Method of processing and separating a multiphase well effluent mixture

Abstract

A method of processing a multiphase well effluent mixture comprises: transferring the mixture (L+G) via a multiphase well effluent flowline ( 2 ) to a gas liquid separator ( 1 ) in which the multiphase well effluent mixture is separated into substantially gaseous and liquid fractions; transferring the substantially liquid fraction (L) into a liquid flowline ( 6 ) in which liquid pump ( 7 ) is arranged; transferring the substantially gaseous fraction (G) into a gas flowline ( 8 ) in which a gas compressor ( 9 ) is arranged; protecting the gas compressor ( 9 ) against liquid and/or pressure surges due to low gas flow rate and/or backflow of compressed gas by recirculating a recycled gas stream (G hot ) via a gas recycling conduit ( 10 ) through the gas compressor in response to detection of the onset of a liquid surge in the multiphase well effluent mixture and/or of a pressure surge due to low gas flow rate and/or a high pressure differential across the gas compressor ( 9 ); and cooling the recycled gas stream by contacting recycled hot gas (G hot ) with relatively cold liquid L within the separator ( 1 ) or associated flowlines ( 2, 6 ) preferably using an array of gas injection nozzles ( 14 ) which inject the hot gas (G hot ) as finely dispersed gas bubbles into the liquid (L).

1 . A method of processing and separating a multiphase well effluent mixture, the method comprising:
 transferring the multiphase well effluent mixture via a multiphase well effluent flowline to a gas liquid separator in which the multiphase well effluent mixture is separated into substantially gaseous and liquid fractions;   transferring the substantially liquid fraction into a liquid flowline in which a liquid pump is arranged;   transferring the substantially gaseous fraction into a gas flowline in which a gas compressor is arranged;   protecting the gas compressor against pressure and/or liquid surges by recirculating a recycled gas stream via a gas recycling conduit through the gas compressor in response to detection of the onset of a pressure and/or liquid surge in the multiphase well effluent mixture and/or of a high pressure differential across the gas compressor; and   cooling the recycled gas stream by contacting recycled gas with liquid.   
   
   
       2 . The method of  claim 1 , wherein recycled gas is contacted with liquid by injecting recycled gas into a liquid filled section of the gas liquid separator. 
   
   
       3 . The method of  claim 2 , wherein the gas liquid separator is a gravity separation vessel and liquid filled section is located near the bottom of the vessel. 
   
   
       4 . The method of  claim 3 , wherein gas is injected into the liquid filled section by a series of gas injection nozzles, which inject the recycled gas as an array of finely dispersed gas bubbles into the liquid. 
   
   
       5 . The method of  claim 4 , wherein the series of gas injection nozzles is arranged in a ring shaped gas injection conduit, which is located at a selected distance above the bottom of the gravity separation vessel. 
   
   
       6 . The method of  claim 1 , wherein the gas liquid separation vessel is located near the bottom of a body of water.