Patent ID: 7854261

Claim:
A method of separating, in a production well, water from a water- and hydrocarbon-containing production flow emanating from at least one surrounding production formation; and of injecting, in the production well, a resulting water-containing liquid into at least one surrounding disposal formation, whilst a resulting hydrocarbon-containing liquid is produced out of the production well; in which the method comprises the following steps: (A) to arrange a first flow channel and a second flow channel within the production well, wherein: the first flow channel is structured to connect the production formation in a flow-communicating manner with an upstream side of at least one downhole water separation device; and the second flow channel is structured to connect the disposal formation in a flow-communicating manner with a downstream side of said downhole water separation device; (B) from the production formation, to direct the production flow via the first flow channel and further to said upstream side of the water separation device, at which upstream side the production flow has a pressure (P 1 ); (C) to arrange the second flow channel with an internal pressure manipulation region having a pressure (P 2 ), and being in pressure-communication with said downstream side of the water separation device; (D) in water suction mode, to adjust the pressure (P 2 ) in the pressure manipulation region to a pressure that is lower than the pressure (P 1 ) in the production flow; the action of which generates a pressure difference (P 1 -P 2 ) across the water separation device that sucks separated, water-containing liquid into the second flow channel, whilst hydrocarbons are retained in the water separation device and form said hydrocarbon-containing liquid; (E) to produce the hydrocarbon-containing liquid in the first flow channel out of the production well; and (F) via the second flow channel, to inject the water-containing liquid into the disposal formation under the influence of an injection pressure (P I ) that is higher than a total pressure (P T ) exerted by the disposal formation against the injection pressure (P I ), and which must be overcome to allow the water-containing liquid to be injected, wherein, in step (D), the pressure (P 2 ) is provided by means of the following steps: to connect the second flow channel with at least one external, first gas source; by means of gas from the first gas source, to form a first gas column having a gas pressure (P 3 ) in the second flow channel; to connect the first gas column in a pressure-communicating manner with the pressure manipulation region, whereby the gas pressure (P 3 ) in the first gas column corresponds with the pressure (P 2 ) in the pressure manipulation region; and in water suction mode, to adjust the gas pressure (P 3 ) in the first gas column to a pressure that is lower than the pressure (P 1 ) in the production flow, whereby the pressure (P 2 ) in the pressure manipulation region also is arranged correspondingly.