Drill bits and methods for forming curved portions of a borehole

Abstract

Drill bits and methods for forming a curved portion of a borehole include a first plurality of cutting elements, such as tungsten carbide inserts, positioned at the outer or perimeter region of a bit face and oriented to bore in a direction generally perpendicular to the bit face. A second plurality of cutting elements, such as polycrystalline diamond compact cutters, are positioned at the inner region of the bit face and oriented to bore in a direction generally parallel to the bit face. When forming a curved portion of a borehole, the first plurality of cutting elements engage the formation to allow the drill bit to reorient at sharper angles than conventional methods for forming a curve, while when forming a linear portion of a borehole, the second plurality of cutting elements engage the formation to provide stability to the drill bit and a rapid rate of penetration.

Description

FIELD

Embodiments usable within the scope of the present disclosure relate, generally, to drill bits and methods of forming boreholes, and more specifically, to drill bits and methods for forming boreholes having one or more curved regions.

BACKGROUND

Directional drilling is commonly performed both to increase production of a single well (e.g., by providing bores at multiple angles to better reach one or multiple producing regions of a formation), and to minimize the environmental impact and/or surface area of such wells. Horizontal drilling is especially useful for increasing the productivity of a well, by as much as twenty times that of a vertical well, or more, by extending a substantial portion of the wellbore horizontally, through a producing layer of the formation.

While some types of non-vertical wells can be drilled simply by orienting the drill bit at a non-vertical angle (e.g., slant drilling), most modern directional drilling operations utilize a bent member, positioned near the drill bit, in conjunction with a downhole steerable mud motor. When the drill string is not rotating (e.g., when fluid is pumped through the mud motor), the bent portion of the string moves to direct the drill bit in a different direction. Then, once the drill bit reaches the desired angle, the drill string is permitted to rotate, causing the drill bit to bore in the selected direction.

Depending on the characteristics of a formation and the desired shape of a borehole, the most time consuming and difficult aspect of directional drilling normally involves “building a curve” in a directional borehole. Sometimes, multiple drilling operations are necessary, in which the drill string is removed, such that a different bent member, mud motor, and/or drill bit can be used for each portion of a curve as the angle of the borehole changes. A typical curve in a borehole can be formed using a member and/or a motor having a two-degree bend therein (e.g., a member that will change the orientation of the drill bit by two degrees for every 100 feet drilled), the angle being limited by the length and capabilities of the drill bit, the conduit used within the wellbore, and other similar factors. As such, a curved portion of a well can often have a substantial length and require a significant quantity of time and labor to form.

A need exists for drill bits and methods capable of rapidly building a curve in borehole, during a single trip, having a faster rate of penetration than conventional drill bits and methods.

A need also exists for drill bits capable of forming curves in a borehole at an angle greater than conventional drill bits and methods, thus shortening the length of a curved portion of a borehole as well as the time required to build the curve.

Embodiments usable within the scope of the present disclosure meet these needs.

SUMMARY

Embodiments usable within the scope of the present disclosure include drill bits adapted for stably and efficiently forming a curved region within a borehole. The drill bit can include a body, adapted for any desired borehole size, formed from steel, tungsten carbide matrix, or other similar materials known in the art, depending on the nature of the formation and the desired structural characteristics of the drill bit. The body can include a shank disposed at a first end (e.g., for threading and/or otherwise attaching to a drillstring or adjacent components), and a bit face disposed at a second end.

The bit face can include an outer portion and an inner portion. It should be understood that this division of the bit face into such portions is primarily conceptual, and that the bit face may or may not include separate or integral members or any physical or visible delineation between the outer and inner portions thereof. For example, in an embodiment, the “outer portion” of the bit face can include the perimeter thereof, and a portion of the bit face adjacent and immediately interior of the perimeter, while the “inner portion” can include the remainder of the bit face located interior of the outer portion (e.g., toward the center of the drill bit).

A first plurality of cutters can be positioned in the outer portion of the bit face, while a second plurality of cutters can be positioned in the inner portion. The first plurality of cutters can be oriented to bore into a formation in a direction generally perpendicular to the bit face (e.g., ahead of the drill bit by crushing and/or otherwise penetrating into the formation). The second plurality of cutters can be oriented to bore into a formation in a direction generally parallel to the bit face (e.g., ahead of the drill bit by cutting, shaving, and/or slicing into the formation in an at least partially lateral direction relative to the axis of the drill bit). In an embodiment, the first plurality of cutters can include tungsten carbide insert (TCI) cutting structures, while the second plurality of cutters can include polycrystalline diamond compact (PDC) cutting elements.

Conventionally, tungsten carbide inserts are primarily used in the gage region of a drill bit (e.g., tungsten carbide “buttons”) to maintain the gage of a borehole, prevent wear on other portions of the drill bit, prevent wobbling and/or instability of the drill bit during operation. Tungsten carbide inserts are also used in roller cone bits (e.g., rock bits). Use of tungsten carbide inserts in place of PDC cutters on the bit face of a drill bit (e.g., on the outer/perimeter region of the bit face) would generally be expected to provide an inefficient rate of penetration due to the limited cut formed by the tungsten carbide inserts. However, in embodiments of the present invention, the first plurality of cutters (e.g., tungsten carbide inserts) defines a leading edge adapted to engage the formation when forming a curved region of a borehole, while the second plurality of cutters (e.g., polycrystalline diamond compact cutters) are adapted to engage the formation when forming a linear region of the borehole. Thus, when the drill bit is urged laterally and/or otherwise manipulated to cause a curve in the path of the borehole, the first plurality of cutters, disposed on the outer portion of the bit face, define a leading edge that performs the majority of the boring responsible for extending the borehole along a curved path. For example, while boring along a curved path, a plurality of tungsten carbide inserts on the outer portion of the bit face can be used to form limited cuts in the formation, while a plurality of polycrystalline diamond compact cutting elements can form larger cuts once the inner portion of the bit face contacts the formation, thus facilitating travel of the drill bit along the curved path. When extending the borehole in a linear direction, the second plurality of cutters, disposed on the inner portion of the bit face, can perform the majority of the boring responsible for extending the borehole.

In an embodiment, the inner portion of the bit face can have a recessed region (e.g., a recessed cone shape). While the height/depth of this recessed region can vary depending on the nature of the formation and the desired structural characteristics of the drill bit, in a preferred embodiment, the height of the recessed region can be about four inches. During drilling operations, portions of the formation in front of the bit face, that are not contacted by the first plurality of cutters on the outer portion thereof, can form a “stump” that enters the recessed region. Contact between the bit face and the stump can promote stability of the drill bit and prevent undesired deviation of the drill bit from the current direction of boring. As the second plurality of cutters contact the stump, the stump can be efficiently drilled through due to the orientation and/or nature of the second plurality of cutters.

Embodiments of the present drill bit and related methods possess an enhanced rate of penetration (e.g., 200 feet per hour) over conventional PDC drill bits when forming a curved portion of a borehole, reducing the drilling time required to form a curve in a horizontal well by as much as eight to ten hours, or more. Further, embodiments of the present drill bit and method can form curves at an angle of as great as thirty five degrees, or more, though during normal operations, a curve of eighteen degrees is desirable to accommodate most types of borehole conduits. In an embodiment, the present drill bit can build a curve at an angle ranging from thirteen to twenty degrees. For example, the drill bit can drill a curve that changes direction at a rate of thirteen degrees per 100 feet drilled. In contrast, conventional curved portions of a borehole are typically formed using a bent member and/or motor having a two-degree bend. In other embodiments, the drill bit can be adapted to form a curve ranging from eight degrees to twelve degrees. In further embodiments, a drill can be adapted to form a curve ranging from eight degrees to thirty-five degrees.

To further facilitate travel of the drill bit along a sharper curved path, the overall length of the drill bit can be limited. For example, embodiments of drill bits can include a borehole gage ranging from 0.5 inches to 2 inches, with an 8.75 drill bit having a make up length of about 8 inches, when measured from the base of the shank to the front of the bit face, and a 6.5 inch drill bit having a make up length of about 5.75 inches. In a preferred embodiment, the overall length of the drill bit can be five inches or less. Use of a comparatively short drill bit positions the bit face closer to the motor than conventional drill bits, further enhancing the ability of the present drill bit to make sharp turns during boring.

While configurations of cutters on the bit face can be varied, depending on the nature of the formation and the desired structural characteristics of the drill bit, in an embodiment, the bit face can include a plurality of blades extending therefrom, with the second plurality of cutters positioned along an inner portion of the blades (e.g., toward the center of the bit face), while the first plurality of cutters are positioned along an outer portion of the blades and/or between individual blades. In further embodiments, the bit face can include a port positioned at the approximate center thereof for washing one or more of the cutters on the bit face.

Embodiments usable within the scope of the present disclosure thereby provide drill bits and methods capable of rapidly building a curve in a borehole, during a single trip, having a faster rate of penetration than conventional drill bits and methods, and/or a sharper curve than what is attainable using conventional means, thereby enabling faster and more reliable formation of curved portions of boreholes by shortening the length thereof and the time required to form such a curve.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description of various embodiments usable within the scope of the present disclosure, presented below, reference is made to the accompanying drawings, in which:

FIG. 1 depicts a side view of an embodiment of a drill bit usable within the scope of the present disclosure.

FIG. 2 depicts a front view of the drill bit of FIG. 1, showing an embodiment of the bit face thereof.

FIG. 3 depicts a perspective view of the drill bit of FIG. 1.

One or more embodiments are described below with reference to the listed Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before describing selected embodiments of the present disclosure in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein. The disclosure and description herein is illustrative and explanatory of one or more presently preferred embodiments and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, means of operation, structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit of the invention.

As well, it should be understood that the drawings are intended to illustrate and plainly disclose presently preferred embodiments to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views to facilitate understanding or explanation. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention.

Moreover, it will be understood that various directions such as “upper”, “lower”, “bottom”, “top”, “left”, “right”, and so forth are made only with respect to explanation in conjunction with the drawings, and that components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the concept(s) herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting.

Embodiments usable within the scope of the present disclosure relate to drill bits and methods adapted for forming a curved portion of a borehole more efficiently than conventional drill bits and methods. For example, an embodied drill bit can include a first plurality of cutters (e.g., tungsten carbide inserts) positioned on the outer (e.g, perimeter) portion of the bit face and oriented to bore perpendicular to (e.g., in front of and in a direction out from) the bit face, and a second plurality of cutters (e.g., polycrystalline diamond compact cutters) positioned on the inner portion (e.g., within a recessed conical region) of the bit face and oriented to bore parallel to (e.g., in front of and in a direction along) the bit face.

Referring now to FIG. 1, a diagrammatic side view of an embodiment of a drill bit (10) usable within the scope of the present disclosure is shown. The depicted drill bit (10) includes a body (12) having a shank (14) disposed at an end thereof, and a bit face (16) disposed at an opposing end. The body (12) can be formed from steel, tungsten carbide matrix materials, and/or other similar materials known in the art, depending on the characteristics of the formation within which the drill bit (10) will be used to form a borehole and/or the desired structural characteristics of the drill bit (10) (e.g., resistance to and/or dissipation of temperature, resistance to pressure, ability to withstand shock and/or vibration, etc.). The shank (14) can be formed from steel or other similar materials, and is shown having a pin shape, upon which threads can be formed for engagement with a conduit or an adjacent component. Other methods of connection to adjacent conduits and/or components, as known in the art, can be used in place of, or in addition to, the shank (14) without departing from the scope of the present disclosure. FIG. 1 depicts the bit face (16) having a plurality of blades and cutting elements thereon and a recessed conical region (44) at the approximate center thereof.

Referring now to FIG. 2, a front view of the drill bit of FIG. 1 is shown, such that the bit face (16) can be visualized in greater detail. While embodiments of the present drill bit can include any configuration of blades and/or cutting elements, depending on the desired performance of the drill bit, the nature of the formation, and/or other similar factors, FIG. 2 depicts an exemplary embodiment in which the bit face (16) includes three primary blades (18A, 18B, 18C) extending therefrom. Each primary blade (18A, 18B, 18C) extends from the center of the bit face (16) to the edge thereof, then a distance along the side of the bit face (16), as shown in FIGS. 1 and 3. Each primary blade (18A, 18B, 18C) is shown having a plurality of tungsten carbide insert cutting elements on an outer portion thereof (e.g., along the perimeter of the bit face (16) and/or along the side thereof). For example, tungsten carbide inserts (24) on the front portion of the bit face (16) and a tungsten carbide insert (26) along the side of the bit face (16), on the second primary blade (18B) are labeled for reference. Each primary blade (18A, 18B, 18C) is further shown having a plurality of polycrystalline diamond compact cutting elements on an inner portion thereof, of which a polycrystalline diamond compact cutting element (28) on the second primary blade (18B) is labeled for reference. It should be understood that the specific number and placement of cutting elements on the primary blades (18A, 18B, 18C) can vary depending on the desired characteristics of the drill bit (10). For example, for illustrative purposes, FIG. 2 depicts the first primary blade (18A) having four polycrystalline diamond compact cutting elements and two tungsten carbide insert cutting elements thereon, while the other primary blades (18B, 18C) are shown having three polycrystalline diamond compact cutting elements and three tungsten carbide insert cutting elements thereon.

FIG. 2 further depicts there secondary blades (20A, 20B, 20C), shown equidistantly spaced between the primary blades (18A, 18B, 18C), the secondary blades (20A, 20B, 20C) having a length extending along the side and outer portion (e.g., perimeter) of the bit face (16), and approximately one-half the distance from the outer portion of the bit face (16) to the center thereof. Each secondary blade (20A, 20B, 20C) is shown having tungsten carbide insert cutting elements along the outer portions thereof. For example, tungsten carbide inserts (30) on the front portion of the bit face (16) and a tungsten carbide insert (32) along the side of the bit face (16), on the third secondary blade (20C) are labeled for reference. Each secondary blade (20A, 20B, 20C) is further shown having polycrystalline diamond compact cutting elements on an inner portion thereof, of which a polycrystalline diamond compact cutting element (34) on the third secondary blade (20C) is labeled for reference. It should be understood that the specific number and placement of cutting elements on the secondary blades (20A, 20B, 20C) can vary depending on the desired characteristics of the drill bit (10). For example, for illustrative purposes, FIG. 2 depicts the second secondary blade (20B) having two tungsten carbide inserts and two polycrystalline diamond compact cutting elements thereon, while the other secondary blades (20A, 20C) have three tungsten carbide inserts and two polycrystalline diamond compact cutting elements thereon.

FIG. 2 also depicts six tertiary blades (22A, 22B, 22C, 22D, 22E, 22F) equidistantly spaced between the primary and secondary blades (18A, 18B, 18C, 20A, 20B, 20C). Each of the tertiary blades (22A, 22B, 22C, 22D, 22E, 22F) is shown having a generally short length, extending along the side and outer portion of the bit face (16), but not extending through the inner portion thereof. As such, each tertiary blade (22A, 22B, 22C, 22D, 22E, 22F) is shown having tungsten carbide insert cutting elements thereon, but lacks any polycrystalline diamond compact cutting elements. For example, the fifth tertiary blade (22E) is shown having a tungsten carbide insert (36) disposed on the front portion of the bit face (16), and a tungsten carbide insert (38) disposed along the side of the bit face (16). It should be understood that the specific number and placement of cutting elements on the tertiary blades (22A, 22B, 22C, 22D, 22E, 22F) can vary depending on the desired characteristics of the drill bit (10). For example, for illustrative purposes, FIG. 2 depicts the third and sixth tertiary blades (22C, 22F) having three tungsten carbide inserts thereon, while the other tertiary blades (22A, 22B, 22D, 22E) are shown having two tungsten carbide inserts thereon. Additionally, while the depicted embodiment of the drill bit (10) lacks any polycrystalline diamond compact cutting elements on the tertiary blades (22A, 22B, 22C, 22D, 22E, 22F), in other embodiments, the length of the tertiary blades (22A, 22B, 22C, 22D, 22E, 22F) can be longer and/or the inner portion of the tertiary blades (22A, 22B, 22C, 22D, 22E, 22F) can include polycrystalline diamond compact cutters.

The depicted drill bit (10) is further shown having a plurality of jets, ports, and or nozzles, oriented to wash the blades and/or cutting elements, of which a jet (40) is labeled for reference. A port nozzle (42) is shown at the approximate center of the bit face (16), and is further usable for washing the cutters and/or blades, circulating fluid, and/or engaging the formation or various objects. In an embodiment, the inner portion of the bit face (16) can include a recessed conical region (44). For example, FIGS. 1 through 3 depict the bit face (16) having a recessed conical region (44) with an apex at the approximate center of the bit face (16). While the depth/height of the recessed conical region (44) can vary depending on the nature of the drill bit, in an embodiment, the recessed conical region (44) can have a height of approximately four inches.

Referring now to FIG. 3, a perspective view of the drill bit (10) of FIG. 1 is shown. As described previously, the depicted drill bit (10) includes a body (12), shank (14), and bit face (16). The bit face (16) is shown having a plurality of primary blades, of which a primary blade (18) is labeled for reference, the primary blade (18) including one or more tungsten carbide inserts (24) disposed on the front portion of the bit face (16), one or more tungsten carbide inserts (26) disposed on the side of the bit face (16), and one or more polycrystalline diamond compact cutting elements (28) disposed on the inner portion of the primary blade (18). The bit face (16) is further shown having a plurality of secondary blades, of which a secondary blade (20) is labeled for reference. The secondary blade (20) is shown having one or more tungsten carbide inserts (30) disposed on the front of the bit face (16), one or more tungsten carbide inserts (32) disposed on the side of the bit face (16), and one or more polycrystalline diamond compact cutting elements (34) disposed on the inner portion of the secondary blade (20). The bit face (16) is additionally shown having a plurality of tertiary blades, of which a tertiary blade (22) is labeled for reference. The tertiary blade (22) is shown having one or more tungsten carbide inserts (36) disposed on the front portion of the bit face (16), and one or more tungsten carbide inserts (38) disposed on the side of the bit face (16).

In use, the depicted drill bit (10) can be run into a borehole (e.g., through attachment to a string of drill pipe or a similar conduit and/or conveyance), typically at a time when it is desirable to form a curved portion of the borehole. Once positioned at a point where drilling operations are to be performed, the drill bit can be actuated such that the cutting elements thereof rotate relative to the formation. When boring in a generally straight (e.g, linear) direction, the plurality of tungsten carbide inserts disposed at the outer portion of the bit face will contact the formation prior to the polycrystalline diamond compact cutting elements, and can crush the formation to form limited cuts therein, while a portion of the formation in front of the bit face that is not contacted by the tungsten carbide inserts (e.g., a “stump”) enters the recessed conical portion of the bit face to provide stability thereto and maintain the direction of the drill bit. The polycrystalline diamond compact cutting elements would then bore through the stump as the drill bit progressed through the formation.

When boring along a curved path (e.g., when building a curve in a borehole), the drill bit can be urged in a lateral direction at a rate that will cause turning and/or reorientation of the drill bit at a desired angular rate of change (e.g., through selection of a lateral force corresponding to the desired angle of the curve). The tungsten carbide insert cutting elements, disposed along the outer portion (e.g., perimeter and side portions) of the bit face and oriented to crush the formation in a direction perpendicular to the bit face (e.g., outward from the front portion thereof), will remove the formation in a manner that allows the drill bit to turn sharply. Portions of the formation, not contacted by the tungsten carbide inserts along the outer portion of the bit face (e.g., formation that enters the recessed conical region), will be removed by the polycrystalline diamond compact cutting elements, which displace such portions of the formation in a direction generally parallel to the bit face.

Embodiments usable within the scope of the present disclosure thereby provide drill bits and methods capable of rapidly building a curve in borehole, during a single trip, having a faster rate of penetration than conventional drill bits and methods, and capable of forming curves an angle greater than conventional drill bits and methods, thus shortening the length of a curved portion of a borehole as well as the time required to build the curve.

While various embodiments usable within the scope of the present disclosure have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention can be practiced other than as specifically described herein.

Claims

1. A drill bit adapted for forming a curved portion of a borehole, the drill bit comprising:

a body having a first end and a second end;

a shank disposed at the first end of the body, wherein the shank is adapted for attachment to a drill string, a downhole component, or combinations thereof;

a bit face disposed at the second end of the body, wherein the bit face comprises a perimeter region and an interior region, and wherein the interior region comprises a recessed conical portion for contacting a formation to provide stability to the drill bit;

a plurality of tungsten carbide inserts disposed in the perimeter region, wherein the plurality of tungsten carbide inserts define a leading edge oriented to bore into the formation in a direction generally perpendicular to the bit face; and

a plurality of polycrystalline diamond compact cutting elements disposed in the interior region, wherein the plurality of polycrystalline diamond compact cutting elements are oriented to bore into the formation in a direction generally parallel to the bit face, wherein the plurality of tungsten carbide inserts are adapted to engage the formation to form a curved region of a borehole, and wherein the plurality of polycrystalline diamond compact cutting elements are adapted to engage the formation to form a linear region of the borehole.

2. The drill bit of claim 1, wherein the recessed conical portion comprises a height of four inches or less.

3. The drill bit of claim 1, wherein the recessed conical portion comprises a height of four inches or greater.

4. The drill bit of claim 1, wherein the plurality of polycrystalline diamond compact cutting elements forms a first cut in the formation having a first dimension, and wherein the plurality of tungsten carbide inserts forms a second cut in the formation having a second dimension less than the first dimension for facilitating boring of the drill bit along a curved path.

5. The drill bit of claim 1, wherein the body comprises an overall length of five inches or less.

6. The drill bit of claim 1, wherein the bit face comprises a plurality of blades extending therefrom, wherein the plurality of polycrystalline diamond compact cutting elements are positioned along an inner portion of the plurality of blades, and wherein the plurality of tungsten carbide inserts are positioned along an outer portion of the plurality of blades, between individual blades of the plurality of blades, or combinations thereof.

7. The drill bit of claim 1, further comprising a port positioned at a center of the bit face for washing the plurality of tungsten carbide inserts, the plurality of polycrystalline diamond compact cutting elements, or combinations thereof.

8. A method for forming a borehole, the method comprising the steps of:

providing a drill bit into a borehole, wherein the drill bit comprises a bit face having a first plurality of cutters disposed on an outer portion thereof to define a leading edge and a second plurality of cutters disposed on an inner portion thereof; and

forming a curved portion of the borehole by using the first plurality of cutters to bore through a formation in a direction generally perpendicular to the bit face while urging the drill bit along a curved path.

9. The method of claim 8, further comprising the step of forming a linear portion of the borehole by using the second plurality of cutters to bore through a formation in a direction generally parallel to the bit face while urging the drill bit along a linear path.

10. The method of claim 9, wherein the inner portion of the bit face comprises a recessed cone, a recessed dome, or combinations thereof, and wherein the step of forming the linear portion of the borehole comprises stabilizing the drill bit by moving the drill bit such that a portion of the formation enters the recessed cone, recessed dome, or combinations thereof to contact the bit face.

11. The method of claim 9, wherein the first plurality of cutters comprise a plurality of tungsten carbide inserts, wherein the second plurality of cutters comprise a plurality of polycrystalline diamond compact cutting elements, wherein the step of forming the curved portion of the borehole comprises removing portions of the formation with the first plurality of cutters that comprise a dimension less than that of portions of the formation removed using the second plurality of cutters to facilitate movement of the drill bit along the curved path.

12. The method of claim 8, wherein the step of forming the curved portion of the borehole comprises providing the curved portion with an angular rate of changing ranging from eight degrees to thirty five degrees per one hundred feet of length.

13. A drill bit comprising:

a bit face having an outer portion and an inner portion;

a first plurality of cutters disposed on the outer portion, wherein the first plurality of cutters are oriented to bore into a formation in a direction generally perpendicular to the bit face; and

a second plurality of cutters disposed on the inner portion, wherein the second plurality of cutters are oriented to bore into a formation in a direction generally parallel to the bit face, wherein the first plurality of cutters are adapted to engage the formation to form a curved region of a borehole, and wherein the second plurality of cutters are adapted to engage the formation to form a linear region of the borehole.

14. The drill bit of claim 13, wherein the inner portion comprises a recessed region having a height of four inches or less.

15. The drill bit of claim 13, wherein the inner portion comprises a recessed region having a height of four inches or greater.

16. The drill bit of claim 13, wherein the first plurality of cutters comprises a plurality of tungsten carbide inserts that define a leading edge that contacts the formation prior to the second plurality of cutters, wherein the leading edge adapted to crush the formation when forming a curved region of the borehole.

17. The drill bit of claim 16, wherein the second plurality of cutters comprise a plurality of polycrystalline diamond compact cutting elements adapted to cut the formation.

18. The drill bit of claim 13, further comprising a port positioned at a center of the bit face for washing the first plurality of cutters, the second plurality of cutters, or combinations thereof.

19. The drill bit of claim 17, wherein the plurality of polycrystalline diamond compact cutting elements forms a first cut in the formation having a first dimension, and wherein the plurality of tungsten carbide inserts forms a second cut in the formation having a second dimension less than the first dimension for facilitating boring of the drill bit along a curved path.

20. The drill bit of claim 13, wherein the drill bit comprises an overall length of five inches or less.

21. The drill bit of claim 13, wherein the bit face comprises a plurality of blades extending therefrom, wherein the second plurality of cutters are positioned along an inner portion of the plurality of blades, and wherein the first plurality of cutters are positioned along an outer portion of the plurality of blades, between individual blades of the plurality of blades, or combinations thereof.