Downhole Circulation Apparatus

Abstract

A downhole circulation apparatus comprises at least one tubular body portion defining a first through-flow passage through which drilling fluid can pass along the drill string. A first sleeve is slidably mounted in the tubular body portion and is biased into a position in which the first port means is closed by a biasing means such as a spring. Second port means is formed through the tubular body portion at a location below the first port means in the drill string. The second port means may comprise a plurality of second nozzles, wherein each of the second nozzles has a diameter greater than the diameter of each of the first nozzles of the first port means. Larger nozzles enable large particle size drilling fluid to be bypassed. A second sleeve is slidably mounted inside the tubular body portion.

1 . A downhole circulation apparatus arranged to be mounted in a drill string, the apparatus comprising:
 at least one tubular body portion for mounting in a drill string, at least one said tubular body portion defining a first through-flow passage for receiving a flow of drilling fluid through the drill string;   first port means formed through at least one said tubular body portion;   a first sleeve slidably mounted inside at least one said tubular body portion, the first sleeve moveable between a closed position in which said first port means is closed by the first sleeve and an open position in which said first port means is open to allow drilling fluid in to circulate out of the apparatus;   first biasing means biasing the first sleeve into the closed position;   second port means formed through at least one said tubular body portion at a location below the first port means when the apparatus is in use;   a second sleeve slidably mounted inside at least one said tubular body portion, the second sleeve moveable between a closed position in which said second port means is closed by the second sleeve and an open position in which said second port means is open to allow drilling fluid to circulate out of the apparatus; and   second biasing means biasing the second sleeve into the closed position.   
     
     
         2 . An apparatus according to  claim 1 , wherein at least one of the first sleeve and the second sleeve comprises a flow responsive portion responsive to a flow or a pressure of drilling fluid through the first through-flow passage to be thereby movable between the closed position and the open position depending on the flow of drilling fluid. 
     
     
         3 . An apparatus according to  claim 2 , comprising a first clutch member secured to the at least one said tubular body portion and a second clutch member axially spaced from the first clutch member and secured to the at least one said tubular body portion, the respective sleeve being axially arranged between the first clutch member and the second clutch member and being movable between cooperative engagement with the first clutch member or the second clutch member, the cooperative engagement being controlled by an indexable latch mechanism. 
     
     
         4 . An apparatus according to  claim 1 ,
 wherein at least one of the first sleeve and the second sleeve comprises engagement means configured for receiving a first restriction device;   wherein the apparatus comprises the first restriction device comprising a second through-flow passage and configured so that dropping the first restriction device into the apparatus causes the first restriction device to engage the engagement means to cause an increase in fluid pressure in the apparatus above the first restriction device which moves the respective sleeve from the closed to the open position;   wherein the apparatus comprises a second restriction device configured so that dropping the second restriction device into the apparatus causes the second restriction device to engage the first restriction device and block the second through-flow passage to cause a fluid pressure increase in the apparatus above the first and second restriction devices which moves the first and second restriction devices past the respective sleeve to cause the respective biasing means to move the respective sleeve back to the closed position.   
     
     
         5 . An apparatus according to  claim 4 ,
 wherein the apparatus comprises deactivation means configured so that dropping the deactivation means into the apparatus closes the respective port means to cause a further fluid pressure increase in the apparatus above the first and second restriction devices which moves the first and second restriction devices and the deactivation means past the respective sleeve to cause the respective biasing means to move the respective sleeve back to the closed position.   
     
     
         6 . An apparatus according to  claim 4 , wherein the second restriction device and/or the deactivation means is connected to a wireline. 
     
     
         7 . An apparatus according to  claim 1 ,
 wherein at least one of the first sleeve and the second sleeve comprises engagement means configured for receiving activation means;   wherein the apparatus comprises the activation means configured so that dropping the activation means into the apparatus causes the activation means to engage the engagement means to cause an increase in fluid pressure in the apparatus above the activation means which moves the respective sleeve from the closed to the open position;   wherein the apparatus comprises deactivation means configured so that dropping the deactivation means into the apparatus closes the respective port means to cause a further fluid pressure increase in the apparatus above the activation means which moves the activation means and the deactivation means past the respective sleeve to cause the respective biasing means to move the respective sleeve back to the closed position.   
     
     
         8 . An apparatus according to  claim 7 ,
 wherein the apparatus comprises locking means configured so that dropping the locking means into the apparatus locks the respective port means open until the deactivation means force the locking means to move out of the port means towards an exterior of the tubular body portion.   
     
     
         9 . An apparatus according to  claim 1 ,
 wherein at least one of the first sleeve and the second sleeve comprises engagement means configured for receiving frangible activation means;   wherein the apparatus comprises the frangible activation means configured so that dropping the frangible activation means into the apparatus causes the frangible activation means to engage the engagement means to cause an increase in fluid pressure in the apparatus above the frangible activation means which moves the respective sleeve from the closed to the open position;   wherein the frangible activation means is configured so that a further fluid pressure increase in the apparatus above the frangible activation means breaks the frangible activation means which thereby moves through the engagement means to cause a decrease in fluid pressure in the apparatus above the engagement means which moves the respective sleeve from the closed to the open position.   
     
     
         10 . An apparatus according to  claim 1 ,
 wherein one of the first sleeve and the second sleeve is configured according to  claim 2 , and the other one of the first sleeve and the second sleeve is configured according to  claim 7 ;   wherein the flow responsive portion is dimensioned to be passable by the activation means.   
     
     
         11 . An apparatus according to  claim 1 ,
 wherein one of the first sleeve and the second sleeve is configured according to  claim 2 , and the other one of the first sleeve and the second sleeve is configured according to  claim 4 ;   wherein the flow responsive portion is dimensioned to be passable by the first restriction device.   
     
     
         12 . An apparatus according to  claim 1 ,
 wherein the first sleeve and the second sleeve are both configured according to  claim 7 ;   wherein one or more ports of the first port means have a smaller dimension than one or more ports of the second port means;   wherein the deactivation means for the first sleeve is dimensioned to pass through the second port means.   
     
     
         13 . An apparatus according to  claim 1 ,
 wherein the first sleeve and the second sleeve are both configured according to  claim 9 ;   wherein the frangible activation means for the second sleeve is dimensioned to pass through the engagement means of the first sleeve.   
     
     
         14 . An apparatus according to  claim 1 ,
 wherein the first sleeve and the second sleeve are both configured according to  claim 4 ;   wherein the first restriction device for the first sleeve is the first restriction device for the second sleeve.   
     
     
         15 . An apparatus according to  claim 1 , wherein the apparatus comprises at least one restriction device configured so that
 dropping the at least one restriction device into the apparatus causes the at least one restriction device to engage first engagement means of the first sleeve to cause an increase in fluid pressure in the apparatus above the at least one restriction device which moves the first sleeve from the closed to the open position; and   releasing the at least one restriction device from the first engagement means of the first sleeve moves the at least one restriction device down the apparatus to engage second engagement means of the second sleeve to cause a fluid pressure increase in the apparatus above the at least one restriction device to move the second sleeve from the closed to the open position.   
     
     
         16 . An apparatus according to  claim 1 , wherein the apparatus comprises:
 third port means formed through at least one said tubular body portion at a location below the second port means when the apparatus is in use;   a third sleeve slidably mounted inside at least one said tubular body portion, the third sleeve moveable between a closed position in which said third port means is closed by the third sleeve and an open position in which said third port means is open to allow drilling fluid to circulate out of the apparatus; and   third biasing means biasing the third sleeve into the closed position.   
     
     
         17 . An apparatus according to  claim 1 , wherein the apparatus is arranged such that:
 a) dropping a first restriction device comprising a second through-flow passage into the apparatus causes the first restriction device to engage first engagement means of said first sleeve to cause an increase in fluid pressure in the apparatus above the first restriction device which moves the first sleeve from the closed to the open position;   b) dropping a second restriction device into the apparatus after the first restriction device has been dropped causes the second restriction device to engage the first restriction device and block the second through-flow passage to cause a fluid pressure increase in the apparatus above the first and second restriction devices which moves the first and second restriction devices past the first sleeve to cause the first biasing means to move the first sleeve back to the closed position; and   c) wherein the first and second restriction devices move down the apparatus to engage second engagement means of said second sleeve to cause a fluid pressure increase in the apparatus above the first and second restriction devices to move the second sleeve from the closed to the open position.   
     
     
         18 . An apparatus according to  claim 17 , wherein the second sleeve is moveable back to the closed position by said second biasing means in response to dropping deactivation means into the apparatus to block said second port means and cause a fluid pressure increase in the apparatus to move the first and second restriction devices past the second sleeve. 
     
     
         19 . An apparatus according to  claim 18 , wherein the deactivation means comprises at least one deactivation ball. 
     
     
         20 . An apparatus according to  claim 1 , further comprising a restriction device catcher located below said second sleeve when the apparatus is in use. 
     
     
         21 . An apparatus according to  claim 1 , wherein said first port means comprises a plurality of first nozzles arranged to direct drilling fluid into a drilled borehole in a direction opposite to the direction of advancement of the apparatus. 
     
     
         22 . An apparatus according to  claim 21 , wherein said plurality of first nozzles is formed from tungsten carbide. 
     
     
         23 . An apparatus according to  claim 6 , wherein the second port means comprises a plurality of second nozzles, wherein each said second nozzle has a diameter greater than the diameter of each of said first nozzles. 
     
     
         24 . An apparatus according to  claim 17 , wherein the first restriction device is arranged to allow approximately 70% of the fluid flow in the apparatus to pass through the second through-flow passage when engaged with the first engagement means, such that approximately 30% of the fluid flow in the apparatus is directed through said first port means. 
     
     
         25 . An apparatus according to  claim 1 , wherein the apparatus is formed from an assembly of a plurality of drill string elements comprising:
 a first tool element comprising a first tubular body portion, first port means formed through said first tubular body portion and a first sleeve slidably mounted inside said first tubular body portion;   a second tool element arranged below said first tool element when the apparatus is in use, the second tool element comprising a second tubular body portion, second port means formed through said second tubular body portion and a second sleeve slidably mounted inside said second tubular body portion; and   at least one drill pipe element disposed between and interconnecting said first tool element with said second tool element.   
     
     
         26 . An apparatus according to  claim 25 , further comprising a plurality of drill pipe elements disposed between and interconnecting said first tool element with said second tool element. 
     
     
         27 . An apparatus according to  claim 17 , wherein said first restriction device is a dart comprising:
 a hollow body portion defining said second through-flow passage;   at least one deformable portion arranged to engage the first and second engagement means of the respective first and second sleeves; and   a ball seat disposed in the second through-flow passage, the ball seat arranged to receive a ball to block said second through-flow passage.   
     
     
         28 . An apparatus according to  claim 27 , wherein said dart further comprises retention means disposed adjacent said ball seat, the retention means arranged to prevent a ball located in the ball seat from moving out of the ball seat in a first direction, but permit a ball located in the ball seat to move past the ball seat in a second direction. 
     
     
         29 . An apparatus according to  claim 28 , wherein said retention means comprises a plurality of teeth disposed on the hollow body portion. 
     
     
         30 . An apparatus according to  claim 17 , wherein said second restriction device comprises a ball. 
     
     
         31 . (canceled) 
     
     
         32 . A downhole circulation system arranged such that
 a) dropping a first restriction device comprising a second through-flow passage into the apparatus causes the first restriction device to engage first engagement means of said first sleeve to cause an increase in fluid pressure in the apparatus above the first restriction device which moves the first sleeve from the closed to the open position,   b) dropping a second restriction device into the apparatus after the first restriction device has been dropped causes the second restriction device to engage the first restriction device and block the second through-flow passage to cause a fluid pressure increase in the apparatus above the first and second restriction devices which moves the first and second restriction devices past the first sleeve to cause the first biasing means to move the first sleeve back to the closed position, and   c) wherein the first and second restriction devices move down the apparatus to engage second engagement means of said second sleeve to cause a fluid pressure increase in the apparatus above the first and second restriction devices to move the second sleeve from the closed to the open position, the downhole circulation system, comprising:   a first restriction device comprising a second through-flow passage; and   a second restriction device adapted to engage said first restriction device and block the second through-flow passage.   
     
     
         33 . (canceled) 
     
     
         34 . A method of operating a downhole circulation apparatus having at least one tubular body portion for mounting in a drill string, the at least one said tubular body portion defining a first through-flow passage for receiving a flow of drilling fluid through the drill string, first port means formed through at least one said tubular body portion, a first sleeve slidably mounted inside at least one said tubular body portion, the first sleeve moveable between a closed position in which said first port means is closed by the first sleeve and an open position in which said first port means is open to allow drilling fluid to circulate out of the apparatus, first biasing means biasing the first sleeve into the closed position, second port means formed through at least one said tubular body portion at a location below the first port means when the apparatus is in use, a second sleeve slidably mounted inside at least one said tubular body portion, the second sleeve moveable between a closed position in which said second port means is closed by the second sleeve and an open position in which said second port means is open to allow drilling fluid to circulate out of the apparatus and second biasing means biasing the second sleeve into the closed position, the method comprising:
 a) causing an increase in fluid pressure in the apparatus to move the first sleeve from the closed to the open position;   b) causing the first biasing means to move the first sleeve back to the closed position; and   c) causing a fluid pressure increase in the apparatus to move the second sleeve from the closed to the open position.   
     
     
         35 . A method of  claim 34 , the method comprising:
 a) dropping a first restriction device comprising a second through-flow passage into the apparatus to cause the first restriction device to engage first engagement means of said first sleeve and cause an increase in fluid pressure in the apparatus above the first restriction device to move the first sleeve from the closed to the open position;   b) dropping a second restriction device into the apparatus after the first restriction device has been dropped to cause the second restriction device to engage the first restriction device and block the second through-flow passage to cause a fluid pressure increase in the apparatus above the first and second restriction devices which moves the first and second restriction devices past the first sleeve and causes the first biasing means to move the first sleeve back to the closed position; and   c) wherein the first and second restriction devices move down the apparatus to engage second engagement means of said second sleeve to cause a fluid pressure increase in the apparatus above the first and second restriction devices to move the second sleeve from the closed to the open position.   
     
     
         36 . A method according to  claim 35 , further comprising:
 dropping at least one deactivation means into the apparatus to block said second port means and cause a fluid pressure increase in the apparatus to move the first and second restriction devices past the second sleeve and cause the second biasing means to move the second sleeve back to the closed position.   
     
     
         37 . (canceled)