Subsea Flowline Blockage Remediation Using Internal Heating Device

Abstract

Coiled tubing may be placed inside a subsea flowline, such as with a subsea insertion tool, to remediate blockages in the flowline subsea. In embodiments, the subsea insertion tool is used to unspool a length of coiled tubing string from a coiled tubing reel and insert the unspooled coiled tubing string subsea into flowline to where a jetting nozzle is positioned proximate a blockage in flowline 120. Fluid is provided, e.g. pumped, from chemical pumping unit 80 to coiled tubing string 100 through to jetting nozzle 110 to remediate the blockage in flowline 120.

1 . A subsea insertion tool, comprising:
 a. a coiled tubing inserter adapted to insert a coiled tubing string into, and remove the coiled tubing string out from, a flowline subsea;   b. a sealer configured to form a dynamic seal on an outer diameter of the coiled tubing string;   c. a gate valve adapted to aid in primary sealing of flowline line fluids from the environment;   d. a disconnect valve adapted to aid in emergency disconnection of the coiled tubing string;   e. a large bore connector adapted to aid in venting and/or flushing the flowline during operation to de-pressurize and de-inventory the flowline; and   f. a flowline connector adapted to connect with a pipeline termination.   
     
     
         2 . The subsea insertion tool of  claim 1  wherein the subsea coiled tubing inserter comprises a coiled tubing injector head. 
     
     
         3 . The subsea insertion tool of  claim 1  wherein the sealer comprises a stripper packer. 
     
     
         4 . The subsea insertion tool of  claim 1  wherein the disconnect valve further comprises a blowout preventor valve. 
     
     
         5 . The subsea insertion tool of  claim 1  wherein the disconnect valve further comprises a shear ram or a grip/seal ram. 
     
     
         6 . The subsea insertion tool of  claim 1 , further comprising a coiled tubing cutter adapted to cut coiled tubing and/or the coiled tubing string in case of emergency disconnect, the coiled tubing cutter located externally to the coiled tubing inserter. 
     
     
         7 . The subsea insertion tool of  claim 1 , further comprising a flexible flowline disposed between the subsea insertion tool and the flowline termination and adapted to aid with horizontal insertion to aid in alignment. 
     
     
         8 . The subsea insertion tool of  claim 1 , further comprising an alignment system for aligning the tool with a pipeline termination. 
     
     
         9 . The subsea insertion tool of  claim 1 , further comprising:
 a. a first remotely operated vehicle (ROV) panel disposed proximate a first end of the subsea insertion tool and operatively in communication with the coiled tubing inserter; and   b. a second remotely operated vehicle (ROV) panel disposed proximate a second end of the subsea insertion tool and operatively in communication with the gate valve and the disconnect valve.   
     
     
         10 . A coiled tubing string assembly, comprising:
 a. a coiled tubing control unit located on a topside vessel, the coiled tubing control unit comprising a coiled tubing reel;   b. a coiled tubing string comprising a predetermined length of coiled tubing disposed about the coiled tubing reel;   c. a heater disposed inside the coiled tubing;   d. a jetting nozzle disposed at a predetermined end of the coiled tubing string; and   e. a vibrator at the end of the coiled tubing string, the vibrator adapted to provide vibration to aid in horizontal movement within a flowline.   
     
     
         11 . The coiled tubing string assembly of  claim 10 , wherein the heater comprises a heating cable. 
     
     
         12 . The coiled tubing string assembly of  claim 11 , wherein the heating cable comprises a mineral insulated cable. 
     
     
         13 . The coiled tubing string assembly of  claim 10 , wherein the vibrator comprises an agitator, a vibrator, or an impact hammer. 
     
     
         14 . A heated coiled tubing string system, comprising a coiled tubing string assembly, the coiled tubing string assembly comprising:
 a. a coiled tubing control unit comprising a coiled tubing reel;   b. a coiled tubing string comprising a predetermined length of coiled tubing disposed about the coiled tubing reel;   c. a heater disposed inside the coiled tubing; and   d. a jetting nozzle disposed at a predetermined end of the coiled tubing string.   
     
     
         15 . A method of using coiled tubing inside a subsea flowline to remediate blockages in a subsea flowline using a heated coiled tubing string system which comprises a coiled tubing string assembly, the coiled tubing string assembly comprising a coiled tubing control unit comprising a coiled tubing reel; a coiled tubing string comprising a predetermined length of coiled tubing disposed about the coiled tubing reel; a heater disposed inside the coiled tubing; and a jetting nozzle disposed at a predetermined end of the coiled tubing string, the heated coiled tubing string system further comprising a chemical pumping unit in fluid communication with the coiled tubing string, the method comprising:
 a. unspooling the coiled tubing string from the coiled tubing reel;   b. inserting the unspooled coiled tubing string subsea into a flowline subsea until the jetting nozzle is positioned proximate a blockage;   c. providing fluid from the chemical pumping unit to the coiled tubing string through to the jetting nozzle; and   d. using the jetting nozzle to remediate the blockage in the subsea flowline.   
     
     
         16 . The method of  claim 15 , wherein the coiled tubing string is inserted subsea into the subsea flowline from a pipeline termination. 
     
     
         17 . The method of  claim 15 , wherein the coiled tubing string is inserted subsea into the subsea flowline from a platform at a riser. 
     
     
         18 . The method of  claim 15 , further comprising energizing the heater to heat fluid within the coiled tubing string to a temperature appropriate the achieve the remediation of the blockage. 
     
     
         19 . The method of  claim 15 , wherein the coiled tubing string is inserted subsea into the subsea flowline using a subsea insertion tool deployed subsea, the subsea insertion tool comprising a coiled tubing inserter adapted to insert and remove the coiled tubing string into the flowline subsea; a sealer configured to form a dynamic seal on an outer diameter of the coiled tubing string; a gate valve adapted to aid in primary sealing of flowline line fluids from the environment; a disconnect valve adapted to aid in emergency disconnection of the coiled tubing string; a large bore connector adapted to aid in venting and/or flushing the flowline during operation to de-pressurize and de-inventory the flowline; and a flowline connector adapted to connect with a pipeline termination. 
     
     
         20 . The method of  claim 19 , wherein the gate valve is used when the coiled tubing is not in a bore of the valve.