Method of supplying cement slurry and method of drilling or cementing of well using the same

Abstract

Cement slurry is prevented from coming into contact with hardening accelerator in a cementing tool in a simple manner. The method of supplying cement slurry has the steps of: adding capsule C to cement slurry, wherein capsule C is filled with hardening accelerator for the cement slurry; and supplying the cement slurry to a hole, wherein capsule C is added to the cement slurry, and the cement slurry is supplied through cementing tool 105 that is provided in the hole. Capsule C melts or collapses after a specific amount of time passes, wherein the specific amount of time is longer than a flow out time, which is a time for capsule C to flow out of cementing tool 105 after capsule C is added to the cement slurry.

1 . A method of supplying cement slurry comprising the steps of:
 adding a capsule to cement slurry, wherein the capsule is filled with hardening accelerator for the cement slurry; and   supplying the cement slurry to a hole, wherein the capsule is added to the cement slurry, and the cement slurry is supplied through a cementing tool that is provided in the hole, wherein the capsule melts or collapses after a specific amount of time passes, wherein the specific amount of time is longer than a flow out time, which is a time for the capsule to flow out of the cementing tool after the capsule is added to the cement slurry.   
     
     
         2 . The method of supplying cement slurry according to  claim 1 , wherein the capsule is added to the cement slurry downstream of a slurry pump that pumps the cement slurry into the hole. 
     
     
         3 . The method of supplying cement slurry according to  claim 1 , wherein the capsule is added to the cement slurry upstream of a slurry pump that pumps the cement slurry into the hole. 
     
     
         4 . The method of supplying cement slurry according to  claim 1 , wherein the hardening accelerator is calcium chloride, silicate of soda or mixture thereof 
     
     
         5 . The method of supplying cement slurry according to  claim 1 , wherein the capsule has melting characteristics that depend on at least one selected from among pressure, temperature and pH. 
     
     
         6 . A method of drilling a hole comprising the steps of:
 drilling a hole using a bit that is provided at an end of a drill while supplying drilling mud to the hole through an inner fluid passage of the drill and recovering the drilling mud from an annulus between a wall of the hole and the drill;   stopping the drilling using the drill when occurrence of lost circulation from the wall of the hole is detected based on a flow rate of the drilling mud that is supplied and a flow rate of the drilling mud that is recovered; and   supplying cement slurry to the hole after the drilling is stopped, wherein a capsule is added to the cement slurry by the method of supplying cement slurry according to  claim 1 .   
     
     
         7 . The method of drilling a hole according to  claim 6 , wherein an injection port for the cement slurry of the cementing tool is provided near a bottom of the hole, the bottom existing when the drilling is stopped, and the flow rate of the cement slurry that is supplied is adjusted depending on depth of the injection port such that the capsule melts or collapses after the capsule flows out of the injection port. 
     
     
         8 . The method of drilling a hole according to  claim 7 , wherein the specific amount of time is adjusted such that the capsule melts or collapses near a location where the lost circulation occurs. 
     
     
         9 . The method of drilling a hole according to  claim 6 , wherein the drill is raised out of the hole after the drilling is stopped, and the drill is provided in the hole again as the cementing tool after the bit is detached. 
     
     
         10 . The method of drilling a hole according to  claim 6 , wherein the capsule that is filled with the hardening accelerator has about a same specific weight as the cement slurry. 
     
     
         11 . A method of cementing comprising the steps of:
 supplying cement slurry to a hole through a cementing tool that is provided in a hollow cylindrical body in the hole, wherein the cement slurry is supplied by the method of supplying cement slurry according to  claim 1 , wherein   the cement slurry turns around a lower end of the hollow cylindrical body into an annulus between the hollow cylindrical body and a wall of the hole, flows upward through the annulus to fill the annulus, thereby the hollow cylindrical body is fixed to the wall of the hole.   
     
     
         12 . A method of cementing comprising the steps of:
 supplying cement slurry to a hole through a cementing tool that is provided in the hole, wherein the cement slurry is supplied by the method of supplying cement slurry according to  claim 1 , wherein,   a cement plug is formed at a bottom of the hole by the cement slurry.   
     
     
         13 . The method of cementing according to  claim 12 , wherein the capsule that is filled with the hardening accelerator has a larger specific weight than the cement slurry. 
     
     
         14 . A method of cementing comprising the steps of:
 supplying cement slurry to a hole through a cementing tool that is provided in a hollow cylindrical body in the hole, wherein the cement slurry is supplied by the method of supplying cement slurry according to  claim 1 , wherein   a defect of cement between the hollow cylindrical body and a wall of the hole communicates with interior of the hollow cylindrical body via a hole that is open on a wall of the hollow cylindrical body, and the cement slurry is supplied to a predetermined depth region that includes the hole of the hollow cylindrical body, and the cement slurry fill the defect via the hole.   
     
     
         15 . A capsule that is filled with hardening accelerator for cement slurry, wherein
 the capsule is added to the cement slurry, and the cement to which the capsule is added, is supplied to a hole through a cementing tool that is provided in the hole, and   the capsule melts or collapses after a specific amount of time passes, wherein the specific amount a time is longer than a flow out time, which is a time for the capsule to flow out of the cementing tool after the capsule is added to the cement slurry.   
     
     
         16 . The capsule according to  claim 15 , wherein the hardening accelerator is calcium chloride, silicate of soda or mixture thereof. 
     
     
         17 . The capsule according to  claim 15 , wherein the capsule has melting characteristics that depend on at least one selected from among pressure, temperature and pH. 
     
     
         18 . The capsule according to  claim 15 , wherein the capsule that is filled with the hardening accelerator has about a same specific weight as the cement slurry. 
     
     
         19 . The capsule according to  claim 15 , wherein the capsule that is filled with the hardening accelerator has a larger specific weight than the cement slurry.