Patent Grant
9347275
1. Field
Embodiments disclosed herein generally relate to apparatus and methods for obtaining core sample fragments from a subterranean formation. More specifically, embodiments disclosed herein relate to fixed cutter drill bits for obtaining core sample fragments from a subterranean formation.
2. Background Art
In drilling a borehole in the earth, such as for the recovery of hydrocarbons or for other applications, it is conventional practice to connect a drill bit on the lower end of an assembly of drill pipe sections that are connected end-to-end so as to form a “drill string.” The bit is rotated by rotating the drill string at the surface or by actuation of downhole motors or turbines, or by both methods. With weight applied to the drill string, the rotating bit engages the earthen formation causing the bit to cut through the formation material by either abrasion, fracturing, or shearing action, or through a combination of all cutting methods, thereby forming a borehole along a predetermined path toward a target zone.
Many different types of drill bits have been developed and found useful in drilling such boreholes. Two predominate types of drill bits are roller cone bits and fixed cutter (or rotary drag) bits. Most fixed cutter bit designs include a plurality of blades angularly spaced about the bit face. The blades project radially outward from the bit body and form flow channels therebetween. In addition, cutting elements are typically grouped and mounted on several blades in radially extending rows. The configuration or layout of the cutting elements on the blades may vary widely, depending on a number of factors such as the formation to be drilled.
The cutting elements disposed on the blades of a fixed cutter bit are typically formed of extremely hard materials. In a typical fixed cutter bit, each cutting element comprises an elongate and generally cylindrical tungsten carbide substrate that is received and secured in a pocket formed in the surface of one of the blades. The cutting elements typically include a hard cutting layer of polycrystalline diamond (PCD) or other superabrasive materials such as thermally stable diamond or polycrystalline cubic boron nitride. These cutting elements are designed to shear formations that range from soft to medium hard. For convenience, as used herein, reference to “PDC bit” or “PDC cutters” refers to a fixed cutter bit or cutting element employing a hard cutting layer of polycrystalline diamond or other superabrasive materials.
Referring to
Cutting structure 15 is provided on face 20 of PDC bit 10. Cutting structure 15 includes a plurality of angularly spaced-apart primary blades 31, 32, 33, and secondary blades 34, 35, 36, each of which extends from bit face 20. Primary blades 31, 32, 33 and secondary blades 34, 35, 36 extend generally radially along bit face 20 and then axially along a portion of the periphery of PDC bit 10. However, secondary blades 34, 35, 36 extend radially along bit face 20 from a position that is distal bit axis 11 toward the periphery of PDC bit 10. Thus, as used herein, “secondary blade” may be used to refer to a blade that begins at some distance from the bit axis and extends generally radially along the bit face to the periphery of the bit. Primary blades 31, 32, 33 and secondary blades 34, 35, 36 are separated by drilling fluid flow courses 19.
Referring still to
Referring now to
Conventional composite blade profile 39 (most clearly shown in the right half of PDC bit 10 in
The axially lowermost point of convex shoulder region 25 and composite blade profile 39 defines a blade profile nose 27. At blade profile nose 27, the slope of a tangent line 27a to convex shoulder region 25 and composite blade profile 39 is zero. Thus, as used herein, the term “blade profile nose” refers to the point along a convex region of a composite blade profile of a bit in rotated profile view at which the slope of a tangent to the composite blade profile is zero. For most conventional fixed cutter bits (e.g., PDC bit 10), the composite blade profile includes only one convex shoulder region (e.g., convex shoulder region 25), and only one blade profile nose (e.g., nose 27). As shown in
For drilling harder formations, the mechanism for drilling changes from shearing to abrasion. For abrasive drilling, bits having fixed, abrasive elements are preferred. While PDC bits are known to be effective for drilling some formations, they have been found to be less effective for hard, very abrasive formations such as sandstone. For these hard formations, cutting structures that comprise particulate diamond, or diamond grit, impregnated in a supporting matrix are effective. In the discussion that follows, components of this type are referred to as “diamond impregnated.”
Diamond impregnated drill bits are commonly used for boring holes in very hard or abrasive rock formations. The cutting face of such bits contains natural or synthetic diamonds distributed within a supporting material (e.g., metal-matrix composites) to form an abrasive layer. During operation of the drill bit, diamonds within the abrasive layer are gradually exposed as the supporting material is worn away. The continuous exposure of new diamonds by wear of the supporting material on the cutting face is the fundamental functional principle for impregnated drill bits.
An example of a prior art diamond impregnated drill bit is shown in
Referring now to
Crown 84 may include various surface features, such as raised ribs 74. Preferably, formers are included during the manufacturing process so that the infiltrated, diamond-impregnated crown includes a plurality of holes or sockets 85 that are sized and shaped to receive a corresponding plurality of diamond-impregnated inserts 83. Once crown 84 is formed, inserts 83 are mounted in the sockets 85 and affixed by any suitable method, such as brazing, adhesive, mechanical means such as interference fit, or the like. As shown in
Referring now to
Without regard to the type of bit, the cost of drilling a borehole is proportional to the length of time it takes to drill the borehole to the desired depth and location. The drilling time, in turn, is greatly affected by the number of times the drill bit must be changed in order to reach the targeted formation. This is the case because each time the bit is changed, the entire drill string, which may be miles long, must be retrieved from the borehole section by section. Once the drill string has been retrieved and the new bit installed, the bit must be lowered to the bottom of the borehole on the drill string, which again must be constructed section by section. This process, known as a “trip” of the drill string, requires considerable time, effort, and expense. Accordingly, it is always desirable to employ drill bits that will drill faster and longer and that are usable over a wider range of differing formation hardnesses and applications.
The length of time that a drill bit may be employed before it must be changed depends upon its rate of penetration (“ROP”), as well as its durability or ability to maintain a high or acceptable ROP. Specifically, ROP is the rate that a drill bit penetrates a given subterranean formation. ROP is typically measured in feet per hour. There is an ongoing effort to optimize the design of drill bits to more rapidly drill specific formations so as to reduce drilling costs, which are significantly affected by ROP.
Once a desired formation is reached in the borehole, a core sample of the formation may be extracted for analysis. Conventionally, a hollow coring bit is employed to extract a core sample from the formation. Once the core sample has been transported from the borehole to the surface, the sample may be used to analyze and test, for example, permeability, porosity, composition, or other geological properties of the formation.
Regardless of the type of drill bit employed to drill the formation, conventional coring methods require retrieval of the drill string from the borehole, replacement of the drill bit with a coring bit, and lowering of the coring bit into the borehole on the drill string in order to retrieve a core sample, which is then taken along the path of the borehole to reach the surface for analysis. That is, conventional coring methods require tripping the drill string, and thus require considerable time, effort, and expense.
Accordingly, there is a need for fixed cutter drill bits that are capable of extracting core sample fragments from a formation during drilling, thereby avoiding tripping the drill string and reducing coring costs. Further, it is desirable for such fixed cutter drill bits to maintain acceptable ROPs for acceptable lengths of time and to avoid bit plugging when core sample fragments are extracted for surface analysis.
In one aspect, embodiments disclosed herein relate to a drill bit for obtaining core sample fragments from a subterranean formation that includes: a bit body having a bit centerline and a bit face; a plurality of blades extending radially along the bit face and separated by a plurality of flow courses therebetween, wherein one of the plurality of blades is a coring blade including: a substantially vertical surface; and an angled surface, wherein the substantially vertical surface and the angled surface are integrally connected; and a plurality of cutting elements disposed on the plurality of blades, wherein one of the plurality of cutting elements is a first cutting element disposed on the coring blade at a first radial position from the bit centerline.
In another aspect, embodiments disclosed herein relate to a drill bit for obtaining core sample fragments from a subterranean formation that includes: a bit body having a bit centerline and a bit face; a plurality of blades extending radially along the bit face and separated by a plurality of flow courses therebetween, wherein one of the plurality of blades is a coring blade, wherein one of the plurality of flow courses is an evacuation slot that is positioned across the bit centerline relative to the coring blade; and a plurality of cutting elements disposed on the plurality of blades, wherein one of the plurality of cutting elements is a first cutting element disposed on the coring blade at a first radial position from the bit centerline, wherein the first cutting element is a conical cutting element embedded in the coring blade such that an apex of the conical cutting element is oriented toward the bit centerline, wherein a support surface is disposed between the coring blade and the evacuation slot, and integrally connects the coring blade to the evacuation slot, wherein a conical insert is disposed proximate the bit centerline at the support surface, and wherein the conical insert is embedded in the bit body such that an apex of the conical insert is positioned axially above the first radial position of the first cutting element.
In another aspect, embodiments disclosed herein relate to a method of obtaining core sample fragments from a subterranean formation that includes: securing a drill bit to a lower end of a drill string; rotating the drill string to cause the drill bit to penetrate and cut through the formation, creating a wellbore; using the first cutting element of the drill bit to form a core sample fragment proximate the bit centerline of the drill bit during rotation of the drill string, wherein the core sample fragment has a width based on the first radial position of the first cutting element; using the angled surface of the coring blade to exert a lateral load on a side of the core sample fragment in order to cause the core sample fragment to break away from the formation after the core sample fragment reaches a length; relaying the core sample fragment to the evacuation slot of the drill bit; and transporting the core sample fragment from the evacuation slot to a surface of the formation via an annulus formed between the wellbore and the drill string.
In yet another aspect, embodiments disclosed herein relate to a method of obtaining a core sample fragment from a subterranean formation that includes: securing a drill bit to a lower end of a drill string; rotating the drill string to cause the drill bit to penetrate and cut through the formation, creating a wellbore; using the conical cutting element embedded in the coring blade of the drill bit to score the formation as a core sample fragment is formed proximate the bit centerline of the drill bit during rotation of the drill string, wherein the core sample fragment has a width based on the first radial position of the conical cutting element embedded in the coring blade; using the conical cutting element embedded in the coring blade to weaken the core sample fragment in order to cause the core sample fragment to break away from the formation after the core sample fragment reaches a length; in an event that the conical cutting element embedded in the coring blade fails to break the core sample fragment away from the formation, using a conical insert disposed proximate the bit centerline of the drill bit to exert a central load on an end of the core sample fragment to break the core sample fragment away from the formation after the core sample fragment reaches the length, wherein the conical insert disposed proximate the bit centerline of the drill bit is embedded in the bit body such that an apex of the conical insert is positioned axially above the first radial position of the conical cutting element embedded in the coring blade; relaying the core sample fragment to the evacuation slot of the drill bit; and transporting the core sample fragment from the evacuation slot to a surface of the formation via an annulus formed between the wellbore and the drill string.
Other aspects and advantages of the disclosure will be apparent from the following description and the appended claims.
Embodiments of the present disclosure will be described below with reference to the figures. In one aspect, embodiments disclosed herein relate to apparatus and methods for obtaining core sample fragments from a subterranean formation. In particular, embodiments disclosed herein relate to fixed cutter drill bits for obtaining core sample fragments from a subterranean formation.
Referring to
When PDC bit 700 is secured to the drill string, rotating the drill string causes PDC bit 700 to rotate and penetrate and cut through a subterranean formation using a plurality of cutting elements 713, which are described in further detail below. As PDC bit 700 penetrates and cuts through the subterranean formation, a wellbore is formed.
As shown in
As further shown in
According to one or more embodiments of the present disclosure, one of the plurality of cutting elements 713 is a first cutter (or first cutting element) 723 disposed on the coring blade 717. As described in further detail below, first cutter 723 and coring blade 717 work to form and break a core sample fragment 725, such as that shown in
As further shown in
Referring now to
Referring now to
As shown in
Referring to
Referring now to
Referring now to
As shown in
In accordance with one or more embodiments of the present disclosure, first radial position R1 is located at some distance away from bit centerline 709 to allow for the formation of core sample fragment 725. As a non-limiting example, according to one or more embodiments of the present disclosure, first radial position R1 is distanced from bit centerline 709 at a distance that measures 0.25 times the diameter of PDC bit 700. According to one or more embodiments of the present disclosure, first radial position R1 may be distanced from bit centerline 709 at a distance measuring in a range of 0.05 times the diameter of PDC bit 700 to 0.25 times the diameter of PDC bit 700. According to other embodiments of the present disclosure, first radial position R1 may be distanced from bit centerline 709 at a distance measuring in a range having a lower limit of any of 0.05, 0.075, 0.1, 0.125, or 0.15 times the diameter of PDC bit 700 to an upper limit of any of 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, or 0.25 times the diameter of PDC bit 700, where any lower limit may be used in combination with any upper limit. As understood by one of ordinary skill in the art, first radial position R1 may be located at other distances away from bit centerline 709, depending on the desired size of the core sample fragment 725, without departing from the scope of the present disclosure.
According to one or more embodiments of the present disclosure, first cutter 723 of coring blade 717 is used to form core sample fragment 725 at or near bit centerline 709 during drilling of wellbore. Specifically, first cutter 723 cuts core sample fragment 725 out of formation as PDC bit 700 rotates about bit centerline 709 during drilling of wellbore. According to one or more embodiments of the present disclosure, first cutter 723 may have a substantially planar cutting face. In other embodiments, first cutter 723 may be a conical cutting element, which is described in further detail below. The location of first radial position R1, at which first cutter 723 is disposed, determines the resulting width or diameter of the core sample fragment 725. For example, if first radial position R1 is located at a distance away from bit centerline 709 that measures 0.25 times the diameter of PDC bit 700 in accordance with one or more embodiments of the present disclosure, first cutter 723 disposed at first radial position R1 will form a core sample fragment 725 having a radius that measures 0.25 times the diameter of PDC bit 700, and a width or diameter that measures 0.5 times the diameter of PDC bit 700. The further away first radial position R1 is from bit centerline 709, the larger the width of the resulting core sample fragment 725. Likewise, the closer first radial position R1 is to bit centerline 709, the smaller the width of the resulting core sample fragment 725. Accordingly, as understood by one of ordinary skill in the art, first radial position R1 may be located at various distances away from bit centerline 709 in order to create core sample fragments 725 having various widths without departing from the scope of the present disclosure.
As further shown in
According to other embodiments of the present disclosure, coring blade 717 may be configured without relief 1303. According to these other embodiments, substantially vertical surface 1301 and angled surface 1305 are integrally connected to form a continuous piece, and are oriented to face bit centerline 709 of PDC bit 700. Further, according to these other embodiments, substantially vertical surface 1301 and angled surface 1305 intersect at a point that is axially above first cutter 723 of coring blade 717.
According to one or more embodiments of the present disclosure, substantially vertical surface 1301 may be substantially parallel to bit centerline 709 of PDC bit 700. That is, according to one or more embodiments of the present disclosure, substantially vertical surface 1301 may be oriented such that substantially vertical surface 1301 is at an angle ranging from 0 to 5 degrees, in either direction, with respect to a line parallel to bit centerline 709 of PDC bit 700. As better shown in
According to one or more embodiments of the present disclosure, angled surface 1305 has an angle in a range of 15 degrees to 20 degrees from bit centerline 709. However, in view of the above, this angle range is not intended to be limiting, and angled surface 1305 may have an angle of various degrees from bit centerline 709. For example, in one or more embodiments, angled surface 1305 may have a lower limit of any of about 5, 10, 15, 20, or 25 degrees, and an upper limit of any of 15, 20, 25, 30, 35, or 45 degrees. According to one or more embodiments of the present disclosure, angled surface 1305 may have any angle from bit centerline 709 that allows angled surface 1305 to exert a lateral load on a side of core sample fragment 725 that is sufficient to cause core sample fragment 725 to break away from formation after core sample fragment 725 reaches a desired length. The function of angled surface 1305 in this regard is described further below with respect to
Referring back to
Referring to
According to one or more embodiments of the present disclosure, low friction abrasion resistant surface 1307 is integral with substantially vertical surface 1301 and is formed during formation of coring blade 717 of PDC bit 700. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface 1307 may be either thermally stable polycrystalline diamond (TSP), natural diamond, or any other type of thermally stable abrasion resistant material. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface 1307 is TSP.
Referring to
According to one or more embodiments of the present disclosure, low friction abrasion resistant surface 1307 is integral with angled surface 1305 and is formed during formation of coring blade 717 of PDC bit 700. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface 1307 may be either TSP, natural diamond, or any other type of thermally stable abrasion resistant material. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface 1307 is TSP.
Referring now to
Still referring to
As shown, according to one or more embodiments of the present disclosure, conical insert 727 may be a rigid cutting element configured in the general shape of a cone. However, the shape of conical insert 727 is not intended to be limiting, and conical insert 727 may be configured in a different shape than a cone. As understood by one of ordinary skill in the art, according to one or more embodiments of the present disclosure, conical insert 727 may have any shape that acts to break up core sample fragment 725 that comes in contact therewith.
According to one or more embodiments of the present disclosure, conical insert 727 may be formed as an integral element of bit body 701, or as a non-integral insert made of a polycrystalline superabrasive material. According to one or more embodiments of the present disclosure, conical insert 727 is a non-integral insert that includes a substrate (such as a cemented tungsten carbide substrate) that interfaces with a diamond layer made of a polycrystalline superabrasive material, which may include, for example, polycrystalline diamond, polycrystalline cubic boron nitride, or TSP. According to one or more embodiments of the present disclosure, diamond layer forms a conical diamond working surface of conical insert 727, and substrate forms a base of conical insert 727. Without departing from the scope of the present disclosure, additional shapes, structures, compositions, and dimensions of conical insert 727 may be employed, such as those described with reference to “conical cutting elements” in U.S. Provisional Application No. 61/609,527, which is herein incorporated by reference in its entirety.
Still referring to
Further, in one or more embodiments, the fluid course 719 in which evacuation slot 721 is located comprises a greater circumferential extent of PDC bit 700 than other fluid courses 719. For example, in one or more embodiments, the fluid course 719 in which evacuation slot 721 is located comprises at least a greater than 50% surface area than the other fluid courses 719. In other embodiments, the fluid course 719 in which evacuation slot 721 is located comprises at least a greater than 75%, greater than 100%, or even greater than 150% surface area than the other fluid courses 719. Further, depending on the profile of the bit body 701, it may not be necessary to provide an evacuation slot 721 recessed into the bit body 701, but the slope of the fluid course 719 combined with the surface area of the fluid course 719 opposite the coring blade 717 may be sufficient to result in evacuation of the core sample fragment 725 from the bit body 701 into the annulus to be circulated to the surface.
Referring now to
Once core sample fragment 725 reaches a particular length, which is determined by height of coring blade 717 and the angle of angled surface 1305 with respect to bit centerline 709 as previously described above, angled surface 1305 of coring blade 717 facilitates the break of core sample fragment 725 from the formation by exerting a lateral load on one side of the newly formed core sample fragment 725. According to one or more embodiments of the present disclosure, this side-loading causes core sample fragment 725 to break away from formation at an end of core sample fragment 725 that is adjacent to formation. The end of core sample fragment 725 that is adjacent formation is the weakest area of core sample fragment 725 due to stresses imparted thereon during formation of core sample fragment 725 by first cutter 723. Accordingly, side-loading by angled surface 1305 causes core sample fragment 725 to break away from formation at the end of core sample fragment 725 that is adjacent formation, in accordance with one or more embodiments of the present disclosure.
According to one or more embodiments of the present disclosure, the resulting core sample fragment 725 has a width in a range of 0.75 inches to 1.25 inches, and a length in a range of 0.75 inches to 1.25 inches. According to other embodiments of the present disclosure, the resulting core sample fragment 725 has a width in a range of 1.9 inches to 2.1 inches, and length in a range of 1.9 inches to 2.1 inches. As understood by one of ordinary skill in the art, resulting core sample fragment 725 may have various lengths and widths without departing from the scope of the present disclosure.
As further shown in
According to other embodiments of the present disclosure, first cutter 723 may be a conical insert 727 as previously described above. In these other embodiments, conical insert 727 may be embedded in coring blade 717 at first radial position R1 such that an apex of conical insert 727 is oriented toward bit centerline 709. Further, in these other embodiments, once core sample fragment 725 reaches a particular length, which is determined by the height of coring blade 717 as previously described above, conical insert 727 creates a score in newly formed core sample fragment 725 during drilling. According to one or more embodiments of the present disclosure, this scoring causes core sample fragment 725 to weaken and break away from the formation at an end of core sample fragment 725 that is adjacent to formation. The end of core sample fragment 725 that is adjacent formation is the weakest area of core sample fragment 725 due to stresses imparted thereon during formation of core sample fragment 725 by cutting action of conical insert 727 acting as first cutter 723. Accordingly, scoring by conical insert 727 causes core sample fragment 725 to break away from formation at the end of core sample fragment 725 that is adjacent formation, in accordance with one or more embodiments of the present disclosure.
Referring now to
Embodiments having a conical cutting element 3000 as the first radial cutting element 723 may use conical cutting elements 3000 having a radius ranging from 0.010 to 0.125 inches in particular embodiments. In some embodiments, the radius r of the conical cutting element 3000 at the first radial position R1 may range from a lower limit of any of 0.01, 0.02, 0.04, 0.05, 0.06, or 0.075 inches, and an upper limit of any of 0.05, 0.06, 0.075, 0.085, 0.10, or 0.0125 inches, where any lower limit may be used in combination with any upper limit. Additionally, particular embodiments may use an asymmetrical or oblique cutting element where a cutting conical cutting end portion of the conical cutting element 3000 has an axis that is not coaxial with the axis of the substrate. Further, it may also be desirable to place the conical cutting element 3000 at a particular rake orientation (i.e., vertical or lateral orientation) on the coring blade 717 (for the given degree of asymmetry as well as cone angle for the particular conical cutting element 713) such that there is an angle α formed between the most radially interior portion of the conical cutting element 3000 and a line parallel to the bit centerline 709. In various embodiments, a may range from 0 to 45 degrees. In other embodiments, an angle α may be greater than 0 degrees. In some embodiments, the angle α may range from a lower limit of any of greater than 0, 2, 5, 10, 15, 20, or 30 degrees to an upper limit of any of 15, 20, 25, 30, 35, 40, or 45 degrees, where any lower limit may be used in combination with any upper limit. Advantageously, placement of a conical cutting element 3000 at the first radial position R1 of the coring blade 717 may allow for weakening on the core strength of the core sample fragment 725 formed in the center region of PDC bit 700 by allowing for the conical cutting element 3000 to create a score therein. Further, according to one or more embodiments of the present disclosure, coring blade 717 having conical cutting element 3000 at first radial position R1 may be configured with or without angled surface 1305 as previously described above.
In the event that the lateral load exerted by angled surface (or, according to other embodiments, the scoring by conical cutting element 3000 as the first radial cutting element 723 embedded in coring blade 717 as previously described above) is insufficient to break core sample fragment 725 away from formation, conical insert 727 embedded proximate bit centerline 709 may function to cause core sample fragment 725 to break away from formation as a back-up. Specifically, according to one or more embodiments of the present disclosure, conical insert 727 embedded proximate bit centerline 709 exerts a central load on the end of core sample fragment 725 that is closest to the apex of conical insert 727. The central load exerted by conical insert 727 causes core sample fragment 725 to fracture or crack. As a result of this central load and because conical insert 727 is disposed on or proximate bit centerline 709, core sample fragment 725 breaks into two halves. According to one or more embodiments of the present disclosure, these two halves are substantially equal in length and width.
After core sample fragment 725 is broken away from formation in accordance with one or more embodiments of the present disclosure, bit hydraulics and/or bridge portion 1000 (as previously described above) help newly extracted core sample fragment 725 to be relayed and/or directed toward evacuation slot 721 for exit of PDC bit 700. As previously described, the general downward slope of evacuation slot 721 in accordance with one or more embodiments of the present disclosure enables core sample fragment 725 to exit PDC bit 700 without bit plugging. According to one or more embodiments of the present disclosure, from evacuation slot 721, core sample fragment 725 is transported to the surface of the formation via an annulus (not shown) that is formed between the wellbore and the drill string.
Referring now to
As appreciated by one of ordinary skill in the art, such an average increase in ROP is an unexpected result for PDC bit 700, which is configured to generate core sample fragments 725 simultaneously during drilling in accordance with one or more embodiments of the present disclosure as described above. This increase in ROP for PDC bit 700 according to one or more embodiments of the present disclosure may be advantageous at least because the increase in ROP translates to an increase in the service life of PDC bit 700, an ability to drill through formations faster, and a reduction in drilling costs.
Referring now to
As appreciated by one of ordinary skill in the art, this greater normal force on first cutter 723 allows first cutter 723 to achieve a greater depth of cut per unit WOB. As further appreciated by one of ordinary skill in the art, this greater depth of cut per unit WOB results in an increased ROP of PDC bit 700. As previously described, an increase in ROP for PDC bit 700 according to one or more embodiments of the present disclosure may be advantageous at least because the increase in ROP may translate to an increase in the service life of PDC bit 700, an ability to drill through formations faster, and a reduction in drilling costs.
Referring now to
As shown in
When impregnated bit 1900 is secured to the drill string, rotating the drill string causes impregnated bit 1900 to rotate and penetrate and cut through a subterranean formation using a plurality of impregnated diamond particles and/or impregnated inserts 2005, which are described in further detail below. As impregnated bit 1900 penetrates and cuts through subterranean formation, a wellbore is formed.
As shown in
According to one or more embodiments of the present disclosure, one of the plurality of raised ribs 2007 is a coring rib 2009, which is described in further detail below. Plurality of raised ribs 2007 are separated by a plurality of channels 2011, which enable drilling fluid to flow between and both clean and cool plurality of raised ribs 2007 during drilling. According to one or more embodiments of the present disclosure, one of the plurality of channels 2011 is an evacuation slot 2013, which is described in further detail below.
As further shown in
According to one or more embodiments of the present disclosure, coring rib 2009 has a first cutter (or first cutting element) 2015 disposed thereon. As described in further detail below, first cutter 2015 and coring rib 2009 work to form and break a core sample fragment 1901, such as that shown in
As further shown in
As shown in
In accordance with one or more embodiments of the present disclosure, first radial position R1 is located at some distance away from bit centerline 2003 to allow for the formation of a core sample fragment 1901. As a non-limiting example, according to one or more embodiments of the present disclosure, first radial position R1 is distanced from bit centerline 2003 at a distance that measures 0.25 times the diameter of impregnated bit 1900. According to one or more embodiments of the present disclosure, first radial position R1 may be distanced from bit centerline 2003 at a distance measuring in a range of 0.05 times the diameter of impregnated bit 1900 to 0.25 times the diameter of impregnated bit 1900. According to other embodiments of the present disclosure, first radial position R1 may be distanced from bit centerline 2003 at a distance measuring in a range having a lower limit of any of 0.05, 0.075, 0.1, 0.125, or 0.15 times the diameter of impregnated bit 1900 to an upper limit of any of 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, or 0.25 times the diameter of impregnated bit 1900, where any lower limit may be used in combination with any upper limit. As understood by one of ordinary skill in the art, first radial position R1 may be located at other distances away from bit centerline 2003, depending on the desired size of the core sample fragment 1901, without departing from the scope of the present disclosure.
According to one or more embodiments of the present disclosure, first cutter 2015 of coring rib 2009 is used to form core sample fragment 1901 at or near bit centerline 2003 of impregnated bit 1900 during drilling of wellbore. Specifically, first cutter 2015 cuts core sample fragment 1901 out of formation as impregnated bit 1900 rotates about bit centerline 2003 during drilling of wellbore. According to one or more embodiments of the present disclosure, first cutter 2015 may have a substantially planar cutting face. In other embodiments, first cutter 2015 may be a conical cutting element 3000 as further described below. The location of first radial position R1, at which first cutter 2015 is disposed, determines the resulting width or diameter of the core sample fragment 1901. For example, if first radial position R1 is located at a distance away from bit centerline 2003 that measures 0.25 times the diameter of impregnated bit 1900 in accordance with one or more embodiments of the present disclosure, first cutter 2015 disposed at first radial position R1 will form a core sample fragment 1901 having a radius that measures 0.25 times the diameter of impregnated bit 1900, an a width or diameter that measures 0.5 times the diameter of impregnated bit 1900. The further away first radial position R1 is from bit centerline 2003, the larger the width of the resulting core sample fragment 1901. Accordingly, as understood by one of ordinary skill in the art, first radial position R1 may be located various distances away from bit centerline 2003 in order to create core sample fragments 1901 having various widths without departing from the scope of the present disclosure.
As further shown in
According to other embodiments of the present disclosure, coring rib 2009 may be configured without relief 2101. According to these other embodiments, substantially vertical surface 2100 and angled surface 2103 are integrally connected to form a continuous piece, and are oriented to face bit centerline 2003 of impregnated bit 1900. Further, according to these other embodiments, substantially vertical surface 2100 and angled surface 2103 intersect at a point that is axially above first cutter 2015 of coring rib 2009.
According to one or more embodiments of the present disclosure, substantially vertical surface 2100 may be substantially parallel to bit centerline 2003 of impregnated bit 1900. That is, according to one or more embodiments of the present disclosure, substantially vertical surface 2100 may be may be oriented such that substantially vertical surface 2100 is at an angle ranging from 0 to 5 degrees, in either direction, with respect to a line parallel to bit centerline 2003 of impregnated bit 1900. As better shown in
According to one or more embodiments of the present disclosure, angled surface 2103 has an angle in a range of 15 degrees to 20 degrees from bit centerline 2003. However, in view of the above, this angle range is not intended to be limiting, and angled surface 2103 may have an angle of various degrees from bit centerline 2003. For example, in one or more embodiments, the angled surface may have a lower limit of any of about 5, 10, 15, 20, or 25 degrees, and an upper limit of any of 15, 20, 25, 30, 35, or 45 degrees. According to one or more embodiments of the present disclosure, angled surface 2103 may have an angle from bit centerline 2003 that allows angled surface 2103, in conjunction with substantially vertical surface 2100 and relief 2101, to exert a lateral load on a side of core sample fragment 1901 that is sufficient to cause core sample fragment 1901 to break away from formation after core sample fragment 1901 reaches a desired length. The function of angled surface 2103 in this regard is described further below with respect to
Referring back to
Referring to
According to one or more embodiments of the present disclosure, low friction abrasion resistant surface 2105 is integral with substantially vertical surface 2100 and is formed during formation of coring rib 2009 of impregnated bit 1900. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface may be either TSP, natural diamond, or any other type of thermally stable abrasion resistant material. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface 2105 is TSP.
Referring to
According to one or more embodiments of the present disclosure, low friction abrasion resistant surface 2105 is integral with angled surface 2103 and is formed during formation of coring rib 2009 of impregnated bit 1900. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface 2105 may be either TSP, natural diamond, or any other type of thermally stable abrasion resistant material. According to one or more embodiments of the present disclosure, the material used for low friction abrasion resistant surface 2105 is TSP.
Referring now to
Still referring to
Still referring to
Further, in one or more embodiments, channel 2011 in which evacuation slot 2013 is located comprises a greater circumferential extent of impregnated bit 1900 than other channels 2011. For example, in one or more embodiments, the channel 2011 in which evacuation slot 2013 is located comprises at least a greater than 50% surface area than the other channels 2011. In other embodiments, the channel 2011 in which evacuation slot 2013 is located comprises at least a greater than 75%, greater than 100%, or even greater than 150% surface area than the other channels 2011. Further, depending on the profile of the bit body 2001, it may not be necessary to provide an evacuation slot 2013 recessed into the bit body 2001, but the slope of the channel 2011 combined with the surface area of the channel 2011 opposite the coring rib 2009 may be sufficient to result in evacuation of the core sample fragment 1901 from the bit body 2001 into the annulus to be circulated to the surface.
Referring now to
Referring now to
Once core sample fragment 1901 reaches a particular length, which is determined by height of coring rib 2009 and angle of angled surface 2103 with respect to bit centerline 2003 as previously described above, angled surface 2103 of coring rib 2009 facilitates the break of core sample fragment 1901 from the formation by exerting a lateral load on one side of the newly formed core sample fragment 1901. According to one or more embodiments of the present disclosure, this side-loading causes core sample fragment 1901 to break away from formation at an end of core sample fragment 1901 that is adjacent to formation. The end of core sample fragment 1901 that is adjacent formation is the weakest area of core sample fragment 1901 due to stresses imparted thereon during formation of core sample fragment 1901 by first cutter 2015. Accordingly, side-loading by angled surface 2103 causes core sample fragment 1901 to break away from formation at the end of core sample fragment 1901 that is adjacent formation, in accordance with one or more embodiments of the present disclosure.
According to one or more embodiments of the present disclosure, the resulting core sample fragment 1901 has a width in a range of 0.75 inches to 1.25 inches, and a length in a range of 0.75 inches to 1.25 inches. As understood by one of ordinary skill in the art, resulting core sample fragment 1901 may have various lengths and widths without departing from the scope of the present disclosure.
As further shown in
According to other embodiments of the present disclosure, first cutter 2015 of impregnated bit 1900 may be a conical cutting element 3000 as previously described above with reference to PDC bit 700 as shown in
Embodiments having a conical cutting element 3000 as the first radial cutting element may use conical cutting elements 3000 having a radius ranging from 0.010 to 0.125 inches in particular embodiments. In some embodiments, the radius r of the conical cutting element 3000 at the first radial position R1 may range from a lower limit of any of 0.01, 0.02, 0.04, 0.05, 0.06, or 0.075 inches, and an upper limit of any of 0.05, 0.06, 0.075, 0.085, 0.10, or 0.0125 inches, where any lower limit may be used in combination with any upper limit. Additionally, particular embodiments may use an asymmetrical or oblique cutting element where a cutting conical cutting end portion of the conical cutting element 3000 has an axis that is not coaxial with the axis of the substrate. Further, it may also be desirable to place the conical cutting element 3000 at a particular rake orientation (i.e., vertical or lateral orientation) on the coring rib 2009 (for the given degree of asymmetry as well as cone angle for the particular conical cutting element 3000) such that there is an angle α formed between the most radially interior portion of the conical cutting element 3000 and a line parallel to the bit centerline 709. In various embodiments, a may range from 0 to 45 degrees. In other embodiments, an angle α may be greater than 0 degrees. In some embodiments, the angle α may range from a lower limit of any of greater than 0, 2, 5, 10, 15, 20, or 30 degrees to an upper limit of any of 15, 20, 25, 30, 35, 40, or 45 degrees, where any lower limit may be used in combination with any upper limit. Advantageously, placement of a conical cutting element 3000 at the first radial position R1 of the coring rib 2009 may allow for weakening on the core strength of the core sample fragment 1901 formed in the center region of impregnated bit 1900 by allowing for the conical cutting element 3000 to create a score therein. Further, according to one or more embodiments of the present disclosure, coring rib 2009 having conical cutting element 3000 at first radial position R1 may be configured with or without angled surface 2103 as previously described above.
In the event that the lateral load exerted by angled surface 2103 (or, according to other embodiments, scoring by a conical cutting element 3000 embedded in coring rib 2009 as previously described above) is insufficient to break core sample fragment 1901 away from formation, a conical insert 2017 embedded proximate bit centerline 2003 may function to cause core sample fragment 1901 to break away from formation as a back-up. Specifically, according to one or more embodiments of the present disclosure, conical insert 2017 embedded proximate bit centerline 2003 exerts a central load on the end of core sample fragment 1901 that is closest to the apex of conical insert 2017. The central load exerted by conical insert 2017 causes core sample fragment 1901 to fracture or crack. As a result of this central load and because conical insert 2017 is disposed on or proximate bit centerline 2003, core sample fragment 1901 breaks into two halves. According to one or more embodiments of the present disclosure, these two halves are substantially equal in length and width.
After core sample fragment 1901 is broken away from formation in accordance with one or more embodiments of the present disclosure, bit hydraulics (as previously described above with respect to PDC bit 700) helps newly extracted core sample fragment 1901 to be relayed toward evacuation slot 2013 for exit of impregnated bit 1900. Alternatively, as previously described with respect to PDC bit 700, impregnated bit 1900 may employ a bridge portion, the mechanical structure of which creates a boundary to help direct newly extracted core sample fragment 1901 toward evacuation slot 2013 for exit of impregnated bit 1900.
As previously described, the general downward slope of evacuation slot 2013 in accordance with one or more embodiments of the present disclosure may enable core sample fragment 1901 to exit impregnated bit 1900 without bit plugging. According to one or more embodiments of the present disclosure, from evacuation slot 2013, core sample fragment 1901 is transported to the surface of the formation via an annulus (not shown) that is formed between the wellbore and the drill string. In other embodiments, as previously described, it may not be necessary to provide an evacuation slot 2013 recessed into the bit body 2001. According to these other embodiments, the slope of the channel 2011 combined with the surface area of the channel 2011 opposite the coring rib 2009 may be sufficient to result in evacuation of the core sample fragment 1901 from the bit body 2001 without bit plugging, and into the annulus to be circulated to the surface.
Referring now to
The apex of the conical inserts 727, 2017 or conical cutting elements 3000 may have curvature, including a radius of curvature. In this embodiment, the radius of curvature may range from about 0.050 to 0.125 inches. In some embodiments, the curvature may comprise a variable radius of curvature, a portion of a parabola, a portion of a hyperbola, a portion of a catenary, or a parametric spline. Further, referring to
Referring now to
Referring to
In addition to or as an alternative to a non-planar interface between the diamond layer 2600 and the carbide substrate 2601 in the conical insert 727, 2017 or conical cutting element 3000, a particular embodiment of the conical insert 727, 2017 or conical cutting element 3000 may include an interface that is not normal to the substrate body axis, as shown in
Embodiments of the present disclosure may include one or more of the following advantages. Embodiments of the present disclosure may provide for fixed cutter drill bits, such as PDC bits and impregnated bits, that are capable of forming and extracting core sample fragments from a formation simultaneously during drilling, and continuously as drilling progresses. Because embodiments of the present disclosure are capable of forming and extracting core sample fragments from a formation simultaneously during drilling, tripping the drill string, which is time consuming and expensive, may be avoided. Embodiments of the present disclosure are capable of forming core sample fragments that are of a better quality than other drill cuttings that travel uphole through the annulus. Accordingly, embodiments of the present disclosure are capable of forming core sample fragments that may provide meaningful testing and analysis of geological characteristics of the formation from which the core sample fragments were extracted. Embodiments of the present disclosure may provide for fixed cutter drill bits designed with an evacuation slot in accordance with one or more embodiments of the present disclosure that facilitates the exit of core sample fragments from the drill bit to the annulus without any risk of bit plugging. Apart from extracting quality core sample fragments from a formation, fixed cutter drill bits according to one or more embodiments of the present disclosure also exhibit an increase in ROP, which translates to an increase in the service life of fixed cutter drill bit, an ability to drill through formations faster, and a reduction in drilling costs.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
This application claims the benefit of U.S. Provisional Application 61/499,851 filed on Jun. 22, 2011, and 61/609,527 filed on Mar. 12, 2012, both of which are herein incorporated by reference in their entirety.
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