The present disclosure generally relates to an assembly for a wellbore drill collar, and, more particularly (although not necessarily exclusively), to a centralizer that may fit into a wide range of drill collars for use with a drilling assembly for a wellbore.
Centralizers are devices that are used to radially space (and roughly speaking, to center) a tubing string or portion thereof from the inner diameter of a surrounding wellbore or outer tubular member. In the context of drilling a well, for example, a centralizer may be used along a drill string to substantially center the drill string or portion thereof within a wellbore. In some examples, a centralizer may be positioned internal to a drill collar of the drill string. The centralizer may be sized to allow an external portion of the centralizer to maintain contact with an inner surface of the drill collar. The size and placement of the centralizer in the drill collar may reduce vibrations in the centralizer or drill collar during operation of the drill string. The size of the centralizer may also ensure that the centralizer remains positioned to center the drilling tools in the wellbore.
Centralizers may be rigid and only positionable in a particular drill collar or a particular set of drill collars having a certain size. Centralizers that are not appropriately sized for a drill collar may not maintain contact with the inner diameter of the drill collar. Ill-fitting centralizers may result in diminished functionality of the centralizer. For example, the outer portion of the centralizer may not maintain contact with the inner diameter of the drill collar if a centralizer is too small for placement in a drill collar. This may result in the free movement or vibration of the centralizer during operation of the drill string. The movement or vibration of the centralizer may also result in the drill string departing from an intended drill path.
In some cases, a centralizer may be too large for placement internal to the drill collar. A remedy may be to trim or file the centralizer to allow the centralizer to fit into the drill collar. But, this remedy may be insufficient as it results in additional labor costs to trim the centralizer and additional time to ensure that the centralizer is trimmed to the appropriate size. Further, where a centralizer is not appropriately trimmed (e.g., where the trimming results in a centralizer that is too small for the intended drill collar), additional costs and time may be spent replacing the centralizer with an appropriately sized centralizer for the intended drill collar.
Certain aspects and features of the present disclosure relate to a centralizer that may fit into a wide range of drill collars for use with a drilling assembly for a wellbore. The term drilling assembly as used in the context of the described embodiments may broadly refer to a drill string or a portion thereof. A centralizer according to some examples may maintain contact with the drill collar inner diameter during operations and reduce vibration from ill-fitting centralizers. One example of a centralizer includes one or more fins extending radially from a body of the centralizer with chambers through a surface of the fins. The fins may be deformable to allow the centralizer to be compressed for positioning into an inner diameter of a drill collar. The centralizer may include a split-ring clamp to couple the centralizer to a drilling tool internal to the centralizer.
A centralizer according to some examples may be less stiff and be associated with a lower natural frequency, but may aid in reducing the chance that a field operator installs the wrong centralizer. Similarly, the centralizer may be useful to prevent a field operator from accidentally trimming the radially extending fins of the centralizer beyond a desired diameter, e.g., where a field operator trims too much material from the radially extending fins during installation of the centralizer in a drill collar. The centralizer may reduce vibration that downhole tools experience by maintaining contact with the inner diameter of a drill collar and not allowing one or more drilling tools in a drilling system to vibrate freely. The centralizer may be especially useful for air drilling applications in which vibration may be higher due to the lack of a heavy drilling fluid to dampen the drill string.
The terms “inner,” “outer,” “internal,” and “external” as used in the present disclosure may refer to a radial orientation toward or away from the center axis of the centralizer.
Various aspects of the present disclosure may be implemented in various drilling systems.
The drilling system 100 includes a logging-while-drilling (“LWD”) tool 110 positioned in the wellbore 106. The LWD tool 110 may include various modules, e.g., a measuring-while-drilling (“MWD”) module 112, a compensated dual resistivity (“CDR”) module 114, a saver sub 116, and a bit sub 118. The LWD tool 110, using the modules may transmit measurements of one or more characteristics (e.g., characteristics of wellbore 106) to the surface 104. Characteristic measurements may be transmitted to the surface 104 in real-time while the LWD tool 110 is positioned in the wellbore 106. The bit sub 118 may be coupled to the drill bit 108 by a drill collar that may include a centralizer according to the present disclosure.
Another example of a drilling system that may implement aspects of the present disclosure is an air drilling system. Due to the lack of a heavy drilling fluid to dampen a drill string, vibration of components of an air drilling system may be significantly increased as compared to components of a drilling system such as drilling system 100. The vibration-reduction capabilities of a centralizer according to the present disclosure may be desirable to ensure that components of the air drilling system are not permitted to vibrate freely.
The centralizer fins 204a, 204b may include one or more chambers 206 to allow the centralizer fins 204a, 204b to deform. For example, when a compression force is applied to the centralizer fins 204a, 204b in a radial direction toward the centralizer body 202, the chambers 206 may deform or change shape to allow the centralizer fins 204a, 204b to deform. The compression force applied to the centralizer fins 204a, 204b may result in a decrease in the diameter of the centralizer 200 (from the outermost edges of the centralizer fins 204a, 204b) to allow the centralizer 200 to be inserted into a drill collar having an inner surface sized to receive the centralizer 200 in a deformed state. The chambers 206 may be holes, apertures, gaps, or other types of openings extending from an outer surface 208a of the centralizer fins 204a, 204b to an opposing outer surface 208b of the centralizer fins 204a, 204b. The chambers 206 may be deformable in response to a compression force applied to the centralizer fins 204a, 204b and may be of any size or shape. Also, the size and shape of each of the chambers 206 may vary individually.
In some aspects, the size of the chambers 206 may be inversely related to the diameter of the centralizer 200 when the centralizer fins 204a, 204b are fully deformed in response to a compression force. As a result, centralizer fins 204a, 204b having larger chambers 206 may be relatively more deformable than centralizer fins 204a, 204b having smaller chambers 206. Similarly, in alternative or additional aspects, the number of chambers 206 included on the centralizer fins 204a, 204b may be inversely related to the diameter of the centralizer 200 when the centralizer fins 204a, 204b are fully deformed. As a result, the more chambers 206 included in centralizer fins 204a, 204b, the more deformable the centralizer fins 204a, 204b. The fewer chambers 206 included in centralizer fins 204a, 204b, the less deformable the centralizer fins 204a, 204b. Although multiple chambers 206 are shown in the centralizer 200 of
The shape and positioning of the chambers 206 may also affect how deformable the centralizer 200 may be when a compression force is applied to the centralizer fins 204a, 204b.
Referring back to
Referring back to
The centralizer 200 may be made of any material being rigid sufficient to reduce vibrations of one or more drilling tools when positioned in a drill collar. Although rigid, the material of the centralizer may also have some flexibility to allow the centralizer fins 204a, 204b to deform when a compression force is applied. For example, the material of the centralizer 200 may be both rigid and flexible by allowing the centralizer 200 to deform only when one or more chambers 206 are included on the centralizer fins 204a, 204b. In some aspects, the centralizer 200 may include a rubber material or plastic material (e.g., polyetherketone, polyether ether ketone, UHMB, etc.). In additional and alternative aspects, the centralizer 200 may include more than one material (e.g., where the centralizer body 202 includes a steel material and the centralizer fins 204a, 204b include a rubber material).
In block 904, the centralizer 600 may be positioned internal to the drill collar 802. For example, the centralizer 600 may be inserted, slid, or otherwise placed in the drill collar 802 to position the centralizer fins 604a, 604b, 604c proximate to the inner surface 804 of the drill collar 802. In block 906, the compression force is removed from to the centralizer fins 604a, 604b, 604c. The removal of the compression force may allow each of the centralizer fins 604a, 604b, 604c to contact an inner surface 804 of the drill collar 802. In some aspects, the centralizer fins 604a, 604b, 604c may return to their original shape. In other aspects, the centralizer fins 604a, 604b, 604c may remain partially deformed, with the amount of deformation being dependent on the diameter of the inner surface 804 of the drill collar 802. In some aspects, the removal of the compression force may be performed as the centralizer 600 is positioned internal to the drill collar 802. For example, the centralizer 600 may be partially inserted into the drill collar 802. The compression force may be removed from the compression force with the inner surface 804 of the drill collar 802 preventing the centralizer fins 604a, 604b, 604c from returning to their original shape. The remaining portions of the centralizer 600 may be slid or otherwise positioned internal to the drill collar 802 and the drill collar 802 may retain the centralizer fins 604a, 604b, 604c in a deformed state as the compression force is removed.
In some aspects, the centralizer assemblies are provided according to one or more of the following examples:
A centralizer may include a centralizer body including a through-bore for receiving a drilling component. The centralizer may also include a centralizer fin radially extending from the centralizer body. The centralizer fin may include one or more chambers defined therein. The one or more chambers may be responsive to a compression force on the centralizer fin in positioning the centralizer internally to a drill collar by changing shape such that the centralizer fin deforms.
The centralizer of Example #1 may feature the centralizer fin being made from a material. The centralizer may also feature the one or more chambers being devoid of the material.
The centralizer of Examples #1-2 may feature the material comprising a rubber material or a plastic material.
The centralizer of Examples #1-3 may feature the one or more chambers comprising a plurality of chambers. The plurality of chambers may include a center chamber and an end chamber. Each of the center chamber and the end chamber may have an oblong shape with a flat edge. The center chamber may be positioned in the centralizer fin to create a parallel relationship between the flat edge and an end surface of the centralizer fin. The end chamber may be positioned in the centralizer fin to create an angled relationship between the flat edge and the end surface of the centralizer fin.
The centralizer of Examples #1-4 may further include a split-ring clamp positionable proximate to an end portion of the centralizer body to prevent axial movement of the centralizer body. The split-ring clamp may be compressible around the drilling component in response to an end cap being positioned external to the split-ring clamp and torqued to the end portion of the centralizer body subsequent to the drilling component being positioned in the through-bore.
The centralizer of Examples #1-5 may feature the split-ring clamp including a tapered edge for mating with a corresponding tapered edge of the end cap to prevent the axial movement of the centralizer body subsequent to the end cap being torqued to the end portion of the centralizer body.
The centralizer of Examples #1-6 may also include the end cap having a passage for receiving the split-ring clamp. The end cap may include a tapered edge for mating with a corresponding tapered edge of the split-ring clamp to couple the split-ring clamp and the centralizer body to the drilling component subsequent to the end cap being torqued to the end portion of the centralizer body.
The centralizer of Examples #1-7 may feature the centralizer fin including a rubber material or a plastic material.
The centralizer of Examples #1-8 may feature the centralizer fin being positionable internal to the drill collar to reduce vibrations of one or more components of a drill string during operation of the drill string.
A centralizer assembly may include a drill collar and a centralizer. The centralizer may include a centralizer body having a through-bore. The centralizer may also include one or more centralizer fins radially extending from the centralizer body and having a plurality of chambers defined therein. The plurality of chambers may be responsive to a compression force on the centralizer fin in positioning the centralizer internally to the drill collar by changing shape such that the centralizer fin deforms. The centralizer assembly may also include a split-ring clamp positionable proximate to the centralizer body. The split-ring clamp may also be compressible around a drilling component positioned in the through-bore of the centralizer body.
The centralizer assembly of Example #10 may feature the one or more centralizer fins being positionable to contact an inner surface of the drill collar in response to a removal of the compression force to reduce vibrations in the drill collar during operation of a drill string.
The centralizer assembly of Examples #10-11 may feature the one or more centralizer fins being made from a material comprising rubber or plastic. The plurality of chambers may be devoid of the material.
The centralizer assembly of Examples #10-12 may feature the plurality of chambers including one or more center chambers and at least two end chambers. Each of one or more center chamber and the at least two end chambers may have an oblong shape with a flat edge. The one or more center chambers may be positioned in the centralizer fin to create a parallel relationship between the flat edge of each of the one or more center chambers and an end surface of the centralizer fin. Each of the at least two end chambers may be positioned in the centralizer fin to create an angled relationship between the flat edge of each of the at least two end chambers and the end surface of the centralizer fin.
The centralizer assembly of Examples #10-13 may feature the split-ring clamp including a split for allowing the split-ring clamp to compress around the drilling component. The split-ring clamp may also include the split for applying a load to the drilling component when the split-ring clamp is compressed around the drilling component.
The centralizer assembly of Examples #10-14 may further include an end cap for compressing the split-ring clamp around a part of the drilling component. The end cap may include a tapered edge for mating with a corresponding tapered edge of the split-ring clamp by torquing the end cap to an end portion of the centralizer body.
A method for installing a centralizer in a drill collar may include providing the centralizer having one or more centralizer fins extending from a centralizer body of the centralizer. The method may also include applying a compression force on the one or more centralizer fins to deform the at least one of the one or more centralizer fins based on a position of one or more chambers in the one or more centralizer fins. The method may also include positioning the centralizer internal to the drill collar. The method may also include removing the compression force to allow each of the one or more centralizer fins to contact an inner surface of the drill collar.
The method of Example #16 may also include positioning a split-ring clamp proximate to an end portion of the centralizer body and around a drilling component positioned in a through-bore of the centralizer body. The method may also include positioning the split-ring clamp internal to a passage of an end cap. The method may also include torquing the end cap to the end portion of the centralizer body to allow the split-ring clamp to apply a load on the drilling component.
The method of Examples #16-17 may feature torquing the end cap to the end portion of the centralizer body to include mating a tapered edge of the end cap with a corresponding tapered edge of the split-ring clamp.
The method of Examples #16-18 may feature the one or more chambers being positioned to extend from a first outer surface of the one or more centralizer fins to a second outer surface of the one or more centralizer fins. The method may further feature applying the compression force on the one or more centralizer fins to include causing a shape of at least one of the one or more chambers to change.
The method of Examples #16-19 may feature applying the compression force on the one or more centralizer fins to include deforming the one or more centralizer fins to produce a compressed centralizer having an outer diameter that is less than an inner diameter of the drill collar.
The foregoing description of the disclosure, including illustrated aspects and examples has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art without departing from the scope of this disclosure. Aspects and features from each disclosed example may be combined with any other example.
This is a U.S. national phase under 35 U.S.C. 371 of International Patent Application No. PCT/US2015/045666, titled “Centralizer for Use with Wellbore Drill Collar” and filed Aug. 18, 2015, which claims benefit of and priority to U.S. Provisional Patent Application No. 62/052,504, titled “Centralizer for Use with Wellbore Drill Collar” and filed Sep. 19, 2014, the entirety of each of which is incorporated herein by reference.
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PCT/US2015/045666 | 8/18/2015 | WO | 00 |
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WO2016/043901 | 3/24/2016 | WO | A |
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