SEPARATE SEAL AND ANCHOR COMPONENTS

Inventors: Christopher R. Matthews-Ewald; Halit Dilber; John M. Sprott;

Jagunna Babajide; and Kent S. Meyer

FIELD OF THE INVENTION

[0001] The field of the invention is inflatable plugs and more particularly those where the sealing and anchoring are accomplished by discrete inflatable elements which can be selectively deflated for plug removal.

BACKGROUND OF THE INVENTION

[0002] Wells occasionally need to be abandoned. Sometimes the abandonment is permanent and other times it is temporary. Abandonment usually requires an isolation device such as a bridge plug. In some abandonments the plug has cement delivered on to top it. In gas wells there are regulations for the level of sealing that is required. These standards are known as V0 or V3, for example.

[0003] While inflatables have been used in subterranean locations for a long time their use is principally focused on external casing packers mostly in open hole applications where the inflatables are extended with a material that sets up such as cement and the inflatable packer is intended to stay in position permanently. One concern in the design of inflatables is the available grip against differential pressure. Another concern is to avoid trapping fluids when inflating. This issue is often addressed with a sealing element that has overlapping metallic rib segments embedded in the opposed ends of the sealing element so that the unreinforced middle section of the sealing element comes out first to displace well fluids as the inflatable continues to enlarge under increasing inflate fluid pressure. In an effort to enhance the ability of the inflatable to grip, the sealing and anchoring functions have been assumed by discrete inflatables that seal and anchor respectively. One such design is shown in the context of a permanent packer inflated with cement with separate inflatables 40 and 42 for sealing and anchoring respectively. The anchor portion 42 has one or more stiffener rings 60. The sealing element 40 has embedded ribs at each end to encourage the middle of the sealing element to come out first so that well fluids can be displaced as the seal 40 is inflated into position. While this design works for a permanent external casing packer it does not achieve the sealing degree needed for gases per the available standards that are applied particularly to very deep wells in the order of 10,000 meters or deeper.

[0004] The present invention provides discrete anchor and sealing inflatables but disposes overlapping ribs under the annular sealing element in the seal portion of the assembly. The anchor portion includes one or more stiffeners and the inflatable elements have valving systems that permit deflation so that the well can be put into service after the bridge plug and any associated cement are removed. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.

SUMMARY OF THE INVENTION

[0005] A retrievable inflatable plug system features distinct seal and anchor elements where the seal element features overlapping ribs preferably metallic and preferably overlapping. The ribs extend the substantial length of the packer and are disposed under the annularly shaped sealing element. The anchor features exposed continuous ribs extending from opposed ends with one or more stiffener rings disposed on the exposed ribs. The elements can be inflated separately or together and include valving systems to allow deflation for selective removal of the plug to put a well back into service.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a part section view with the anchor element on the downhole side;

[0007] FIG. 2 is an alternative embodiment showing the anchor element on the uphole side;

[0008] FIG. 3 is a zoomed out view of the assembly shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0009] Referring to FIGS. 2 and 3the seal element assembly 10 is shown in the downhole position relative to the anchoring element assembly 12 and the order is reversed in FIG. 3. Both assemblies are inflated through ports 14 after ball 16 is landed on seat 18. Inflation can take place at the same or at staggered times for the assemblies 10 and 12. The anchor assembly 12 features a plurality of overlapping ribs 20 that extend continuously between ends 22 and 24 and further comprise flat metallic strips of a material compatible with well fluids. One or more stiffener rings 26 are used to stiffen the ribs 20 and control the amount of flexing. The rings 26 also press against the surrounding borehole tubular that is not shown to enhance the grip of the ribs 20 that are also in contact with the same surrounding borehole tubular.

[0010] Referring to FIG. 1 it is seen that the sealing element 28 has opposed ends 29 and 31 that extend further and are bonded to end sleeves 33 and 35. The bond to each sleeve 33 and 35 is on an outer surface and an end surface as shown in FIG. 1. The sealing element 28 is also bonded to overlapping ribs 30 that extend the distance between sleeves 33 and 35. Because of this there is bonding to multiple surfaces for the sealing element 28 which tends to hold the extending portions 37 and 39 that respectively overlay sleeves 33 and 35 together to avoid popping off when inflated and subjected to differential pressure so that the standard V0 and V3 can be met with confidence.

[0011] The sealing element assembly 10 has an annularly shaped sealing element 28 that is preferably made of a single layer of material compatible with the anticipated well conditions. It can be a single layer of rubber or optionally multiple layers bonded together. As in the anchor assembly 12 there are overlapping ribs 30 that extend the full length of the sealing element 28 but are disposed preferably fully under the element 28. As an option the ribs 30 can be partially or fully embedded in the sealing element 28. As seen in FIG. 3 the arrangement of the assemblies 10 and 12 can be reversed from the FIG. 2 arrangement.

[0012] Optionally more than one sealing assembly 10 may be provided with the anchor assembly 12 positioned between seal assemblies 10 or at one end or the other. Multiples of assemblies 10 and 12 can be used in an alternating pattern or all of one kind of assembly together adjacent to the other type of assembly. The valving system associated with inflate port 14 allows subsequent deflation so that both assemblies 10 and 12 can be removed if the well is to be put back in service. Collectively, the one or more seal assemblies 10 meet the V0 or V3 standard for fluid containment in the borehole. The details regarding the VO and V3 standards are as follows: 3 ^r edition issued on April 2015 of ISO 14310:2008 (Modified), Petroleum and Natural Gas Industries— Downhole Equipment— Packers and Bridge Plugs

-V3 Acceptance Criteria - No more than 1% reduction in the maximum rated differential pressure over 15 minutes hold period, after sufficient time has been allowed for stabilization.

-V0 Acceptance Criteria - Zero bubbles of gas accumulated in a graduated cylinder over the 15 minutes hold period after sufficient time has been allowed for stabilization.

[0013] .The seal assemblies 10 can have one end such as 32 fixed while the opposite end is movably mounted to facilitate movement of the sealing element 28 toward the surrounding tubular string in the borehole. The sealing element 28 may have an assembly inside diameter that is smaller than the outside diameter of the ribs 30 or the element could be formed onto the ribs 30.

[0014] The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: