MIXED ELEMENT SWELL PACKER SYSTEM AND METHOD

A technique facilitates use of a swellable packer or packers which may be disposed along completion equipment of a well string. Each packer comprises a packer frame and a plurality of swellable elements formed of materials which swell in different types of fluids. The plurality of swellable elements may comprise a first swellable element mounted on the packer frame and swellable in a first type of fluid. A second swellable element also may be mounted on the packer frame proximate the first swellable element and swellable in a second type of fluid which is different from the first type of fluid. Additionally, a portion of an alternate path system may extend through the swellable elements to facilitate a gravel packing operation.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority benefit of MY Application No. PI2021003799, filed Jul. 2, 2021, the entirety of which is incorporated by reference herein and should be considered part of this specification.

BACKGROUND

In many oil and gas well applications, a wellbore is drilled into the earth and through a reservoir of the desired fluid, e.g. oil and/or gas. The wellbore may subsequently be completed with appropriate completion equipment comprising screens, packers, and other equipment selected to facilitate production of the desired fluids from the reservoir. In some applications, the completion equipment may comprise alternate path systems which facilitate gravel packing of the annulus between the completion equipment and the surrounding wellbore wall. The gravel packing is used to establish a gravel pack sufficient to filter out particulates from the well fluid as it flows from the reservoir, into the wellbore, and into the completion equipment for production to a desired collection location. Installation of the gravel pack may occur along a number of well zones which are isolated via packers positioned along the completion equipment at a desired spacing. At an appropriate time, the packers are actuated to form a seal with the surrounding wellbore wall, thus isolating the desired well zones along the wellbore.

SUMMARY

In general, a system and methodology facilitate improved actuation and use of packers disposed along completion equipment by utilizing mixed swelling elements. According to an embodiment, a packer or packers may be disposed along the completion equipment of a well string to provide seals along a borehole at desired locations. Each packer comprises a packer frame and a plurality of swellable elements formed of materials which swell in different types of fluids. For example, the plurality of swellable elements may comprise a first swellable element mounted on the packer frame and swellable in a first type of fluid. Additionally, a second swellable element is mounted on the packer frame proximate the first swellable element and swellable in a second type of fluid which is different from the first type of fluid, e.g. oil versus water. A portion of an alternate path system may extend through the swellable elements to facilitate a gravel packing operation.

DETAILED DESCRIPTION

The disclosure herein generally involves a system and methodology which facilitate improved actuation and use of packers. According to an embodiment, a packer or packers may be disposed along completion equipment of a well string to provide seals along a borehole, e.g. a wellbore, at desired locations. The packers are constructed as swellable packers which have a mixed element swellable section to enable the desired swelling and sealing when exposed to different types of fluids.

For example, each packer may comprise a packer frame and a plurality of swellable elements formed of materials which swell in different types of fluids. The plurality of swellable elements may comprise two swellable elements or a greater number of swellable elements. By way of example, the mixed swellable elements may comprise a first swellable element mounted on the packer frame and swellable in a first type of fluid. In this example, a second swellable element also may be mounted on the packer frame at a position proximate the first swellable element and swellable in a second type of fluid which is different from the first type of fluid. For example, the first swellable element may swell in the presence of water while the second swellable element swells in the presence of oil. However, the swellable elements may be selected to undergo the desired swelling and sealing along the wellbore when exposed to other types of fluids. Additionally, a portion of an alternate path system may extend through the swellable elements to facilitate a gravel packing operation.

The individual packers may be constructed in a variety of sizes and configurations depending on the parameters of a given application. By way of example, the swellable elements may be placed adjacent to each other to form the desired mixed element structure and then molded and bonded over shunt tubes of an alternate path system. The mixed element structure provides a user flexibility with respect to use of a variety of fluids, e.g. hydrocarbon or water-based fluids, to achieve the desired swelling in a single shunted packer. Swelling of a single element when reacting with the corresponding fluid is sufficient to swell the packer to the maximum outside diameter so as to form sufficient contact and sealing against the surrounding borehole wall, thus providing the desired mechanical integrity and pressure barrier along the borehole, e.g. wellbore. Depending on the application, the packer may be used to form a seal against casing, against an open hole wall, or against another type of surrounding borehole wall.

The sequence and arrangement of the swellable elements, e.g. two or more swellable elements, may vary and can be selected according to the type of well and the type of naturally occurring or pumped down fluids available in a given operation. In some operations, naturally occurring fluids may be used to provide the desired swelling of the swellable element or elements. In other operations, however, selected fluids may be circulated downhole and into contact with the swellable elements to achieve the desired swelling of at least one of the swellable elements. Additionally, the swellable elements may be formed from suitable elastomers or other swellable materials. The swellable elements may be solid and continuous body type elements; solid and continuous incised body type elements; incised or segmented body type elements; or other suitable constructions.

When fully swelled, the outside diameter of an individual swellable element is able to act as a mechanical barrier for diverting fluid and gravel pack slurry through, for example, shunt tubes. The individual swelled element also can serve as a pressure barrier to provide zonal isolation between adjacent well zones along the wellbore to prevent unwanted communication and co-mingling of fluids between zones. In some applications, gravel packing may be performed through alternate path systems, e.g. through shunt tubes, after swelling of the desired swellable packers. In other applications, however, the gravel packing operation may be performed first while leaving the desired swellable packers to swell to their target outside diameters once exposed to certain fluids following the gravel packing operation.

Referring generally toFIG.1, an example of a well string20is illustrated as deployed in a borehole22, e.g. a wellbore. In this example, the well string20comprises a completion system24disposed downhole in borehole22for use in gravel packing operations, production operations, and/or other well related operations. The completion system24may comprise a variety of downhole components, including production tubing26, an alternate path system28deployed along the production tubing26, and a plurality of swellable packers30spaced along the production tubing26. It should be noted the completion system24may comprise a wide variety of additional or other components to facilitate the desired downhole operations. For example, the completion system24may comprise screens, filters, inflow control devices, shrouds, sensors, and various other types of components. Many of these components are selected and arranged to facilitate production of a desired well fluid, e.g. oil and/or gas, from a surrounding formation32.

The production tubing26may be formed from a plurality of base pipe joints34connected by suitable couplers36(seeFIGS.2and3). The alternate path system28may be routed along the production tubing26and through the swellable packers30so as to ensure uniform gravel packing in the well zones disposed along the wellbore22. As illustrated, various gravel packing techniques may be used to establish a gravel pack38disposed in an annulus40between the completion system24and a surrounding wall42forming wellbore22. Depending on the well application, the surrounding wall42may be, for example, the interior of well casing or the open wellbore wall formed during drilling of the wellbore.

InFIG.1, the swellable packers30are illustrated as swelled to their enlarged, target outside diameter. In this swelled state, each swellable packer30establishes a firm, sealing engagement with the surrounding wellbore wall42so as to create a desired mechanical and/or pressure barrier between well zones/regions along the wellbore22, e.g. along annulus40. As described in greater detail below, the swellable packers30may comprise mixed elements which individually expand in the presence of a predetermined fluid to provide the desired engagement with the surrounding wellbore wall42. In the embodiment ofFIG.1, three swellable packers30are illustrated however the completion system24may comprise various numbers of swellable packers30, including a single swellable packer30, two swellable packers30, or three or more swellable packers30.

Referring generally toFIG.2, an example of one of the swellable packers30is illustrated. In this example, the swellable packer30comprises a packer frame44disposed about the production tubing26. The packer frame44may have a variety of configurations for supporting a mixed swellable element system46. According to the embodiment illustrated, the packer frame44comprises end rings48having openings50to receive the alternate path system28therethrough. For example, the alternate path system28may comprise shunt tubes52for carrying gravel slurry to desired gravel packing regions along the wellbore22. The shunt tube or tubes52may be routed through the openings50of end rings48along the exterior of production tubing26.

By way of example, the mixed swellable element system46may comprise a plurality of swellable elements54which are located longitudinally between the end rings48and over the shunt tubes52. In some embodiments, the swellable elements54are swellable elastomeric elements which may be wrapped around the shunt tubes52and the production tubing26and then cured and bonded in place. However, a variety of mounting techniques may be used for mounting the swellable elements54at the desired position relative to packer frame44. The swellable elements54are unique elements that may be positioned proximate to each other, e.g. contiguous with each other between the end rings48.

The specific material of individual swellable elements54is selected to uniquely respond based on its exposure to a specific fluid or fluids. The combination of different individual swellable elements54in a single packer30enables swelling in response to exposure to different fluids. For example, an individual swellable element (or elements)54may swell in the presence of water while another individual swellable element (or elements)54of the same swellable packer30swells in the presence of a different fluid such as oil.

It should be noted that swelling in the presence of water is intended to mean swelling in the presence of water-based fluids and such fluids may include constituents other than simply water. For example, the water may include salts, acids, minerals, other treatment chemicals, or other constituents that do not prevent water induced swelling of the corresponding swellable element(s)54. Similarly, swelling in the presence of oil is intended to mean swelling in the presence of oil-based fluids and such fluids may include constituents other than simply oil. For example, the oil may include gases and other constituents that do not prevent oil induced swelling of the corresponding swellable element(s)54.

The number of swellable elements54in a given packer30may vary. For purposes of explanation, the packer30illustrated inFIG.2comprises two swellable elements54positioned adjacent each other between end rings48of packer frame44. The two swellable elements54comprise a first swellable element56which swells in the presence of a first fluid, e.g. water, and a second swellable element58which swells in the presence of a second fluid, e.g. oil. Accordingly, the second swellable element58swells in the presence of a different type of fluid than the fluid which causes swelling of the first swellable element56.

However, the swelling of either of the swellable elements56,58is sufficient to create a seal with the surrounding wellbore wall42which has the desired mechanical and pressure integrity. As a result, each swellable packer30ensures creation of the desired barrier in the presence of different types of fluids and thus enhances the reliability of completion system24during a given operation.

In the example illustrated, the unique fluids are in the form of water and oil for causing swelling of swellable elements56,58, respectively. However, the materials used to form the different swellable elements56,58may be selected to respond to a variety of different types of fluid. In some embodiments, individual swellable elements54may be selected to swell in response to various treatment chemicals pumped downhole to facilitate, for example, a gravel packing operation and/or production operation.

Many types of materials are swellable in the presence of water and may be used to form swellable element56in at least some downhole applications. Examples of such materials include elastomeric materials such as tetrafluoroethylene/propylene copolymer (TFE/P), vinyl acetate/acrylate copolymer, carboxymethylcellulose type polymer, isobutylene/maleic anhydride copolymer, and a variety of other elastomeric materials which may be selected according to the parameters of a given well application. Other examples may include various composite materials or non-elastomeric materials such as swelling clay material.

Similarly, there are many types of materials which are swellable in the presence of oil and may be used to form swellable element58in at least some downhole applications. Examples of such materials include chlorinated butyl rubber, polyurethane rubber, butyl rubber, various silicone rubbers, and a variety of other oil-swellable rubbers, sulfonated polyethylene, ethylene/propylene/diene terpolymer, and a variety of other materials. Additionally, various combinations of these materials and other composite and/or non-elastomeric materials may sufficiently swell in the presence of oil and have sufficient sealing and structural characteristics to form swellable element58. Various materials which swell when placed in contact with other types of fluids also may be used in the construction of swellable element56and/or swellable element58.

As illustrated inFIG.3, the arrangement of first and second swellable elements56,58may be reversed or otherwise changed. Some embodiments may utilize additional materials which respond to additional types of unique fluids. Furthermore, some embodiments may utilize greater numbers of the swellable elements54to ensure the desired contact and sealing with the surrounding wall42. In the examples illustrated inFIGS.2and3, each swellable element56,58has sufficient length to establish the desired seal with the desired mechanical and pressure integrity along annulus40. In some environments, the longitudinal length of each swellable element56,58may be 5 feet or more.

Referring generally toFIG.4, an operational example is illustrated via a flow chart. In this example, the well application involves use of alternate path system28to establish a gravel pack along completion system26deployed in wellbore22. Initially, the number of zones or sections of the wellbore22and the fluid types that will be encountered or utilized in the operation may be determined. This enables selection of the number of swell packers30and the types of swell elements54to be utilized. Because each swell packer30employs a mixture of the swell elements54, the successful swelling/expansion of the swell packers30can be assured even when there is less specific knowledge with respect to the fluids that will be entering wellbore22.

As illustrated, the completion system26is initially assembled with the desired components which may include a variety of bottom hole assemblies, alternate path system28, and the desired number of swellable packers30, as indicated by block60. The packers30are constructed with the appropriate swellable elements54and internal shunt tubes52. The completion system26is then deployed downhole into wellbore22via a workstring, as indicated by block62. Subsequently, a suitable space out procedure may be implemented to help set the completion system26at a target depth in the wellbore22, as indicated by block64.

Once the completion system26is properly positioned, pre-gravel pack preparations may be performed, as indicated by block66. This allows the gravel pack treatment/installation to be performed to establish the desired gravel pack38, as indicated by block68. In some applications, an optional filter cake breaker may be pumped downhole to remove filter cake, as indicated by block70. At this stage, the workstring may be released and pulled out of hole, as indicated by block72. The completion system26with the shunted swellable packers30remains downhole to allow exposure of the swellable elements54to fluids which will cause one or more of the swellable elements54to swell and expand into sealing contact with the surrounding wellbore wall42, as indicated by block74. Because individual swellable elements54uniquely respond to different fluids, e.g. oil or water, at least one of the swellable elements54is assured of expanding into the desired sealing contact.

Referring generally toFIG.5, another operational example is illustrated via a flow chart. In this example, the well application again involves use of alternate path system28to establish a gravel pack along completion system26deployed in wellbore22. Initially, the number of zones or sections of the wellbore22are determined and the types of swelling fluid to be circulated and displaced into the well (or encountered in the well) for a given operation also may be determined. This determination enables selection of the number of swell packers30and the types of swell elements54to be utilized. Because each swell packer30utilizes a mixture of the swell elements54, the successful swelling/expansion of the swell packers30can be assured even when there are different types of fluids that may be used to cause the desired swelling.

As illustrated, the completion system26is initially assembled with the desired components which may include a variety of bottom hole assemblies, alternate path system28, and the desired number of swellable packers30, as indicated by block76. The packers30are constructed with the appropriate swellable elements54and internal shunt tubes52. The completion system26is then deployed downhole into wellbore22via a workstring, as indicated by block78. Subsequently, a suitable space out procedure may be implemented to help set the completion system26at a target depth in the wellbore22, as indicated by block80.

Once the completion system26is properly positioned, at least one of the appropriate swelling fluids may be pumped or otherwise delivered downhole to, for example, spot swell the desired swellable packers30, as indicated by block82. Sufficient time is provided to enable sufficient swelling of the packer elements54so as to achieve the desired mechanical barrier and/or pressure isolation function of the subject swellable packers30. Subsequently, pre-gravel pack preparations may be performed, as indicated by block84. This allows the gravel pack treatment/installation to be performed to establish the desired gravel pack38, as indicated by block86. In some applications, an optional filter cake breaker may be pumped downhole to remove filter cake, as indicated by block88. At this stage, the workstring may be released and pulled out of hole, as indicated by block90. The completion system26with the shunted swellable packers30remains downhole to facilitate subsequent production operations.

Depending on the parameters of a given operation and the environment in which such operation is conducted, the number of swellable packers30utilized along the wellbore/borehole22may vary substantially. Additionally, the number and arrangement of swellable elements54on each packer30may vary and may be selected to swell in the presence of a variety of dissimilar fluids. The type of packer frame44and the techniques for mounting both the alternate path components as well as the swellable elements54about the packer frame44may vary. In some embodiments, the swellable elements54may be connected or otherwise placed in contact with each other. In other embodiments, however, the swellable elements54may be uniquely positioned along each individual swellable packer30. Similarly, the completion system26may have a wide range of configurations and components to help achieve desired gravel packing operations, production operations, and/or other downhole operations.