A subsea oil over water storage tank, having one or multiple of high dynamic range, gas-liquid separators, which first receive oil well fluids, and cyclically depressurize and release free and solution gas to surface, and then expel unseparated liquids to the subsea storage tank, where the oil and water may be further separated by gravity separation, providing a means of separating stabilising crude oil.

A subsea oil over water storage tank, having one or multiple of high dynamic range, gas-liquid separators, which first receive oil well fluids, and cyclically depressurize and release free and solution gas to surface, and then expel unseparated liquids to the subsea storage tank, where the oil and water may be further separated by gravity separation, providing a means of separating stabilising crude oil.

Disclosed is a subsea storage unit (15; 15; 15) including a pressure hull (1) having a cargo hold (5) configured for storing cargo (3, 7) and a base (2; 8) configured for supporting the storage unit on a seabed (B). The pressure hull has a movable hatch (4), providing access to the cargo hold. The subsea storage unit also includes suspension means (11a,b, 35), wherein the subsea storage unit may be lifted and lowered in a body of water, and ballasting means. A seabed facility (30), configured for receiving and accommodating at least one subsea storage unit, is also provided.

Disclosed is a subsea storage unit (15; 15; 15) including a pressure hull (1) having a cargo hold (5) configured for storing cargo (3, 7) and a base (2; 8) configured for supporting the storage unit on a seabed (B). The pressure hull has a movable hatch (4), providing access to the cargo hold. The subsea storage unit also includes suspension means (11a,b, 35), wherein the subsea storage unit may be lifted and lowered in a body of water, and ballasting means. A seabed facility (30), configured for receiving and accommodating at least one subsea storage unit, is also provided.

The present invention relates to the use of compressed volatile organic compounds wholly or partly as a source of blanket gas for use in oil storage tanks, and methods and apparatus of providing same This includes a method of recovering and using VOC from one or more oil storage tanks comprising recovering, compressing and separating VOC from an oil storage tank, compressing the separated uncondensed VOC to provide a compressed VOC stream, and then heating and reducing at least a portion of the compressed VOC stream to provide a decompressed VOC stream for use as blanket gas in an oil storage tank. The present invention is able to prevent or substantially reduce reabsorption of captured VOC into stored oil. This also requires less (and possibly no) addition of extra inert gas during the oil discharge, and the next oil loading into the oil storage tank starts with a tank atmosphere that is very high in hydrocarbon content, thereby preventing formation of additional VOC during the next oil loading.

The present invention relates to the use of compressed volatile organic compounds wholly or partly as a source of blanket gas for use in oil storage tanks, and methods and apparatus of providing same This includes a method of recovering and using VOC from one or more oil storage tanks comprising recovering, compressing and separating VOC from an oil storage tank, compressing the separated uncondensed VOC to provide a compressed VOC stream, and then heating and reducing at least a portion of the compressed VOC stream to provide a decompressed VOC stream for use as blanket gas in an oil storage tank. The present invention is able to prevent or substantially reduce reabsorption of captured VOC into stored oil. This also requires less (and possibly no) addition of extra inert gas during the oil discharge, and the next oil loading into the oil storage tank starts with a tank atmosphere that is very high in hydrocarbon content, thereby preventing formation of additional VOC during the next oil loading.

This application discloses a new type of suction leg, an offshore caisson, a sit-on-bottom supporting platform. The suction leg includes a sealing long pile, this sealing long pile including a tubular pipe and a top head connected tightly to the tubular pipe to form cylindrical integral structure with sealing top and opening bottom. The top head has at least one opening to be able to open or close. The sealing long pile can be penetrated into the seabed by a gravity penetration method or/and a suction pile penetration method, or pulled out from the seabed by a buoyancy uplift method or/and a suction pile uplift method.

A liquid storage tank comprising an outer container wherein the outer container is rigid and has at least one inner container disposed within the outer container. The at least one inner container contains at least one stored liquid which may be refilled from a surface vessel or host facility. The at least one inner container is flexible and pressure balanced while the volume of the outer container remains fixed, and the volume of the at least one inner containers is variable. Disposed on the outer container is a balance assembly containing an isolation valve, a check valve, and a flexible bladder. The balance assembly allows for the hydrostatic pressure to be maintained during chemical dosing and tank raising operations.

A liquid storage tank comprising an outer container wherein the outer container is rigid and has at least one inner container disposed within the outer container. The at least one inner container contains at least one stored liquid which may be refilled from a surface vessel or host facility. The at least one inner container is flexible and pressure balanced while the volume of the outer container remains fixed, and the volume of the at least one inner containers is variable. Disposed on the outer container is a balance assembly containing an isolation valve, a check valve, and a flexible bladder. The balance assembly allows for the hydrostatic pressure to be maintained during chemical dosing and tank raising operations.

A steel plate and concrete composite tank unit, tank groups and offshore platforms with new type of tank units are disclosed. The tank unit comprises an outer concrete tank that comprises an outer tank shell, two heads and ring shell connections at both ends, an inner steel tank that comprises an inner tank shell, epitaxial structures at both ends of the inner steel tank. Inner tank shell is connected to the outer tank shell by epitaxial structures, and an isolation layer that is formed from the gap between the outer concrete tank and the inner steel tank where it is filled with isolation medium.