CN102815372A - Self-adaption type deepwater mooring system - Google Patents

Abstract

The invention discloses an adaptive deep-water mooring system, which includes a suspension buoy, a weight, a mooring buoy, an anchor, a pile foundation, an upper tension cable connecting the suspension buoy and the weight, a connection between the connection weight and the mooring buoy The self-adaptive deep-water mooring system has the advantages of high horizontal mooring stiffness, high vertical mooring stiffness, and cable tension The advantage of a more even distribution.

Description

An Adaptive Deepwater Mooring System

technical field

The invention relates to the field of mooring, in particular to a novel deep-water mooring system suitable for deep-water marine engineering structures.

Background technique

With the depletion of onshore oil and gas resources, the development trend of offshore oil and gas has shifted from offshore shallow water to far sea deep water. The deep-sea floating structure is the main equipment for the development of deep-water oil and gas resources. No matter what kind of floating structure is used, it needs a mooring system to moor it in a fixed sea area for a long time. The mooring system is an important guarantee for the normal operation and safety of floating structures, so it plays a pivotal role in deep sea development.

At present, there are two types of deep water mooring systems: catenary mooring system and tension mooring system. However, no matter which mooring system is used, there are common defects: 1. As the water depth increases, the horizontal stiffness of the mooring system decreases, which intensifies the movement of the floating structure in the plane (surge, sway, etc.) and yaw); 2. The vertical stiffness that can be provided is limited, which cannot well restrict the movement of the floating structure in the vertical plane (rolling, pitching and heaving); 3. The mooring cables alternately appear higher Frequency of relaxation - tension state, prone to fatigue fracture. The above defects have directly affected the normal operation and safety of the whole floating structure.

Therefore, it is particularly necessary to develop a new type of deep-water mooring system to solve the above problems.

Contents of the invention

In view of the problems and deficiencies in the prior art above, the purpose of the present invention is to provide an adaptive deep-water mooring system with high horizontal mooring rigidity, high vertical mooring rigidity and relatively uniform cable tension distribution.

In order to achieve the above purpose, the adaptive deep-water mooring system of the present invention can adopt the following technical solutions:

An adaptive deep-water mooring system, including suspension buoys, weights, mooring buoys, anchors, pile foundations, upper tension cables connecting suspension buoys and weights, connecting cables connecting weights and mooring buoys, and connecting Mooring buoys and lower tension cables for anchors, and tension tendons connecting mooring buoys and pile foundations.

Compared with the prior art, the present invention is as follows: after the self-adaptive deep-water mooring system of the present invention is connected with the mooring object, the weight acts as a catenary effect, and when the mooring object moves, the weight is pulled up to improve The stiffness of the adaptive deepwater mooring system is improved. The presence of suspended buoys and weights increases the resilience of the adaptive deepwater mooring system. The operating water depth of the suspension buoy, the upper tensioning cable and the weight is equivalent to H1 (the value of H1 needs to be determined based on the comprehensive economic performance and mooring performance. Generally, the operating water depth suitable for the tensioned mooring system is 500m-1500m) , which can be considered as an approximate "water depth truncation", but the same cable material and pretension are retained. Under the same cable material and pretension, the horizontal stiffness of the shallow water mooring system is greater than that of the deep water mooring system. Therefore, in the suspension The horizontal stiffness of the adaptive deep-water mooring system is greatly improved when the water depth of buoys, upper tension cables and heavy blocks is reduced. In addition, when the deep-water offshore platform has a large displacement, the lower tension cable will provide a large horizontal stiffness, and the tension tendon can also provide a large part of the horizontal stiffness after bending, so the horizontal stiffness of the total mooring system is further improved. improve. Due to the top pretension provided by the mooring buoys, the tendons are always in a tensioned state, and the axial stiffness of the tendons is extremely large, both of which greatly improve the vertical stiffness of the entire mooring system, and can The movement in the vertical plane of the deepwater ocean platform is limited to a very small range; therefore, after improving the horizontal stiffness and vertical stiffness of the mooring system, the present invention has the following advantages compared with the prior art: 1. Effectively reduce the The movement range of the offshore platform can improve the operating conditions of the deep-water offshore platform and increase the production capacity; 2. Effectively reduce the frequency of alternate tension-relaxation of the mooring cable, prolong the service life of the mooring cable, and reduce the risk of fatigue fracture of the mooring cable; 3. Cable tension distribution It is relatively uniform, and the mechanical properties of the cable material are fully exerted, which reduces the design and manufacturing costs of the cable; 4. Reduces the mooring radius and reduces the risk of collision with other submarine piping systems

Preferably, the buoyancy of the suspended buoy is equal to or less than the gravity of the weight, and the number of the suspended buoy is greater than or equal to one.

Preferably, the suspended buoy is a cylinder, a sphere or a polyhedron; the floating body of the suspended buoy is closed, or is provided with a water inlet and outlet switch or an air charging and discharging switch.

Preferably, the number of weights used is greater than or equal to one, and the gravity of the weights is greater than the vertical upward component of the initial pretension of the tension cables connected to the upper part of the buoy.

Preferably, the mooring buoy has mooring brackets, outrigger beams, water inlet holes and air inlet holes; the connecting cable is connected to the mooring brackets.

Preferably, the buoyancy of the mooring buoy can bear a part of the gravity of the weight while meeting the pretension requirements of the lower tension cable and the tension tendon.

Preferably, the upper tension cable and the lower tension cable are three-section cables used in traditional tension mooring systems, namely the upper end steel wire rope, the middle polyester cable, and the lower end steel wire rope.

Preferably, the number of weights is greater than or equal to one, and the gravity of the weights is greater than the vertical upward component of the initial pretension of the upper tension cable.

Preferably, the tension tendons are high-strength thick-walled steel pipes, and the number of tension tendons is greater than or equal to one.

Preferably, the tension cables and tendons are connected to outrigger beams connected to the buoys.

Description of drawings

Fig. 1 is a structural schematic diagram of an adaptive deep-water mooring system of the present invention applied to a deep-water ocean platform.

Fig. 2 is a schematic diagram of the mooring buoy in the self-adaptive deep-water mooring system of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, further illustrate the present invention, should understand that following specific embodiment is only for illustrating the present invention and is not intended to limit the scope of the present invention, after having read the present invention, those skilled in the art will understand the present invention Modifications in various equivalent forms fall within the scope defined by the appended claims of the present application.

Please combine Fig. 1 and Fig. 2 to show the specific implementation of the adaptive deep-water mooring system of the present invention applied to a deep-water ocean platform.

The self-adaptive deep-water mooring system of the present invention includes a suspension buoy 9 for connecting with a deep-water ocean platform 1, a weight 3, a mooring buoy 5, an anchor 8, a pile foundation 10, and a stretcher connecting the suspension buoy 9 and the weight 3 Tight cable 2, connecting cable 4 connecting weight 3 and mooring buoy 5, lower tension cable 6 connecting mooring buoy 5 and anchor 8, and tension tendon 7 connecting mooring buoy 5 and pile foundation 10.

As a mooring application example object, the semi-submersible platform 1 has an operating water depth of 1500m, and adopts the self-adaptive deep-water mooring system of the present invention as its mooring system. The mooring system uses 12 mooring cables connected to the buoy 5 at a water depth of 1000m. The total length of the upper tension cable 2 connected to the buoy is 1845m, and the materials are the first anchor chain 152m, the middle polyester cable 1522m and the lower end anchor chain 141m. The weight 3 is located at the bottom of the upper tension cable 2, that is, the rope length is 1845m. In order to increase the damping of the mooring system, in this embodiment, the number of the suspended buoys 9 is set to three, which are respectively located at 100m, 150m and 200m from the length of the fairlead, and the total buoyancy of the suspended buoys 9 should be less than The gravity of weight 3. The connecting cable 4 consists of a polyester cable and has a length of 100 m. The size of the mooring buoy 5 is determined by the pretension of the tendon 7 and the lower tension cable 6, and there are four outrigger beams 12 with a length of 8 m for connecting the tendon 7 and the lower tension cable 6. Considering the large heave response of the semi-submersible platform 1, in this embodiment, two tension tendons 7 are used with a length of 490m. At the same time, in order to better provide the horizontal stiffness of the adaptive deep-water mooring system, there are also two lower tension cables 6 . The material of the lower tension cable 6 is 152m of the first anchor chain, 600m of the middle polyester cable and 141m of the lower end anchor chain.

Its offshore installation follows the steps:

The position of the anchor point and the position of the pile foundation are determined by calculation, and the pile foundation 10 is laid to prepare for the insertion of the tendon 7;

Two anchors 8 in the mooring cable (in this embodiment, the anchors are suction anchors) are connected with two tension tendons 7 and two lower tension cables 6, and a mooring buoy 5 and its upper part Connect the cable 4 and the upper tension cable 2, and 3 suspension buoys 9 and 1 weight 5 complete set of equipment connected to the upper tension cable 2 are hoisted into the water;

The tension tendon 7 is inserted into the pile foundation 10, and the suction anchor 8 is driven into the seabed;

Mooring buoy 5 is filled with water to make its gravity and buoyancy reach balance;

Inflate the mooring buoy 5 and discharge the water. When the buoyancy of the connecting buoy 5 meets the pretension of the tension tendon 7 and the tension cable 6 at the lower part of the connecting buoy, stop inflating and the installation is completed.

After the self-adaptive deep-water mooring system of the present invention is connected with the mooring object, the weight 3 plays the role of the catenary effect. When the mooring object moves, the weight 3 is pulled up, which improves the self-adaptive deep-water mooring. the stiffness of the system. The presence of mooring buoys 9 and weights 3 increases the flexibility of the adaptive deepwater mooring system. The operating water depth of the mooring buoy 9, the upper tensioning cable 2 and the weight 3 is equivalent to H1 (the value of H1 depends on the comprehensive economic performance and mooring performance, and generally the operating water depth suitable for the operation of the tensioned mooring system is 500m -1500m), it can be considered as an approximate "water depth truncation", but the same cable material and pretension are retained. Under the same cable material and pretension, the horizontal stiffness of the shallow water mooring system is greater than that of the deep water mooring system, so , the horizontal stiffness of the self-adaptive deepwater mooring system is greatly improved when the mooring buoy 9, the upper tension cable 2 and the weight 3 operate at a reduced water depth. In addition, when the mooring object has a large displacement, the lower tension cable will provide a greater horizontal stiffness, and the tension tendon 7 can also provide a larger part of the horizontal stiffness after bending, so the horizontal stiffness of the total mooring system is further improved. improvement. Due to the top pretension provided by the connecting buoy, the tension tendon 7 is always in a tensioned state, and the axial stiffness of the tension tendon 7 is extremely large, both of which greatly improve the vertical stiffness of the entire mooring system. It can limit the movement of the deep-water offshore platform in the vertical plane to a very small range; after improving the horizontal stiffness and vertical stiffness of the mooring system, it can effectively reduce the movement range of the deep-water offshore platform, improve the operating conditions of the deep-water offshore platform, and increase the Production capacity; effectively reduce the frequency of alternate tension-relaxation of the mooring cable, prolong the service life of the mooring cable, and reduce the risk of fatigue fracture of the mooring cable; the tension distribution of the cable is more uniform, the mechanical properties of the cable material are fully exerted, and the design and manufacturing costs of the cable are reduced; 4 , Reduce the mooring radius and reduce the risk of collision with other submarine piping systems.

Claims (10)

1. a self-adapting type mooring system in deep water is characterized in that: comprise suspension floating drum (9), pouring weight (3), mooring buoy (5), anchor (8), pile foundation (10), the last tension cables (2) that connects suspension floating drum (9) and pouring weight (3), the connecting line (4) that connects pouring weight (3) and mooring buoy (5), connection mooring buoy (5) and the following tension cables (6) of anchor (8) and the tension force muscle tendon (7) that connects mooring buoy (5) and pile foundation (10).

2. self-adapting type mooring system in deep water as claimed in claim 1 is characterized in that: the buoyancy of suspension floating drum (9) is equal to or less than the gravity of pouring weight (3), and the quantity of suspension floating drum (9) is more than or equal to one.

3. according to claim 1 or claim 2 self-adapting type mooring system in deep water, it is characterized in that: suspension floating drum (9) is cylinder or spheroid or polyhedron; The buoyancy aid of suspension floating drum (9) is closed, or is provided with the Inlet and outlet water switch or charges and discharge air cock.

4. self-adapting type mooring system in deep water as claimed in claim 3 is characterized in that: used pouring weight (3) quantity is more than or equal to one, and pouring weight (3) gravity is gone up the component vertically upward of the initial pretension of tension cables (2) greater than connecting floating drum (5).

5. self-adapting type mooring system in deep water as claimed in claim 4 is characterized in that: have mooring support (15), overhanging beam (12), inlet opening (13) and induction opening (14) on the said mooring buoy (5); Connecting line is connected on the mooring support (15).

6. self-adapting type mooring system in deep water as claimed in claim 5 is characterized in that: the buoyancy of mooring buoy (5) can be born the gravity of a part of pouring weight (3) when the pretension that can satisfy following tension cables (6) and tension force muscle tendon (7) requires.

7. self-adapting type mooring system in deep water as claimed in claim 6 is characterized in that: three sections cables that tension cables (6) was used for traditional tension type mooring system under upward tension cables (2) reached, i.e. upper end steel rope, middle polyester cable, lower end steel rope.

8. self-adapting type mooring system in deep water as claimed in claim 6 is characterized in that: pouring weight (3) quantity is more than or equal to one, and pouring weight (3) gravity is greater than the component vertically upward of the initial pretension of last tension cables (2).

9. self-adapting type mooring system in deep water as claimed in claim 8 is characterized in that: tension force muscle tendon (7) is high-intensity thick walled steel tube, and tension force muscle tendon (7) quantity is more than or equal to one.

10. self-adapting type mooring system in deep water as claimed in claim 9 is characterized in that: tension cables (6) and tension force muscle tendon (7) are connected on the overhanging beam (12) of mooring buoy (5).

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