A method for compensating the bathymetric pressure inside a subsea tank containing a liquid working fluid by using a bathymetric compensation fluid is provided. The liquid working fluid and the bathymetric compensation fluid are separated from each other by a separation layer of a separation fluid.

An underwater storage tank having a flexible multilayer tank containing a working liquid is provided. The flexible multilayer tank has at least one internal electrical insulating layer in contact with the working fluid, at least one external electrical insulating layer in contact with sea water, and at least one intermediate electric conductive layer sealed between the at least one internal electrical insulating layer and the at least one external electrical insulating layer. At least one first electrical connection means is connected to the at least one intermediate electric conductive layer, the least one first electrical connection means being electrically connectable to an electrical grounded measurement instrument to assess physical integrity of the flexible multilayer tank.

An underwater storage tank having a flexible multilayer tank containing a working liquid is provided. The flexible multilayer tank has at least one internal electrical insulating layer in contact with the working fluid, at least one external electrical insulating layer in contact with sea water, and at least one intermediate electric conductive layer sealed between the at least one internal electrical insulating layer and the at least one external electrical insulating layer. At least one first electrical connection means is connected to the at least one intermediate electric conductive layer, the least one first electrical connection means being electrically connectable to an electrical grounded measurement instrument to assess physical integrity of the flexible multilayer tank.

It is described cylindrical subsea vessel (1) for separation of a flow, the vessel (1) comprising first and second longitudinal ends (T,1″), wherein the subsea vessel (1) comprises: —a liner (2); —at least one fluid inlet (3) and one fluid outlet (4, 5) into and out of an inner volume (7) of the vessel (1); —at least one flange (8) connected in one of the longitudinal ends (1′, 1″), wherein the at least one flange (8) and the liner (2) form the inner volume of the subsea vessel (1), and wherein the at least one flange (8) comprises at least one through-going opening (4,5,6) forming the at least one fluid inlet (3,4) and/or fluid outlet (5); —a load bearing structure (9) arranged outside the liner (2) and the at least one flange (8), wherein the load bearing structure (9) is of a composite material. It is further described a method of manufacturing the subsea vessel.

It is described cylindrical subsea vessel (1) for separation of a flow, the vessel (1) comprising first and second longitudinal ends (T,1″), wherein the subsea vessel (1) comprises: —a liner (2); —at least one fluid inlet (3) and one fluid outlet (4, 5) into and out of an inner volume (7) of the vessel (1); —at least one flange (8) connected in one of the longitudinal ends (1′, 1″), wherein the at least one flange (8) and the liner (2) form the inner volume of the subsea vessel (1), and wherein the at least one flange (8) comprises at least one through-going opening (4,5,6) forming the at least one fluid inlet (3,4) and/or fluid outlet (5); —a load bearing structure (9) arranged outside the liner (2) and the at least one flange (8), wherein the load bearing structure (9) is of a composite material. It is further described a method of manufacturing the subsea vessel.

A modular subsea fluid storage unit has a variable-volume inner tank having a rigid top panel and a peripheral wall that is flexible by virtue of concertina formation. The peripheral wall is extensible and retractable vertically while the horizontal width of the tank remains substantially unchanged. A side wall of a lower housing part surrounds and is spaced horizontally from the peripheral wall of the inner tank to define a floodable gap between the peripheral wall and the side wall that surrounds the tank. An upper housing part extends over and is vertically spaced from the top panel of the inner tank and overlaps the side wall to enclose the inner tank. The floodable gap and the upper housing part enhance thermal insulation and trap any fluids that may leak from the inner tank.

A modular subsea fluid storage unit has a variable-volume inner tank having a rigid top panel and a peripheral wall that is flexible by virtue of concertina formation. The peripheral wall is extensible and retractable vertically while the horizontal width of the tank remains substantially unchanged. A side wall of a lower housing part surrounds and is spaced horizontally from the peripheral wall of the inner tank to define a floodable gap between the peripheral wall and the side wall that surrounds the tank. An upper housing part extends over and is vertically spaced from the top panel of the inner tank and overlaps the side wall to enclose the inner tank. The floodable gap and the upper housing part enhance thermal insulation and trap any fluids that may leak from the inner tank.

An aquatic transportation, storage, and distribution system, including one or more storage containers and a guide structure. The storage container is capable of retaining one or more items therein and is configured to selectively vary the buoyancy thereof to urge the storage container to float up or sink down within an aquatic environment. The guide structure is supported at least partially within the aquatic environment and includes at least one non-horizontal segment. The storage container is configured to interact with the at least one segment as the storage container is urged to float up or sink within the aquatic environment such that the storage container is moved along the guide structure and is routed to a specified extraction point for retrieval from the aquatic environment.

An aquatic transportation, storage, and distribution system, including one or more storage containers and a guide structure. The storage container is capable of retaining one or more items therein and is configured to selectively vary the buoyancy thereof to urge the storage container to float up or sink down within an aquatic environment. The guide structure is supported at least partially within the aquatic environment and includes at least one non-horizontal segment. The storage container is configured to interact with the at least one segment as the storage container is urged to float up or sink within the aquatic environment such that the storage container is moved along the guide structure and is routed to a specified extraction point for retrieval from the aquatic environment.

A high-performance seafloor flexible oil storage system, solving the existing problems of high storage cost and difficult maintenance of crude oil in offshore oilfields, comprises, sequentially connected, an oil-water separator, a pressure pump, and an input riser extending downward below the sealevel; and a pipeline and multiple flexible oil storage tanks having the same structure with each communicated therewith through a control valve are arranged below the sealevel. One end of the pipeline is communicated with the input riser through a blocking valve and an input valve, and the other end further sequentially connected with an outlet booster pump, an output valve, and an output riser extending upwards above the sealevel and connected to a tanker through a cooler and an output pump. The flexible oil storage tank has a concrete counterweight connected thereunder for fixing it to a seabed. The system has simple structure, convenient maintenance and good practicability.