CN117622381A - Oilfield development facility with mooring and streamline system - Google Patents

Abstract

The present invention is an oilfield development facility having a system of both mooring and streamlines, the subsea streamlines being connected to a tanker serving as a floating storage facility by a system comprising a mooring and a flexible riser, the mooring means comprising an anchor connected to a common node by the anchor riser, and a mooring hanger extending from the node to the tanker, the flexible riser comprising a flexible rubber hose extending from the seabed to the tanker, a top portion of the hose being secured along a portion of the mooring hanger, a middle portion being buoyant and restrained by the tether to hold it away from the anchor riser.

Description

Oilfield development facility with mooring and streamline system

Technical Field

The invention discloses an oilfield development facility with a mooring and flow line system, which is particularly suitable for (but not limited to) mooring and loading of a production well or a floating outlet oil storage vessel for extended well testing. .

Background

Production of offshore wells initially goes to shore through subsea pipeline outlets, which requires a very large cost investment. Relatively currently the dominant approach is to develop more marginal fields by using floating production platforms and floating storage facilities from which tankers export oil periodically. Typically the floating storage facility is provided by retrofitting an existing tanker. Such systems work well, but there is still a need to significantly reduce installation costs to increase the economics of marginal oilfield production and to expand the economic viability of well testing.

The tanker refitting used so far requires a great deal of engineering. In some cases oil well producers use turret mooring, including swivel joints, requiring major structural work on the tanker in addition to the complex mooring turret. In other cases, the art has required quick connect disconnect valves by using flexible risers connected to the tanker, which physical size and weight requirements are mounted on a relatively large structure outboard of the bow of the tanker.

Disclosure of Invention

It is an object of the present invention to provide an improved mooring and flow line system which is relatively simple to install. It is another object of the present invention to provide a system that enables a conventional tanker to function as a floating reservoir with minimal structural changes, and therefore, the present invention provides a mooring and streamlining system comprising: means for mooring the floating storage and/or production vessel to the seabed, and a flowline connected to a production well or facility; the mooring means comprising at least two anchors in the seabed, a respective anchor riser extending from each anchor, each anchor riser having one end secured to its anchor and the other end secured to a common mooring node member, and mooring suspension means extending from the node members for connecting the vessel in use; the streamlines include subsea streamlines extending from the well or facility direction to the vicinity of the mooring, and flexible riser streamlines extending from the subsea streamlines to the vessel; wherein the flexible riser flowline is a continuous conduit, without a rotational coupling, and a portion of its length is fixed alongside at least a portion of the mooring suspension device.

Preferably, at least three of the anchors are angularly aligned; there are three anchors 120 ° apart from each other. By providing a portion with a floating flowline riser and by tethering the same portion to limit lateral movement, the flowline riser is properly remote from the anchor riser and node members.

The mooring hanger may comprise two parallel chains, one through each bow of the vessel. In a particularly preferred form of the invention, a conventional tanker is allowed to be used as a storage vessel with a minimum of conversion, parallel chain ties are attached to the inside of the tanker for connection to standard anchor chain stops or remote controlled release stops, flexible riser flowlines are run into the inside of the tanker through a chute with their inboard ends placed along the tanker deck, and quick connect/disconnect valve means are located on the tanker deck between the inboard ends of the riser and the tank manifold of the tanker.

Drawings

FIG. 1 shows a schematic side view of one embodiment of the present invention in use with an oil storage facility;

fig. 2 shows a plan view corresponding to fig. 1.

Description of the embodiments

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1 and 2, the tanker 10 is anchored to the seabed 12 by a three-leg anchoring system comprising anchors 14a, 14b, 14c, the anchors 14a, 14b, 14c being connected to the node 18 by risers 16a, 16b, 16c, and a mooring hanger 20 being secured from the node 18 to the tanker 10. The mooring point is located near the floating production platform (not shown) from which the oil is transported via flowlines. The flowline includes a seabed portion 22 and a flexible riser 24. The riser 24 has a central portion provided with a floating collar 26 and restrained by a tie 28 secured to a counterweight 30.

As shown in fig. 2, the mooring arrangement should ensure an angle of 120 ° to the vessel, while the streamlines approach along the bisector of the angle. This geometry, coupled with the float of collar 26 and the constraint of tether 28, keeps riser 24 from interfering with mooring node 18. The upper portion of riser 24 is secured along mooring hanger 20 by means of spaced double rings 32 and then brought to tanker 10 by means of a chute assembly shown at 34.

Claims (8)

1. An oilfield development facility having both mooring and flowline systems, characterized by: comprising a vessel, means for mooring the vessel, and a flow line fluidly connecting the vessel to the seabed means; the mooring comprises at least two anchors in the seabed, a respective anchor riser extending from each anchor, one end of each anchor riser being secured to the anchor and the other end being secured to a common mooring node member, the mooring node members being arranged in: any time during mooring; a mooring element having means for securing one end to the node member and directly connecting the other end to the vessel; the streamlines include seabed streamlines extending from the direction of the installation to the vicinity of the mooring, and flexible riser streamlines extending from the seabed streamlines to the sides of the vessel and on the vessel; wherein the flexible riser flowline is a continuous conduit without a swivel coupling and has a partial length of the flexible riser flowline fixed alongside at least part of the mooring suspension device.

2. An oilfield development facility having both mooring and streamlining systems of claim 1, wherein at least three anchors are angularly aligned; there are three anchors 120 ° apart from each other.

3. An oilfield development facility having both mooring and flowline systems in accordance with claim 1, wherein: the riser flowline is a fully bonded reinforced rubber structure wherein a portion of the flexible riser flowline is equipped with a floating device and in which a tether connects the device portion to the seabed.

4. An oilfield development facility having both mooring and flowline systems in accordance with claim 1, wherein: wherein there is no rotational coupling between the anchor and the vessel, wherein the node member comprises at least one flat ring connected to the anchor riser and the mooring suspension device by respective shackles.

5. An oilfield development facility having both mooring and flowline systems in accordance with claim 1, wherein: also included are a stop means for releasably securing the mooring suspension device and a fairlead means for receiving the mooring suspension device from overboard and guiding the mooring suspension device to said stop means, and a petroleum conduit terminating in a quick connect/disconnect valve means, and a chute for receiving and guiding a flexible riser adapted for installation in use.

6. An oilfield development having both mooring and streamlining system of claim 1, wherein the trough provides a guide surface between the valve means and a location outboard of the fairlead means, the guide surface allowing the hose thereon to flex horizontally and vertically and through the bow.

7. An oilfield development having both mooring and streamlining system of claim 1, the vessel being a tanker having the chute and valve apparatus on a midship of the vessel, wherein the mooring hanger comprises a double-stranded hanger, the fairlead apparatus comprises port and starboard fairleads of the double-stranded hanger, and the limiter apparatus comprises port and starboard tongue limiters.

8. An oilfield development having both mooring and streamlining systems of claim 1, the mooring hanger apparatus comprising two parallel chains, each chain passing through a respective side of the vessel bow to an anchor chain stop on the vessel, wherein the flexible riser streamlines pass through the vessel interior through a chute with all interior ends of the flexible riser streamlines disposed along the vessel deck.