Patent Application
20130146361
1. Field of the Invention
Embodiments disclosed herein relate to apparatuses and methods for drilling formation. More specifically, embodiments disclosed herein relate to apparatuses and methods for drilling formation with drilling tool assemblies having enhanced stabilizing features. More specifically still, embodiments disclosed herein relate to apparatuses and methods for drilling formation with expandable secondary cutting structure having enhanced stabilizing features.
2. Background Art
The drill string 16 includes several joints of drill pipe 16a connected end to end through tool joints 16b. The drill string 16 is used to transmit drilling fluid (through its hollow core) and to transmit rotational power from the drill rig 10 to the BHA 18. In some cases the drill string 16 further includes additional components such as subs, pup joints, etc.
The BHA 18 includes at least a drill bit 20. Typical BHA's may also include additional components attached between the drill string 16 and the drill bit 20. Examples of additional BHA components include drill collars, stabilizers, measurement-while-drilling (MWD) tools, logging-while-drilling (LWD) tools, subs, hole enlargement devices (e.g., hole openers and reamers), jars, accelerators, thrusters, downhole motors, and rotary steerable systems. In certain BHA designs, the BHA may include a drill bit 20 or at least one secondary cutting structure or both.
In general, drilling tool assemblies 12 may include other drilling components and accessories, such as special valves, kelly cocks, blowout preventers, and safety valves. Additional components included in a drilling tool assembly 12 may be considered a part of the drill string 16 or a part of the BHA 18 depending on their locations in the drilling tool assembly 12.
The drill bit 20 in the BHA 18 may be any type of drill bit suitable for drilling earth formation. Two common types of drill bits used for drilling earth formations are fixed-cutter (or fixed-head) bits and roller cone bits.
In the drilling of oil and gas wells, concentric casing strings are installed and cemented in the borehole as drilling progresses to increasing depths. Each new casing string is supported within the previously installed casing string, thereby limiting the annular area available for the cementing operation. Further, as successively smaller diameter casing strings are suspended, the flow area for the production of oil and gas is reduced. Therefore, to increase the annular space for the cementing operation, and to increase the production flow area, it is often desirable to enlarge the borehole below the terminal end of the previously cased borehole. By enlarging the borehole, a larger annular area is provided for subsequently installing and cementing a larger casing string than would have been possible otherwise. Accordingly, by enlarging the borehole below the previously cased borehole, the bottom of the formation can be reached with comparatively larger diameter casing, thereby providing more flow area for the production of oil and gas.
Various methods have been devised for passing a drilling assembly through an existing cased borehole and enlarging the borehole below the casing. One such method is the use of an underreamer, which has basically two operative states—a closed or collapsed state, where the diameter of the tool is sufficiently small to allow the tool to pass through the existing cased borehole, and an open or partly expanded state, where one or more arms with cutters on the ends thereof extend from the body of the tool. In this latter position, the underreamer enlarges the borehole diameter as the tool is rotated and lowered in the borehole.
A “drilling type” underreamer is typically used in conjunction with a conventional pilot drill bit positioned below or downstream of the underreamer. The pilot bit can drill the borehole at the same time as the underreamer enlarges the borehole formed by the bit. Underreamers of this type usually have hinged arms with roller cone cutters attached thereto. Most of the prior art underreamers utilize swing out cutter arms that are pivoted at an end opposite the cutting end of the cutting arms, and the cutter arms are actuated by mechanical or hydraulic forces acting on the arms to extend or retract them. Typical examples of these types of underreamers are found in U.S. Pat. Nos. 3,224,507; 3,425,500 and 4,055,226. In some designs, these pivoted arms tend to break during the drilling operation and must be removed or “fished” out of the borehole before the drilling operation can continue. The traditional underreamer tool typically has rotary cutter pocket recesses formed in the body for storing the retracted arms and roller cone cutters when the tool is in a closed state. The pocket recesses form large cavities in the underreamer body, which requires the removal of the structural metal forming the body, thereby compromising the strength and the hydraulic capacity of the underreamer. Accordingly, these prior art underreamers may not be capable of underreaming harder rock formations, or may have unacceptably slow rates of penetration, and they are not optimized for the high fluid flow rates required. The pocket recesses also tend to fill with debris from the drilling operation, which hinders collapsing of the arms. If the arms do not fully collapse, the drill string may easily hang up in the borehole when an attempt is made to remove the string from the borehole.
Recently, expandable underreamers having arms with blades that carry cutting elements have found increased use. Expandable underreamers allow a drilling operator to run the underreamer to a desired depth within a borehole, actuate the underreamer from a collapsed position to an expanded position, and enlarge a borehole to a desired diameter. Cutting elements of expandable underreamers may allow for underreaming, stabilizing, or backreaming, depending on the position and orientation of the cutting elements on the blades. Such underreaming may thereby enlarge a borehold by 15-40%, or greater, depending on the application and the specific underreamer design.
Typically, expandable underreamer design includes placing two blades in groups, referred to as blocks, around a tubular body of the tool. A first blade, referred to as a leading blade absorbs a majority of the load, the leading load, as the tool contacts formation. A second blade, referred to as a trailing blade, and positioned rotationally behind the leading blade on the tubular body then absorbs a trailing load, which is less than the leading load. Thus, the cutting elements of the leading blade traditionally bear a majority of the load, while cutting elements of the trailing blade only absorb a majority of the load after failure of the cutting elements of the leading blade. Such design principles, resulting in unbalanced load conditions on adjacent blades, often result in premature failure of cutting elements, blades, and subsequently, the underreamer.
Accordingly, there exists a need for apparatuses and methods of drilling formation having enhanced vibration control.
In one aspect, embodiments disclosed herein relate to a secondary cutting structure for use in a drilling assembly, the secondary cutting structure including a tubular body, and a block, extendable from the tubular body, the block including a first arrangement of cutting elements disposed on a first blade, a first stabilization section disposed proximate the first arrangement of cutting elements, a second arrangement of cutting elements disposed on the first blade, and a second stabilization section disposed proximate the second arrangement of cutting elements.
In another aspect, embodiments disclosed herein relate to a secondary cutting structure for use in a drilling assembly, the secondary cutting structure including a tubular body, and a block, extendable from the tubular body, the block including a plurality of cutting elements disposed on a first blade, and at least one depth of cut limiter disposed intermediate the apex of at least two adjacent cuttings element.
In another aspect, embodiments disclosed herein relate to a secondary cutting structure for use in a drilling assembly, the secondary cutting structure including a tubular body, and a block, extendable from the tubular body, the block including at least three blades.
In yet another aspect, embodiments disclosed herein relate to a method of drilling, the method including disposing a drilling assembly in a wellbore, the drilling assembly including a secondary cutting structure having a tubular body and a block, extendable from the body, the block including at least three blades, actuating the secondary cutting structure, wherein the actuating includes extending the block from the tubular body, and drilling formation with the extended block.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
In one aspect, embodiments disclosed herein relate generally to apparatuses and methods for drilling formation. In another aspect, embodiments disclosed herein relate to apparatuses and methods for drilling formation with drilling tool assemblies having enhanced stabilizing features. In yet another aspect, embodiments disclosed herein relate to apparatuses and methods for drilling formation with expandable secondary cutting structure having enhanced stabilizing features.
Secondary cutting structures, according to embodiments disclosed herein, may include reaming devices of a drilling tool assembly capable of drilling an earth formation. Such secondary cutting structures may be disposed on a drill string downhole tool and actuated to underream or backream a wellbore. Examples of secondary cutting structures include expandable reaming tools that are disposed in the wellbore in a collapsed position and then expanded upon actuation.
Referring now to
In the expanded position shown in
The drilling fluid flows along path 605, through ports 595 in the lower retainer 590, along path 610 into the piston chamber 535. The differential pressure between the fluid in the flowbore 508 and the fluid in the borehole annulus 22 surrounding tool 500 causes the piston 530 to move axially upwardly from the position shown in
The underreamer tool 500 may be designed to remain concentrically disposed within the borehole. In particular, the tool 500 in one embodiment preferably includes three extendable arms 520 spaced apart circumferentially at the same axial location on the tool 510. In one embodiment, the circumferential spacing would be approximately 120 degrees apart. This three-arm design provides a full gauge underreaming tool 500 that remains centralized in the borehole. While a three-arm design is illustrated, those of ordinary skill in the art will appreciate that in other embodiments, tool 510 may include different configurations of circumferentially spaced arms, for example, less than three-arms, four-arms, five-arms, or more than five-arm designs. Thus, in specific embodiments, the circumferential spacing of the arms may vary from the 120-degree spacing illustrated herein. For example, in alternate embodiments, the circumferential spacing may be 90 degrees, 60 degrees, or be spaced in non-equal increments. Accordingly, the secondary cutting structure designs disclosed herein may be used with any secondary cutting structure tools known in the art.
Referring to
Referring to
The second blade 320B of block 310 also has a third arrangement of cutting elements 340A and a fourth arrangement of cutting elements 340B. Third arrangement of cutting elements 340A are disposed at a axially distal location on blade 320B and a third stabilization section 345A is disposed proximate and axially above the third arrangement of cutting elements 340A. Second blade 320B further includes a fourth arrangement of cutting elements 340B disposed above third stabilization section 345A. Axially above the fourth arrangement of cutting elements 340B, a fourth stabilization section 345B is disposed.
Stabilization sections may be formed from various types of materials, such as tungsten carbide, diamond, and combinations thereof. In certain embodiments, stabilization sections may be formed from diamond impregnated materials. In still other embodiments, the stabilization sections may include a plurality of inserts, such as tungsten carbide inserts, diamond inserts, gauge inserts, wear compensation inserts, depth of cut limiters, and the like.
Referring to
The second blade 420B of block 410 also has a third arrangement of cutting elements 440A and a fourth arrangement of cutting elements 440B. Third arrangement of cutting elements 440A is disposed at a axially distal location on blade 420B. Fourth arrangement of cutting elements 440B is disposed on second blade 420B axially above the third arrangement of cutting elements 440A. A second stabilization section 445A is disposed proximate and axially above the fourth arrangement of cutting elements 440B.
In this embodiment, block 410 further includes a third stabilization section 450 disposed axially above first arrangement of cutting elements 430A and third arrangement of cutting elements 440A and axially below second arrangement of cutting elements 430B and fourth arrangement of cutting elements 440B. Third stabilization section 450 may extend partially or completely between first and second blades 420A and 420B.
In still further embodiments, the layout of cutting element arrangements and stabilization sections may be adjusted to optimize drilling. For example, in certain embodiments, one or more additional stabilization sections may be disposed on first blade 420A and/or second blade 420B before the first and second arrangements of cutting elements 430A and 440B, or alternatively, a stabilization second may be disposed to extend partially or completely between first and second blades 420A and 420B, similar to the third stabilization section 450, above. In still other embodiments, rather than have first and second stabilization sections 435A and 445A, reamer 400 may have a stabilization section, similar to third stabilization section 450 disposed above the second and fourth arrangement of cutting elements 430B and 440B, and extending partially or completely between first and second blades 420A and 420B.
Those of ordinary skill in the art will appreciate that by varying the relative location of cutting elements arrangements and stabilization sections, drilling dynamics may be optimized. According to the above described embodiments, the extra stabilization sections, compared to conventional reamers provide extra stabilization that may help to achieve better control of the reamer during drilling. The extra stabilization sections may further help recentralize the reamer/under-reamer with the pilot hole trajectory, thereby decreasing potentially damaging vibrations and improving drilling. Additionally, be dividing the cutting elements into additional cutting element arrangements and removing rock in stages, improved cleaning and cuttings removal may occur. Because the cleaning and cuttings removal is improved, the hydraulics around the cutting elements may be improved, thereby improving cutting element life and thus improving the efficiency of the reamer.
Referring to
Referring to
Referring to
Those of ordinary skill in the art will appreciate that the amount the blades 1505 and 1605 are offset from the bit center will depend on the specific requirements of the reaming operation. Additionally, in certain embodiments, more than three blades 1505 and 1605 may be used, for example, in alternate embodiments, four, five, or more blades 1505 and 1605 may be used. Those of ordinary skill in the art will appreciate that the number of blades 1505 and 1605 per block 1500 and 1600 may vary depending on the diameter of the reamer on which the blocks are installed. Thus, smaller diameter reamers may have blocks 1500 and 1600 carrying less blades 1505 and 1605 than relatively larger diameter reamers.
Referring to
Conventional expandable reamers included an open slot configured to receive the block when the reamer was in a compressed condition. During use, the block radially expands out of the slot into engagement with the formation, as described above. Embodiments of the present disclosure provide for a reamer having an open slot, such that in a compressed condition, the block is retracted into the open slot along with center blades 1705B and 1705C, while outer blades 1705A and 1705D are retracted into the body of the tubular, thereby allowing the reamer to be run into a wellbore. Upon actuation of the reamer, the block expands radially, thereby expanding all four blades 1705A-D into contact with the formation. As explained above, the increased diamond volume may allow for more efficient removal of rock, while the increased number of channels 1715A-C allows for efficient cleaning of the cutting structure. Those of ordinary skill in the art will appreciate that the size, i.e., length, of the expanded cutting structure may be optimized to have the most cutting elements, and thus diamond, possible while making the expanded cutting structure as short as possible, in order to provide for a more stable reamer.
Referring to
Referring to
Reamer 1900 illustrates a reamer having multiple stage reaming blades 1905. Reamer 1900 includes three areas of stabilization, 1930, 1935, and 1940. Thus, during drilling, third stabilization section 1940 contacts the wellbore wall as the first arrangement of cutting elements 1910 engages formation. As the diameter of the wellbore increases as a result of the first arrangement of cutting elements 1910 drilling the formation, second stabilization section 1935 contacts the enlarged portion of the wellbore, thereby stabilizing the reamer 1900, such that when the second arrangement of cutting elements 1915 engages the formation, cutter loading and vibrations are reduced. The second arrangement of cutting elements 1915 may then drill the formation, expanding the wellbore to a final diameter. When the diameter of the wellbore is increased to a final diameter, the first stabilization section 1930 may contact the wall of the wellbore, thereby further stabilizing the reamer 1900, further increasing the efficiency of the reaming operation.
Those of ordinary skill in the art will appreciate that in certain embodiments, reamer 1900 may have more than two stages. For example, reamer 1900 may have a third stage, wherein the third arrangement of cutting elements 1920 extends radially further than the second arrangement of cutting elements 1915. Such an embodiment may allow the diameter of the wellbore to be increased to a larger diameter in three stages. Reaming in stages allows the reamer 1900 to be stabilized at the cutting structure level, thereby reducing the magnitude of imbalance forces, damaging vibrations, and excessive cutter loading.
Referring to
After depth of cut limiters 1015 engage formation, due to wear of the cutting elements 1010, the load that would normally be placed upon the cutting elements 1010 is redistributed, and per cutter force may be reduced. Because the per cutter force may be reduced, cutting elements 1010 may resist premature fracturing, thereby increasing the life of the cutting elements 1010. Additionally, redistributing cutter forces may balance the overall weight distribution on the cutting structure, thereby increasing the life of the tool. Furthermore, depth of cut limiters 1015 may provide dynamic support during wellbore enlargement, such that the per cutter load may be reduced during periods of high vibration, thereby protecting cutting elements 1010. During periods of increased drill string bending and off-centering, depth of cut limiters 1015 may contact the wellbore, thereby decreasing lateral vibrations, reducing individual cutter force, and balancing torsional variation, so as to increase durability of the secondary cutting structure and/or individual cutting elements 1010.
As shown specifically in
Referring back to
In still other embodiments, at least one depth of cut limiter may be disposed so as to overlap with at least one cutting element. For example, depth of cut limiter 1015A may be disposed to overlap with cutting element 1010A and/or cutting elements 1010C. In certain embodiments, the overlap may be limited to a certain diameter of the cutting element. For example, the overlap may be less than fifty percent of the diameter of at least one cutting elements. In other embodiments, the overlap may be forty percent, thirty percent, twenty-five percent, twenty percent, or less.
Advantageously, embodiments of the present disclosure may provide enhanced reamer block, blade, and cutting structure design to improve the operation of the reamer. Those of ordinary skill in the art will appreciate that the above identified methods for reducing vibrations, reducing magnitude of peak torque generated during excessive weight-on-bit transfer, offsetting bending moments, and reducing excessive cutter loading may be used alone or combined.
While the present disclosure 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 may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.
