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.
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.
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, U.S. Pat. No. 6,009,951, is shown in the context of a permanent packer inflated with cement with separate inflatables, as shown in that patent, 40 and 42 for sealing and anchoring respectively. The anchor portion 42, in that patent, 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.
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.
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.
Referring to
Referring to
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
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. As shown by double headed arrow 15, 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. The abandoning occurs after inflation as shown in arrow 15 when expansion occurs. Removing happens after deflation as shown by arrow 15. Arrow 17 further illustrates the abandoning by movement to the right in conjunction with inflating and expanding the seal and anchor while movement to the left illustrates deflating and then removal by movement to the right. Collectively, the one or more seal assemblies 10 meet the V0 or V3 standard for fluid containment in the borehole. The details regarding the V0 and V3 standards are as follows: 3rd edition issued on April 2015 of ISO 14310:2008 (Modified),
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.
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:
Number | Name | Date | Kind |
---|---|---|---|
4253676 | Baker | Mar 1981 | A |
4403660 | Coone | Sep 1983 | A |
5613555 | Sorem | Mar 1997 | A |
6009951 | Coronado et al. | Jan 2000 | A |
6131656 | Jani | Oct 2000 | A |
6779601 | Wilson | Aug 2004 | B2 |
8336634 | Eatwell | Dec 2012 | B2 |
8905149 | Bailey | Dec 2014 | B2 |