Method and arrangement for treatment of fluid
AssigneeAker Kvaerner Subsea AS
InventorsGeir Inge Olsen, Gunder Homstvedt
Life of this patent
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Abstract
The present invention relates to methods and arrangements for utilising the energy of water that flows out from a high-pressure reservoir. Water and hydrocarbons are separated in a down-hole separator (3) and are brought separately to the seabed. In a first aspect the energy of the water is utilised to inject the water into an underground formation (28) with a lower pressure. In a second aspect the energy is utilised to drive a turbine which in turn is driving a pump (32) for pressurising hydrocarbons. As a part of the invention a method and an arrangement to control the separator (3) by control valves (7, 8) on the well head (6) for each phase is provided. In a further aspect a higher water pressure is provided by gas lift.
Claims15
Method of producing reservoir fluid from a hydrocarbon containing underground reservoir, characterised in the combination of the following steps:
- separating the reservoir fluid downhole into at least a hydrocarbon phase and a water phase,
- bringing the hydrocarbon phase and the water phase separately to a subsea wellhead,
- injection of the water phase into an underground formation through a subsea wellhead, e.g. for disposal, pressure maintenance or sweeping, utilising at least partly the inherent pressure in the water.
Method of producing reservoir fluid from a hydrocarbon containing underground reservoir, characterised in the combination of the following steps:
- separating the reservoir fluid downhole into at least a hydrocarbon phase and a water phase,
- bringing the hydrocarbon phase and the water phase separately to a subsea wellhead,
- utilising at least partly the inherent pressure in at least one of the phases to power at least one turbine, pump, compressor or separator located at the seafloor.
Method of controlling a downhole separator for separating the reservoir fluid into at least two phases, a hydrocarbon phase and a water phase, whereby the at least two phases are brought separately to a subsea wellhead, characterised in that the hydrocarbon phase is led through a first control valve and the water phase is led through a second control valve, which are located at the seabed, that at least one of the following parameters are measured:
- separator interface level, flow-split, differential pressure across the separator or phase purity, and that at least one of the control valves are regulated as a function of said at least one parameter to increase or decrease the flow rate of hydrocarbons or water from the separator, to maintain said at least one parameter within predefined limits.
Method of producing reservoir fluid from a hydrocarbon containing underground reservoir, wherein the reservoir fluid is separated downhole, at least into a hydrocarbon phase and a water phase, and brought separately to a subsea wellhead, characterised in providing a gas phase with a higher pressure than the water phase at a downhole injection level, injecting the gas phase into the water phase at the injection level, to apply the gas phase for artificial lift of the water phase.
Method according to claim 11, characterised in that the gas phase for artificial lift is supplied from a distant source.
- Method according to claim 11, 12, 13, 14 or 15, characterised in that the water is injected into an underground formation together with the gas used for atrificial lift.
- Method according to claim 11, 12, 13, 14 or 15, characterised in that the gas is separated from the water, and that the water is disposed to seawater, optionally after polishing.
- Arrangement for producing reservoir fluid from a hydrocarbon containing underground reservoir, characterised in that the arrangement comprising a downhole hydrocarbon-water separator (3), a wellhead (6) coupled to the separator (3), a subsea means (17, 21, 24, 25, 26) for injection of the water into an underground formation (28) coupled to the wellhead (6).
- Arrangement according to claim 17, characterised in that the arrangement further comprising a pump (29) coupled to said means (17, 21, 24, 25, 26) for pressurising the water before injection of the water into an underground formation (28).
- Arrangement for producing reservoir fluid from a hydrocarbon containing underground reservoir, characterised in that the arrangement comprising a downhole hydrocarbon-water separator (3), a wellhead (6) coupled to the separator (3), a hydrocarbon line (12) coupled to the wellhead (6), a water line (17) coupled to the wellhead (6), a turbine (31), pump, compressor or separator coupled to one of the hydrocarbon line (12) or the water line (17), to be powered by the hydrocarbon or water of that line (12, 17).
- Arrangement according to claim 19, characterised in that the water line (17) being coupled to a turbine (31), the hydrocarbon line (12) being coupled to a pump (32), the turbine (31) being coupled to the pump (32).
- Arrangement according to claim 19, characterised in that the water line (17) being coupled to a pump (32), the hydrocarbon line (12) being coupled to a turbine (31), the turbine (31) being coupled to the pump (32).
- Arrangement according to claim 19, characterised in that the water line (17) being coupled to a turbine (31), the turbine (31) being coupled to a compressor for pressuring gas.
- Arrangement according to claim 19, characterised in that the water line (17) being coupled to a separator (40), for degassing the water.
- Arrangement for controlling a downhole separator (3) for separating the reservoir fluid into at least two phases, a hydrocarbon phase and a water phase, comprising a hydrocarbon tubing (4) between the separator (3) and a wellhead (6) and a water tubing (5) between the separator (3) and the wellhead (6), characterised in a first control valve (8) at the wellhead, a second control valve (7) at the wellhead (6), the hydrocarbon tubing (4) being coupled to the first control valve (8), the water tubing (5) being coupled to the second control valve (7);
- a measuring means for measuring at least one of the following:
- separator interface level, flow-split, differential pressure across the separator or phase purity;
- a regulating means for regulating the first and/or the second control valves (7, 8) to increase or decrease the flow rate of hydrocarbons or water from the separator, to maintain said at least one parameter within predefined limits.
- Arrangement for producing reservoir fluid from a hydrocarbon containing underground reservoir, characterised in that the arrangement comprising a downhole hydrocarbon-water separator (3), a wellhead (6), a hydrocarbon tubing (4) between the separator (3) and the wellhead (6) and a water tubing (5) between the separator (3) and the wellhead (6), a hydrocarbon line (12) coupled to the hydrocarbon tubing (4) at the wellhead (6), a water line (17) coupled to the water tubing (5) at the wellhead (6), a gas line (49) coupled to a gas tubing (48) at the wellhead, the gas tubing (48) being coupled to the water tubing (5) at a downhole injection point, for injection of gas to achieve artificial lift of the water.
- Arrangement according to claim 25, characterised in a separator coupled to the hydrocarbon line (12), for separating gas from the hydrocarbons.
- Arrangement according to claim 25, characterised in a separator (40) coupled to the water line (12), for separating gas from the water.
- Arrangement according to claim 27, characterised in a compressor (49) coupled to the gas line (49), for compressing the gas.
- Arrangement according to claim 25, characterised in a gas supply line (50) coupled to the gas line (49).
Dependencies are inferred from the claim text.