Riser self-tensioning type underwater production support buoy and mounting and recycling method thereof

Abstract

The invention discloses a riser self-tensioning type underwater production support buoy and a mounting and recycling method thereof. The riser self-tensioning type underwater production support buoy comprises an outer layer buoy and inner layer buoys, wherein the plurality of inner layer buoys are embedded in the outer layer buoy. As the outer layer buoy is in charge of providing a tensioning force of a mooring cable and the inner layer buoys provide top tensioning forces of rigid risers, the riser self-tensioning type underwater production support buoy can conveniently provide desired top tensioning forces of the rigid risers and the mooring cable at the same time; and requirements of practical engineering application can be only satisfied by using the riser self-tensioning type underwater production support buoy in a super deep water ocean oil and gas engineering development system. As vertical motions and stresses of the rigid risers and the outer layer buoy are decoupled, the stress and motion amplitudes of the rigid risers can be reduced to be the benefit of improving the strengths and fatigue performances of the rigid risers. When the buoy is biased, secondary distribution of the top tensioning forces among the rigid risers can be avoided to be the benefit of improving the strengths and fatigue performances of the rigid risers so that the rigid risers satisfy use requirements.

Description

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

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 provide the top tension required by the mooring lines and the rigid riser at the same time

[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 resistance 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 three-point support to 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 the above systems are difficult to apply in engineering practice

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