Adjustable body supported cutter arms for underreamer

Abstract

An underreamer for connection with a rotary pipe string includes inner and outer body sections which form a body structure to provide a fluid flow path therethrough for communicating with piston and cylinder means formed between the body sections for receiving drilling fluid to effect telescopic movement between the body sections permitting engagement of cutter arms and support of said cutter arms on the outer body of the underreamer utilizing a slideable, non-pivoting stop block. Cutter arms are pivotally mounted on the inner body section and, upon engagement of the cutter arms to effect underreaming are fully supported on the outer body section thereby minimizing damage from vibration and repeated use on the threaded inner body sections.

Claims

1. An improved underreamer cutter arm assembly comprising: a cutter arm providing a lateral slot on at least one side of the cutter arm and one or more cutter elements on a distal end of the cutter arm; a moveable yoke assembly engaging an interior surface of an underreamer comprised of an upper body connected to a lower body, pinned to a proximal end of the cutter arm, and a non-pivoting stop block slideably engaged on an interior surface of the underreamer comprised of an upper body connected to a lower body positioned between the cutter arm and an outer surface of the underreamer; whereby the slideable, non-pivoting stop block abuts a shoulder of the underreamer upon full extension of the cutter arm from the underreamer transferring all mechanical forces acting on the cutter arm to the stop block and the underreamer.

2. The cutter arm of claim 1 wherein the slideable, non-pivoting stop block is elongated to shorten the extension of the cutter arm from a lateral surface of the underreamer comprised of an upper body connected to a lower body.

3. The cutter arm of claim 1 wherein the slideable, non-pivoting stop block is shortened to increase the extension of the cutter arm from a lateral surface of the underreamer comprised of an upper body connected to a lower body.

4. An improved underreamer, comprising: a fluid flow path through a body structure including an inner body moving telescopically within an outer body, comprised of an upper body connected to a lower body, section having circumferentially spaced, longitudinal slots for receiving cutter arms and one or more moveable cutter arms cooperatively engaged with a projection for selective movement of the cutter arms in the outer body section to pivotally support the cutter arms in the longitudinal slots of the outer body; a yoke on the inner body section pivotally connected to the one or more moveable cutter arms and slideably engaging one or more field replaceable, slideable and non-pivoting stop blocks; and, a fluid actuated piston to move the inner body section, moving the one or more cutter arms between the cooperatively engaged projection and the grooves to expand the cutter arms outwardly of the outer body section and to seat the slideable, non-pivoting stop block against the telescopic outer body.

5. The improved underreamer of claim 4 wherein a plurality of field-replaceable stop blocks adjustably limit a telescopic movement of the body sections providing a range of hole enlargement diameters attainable with the underreamer.

6. A field-installable underreamer slideable, non-pivoting stop block slideably engaged between an internally sliding yoke and an articulated underreamer arm comprising: an upper face adapted to fully engage an outer telescopic body of an underreamer comprised of an upper body and a lower body upon extension of an underreamer arm; and, an arcuate lower face adapted to fully engage a corresponding proximal edge surface of the underreamer arm upon movement of the underreamer arm by a yoke wherein force experienced by the cutter arm during underreaming is supported by the slideable, non-pivoting stop block in full engagement with the outer telescopic body of the underreamer.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a longitudinal sectional view illustrating a preferred embodiment of the bore hole enlarger with the cutter arms in retracted position.

(2) FIG. 2 is a sectional view of the tool with the cutter arm in the extended position.

(3) FIG. 3 is a sectional view on the line 3-3 of FIG. 1 to better illustrate certain structural details.

(4) FIG. 4 is a sectional view on the line 4-4 of FIG. 1 to illustrate an embodiment of the cooperative means on the outer body section and the cutter arms.

(5) FIG. 5 is a sectional view on the line 5-5 of FIG. 1 to illustrate an embodiment of the cooperative means on the outer body section and the cutter arms.

(6) FIG. 6 is an end view of the stop block;

(7) FIG. 7 is a perspective side view of the stop block showing the inner railed slot; and,

(8) FIG. 8 is a top perspective view of the stop block.

DETAILED DESCRIPTION OF THE INVENTION

(9) FIG. 1 shows the underreamer of the present invention in the closed or relaxed position. FIG. 2 shows the underreamer of the present application in the energized position with the cutter arm engaging a well bore WB.

(10) Directing our attention to the underreamer shown in FIG. 1, the upper tubular body 10 provides a bore 14 allowing hydraulic communication through the upper body 10 from a drillstring (not shown) which is threaded to the upper male threads 12 of upper body 10. Upper body 10 also provides a counterbore section 16 into which is fitted upper tube assembly 26 providing a set of hydraulic seals 44 to provide a dynamic seal on the tube in the counter-bored section 16 of the upper body 10.

(11) FIG. 1 also shows a threaded connection means 12 on upper body 10 allowing connection in a drill string (not shown) and permitting the flow of drilling fluid through the upper tube assembly 26 through longitudinal passage 14. Upper body 10 is counter-bored 16 to provide a means for inner body, shown generally at 9, to move longitudinally in the upper body 10 and lower body 20 in the following manner.

(12) The upper piston of the tube assembly 26 engages an interior wall of an annular sleeve 29 inserted in an upper threaded throat 27 of the lower body 20. This sleeve 29 portion is held in a fixed position in the lower body 20 by set screw 29a. Counterbore 16 also provides chamber 18 with fluid passage 22, enclosing a spring 23 which provides resistance to the extension movement of the inner body when pump pressure is increased and fills the space 28 through the port 24 to move the cutter arm 32 into engagement with the well bore for underreaming.

(13) Tube assembly 26 provides a passage 24 to chamber 28 to provide hydraulic pressure from a longitudinal passage 14 to move the piston assembly connected to yoke 30 and cutter arm 32. Yoke 30 provides a rail permitting movement of stop block 34. Stop block 34 has a complementary slot for relative movement on yoke 30. Yoke 30 is threadedly connected to tube assembly 26 by threaded connection 38 and is prevented from loosening by set screw 40. Dynamic seals 42, 44, and 46 are provided between the hydraulically sealed tubes 26, 36 to seal the tube assembly within the assembled underreamer body 10, 20. The cutter arm assembly 32 has a slot 48 into which is assembled a cam 50 retained in the body by pin or other means 52 to thereby permit relative lateral cutter arm 32 movement thereby engaging the cutter elements 54 on a distal end outward of the body 20 on a wellbore (not shown in FIG. 1). Lower tube assembly 36 is seated on shoulder 35 onto which is placed upper tube 26 which are then affixed to the yoke assembly 30 by set screw 40 to prevent disengagement of the inner body assembly 9. Seal bushing assembly 46 is mounted in the distal end to support the dynamic sealing elements and is retained thereon by a snap ring 47 or other device, all in a manner well known in this art.

(14) As further shown in FIG. 1, inner body 9 comprised of an assembly providing a bore 17 communicating from the interior diameter 14 of an underreamer, comprised of an upper body 10 connected to lower body 20, providing a jetting nozzle 100 in a manner well known in this art and providing hydraulic pressure on the drill bit or motor which are normally found on the distal end of the drill string.

(15) FIG. 2 is another view of the improved underreamer of the present application showing the cutter arm in extension after pump pressure has moved the inner body up and caused each arm to move outwardly of the body. All of the structure shown in FIGS. 1 and 2 are described in U.S. Pat. No. 4,614,242, with the exception of the cooperating stop block 34 with the upper body 10 connected with lower body 20 to form the outer body of the underreamer. As shown in FIG. 2, an increase in pump pressure moves the piston arrangement, i.e. the top 26 of the inner body or tube assembly 9 providing a dynamic seal 45a between the outer diameter of the inner body 9 and the inner diameter of the sleeve portion 29, having lower seal 45.

(16) As may be readily appreciated, increased pump pressure moves drilling mud from the inner longitudinal bore 17 through port 24 into the space 28 moving the piston upward and compressing resilient member 23. This action moves yoke 30 drawing the stop block 34 across the unencumbered space 62, as seen in FIG. 1, into engagement with the shoulder 60 of lower body 20 which together with upper body 10 forms the outer body of the underreamer. FIG. 2 also shows the relative movement of the pin 66 from the relaxed or unextended position and pin 68 of the extended position of the cutter arm 32 yoke assembly 30.

(17) FIG. 3 is a cross-sectional view of the stop blocks 34, shown on FIG. 1 at line 3-3, showing lower tube 36 providing passage 17 and yoke 30 on which each stop block 34 is slideably engaged. FIG. 3 also more clearly shows the relative distribution of the stop block assemblies 34 on each rail of the yoke assembly 30.

(18) FIG. 4 is a cross-sectional perspective through the view, shown in FIG. 1 at line 4-4, providing a view of the relative location of the cams 50 in grooves on each cutter arm 32 fitting around the central passage 36 to permit relative outward movement of the cutter arm assembly 32. Each side of the cam 50 is either provided with a pin 50a for engaging the underrreamer body 20 or another method of fixing of said cam in said groove by means well known in the trade at 52.

(19) FIG. 5 is a cross-sectional view of the pivot pin 66 and stop block 34 connection through the line 5-5 shown in FIG. 1 detailing the eccentric screws 70 which retain the pivot pins 66 in each cutter arm assembly 32. Each screw 70 is retained in the body with a snap ring 72. Tube 36 provides a fluid passageway 17 through the yoke assembly 30.

(20) FIG. 6 is an end view of the stop block assembly 34 of the present embodiment showing the slot 600 running through the body 34 permitting slideable engagement with a rail on each portion of the yoke (not shown) and providing a shoulder 608 for engaging the yoke (not shown) and the stop block 34 in slideable engagement. The narrow portion of yoke 30 is affixed to the stop block 34 through the passageway 606. Stop block 34 also provides an upper surface 602 having a bevel 604 for conformity of the circular profile of the underreamer body 20.

(21) FIG. 7 is a side view of the stop block assembly 34 of the present embodiment showing the arcuate shaped lower end 614. The figure shows a side view of the stop block 34 having a lower surface profile 614 which accommodates the end of cutter arm (not shown) and which, upon movement of the stop block 34 in the lower body (not shown, but shown as 20 in FIGS. 1 and 2), engages the upper end 612 with the body (not shown, but shown as 20 in FIGS. 1 and 2). Lower profile 614 is designed to fully support the end of cutter arm (not shown, but more fully shown as 32 in FIGS. 1 and 2) in its extended position upon movement of the stop block 34 into contact with the outer body (not shown, but shown as 10 and 20 in FIGS. 1 and 2) at face 612 on the upper end of the stop block 34. Bevels 610 are provided on the upper end of stop block 34 to allow movement of the stop block 34 into full flush engagement with the upper body 20 shoulder at 60, as shown in FIGS. 1 and 2. The stop block is shaped to accommodate the pivot pin assembly (not shown in this view, but shown as 66 and 68 in FIGS. 1 and 2) and the movement of the cutter arm (not shown) outward from the body 20 to hold the cutter arm in full engagement with the well bore (not shown).

(22) The flattened, shaved or beveled 604 exterior surface 602 allows the stop block 34 to conform with the circular profile of the underreamer body (not shown). The inner slot shown in the dashed area 600, 606 engages a rail (not shown) on the yoke assembly to slideably move and retain the stop block during operation within the underreamer body as previously described.

(23) FIG. 8 is a top view of the stop block assembly 34 of the present embodiment showing in the dashed areas, the inner rail slot location 600a, 606a cut through the stop block 34 and slideably engaging the rail on the yoke assembly as previously described. FIG. 8 also shows the upper surface 602, the bevels 610 on the upper surface 612 as previously described and the lower surface 614 for engagement of the end of the cutter arms, all as previously described.

(24) The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.