This invention relates generally to methods and apparatus for cementing a casing in a wellbore, and more specifically is directed to methods and apparatus for utilizing float equipment inside casing used to drill a wellbore.
There are a variety of known methods for drilling wellbores to intersect with one or more hydrocarbon-producing formations for the production of oil and/or gas. One known procedure, and an increasingly common procedure for drilling a wellbore utilizes the casing string that will be cemented into the wellbore as the drill string. When a wellbore is drilled utilizing casing as the drill string, the wellbore is drilled to a desired depth, and the casing is typically pulled upwardly a distance from the bottom of the drilled wellbore. The drill bit on the lower end of the casing is then blown off using an explosive charge on a wireline, or is disconnected from the casing by other means known in the art.
Once the drill bit has been removed from the lower end of the casing, mud or other circulating fluids may be circulated through the casing. A bottom cementing plug can then be displaced into the casing ahead of the cement. The bottom cementing plug is allowed to pass through the open lower end of the casing and cement passes around the lower end of the casing upwardly into the annulus between the casing and the wellbore. Once the desired amount of cement has been displaced into the casing, a top cementing plug is placed in the casing behind the trailing edge of the cement. The top plug and the cement therebelow are urged downwardly in the casing by drilling mud or other known displacement fluids. Once the desired amount of cement has been placed in the annulus between the casing and the wellbore to cement the casing in the wellbore, which may occur either before or after the top cementing plug exits the casing, flow of the displacement fluid is stopped. Pressure is maintained utilizing a valve system at the surface, typically in connection with a plug container. Prior to conducting any further operations or procedures, it is generally necessary to wait several hours to insure that the cement is adequately set up prior to removing surface equipment, such as the plug container, and then reassembling the wellhead. Although such procedures exist for drilling with casing and then cementing the casing in a wellbore, the time loss is significant and costly. Thus, an improved apparatus and method for drilling with casing and cementing casing in a wellbore is needed.
The present invention provides an improved method and apparatus for cementing casing in a wellbore. The apparatus includes a casing with a drill bit attached to the lower end thereof. The wellbore is drilled with the casing as the drill string. Once the wellbore is drilled, the casing is pulled upwardly to lift the drill bit from the bottom of the wellbore. The drill bit is then disconnected from the casing by any manner known in the art.
The apparatus further includes a check valve placed in the casing after the drill bit is disconnected from the casing. The check valve is preferably a part of a float apparatus and more preferably is part of float shoe which includes an outer case with the check valve connected therein. The check valve includes a valve body connected in the outer case. The valve body defines a valve seat. The check valve also includes a valve poppet which includes a valve element that is engageable with the valve seat.
The float shoe is connected to a packer apparatus which is lowered into the casing to a desired location in the casing. The packer apparatus can be lowered into the casing on a wireline or by other means known in the art. Once the packer apparatus is lowered into the casing, it is set in the casing so that it will hold the packer apparatus and the float shoe in the casing. The wireline is then removed and cementing operations can begin. A bottom cementing plug may be placed in the casing ahead of the leading edge of the cement. The bottom cementing plug will land on the upper end of the packer apparatus and a rupturable diaphragm will burst allowing cement to flow through the bottom cementing plug, the packer apparatus and the float apparatus. Cement will be displaced into the annulus between the casing and the wellbore. Once a sufficient amount of cement has been placed in the casing, a top cementing plug may be placed in the casing behind the trailing edge of the cement and will be urged downwardly with a displacement fluid. The top cementing plug will land on the bottom cementing plug. Reassembly of the wellhead at the surface can begin since the float apparatus will prevent the back flow of cement into the casing.
Referring now to the drawings and more particularly to
The apparatus 38 of the present invention, which may be also referred to as a float system 38, is shown in
In
Packer apparatus 42 includes slip wedges 70 which may be referred to as upper slip wedge 72 and lower slip wedge 74. Upper slip wedge 72 is positioned adjacent retaining ring 68 at the upper end 64 of packer element assembly 60. In similar fashion, lower slip wedge 74 is positioned adjacent retaining ring 68 at the lower end 66 of packer element assembly 60. Upper slip wedge 72 is attached to packer mandrel 58 with a shear pin 76. Lower slip wedge 74 is attached to packer mandrel 58 with a shear pin 78.
Packer apparatus 42 likewise includes slip segments 80 which may be referred to as upper lip segments 82 and lower slip segments 84. Upper slip segments 82 are connected with an upper retainer portion 86 thereof to a setting ring assembly 88 which may be referred to as a lock ring assembly 88. Lock ring assembly 88 includes a lock ring housing 87 and a lock ring 89. Lower slip segments 84 are connected with a lower retainer portion 90 thereof to coupling 50 which as set forth herein is threadedly connected to packer mandrel 58.
Float shoe 48 is connected to lower end 59 of packer mandrel 58 with coupling 50, which is preferably a steel coupling 50. Float shoe 48 includes an outer case or outer sleeve 91. A check valve 92 is connected in outer case 91 and in the embodiment shown is threadedly connected therein. Check valve 92 includes a valve body 94 and a valve poppet 96. Valve poppet 96 includes a valve stem 98 having a head portion 100 defined at the upper end 102 thereof. A valve element 104 is connected to a lower end 106 of valve stem 98 and is preferably threadedly connected to valve stem 98. Valve stem 98 is disposed in a valve guide 105 which extends inwardly from and may be integrally formed or connected with valve body 94. A spring 107 is positioned between valve guide 105 and head portion 100 and urges valve stem 98, and thus valve element 104, upwardly into engagement with a valve seat 108 defined on valve body 94. An elastomeric seal, which may be referred to as a lip seal 110 may be affixed to the valve element 104 to provide sealing engagement between valve element 104 and valve seat 108.
The operation of apparatus 38 is apparent from the drawings. As shown in
Once apparatus 38 has been lowered into casing 15, packer apparatus 42 is set using wireline setting device 40 by any manner known in the art, and thus is moved into the position shown in
As shown in
As is apparent from the drawings, because packer apparatus 42 has an uninterrupted bore 69, full bore unrestricted flow through packer apparatus 42 is achievable. A sufficient volume of cement for primary cementing operations is therefore available with apparatus 38 of the present invention. Typical packers known in the art have valves or other mechanisms so that a sufficient volume of cement flow for cementing casing in a wellbore is not attainable. For example, Halliburton's EZ DrillĀ® squeeze packer has a valve configuration therein such that while the packer is adequate for use in squeeze cementing, it should not be utilized for primary cementing purposes since the necessary volume and rate of cement flow for primary cementing cannot be achieved.
Once top cementing plug 118 has landed, pressure in the well can be bled off and monitored for a relatively short period of time, for example five minutes. Equipment at the surface, such as plug containers, can then be removed and other steps taken to reassemble the wellhead at the surface. This is a great improvement over the prior art methods of drilling with casing which require a several-hour waiting period before the wellhead can be reassembled.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description, they are not intended to be exhaustive or to limit the invention to the precise forms disclosed but obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, and thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.
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Number | Date | Country | |
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20040118560 A1 | Jun 2004 | US |