Communication apparatus comprises a first transceiver unit (205A) and a signal processing device (106) configured to receive a signal from the first transceiver unit and to produce a signal for transmission by the first transceiver unit. A cable (201A) connects the first transceiver unit to the signal processing device. The first transceiver unit comprises a housing; a first pair of transducers (204T, 204R) located at, or adjacent, a first end of the housing, and a second set of transducers (206T, 206R) located at, or adjacent, an opposite end of the housing.

A method transports and installs a heavy subsea structure such as a subsea processing center for produced crude oil or natural gas. The method includes controlledly flooding at least one ballast tank attached to or incorporated into the structure to the extent that the structure becomes negatively buoyant at a pre-determined towing depth. The method also includes towing the negatively-buoyant structure at the towing depth by the Controlled Depth Towing Method (CDTM). After towing to the installation location, the method includes further flooding the ballast tank to lower the structure onto the seabed. At the seabed, a fluid transportation pipe of a subsea production installation may be coupled to pipework of the structure.

The invention provides a flow system, a subsea valve (100), and a method of use in a subsea pipeline filling, flooding or pigging operation. The flow system comprises a subsea valve (100) comprising a valve inlet and a valve outlet configured to be coupled to a subsea pipeline (13). A pump (112) comprises a pump inlet connected to a fluid source and a pump outlet connected to the valve inlet. The pump is operable to pump fluid from the fluid source and into the subsea pipeline via the subsea valve. The subsea valve comprises a movable valve member and a biasing mechanism, by which the valve member is urged by a biasing force towards a closed position that prevents flow of fluid through the valve and into the subsea pipeline. The valve member is operable to be moved to an open position on activation of the pump to provide a pressure increase at the valve inlet sufficient to overcome the biasing force. In use, opposing sides of the valve member are exposed to ambient subsea pressure such that the subsea valve is pressure balanced.

A retrievable subsea apparatus (1) with a pressure and volume compensating system, the apparatus comprising: a housing (1′) having in its interior a control system (9) located in a first section (3) thereof and an operating unit (6) located in a second section (4) thereof. The apparatus further comprises a penetrator (2) which constitutes an interface between the first section (3) and the second section (4), wherein the first section (3) has a substantially constant first pressure. An external pressure compensator (5, 5′) is associated with the second section (4) having a second pressure. The operating unit (6) comprises at least a first sub-unit (6′) and at least a second sub-unit (6″). The second section (4) is subdivided into at least a first sub-section (4′) and at least a second sub-section (4″) which is sealed off from the first 1,1 section (4′) and being associated with respective sub-unit (6′, 6″).

A method for treating the formation of hydrates in a fluid system includes pumping a fluid at a substantially constant fluid flow rate through a hydrate removal system including a pressure modulator, communicating a vacuum pressure to a piece of subsea equipment from a pressure port of the pressure modulator, closing a valve in the hydrate removal system to cease the fluid flow through the hydrate removal system at the substantially constant fluid flow rate, and communicating a positive pressure greater than the vacuum pressure to the piece of subsea equipment in response to closing the valve of the hydrate removal system.

Techniques and systems to provide additional holding ability to a subsea wellhead system. A device includes an auxiliary frame that may be coupled to an outer portion of a BOP frame that encloses at least a portion of a BOP. The auxiliary frame may also house a plurality of accumulators that may be used to provide pressurized fluid to the BOP.

A fluid system includes a pumping flowline, wherein the pumping flowline is in selectable fluid communication with a production flowline, a cylinder including a first port and a second port, a piston slidably disposed in the cylinder, the piston sealing against an inner surface of the cylinder to form a first chamber and a second chamber, wherein the first chamber is in fluid communication with the first port and the second chamber is in fluid communication with the second port, and a first flowline in fluid communication with the first port of the cylinder and the pumping flowline, the first flowline including a first flowline valve, wherein, in response to opening the first flowline valve, the piston is displaced through the cylinder in a first direction to expand a volume of the first chamber of the cylinder.

A system and method is provided for converting a drilling rig between conventional hydrostatic pressure drilling and managed pressure drilling or underbalanced drilling using a docking station housing mounted on a marine riser or bell nipple. This docking station housing may be positioned above the surface of the water. When a removable rotating control device is remotely hydraulically latched with the docking station housing, the system and method allows for interactive lubrication and cooling of the rotating control device, as needed, along with a supply of fluid for use with active seals.

A system, in certain embodiments, includes a power supply. The power supply includes an ultracapacitor configured to be charged by a DC source. The power supply also includes a first switch that enables charging of the ultracapacitor by the DC source when in a closed position and disables charging of the ultracapacitor when in an open position. The power supply further includes a second switch configured to enable discharging of the ultracapacitor when in a closed position and to disable discharging of the ultracapacitor when in an open position. As the ultracapacitor is discharged, a current is supplied to actuate a shape memory alloy element.

A flow management system includes an adjustable compactor configured for attachment to a wall surface of a conduit and being adjustable between an extended configuration and a reference configuration, an electric actuator in fluid communication with the adjustable compactor, and a control module. The control module is configured to control the electric actuator to flow a current to the adjustable compactor to generate an electric field that causes extension of the adjustable compactor for compacting a flow blockage within the conduit to create a channel adjacent the flow blockage and to terminate a flow of the current to remove the electric field at the adjustable compactor to cause the adjustable compactor to return to the reference configuration for opening the channel to a fluid flow within the conduit.