,1aand the second downhole sealing assembly1bare thus arranged to abut and face each other with no separate element arranged therebetween. Thus, the metal ring-shaped element11of the first downhole sealing assembly1,1aabuts the metal ring-shaped element11of the first downhole sealing assembly1a.

The downhole sealing unit30further comprises at least one through-bore25intersecting both metal ring-shaped elements11, so that part of the through-bore25forms a groove25ain one of the metal ring-shaped elements11, and the other part of the through-bore25forms a groove25bin the other of the metal ring-shaped elements11, which grooves together form the through-bore.

The downhole sealing unit30further comprises a first metal ring24aand a second metal ring24b. The first metal ring24ais arranged to abut the base part6of the first downhole sealing assembly1a, and the second metal ring24bis arranged to abut the base part6of the second downhole sealing assembly1b. The first metal ring24ahas an L-shape in cross-section and is formed of a stem part53and one projecting flange54a, where the one projecting flange54aoverlaps the base part6of the first downhole sealing assembly1a. The second metal ring24bhas an L-shaped cross-section which is formed of a stem part53and one projecting flange54b, where the one projecting flange54boverlaps the base part6of the second downhole sealing assembly1b.

The downhole sealing unit30ofFIG.12further comprises a first element41having a first inclined face42abutting a second inclined face43of the first metal ring24aand a second element45having a first inclined face46abutting a second inclined face47of the second metal ring24b.

By “fluid” or “well fluid” is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By “gas” is meant any kind of gas composition present in a well, completion or open hole, and by “oil” is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil and water fluids may thus all comprise other elements or substances than gas, oil and/or water, respectively.

By “annular barrier” is meant an annular barrier comprising a tubular metal part mounted as part of the well tubular metal structure and an expandable metal sleeve surrounding and connected to the tubular metal part defining an annular barrier space.

By “casing” or “well tubular metal structure” is meant any kind of pipe, tubing, tubular, liner, string, etc., used downhole in relation to oil or natural gas production.

Although the invention has been described above in connection with preferred embodiments of the invention, it will be evident to a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.