Patent Application
20110220356
The present invention relates generally to casing valves for use in the casing of a well, and more particularly, but not by way of limitation, to cementing tools constructed for placement in a well casing.
In the drilling of deep wells, it is often desirable to cement the casing in the wellbore in separate stages, beginning at the bottom of the well and working upward.
This process is achieved by placing cementing tools, which are primarily valved ports, in the casing or between joints of casing at one or more locations in the wellbore, flowing cement through the bottom of the casing, up the annulus to the lowest cementing tool, closing off the bottom, opening the cementing tool, and then flowing cement through the cementing tool up the annulus to the next upper stage and repeating this process until all stages of cementing the well are completed.
Cementing tools are shown, for example, in U.S. Pat. Nos. 5,038,862, 5,314,015, 5,526,878 and 3,768,556. Cementing tools often utilize sealing elements to seal between the tool and the wellbore or well casing prior to displacing cement into the well through the tool. For example, many such tools use inflatable packers to seal against the well. Oftentimes, however, inflatable packers have a limited flow area to accommodate the weighted solid laden inflation fluid and do not fully inflate. The result is that the inflatable packer will not hold as much hydraulic pressure as desired. It may be necessary in such situations to wait until the cement below the tool sets up, which is a time-consuming, and therefore costly process. There is a continuing need for stage cementing tools that can be reliably set in the well, to provide for immediate cementing of casing above the tool, with no need to wait for cement therebelow to harden.
A cementing tool for cementing a casing in a well comprises an inner mandrel and an outer mandrel disposed thereabout. An annular space is defined between the inner and outer mandrels. The inner mandrel defines a central flow passage and has at least one fluid port through a wall thereof. At least one sealing element and preferably a plurality of sealing elements are affixed to the outer mandrel. An opening sleeve detachably connected in the inner mandrel is movable from a closed position in which the opening sleeve covers the at least one fluid port to an open position in which the at least one fluid port is uncovered. The opening sleeve may be moved for example by a plug dropped through the casing used to lower the cementing tool into the well. Fluid pressure communicated through the at least one fluid port from the central flow passage into the annular space will cause the outer mandrel to radially expand, and preferably to plastically deform radially outwardly so that the at least one sealing element engages a previously installed casing in the well.
An expansion cone is positioned in the annular space between the inner and outer mandrel. The fluid communicated through the fluid port will force the expansion cone through the annular space. The expansion cone has a width greater than a width of a first portion of the annular space so that the outer mandrel will radially expand and plastically deform to engage the well. Because the outer mandrel plastically deforms it will maintain a sealing engagement with the well and will create a hydraulic seal such that cementing thereabove can occur. The cement flowed through the central flow passage, the fluid port and the annular space will pass through an upper end of the annular space and will fill an annulus between the casing used to lower the cementing tool in the well and the previously installed casing. The cementing process can occur prior to the time the cement utilized to cement a casing in the wellbore below the previously installed casing hardens. Cement will pass through an upper end of the annular space after it pushes or expels the expansion cone through the upper end thereof.
The method of cementing may therefore comprise lowering a cementing tool into the well on a casing and plastically deforming a portion of the tool so that it engages a previously installed casing in the well. The method further comprises pumping cement through the cementing tool into an annulus between the previously installed casing and the casing used to lower the cementing tool in the well. The plastically deforming step may comprise pumping fluid through an annular space defined between the inner mandrel and the outer mandrel to urge an expansion cone disposed in the annular space through a first portion of the annular space. The plastically deforming step will occur after a casing portion attached to the lower end of the cementing tool is cemented in the well.
As shown in
Referring now to
Inner mandrel 36 has upper end 42 adapted to be connected to a casing. For example, upper end 42 may be threaded so that a coupling 43 may be attached thereto which will then connect to upper portion 32 of casing 30. Lower end 44 of inner mandrel 36 is likewise adapted to be connected to a casing. For example, lower end 44 may have a thread on an outer surface thereof to connect to lower portion 34 of casing 30. It is understood that lower portion 34 may have a float collar or float shoe or other arrangement thereon whereby cement will pass through a lower end of lower portion 34 and into the annulus between wellbore 15 and lower portion 34. Cement will be displaced therethrough until a sufficient amount of cement is in the annulus and has filled the annulus to a location above annular space 40.
Mandrel 36 comprises upper portion 46 which may be referred to as the upper inner mandrel 46. Upper mandrel 46 has outer surface 47 and inner surface 49. Upper inner mandrel 46 is a generally cylindrical tube having upper end 42 which is the upper end of inner mandrel 36. Inner mandrel 36 comprises lower portion, or lower inner mandrel 48 having lower end 44. Lower inner mandrel 48 may also be referred to as a housing 48 to which sleeves utilized in the operation of cementing tool 25 are connected. Outer surface 47 defines an outer diameter 50 of upper inner mandrel 46. Inner surface 49 defines inner diameter 51. A lower end 52 of upper inner mandrel 46 is connected to an upper end 54 of lower inner mandrel 48.
A fluid port 56, which may be referred to as cementing port 56, is defined through inner mandrel 36 and preferably is defined through lower inner mandrel 48. In the embodiment disclosed, there are a plurality of fluid ports 56 defined through inner mandrel 36. Fluid ports 56, seen in
An opening sleeve 66 is disposed, and preferably detachably connected in mandrel 36 and more specifically in lower inner mandrel 48. Likewise, an operating sleeve 68 is detachably connected in lower inner mandrel 48. A closing sleeve 70 is disposed in annular space 40 about lower inner mandrel 48. Lower inner mandrel 48 has operating slots 72 defined therein. A plurality of connectors 74 operably connect operating sleeve 68 with closing sleeve 70 so that downward movement of operating sleeve 72 will cause closing sleeve 70 to move downwardly.
Outer mandrel 38 has upper end 76 and lower end 78. A connecting sub 80 having threads on an outer surface 82 thereof and likewise on an inner surface 84 thereof connects outer mandrel 38 to inner mandrel 36 at the lower end 78 of outer mandrel 36. Connecting sub 80 may have a relief port 86 with a relief plug 88 inserted therein. Relief plug 88 may be removed to allow the release of fluid in annular space 40. A debris plug 90 is inserted in annular space 40 at the upper end 76 of outer mandrel 38 and closes off an upper end of the annular space 40.
Outer mandrel 38 has upper portion 92 and lower portion 94. Upper portion 92 defines an inner diameter 93. A transition or transition portion 96 extends between upper and lower or first and second portions 92 and 94. Outer mandrel 38 has an outer surface 98. Outer surface 98 comprises an outer surface 100 on the upper portion 92 of outer mandrel 38 and an outer surface 102 on the lower portion 94 thereof. In the run-in position shown in
At least one and preferably a plurality of sealing elements 104 are disposed about outer mandrel 38. As shown in
Each of sealing elements 104 has an upper end 110 and a lower end 112, and are mounted to a sealing portion 114 of outer mandrel 38. Sealing portion 114 may have a top ring 116 and a bottom ring 118 at the upper and lower ends 110 and 112 of sealing element 104. Top and bottom rings 116 and 118 may have sharp points that extend radially outwardly from outer surface 102. Sealing portion 114 may also include grooves 120 in outer surface 100 to assist in mounting sealing elements 104. Top and bottom rings 116 and 118 are preferably integrally fabricated with outer mandrel 38 and in the expanded position shown in
Annular space 40 has upper end 120 in which debris plug 90 is placed and has lower end 122. Annular space 40 comprises upper portion 124 and lower portion 126. Upper portion 124 has a width 128 prior to the plastic deformation of upper portion 92 of outer mandrel 38. A width 130 is defined by and between the lower portion 126 of annular space 40 and upper inner mandrel 46. An expansion cone 132 which may also be referred to as expansion wedge 132 is disposed about inner mandrel 36 and in the embodiment shown is disposed about upper inner mandrel 46. Expansion cone 132 has a leading edge 134 and angles radially outwardly therefrom to an outermost diameter 136. An inner surface 140 of expansion cone 132 engages outer surface 47 of upper inner mandrel 46. A groove 142 is defined in inner surface 140 and has a sealing ring which may be for example an O-ring 144 disposed therein so that expansion cone 132 sealingly engages upper inner mandrel 46.
The width 146 of expansion cone 132 at outermost diameter 136 is greater than the width 128 of the upper portion 124 of annular space 40 prior to plastic deformation of upper portion 92 of outer mandrel 38. Thus, in the run-in position outer diameter 136 is greater than the inner diameter 93 of upper portion 92 of outer mandrel 38. A biasing member, or spring 150 is disposed in annulus space 40 about inner mandrel 36. Spring 150 has an upper end 152 and a lower end 154. Upper end 152 engages expansion cone 132 and urges expansion cone 132 towards the first or upper portion 124 of annular space 40. Lower end 154 of spring 50 engages an upper end 155 of lower inner mandrel 48. Upper end 155 defines a shoulder 156 to provide an engagement surface for spring 150.
Expansion cone 132 in the position shown in
The operation of cementing tool 25 is as follows. Tool 25 is lowered into the well 10 on casing 30. It will be understood that the lower end of casing 30 (not shown) will have float equipment such as a float collar or float shoe on an end thereof. Cement will be flowed therethrough to fill the annulus between wellbore 15 and lower casing portion 32. Preferably, cement is flowed therethrough so that it will fill the annulus until it reaches a point above upper end 120 of annular space 40. Once the desired amount of cement has been flowed through a lower end of lower portion 34 of casing 30, a plug, such as for example plug 160 can be displaced into casing 30 so that it will engage opening sleeve 66. Plug 160 is shown in phantom lines in
As explained herein, the outermost diameter 136 of expansion cone 132 is greater than the undeformed inner diameter 93 of the upper portion 92 of outer mandrel 38. As the expansion cone 132 is forced upwardly through the upper portion 124 of annular space 40, outer mandrel 38 will radially expand. Expansion cone 132 is configured such that it will plastically deform outer mandrel 38 an amount sufficient to move sealing elements 104 into engagement with previously installed casing 20. Top and bottom rings 116 and 118 will likewise engage previously installed casing 20. Top and bottom rings 116 and 118 will act as extrusion limiters with respect to sealing elements 104. Fluid pressure applied through flow passage 37 and fluid ports 56 into annular space 40 will urge expansion cone 132 out the upper end 120 of annular space 40. Expansion cone 132 will push debris plug 90 away from upper end 120 of annular space 40, so that fluid may be circulated therethrough. Fluid will continue to be circulated through upper end 120 to wash out the leading edge of cement previously displaced into well 10. Cement will be displaced through the central flow passage 37 and flow ports 56 behind the circulation fluid until a sufficient amount has been displaced into the well to cement casing 30 and more specifically to cement the upper portion 32 thereof in previously installed casing 20.
In one embodiment outer mandrel 38 is fabricated from an alloy steel having a minimum yield strength of about 40,000 to 125,000 psi in order to optimally provide high strength and ductility. Examples of alloy steels that may be used are 4130 and 4140 alloy steels selected to have characteristics that will provide for radial expansion and plastic deformation without tearing or splitting. Material strengths and thicknesses are selected to provide performance (burst and collapse) required for specific well conditions. The thicknesses and relationships between the upper and lower portions of outer mandrel 38 and expansion cone diameter are balanced to achieve the proper contact stress with the casing 20 for pressure containment. Other alloys that may be used include Super 13Cr and Inconel 825. The examples herein are not limiting and other materials with characteristics that will provide for plastic deformation and proper sealing may be selected.
It will be seen therefore, that the present invention is well adapted to carry out the ends and advantages mentioned, as well as those inherent therein. While the presently preferred embodiment of the apparatus has been shown for the purposes of this disclosure, numerous changes in the arrangement and construction of parts may be made by those skilled in the art. All of such changes are encompassed within the scope and spirit of the appended claims.
