Patent Grant
9845656
In connection with the completion of oil and gas wells, it is frequently necessary to utilize packers in both open and cased boreholes. The walls of the well or casing are plugged or packed from time to time for a number of reasons. As shown in
In some situations, operators may prefer to utilize a comparatively long sealing element on the packer's 16. In these instances, as the sealing element is compressed longitudinally by a piston, friction and other forces combine to cause the sealing element to bunch up or otherwise bind near the piston. As a result, the longer sealing element does not uniformly compress in the longitudinal direction and by extension does not expand uniformly in the radial direction. The lack of uniform expansion tends to prevent the packer 16 from forming a seal that meets the operator's expectations, thereby defeating the purpose of utilizing a longer sealing element
Therefore, a significant need exists for a packer that is able to utilize an extended length sealing element.
A packer, plug, or other downhole tool has an extended-length, compressible sealing element. The sealing element is reinforced with a rigid member that causes the sealing element to deform in a controlled manner when the sealing element is longitudinally compressed. The rigid member reinforces certain portions of the sealing element. Yet, the rigid member has one or more areas of decreased rigidity that decreases the reinforcement for certain portions of the sealing element.
By controlling the deformation of the sealing element with the rigid member, unwanted deformation is prevented. Such unwanted deformation is usually caused by friction between the sealing element, the tool's mandrel, and the casing or wellbore. In the past, the unwanted deformation has typically caused longer sealing elements to bunch up on the end of the element closest to the mechanism causing the sealing element to be longitudinally compressed. Additionally, such unwanted deformation has also tended to limit the effectiveness of the seal created between the tool's mandrel and the casing or wellbore by the sealing element. Thus, previous sealing elements on tools, such as packers, have been limited in length in order to retain an effective seal.
In an embodiment of the present disclosure, a rigid member is bonded to the elastomeric sealing element. The rigid member can be a cylinder or can be a plurality of slats. The rigid sealing member has thinner and thicker portions that control the deformation of both the rigid member and the adjacent sealing element with respect to the rest of the sealing element during longitudinal compression of the sealing element. As the rigid member and the elastomer deform, the longitudinal compression causes a first portion of the sealing element to bend outward while the adjacent portion may bend inwards. The first portion bending outwards may tend to seal more against the wellbore wall or the casing while the adjacent portion may tend to seal more against the mandrel. The reverse may also be true depending on the circumstances.
The rigid member can be metallic, non-metallic, or a combination of metallic and non-metallic. In some embodiments, the rigid member can be configured to bend at certain locations, or if desired the rigid member can be configured to break at certain points. In other embodiments, the rigid member can have an accordion-like, corrugated, or spring structure. In this case, this type of rigid member can bend over its length in a single direction, such as longitudinally, while resisting radial deformation.
In another embodiment, an accordion-like, corrugated, or spring-like rigid member may be used to control the expansion of the elastomeric sealing element. By utilizing a structure, such as a spring, the deformation of the sealing element may be locally limited until the entire sealing element has at least partially deformed. The circumferential hoops in the structure, such as a spring, would tend to limit the initial radial expansion of the bonded elastomeric sealing element while allowing the sealing element to be longitudinally compressed.
In another embodiment, a sealing element for use in a wellbore may have an inner elastomeric element, an outer elastomeric element, and a rigid member disposed between them. The rigid member has at least one area of decreased rigidity, such as from a notch of reduced thickness, from a difference in corrugated structure, from a difference in spring strength, and from other differences of the rigid member as disclosed herein.
Although the rigid member may be located between the inner elastomeric element and the outer elastomeric element, the inner elastomeric element and the outer elastomeric element may actually be attached, bonded, molded, or formed to one another. The rigid member may be affixed to the inner elastomeric element and the outer elastomeric element by an adhesive or by bonding, such as during an extrusion process. In some instances, the rigid member may be at least two rigid members, and typically the two rigid members may run parallel to one another along the longitudinal length of the sealing element.
In another embodiment, a sealing element for use in a wellbore may have an elastomeric element and a rigid member having at least one area of decreased rigidity. The rigid member may be attached to the elastomeric element by an adhesive or by bonding such as during an extrusion or molding process. Typically, the rigid member is embedded in the elastomeric element. In some instances, the rigid member may have at least two rigid members, and the rigid members may be linked by a band, such as a circumferential band.
In another embodiment, a sealing element for use in a wellbore may have an elastomeric element and at least one spring. The spring may be embedded in the element or may be attached to the elastomeric element by an adhesive or by bonding, such as during an extrusion or molding process. Typically, the spring limits the initial radial expansion of the elastomeric element when the spring and the elastomeric element are longitudinally compressed. The spring can vary in strength or rigidity along its length. In some instances, more than one spring, such as a first spring and a second spring, may be used end-to-end in a single sealing element. In some instances, the first spring has a first spring strength and the second spring has a second spring strength.
In another embodiment, an apparatus, such as a plug or a packer for use in a wellbore, may have a sealing element having a first elastomeric portion and a second elastomeric portion. The first portion has a first compressive strength and the second portion has a second compressive strength. In some instances the first elastomeric portion and the second elastomeric portions may be connected. In other instances the first elastomeric portion and the second elastomeric portions may be separate.
To seal a downhole tool in a wellbore, the downhole tool is deployed in the wellbore. The compressible element is then sealed in the wellbore by radially expanding the compressible element in response longitudinal compression of the compressible element. This deforms the rigid member. Ultimately, sealing of at least a portion of the compressible element is controlled with the rigid member by deforming at least one area of reduced rigidity on the rigid member adjacent the portion the compressible element different from other portions of the compressible element.
As used herein, the terms such as lower, downhole, downward, upper, uphole, and upward are merely provided for understanding. Additionally, the terms packer and plug may be used interchangeably.
The description that follows includes exemplary apparatus, methods, techniques, and instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.
The sealing element 100 has an initial diameter to allow the packer 50 to be run into a well and has a second, radially-larger size when compressed to seal against the wellbore. When the packer 50 is set downhole, the mandrel 60 is held in place and force is applied longitudinally to the sealing element 100 by the setting mechanism 68, which in this example is a hydraulic piston mechanism.
For example, the mechanism 68 is activated by a build-up of hydraulic pressure in a chamber of the mechanism 68 through a port 64 in the mandrel 60. In turn, the piston mechanism 68 pushes against the end of the sealing element 100 to compress the sealing element 100 longitudinally. As it is compressed, the sealing element 100 expands radially outward to engage the surrounding surface, which can be an open or cased hole. Although the tool 50 is shown as being hydraulically actuated, other types of mechanisms 68 known in the art can be used on the tool 50 including, mechanical, hydro-mechanical, and electrical mechanisms for compressing the sealing element 100.
As briefly depicted in
The element's elastomeric member 110 can be attached, bonded, molded, or formed on the mandrel 60 and the rigid member 150 in any suitable fashion. For instance, the element's elastomeric member 110 can be comprised of separate layers 120 and 122 of the same or different elastomeric material. The rigid member 150 may be affixed between the inner elastomeric layer 120 and the outer elastomeric layer 122 by an adhesive or by bonding, such as during an extrusion or molding process. Alternatively, the rigid member 150 may be molded or embedded directly into the elastomeric material of the member 110.
In any event, the member 110 has an outer elastomeric portion or layer 120 disposed external to an inner elastomeric layer 122. Each of the layers 120 and 122 may be separate elements or sleeves disposed, molded, or formed on the rigid member 150. Alternatively, the inner and outer elastomeric layers 120 and 122 may be integrally molded or formed portions of the same underlying element on the rigid member 150.
In one embodiment, the rigid member 150 is a cylindrical sleeve disposed about the mandrel 60. In another embodiment, the rigid member 150 is comprised of several longitudinal strips disposed parallel to one another along the axis of the sealing element 100 and the mandrel 60. In yet another embodiment, the rigid member 150 is a cage structure having a combination of cylindrical bands disposed around the mandrel 60 and having a number of longitudinal members spaced around the mandrel 60.
The rigid member 150 is disposed as an intermediate layer in the elastomeric member 110. The rigid member 150 may be affixed to one or both of the push rings (not shown), or the ends of the members 150 may simply abut adjacent the rings. As shown, the rigid member 150 has areas of different rigidity or thicknesses along its length. In the embodiment depicted, thinned regions or notches 160a-c are alternatingly facing opposing sides of the rigid member 150. For instance, first notches 160a, 106c face inward toward the mandrel 60, while second notches 160b face outward towards the wellbore 10. The layers 120 and 122 can fill in the various notches 160a-c with material, depending on how the layers 120 and 122 are formed on the rigid member 150 and mandrel 60.
As shown in the detail of
In general, the depths (d), widths (w), and spacings (s) of the notches 160a-c can be the same or different, but the characteristics of the notches 160a-c can be configured to govern how the rigid member 150 will bend and the sealing element 100 will deform when compressed. In particular, the depths (d), widths (w), and spacings (s) of the notches 160a-c determine what direction and when the rigid member 150 will deform at particular locations.
Moving the notch sidewalls 164a-b in towards one another as well as increasing the angle of the notch sidewalls 164a-b can determine how far the rigid member 150 will initially deform. The depth (d) of each notch 160a-b can determine the order in which the various notches 160a-c will deflect. For instance, shallower notches 160a leave a thicker bridge of material on the rigid member 150. Such a thicker bridge will allow this portion of the rigid member 150 around the shallower notch 160a to deform later than a deeper notch 160c having a thinner bridge of material. Additionally, the location of a given notch 160a-c in either side of the rigid member 150 determines in which direction the rigid member 150 will deform. A notch 160b that faces the wellbore 10 tends to cause the rigid member 150 to deform away from the wellbore 10, while a notch 160a, 160c facing the mandrel 60 tends to cause the rigid member 150 to deform away from the mandrel 60.
The notches 160 may be reversed. Furthermore, thinner notches 160 can be positioned in the middle, on the outer portion, or to one side of the rigid member 150 depending of the desired outcome of the element's compression. Additionally, deeper notches 160 can be positioned on the top end of the rigid member 150 and shallower on the bottom end, or vice versa.
Because the sealing element 100 has an extended length, the timing of how it deforms as it is longitudinally compressed on the mandrel 60 can be controlled by the rigid member 150 so the element 100 does not prematurely buckle, crease, fold, or otherwise expand improperly against the surrounding wall. In this particular example having five notches 160a-c along the length of the element 100, the notches 160a-c are symmetrically arranged with a center notch 160c, two intermediate notches 160b, and two end notches 160a. The depth (d), width (w), angles, etc. of the center notch 160c are configured to force the center portion of the element 100 to deform and set first. This is not strictly necessary because there may be implementations in which the center portion sets after one or both of the ends.
In this implementation, however, the intermediate notches 160b spaced outside of the center notch 160c are configured with widths (w) and depths (d) to set later at a delayed timing from the center notch 160c. By first setting the center of the element 100 followed and then setting outward along the length of the element 100, fluid can escape from the annulus between the element 100 and the wellbore 10 during setting procedures. Finally, the end notches 160a spaced toward the ends of the element 100 are configured to set even later during the overall setting process.
The arrangement here is symmetrical and includes five notches 160a-c. Other configurations can be used with more or less notches 160, and such an alternating arrangement can be repeated along the length of the sealing element 100. Accordingly, the number of notches 160 may vary depending on the length of the element 100 and the desired number of timed seal points.
Each rigid member 250 has notches 260. As noted previously, each notch 260 may have a width, depth, notch bridge thickness, distance between the notch sidewalls, and notch sidewall angles that are configured different or similar to one another depending upon the desired deformation characteristics. Additionally, the notches 260 can be arranged to face inward and/or outward as desired. Each notch 260 tends to cause the rigid members 250 to deflect radially inward or outward in an organized way configured for a particular implementation, as disclosed herein.
Here, the rigid members 250 are a plurality of longitudinal strips or slats disposed parallel to one another along the longitudinal axis and around the circumference of the elastomeric element 210. The members 250 may be affixed to one or both of the push rings 204 and 206, or the ends of the members 250 may simply abut adjacent the rings 204 and 206. Again, the rigid members 250 can be composed of any suitable material, including metal, plastic, or an elastomer more rigid than the overall sealing element 200.
For its part, the rigid cage 330 has rings or bands 332 with a plurality of rigid strips or slats 350 running parallel to one another along the length of the cage 330. The rings 332 and the rigid slats 350 are attached to one another and are embedded in the radially inward and outward elastomeric layers 320 and 322 (depicted in dashed lines). The bands 332 can be affixed to or abut against the push rings 304 and 306. Although the bands 332 are shown at the ends of the cage 330 one or more bands can also be used at intermediate locations of the cage 330 between the ends.
Each rigid slat 350 has notches 360. As before, each notch 360 may have a different notch bridge thickness, a different distance between the notch sidewalls, different notch sidewall angles, face inward or outward, and other features depending upon the desired deformation characteristics.
The spring 450 varies in rigidity by varying in pitch from the push rings 404 and 406 as it progresses longitudinally along the elastomeric sealing element 410. In some instances, the spring 450 can vary in pitch from the first push ring 404 towards the second push ring 406 in any combination that meets the operator's requirements. The spring's 450 variation in pitch can be seen as a different in the distance between the spring's hoops, such as the different distances (w1) and (w2) depicted in
The circumferential hoops formed by the spring 450 as it circumferentially surrounds the mandrel 402 can tend to limit the initial radial expansion of the sealing element 400 while allowing the sealing element 400 to be longitudinally compressed. The differences in distances between the hoops tend to allow the sealing element 400 to radially expand at certain location to an extent greater than where the spring's 450 hoops are closer together. In certain instances, it may be desirable to utilize an accordion-like structure that does not vary in pitch but tends to limit the initial radial expansion of the elastomeric sealing element 400 to a uniform amount.
The springs 550a-c are embedded in the elastomeric member 510. For example, the springs 550a-c can be attached to a radially inward elastomeric layer 520 and to a radially outward elastomeric layer 522. In
Each spring 550a-c varies in strength or the force exerted as the spring 550a-c compresses. In
When the sealing element 500 is set, the weakest spring (e.g., 550c) will tend to longitudinally compress first, thereby causing the sealing element 510 adjacent to the spring 550c to longitudinally compress and thereby radially expand. By varying the strength of each spring 550a-c, the timing of the radial expansion of each portion of the sealing element 500 may be controlled by the operator.
When the packer and thus the sealing element 600 is set, the more flexible sections of the rigid member 650 tend to longitudinally compress first, thereby causing the elastomeric sealing element 600 to radially expand. By varying the flexibility, the timing of the radial expansion of the sealing element 600 may be controlled by the operator.
Finally,
Each section 750a-n of the sealing element 700 varies in compressive strength or the force required to compress each section 750a-n. In a variation of this embodiment, the longitudinally separate sections 750a-n of elastomer could be a single elastomeric member, in which the elastomeric compounds differ over the element's length, thereby providing variations in the compressive strength of the sealing element 700 over its length.
In
When the packer and thus the sealing element 700 is set, the weakest elastomeric sealing section (e.g., 750n) tends to longitudinally compress first, thereby causing the elastomeric sealing element 700 to radially expand. By varying the compressive strength of each elastomeric sealing section 750a-n, the timing of the radial expansion of each portion of the sealing element 700 may be controlled by the operator.
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.
In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.
This application claims the benefit of U.S. Provisional Appl. Nos. 61/774,727, filed 8 Mar. 2013, and 61/776,561, filed 11 Mar. 2013, which are incorporated herein by reference.
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