US20080302574A1 - Drill stem and method - Google Patents
Drill stem and method Download PDFInfo
- Publication number
- US20080302574A1 US20080302574A1 US12/134,331 US13433108A US2008302574A1 US 20080302574 A1 US20080302574 A1 US 20080302574A1 US 13433108 A US13433108 A US 13433108A US 2008302574 A1 US2008302574 A1 US 2008302574A1
- Authority
- US
- United States
- Prior art keywords
- drill stem
- sleeve
- hollow shaft
- stem segment
- shaft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
Abstract
A drill stem segment and method of manufacture are shown. Drill stem segment and methods are shown that greatly strengthen the weld joint using sleeves. reinforced butt joints are shown in selected examples where sleeves and drill stem tubes are welded to connections such as tapered thread connections. Using methods described, the drill stem segments are also inexpensive to manufacture.
Description
- This patent application claims the benefit of priority, under 35 U.S.C. Section 119(e), to U.S. Provisional Patent Application Ser. No. 60/942,888, filed on Jun. 8, 2007 which is incorporated herein by reference.
- This invention relates to drill stem devices and methods of forming. Specifically, this invention relates to devices and methods for forming drill stem segments for use with horizontal directional drills.
- Directional drilling is a useful technique for several procedures such as utility installation, etc. One common type of directional drilling is horizontal directional drilling (HDD), where a drill stem is extended essentially horizontally to form passages underground without the need for a trench. Drill heads in directional drilling typically have a feature which causes the drill head to steer in one direction when forced ahead by a drilling device. During a boring operation, pressure is applied through a drill stem from behind to the drill head. During a straight bore, the drill stem is typically rotated at a regular rate so that on average, only straight ahead drilling is accomplished. In order to steer a drill head, the rotation is temporarily stopped, and the drill head is allowed to steer in the desired direction. Once the steering maneuver is complete, the drill head is again rotated at a regular rate for straight ahead drilling.
- Drill stems are assembled in segments that are joined together as needed to extend or retract the drill stem. The drill stem segments are put under extremely large stresses such as torque for drill rotation. The flexing of drill stem while drilling a curved path further produces large stresses on drill stem segments. What is needed is an improved drill stem and method that provides advantages such as increased strength and decreased manufacturing cost.
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FIG. 1A shows a directional drill according to an embodiment of the invention. -
FIG. 1B shows another view of the directional drill according to an embodiment of the invention. -
FIG. 2 shows a cross section of an end of a drill stem segment according to the prior art. -
FIG. 3 shows a cross section of another end of a drill stem segment according to the prior art. -
FIG. 4 shows a partial cross section of an end of a drill stem segment according to an embodiment of the invention. -
FIG. 5 shows a drill stem segment according to an embodiment of the invention. - In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, mechanical or logical changes, material choice, etc. may be made without departing from the scope of the present invention.
- In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one. In this document, the term “or” is used to refer to a nonexclusive or, unless otherwise indicated. In the following description the term “breaking” unless otherwise noted refers to an operation of loosening a threaded connection where higher levels of starting friction forces are overcome, and lower sliding friction forces are then required to finish unscrewing a threaded connection. Unless otherwise noted, “breaking” does not refer to actually damaging any component. Unless otherwise noted, the term “drill stem” refers to a one or more segments of drill stem, and may include one or more tools at a distal end such as a sonde housing, a steering blade, or other drill head.
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FIG. 1A shows a horizontaldirectional drill 100. Although a horizontal directional drill is used in the following descriptions, other ground drills utilizing a number of segments of drill stem are also contemplated to be within the scope of the invention. Thedirectional drill 100 ofFIG. 1A is shown on atrack system 120 for positioning thedirectional drill 100. Although atrack system 120 is shown, other systems are also possible for use in positioning thedirectional drill 100. Wheeled systems, or combinations of tracked and wheeled systems are examples of acceptable positioning systems. Drills without a positioning system are also within the scope of the invention. - A
drilling drive block 110 is shown on thedirectional drill 100. Thedrilling drive block 110 is used to rotate a drill stem and to advance the drill stem during a drilling operation. Advancement of a drill stem is typically linear. In the example of adirectional drill 100, the advancement of the drill stem is also typically at an angle of incidence to the ground as shown inFIG. 1A . -
FIG. 1B shows a different side view of thedirectional drill 100. A storage area or hopper is shown for housing sections or segments ofdrill stem 130 as shown.FIG. 1B , further shows adrill gripping device 140 is located near a front portion of thedirectional drill 100. Thedrill gripping device 140 is useful during installation of segments of drill stem during forward drilling operations and for removal of segments of drill stem during extraction of the drill stem. -
FIG. 2 shows a close up cross section view of a prior design of adrill stem segment 200. The end of thesegment 200 shown includes atube 210 with a threadedconnection 220 attached to thetube 210. Thetube 210 includes a hollowinner portion 212 used to transmit fluid such as bentonite slurry to aid in drilling. The threadedconnection 220 shown includes afemale thread 226. Thefemale thread 226 is located adjacent to apassageway 222 that transmits the slurry through theconnection 220 and into the next drill stem segment, or into the drill head, etc. The outside of theconnection 220 includes agripping surface 224 that possesses material properties such as hardness that are sufficient to allow a device such asdrill gripping device 140 fromFIGS. 1A and 1B to hold the drill stem segment while adding or subtracting from the drill stem. - Selected drill stem segments are typically formed from two or more pieces of metal that are welded together. The
segment 200 as shown inFIG. 2 illustrates aninterface 202 where thetube 210 is typically welded to theconnection 220. A buttjoint section 228 of theconnection 220 is shown with an outside diameter that substantially matches a diameter of thetube 210. Drill stem segments such assegment 200 are subject to high stresses as discussed above. As a result, drill stem segments eventually fail and need to be replaced. A common location for failure is at the weldedinterface 202. - In some steels and other materials, heat that is applied during welding can weaken the materials in the local region of the weld. For example, hardening heat treatments can be removed at weld locations, cold working hardening can be removed, and brittle material phases can be introduced. Reinforcing the weld region in many configurations is necessary because this location is the weak link of the drill stem segment.
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FIG. 3 shows a configuration that is intended to improve the life of a drill stem segment. The end of asegment 300 shown includes atube 310 with a threadedconnection 320 attached to thetube 310. Thetube 310 includes a hollowinner portion 312 used to transmit fluid such as bentonite slurry to aid in drilling. Similar to thesegment 200 fromFIG. 2 , the outside of theconnection 320 includes agripping surface 324 that possesses material properties such as hardness that are sufficient to allow a device such asdrill gripping device 140 fromFIGS. 1A and 1B to hold the drill stem segment while adding or subtracting from the drill stem. - In the
drill stem segment 300, theend portion 314 of thetube 310 has been flared to an increased thickness. Likewise the a buttjoint section 328 of theconnection 320 includes an outside diameter that substantially matches a diameter of the flaredsection 314 of thetube 210. The increase in thickness at theinterface 302 somewhat increases the strength of the butt joint, however the manufacturing process is more expensive. -
FIG. 4 shows adrill stem segment 400 according to an embodiment of the invention. Atube 410 is attached to aconnection 420. In the example shown, theconnection 420 includes a male threaded connection 426, however the invention is not so limited. Male or female tapered threaded connections can be used. Other non-tapered threaded connections are also within the scope of the invention. Further, connection designs other than threaded connections are within the scope of the invention, such as twist and lock connections, splined connections, pinned or bolted connections, etc., however tapered threads are used for illustration as a common connection configuration. - Similar to embodiments described above, the
tube 410 includes a hollow inner portion 412 to transmit fluid such as bentonite slurry to aid in drilling. Theconnection 420 is shown with anadjacent passageway 422 to transmit drilling fluid through theconnection 420 and into the next drill stem segment, or into the drill head, etc. - A
sleeve 430 is shown fitted around thetube 410. In the configuration shown, thesleeve 430 forms aninterface 404 with theconnection 420. Thetube 410 is also shown forming aninterface 402 with theconnection 420. Thesleeve 430 provides structural reinforcement to thedrill stem segment 400 to increase the life of the component and reduce weld joint failure. In one embodiment, both thesleeve interface 404 and thetube interface 402 are welded to a buttjoint section 424 of theconnection 420. In one example, thesleeve interface 404 is welded in a separate operation from the welding of thetube interface 402. In another example, thesleeve interface 404 and thetube interface 402 are welded concurrently. - Use of a
sleeve 430 provides strengthening in a number of ways. First, there is more material at the weld joint, thereby providing a stronger joint. Further, the weld joint is located away from stress concentration locations such as 406, where thethinner tube 410 meets thesleeve 430. Any weakening of the steel or other material due to heating during a weld is offset by the increase in material thickness. - In contrast to a flared joint such as shown in
FIG. 3 , asleeve 430 is inexpensive to manufacture, and easy to assemble. In one embodiment, the sleeve is pressed onto thetube 410 with an interference fit. An interference fit keeps the sleeve from moving around prior to welding, and provides increased strength due to minimal movement betweensleeve 430 andtube 410. - In one embodiment the
tube 410 is formed from 4130 grade steel. In one embodiment, thetube 410 includes a hardness of approximately 28-30 on the Rockwell “C” scale (HRC). One example material and treatment condition includes 4130 steel that has been cold worked (for example drawn) to provide 28-30 HRC. Other examples include alternate steels or other materials that include 28-30 HRC. In one embodiment, thetube 410 includes a 1.5 inch outer diameter, with a 0.25 inch wall thickness. - Although the present invention is not limited to the material properties and dimensions listed above, some or all of these properties provide enhanced drill stem segment performance. For example using materials and dimensions as indicated, drill stem segments are provided that bend enough to steer during a boring operation. While providing sufficient flexibility to steer, embodiments using materials and dimensions as indicated are also more resistant to damage such as cold setting from bending too much. For example under many drilling circumstances, a 1.75 inch outer diameter tube will plastically deform, or cold set if bent too far during a boring operation.
- In one embodiment, the
sleeve 430 is also formed from 4130 grade steel. In one embodiment, thesleeve 430 includes a hardness of approximately 30-34 HRC. Similar to thetube 410, one example material and treatment condition includes 4130 steel that has been cold worked (for example drawn) to provide 28-30 HRC. Other materials can also be processed to include 28-30 HRC, and further, other processing methods such as heat treatments can be used in place of cold working to provide the desired hardness. Increased hardness typically provides increased tensile strength, and further resists damage from drill tooling such as clamping vices frequently used to attach and detach drill stem segments. In one embodiment, thesleeve 430 includes a 1.875 inch outer diameter, with a 0.1875 inch wall thickness. In selected embodiments, the inner diameter of thesleeve 430 is slightly smaller to provide an interference fit with thetube 410. - The
connection 420 as shown inFIG. 4 includes agripping surface 424. In the example shown inFIG. 4 , thegripping surface 424 includes an outer diameter of approximately 1.875 to match up with an outer diameter of thesleeve 430. In one embodiment theconnection 420 is formed from 4140 grade steel. In one embodiment, theconnection 420 includes a hardness of approximately 30-34 HRC. As discussed above, a number of materials and/or processing methods are possible to achieve the desired properties. As previously mentioned, increased hardness typically provides increased tensile strength, and resistance to damage from tooling such as gripping jaws. -
FIG. 5 shows an example of a competedrill stem segment 500. Atube 510 is shown, with afirst connection 532 and asecond connection 522 attached at respective ends of thetube 510. In the example shown, thefirst connection 532 includes a female tapered thread, and thesecond connection 524 includes a male tapered thread. This configuration is convenient, however the invention is not so limited. Other configurations such as male-male, or female-female threads, tapered or not tapered, or alternate connections are within the scope of the invention. - A
first sleeve 534 and asecond sleeve 524 are shown adjacent to thefirst connection 532 and thesecond connection 522 respectively. As discussed above, thesleeves tube 510 to therespective connections drill stem segment 500 is provided that greatly strengthens the weld joint using the additional material of the sleeves. Using methods discussed above, thedrill stem segment 500 is at the same time, inexpensive to manufacture. Methods shown above for example are less expensive compared to flaring ends of the tube prior to welding. - While a number of advantages of embodiments of the invention are described, the above lists are not intended to be exhaustive. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention
- It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.
- The Abstract is provided to comply with 37 C.F.R. §1.72(b), which requires that it allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.
Claims (19)
1. A drill stem segment, comprising:
a hollow shaft;
a sleeve fitted around an external surface of the hollow shaft at a shaft end wherein the sleeve aligns with the shaft end; and
a threaded connection welded to the shaft end and the sleeve.
2. The drill stem segment of claim 1 , wherein the threaded connection is butt welded to the shaft end and the sleeve.
3. The drill stem segment of claim 1 , wherein the hollow shaft includes a 1.5 inch outer diameter hollow shaft.
4. The drill stem segment of claim 3 , wherein the hollow shaft includes a 0.25 inch wall thickness.
5. The drill stem segment of claim 4 , wherein the hollow shaft includes a 4130 steel hollow shaft.
6. The drill stem segment of claim 5 , wherein the 4130 steel hollow shaft includes a Rockwell hardness C scale of approximately 28-30.
7. The drill stem segment of claim 1 , wherein the sleeve includes a 1.875 inch outer diameter and a 0.1875 inch wall thickness.
8. The drill stem segment of claim 7 , wherein the sleeve includes a Rockwell hardness C scale of approximately 28-30.
9. A drill stem segment, comprising:
a hollow steel shaft, including
a 1.5 inch outer diameter;
a 0.25 inch wall thickness;
a Rockwell hardness C scale of approximately 28-30;
a pair of sleeves fitted around an external surface of hollow shaft on each end of the shaft wherein the sleeves align with the ends of the hollow shaft; and
a pair of threaded connections butt welded to each end of the shaft and to the respective sleeves.
10. The drill stem segment of claim 9 , wherein the hollow shaft includes a 4130 steel hollow shaft.
11. The drill stem segment of claim 9 , wherein the sleeve includes a 1.875 inch outer diameter and a 0.1875 inch wall thickness.
12. The drill stem segment of claim 11 , wherein the sleeve is 4130 steel, and includes a Rockwell hardness C scale of approximately 28-30.
13. The drill stem segment of claim 11 , wherein the pair of threaded connections each include a 1.875 inch outer diameter.
14. The drill stem segment of claim 13 , wherein the pair of threaded connections each include a Rockwell hardness C scale of approximately 30-34.
15. A method of making a drill stem segment, comprising:
fitting a sleeve over an external surface of a hollow shaft at a shaft end; and
welding a threaded connection to both the hollow shaft and the sleeve.
16. The method of claim 15 , wherein welding a threaded connection to both the hollow shaft and the sleeve includes butt welding the threaded connection.
17. The method of claim 15 , wherein fitting the sleeve over the external surface of the hollow shaft includes interference fitting the sleeve.
18. The method of claim 16 , further including fitting a second sleeve over the external surface of the hollow shaft at a second shaft end, and welding a second threaded connection to both the hollow shaft and the second sleeve at the second shaft end.
19. The method of claim 18 , wherein both a male threaded connection and a female threaded connection are welded to the hollow shaft.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/134,331 US20080302574A1 (en) | 2007-06-08 | 2008-06-06 | Drill stem and method |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US94288807P | 2007-06-08 | 2007-06-08 | |
US12/134,331 US20080302574A1 (en) | 2007-06-08 | 2008-06-06 | Drill stem and method |
Publications (1)
Publication Number | Publication Date |
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US20080302574A1 true US20080302574A1 (en) | 2008-12-11 |
Family
ID=40094809
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US12/134,331 Abandoned US20080302574A1 (en) | 2007-06-08 | 2008-06-06 | Drill stem and method |
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US (1) | US20080302574A1 (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2548600A (en) * | 1948-04-29 | 1951-04-10 | Walter W Gill | Tool joint |
US4036261A (en) * | 1975-07-29 | 1977-07-19 | Service Equipment Design Co., Inc. | Thread protector for oil-well pipe and bladder incorporated therein |
US4266578A (en) * | 1976-04-23 | 1981-05-12 | Regal Tool & Rubber Co., Inc. | Drill pipe protector |
US6012744A (en) * | 1998-05-01 | 2000-01-11 | Grant Prideco, Inc. | Heavy weight drill pipe |
-
2008
- 2008-06-06 US US12/134,331 patent/US20080302574A1/en not_active Abandoned
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2548600A (en) * | 1948-04-29 | 1951-04-10 | Walter W Gill | Tool joint |
US4036261A (en) * | 1975-07-29 | 1977-07-19 | Service Equipment Design Co., Inc. | Thread protector for oil-well pipe and bladder incorporated therein |
US4266578A (en) * | 1976-04-23 | 1981-05-12 | Regal Tool & Rubber Co., Inc. | Drill pipe protector |
US6012744A (en) * | 1998-05-01 | 2000-01-11 | Grant Prideco, Inc. | Heavy weight drill pipe |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: TT TECHNOLOGIES, INC., ILLINOIS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:OLANDER, JOHN A.;REEL/FRAME:021356/0423 Effective date: 20080728 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |