Abstract:
The invention consists of the shape and design of plural pairs of cutter blades for use in rotary tubing tools which cutter blades have specialized shapes and cutting surfaces for performing certain specific downhole cutting operations adjacent a tubing string.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to cutter blades for use in rotary tubing tools and, more particularly, but not by way of limitation, it relates to specific ones of improved cutter blades having configurations and hardened surfaces that are particularly adapted for specific grinding, milling and/or cutting attitudes relative to the tubing string. 
     2. Description of the Prior Art 
     Prior art cutter blades have been utilized with &#34;through-tubing&#34; tools for clean-out, cable cutting, tubing cutter function, etc., and such cutting blades are available from such as Kat Tool, Inc. of New Iberia, La. These cutter blades are hardface reinforced with tungsten carbide surfaces and such tools are available in a number of diametric sizes for accommodation in selected tubing dimension. These tools were generally constructed of knife-like configuration. U.S. Pat. No. 3,050,122 in the name of Hewitt et al. discloses a rather heavier duty rotary tool that carries two sets of cutters, an upper set may be actuated so that the cutter blades extend outward radially and cut the casing while a second set of lower cutter blades function to notch the formation below the point where the casing was separated. 
     The U.S. Pat. No. 2,284,170 illustrates a downhole oil well tool wherein a pair of cutting blades are actuated by fluid pressure into cutting position, whereupon induced rotation of the tool will enable a circular cutting action. U.S. Pat. No. 2,822,150 teaches still another form of rotary, expansible drill bit of the reamer type which may be utilized to enlarge a borehole annulus. Here again, the expansible cutters may be extended hydraulically in response to pressure of drilling fluid that is being circulated down through the tool. 
     The prior art relating most directly to expansible blades for rotary tubing tools is well characterized in applicant&#39;s previously filed U.S. Pat. No. 4,809,793 as issued on Mar. 7, 1989. This patent describes a rotary clean-out tool of the type that could use the cutting blades that are described in the present application. Thus, the tubing clean-out tool may include fluid pressure responsive linear actuators that function above the cutting blade assemblies to expand and retract the blade to operational attitude. Also, the present cutter blades may function in combination with another fluid pressure-responsive, linear actuator which is the subject matter of a patent application entitled &#34;AN IMPROVED DOWNHOLE CUTTING TOOL&#34;, Ser. No. 07/815,327, and filed concurrently herewith. 
     Finally U.S. Pat. No. 1,494,274 discloses a blade configuration that is of the same general type as Applicant&#39;s expansible blades, these blades being used in a coal cutting machinery. U.S. Pat. No. 4,431,065 discloses an underreamer blade having isolated hardness features suitable for specific cutting attitudes. 
     SUMMARY OF THE INVENTION 
     The present invention relates to improvements in construction of expansible cutting blades that function in pairs within a particular type of rotary tubing tool having two-way thrust control over the expansion of the cutting blades. That is, a hydraulic actuator from above the blades as well as a hydraulic actuator from below the blades forces their respective piston rod ends into contact with the cutting blades thereby to position cutting surfaces of the blades outward into contacting relationship with a surrounding debris formation or other deposit that is being removed. Several specific cutting blade pairs are disclosed, each having different hardness characteristics and configurations, and each being disposed for cutting and/or milling in a particular attitude relative to the tubing tool. 
     Therefore, it is an object of the present invention to provide cutting tool blades that are suitable for upward reaming movement along a tubing section. 
     It is also an object of the present invention to provide a pair of elbow blades for use in cutting and reaming out within a tubular section. 
     It is still further an object of the present invention to provide a cutting and milling head consisting of a pair of opposed blades suitable for cutting and grinding cut tubing sections. 
     Finally, it is an object of the present invention to provide a pair of cutting blades that form a downward reaming head for cutting waste material and buildup along a diameter slightly larger than the tubing section. 
     Other objects and advantages of the invention will be evident from the following detailed description when read in conjunction with the accompanying drawings which illustrate the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an idealized view in vertical section of a rotary tubing tool of the type having both downward and upward acting linear actuators for expanding and reinforcing the expansible cutting blades shown here as fan-type blades in the closed position; 
     FIG. 2 is a side view of the fan-type blades in the open position; 
     FIG. 3 is an upper end view of the fan-type blades of FIG. 2; 
     FIG. 4 is a plan view of elbow-type cutting blades when in the closed position; 
     FIG. 5 is a plan view of the elbow-type cutting blades when in the open or expanded position; 
     FIG. 6 is a plan view of cutter/miller blades when in the closed position; 
     FIG. 7 is a plan view of the cutter/miller blades when in the open position; 
     FIG. 8 is a plan view of a pair of reamer blades when in the closed position; and 
     FIG. 9 is a plan view of the downward reamer blades when in the open position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a rotary tubing tool 10 of a type that can utilize the expandable blades of the present invention. While only a portion of the rotary tubing tool 10 is shown in idealized form, the complete design is the subject matter of a co-pending U.S. application entitled An Improved Downhole Cutting Tool which is filed concurrently herewith. The rotary tubing tool 10 may normally be used in series with such as a positive-displacement motor which is commercially available to selected specifications from SlimDril, Inc. of Houston, Tex. Also, the bottom end of rotary tubing tool 10 may include additional substructure such as, e.g., a drill or milling head of selected type. 
     The tubing tool 10 includes a cylindrical body 12 having an axial bore 14 and counterbore 16 slidably receiving a respected piston 18 and piston rod end 20. In like manner, the lower portion of tubing tool 10 includes an axial bore 22 and counterbore 24 which slidably receive a respective piston 26 and piston rod end 28. Intermediate the tool body 12 is a narrow, transverse slotway or cavity 30 extending between a bearing surface 32 of piston rod end 20 and a generally peaked or pointed end 34 of piston rod end 28. 
     A pair of cutter blades 36a and 36b having respective pivot holes 38a, 38b are aligned for retention on a pivot pin 40, such individual blades 36a, 36b being disposed in opposed, rotational relationship. Thus, in response to a predetermined fluid pressure in counterbore 14, piston 18 is moved downward. Rod end 20 and contact surface 32 move downward in contact with respective angle edges 42a, 42b tending to separate the blade corner blocks 44a, 44b. Successively, drilling fluid pressure from above is applied via longitudinal porting (not shown) within lower bore 22 to force piston 26 upward such that piston rod end 28 and conical bearing surface 34 contact the lower angle edges 54a and 54b of blades 34a, 34b tending to spread them further outward to their fullest expandable movement, as shown in FIG. 2. Thus, piston rod ends 20 and 28 are actuated downward and upward, respectively, to spread the cutter blocks 46a and 46b fully outboard as shown in FIG. 2. 
     In the interest of clarity, the tubing tool 10 of FIG. 1 is shown in idealized form with a minimum of structure defined. Thus, the manner in which the pressurized drilling fluid is ported from the upper axial chamber down to the lower extremities of tubing tool 10, and the manner in which various sealing and piston control aspects of the invention are achieved, is fully set forth in the co-pending U.S. patent application entitled An Improved Downhole Cutting Tool as well as Applicant&#39;s prior U.S. Pat. No. 4,809,793. The present application is directed to the various cutting plate pairs which function in similar manner when installed in such as the rotary tubing tool 10. 
     Referring to FIG. 2 and 3, the pair of cutting blades 36a, 36b are aligned in open configuration, i.e., the cutting attitude. The cutting blades 36a, 36b, known as a fan-type cutting blade, are configured for upward cutting of a concentric area immediately adjacent the outer skin or surface of cylindrical body member 12. 
     The cutting blade 36a consists of a planar body member 48a having upper angle edge 42a which extends perpendicularly to an outer edge 50a extending to terminus 52a. From terminus 52a the plate 48a extends an acute angular edge 54a that once again joins upper angle edge 42a. Cutter blades 46a and 46b are rigidly secured to extend outward from outer edges 50a and 50b. In fact, as shown in FIG. 3, two such cutter blades extend outward on each side as cutter blocks 46a and 47a are rigidly secured in parallel as are the opposite side cutter blocks 46b and 47b. Hardfacing material in the form of tungsten carbide inserts 56, e.g., KUTRITE™ inserts, are affixed in inset along the right turn-oriented side of the cutter blocks 46 and 47. The tungsten carbide insert 56 array is such that a cutting interface will exist at both the tops of cutter blocks 46, 47 and the outer edges. Note too that when blades 36 a, 36b are fully expanded outward, a corner block 44b abuts against angular edge 58a. In like manner, a corner block 44a (see FIG. 3) abuts against a similar edge 58b on the opposite side. 
     FIGS. 4 and 5 show a pair of elbow-type cutter blades 60a and 60b. Each of the cutter blades 60a and 60b is formed with an upper angle edge 62a, 62b extending into an outer edge 64a, 64b which further joins an elbow surface 66a, 66b. Adjacent elbow surface 66a, 66b is a foot edge 68a, 68b which extends through a terminus 70 to an inner edge 72a, 72b which returns to the upper angle edge 62a, 62b. A pivot hole 74a, 74b is formed through each cutting blade. A corner block 76a, 76b is formed at the joinder of the upper angle edge to the inner edge 72a, 72b. 
     The elbow surfaces 66a and 66b are adapted to ride around an inner diameter wall in non-abrasive manner; therefore, the elbow surfaces 66 each has flush-mounted inlaid synthetic diamond 78a, 78b, i.e., the thermally stable polycrystalline diamond material. The outer edges 64a, 64b are each inset with such as a block of tungsten carbide alloy as block 80a, 80b are inset and secured with such as silver solder. Similarly, the foot edges 68a, 68b are formed with insert blocks 82a, 82b matrices containing natural diamond arrays. 
     In operation, the cutter blades 60a, 60b may be employed for reaming out casing, liner or the like with either upward or downward motion as elbow surfaces 66a, 66b will seek a position adjacent the inside wall of the tubular goods while the grinding and abrading cutting action continues: 
     It should be understood that the hard-facing types may be selected from a number of well-known types of material. Such materials as synthetic diamond, natural diamond, tungsten carbide hardened steel, KUTRITE™, etc. may be employed variously as design choices dictate. 
     Referring now to FIGS. 6 and 7, a pair of cutter blades 90 each consist of an upper angle edge 92, a corner 94 extending into an outer edge 96 and terminating in an outwardly turned terminus toe 98. From terminus toe 98 the shape proceeds through a lower rounded foot 100 and a returning acute angle edge 102 which continues through corner 104 and back to the upper angle edge 92a, 92b. A corner abutment 106 is formed at corner 104a, 104b to provide interlocking juncture between adjacent edges 94a and 106b and 106a and 94b when blades 90a, 90b are fully open about the pivot hole 108. 
     The corner 106a, 106b and the raised toe portion 110 are approximately twice as thick as the blade portion 112 such that the blades function in plier-type seating about pivot holes 108. Hardfacing such as the tungsten carbide inserts 112 are placed around the outer edge of blades 90 as at edge 96a, 96b, toe 98a, 98b and foot 100a, 100b at the right turn contacting surfaces. 
     In operation, the cutter blades 90 are employed when it is desired to cut the casing by cutting through the inner wall outward and milling any deposits and casing debris immediately therebelow. The outer point of the toe 98a, 98b is an effective tubing cutter as foot edge 100b provides milling contact. 
     FIGS. 8 and 9 illustrate a pair of downward reamer blades 120 which function to ream deposits away from the tubing tool in a downward direction relative thereto. The blades 120 each pivot about a pivot hole 122 between the withdrawn position (FIG. 8) and the interlock position (FIG. 9). Each blade includes thickened corner blocks 124 and 126 which lock in abutment with respective corner edge 128 and acute angle edge 130. Upper angle edges 132 provide contact for the downward-bearing piston member to effect outward spreading of the blades to operational condition. Simultaneously, the lower acute angle edges 130a, 130b are contacted by the upward-bearing piston (see FIG. 1). Each of blades 120a, 120b includes a lowermost foot pad 134 that is inset with rows of natural diamond 136. The foot pads 134a are preformed with the natural diamond set in a selected hardened steel alloy. 
     Changes may be made in the combination and arrangement of elements as heretofore set forth in the specification and shown in the drawings; it being understood that changes may be made in the embodiments disclosed without departing from the spirit and scope of the invention as defined in the following claims.