SUBSEA SYSTEM FOR PRESSURIZATION AND METHOD FOR ALTERNATE SWITCHING OF INJECTION FLUID, FROM WATER TO GAS, IN A SATELLITE WELL PROVIDED WITH A SINGLE SUBSEA INJECTION LINE

摘要

The present invention relates to the injection of water and gas, alternately, into subsea wells in order to increase production and the oil recovery level. To this end, the present invention provides a subsea system for pressurization of a subsea oil reserve through the separate injection of water and gas, comprising (i) a subsea injection well (4), connected to a production unit (3) by means of an individual subsea line (2) and (ii) an interface with a drain (13) integrated into the wet Christmas tree assembly (5) of the injection well (4) and optionally (iii) a hydro-electric umbilical (2) provided with an HCR line (9) and optionally (iv) a nitrogen injection point in the top of the injection column (15) of the injection well (4). The present invention also provides a method for switching (changing) the injected fluid, between water and gas, through the displacement with an inert gas (nitrogen) and possible emptying of the injection line (2), before the switch to the other fluid.