ARRANGEMENT

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Application No.13/764153, filed on February 11, 2013, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Cementing of a liner or a casing in a well is done to, among other things, prevent flow in an annular space between the liner or casing and the open borehole. It is common to perform several cementing operations within a single deep well. When additional drilling is required after a cementing operation has been completed, the cementing plugs, shoe and cement located at the bottom of the section of well just cemented need to be drilled through before the drill bit can begin drilling into the earth formation again. Drilling through a plug can damage or dull a drill bit, can generate undesirable debris within the wellbore and can delay drilling progress in the earth formation. Systems and methods that alleviate the foregoing concerns are well received in the industry.

BRIEF DESCRIPTION

[0003] Disclosed herein is a removable plug arrangement. The arrangement includes at least one plug configured to lead or follow a hardenable material that is pumped through a tubular, the plug has one or more portions made of a material configured to weaken when exposed to an activation fluid.

[0004] Further disclosed herein is a method of removing a plug arrangement. The method includes exposing one or more portions of at least one cementing plug to an activation fluid capable of weakening the one or more portions, weakening the one or more portions, and drilling or milling through the weakened one or more portions.

[0005] Further disclosed herein is a removable plug arrangement. The arrangement includes a volume of hardenable material, and at least one plug configured to lead or follow the volume of hardenable material that is pumped through a tubular, the plug has one or more portions made of a material configured to weaken in response to being exposed to an activation fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

[0007] FIG. 1 depicts a cross sectional view of a removable plug arrangement disclosed herein;

[0008] FIG. 2 depicts a partial cross sectional view of an alternate removable plug arrangement disclosed herein in a first position;

[0009] FIG. 3 depicts a cross sectional view of the alternate removable plug arrangement of FIG. 2 in a second position;

[0010] FIG. 4 depicts a cross sectional view of the alternate removable plug arrangement of FIG. 2 in a third position; and

[0011] FIG. 5 depicts a partial cross sectional view of the alternate removable plug arrangement of FIG. 2.

DETAILED DESCRIPTION

[0012] A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

[0013] Referring to Figure 1, an embodiment of a removable plug arrangement is illustrated at 10. The arrangement 10 includes a single plug 14A or 14B, although alternate embodiments can include more than one of the plugs 14 as will be disclosed with reference to additional Figures herein. The plug 14 can be used to lead or to follow a hardenable material 18, illustrated herein as cement, being pumped through a tubular 22 such as a casing, liner or drill string, for example. The plug 14 in the illustrated embodiment is shown following cement 18. The plug 14 includes a portion 26, shown as a core of the plug 14 that is made of a material configured to weaken when exposed to an activation fluid. The plug 14 also includes a seal 30, made of a flexible material, such as an elastomer, for example, to allow the seal 30 to deformingly sealingly engage with walls 36 of the tubular 22 while moving therethrough.

[0014] The foregoing arrangement 10 allows an operator to clear the tubular 22 of cement 18 when finishing the pumping of the cement 18. This is accomplished by pumping the plug 14 following the cement 18, through the tubular 22 while sealing the plug 14 to the walls 36. The cement 18 remains separated from displacement fluid 40 on an opposing side of the plug 14 by the plug 14 itself. This separation prevents dilution and contamination of the cement 18 during the pumping operation. The plug 14 can be configured to engage with a landing device 44 (see Figure 2) such as a landing collar, for example, positioned at a selected location within the tubular 22. An activation fluid, which causes dissolution of the portion 26, can then be pumped to expose the portion 26 of the plug 14 thereto to weaken the portion 26 thereby facilitating its removal via a drilling or milling process, for example. The weakening of the portion 26 prior to removal of the plug 14 can simplify and expedite the process and lessen chances of generating undesirable contamination from residual parts of the plug 14 residing within the tubular 22. The portion 26 may be configured to weaken significantly after being exposed to the activation fluid in about a few hours to about a few days. Additionally, the weakening can include substantially dissolving the portion 26.

[0015] Some embodiments of the arrangement 10, include a bore 52 formed through the seal 30 to assure the portion 26 is exposed to the activation fluid. Without the bore 52, activation fluid would be prevented from coming into direct contact with the portion 26 when pumped thereagainst due to the seal 30 blocking such exposure. The bore 52 can extend a significant depth into the portion 26 to increase surface area of the portion 26 that is exposable to the activation fluid to increase a rate of dissolution of the portion 26 and to cause more uniform weakening of the portion 26. Alternatively, the bore 52 could be post- drilled into the plug 14 only at such time exposure to the activation fluid is desired. It should also be noted that activation fluid could be employed as the displacement fluid 40 with either alternative of the plug 14 (i.e. pre-bored or post-drilled). In the case wherein the plug 14 is pre-bored, exposure of the portion 26 begins as soon as the displacement/activation fluid 40 begins urging the plug 14 through the tubular 22. Consequently, the weakening of the portion 26 is timed (based on the chemical make-up of the portion and the

displacement/activation fluid 40) to prevent over-weakening of the portion 26 until the cementing operation has been completed.

[0016] In some embodiments of the removable plug arrangement the portion 26 is manufactured from a high strength controlled electrolytic metallic material and is degradable in response to exposure to an activation fluid such as brine, acid, an aqueous fluid or combinations of one or more of these. A variety of suitable materials and their methods of manufacture are described in United States Patent Publication No. 2011/0135953 (Xu et al), that is hereby incorporated by reference in its entirety.

[0017] Referring to Figures 2-4, an alternate embodiment of a removable plug arrangement is illustrated at 110. The arrangement 110 includes two of the plugs 14, designated in this embodiment as 14A and 14B. Additionally the arrangement 110 includes two plugs 114A and 114B that are sealingly receptive to the two plugs 14A and 14B respectively in a nesting arrangement. The plugs 114A and 114B have a port 116 that is sealingly receptive to the plugs 14A and 14B. It is also possible for a cementing operation to employ just one each of 14A or 14B and 114A or 114B. In such a system the pair of the plugs 14A and 114A or 14B and 114B may be employed to follow the cement 18 to thereby maintain separation of the displacement fluid 40 from the cement 18. Determination of which of the plugs 14A, 14B, 114A, 114B to use depends upon the specifics of the operation.

[0018] The nesting of the plugs 14A and 14B into the plugs 114A and 114B allow an operator to maintain separation of the cement 18 from the displacement fluid 40 with one of the plugs 14 A, 14B while pumping through a smaller diameter tubular, and then to continue maintaining separation of the cement 18 from the displacement fluid 40 while pumping the nested plugs 14 A, 14B, 114 A, 114B through a larger diameter tubular. To do so an operator positions the plug 114A, for example, in the larger tubular downstream of a smaller tubular through which the plug 14A is first pumped. The plug 114A is initially open to flow through the bore 52. When the plug 14A engages with the plug 114A it seals the bore 52 thereby preventing additional flow therethrough. As such, the pair of plugs 14A with 114A or 14B with 114B can be used to lead or to follow the cement 18.

[0019] In Figure 2 the pair of plugs 14A and 114A have been pumped ahead of the cement 18 and have landed on a landing collar 44 positioned within a tubular 124. The landing collar 44 forms an annular flow path 128 that allows the cement 18 to flow past the plugs 14A and 114A seated thereat to allow the cementing process to continue as is illustrated in Figure 3. In Figure 4 the second set of plugs 14B and 114B have landed at the first pair of plugs 14A and 114A with the displacement fluid 40 positioned upstream thereof. This designates the end of the cementing operation.

[0020] Referring to Figure 5, the two plugs 114A and 114B are shown without the plugs 14A and 14B positioned within the port 116 for purposes of simplicity. Each of the plugs 114A and 114B are made of seals 130A, 130B and portions 126A, 126B, respectively. Similar to the seal 30, the seals 130A, 130B are made of a flexible material, such as an elastomer, for example, to allow the seals 130A, 130B to deformingly sealingly engage with walls of the tubular 124 while moving therethrough. The portions 126A, 126B are made of one or more parts that are (similar to the portion 26) in that they are configured to weaken when exposed to activation fluid. The parts that make up the portions 126A, 126B can vary as is shown by the variation in parts that make up the portion 126 A of the plug 114A compared to the parts that make up the portion 126B of the plug 114B. The portion 126 A includes a nose 132, a body plug 134, a bottom insert 138, a bottom sleeve 142, a bottom collet 146, a connector 150 and a slip 154. The portion 126B includes a retaining collet 158, a body plug 162, a top insert 166, a top sleeve 170 and a top collet 174. In this embodiment, all of the parts that make up the portions 126A and 126B are made of a weakenable material such as that described above. The plugs 114A, 114B are configured such that all of the parts that define the portions 126A, 126B are exposed to activation fluid once activation fluid is positioned within the ports 116. As such, weakening of all parts of the portions 126 A, 126B is initiated substantially simultaneously.

[0021] While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.