Tool method and system for flushing a vertical riser

Abstract

A system for cleaning of vertical risers at floating drilling rigs, which comprises the following main components: a high-pressure pump ( 16 ); an umbilical hose ( 26 ) comprised of a hydraulic tubing and an electric cable, a cable winch unit ( 18 ) and an internal flushing device ( 20 ). The flushing device comprises a number of spring loaded centring wheels ( 32 ) around the body ( 31 ), one or more rotary high-pressure jets ( 34 ) in the body ( 31 ), collecting means ( 38 ) for larger particles at the lower section of the body ( 31 ) and a camera ( 40 ) fitted to the underside of the tool ( 30 ).

1 . Flushing device ( 20 ) for internal cleaning of a vertical riser ( 12 ) at a floating drilling rig ( 10 ), comprising a main body ( 31 ) detachable connected to a cable ( 28 ), characterised in that the flushing device ( 20 ) comprises a number of spring loaded centring wheels ( 32 ) around the body ( 31 ), one or more rotatable high-pressure jets ( 34 ) in the body ( 31 ), collecting means ( 38 ) at the lower section of the body ( 31 ) for larger particles, and a camera ( 40 ) arranged at the underside of the tool ( 20 ).  
     
     
         2 . Flushing device ( 20 ) in accordance with  claim 1 , characterised in that the spring loaded centring wheels ( 32 ) are arranged outwardly extending from the body ( 31 ) of the flushing device ( 20 ) towards the inner wall of the riser ( 12 ), and adapted to lie against this with a force which is sufficient to centre the tool in the riser, and in which the centring wheels ( 32 ) are preferably arranged radially around the body ( 31 ) in a number of wheel groups ( 32   a,    32   b ).  
     
     
         3 . Flushing device ( 20 ) in accordance with  claim 1 , characterised in that the high-pressure jet ( 34 ) is arranged rotatively in adapted apertures in the central axis of the body ( 31 ) and comprises a swivel with jets through which the cleaning fluid is led under high pressure.  
     
     
         4 . Flushing device ( 20 ) in accordance with  claim 1 , characterised in that the collecting means ( 38 ) is arranged in or at the lower section of the body ( 31 ) and has an outer circular-cylindrical shape with its size being somewhat less than the inner diameter of the riser to allow passage of fluid between them and with an inner opening adapted to the collection of particles which are released from the inner wall of the riser ( 12 ) by the flushing device.  
     
     
         5 . Method for internal cleaning of vertical riser ( 12 ), where the sludge pumps of the drilling rig ( 10 ) circulate fluid through the riser ( 12 ), characterised in 
 that a flushing device ( 20 ), according to claims  1 - 4 , is led into the riser ( 12 ) and thereafter led all the way down to a blow-out preventer (BOP) at the well head,    that a high-pressure unit ( 16 ) supplies fluid down to the flushing device ( 20 ) by way of an umbilical hose ( 26 ) which is led down in the riser ( 12 ) with the aid of a hydraulic winch ( 18 ),    that at the same time as high pressure is supplied to the flushing device ( 20 ) the sludge pump of the drilling rig ( 10 ) starts to deliver a fluid stream in the riser ( 12 ) to flush out particles which are released from the wall of the riser by the flushing device ( 20 ),    that the flushing device ( 20 ) is pulled upwards in the riser ( 12 ) until it reaches the top of the riser.    
     
     
         6 . Method in accordance with  claim 5 , characterised in that particles larger than the fluid stream can lift are caught by a trap or a collecting means ( 38 ) in or at the flushing device ( 20 ).  
     
     
         7 . System for cleaning of a vertical riser at a floating drilling rig, comprising a high-pressure pump ( 16 ), an umbilical hose ( 26 ) comprising a hydraulic tubing and an electric cable, and a cable winch unit ( 18 ), characterised in that the system further comprises an internal flushing device ( 20 ) according to claims  1 - 4 .  
     
     
         8 . System in accordance with  claim 7 , characterised in that the high-pressure pump ( 16 ) functions as a pressure generator to provide an ultra high pressure from 700 to 1100 bar, preferably 830-950 bar, and for feeding of fluid to an internal flushing device ( 20 ) at a fluid flow from 5 m 3 /h to 20 m 3 /h, preferably from 10 m 3 /h to 15 m 3 /h, even more preferred from about 12 m 3 /h to 14 m 3 /h.  
     
     
         9 . System in accordance with  claim 7 , characterised in that the winch unit ( 18 ) is hydraulically driven and that the high-pressure hose and the electric cable are constructed as one body, furthermore the winch unit ( 18 ) comprises equipment for reading of a load cell at the end of the cable and digital metre counter to read the height level in the riser.