Underreamer

Claim 2

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a plurality of cutter arms; means for pivotally mounting the cutter arms on the lower body portion; means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position; latch means movable between a latching position and a release position, said latching position for latching the upper and lower bodies in the relatively longer position with the cutter arms in their retracted clearance position and the release position for permitting relative telescoping of the upper and lower bodies; means for urging the latch means towards the latching position in response to application of increased fluid pressure; and means for urging the latch means towards the release position in response to release of fluid pressure.

Claim 3

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a plurality of cutter arms; means for pivotally mounting the cutter arms on the lower body portion; means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position; and means for selectively latching the cutter arms in their retracted clearance position in response to increased pressure of drilling fluid and selectively releasing the cutter amrs for extension in response to decreased pressure of drilling fluid.

Claim 4

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a plurality of cutter arms; means for pivotally mounting the cutter arms on the lower body portion; means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position; and means for selectively latching the cutter arms in their retracted clearance position in response to increased pressure of drilling fluid and selectively releasing the cutter amrs for extension in response to decreased pressure of drilling fluid.

Claim 5

An underreamer as defined in claim 2 wherein the means for latching comprises means for preventing telescoping of the upper and lower body portions towards their relatively shorter position in response to drilling fluid pressurE.

Claim 6

An underreamer as defined in claim 3 wherein the means for preventing telescoping comprises: a sleeve on the lower body portion extending upwardly around the upper body portion; and means for preventing translation of the sleeve relative to the upper body portion.

Claim 7

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a plurality of cutter arms; means for pivotally mounting the cutter arms on the lower body portion; and means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position; and means for preventing telescoping of the upper and lower body portions towards their relatively shorter position in response to drilling fluid pressure for latching the cutter arms in their retracted clearance position, said means for preventing telescoping comprising: a sleeve on the lower body portion extending upwardly around the upper body portion; and means for preventing translation of the sleeve relative to the upper body portion, said means for preventing translation comprising: a shoulder inside the sleeve; a plurality of segments of a split ring engageable with the shoulder when the segments are in a radially extended position; means for biasing the segments relatively inwardly; and means for urging the segments radially outwardly in response to drilling fluid pressure.

Claim 8

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a plurality of cutter arms; means for pivotally mounting the cutter arms on the lower body portion; and means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position; and means for preventing telescoping of the upper and lower body portions towards their relatively shorter position in response to drilling fluid pressure for latching the cutter arms in their retracted clearance position, said means for preventing telescoping comprising: a sleeve on the lower body portion extending upwardly around the upper body portion; and means for preventing translation of the sleeve relative to the upper body portion, said means for preventing translation comprising: a shoulder inside the sleeve; a plurality of segments of a split ring engageable with the shoulder when the segments are in a radially extended position; means for biasing the segments relatively inwardly; and means for urging the segments radially outwardly in response to drilling fluid pressure.

Claim 9

An underreamer as defined in claim 5 wherein the means for urging the segments radially outwardly comprises: an axially slidable piston co-axial with the underreamer; a plurality of downwardly facing ramps on the piston; a plurality of shoes, each of the shoes being connected to a respective segment and engageable with a respective ramp on the piston; means for biasing the piston upwardly relative to the underreamer; and means for applying drilling fluid pressure to the upper end of the piston.

Claim 10

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a pair of opposed cutter arms; means for pivotally mounting the two cutter arms in scissors fashion on the lower body portion with cutter assemblies at a lower end thereof and cam followers at the upper end thereof; and means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position comprising a pair of camming surfaces on the upper body portion for camming the cam followers on the cutter arms relatively outwardly whereby the cutter assemblies are urged outwardly.

Claim 11

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a pair of opposed cutter arms; means for pivotally mounting the two cutter arms in scissors fashion on the lower body portion with cutter assemblies at a lower end thereof and cam followers at the upper end thereof; and means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position comprising a pair of camming surfaces on the upper body portion for camming the cam followers on the cutter arms relatively outwardly whereby the cutter assemblies are urged outwardly.

Claim 12

An underreamer as defined in claim 7 wherein the upper body portion comprises a plunger co-axial with the lower body portion and at least partly within the lower body portion and wherein the camming surfaces each comprise an angulated surface at the lower end of the plunger, each of said surfaces facing in the opposite direction from the other and being on opposite sides of the center line of the underreamer.

Claim 13

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position comprising a plurality of upwardly extending fingers at the upper end of the lower body portion and a plurality of downardly extending fingers on the upper body portion interlaced with the fingers on the lower body portion; a pair of opposed cutter arms; means for pivotally mounting the two cutter arms on the lower body portion in scissors fashion with cutter assemblies at a lower end thereof and cam followers at the upper end thereof; means for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position comprising a pair of camming surfaces on the upper body portion for camming the cam followers on the cutter arms relatively outwardly; and wherein the upper body portion comprises a plunger coaxial with the lower body portion and at least partly within the lower body portion and wherein the camming surfaces each comprise an angulated surface at the lower end of the plunger, each of said surfaces facing in the opposite direction from the other and being on opposite sides of the center line of the underreamer.

Claim 14

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position comprising a plurality of upwardly extending fingers at the upper end of the lower body portion and a plurality of downardly extending fingers on the upper body portion interlaced with the fingers on the lower body portion; a pair of opposed cutter arms; means for pivotally mounting the two cutter arms on the lower body portion in scissors fashion with cutter assemblies at a lower end thereof and cam followers at the upper end thereof; means for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position comprising a pair of camming surfaces on the upper body portion for camming the cam followers on the cutter arms relatively outwardly; and wherein the upper body portion comprises a plunger coaxial with the lower body portion and at least partly within the lower body portion and wherein the camming surfaces each comprise an angulated surface at the lower end of the plunger, each of said surfaces facing in the opposite direction from the other and being on opposite sides of the center line of the underreamer.

Claim 15

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a pair of opposed cutter arms; a pivot pin for pivotally mounting the two cutter arms in scissors fashion on the lower body portion with cutter assemblies at a lower end thereof and cam followers at the upper end thereof; means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position including a pair of camming surfaces on the upper body portion for camming the cam followers on the cutter arms relatively outwardly; means for conveying compressed air from the upper portion of a drill string to the lower portion of a drill string; and means for bypassing a portion of the air through the pivot pin to the cutter arms for cooling the cutter assemblies.

Claim 16

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a pair of opposed cutter arms; a pivot pin for pivotally mounting the two cutter arms in scissors fashion on the lower body portion with cutter assemblies at a lower end thereof and cam followers at the upper end thereof; means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position including a pair of camming surfaces on the upper body portion for camming the cam followers on the cutter arms relatively outwardly; means for conveying compressed air from the upper portion of a drill string to the lower portion of a drill string; and means for bypassing a portion of the air through the pivot pin to the cutter arms for cooling the cutter assemblies.

Claim 17

An earth boring underreamer comprising: an underreamer body; a plurality of cutter arms each having a cutter assembly mounted on the underreamer body for motion between a relatively retracted clearance position within the profile of the underreamer body and an extended underreaming position radially outwardly from the underreamer body; means for extending the cutter arms radially outwardly in response to compression force applied to both ends of the underreamer body; and means for selectively latching the cutter arms in the retracted position in response to application of fluid pressure irrespective of subsequent application of compression force to the ends of the underreamer body and for selectively Releasing the latching in response to relief of drilling fluid pressure.

Claim 18

An earth boring underreamer comprising: an underreamer body; a plurality of cutter arms each having a cutter assembly mounted on the underreamer body for motion between a relatively retracted clearance position within the profile of the underreamer body and an extended underreaming position radially outwardly from the underreamer body; means for extending the cutter arms radially outwardly in response to compression force applied to both ends of the underreamer body; and means for selectively latching the cutter arms in the retracted position in response to application of fluid pressure irrespective of subsequent application of compression force to the ends of the underreamer body and for selectively Releasing the latching in response to relief of drilling fluid pressure.

Claim 19

An earth boring underreamer as defined in claim 11 wherein the underreamer body comprises: an upper body portion and a lower body portion capable of axially telescoping relative to each other in response to compression force; and wherein the means for extending the cutter arms comprises means for urging the cutter arms radially outwardly in response to telescoping of the upper and lower body portions.

Claim 20

An earth boring underreamer as defined in claim 12 wherein the means for latching the cutter arms comprises means for preventing telescoping of the upper and lower body portions.

Claim 21

An underreamer for use in combination with a pilot drill comprising: an upper body portion; means for connecting the upper body portion to a drill string; a lower body portion; means for connecting the lower body portion to a pilot drill; means for connecting the upper and lower body portions together for transmitting torque therebetween and permitting limited relative axial movement between the upper and lower body portions; a plurality of cutter assemblies mounted on the underreamer for movement between a retracted position within the profile of the upper and lower body portions and an extended position outside the profile of the upper and lower body portions; and means for urging the cutter assemblies towards their extended position in response to relative shortening of the axial length of the underreamer in response to axial compression externally applied to the underreamer.

Claim 22

An underreamer for use in combination with a pilot drill comprising: an upper body portion; means for connecting the upper body portion to a drill string; a lower body portion; means for connecting the lower body portion to a pilot drill; means for connecting the upper and lower body portions together for transmitting torque therebetween and permitting limited relative axial movement between the upper and lower body portions; a plurality of cutter assemblies mounted on the underreamer for movement between a retracted position within the profile of the upper and lower body portions and an extended position outside the profile of the upper and lower body portions; and means for urging the cutter assemblies towards their extended position in response to relative shortening of the axial length of the underreamer in response to axial compression externally applied to the underreamer.

Claim 23

An underreamer as defined in claim 14 further comprising means for inhibiting relative axial shortening of the underreamer in response to increased drilling fluid pressure.

Claim 24

An underreamer as defined in claim 14 wherein the cutter assemblies mounted on the underreamer comprise: a pair of cutter arms; a cutter mounted on the lower end of each of the arms; and a pivot pin extending transverse to the axis of the underreamer, said cutter arms both being mounted on said pivot pin in scissors fashion; and wherein the means for urging comprises means for camming the upper portions of the respective cutter arms away from each other.

Claim 25

An underreamer comprising: an elongated hollow lower body having a spline at its upper end; a pivot pin extending transverse to the tool body; a pair of cutter arms mounted on the pivot pin for pivoting in scissors fashion between a retracted position with an outer profile within the profile of the lower body and an extended position beyond the profile of the body, each of said cutter arms including a cutter assembly at its lower end below the pivot pin and a cam follower portion at its upper end above the pivot pin; an elongated upper body co-axial with the lower body and having a spline at its lower end mated with the spline on the upper end of the lower body for transmitting torque therebetween, and means at its upper end for connecting the upper body to a drill string, said lower body being axially translatable relative to the upper body between a lower ''''closed'''' position and an upper ''''open'''' position; cam means connected to the upper body and extending into the hollow lower body, said cam means having a pair of oppositely facing cam surfaces for engaging the cam follower portions of the respective cutter arms and camming them relatively outwardly upon upward translation of the lower body relative to the upper body; and means for limiting downward translation of the lower body relative to the upper body.

Claim 26

An underreamer comprising: an elongated hollow lower body having a spline at its upper end; a pivot pin extending transverse to the tool body; a pair of cutter arms mounted on the pivot pin for pivoting in scissors fashion between a retracted position with an outer profile within the profile of the lower body and an extended position beyond the profile of the body, each of said cutter arms including a cutter assembly at its lower end below the pivot pin and a cam follower portion at its upper end above the pivot pin; an elongated upper body co-axial with the lower body and having a spline at its lower end mated with the spline on the upper end of the lower body for transmitting torque therebetween, and means at its upper end for connecting the upper body to a drill string, said lower body being axially translatable relative to the upper body between a lower ''''closed'''' position and an upper ''''open'''' position; cam means connected to the upper body and extending into the hollow lower body, said cam means having a pair of oppositely facing cam surfaces for engaging the cam follower portions of the respective cutter arms and camming them relatively outwardly upon upward translation of the lower body relative to the upper body; and means for limiting downward translation of the lower body relative to the upper body.

Claim 27

An underreamer as defined in claim 17 further comprising means for latching the lower body in its lower ''''closed'''' position in response to fluid pressure in the drill string.

Claim 28

An underreamer as defined in claim 18 wherein the means for latching comprises: a sleeve on the lower body extending upwardly around the lower body; and means foR preventing translation of the sleeve relative to the upper body.

Claim 29

An underreamer as defined in claim 19 wherein the means for preventing translation comprises: a shoulder inside the sleeve; a plurality of segments of a split ring engageable with the shoulder when the segments are in a radially extended position; means for biasing the segments radially inwardly; a plurality of shoes, each of the shoes being connected to a respective segment; an axially slidable piston co-axial with the underreamer; a plurality of downwardly facing ramps on the piston, each of said ramps being engageable with a respective one of the shoes; means for biasing the piston relatively upwardly; and means for applying drilling fluid pressure to the upper end of the piston for urging it downwardly.

Claim 30

An underreamer as defined in claim 17 further comprising: means for conveying compressed air from the upper body through the lower body; and means for bypassing a portion of the air through the pivot pin to the cutter arms for cooling the cutter assemblies.

Claim 31

A latching selector sub comprising: an elongated housing; a piston axially slidable in the housing from an upper position towards a lower position in response to fluid pressure; means for biasing the piston towards its upper position; a sleeve around at least a portion of the housing and axially slidable relative thereto between a lower position and an upper position; stop means mounted in the housing for preventing sliding of the sleeve towards its upper position; and means for moving the stop means radially relative to the housing in response to moving of the piston.

Claim 32

A latching selector sub comprising: an elongated housing; a piston axially slidable in the housing from an upper position towards a lower position in response to fluid pressure; means for biasing the piston towards its upper position; a sleeve around at least a portion of the housing and axially slidable relative thereto between a lower position and an upper position; stop means mounted in the housing for preventing sliding of the sleeve towards its upper position; and means for moving the stop means radially relative to the housing in response to moving of the piston.

Claim 33

A latching selector sub as defined in claim 22 wherein downward movement of the piston in response to fluid pressure cams the stop means radially outwardly for preventing sliding of the sleeve.

Claim 34

An underreamer as defined in claim 23 wherein the stop means comprises: a plurality of segments of a split ring engageable with the sleeve when the segments are in a radially extended position; and means for biasing the segments relatively inwardly.

Claim 35

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a plurality of cutter arms; means for pivotally mounting the cutter arms on the lower body portion; means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position; sleeve means on the lower body portion extending upwardly around the upper body portion; an upwardly facing shoulder on the sleeve means; a downwardly facing shoulder on the upper body portion opposed to the upwardly facing shoulder; a plurality of members movable between an extended position in between the shoulders and a retracted position removed from between the shoulders; means for resiliently biasing the members towards the retracted position; and means for urging the members towards the extended position in response to drilling fluid pressure.

Claim 36

A weight actuated underreamer comprising: a lower body portion connectable to a lower portion of a drill string; an upper body portion connectable to an upper drill string; means interconnecting the upper and lower bodies for transmitting torque therebetween and permitting telescoping of the lower and upper bodies between a relatively longer position and a relatively shorter position; a plurality of cutter arms; means for pivotally mounting the cutter arms on the lower body portion; means on the upper body portion for urging the cutter arms relatively outwardly towards an extended underreaming position when the upper and lower bodies are telescoped towards the relatively shorter position and for permitting the cutter arms to retract relatively inwardly to a clearance position when the upper and lower bodies are telescoped towards the relatively longer position; sleeve means on the lower body portion extending upwardly around the upper body portion; an upwardly facing shoulder on the sleeve means; a downwardly facing shoulder on the upper body portion opposed to the upwardly facing shoulder; a plurality of members movable between an extended position in between the shoulders and a retracted position removed from between the shoulders; means for resiliently biasing the members towards the retracted position; and means for urging the members towards the extended position in response to drilling fluid pressure.

Claim 37

An underreamer comprising: a tool body including means at its lower end for connection to a lower portion of a drill string and means at its upper end for connection to an upper drill string; a pivot pin in the tool body transverse to the length thereof; an axial bore in the pivot pin; a cutter arm mounted on the pin for pivotinG between an extended underreaming position and a retracted clearance position; a cutter assembly on the cutter arm; a passage through the cutter arm to the vicinity of the cutter assembly and in fluid communication with the axial bore in the pin; and means for delivering drilling fluid to the axial bore.

Claim 38

An underreamer comprising: a tool body including means at its lower end for connection to a lower portion of a drill string and means at its upper end for connection to an upper drill string; a pivot pin in the tool body transverse to the length thereof; an axial bore in the pivot pin; a cutter arm mounted on the pin for pivotinG between an extended underreaming position and a retracted clearance position; a cutter assembly on the cutter arm; a passage through the cutter arm to the vicinity of the cutter assembly and in fluid communication with the axial bore in the pin; and means for delivering drilling fluid to the axial bore.

Claim 39

An underreamer as defined in claim 26 further comprising a bypass fluid passage between the upper and lower connection means past the axial bore so that a portion of drilling fluid can flow through the bypass passage and a portion can flow through the axial bore.

Claim 40

An underreamer as defined in claim 26 further comprising: a second cutter arm mounted on the pivot pin for pivoting between an extended underreaming position and a retracted clearance position; a cutter assembly on the cutter arm; and a fluid passage through the second cutter arm to the vicinity of the cutter assembly and in fluid communication with the axial bore in the pin; each of said cutter arms including a camming portion on the opposite side of the pivot pin from the respective cutter assembly; said underreamer further comprising: cam means in the tool body for camming the cutter arms towards the extended underreaming position.

Claim 41

An underreamer as defined in claim 10 wherein the means for bypassing comprises an axial bore in the pivot pin and a fluid passage through each of the cutter arms to the vicinity of the respective cutter assembly and in fluid communication with the axial bore in the pivot pin.