US 4,182,584 A · Marine production riser system and method of installing same

Abstract

A free-standing, marine production riser and a method of installing same for use in deep-water areas to conduct fluids between the marine bottom and the surface. The riser system is comprised of a lower rigid section and an upper flexible section. The lower rigid section has a casing extending from a preset base on the marine bottom to a point just below the zone of turbulence which exists near the surface of the water. A variable-buoyant buoy having a curved upper surface and a central passage therethrough is mounted on the upper end of the casing to support the casing in a substantially vertical position when the casing is in position on the preset base. A remotely actuated connector assembly is provided on the lower end of the casing for connecting the casing to the preset base. A plurality of conduits are run through the passage in the buoy and through guide means in the casing and are remotely connected to mating conduits on the base. Each of a plurality of flexible flowlines is connected to a respective conduit at a point within the passage in the buoy. Each of the flexible flowlines is of sufficient length to extend over the upper curved surface of the buoy which provides a natural bending radius for the flexible flowlines and then downward through a catenary loop before extending upward to the surface. The flowline length also will be sufficient to maintain a catenary loop in the flowline at all times during normal operating conditions. All of the upper ends of the flexible flowlines are connected to a single flange which, in turn, is adapted to be quickly connected to and disconnected from a floating facility at the surface. In turn, each flexible flowline can be individually installed and/or removed.

Claims19

Dependent claims

A marine riser system comprising:

a lower rigid section comprising:
a casing of sufficient length to extend from the marine bottom to a point just below the water zone near the surface which is affected by surface conditions,
a connector assembly attached to the lower end of said casing,
guide means on said connector assembly adapted to cooperate with means on a base element preset on the marine bottom to properly position said lower rigid section on the base element,
remotely actuated connector means on said connector assembly adapted to cooperate with means on the preset base element to secure said lower rigid assembly to the base element,
at least one conduit within said casing and extending throughout the length thereof, said conduit having a remotely actuated connector on its lower end adapted to couple said conduit to a mating member within the preset base element, and
a buoy mounted on the upper end of said casing, said buoy having sufficient buoyancy to support said lower rigid section in a substantially vertical position when said rigid section is in an operable condition;
and
an upper flexible section comprising:
at least one flexible flowline connected to said at least one conduit and extending in a curved path over said buoy and then downward through a catenary loop before extending upward to the surface, said flexible flowline being of sufficient length to maintain a catenary loop therein at all times during normal operating conditions.

7 more elements

A method of installing a marine riser system having a buoy-supported lower rigid section and an upper flexible section, the method comprising:

releasably mounting the lowermost element of said lower rigid section within a central passage which extends completely through said buoy;
towing said buoy and said lowermost element to the offshore installation site, using the buoyant force of said buoy to float same during towing;
passing a section of casing into said passage in said buoy and connecting said casing to said lowermost element of said lower rigid section;
releasing said lowermost element from said buoy;
continue connecting sections of casing to previously connected sections of casing and lowering said lowermost element on said connected sections of casing through said passage in said buoy until said lower rigid section is of a predetermined length;
lowering said lower rigid section and said buoy onto a preset base on the marine bottom;
connecting said lowermost element to said preset base;
transferring the buoyant force of said buoy to the upper end of said lower rigid section to support said lower rigid section in a substantially vertically position;
passing at least one flow conduit through said passage in said buoy and through said lower rigid section;
connecting said at least one flow conduit to a respective flow source on said preset base;
connecting one end of at least one flexible flowline to the upper end of said at least one flow conduit at a point within said passage in said buoy;
and
connecting the other end of said at least one flexible flowline to a floating facility on the surface.

10 more elements

Dependencies are inferred from the claim text.

Marine production riser system and method of installing same

Life of this patent

Marine production riser system and method of installing same

Life of this patent

Abstract

Claims19