METHODS FOR USING AND MAKING SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of the filing date of U.S. Provisional Patent Application No. 62/008,821 , filed June 6, 2014, and U.S. Provisional Patent Application No. 62/023014, filed July 10, 2014, both of which are incorporated herein by reference in its entirety.

FIELD

[0002] This invention relates to an inner tube assembly for receiving at least a portion of a core sample, and more particularly, to an inner tube assembly having a tapered inner surface.

BACKGROUND

[0003] In conventional drilling systems, a drill string includes an outer tube, a reaming shell securely attached to the outer tube, and a drill bit securely attached to the reaming shell. The drill string also includes an inner tube coupled to a head assembly (not shown), and the inner tube and the head assembly are seated within the outer tube. The inner tube typically has an adjustable length, and a gap is provided between the inner tube and the drill bit to permit control of fluid flow and pressure at the formation being drilled. The drill string also includes an inner tube stabilizer, a core lifter case secured to an end of the inner tube, a core lifter, and a snap ring that is used to hold the core lifter inside the core lifter case. In operation, the core lifter grips a core sample to facilitate retrieval of the sample. Typically, the inner tube has inner walls that have a consistent, straight profile relative to a longitudinal axis of the inner tube assembly. In this configuration, a sudden increase in inner diameter occurs as the core sample enters into the inner tube. This sudden change in diameter often causes segments of broken or unconsolidated core samples to settle out upon entry and wedge or seize, thereby preventing further drilling. This problem is compounded by wear ridges that are frequently formed in the inner surface of the inner tube, thereby providing potential locations for engagement with the broken or unconsolidated core samples. . [0004] Previous attempts to address these problems have been cost-prohibitive and/or resulted in performance disadvantages. For example, chrome plating is very costly, and industry supply is often constrained when the required materials are in high demand. Additionally, machining of the inner tube walls is costly, typically requires that the walls have significant thickness to avoid related distortion or damage, and can be difficult to undertake inside small diameters and over significant links. Thus, there is a need in the pertinent art for inner tubes and inner tube assemblies that address one or more of the above-referenced problems in a cost-effective manner and without sacrificing performance of the inner tube.

SUMMARY

[0005] Described herein, in one aspect, is an inner tube for receiving at least a portion of a core sample during a drilling operation. The inner tube can have a longitudinal axis and comprise a wall that circumferentially surrounds the longitudinal axis. The wall can have an inner surface and an outer surface. The inner tube can have a first end and an opposed second end spaced from the first end relative to the longitudinal axis. The second end can be configured for engagement with a core lifter case. The inner surface of the wall can define a variable inner diameter of the inner tube. The inner diameter at the first end of the inner tube can be greater than the inner diameter at the second end of the inner tube. At least a portion of the inner surface of the wall can be inwardly tapered moving from the first end toward the second end relative to the longitudinal axis.

[0006] In another aspect, an inner tube assembly for receiving at least a portion of a core sample during a drilling operation is described. The inner tube assembly can comprise an inner tube portion and a core lifter case portion. The inner tube portion can have a longitudinal axis and a wall circumferentially surrounding the longitudinal axis. The wall can have an inner surface and an outer surface. The inner tube portion has a first end and an opposed second end spaced from the first end relative to the

longitudinal axis. The inner surface of the wall can define a variable inner diameter of the inner tube portion. The inner diameter of the first end of the inner tube portion can be greater than the inner diameter at the second end of the inner tube. At least a portion of the inner surface of the wall can be inwardly tapered moving from the first end toward the second end relative to the longitudinal axis of the inner tube portion. The core lifter case portion can have a longitudinal axis and be integrally formed with the second end of the inner tube portion. The longitudinal axis of the inner tube portion can be axially aligned with the longitudinal axis of the core lifter case portion.

[0007] In an additional aspect, described herein is a method of forming an inner tube. The method can comprise applying a drawing process to the inner tube to shape an inner surface of a wall of the inner tube. The wall can circumferentially surround a longitudinal axis of the inner tube. The inner tube can have a first end and an opposed second end spaced from the first end relative to the longitudinal axis. The second end can be configured for engagement with a core lifter case. The inner surface of the wall can be shaped to define a variable inner diameter of the inner tube. The inner diameter at the first end of the inner tube can be greater than the inner diameter at the second end of the inner tube. At least a portion of the inner surface of the wall can be shaped to be inwardly tapered moving from the first end toward the second end relative to the longitudinal axis.

[0008] Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DETAILED DESCRIPTION OF THE FIGURES

[0009] These and other features of the preferred embodiments of the invention will become more apparent in the detailed description in which reference is made to the appended drawings wherein:

[0010] Figure 1 is a cross-sectional view of an exemplary inner tube having a tapered inner surface as disclosed herein. [0011] Figure 2 is a partial close-up cross-sectional view of a groove defined in the wall of the inner tube of Figure 1 as disclosed herein.

[0012] Figure 3 is a cross-sectional view of a first end portion of an exemplary inner tube as disclosed herein.

[0013] Figure 4 is a cross-sectional view of a second end portion of the inner tube of Figure 3. As shown, the second end of the inner tube is engaged with a core lifter case.

[0014] Figure 5 is a cross-sectional view of an inner tube assembly having a tapered inner surface, an inner tube portion, and a core lifter case portion as disclosed herein. As shown, the second end of the inner tube portion is integrally formed with a core lifter case portion.

[0015] Figure 6 is a cross-sectional view of a first end portion of the inner tube assembly of Figure 5.

[0016] Figure 7 is a cross-sectional view of a second end portion of the inner tube assembly of Figure 5.

DETAILED DESCRIPTION

[0017] The present invention can be understood more readily by reference to the following detailed description, examples, drawings, and claims, and their previous and following description. However, before the present devices, systems, and/or methods are disclosed and described, it is to be understood that this invention is not limited to the specific devices, systems, and/or methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0018] The following description of the invention is provided as an enabling teaching of the invention in its best, currently known embodiment. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the invention described herein, while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not in limitation thereof.

[0019] As used throughout, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a tapered portion" can include two or more such tapered portions unless the context indicates otherwise.

[0020] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0021] As used herein, the terms "optional" or "optionally" mean that the

subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0022] The word "or" as used herein means any one member of a particular list and also includes any combination of members of that list.

Inner Tube

[0023] Described herein with reference to Figures 1 -4 is an inner tube 10 for receiving at least a portion of a core sample during a drilling operation. The inner tube 10 can have a longitudinal axis 12. In exemplary aspects, the inner tube 10 can comprise a wall 14 circumferentially surrounding the longitudinal axis 12 and having an inner surface 16 and an outer surface 22.

[0024] In one aspect, the inner tube 10 can have a first end 28 and an opposed second end 32 spaced from the first end relative to the longitudinal axis 12. In this aspect, the second end 32 can optionally be configured for engagement with a core lifter case 40. It is contemplated that the inner tube 10 can have a length 25

corresponding to the distance between the first and second ends 28, 32 relative to the longitudinal axis 12 of the inner tube. Optionally, the second end 32 of the inner tube 10 can define a threaded portion 34 configured for engagement with the core lifter case 40. However, in other exemplary aspects, the second end 32 of the inner tube 10 does not define a threaded portion configured for engagement with a core lifter case. As shown in Figure 2B, when the second end 32 of the inner tube 10 operatively engages or contacts the core lifter case 40 as further described herein, a longitudinal axis 42 of the core lifter case can be substantially axially aligned with the longitudinal axis 12 of the inner tube. Upon operative engagement or contact between the second end 32 of the inner tube 10 and the core lifter case 40, the core lifter case can be configured to receive a core lifter 50 as is known in the art. In an additional aspect, the first end 28 of the inner tube 10 can define a threaded portion 30 configured for engagement with a head assembly (not shown). In a further aspect, the outer surface 22 of the inner tube 10 can have an unthreaded portion 26. In this aspect, when the second end 32 of the inner tube 10 defines a threaded portion 34, the unthreaded portion 26 can be positioned between threaded portions 30 and 34. Alternatively, when the second end 32 of the inner tube 10 does not define a threaded portion, the unthreaded portion 26 can extend from threaded portion 30 to the second end 32 of the inner tube.

[0025] In another aspect, the inner surface 16 of the wall 14 can define a variable inner diameter 18 of the inner tube 10. In this aspect, the inner diameter 18 at the first end 28 of the inner tube 10 can be greater than the inner diameter at the second end 32 of the inner tube. In an additional aspect, the unthreaded portion 26 of the outer surface 22 of the inner tube 10 can define an outer diameter 24 of the inner tube. Optionally, in this aspect, it is contemplated that the outer diameter 24 of the inner tube 10 can be substantially constant moving relative to the longitudinal axis 12.

[0026] In a further aspect, at least a portion 20 of the inner surface 16 of the wall 14 can be inwardly tapered moving from the first end 28 toward the second end 32 relative to the longitudinal axis 12. Thus, when the outer diameter 24 of the inner tube 10 is substantially constant, it is contemplated that the wall 14 of the inner tube can have a variable thickness moving relative to the longitudinal axis 12 of the inner tube. Optionally, in exemplary aspects, the inner surface 16 of the wall 14 can be consistently inwardly tapered between the first and second ends 28, 32 of the inner tube 10. In other optional aspects, it is contemplated that the inner surface 16 of the wall 14 can comprise one or more tapered portions 20. In these aspects, it is contemplated that the one or more tapered portions 20 can optionally comprise a plurality of tapered portions 20 positioned relative to the longitudinal axis 12 that, in combination, cooperate to achieve the desired change in inner diameter within the inner tube 10. In exemplary aspects, at least one tapered portion 20 of the plurality of tapered portions can have an associated taper angle that is different than a taper angle of at least one other tapered portion of the plurality of tapered portions. In exemplary aspects, the inner surface 16 of the wall 14 can optionally comprise at least one substantially non-tapered portion 21 that is blended into an adjacent tapered portion 20 of the inner surface. Optionally, in these aspects, it is contemplated that a non-tapered portion 21 can be positioned proximate the second end 32 of the inner tube 10. In use, it is contemplated that the inwardly tapered inner surface 16 of the wall 14 of the inner tube 10 can avoid the sudden inner diameter changes that are associated with conventional inner tube-core lifter case assemblies, thereby preventing undesired settling of core sample materials.

[0027] In exemplary aspects, and with reference to Figure 4, it is contemplated that the minimum angle by which the inner surface 16 of the wall 14 is inwardly tapered can correspond to the angle of a gradual, consistent taper extending from the first end 28 of the inner tube to a location proximate the core lifter. It is contemplated that the angle of the gradual, consistent taper can vary depending upon the axial length 25 of the inner tube 10. For example, it is contemplated that each inner tube 10 can have a minimum inner diameter at the first end 28 of the inner tube and a maximum inner diameter proximate the core lifter 50. It is further contemplated that the angle of the taper of the inner surface 16 of the inner tube 10 can be decreased as the length 25 of the inner tube increases. In exemplary aspects, the inner tube 10 can have an axial length 25 of about five feet. Optionally, in these aspects, it is contemplated that the angle of the taper of the inner surface 16 can range from about .02 degrees to about 0.07 degrees. In other exemplary aspects, the inner tube 10 can have an axial length 25 of about ten feet. Optionally, in these aspects, it is contemplated that the angle of the taper of the inner surface 16 can range from about 0.01 degrees to about 0.04 degrees. A table listing the outer diameter, inner diameter, and taper angles of exemplary inner tubes is provided below.

Table 1 : Dimensions of Exemplary Inner Tubes

[0028] In exemplary aspects, the outer surface 22 of the wall 14 of the inner tube 10 can define an identification groove 35 spaced a selected distance 38 from the second end 32 relative to the longitudinal axis 12. In these aspects, it is contemplated that the identification groove 35 can have a radius 36. In use, it is contemplated that

identification groove 35 can allow a drill operator to easily identify the second (thicker) end 32 of the inner tube 10, thereby ensuring that the core sample is removed in the correct direction (with the taper of the inner surface of the inner tube).

[0029] Optionally, in exemplary aspects, at least a portion of the inner surface 16 of the inner tube 10 can be coated with industrial hard-chrome plating. Alternatively, in other exemplary aspects, conventional surface treatment processes can optionally be applied to at least a portion of the inner surface 16 of the inner tube 10. In these aspects, it is contemplated that the surface treatment processes can comprise, for example and without limitation, at least one of nitriding and carburizing. In still further exemplary aspects, a fully body quench and temper hardening process can be applied to the inner tube 10 to provide wear resistance.

Inner Tube with Integrally Formed Core Lifter Case

[0030] Described herein with reference to Figures 3-7 is an inner tube assembly 100 for receiving at least a portion of a core sample during a drilling operation. The inner tube assembly 100 can comprise an inner tube portion 1 10 and a core lifter case portion 140.

[0031] In one aspect, the inner tube portion 1 10 can have a longitudinal axis 1 12 and a wall 1 14 circumferentially surrounding the longitudinal axis. In this aspect, the wall 1 14 can have an inner surface 1 16 and an outer surface 122. In another aspect, the inner tube portion 1 10 can have a first end 128 and an opposed second end 132 spaced from the first end relative to the longitudinal axis 1 12. In a further aspect, the inner surface 1 16 of the wall 1 14 can define a variable inner diameter 1 18 of the inner tube portion 1 10. In this aspect, the inner diameter 1 18 at the first end 128 of the inner tube portion 1 10 can be greater than the inner diameter at the second end 132 of the inner tube portion.

[0032] In exemplary aspects, at least a portion 120 of the inner surface 1 16 of the wall 1 14 can be inwardly tapered moving from the first end 128 toward the second end 132 relative to the longitudinal axis 1 12 of the inner tube portion 1 10. In exemplary aspects, the inner surface 1 16 of the wall 1 14 of the inner tube portion 1 10 can be consistently axially tapered between the first and second ends 128, 132 of the inner tube portion. In other optional aspects, it is contemplated that the inner surface 1 16 of the wall 1 14 of the inner tube portion 1 10 can comprise a plurality of tapered portions 120 positioned relative to the longitudinal axis 1 12. Optionally, in exemplary aspects, at least one tapered portion 120 of the plurality of tapered portions can have an associated taper angle that is different than a taper angle of at least one other tapered portion of the plurality of tapered portions. In exemplary aspects, the inner surface 1 16 of the wall tapered portion 121 that is blended into an adjacent tapered portion 120 of the inner surface. Optionally, in these aspects, it is contemplated that a non-tapered portion 121 can be positioned proximate the second end 132 of the inner tube portion 1 10. In use, it is contemplated that the inwardly tapered inner surface 1 16 of the wall 1 14 of the inner tube portion 1 10 can avoid the sudden inner diameter changes that are associated with conventional inner tube-core lifter case assemblies, thereby preventing undesired settling of core sample materials.

[0033] In exemplary aspects, and with reference to Figure 7, it is contemplated that the minimum angle by which the inner surface 1 16 of the wall 1 14 is inwardly tapered can correspond to the angle of a gradual, consistent taper extending from the first end 128 of the inner tube portion 1 10 to a location proximate the core lifter case portion 140. It is contemplated that the angle of the gradual, consistent taper can vary depending upon the axial length of the inner tube portion 1 10. For example, it is contemplated that each inner tube portion 1 10 can have a minimum inner diameter at the first end 128 of the inner tube portion and a maximum inner diameter proximate the core lifter case portion 140. It is further contemplated that the angle of the taper of the inner surface 1 16 of the inner tube portion 1 10 can be decreased as the length of the inner tube portion increases. In exemplary aspects, the inner tube portion 1 10 can have an axial length of about five feet. Optionally, in these aspects, it is contemplated that the angle of the taper of the inner surface 1 16 can range from about .02 degrees to about 0.07 degrees. In other exemplary aspects, the inner tube portion 1 10 can have an axial length of about ten feet. Optionally, in these aspects, it is contemplated that the angle of the taper of the inner surface 1 16 can range from about 0.01 degrees to about 0.04 degrees.

[0034] In an additional aspect, the outer surface 122 of the inner tube portion 1 10 can have an outer diameter 124. Optionally, in this aspect, it is contemplated that the outer diameter 124 of the inner tube 1 10 can be substantially constant moving relative to the longitudinal axis 1 12. Thus, it is contemplated that the wall 1 14 of the inner tube portion 1 10 can have a variable thickness moving relative to the longitudinal axis 1 12 of the inner tube portion. [0035] In an additional aspect, the first end 128 of the inner tube portion 1 10 can define a threaded portion 130 configured for engagement with a head assembly (not shown). In a further aspect, the outer surface 122 of the inner tube portion 10 can have an unthreaded portion 126. In this aspect, the unthreaded portion 126 can extend from threaded portion 130 to the second end 132 of the inner tube 1 10.

[0036] In an additional aspect, the core lifter case portion 140 can have a

longitudinal axis 142 and be integrally formed with the second end 132 of the inner tube portion 1 10. In this aspect, the longitudinal axis 1 12 of the inner tube portion 1 10 can be axially aligned with the longitudinal axis 142 of the core lifter case portion 140. In exemplary aspects, the core lifter case portion 140 can define a seat 145 configured to receive a core lifter 150 as is known in the art. In these aspects, as shown in Figure 7, the seat 145 can optionally comprise a circumferential ledge. In use, it is contemplated that the elimination of a threaded joint between the core lifter case portion 140 and the inner tube portion 1 10 can reduce the overall costs and maintenance associated with operation of the inner tube assembly 100 while also improving the reliability of the inner tube assembly.

[0037] Optionally, in exemplary aspects, at least a portion of the inner surface 1 16 of the inner tube assembly 100 can be coated with industrial hard-chrome plating.

Alternatively, in other exemplary aspects, conventional surface treatment processes can optionally be applied to at least a portion of the inner surface 1 16 of the inner tube assembly 100. In these aspects, it is contemplated that the surface treatment processes can comprise, for example and without limitation, at least one of nitriding and carburizing. Optionally, in still further exemplary aspects, a full-body quench and temper hardening process can optionally be applied to at least a portion of the inner tube assembly 100 to provide wear resistance.

[0038] Optionally, in some exemplary aspects, a coating of industrial hard-chrome plating and/or a surface treatment can be applied to only the core lifter case portion 140 of the inner tube assembly 100. Optionally, in further exemplary aspects, it is contemplated that a coating of one or more Composite Diamond Coatings (CDC), manufactured by Diamond Innovations, can be applied to only the core lifter case portion 140 of the inner tube assembly 100. In still further exemplary aspects, it is contemplated that a low-frequency (thru-wall) induction quench and temper hardening process can be applied to at least the core lifter case portion 140 of the inner tube assembly 100 to ensure that the strength and wear performance of the core lifter case portion matches the strength and wear performance of the core lifter case 150.

Methods of Forming an Inner Tube or Inner Tube Assembly

[0039] Also described herein is a method of forming an inner tube as disclosed herein. In one aspect, the method can comprise applying a drawing process to the inner tube to shape the inner surface of the wall of the inner tube. In this aspect, the inner surface of the wall can be shaped to define a variable inner diameter of the inner tube as disclosed herein. In exemplary aspects, the drawing process can be a tubing mill industry-standard cold drawing process that achieves mechanical reduction of wall thickness by drawing through tooling that includes engineered sets of dies and mandrels. In these aspects, it is contemplated that the tooling can be applied, either in multiple steps and stages or actively controlled in each respective drawing stage, to produce a tapered portion of the inner surface of the inner tube. In a further aspect, at least a portion of the inner surface of the wall can be shaped to be inwardly tapered moving from the first end toward the second end relative to the longitudinal axis.

Optionally, in some exemplary aspects, the inner surface of the wall can be shaped to be consistently inwardly tapered between the first and second ends of the inner tube. In further exemplary aspects, the method can comprise integrally forming the core lifter case with the second end of the inner tube as further disclosed herein. In these aspects, the method can further comprise defining the surface geometry of the core lifter case portion of the inner tube assembly using conventional metal lathe turning and milling techniques.

[0040] It is contemplated that the inner tubes and inner tube assemblies disclosed herein can be provided as part of a drilling system as is known in the art. Similarly, it is contemplated that the inner tubes and inner tube assemblies disclosed herein can be used in conventional drilling methods as are known in the art. In applications where it is necessary to extend the drill string with additional inner tubes, it is contemplated that an inner tube or inner tube assembly having a tapered inner surface as disclosed herein can serve as a first inner tube while conventional inner tubes (without a tapered inner surface) can serve as the additional inner tubes needed to extend the drill string. That is, a drill string need only include a single inner tube or inner tube assembly having the tapered inner surface; additional inner tubes can be positioned in alignment with the first inner tube such that the inner surface of the additional inner tubes adjoins the inner surface of the first end of the inner tube and has a substantially constant inner diameter.

[0041] Although several embodiments of the invention have been disclosed in the foregoing specification, it is understood by those skilled in the art that many

modifications and other embodiments of the invention will come to mind to which the invention pertains, having the benefit of the teaching presented in the foregoing description and associated drawings. It is thus understood that the invention is not limited to the specific embodiments disclosed hereinabove, and that many modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described invention, nor the claims which follow.