Double-layer underwater production supporting floating barrel and installation and recycling methods thereof

Abstract

The invention discloses a double-layer underwater production supporting floating barrel and installation and recycling methods thereof. The floating barrel comprises an outer floating barrel body and an inner floating barrel body, wherein the inner floating barrel body is nested in the outer floating barrel body. The outer floating barrel body is used for providing tension force of mooring cables, the inner floating barrel body is used for providing top tension force required by a rigid vertical pipe, accordingly, the double-layer floating barrel can conveniently and separately provide the top tension force required by the rigid vertical pipe and the mooring cables, and by applying the double-layer floating barrel in an ultra-deep ocean oil-gas project development system, the requirement for practical project application can be met. The perpendicular movement and stress of the rigid vertical pipe and the outer floating barrel body are decoupled, so that the stress and movement amplitude of the rigid vertical pipe are reduced, and the strength and fatigue performance of the rigid vertical pipe can be improved advantageously. The outer floating barrel body is moored on a seabed through the four mooring cables, when any one of the cables breaks off and fails, the other three cables can still maintain stability of the outer floating barrel body, and safety of the oil-gas development system is ensured.

Description

technical field [0001] The invention relates to a marine oil and gas development technology, in particular to a double-layer underwater production support buoy and its installation and recovery method. Background technique [0002] With the gradual depletion of oil and gas resources in the land, offshore and middle-deep seas, the exploitation of offshore oil is gradually moving towards the deep sea and ultra-deep sea. However, the existing floating production platforms and underwater production systems are difficult to apply in deep water and ultra-deep water environments. [0003] Chinese patent (CN 102434129 A) discloses an ultra-deep water offshore oil and gas engineering development system, which is used for oil and gas development in an ultra-deep sea environment with a water depth of more than 3000m. The system includes a surface floating production device, a standpipe support buoy, underwater oil production equipment, an upper flexible jumper, a lower rigid riser and...

AI Technical Summary

Problems solved by technology

Both mooring cables and rigid risers are passively tensioned by riser support buoys, so it is difficult to conveniently adjust the top tension of the two

Therefore, it is difficult for the above-mentioned riser support buoy to simultaneously provide the top tension force required by the mooring cables and the rigid riser;

[0007] 2. The burial depth of the riser support buoy must be large enough (below 200m water depth). If the burial depth is insufficient, the riser support buoy is susceptible to lateral deviation due to the influence of shallow water waves, which will cause mooring cables and rigid risers The secondary distribution of the top tension force causes the main stress change of the rigid riser, which is not conducive to the strength and fatigue performance of the rigid riser;

[0008] 3. The riser support buoy is moored on the seabed with three mooring cables. When any one of the cables breaks and fails for some reason, the riser support buoy changes from a three-point support to a two-point support, resulting in loss of stability. The top tension of the mooring rope and the rigid riser is redistributed, and the top tension of the rigid riser increases sharply, and the excessive top tension will break the rigid riser and cause the system to collapse

[0009] Due to the above problems, the riser support buoys in this system are difficult to apply in engineering practice

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