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.

Systems and methods for containing a subsea flow of hydrocarbons includes a water intake. The water intake is operable to be positioned downstream of the subsea flow of hydrocarbons. A receiving facility is located at a surface of a sea. A suction hose extends from the water intake to the receiving facility. A suction system is operable to reduce a fluid pressure within the water intake.

A leak detection system includes an annular housing that defines a bore, a constriction with the bore, and a channel extending radially-outwardly from the bore and positioned upstream of the constriction. The leak detection system also includes a sensor positioned outside of the bore and fluidly coupled to the channel, wherein the sensor is configured to detect a leaked fluid within the bore.

According to one aspect, an apparatus is adapted to be operably coupled to a subsea blowout preventer and includes a first tubular member defining an internal passage, and a second tubular member extending within the internal passage. A sealing assembly is disposed radially between the first and second tubular members, and includes a sealing element. The second tubular member covers the sealing element and thus facilitates protecting the sealing element from any fluid flow through the internal passage. According to another aspect, a sealing element of a connector is protected before engaging the connector with a subsea casing. The connector is engaged with the casing while the sealing element is protected so that the sealing element is fluidically isolated from any fluid flow through the connector. The sealing element sealingly engages the casing.

A passive detection system is used for monitoring the integrity of abandoned, suspended, and/or decommissioned subsea wells or carbon dioxide sequestration reservoirs, where the system utilises a passive detector that reacts to the presence of a predetermined chemical to release a buoyant beacon. The beacon travels under buoyancy to the sea surface, where it transmits signals to an operator to alert the operator to a potential loss of integrity at the site. The system can include a trigger that initially restrains the beacon, but degrades in response to contact with the predetermined chemical. The system can include gathering and concentrating devices that collect the leaking chemical and direct the collected chemical towards the trigger, facilitating contact between the chemical and trigger and resulting degradation. Once the trigger has degraded sufficiently, it loses structural integrity and fails, releasing the beacon.

A petroleum pipeline safety system for preventing contamination of an environmentally sensitive area close to a pipeline includes an upstream portion of the pipeline supplying a flow of fluid material, a crossing portion of the pipeline receiving the flow of fluid material from the upstream portion and conveying the flow of fluid material through the environmentally sensitive area to a downstream portion of the pipeline, the downstream portion, a pipeline pressure activated valve selectively capable of blocking the flow of fluid material from entering the crossing portion based upon a change in pressure within the crossing portion, and a fluid capacitor connected to the upstream portion configured to filter out a pressure spike in the upstream portion associated with the valve blocking the flow of fluid material.

A method for producing a methane-rich gas from a heavy hydrocarbon feed, the method comprising the steps of introducing the heavy hydrocarbon stream to a catalytic reactor, the catalytic reactor comprising an activated catalyst, the activated catalyst comprising 20 wt % of nickel, 70 wt % of a cerium oxide component, and 10 wt % of a gadolinium oxide component; applying the heavy hydrocarbon stream to the activated catalyst; and producing the methane-rich gas over the activated catalyst, wherein the methane-rich gas is selected from the group consisting of methane, carbon dioxide, carbon monoxide, hydrogen, and combinations of the same.

The disclosure provides a downhole completion device for use in a wellbore and a subterranean production well. In one embodiment, the downhole completion device includes: (1) a hydraulic line controlled device, the hydraulic line controlled device having a control line port and one or more fluid leakage paths, and (2) a density barrier having first and second ends, wherein the first end is coupled to the control line port and the second end is configured to couple to a control line extending from a surface installation, the density barrier having an axial loop relative to the hydraulic line controlled device and positioned below the fluid leakage path, thereby preventing migration of leakage fluid from the one or more fluid leakage paths to the surface installation.

In a gas collecting method for collecting gas yielding from source material on a sea bottom, [1] releasing a collecting membrane into water, a fixture being connected with a lower end of the collecting membrane and the collecting membrane being flared downward from its top; [2] keeping a three-dimensional position of the fixture at a target position with its autonomous navigation by a position maintainer provided in the fixture; [3] based on vertical water temperature distribution, setting the lower end at a position that is higher than the sea bottom and shallower than a water depth where the source material separates from its solid state into water and gas and setting the top at a deeper position than a water depth where bubbles of the gas disappear due to mixture of the gas with seawater; and [4] collecting the gas released from the sea bottom by the collecting membrane.

A method of identifying hydrocarbon seeps that are connected to hydrocarbon reservoirs and for identifying in situ conditions of hydrocarbon reservoirs is disclosed. The method comprises, obtaining a sample from an area of interest, such as a sediment sample or water column sample near a hydrocarbon seep; analyzing the sample to detect microbial signatures that are specific to families associated with hydrocarbon reservoirs; and using the signature to determine whether the hydrocarbon seep is connected to a hydrocarbon reservoir and to identify properties of the hydrocarbon reservoir.