Reverse circulation expansible rotary drill bit with hydraulic lock

Claim 2

In a rotary drill bit for attachment to a drill string to be rotated thereby in a borehole: a main body, laterally movable cutter means carried by said body, means for expanding said cutter means laterally of said body from a retracted position to an expanded position, and means for releasably retaining said cutter means in one of said positions comprising means providing a hydraulic fluid chamber and a passage leading from said chamber, a hydraulic fluid filling said chamber, and releasable means for closing said passage to trap said hydraulic fluid in said chamber to retain said cutter means in saId one of said positions and to prevent additional fluid from entering said chamber, said closing means being movable from its passage closing position.

Claim 3

In a rotary drill bit as defined in claim 1; wherein said releasable retaining means traps said hydraulic fluid in said chamber to retain said cutter means in a retracted position.

Claim 4

In a rotary drill bit as defined in claim 1; said expanding man means comprising a mandrel movable longitudinally within and relative to said body.

Claim 5

In a rotary drill bit as defined in claim 1; said expanding means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means responsive to fluid under pressure in the borehole for effecting expansion of said cutter means.

Claim 6

In a rotary drill bit as defined in claim 1; said expanding means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means responsive to fluid under pressure in the borehole for effecting expansion of said cutter means, cylinder and piston means together with said body and mandrel providing said hydraulic fluid chamber.

Claim 7

In a rotary drill bit for attachment to a drill string to be thereby in a borehole: a main body, laterally movable cutter means carried by said body, means for expanding said cutter means laterally of said body from a retracted position to an expanded position, and expanded for releasably retaining said cutter means in one of said positions comprising means providing a hydraulic fluid chamber and a passage leading from said chamber, and releasable means for closing said passage to trap hydraulic fluid in said chamber to retain said means in said one of said positions, said closing means being movable from its passage closing position; wherein said releasable retaining retains said cutter means in a retracted position, said body and mandrel providing cylinder and piston means responsive to fluid under pressure in the borehole annulus surrounding the drill string for effecting expansion of said cutter means.

Claim 8

In a rotary drill bit for attachment to a drill string to be thereby in a borehole: a main body, laterally movable cutter means carried by said body, means for expanding said cutter means laterally of said body from a retracted position to an expanded position, and expanded for releasably retaining said cutter means in one of said positions comprising means providing a hydraulic fluid chamber and a passage leading from said chamber, and releasable means for closing said passage to trap hydraulic fluid in said chamber to retain said means in said one of said positions, said closing means being movable from its passage closing position; wherein said releasable retaining retains said cutter means in a retracted position, said body and mandrel providing cylinder and piston means responsive to fluid under pressure in the borehole annulus surrounding the drill string for effecting expansion of said cutter means.

Claim 9

In a rotary drill bit adapted for attachment to a drill string to be rotated thereby in a borehole: a main body; laterally expansible cutter means carried by said body; means engageable with said cutter means and responsive to fluid pressure in the borehole annulus surrounding the drill string for expanding said cutter means laterally outwardly of said body; and releasable lock means for initially preventing expansion of said cutter means.

Claim 10

In a rotary drill bit adapted for attachment to a drill string to be rotated thereby in a borehole: a main body; laterally expansible cutter means carried by said body; means engageable with said cutter means and responsive to fluid pressure in the borehole annulus surrounding the drill string for expanding said cutter means laterally outwardly of said body; and releasable lock means for initially preventing expansion of said cutter means.

Claim 11

In a rotary drill bit as defined in claim 7; said releasable lock means including means providing a hydraulic fluid chamber and a port leading from said chamber, and valve means for initially closing said port, said valve means being shiftable to a position opening said port.

Claim 12

In a rotary drill bit as defined in claim 7; said expanding means for said cutter means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means having high pressure areas subject to the fluid under pressure in the borehole annulus to effect expansion of said cutter means, and said releasable lock means including a chamber defined by said mandrel and a said body, one of said mandrel and said body having a port leading to said chamber, and valve means for closing said port to confine a quantity of hydraulic fluid in said chamber to prevent movement of said mandrel relative to said body when said port is closed.

Claim 13

In a rotary drill bit as defined in claim 7; said expanding means for said cutter means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means having high pressure areas subject to the fluid under pressure in the borehole annulus to effect expansion of said cutter means, said mandrel having a passage through which fluid pumped down the borehole annulus can flow upwardly and into the drill sTring, and said releasable lock means including a chamber defined by said mandrel and said body, one of said mandrel and said body having a port leading to said chamber, and valve means for closing said port to confine a quantity of hydraulic fluid in said chamber to prevent movement of said mandrel relative to said body when said port is closed.

Claim 14

In a rotary drill bit as defined in claim 7; said expanding means for said cutter means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means having high pressure areas subject to the fluid under pressure in the borehole annulus to effect expansion of said cutter means, said mandrel having a passage through which fluid pumped down the borehole annulus can flow upwardly and into the drill string, and said releasable lock means including a chamber defined by said mandrel and said body, one of said mandrel and said body having a port leading to said chamber, valve means for closing said port to confine a quantity of hydraulic fluid in said chamber to prevent movement of said mandrel relative to said body when said port is closed, and said valve means including a sleeve shiftably disposed in said passage and having means cooperable with a plug in a fluid stream flowing downwardly in said drill string for said port.

Claim 15

In a rotary drill bit as defined in claim 7; said expanding means for said cutter means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means having high pressure areas subject to the fluid under pressure in the borehole annulus to effect expansion of said cutter means, said mandrel having a passage through which fluid pumped down the borehole annulus can flow upwardly and into the drill string, said releasable lock means including a chamber defined by said mandrel and said body, one of said mandrel and said body having a port leading to said chamber, valve means for closing said port to confine a quantity of hydraulic fluid in said chamber to prevent movement of said mandrel relative to said body when said port is closed, said valve means including a sleeve shiftably disposed in said passage and having means cooperable with a plug in a fluid stream flowing downwardly in said drill string for opening said port, and means for reducing the pressure of the fluid flowing upwardly through the mandrel passage.

Claim 16

In a rotary drill bit as defined in claim 7; said expanding means for said cutter means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means having high pressure areas subject to the fluid under pressure in the borehole annulus to effect expansion of said cutter means, said mandrel having a passage through which fluid pumped down the borehole annulus can flow upwardly and into the drill string, said releasable lock means including a chamber defined by said mandrel and said body, said mandrel having a port leading to said chamber from said mandrel passage, valve means for closing said port to confine a quantity of hydraulic fluid in said chamber to prevent movement of said mandrel relative to said body when said port is closed, said valve means including a sleeve shiftably disposed in said mandrel passage and having means cooperable with a plug in a fluid stream flowing downwardly in said drill string for opening said port, means for reducing the pressure of the fluid flowing upwardly through the mandrel passage including an orifice leading into said mandrel passage, and means providing a normally closed opening larger than said orifice opening into said mandrel passage from the borehole and opened in response to longitudinal movement of said mandrel relative to said body in effecting expansion of said cutter means.

Claim 17

In a rotary drill bit as defined in claim 7; said expanding means for said cutter means comprising a mandrel movable longitudinally withIn and relative to said body, said body and mandrel providing cylinder and piston means having high pressure areas subject to the fluid under pressure in the borehole annulus to effect expansion of said cutter means, said mandrel having a passage through which fluid pumped down the borehole annulus can flow upwardly and into the drill string, said mandrel having flow restricting means in its passage for reducing the pressure of the fluid flowing upwardly through the mandrel passage, and means for communicating the low pressure areas of said cylinder and piston means with the reduced pressure region of said mandrel passage including a chamber defined between said mandrel and said body, a port leading between said mandrel passage and said chamber, and valve means movable between a first position closing said port and a second position opening said port.

Claim 18

In a rotary drill bit as defined in claim 7; said expanding means for said cutter means comprising a mandrel movable longitudinally within and relative to said body, said body and mandrel providing cylinder and piston means having high pressure areas subject to the fluid under pressure in the borehole annulus to effect expansion of said cutter means, said mandrel having a passage through which fluid pumped down the borehole annulus can flow upwardly and into the drill string, said mandrel having flow restricting means in its passage for reducing the pressure of the fluid flowing upwardly through the mandrel passage, means for communicating the low pressure areas of said cylinder and piston means with the reduced pressure region of said mandrel passage including a chamber defined between said mandrel and said body, a port leading between said mandrel passage and said chamber, valve means movable between a first position closing said port and a second position opening said port, and means for providing a normally closed opening leading into said mandrel from the borehole which is opened in response to longitudinal movement of said mandrel in said body in effecting expansion of said cutter means, said enlarged opening having a flow area at least equal to the flow area of a said mandrel passage.

Claim 19

In a rotary drill bit adapted for attachment to a drill string to be rotated thereby in a borehole: a main body, laterally expansible cutter means carried by said body, means including an inner mandrel engageable with said cutter means and responsive to the pressure of fluid in the region of the borehole externally of the drill bit for expanding said cutter means laterally outwardly of said body, said mandrel having a passage therethrough for the flow of fluid from said region of the borehole upwardly into said drill string, said mandrel having means providing a circulation flow path leading from said region into said mandrel passage, said mandrel having a flow restriction therein leading between said mandrel passage and the borehole and smaller than said circulation flow path for reducing the pressure of fluid in said mandrel passage, said flow path including a portion by passing said flow restriction, means closing said portion to enable said restriction to effect pressure reduction in said mandrel passage, and said body having a surface exposed to the reduced pressure in said mandrel passage, whereby said cutter means are expanded by differential pressure externally of and acting on said body.

Claim 20

In a rotary drill bit adapted for attachment to a drill string to be rotated thereby in a borehole: a main body, laterally expansible cutter means carried by said body, means including an inner mandrel engageable with said cutter means and responsive to the pressure of fluid in the region of the borehole externally of the drill bit for expanding said cutter means laterally outwardly of said body, said mandrel having a passage therethrough for the flow of fluid from said region of the borehole upwardly into said drill string, said mandrel having means providing a circulation flow path leading from said region into said mandrel passage, said mandrel having a flow restriction therein leading between said mandrel passage and the borehole and smaller than said circulation flow path for reducing the pressure of fluid in said mandrel passage, said flow path including a portion by passing said flow restriction, means closing said portion to enable said restriction to effect pressure reduction in said mandrel passage, and said body having a surface exposed to the reduced pressure in said mandrel passage, whereby said cutter means are expanded by differential pressure externally of and acting on said body.

Claim 21

In a rotary drill bit adapted for attachment to a drill string to be rotated thereby in a borehole: a main body, laterally expansible cutter means carried by said body, means including an inner mandrel engageable with said cutter means and responsive to the pressure of fluid in the region of the borehole externally of the drill bit for expanding said cutter means laterally outwardly of said body, said mandrel having a passage therethrough for the flow of fluid from said region of the borehole upwardly into said drill string, said mandrel having means providing a circulation flow path leading from said region into said mandrel pAssage and comprising an end portion on said mandrel, said end portion having a lateral port therein defining said circulation flow path and communicating with said mandrel passage, said end portion also having valve means for closing said mandrel passage when said circulation flow path is closed, and means closing said port until said cutter means are expanded, said port being open to provide a bypass around said valve when said cutter means are expanded.

Claim 22

In a rotary drill bit adapted for attachment to a drill string to be rotated thereby in a borehole: a main body, laterally expansible cutter means carried by said body, means including an inner mandrel engageable with said cutter means and responsive to the pressure of fluid in the region of the borehole externally of the drill bit for expanding said cutter means laterally outwardly of said body, said mandrel having a passage therethrough for the flow of fluid from said region of the borehole upwardly into said drill string, said mandrel having means providing a circulation flow path leading from said region into said mandrel pAssage and comprising an end portion on said mandrel, said end portion having a lateral port therein defining said circulation flow path and communicating with said mandrel passage, said end portion also having valve means for closing said mandrel passage when said circulation flow path is closed, and means closing said port until said cutter means are expanded, said port being open to provide a bypass around said valve when said cutter means are expanded.

Claim 23

In a rotary drill bit as defined in claim 17; said valve means including a downwardly facing seat circumscribing said mandrel passage, and a ball valve engageable with said seat to prevent entry of fluid from the borehole into said mandrel passage through said end portion when said circulation flow path is closed.

Claim 24

In a rotary drill bit as defined in claim 17; said valve means including a downwardly facing seat circumscribing said mandrel passage, and a ball valve engageable with said seat to prevent entry of fluid from the borehole into said mandrel passage through said end portion when said circulation flow path is closed, and said mandrel having a restricted opening leading into said mandrel passage above said end portion for enabling restricted entry of fluid from said borehole into said mandrel passage when said circulation flow path is closed.