GB2139977A

GB2139977A - Semi-submersible marine platform

Info

Publication number: GB2139977A
Application number: GB08310042A
Authority: GB
Inventors: Alexander George Copson
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-04-13
Filing date: 1983-04-13
Publication date: 1984-11-21
Also published as: GB8310042D0

Abstract

A semi-submersible marine platform has mounted underwater a guide (6) for a running mooring line (3) extending therethrough between a winch (7) or the like on the rig and a mooring buoy (5), the mooring line (3) carrying between the guide (6) and buoy (5) a line stop engageable with the guide (6) on drawing in of the line (3) so that the stop, the buoy (5) and the line therebetween constitute a single point mooring. <IMAGE>

Description

SPECIFICATION Semi-submersible marine plafform The present invention relates to a semi-submersible marine platform (hereinafter frequently termed a rig) which can remain on station (preferably dynamically positioned) not only for and during well fracing, reservoir stimulation and extensive well testing but also for and during flowing of oil from the well to a tanker.

For this purpose the rig has mounted underwater a guide for a running mooring line extending therethrough between a winch or the like on the rig and a mooring buoy, the mooring line carrying between the guide and buoy a line stop engageable with the guide on drawing in of the line so that the engaged line and stop, the buoy and the line therebetween constitute a single point mooring. The invention relates not only to the rig in combination with a winch, line, mooring buoy etc., but also the rig per se when fitted with the mooring line guide.

An embodiment of the invention is illustrated by way of example in the accompanying drawings in which: Figure 1 is an elevation view of the rig; and Figure 2 is a plan view on Figure 1.

Referring to Figures 1 and 2 a small semisubmersible rig (1) is dynamically positioned over a test well head. The rig has facility for the storage of fracing chemicals (9), the stimulation of the reservoir and the subsequent flowing of oil to surface.

The rig (1 ) has a rigid cross-member (2) mounted at the rear between the buoyancy pontoons (10) and extending some distance beyond the furthest extent of the upper rig structure (11). In this preferred embodiment the mooring line (3) is a chain although it could equally well be partly chain, partly hawser or all hawser. The mooring buoy (5) has a catch line attached and the chain (3) is let out through the line guide (6) by the winch mechanism (7). The catch line is taken up by an approaching small tanker (4) (e.g.

DWT 40000) and a bow hawser is attached to the buoy (5). The chain (3) is winched in and the tanker (4) is drawn towards the rig (1). The mooring chain (3) is fitted with a chain stop, at a predetermined distance from the buoy (5), which engages with the mooring line guide (6) and prevents further inward winching of the chain (3).

In one preferred embodiment the chain stop is a cone shaped fixture on the chain which may be varied in distance from the mooring buoy, and the line guide is cup shaped so that the chain stop mates with the guide when the buoy is at a predetermined distance from the guide thereby constituting a single point mooring system.

The tanker (4) exerts a small backward thrust, by means of its engines, which is balanced by the tendancy of the buoy to float in an upright position.

The tanker is thus moored at a predetermined distance from the rig (1). The coming and going of tankers does not interfere with the positioning or operation of the rig (1). Oil is transferred from the rig (1) to the tanker by means of a flexible floating hose (8). In the event of accident or adverse weather conditions the flexible floating hose (8) is released and the mooring chain (3) let out to allow rapid separation of tanker (4) and rig (1).

1. Asemi-submersible marine platform which has mounted underwater a guide for a running mooring line extending therethrough between a winch or the like on the rig and a mooring buoy, the mooring line carrying between the guide and buoy a line stop engageable with the guide on drawing in of the line so that the engaged line and stop, the buoy and the line therebetween constitute a single point mooring.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

SPECIFICATION Semi-submersible marine plafform The present invention relates to a semi-submersible marine platform (hereinafter frequently termed a rig) which can remain on station (preferably dynamically positioned) not only for and during well fracing, reservoir stimulation and extensive well testing but also for and during flowing of oil from the well to a tanker.

For this purpose the rig has mounted underwater a guide for a running mooring line extending therethrough between a winch or the like on the rig and a mooring buoy, the mooring line carrying between the guide and buoy a line stop engageable with the guide on drawing in of the line so that the engaged line and stop, the buoy and the line therebetween constitute a single point mooring. The invention relates not only to the rig in combination with a winch, line, mooring buoy etc., but also the rig per se when fitted with the mooring line guide.

An embodiment of the invention is illustrated by way of example in the accompanying drawings in which: Figure 1 is an elevation view of the rig; and Figure 2 is a plan view on Figure 1.

Referring to Figures 1 and 2 a small semisubmersible rig (1) is dynamically positioned over a test well head. The rig has facility for the storage of fracing chemicals (9), the stimulation of the reservoir and the subsequent flowing of oil to surface.

The rig (1 ) has a rigid cross-member (2) mounted at the rear between the buoyancy pontoons (10) and extending some distance beyond the furthest extent of the upper rig structure (11). In this preferred embodiment the mooring line (3) is a chain although it could equally well be partly chain, partly hawser or all hawser. The mooring buoy (5) has a catch line attached and the chain (3) is let out through the line guide (6) by the winch mechanism (7). The catch line is taken up by an approaching small tanker (4) (e.g.

DWT 40000) and a bow hawser is attached to the buoy (5). The chain (3) is winched in and the tanker (4) is drawn towards the rig (1). The mooring chain (3) is fitted with a chain stop, at a predetermined distance from the buoy (5), which engages with the mooring line guide (6) and prevents further inward winching of the chain (3).

In one preferred embodiment the chain stop is a cone shaped fixture on the chain which may be varied in distance from the mooring buoy, and the line guide is cup shaped so that the chain stop mates with the guide when the buoy is at a predetermined distance from the guide thereby constituting a single point mooring system.

The tanker (4) exerts a small backward thrust, by means of its engines, which is balanced by the tendancy of the buoy to float in an upright position.

The tanker is thus moored at a predetermined distance from the rig (1). The coming and going of tankers does not interfere with the positioning or operation of the rig (1). Oil is transferred from the rig (1) to the tanker by means of a flexible floating hose (8). In the event of accident or adverse weather conditions the flexible floating hose (8) is released and the mooring chain (3) let out to allow rapid separation of tanker (4) and rig (1).

1. Asemi-submersible marine platform which has mounted underwater a guide for a running mooring line extending therethrough between a winch or the like on the rig and a mooring buoy, the mooring line carrying between the guide and buoy a line stop engageable with the guide on drawing in of the line so that the engaged line and stop, the buoy and the line therebetween constitute a single point mooring.