Riser with retrievable internal services
OwnerBrendan Paul Herd, Ben Seymour +1inventors
InventorsBrendan Paul Herd, Ben Seymour, William Eric Abraham
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Abstract
Systems are described for raising production fluid from a source (1) on the seabed comprising a riser (4) having a first, lower, end for connection or connected to the source; a top end support for supporting the riser at or in the vicinity of the sea surface; and an operating device (11) mounted inside the riser (4) for displacement within the riser so that the pump is accessible to an operator for replacement or repair. The operating device (11) may be displaced on a pipe (12) which extends within the riser (4) and to a lower end of which the device (11) is attached. The device (11) may be inter alia an electric pump, a hydraulic pump, a gas injector, a heater or a cleaning device.
Claims43
A system for raising production fluid from a source on the seabed, comprising:—
- a riser having an internal passageway for conveying said production fluid and having a first, lower, end for connection to or
- a top end support for supporting the riser at its second end at or in the vicinity of the sea surface;
- and
- an operating device mounted inside the riser for displacement within the riser between a first, operating, position in the riser remote from its second end, and a second, access, position, at the second end of the riser, so that the device is accessible for replacement or repair, the operating device being a pump or a gas injector.
A system according to any preceding claim, wherein a pig introducing device is provided for introducing a pig into the riser at a position below the operating device when in said second position.
A system according to any preceding claim, further comprising a locating device which is mounted on the operating device, and is selectively operable for (i) engaging with the inner surface of the riser and (ii) disengaging therefrom so that the operating device can be repositioned in the riser.
A system according to any preceding claim, wherein in addition to said passageway for carrying the production fluid, a second passageway is provided in the riser for connection to a low pressure region in the vicinity of the upper end of the riser and means are provided for expelling production fluid from the first passageway to said low pressure region, so as to reduce the pressure in the first passageway to a lower value than the existing under interrupted on shutdown conditions, thereby inhibiting formation of solid hydrates in the first passageway.
A system according to any one of the preceding claims, wherein said riser has a lazy-S, steep wave or steep-S configuration.
A method of installing an operating device in a riser connecting a source of production fluid on the seabed to a top end support supporting the riser at or in the vicinity of the sea surface, the operating device being a pump or a gas injector, the method comprising:—
- (a) introducing the device into the riser at the upper end thereof;
- and
- (b) driving the device downwardly into the riser to a desired operating position in the riser remote from its end at the top end support.
Dependencies are inferred from the claim text.