Assembly and method for placing a cement plug

Abstract

An assembly for placing a cement plug ( 1 ) in a well-bore comprises a landing and disconnecting collar ( 2 ), a shoe track ( 3 ), a circulation element ( 4 ), and a guide shoe ( 5 ), said elements forming an internal conduit ( 10 ), the circulation element ( 4 ) comprising side conduits ( 8 ) directed towards a well-bore wall (WBW). The assembly ( 1 ) diameter is such as to create a narrow annulus (AN 2 ) in which a fluid pumped through the side conduits ( 8 ) circulates in the annulus according to a turbulent flow. The assembly ( 1 ) further comprises a sealing element ( 6 ) comprising a bottom sealing element ( 6 A). The landing and disconnecting collar ( 2 ), shoe track ( 3 ), circulation element ( 4 ), and guide shoe ( 5 ) are made of material that are drillable, the elements forming the cement plug when a cement slurry (CS) is set into the annulus (AN 2 ) and the internal conduit ( 10 ).

1 . An assembly for placing a cement plug in a well-bore comprising a landing and disconnecting collar, a shoe track, a circulation element, and a guide shoe, said elements forming an internal conduit, the circulation element comprising side conduits directed towards a well-bore wall,
 wherein the assembly diameter is such as to create a narrow annulus in which a fluid pumped through the side conduits circulates in the annulus according to a turbulent flow, wherein the assembly further comprises a sealing element comprising a bottom sealing element, and   wherein the landing and disconnecting collar, shoe track, circulation element, and guide shoe are made of material that are drillable, said elements forming the cement plug when a cement slurry is set into the annulus and the internal conduit.   
     
     
         2 . An assembly for placing a cement plug according to  claim 1 , wherein the assembly further comprises a top sealing element. 
     
     
         3 . An assembly for placing a cement plug according to  claim 1 , wherein the material is chosen among the group of material comprising Aluminum, fiberglass, cement, plastic, and carbon fiber reinforced material. 
     
     
         4 . An assembly for placing a cement plug according to  claim 1 , wherein the assembly further comprises a centralizer. 
     
     
         5 . An assembly for placing a cement plug according to  claim 1 , wherein the guide shoe further comprises a differential pressure valve for reducing any piston effect on a geological formation surrounding the well-bore. 
     
     
         6 . An assembly for placing a cement plug according to  claim 1 , wherein the sealing element is a flexible cup-like packer or an external casing packer. 
     
     
         7 . A method of placing a cement plug in a well-bore comprising:
 assembling a cement plug placing assembly and coupling said assembly to a drill pipe,   running the cement plug placing assembly to a desired depth,   cleaning the well-bore wall by circulating fluid in said assembly by producing a jetting effect towards the well-bore wall and a turbulent flow in a limited annulus portion defined between the cement plug placing assembly and the well-bore wall,   mixing and pumping a cement slurry into the drill pipe,   displacing the cement slurry towards the cement plug placing assembly and into the annulus portion, and   disconnecting the drill pipe after a pressure bump at the end of the displacing step.   
     
     
         8 . A method of placing a cement plug according to  claim 7 , wherein a length of the cement plug is defined by coupling casing joints during the assembling step. 
     
     
         9 . A method of placing a cement plug according to  claim 7 , wherein the drill pipe is rotated for sweeping a whole circumference of the well-bore wall during the cleaning step. 
     
     
         10 . The method of  claim 7 , wherein the cement plug placing assembly comprises a landing and disconnecting collar, a shoe track, a circulation element, and a guide shoe, wherein said elements form an internal conduit and the circulation element comprises side conduits directed towards a well-bore wall. 
     
     
         11 . The method of  claim 10 , wherein the cement plug placing assembly diameter is such as to create a narrow annulus in which a fluid pumped through the side conduits circulates in the annulus according to a turbulent flow. 
     
     
         12 . The method of  claim 10 , wherein the cement plug placing assembly further comprises a sealing element comprising a bottom sealing element. 
     
     
         13 . The method of  claim 10 , the landing and disconnecting collar, shoe track, circulation element, and guide shoe are made of material that are drillable, said elements forming the cement plug when a cement slurry is set into the annulus and the internal conduit. 
     
     
         14 . The method of  claim 7 , wherein the cement plug placing assembly further comprises a top sealing element. 
     
     
         15 . The method of  claim 13 , wherein the material is chosen among the group of material comprising Aluminum, fiberglass, cement, plastic, and carbon fiber reinforced material. 
     
     
         16 . The method of  claim 7 , wherein the cement plug placing assembly further comprises a centralizer. 
     
     
         17 . The method of  claim 10 , wherein the wherein the guide shoe further comprises a differential pressure valve for reducing any piston effect on a geological formation surrounding the well-bore. 
     
     
         18 . The method of  claim 12 , wherein the sealing element is a flexible cup-like packer or an external casing packer. 
     
     
         19 . A method for well-bore treatment, comprising:
 assembling a cement plug placing assembly and coupling said assembly to a drill pipe,   running the cement plug placing assembly to a desired depth,   cleaning the well-bore wall by circulating fluid in said assembly by producing a jetting effect towards the well-bore wall and a turbulent flow in a limited annulus portion defined between the cement plug placing assembly and the well-bore wall,   mixing and pumping a cement slurry into the drill pipe,   displacing the cement slurry towards the cement plug placing assembly and into the annulus portion, and   disconnecting the drill pipe after a pressure bump at the end of the displacing step.   
     
     
         20 . The method according to  claim 19 , wherein the treatment is one or more of primary cementing, remedial cementing, wellbore stabilization, lost circulation treatment, cement plug setting.