A subsea multiphase fluid separation system has a gas separator for separating gas from a well stream containing oil. A water separation stage downstream of the gas separator has at least one dual pipe separator for separating water from the oil of the wellstream. A water treatment system for cleaning oil from water is produced by the water separation stage. On an oil outlet path, downstream of the or each dual pipe separator, there is an electrocoalescer and at least one second separator in series.

A subsea multiphase fluid separation system has a gas separator for separating gas from a well stream containing oil. A water separation stage downstream of the gas separator has at least one dual pipe separator for separating water from the oil of the wellstream. A water treatment system for cleaning oil from water is produced by the water separation stage. On an oil outlet path, downstream of the or each dual pipe separator, there is an electrocoalescer and at least one second separator in series.

A subsea fluid processing system which receives a wellstream flow. The subsea fluid processing system includes a pressure control device which regulates a pressure of the wellstream flow, a gas-liquid separator unit which receives the wellstream flow downstream of the pressure control device and which provides a liquid stream and a gas stream, a first membrane separator which receives the gas stream and which provides a retentate stream and a permeate stream, a compressor which receives the permeate stream and which provides a compressed permeate stream, and a discharge cooler which receives the compressed permeate stream and which provides a cooled compressed permeate stream for injection into a subsurface reservoir. A density of the cooled compressed permeate stream is higher than a density of the compressed permeate stream.

A subsea fluid processing system which receives a wellstream flow. The subsea fluid processing system includes a pressure control device which regulates a pressure of the wellstream flow, a gas-liquid separator unit which receives the wellstream flow downstream of the pressure control device and which provides a liquid stream and a gas stream, a first membrane separator which receives the gas stream and which provides a retentate stream and a permeate stream, a compressor which receives the permeate stream and which provides a compressed permeate stream, and a discharge cooler which receives the compressed permeate stream and which provides a cooled compressed permeate stream for injection into a subsurface reservoir. A density of the cooled compressed permeate stream is higher than a density of the compressed permeate stream.

A subsea fluids storage facility comprises a tank for holding and separating fluids which is equipped with ballast capacity and a separable base to be deployed upon the seabed in shallow or deep water, and the storage facility is connectable to a surface production facility, especially a buoy for processing fluids. In deep water the tank is held at a depth above the base for temperature controlled stabilization of produced oil in the tank.

A subsea fluids storage facility comprises a tank for holding and separating fluids which is equipped with ballast capacity and a separable base to be deployed upon the seabed in shallow or deep water, and the storage facility is connectable to a surface production facility, especially a buoy for processing fluids. In deep water the tank is held at a depth above the base for temperature controlled stabilization of produced oil in the tank.

A subsea separator vessels includes single machined blocks integrated into a hull so as to combine all the valves used in the process of separating the multiphase fluid in the interior of the blocks. The separator vessels have by-pass valves in their blocks, if necessary to interrupt the separation process. The blocks function as a structure for the separating vessels, thereby replacing all of the metal structure necessary to support the tubes and valves of a conventional manifold, thus reducing the total area occupied by the separation station in the seabed.

A subsea separator vessels includes single machined blocks integrated into a hull so as to combine all the valves used in the process of separating the multiphase fluid in the interior of the blocks. The separator vessels have by-pass valves in their blocks, if necessary to interrupt the separation process. The blocks function as a structure for the separating vessels, thereby replacing all of the metal structure necessary to support the tubes and valves of a conventional manifold, thus reducing the total area occupied by the separation station in the seabed.

A subsea hydrocarbon flow compression system (100) for receiving a hydrocarbon stream from at least one upstream flowline (102, 104) and supplying the hydrocarbon stream to at least one downstream flowline (106, 108) at an increased pressure, wherein the compression system comprises first and second compressor trains (110a, 110b), wherein each compressor train comprises an inlet port (112a, 112b) which is connectable to the at least one upstream flowline (102, 104); an outlet port (114a, 114b) which is connectable to the at least one downstream flowline (106, 108); a conditioning unit (116a, 116b) which is connected to the inlet port via a first flowline (118a, 118b); and a first flow path for the hydrocarbon fluid comprising a compressor (120a, 120b), which compressor is connected to the conditioning unit via a second flowline (122a, 122b) and to the outlet port via a third flowline (124a, 124b), wherein a controllable first valve (126) is arranged in the third flowline of the first compressor train for controlling hydrocarbon flow from the compressor to the outlet port of the first compressor train. A controllable second valve (128) is arranged in the second flowline of the second compressor train for controlling hydrocarbon flow from the conditioning unit to the compressor of the second compressor train. The system further comprises a first cross-over flowline (130) interconnecting the third flowline of the first compressor train upstream of the first valve and the second flowline of the second compressor train downstream of the second valve, wherein a controllable first cross-over valve (132) is arranged in the first cross-over flowline for controlling hydrocarbon flow through the first cross-over flowline.

The disclosure discloses a solid fluidization tubular separator for marine natural gas hydrate, which includes a first separator and a second separator, wherein the first separator includes the first separation sleeve, the power liquid pipe, the swirl baffle, the recovery mechanism and the sand discharge mechanism. After the hydrate is sucked into the first separation sleeve to generate a circumferential velocity, so that the mud and sand with high density are separated to the pipe wall of the first separation sleeve, and the mud and sand separated to the pipe wall are settled down from the gap between the swirl baffle and the pipe wall along the pipe wall. The hydrate swirl flows into the recovery mechanism, and then leaves the first separation sleeve and enters the second separator, so as to realize the separation of mud and sand and natural gas hydrate.