DUAL TUBE DRILL STRING COMPONENTS

FIELD

The present disclosure relates to dual tube drill string components that can be used during reverse circulation drilling operations.

BACKGROUND

Reverse circulation can be used for various purposes in drilling. For example, reverse circulation can be used for continuously sampling a formation while drilling, as disclosed in International Application Publication NO. WO 2021/034923, published Feb. 25 2021, which is hereby incorporated by reference herein and referred to hereinafter as the '923 application. Particular circumstances, such as loose or porous ground conditions, can necessitate use of dual tube drill rods to provide an outer annulus for distal fluid flow (toward the bit) and an inner bore for proximal fluid return (away from the bit). However, conventional dual tube drill rods are configured for different purposes. Namely, conventional dual tube drill rods are configured for use with pneumatic tools, such as down-the-hole hammers, which require the use of heavy drill rods having large thicknesses. Accordingly, conventional dual tube drill rods are unduly heavy, have threads that are prone to rapid wear, and are otherwise ill-suited for continuous sampling while drilling.

SUMMARY

Described herein, in various aspects, is a drill string component having a central axis. The drill string component can comprise an outer tube having a pin end and a box end. The outer tube can define an inner bore. An inner tube can be disposed within the inner bore of the outer tube. The inner tube can defines an inner bore. A plurality of rolling elements can be disposed between the outer tube and the inner tube. The wall thickness of each of the outer tube and the inner tube can be less than ¼ inch.

Additional advantages of the invention will be set forth in part in the description that 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.

DESCRIPTION OF THE DRAWINGS

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:

FIG. 1 cross sectional view of an exemplary dual tube drill string component as disclosed herein.

FIG. 2 is an enlarged partial perspective view of a box end portion of the dual tube drill string component of FIG. 1.

FIG. 3 is an exploded partial perspective view of the box end portion of the dual tube drill string component of FIG. 1.

FIG. 4 is an end view from the box end of the dual tube drill string component of FIG. 1.

FIG. 5 is an exploded view of a box end of the dual tube drill string component of FIG. 1.

FIG. 6 is an enlarged partial perspective view of a pin end portion of the dual tube drill string component of FIG. 1.

FIG. 7 is a partial sectional view of an exemplary dual tube drill string component as disclosed, the dual tube drill string component having a sealing sleeve.

FIG. 8 is a perspective view of the sealing sleeve of FIG. 7.

FIG. 9 is a partial cross sectional view of the dual tube drill string component, shown detail of the sealing sleeve.

FIG. 10 is a cross sectional view of an exemplary outer tube of a dual tube drill string component as described herein.

FIG. 11 is a cross sectional view of an exemplary outer tube of a dual tube drill string component as described herein.

FIG. 12 is a cross sectional view of an exemplary outer tube of a dual tube drill string component as described herein.

FIG. 13 illustrates a perspective view of an exemplary drill bit configured for continuous sampling while drilling using reverse circulation that can be used with the dual tube drill string components described herein.

FIG. 14 shows a perspective end view of box end portions of a plurality of drill rods.

FIG. 15 is a perspective end view of box end portions of a plurality of inner tubes of the drill rods of FIG. 14.

FIG. 16 is a perspective view of pin end portions of a plurality of drill rods as disclosed herein, the drill rods having radially extending pads.

FIG. 17 is a schematic diagram of the drill rod having radially extending pads.

FIG. 18 is a schematic view of a portion of the drill rod of FIG. 17.

FIG. 19 is a perspective view of a drill bit for use with the drill rods as disclosed herein for sampling while drilling using reverse circulation.

FIG. 20 is a distal end view of the drill bit of FIG. 19.

FIG. 21 is a cross sectional diagram of a drilling assembly comprising the drill bit as in FIG. 19, further showing the operation of fluid, drilling cuttings, and core segment flow.

FIG. 22 is a cross sectional diagram of the drilling assembly of FIG. 21.

FIG. 23 is a view of a centralizing spring as disclosed herein formed from wire.

FIG. 24 is a view of a centralizing spring as disclosed herein cut from a metal plate.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. It is to be understood that this invention is not limited to the particular methodology and protocols described, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

As used herein the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. For example, use of the term “a rolling element” can refer to one or more of such rolling elements, and so forth.

All technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs unless clearly indicated otherwise.

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. Optionally, in some aspects, when values are approximated by use of the antecedent “about,” it is contemplated that values within up to 15%, up to 10%, up to 5%, or up to 1% (above or below) of the particularly stated value can be included within the scope of those aspects. Similarly, in some optional aspects, when values are approximated by use of the terms “substantially” or “generally,” it is contemplated that values within up to 15%, up to 10%, up to 5%, or up to 1% (above or below) of the particular value can be included within the scope of those aspects. When used with respect to an identified property or circumstance, “substantially” or “generally” can refer to a degree of deviation that is sufficiently small so as to not measurably detract from the identified property or circumstance, and the exact degree of deviation allowable may in some cases depend on the specific context.

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.

As used herein, the term “at least one of” is intended to be synonymous with “one or more of.” For example, “at least one of A, B and C” explicitly includes only A, only B, only C, and combinations of each.

The word “or” as used herein means any one member of a particular list and also includes any combination of members of that list.

It is to be understood that unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow: plain meaning derived from grammatical organization or punctuation; and the number or type of aspects described in the specification.

The following description supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the apparatus, system, and associated methods of using the apparatus can be implemented and used without employing these specific details. Indeed, the apparatus, system, and associated methods can be placed into practice by modifying the illustrated apparatus, system, and associated methods and can be used in conjunction with any other apparatus and techniques conventionally used in the industry.

Referring to FIGS. 1-6, a dual tube drill string component 10 can have a central axis 12. The dual tube drill string component 10 can comprise an outer tube 14 having a box end portion 16 and an opposing pin end portion 18. The box end portion 16 can be configured to receive and couple to a pin end portion of an outer tube of an adjacent dual tube drill string component. For example, the box end portion 16 can define at least one female thread 20, and the pin end portion 18 can define at least one male thread 22. Accordingly, the box end portion 16 can be configured to receive one or more corresponding, complementary male threads of the pin end portion of the adjacent drill rod. Optionally, within the drill string, the box and pin end portions 16, 18 of the outer tube 14 can be configured for direct coupling to (e.g., interference fits with) outer tubes of adjacent dual tube drill string components.

As shown in FIG. 2, the outer tube 14 can define an inner bore 24. An inner tube 30 can be disposed with the inner bore 24 of the outer tube 14. The inner tube 30 can define an inner bore 32. The inner tube can have a female end portion 34 and a male end portion 36. The female end portion 34 can be configured to receive a male end portion of an inner tube of an adjacent dual tube drill string component. One or more sealing elements 38 (e.g., three sealing elements) can fluidly seal a coupling between the male end portion and female end portion of adjacent inner tubes. For example, as shown in FIG. 6, the sealing elements 38 can be supported between the male end portion of a first inner tube and the female end portion of a second inner tube that is coupled to the first inner tube. In some optional aspects, the sealing elements 38 can optionally comprise O-rings. In some optional aspects, and with reference to FIGS. 7-9, the sealing element 38 can comprise an annular sleeve. As illustrated in FIG. 9, the annular sleeve can, in cross sections in planes that contain the central axis 12, have circumferential ridges 39. For example, the surface of the annular sleeve can be wavy or undulating, moving along the central axis, to define the circumferential ridges 39 and areas of reduced thickness in between. The circumferential ridges can provide multiple axially-spaced areas of compression to provide an effective fluid seal.

In some aspects, the male end portion 36 of the inner tube 30 can define a respective circumferential outer groove 41 within which each sealing element 38 is received. In this way, the sealing element(s) 38 can be coupled to the male end portion 36. In alternative aspects, the female end portion 36 can define a respective circumferential inner groove within which each sealing element 38 is received. In this way, the sealing element(s) 38 can be coupled to the female end portion 34. Accordingly, the sealing element(s) 38 can be configured remain with either the male end portion 36 or the female end portion 38 upon separation of adjacent inner tubes.

In some aspects, the outer tube 14 and the inner tube 30 can have wall thicknesses (a radial dimension between outer and inner surfaces) of less than ¼ inch. For example, the wall thickness of one or both of the outer tube and the inner tube can be less than 7/32 inch, less than 3/16 inch, or about 3/16 inch.

As shown in FIG. 4, a plurality of rolling elements 40 can be disposed between the outer tube 14 and the inner tube 30. The plurality of rolling elements can be configured to enable rotation of the outer tube 18 relative to the inner tube 30. In this way, the outer tube 14 can be configured to rotate to rotationally drive a drill bit while the inner tube 30 remains rotationally stationary. In further aspects, the rolling elements 40 can serve to both radially and axially support the inner tube 30 relative to the outer tube 14. The rolling elements 40 can be, for example, balls (e.g., spherical rolling elements) or rollers (e.g., cylindrical rolling elements). In some optional aspects, the plurality of rolling elements 40 can be three rolling elements that are equally or substantially equally circumferentially spaced about the outer circumference of the inner tube.

In some aspects, and with reference to FIGS. 2-3, the outer tube 18 can comprise a first segment 44 that is coupled to a second segment 46. Optionally, the first and second segments 44, 46 can be non-permanently coupled (e.g., via a threaded coupling) or permanently coupled (e.g., via welding, such as, for example, laser welding). The first and second segments 44 and 46 can optionally be formed separately to enable assembly with the plurality of rolling elements 40 between the inner and outer tubes. The second segment 46 can have an inner surface 48 that defines an inner circumference. The inner surface 48 of the second segment can define a plurality of recesses 50 that are spaced around the inner circumference. The plurality of recesses 50 can be complementary to the rolling elements 40 and can receive portions of respective rolling elements therein, thereby supporting and locating the rolling elements. In some optional aspects, the rolling elements 40 can be retained between a first end 56 of the recess 50 and a first end 58 of the first segment 44.

The inner tube 30 can have an outer surface 52 that defines a circumferential recess 54. Said circumferential recess 54 can serve as a bearing race that can receive a portion of each rolling element 40 of the plurality of rolling elements.

In some aspects, and with reference to FIGS. 4-6, the dual tube drill string component 10 can comprise a centralizing spring 60 that is configured to bias the inner tube toward the central axis of the drill string. It is contemplated that the centralizing spring 60 can be positioned proximate to an end of the dual tube drill string component opposite the rolling elements 40. The centralizing spring 60 can be configured to support the inner tube 30 during transportation, storage, and handling. It can be understood that the inner tube can be supported by the adjacent inner tubes of adjacent dual tube drill string components during drilling. The centralizing spring 60 can have a plurality of radially extending portions 62 (e.g., three radially extending portions) that are configured to bias against the inner surface of the outer tube 30 (optionally, the first segment 46 of the outer tube) and a plurality of support sections 64 between the adjacent pairs of the radially extending portions. The inner tube 30 can define a groove 66 that can receive the support sections. In some optional aspects, the centralizing spring 60 can be generally triangular with bowed sides (e.g., optionally, shaped as an equilateral triangle and stretched over the outer surface of the inner tube 30). It is contemplated that the centralizing spring 60 can allow for a single set of rolling elements 40 positioned at a location that is offset from a center of the dual tube drill string component along the central axis 12. That is, the rolling elements 40 can all be positioned at a single location along the length of the inner tube. Further, said single location can be offset from a middle of the inner tube. Thus, the weight of the inner tube 30 can be unbalanced. The centralizing spring 60 can provide radial support so that the inner tube 30 is radially supported in at least two locations along the length of the inner tube (optionally, near opposing ends of the inner tube). The centralizing spring 60 can be a low-cost component.

In some optional aspects, and with further reference to FIG. 23, the centralizing spring 60 can be formed from a wire. For example, the wire can be spring wire, such as, for example, steel spring wire. In exemplary aspects, the wire can have a cross sectional dimension, d (e.g., diameter for a round wire) from about 1/16 inch to about ¼ inch, or being about ⅛ inch. Centralizing spring can have a gap 68 between opposed ends of the centralizing spring. The gap can be, for example, from about 1/16 inch to about ½ inch (e.g., about ⅛ inch). The gap 68 can permit the centralizing spring to compress so that, when received within the outer tube, the centralizing spring biases radially outwardly against the centralizing spring. In an uncompressed configuration, the centralizing spring can have dimensions D1 between opposed sides of about 2.7 inches, with a slightly larger dimension D2 that spans the gap 68 so that the spring can compress when inserted into the outer tube to have equal dimensions in each dimension between opposed corners and sides. In one exemplary, optional aspect, D1 can be about 2.7 inches, and D2 can be about 2.8 inches.

In alternative aspects, and with reference to FIG. 24, the centralizing spring 60 can be cut (e.g., laser cut) from a metal plate (e.g., a steel plate). The centralizing spring 60 cut from a steel plate can further be processed to provide desirable mechanical properties. For example, the centralizing spring 60) can be hardened to provide spring steel mechanical properties using methods that are used for forming conventional snap rings. The centralizing spring 60 can comprise radially extending projections 71 (e.g., three, or at least three radially extending projections) and web portions 73 that extend between circumferentially adjacent radially extending projections. The radially extending projections can optionally have arcuate outer circumferential surfaces that generally correspond to the inner circumference of the groove within which the centralizing spring is received. The centralizing spring 60 can further define a gap 68 (e.g., along the length of one web portion 73) that permits compression of the centralizing spring for receipt within the outer tube. In exemplary, optional aspects, the centralizing spring can have a thickness from ⅛ inch to about 1 inch (e.g., optionally, from about ¼ inch to about ½ inch, or about ⅜ inch). The webs can have a radial dimension of, for example, 1/16 inch to about ¼ inch (e.g., optionally, about 0.06 inches).

Optionally, the first segment 44 of the outer tube 14 can be a conventional drill rod (e.g., a wireline drill rod, which can optionally have a thickness of about 3/16 inch). It is contemplated that no modifications are needed to assemble the dual tube drill string component with a conventional drill rod as the first segment 44 of the outer tube 14. In this way, the dual tube drill string component can be disassembled to enable use of the first segment 44 for conventional coring operations such as wireline coring operations.

In some optional aspects, the first and second segments 44, 46 can have different lengths along the central axis 12. For example, as illustrated, the first segment 44 can have a greater length than the second segment 46. In alternative aspects, the first segment 44 can have a shorter length than the second segment 46. In some optional aspects, the first and second segments 44, 46 can have the same (or substantially the same) respective lengths along the central axis 12. In some aspects, both the first and second segments 44, 46 can, when disassembled, be used for conventional coring operations such as wireline coring operations.

In some aspects, the male thread(s) 22 can be case hardened. In further aspects, the female thread(s) 20 can be case hardened. In this way, the female and/or male thread(s) 20, 22, can be wear-resistant.

Referring to FIGS. 16-18, in some optional aspects, the outer tube 14 can comprise radially extending pads 90 that extend outwardly from an outer circumferential surface 90 of the outer tube. In some optional aspects, the plurality of radially extending pads 90 can comprise a plurality of wear strips 22 that can be bonded to the outer circumferential surface 90 of the outer tube 14 proximate to the pin end portion 16. In further or alternative aspects, the outer tube 14 can be formed to define the plurality of radially extending pads 90. For example, in these aspects, the radially extending pads 90 can be formed as integral portions of the outer tube 14 (such that the outer tube and the stabilizing projections are formed as one monolithic structure). The plurality of radially extending pads 90 can be spaced about the circumference of the outer tube 14. In some optional aspects, the radially extending pads 90 can be equally spaced about the circumference of the outer tube 14. In further optional aspects, the plurality of radially extending pads 90 can be unequally spaced about the circumference of the outer tube 14 such that a circumferential spacing between a first pair of radially extending pads is different than a circumferential spacing between a second pair of sequential radially extending pads.

In some aspects, the radially extending pads 90 can be positioned at the pin end portion 18 of the outer tube 14. For example, the radially extend pads 90 can extend outwardly from the circumference of the outer tube. It is contemplated that the radially extending pads 90 can reduce vibration while drilling. For example, the radially extending pads 90 can engage surfaces of the borehole to reduce vibration.

In some optional aspects, the radially extending pads 90 can be arranged in a helical orientation. For example, in some aspects, when the radially extending pads 90 comprise wear strips, the wear strips can be bonded to the outer surface 92 of the outer tube 14 in a helical orientation. In exemplary aspects, the radially extending pads 90 can each extend along a centerline 94. The centerline 94 can be spaced equally between opposed sides of the radially extending pads 90 that are spaced along an axis transverse to the longitudinal axis of the drill rod. In exemplary aspects, the centerline 94 can have a helical profile corresponding to the helical profile of the radially extending pads 90. In some aspects, the centerline 94 of each radially extending pad 90 (e.g., optionally, wear strip) of the plurality of radially extending pads 90 can intersect a cross-sectional plane 96 that contains the central axis 12 of the drill rod 10 at an acute angle θ. That is, in some optional aspects, and with reference to FIG. 3, a line tangent to the centerline 94 of each stabilizing projection 21 can form an acute angle θ with the cross-sectional plane 96 that contains the central axis 12 of the drill rod 10. In various optional aspects, the acute angle θ can be from about 5 to about 45 degrees, or from about 10 to about 30 degrees, or about 20 degrees. Optionally, the radially extending pads 90 can wrap around the outer surface 92 of the outer tube 14 in a counter-clockwise direction along an axial direction from the pin end portion to the box end portion. In this way, the radially extending pads 90 can inhibit flow of cuttings and fluid as the drill rod rotates. In further aspects, the radially extending pads 90 can wrap around the outer surface 92 of the outer tube 14 in a clockwise direction along an axial direction from the pin end portion to the box end portion.

Outer Tube with Variable Wall Thickness

Optionally, the wall thickness of the outer tube 18 can vary along the central axis 12 of the dual tube drill string component 10. In this way, the weight of the dual tube drill string component 10 can be minimized.

For example, in some aspects, the inner diameter of the outer tube 18 can vary along the length of the outer tube, while the outer diameter of the outer tube remains constant. In these aspects, it is contemplated that the wall thickness at a first end of the outer tube can be thicker than the wall thickness near a middle of the outer tube. It is contemplated that the cross-sectional wall thickness of the outer tube may vary any suitable amount. For instance, the cross-sectional wall thickness of the outer tube may be varied to the extent that the outer tube maintains sufficient structural integrity and remains compatible with reverse circulation operations as disclosed herein.

The varying cross-sectional wall thickness of the outer tube may serve many purposes. One purpose is that the varying wall thickness may provide less resistance to flow of drilling fluid through the drill string. Further, when the outer tube is used as a wireline drill rod, it is contemplated that the varying inner diameter of the outer tube may allow drilling fluid or other materials (e.g., drilling gases, drilling muds, debris, air, etc.) contained in the drill string to flow past the inner core barrel in greater volume, and therefore to flow more quickly. For example, fluid may flow past the inner core barrel as the inner barrel passes through the wider sections (e.g., near the middle of an outer tube (functioning as a drill rod)) of the drill string during tripping.

In another example, referring to FIGS. 10-12, in one aspect the outer tube 18 comprises a hollow elongate body 110 having a box end portion 120, an opposing pin end portion 130 and a cylindrical mid-body portion 140 that extends longitudinally between the respective box and pin end portions. A central longitudinal axis LA extends through the hollow body 110 between the respective box and pin end portions 120, 130. Each of the respective box and pin end portions 120, 130 have an end portion inner wall 122, 132 having a first inner diameter D1. In one aspect, the end portion inner wall 122, 132 can have a substantially cylindrical shape that is positioned uniformly about the central longitudinal axis. In a further aspect, the cylindrical mid-body portion 40 has a mid-body inner wall 142 having a variable wall diameter and a mid-body outer wall 143 having a substantially constant outer diameter. Although described herein as having the same inner diameter D1, it is contemplated that the inner walls 122, 132 of the box and pin end portions 120, 130 can optionally have different inner diameters.

In another aspect, the mid-body inner wall 142 of the mid-body portion can have at least one projecting portion having at least one male projection 144 or upset that is spaced from both the box and pin end portions 120, 130 and extends inwardly toward the central longitudinal axis LA of the hollow body 110 and a plurality of troughs 160 defined in the mid-body inner wall 142 of the mid-body portion 140. In one aspect, it is contemplated that each projection of the at least one male projection 144 has a male projection inner wall face 146 that can have a second inner diameter D2 that can be equal to or less than the first inner diameter D1. In one aspect, the male projection inner wall face 146 can have a substantially cylindrical shape that is positioned uniformly about the central longitudinal axis LA. In this aspect, each male projection 144 can have, in a perpendicular plane bisecting the central longitudinal axis LA, a substantially toroidal shape.

In another exemplary aspect, a first trough 160′ of the plurality of troughs 160 can extend from a distal end 124 of the box end portion 120 to a proximal end 150 of the at least one male projection 144 and a second trough 160″ of the plurality of troughs 160 can extend from a distal end 152 of the at least one male projection to a proximal end 134 of the pin end portion 130. In this aspect, each trough 160 can comprise a substantially cylindrical portion 162 having a first trough diameter that is greater than the respective first and second inner diameters. Each trough can also have a first frustoconical portion 164 that is sloped outwardly from the central longitudinal axis LA and extends between the respective distal end 124 of the box end portion 120 and proximal end 134 of the pin end portion 130 to the substantially cylindrical portion 162 and has a variable inner diameter that is greater than the first inner wall diameter D1. In an optional aspect, not shown, at least a portion of the substantially cylindrical portion of each trough 160 can further comprise a plurality of longitudinally extending ridges that extend inwardly toward the central longitudinal axis LA.

In a further aspect, a portion of each trough 160 adjacent to the at least one male projection 144 can comprise a second frustoconical portion 166 that is sloped inwardly from the central longitudinal axis LA and extends between the substantially cylindrical portion 162 of the mid-body portion and an edge 147 of the male projection inner wall face 146. It is contemplated that the first and second frustroconical portions 164, 166 can have any desired longitudinal cross sectional shape. In one example, and not meant to be limiting, at least a portion of each second frustoconical portion 166 can be linear in longitudinal cross-section and can be positioned at an acute angle β with respect to a perpendicular plane bisecting the central longitudinal axis LA. In one aspect, the acute angle β can be between about 0.01 to about 10 degrees; preferably less than about 8 degrees; and, more preferred, less than about 6 degrees. In exemplary aspects, the acute angle β can range from about 0.5 to about 8 degrees, from about 0.5 to about 6 degrees, from about 0.5 to about 5 degrees, from about 1 to about 7 degrees, from about 1 to about 6 degrees, from about 1 degrees to about 5 degrees, or from about 2 degrees to about 6 degrees.

In one aspect, it is contemplated that at least a portion of each second frustoconical portion 66 can be curvilinear in longitudinal cross-section. Similarly, it is contemplated that at least a portion of each first frustoconical portion 164 can be linear and/or curvilinear in longitudinal cross-section. In another aspect, at least a portion of each first frustoconical portion 164 can have a quarter sine wave shape in longitudinal cross-section with an amplitude equal to one-half of the first trough diameter.

In another aspect, and as shown in FIGS. 10 and 11, it is contemplated that the at least one male projection 144 of each projecting portion can comprise a single male projection, which can optionally extend circumferentially about the central longitudinal axis LA. Alternatively, as shown in FIG. 12, it is contemplated that the at least one male projection 144 of each projecting portion can comprise a plurality of circumferentially spaced male projections. Optionally, in exemplary aspects, the at least one projecting portion can comprise a single projecting portion (i.e., a single axial location with at least one male projection) that is positioned at a desired axial location in the mid-body portion. As one will appreciate from the above disclosure, it is contemplated that the respective end portion inner walls 122, 132 of the box and pin end portions 120, 130 can effectively act as an additional internal male projection or upset 144′ that is located at the respective outer end portions of the hollow body 110 of the outer tube 18.

Exemplary Drill String

A drill string can comprise a drill bit and least one dual tube drill string component as described herein. Optionally, the drill bit can be a bit that is configured for core sampling while drilling, as shown in FIG. 13.

In one exemplary configuration, the drill bit 200 can comprise a first body 202 and a second body 204. The drill bit 200 can have a central axis 206. The first body 202 can comprise a shank that defines an inner bore. The inner bore of the shank can define one or more female threads for coupling to a distal end of a dual tube drill string component 10.

An inner operative circumference 220 of the first body's crown 216 and an outer operative circumference 244 of the second body's crown 230 can cooperate to define a first volume 250 that is configured to receive a tubular core sample. The first volume 250 can have uniform annular cross sections in planes perpendicular to the central axis 206. In further aspects, the first volume 250 can be defined as the volume between the inner surface of the first body's crown 216 and the outer surface of the second body's crown 230. The crown 230 can further define at least one slot between opposed crown portions. The slot can define a core receiving space 242.

The bit can be configured to form and receive a tubular core sample in the first volume 250 and a core sample in the core receiving space 242. Breaking surfaces of the bit can break the tubular core sample and core sample into core pieces, and said core pieces can be carried in fluid via reverse circulation through the inner tube 30 of the dual tube drill string component 10. Further details of an exemplary bit in accordance with the present disclosure are provided in the '923 application.

Referring to FIGS. 19-22, an exemplary drill bit 400 for use with the drill rods as disclosed herein. The drill bit 400 can be configured to form core samples and carry the core samples proximally via flow through the inner tube via reverse circulation.

The drill bit 400 can have a central axis 402. The drill bit 400 can comprise a shank 404 defining an inner bore 406. The shank 404 can define at least one thread 408 (e.g., one or more female threads) that are configured to couple to the drill string.

The drill bit 400 can further comprise a crown 410, which can have a cutting face 412 that defines an outer operative circumference. An operative circumference can be defined as a continuous pathway (e.g., a circular or round pathway), formed within a plane that is perpendicular to the central axis 402, by tracing and connecting respective portions of the inner surfaces or outer surfaces of the crown. Thus, the operative circumference simulates a boundary or perimeter that would exist if the inner or outer surface of the crown extended continuously (without interruption) over 360 degrees. Accordingly an outer operative circumference can circumscribe an outer surface of the crown, and an inner operative circumference can circumscribe one or more inner surfaces of the crown.

The crown 410 can comprise a core receiving slot 416 in communication with the inner bore 406 of the shank 404. The core receiving slot 416 can define an inner operative circumference 418. That is, as the bit rotates, the cutting face 412 of the drill bit 400 can define an inner area that the cutting face 412 does not engage. Accordingly, as the drill bit 400 advances into a formation, a portion 500 of the formation within the inner operative circumference can remain intact with the formation and extend inwardly into the core receiving slot 416. In some aspects, the area of the inner operative circumference 418 can range from less than about 5 square centimeters to about 18 square centimeters in cross section. In still further aspects, the inner operative circumference 418 can have a diameter ranging from about 5 mm to about 40 mm, or from about 8 mm to about 25 mm. In further aspects, the inner operative circumference can have a diameter of less than 5 mm or greater than 40 mm.

Referring to FIGS. 21 and 22, the crown can define a base portion 440 positioned within the core receiving slot 416. Optionally, as further disclosed herein, the base portion 440 can extend between opposing sides of the core-receiving slot 416. The base portion 440 can define a breaking surface 442. At least a portion of the breaking surface can be oriented at an oblique angle to the central axis. In this way, the breaking surface can be configured so that as the portion 500 of the formation within the core receiving slot (core sample) biases against the breaking surface 442, the breaking surface can apply a stress to the core sample to cause it to break, thereby providing for collection of a core segment 502. For example, referring to FIG. 21, in some optional aspects, the breaking surface 442 can intersect a first plane including the central axis 402 and a first transverse axis 422 at a line. The line can form a break angle, a, with the first transverse axis 422. The break angle can be between about 15 and about 45 degrees, or about 30 degrees. Referring to FIG. 22, in some optional aspects, the breaking surface 442 can intersect a second plane including the central axis 402 and a second transverse axis 424 that is perpendicular to the first transverse axis 422 at an arc having a proximal concavity (a concavity that faces in a proximal direction). Thus, in some aspects, across the break surface, no plane that is tangential to the break surface can be perpendicular to the central axis 402. Optionally, in some aspects, the break surface 442 can have a conical shape with an apex 482. In some aspects, the base portion 440 can have an apex 482 that corresponds to a distal-most point on the base portion. In some aspects, the apex 482 can be radially spaced from the central axis 402. Thus, as the cylindrical core sample 604 engages the base portion 440, the cylindrical core sample can undergo a lateral force that causes the core sample to break off. Optionally, in these aspects, the apex 482 can be spaced from the central axis 402 of the drill bit 400 relative to the first transverse axis 422. Optionally, in another aspect, the apex 482 can be spaced from the central axis 402 of the drill bit 400 relative to the second transverse axis 424. In further aspects, the break surface 442 can be planar and oriented at an acute angle relative to the central axis 402.

Referring to FIGS. 21-22, a drilling assembly 600 can comprise an outer tube 14 and an inner tube 30 received within the inner tube. The inner tube 30 and outer tube 14 can cooperate to define an annular space 70. A drill bit (e.g., the drill bit 400) can be coupled to the outer tube 14. For example, the shank 404 can be threadedly coupled to the outer tube 14.

In some aspects, the drilling assembly 600 can further comprise a sub 610. The sub 610 can be configured to provide fluid communication between the core receiving slot and the inner tube 30. For example, the sub 610 can define a central bore 612 that extends between, and provides fluid communication between, the core receiving slot 416 of the crown 410 of the drill bit 400 and the inner tube 30.

Method of Use

A method can comprise forming a drill string comprising a drill bit and least one dual tube drill string component as described herein. Optionally, the drill bit can be a bit that is configured for core sampling while drilling (e.g., the bit 200 shown in FIG. 13 or the bit 400 shown in FIGS. 19-22). The drill string can be advanced into a formation. Fluid can be pumped distally (toward the bit) through an annulus 70 between the outer tube 18 and the inner tube 30 of each dual tube drill string component 10. Fluid and cuttings (and, optionally core pieces as described herein and in the '923 application) can return through the inner bore 32 of the inner tube 30.

In another aspect, a method can comprise assembling the dual tube drill string component 10 as disclosed herein with a drill rod (e.g., a wireline drill rod) serving as the outer tube 18.

In a further aspect, a method can comprise disassembling the dual tube drill string component 10 to provide a drill rod from the outer tube 18. The method can further comprise using the outer tube 18 as a drill rod in a wireline drilling operation.

In use, it is contemplated that the disclosed drill string components and drill strings can enable continuous sampling using the limited capacity of existing wireline coring drill rigs without the need for using the larger reverse-circulation pneumatic and/or rotary/energy drill rigs with which dual-tube drill string components are conventionally used.

Exemplary Aspects

In view of the described products, systems, and methods and variations thereof, herein below are described certain more particularly described aspects of the invention. These particularly recited aspects should not however be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language literally used therein.

Aspect 1: A drill string component having a central axis, the drill string component comprising:

- an outer tube having a pin end portion and a box end portion, wherein the outer tube defines an inner bore;
- an inner tube disposed within the inner bore of the outer tube, wherein the inner tube defines an inner bore; and
- a plurality of rolling elements disposed between the outer tube and the inner tube,
- wherein the wall thickness of each of the outer tube and the inner tube is less than ¼ inch.

Aspect 2: The drill string component of aspect 1, wherein the wall thickness of each of the outer tube and the inner tube is about 3/16 inch.

Aspect 3: The drill string component of aspect 1 or aspect 2, wherein the outer tube portion comprises a first segment and a second segment that is coupled to the first segment, wherein the second segment has an inner surface that defines an inner circumference, wherein inner surface of the second segment defines a plurality of recesses within the inner surface that are spaced about the inner circumference.

Aspect 4: The drill string component of aspect 3, wherein the first segment is a drill rod.

Aspect 5: The drill string component of aspect 3 or aspect 4, wherein the second segment is a drill rod.

Aspect 6: The drill string component of any one of aspects 3-5, wherein the first and second segments have the same length.

Aspect 7: The drill string component of any one of the preceding aspects, wherein the pin end portion defines at least one male thread that is case-hardened.

Aspect 8: The drill string component of any one of the preceding aspects, wherein the inner tube has an outer surface that defines a circumferential recess that is configured to receive a portion of each rolling element of the plurality of rolling elements.

Aspect 9: The drill string component of any one of the preceding aspects, further comprising a centralizing spring that is positioned between and biases against an outer surface of the inner tube and an the inner bore of the outer tube, wherein the centralizing spring is configured to bias the inner tube toward the central axis of the drill string.

Aspect 10: The drill string component of any one of the preceding aspects, wherein the outer tube has a wall thickness that varies along the central axis of the drill string component.

Aspect 11: The drill string component of any one of the preceding aspects, wherein the inner tube has a male end portion and a female end portion, wherein the drill string component further comprises at least one sealing element coupled to one of the male end portion or the female end portion.

Aspect 12: The drill string component of aspect 11, wherein the at least one sealing element comprises at least one O-ring.

Aspect 13: The drill string component of aspect 12, wherein the at least one O-ring comprises a plurality of O-rings.

Aspect 14: The drill string component of aspect 11, wherein the at least one sealing element comprises an annular sleeve.

Aspect 15: The drill string component of aspect 14, wherein the sleeve comprises a plurality of axially spaced circumferential ridges.

Aspect 16: The drill string component of any one of the preceding aspects, wherein the outer tube comprises a plurality of radially extending pads spaced about the circumference of the elongate body.

Aspect 17: The drill string component of aspect 16, wherein the plurality of radially extending pads comprise wear strips.

Aspect 18: The drill rod of any one of the preceding aspects, wherein the plurality of radially extending pads are arranged in a helical orientation.

Aspect 19: The drill rod of aspect 18, wherein the plurality of radially extending pads wrap around the drill rod in a counterclockwise direction along an axial direction from the pin end portion to the box end portion of the outer tube.

Aspect 20: The drill rod of any one of the preceding aspects, wherein each radially extending pad of the plurality of radially extending pads extends along a respective centerline, wherein the respective centerline intersects a cross-sectional plane that contains the central axis of the drill rod at an acute angle.

Aspect 21: The drill rod of aspect 18, wherein the acute angle is from about 10 degrees to about 30 degrees.

Aspect 22: The drill rod of aspect 19, wherein the acute angle is about 20 degrees.

Aspect 23: A method comprising:

- advancing a drill string comprising a drill bit and at least one drill string component, wherein the at least one drill string component comprises at least one drills string component as in any one of aspects 1-22.

Aspect 24: A method comprising:

- disassembling a first segment and a segment of an outer tube portion of a drill string component, wherein the drill string component further comprises:
  - an inner tube disposed within the inner bore of the outer tube, wherein the inner tube defines an inner bore; and
  - a plurality of rolling elements disposed between the outer tube and the inner tube,
  - wherein the wall thickness of each of the outer tube and the inner tube is less than ¼ inch,
- using the first segment as a drill rod in a wireline operation.

Aspect 25: A drill string comprising:

- a drill bit; and
- at least one drill string component coupled to the drill bit, wherein the at least one drill string component comprises at least one drill string component as in any one of aspects 1-22.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, certain changes and modifications may be practiced within the scope of the appended claims.

DUAL TUBE DRILL STRING COMPONENTS

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