FR2853673A1 - Flexible column recovering gases, liquids, viscous substances or solids from marine depths, is sectional with support blocks at intervals, joined by ropes for tension relief - Google Patents

Abstract

The tough, flexible, large-diameter column descends several thousand meters to the depths, being suspended at the surface or a stable sub-marine location. Its sections (B) are two hundred meters long and supported by rigid blocks held on ropes (T1-T4) between them. At the lower end a capture skirt (J) is anchored (Z) on the sea bed, to collect buoyant materials arising there. The column and skirt are made from a flexible film. This perforated locally, when used to recover viscous or solid material, to allow for displacement, assisting the ascent of hydrocarbons or other buoyant materials. Fiber reinforcement of the film resists tearing, despite the constraints. Further semi-rigid reinforcement is used. The rigid blocks resist high pressures. They keep the column sections under tension, whilst most of the weight is transferred onto ropes (T). Rigid circumferential rings (O1-O4) with an anchoring system, reinforce the collection skirt. A thick, buoyant foam coating on the blocks, relieves some of their weight. The system is supported on e.g. a surface structure, stable sub-marine installation, or a floating vessel with a buoyant barrier.

Description

1 1

  The present invention relates to a flexible column device under tension suitable for cables allowing vertical deployment of a length of several thousand meters in the marine environment. This device is designed with the aim of recovering towards the surface gaseous, liquid, viscous or solid materials emanating from the seabed and rising by themselves, released for example from a sunken ship or from a poorly sealed drilling well. 10 For flexible columns with large diameters, the ordinarily possible lengths depend on the tear resistance of the materials used, and on their capacity to remain in their initial shape whatever the external elements (winds, currents, pressures, temperature differences).

  In fact, whatever the materials used, the Strength / Weight ratio very quickly limits the possible length in the vertical position.

  In order to maintain the initial characteristics of a flexible column while allowing very long lengths, the present invention relates to a device making it possible to remedy these problems (resistance and behavior of the materials used) by a combination of minimum mass and controlled tension. giving a relative rigidity to the assembly, with no other length limit than the resistance of the cables used.

  The method used for the transfer of loads is such as to allow a column 25 as long as the resistance of these cables allows.

  The invention proposes a flexible column of elements of fixed length assembled together by rigid elements (chairs) and terminated by a cone (upe) allowing the collection at the source of the materials to be recovered. The assembly is kept in tension from a point 30 located at (or below) the surface by cables passing through the chairs.

  Embodiments of the invention will be described below, by way of non-limiting examples, with reference to the accompanying drawings.

  1 This device consists of: a) a column of fine and flexible material from the plastics and petroleum derivatives industry (example polyethylene film) in the form of a tube (B) with a diameter of one meter and in sections 200 meters (Bl to Bn).

  Over their entire length, these sections (Bi to Bn) are gridded with a reinforcement of nylon fibers embedded in the material and arranged so as to increase the resistance in the direction of the length.

  The ends of these flexible sections are of reinforced thickness over a length of 1.5 meters (M) so as to withstand clamping by a collar (E) without being damaged.

  These flexible column sections (B1 to Bn) have in their middle and fifty meters 15 on either side, three semi-rigid rings (RI, R2, R3) glued or included in the film material, without however presenting roughness on the inner face of said column.

  In the case of the recovery of viscous products, each of these flexible sections of 200 meters (BI to Bn) comprise, over 20 meters of their lower part and over the entire surface 20 (P), circular holes of 5 millimeters in diameter and for a density of 500 holes per m2.

  In the case of gaseous products, the flexible films are not perforated.

  b) elements of hard and high density material (for example PVC) called "chairs" (C) and comprising three parts: - A rigid PVC tube (A) with a length of 4 meters and a diameter of 1 meter, provided with notches at its two ends to ensure the clamping of flexible sections 30 (B), glued (chemical welding) in the middle inside a block of (h) 2m x 1 , 4m x 1.4m.

  - a block of PVC (U) of h: 2m x 1.4m x 1.4m made in two half shells (Ul, U2) of solid material.

  At each of its angles, this block (U) is perforated in its height with a channel with a diameter slightly greater than the diameter of the tension cables (Tl to T4), and equipped on each edge with a self-locking clamping system (X).

  1 This block, once assembled around the rigid tube, is surrounded by a shell of syntactic foam (W).

  - a shell of syntactic foam (W) nested on the outside of the PVC block (U) so as to increase the buoyancy index of the chair.

  These chairs (C) receive on their high and low rigid tubular parts the flexible threaded sections (B) and tightened by collar (E).

  c) four cables (for example steel or nylon) (Tl to T4) adjusted and tightened inside each of these chairs (C) and thus transferring the overall load to the top of the column, without the flexible part (B) participate. These cables are calculated to support an overall load in the marine environment representing the mass of the column thus formed.

  These cables are provided with an anchor (Z) set in the body of the first chair (C) (low chair), and go up through all the others to a general tension system, located either on the surface (ship , structure on buoy, offshore platform), or on an underwater station.

  The cable tightening system on the cubic body of each chair (C) is made up of two principles: a principle of tightening by nut or key (S) and a self-locking principle (X).

  Principle of tightening by nut or key (S) The two PVC half shells (UI and U2) are perforated over their entire height, in each angle, with a channel of sufficient diameter to allow a cable to slide (Tl, T2, T3 30 or T4).

  On each edge and located halfway up the cubic body of the chair, notches equipped with cable tightening devices by nut are arranged so as to allow the lengths between chairs to be adjusted.

  These lengths correspond to the flexible sections described above (B).

  The adjustment is made at sea during installation, section after section over the total length necessary for the recovery operation.

  1 Self-locking principle (X) The channel in its lower part is finished on thirty centimeters by a conical shape allowing to introduce a steel cone in two parts and whose internal concave faces are grooved.

  This cone which is housed in the conical part of the channel, on either side of the cable, clamps all the more the latter as it tends to slide upwards in the event of insufficient tightening.

  Plugs perforated in their center and not closed, introduced by pinching and allowing the cables to slide, close this conical part of the channel after the jaw.

  d) a funnel-shaped "skirt" (J) made of the same flexible film reinforced with nylon, located at the base of the column and with a diameter of 15 meters at its base and 1 meter at its top, terminated in the upper part by a flexible tubular section (1) with a diameter of 15 meters and a length of 1 meter threaded on the rigid tube (A) bottom of the first chair (C).

  This skirt is encircled by four circular frames (01 to 04) of solid non-deformable material capable of maintaining the shape of the cone and connected together by ropes (F) anchored 20 in the lower part of the block (A) of the first chair, so as to allow deployment of the skirt by transferring its weight to said chair.

  These reinforcements (01 to 04) can be made of the same material and made integrally with the skirt (J), or else be added to the outside of the latter. 25 In the case of the recovery of viscous or solid materials, the flexible part of the skirt is perforated with holes (P ') with a diameter of 5 millimeters over its entire circumference and along wide horizontal bands between the straps (01 to 04), according to a density of 500 holes per m2.

  In the case of recovery of gaseous or liquid materials, no drilling of the flexible part will be carried out.

  The plunge descent operation will then be "folded skirt", frames (01 to 04) in a vertical position.

  The larger diameter frame (04), located at the base of the device, is fitted with anchoring systems (Z) either for fixed anchors or to receive horizontal guide cables anchored to the bottom.

  1 The assembly thus constitutes a taut and flexible column whose flexible lengths do not participate in the load transfer.

  Only the chairs (C), locked in fixed positions and crossed by the tension cables (Tl to T4), transmit to these cables the single load of more or less 200 meters of flexible column (B).

  The submerged assembly is therefore supported every 200 meters by rigid elements (C) transferring all the forces on the stretched cables (Tl to T4) from the surface or underwater installation.

  The column is in the lower part terminated by a skirt (J) the wide part of which is close to the source to be captured, so as to channel the recovery of materials lighter than water up to said installation.

  The accompanying drawings illustrate the invention: * Figure 1 shows the principle of the column as a whole without defining the choice of the supporting structure, which may, depending on the case, be a stable underwater structure, a surface vessel or even a system autonomous surface comprising a floating structure and a recovery zone by floating dam * Figure 2 shows the lower part of the column or skirt (J).

  * Figure 3 shows the detail of a chair (C), the passage and blocking of cables (Tl to 25 T4), the junction of the flexible parts of the column (B) on the chairs (C).

  ò Figure 4 shows the low chair and its junction with the skirt (J), one of the two half shells (Ul or U2) forming the chair block once glued to the rigid tube (A), the cable passage channels (D), the mantle of syntactic foam (W). 30

Claims (9)

1 CLAIMS   1) Device constituting a column of flexible, resistant material of large diameter (A) intended for immersion in the marine environment over a length of several thousand meters and 5 suspended from the surface or from a stable underwater position, manufactured in sections of a single piece of two hundred meters (B1 to Bn), supported at equal distance by rigid blocks or chairs (C) held together by tension cables (T1 to T4) carrying the loads, and partly completed low by a catching skirt (J) anchored (Z) to the seabed in order to collect products lighter than the water emanating from these funds.   2) Device according to claim 1, characterized in that the flexible film, constituting the column (B) and the skirt (J), is perforated on part of its surfaces in the case of the recovery of viscous or solid products, 15 to allow its movement in the seabed, and maintain over long lengths the upward dynamics of hydrocarbons or products of density less than 1 inside said device.   3) Device according to claims 1 and 2,   characterized in that the film of flexible material (B) is reinforced or reinforced by a mesh of nylon fibers, glued or embedded in the thickness of the film allowing, despite the lengths used and the external constraints to resist tearing.   4) Device according to claim 1 characterized in that the sections of more or less 200 meters made of flexible material film are reinforced in the middle and on either side every 50 meters of semi rigid rings (R1 to R3 ), either in simultaneous manufacture and of the same material, or glued, so as to guarantee its shape and its diameter over its entire length.   5) Device according to claim 1, characterized in that the blocks of rigid material or chairs (C) capable of withstanding high pressures allow the continuity of the column while keeping taut the flexible parts (B) whose load is transferred on the cables (T).   6) Device according to claim 1, characterized in that the flexible column base consisting of a cone-shaped skirt or funnel (J) of flexible material and non-deformable circular frames (01 to 04) (including dimensions, determined according to the planned operation are equipped with 1 anchoring systems (Z) allowing both stability as well as mobility in deep waters), is capable of collecting fumes under gaseous, liquid, viscous or solid rising to the surface.   7) Device according to claims 1 and 5   characterized in that the principle of construction of the flexible column, stretched from block to block, transfers the loads onto the cables and makes it possible to reach very long lengths without requesting the resistance of the materials which compose it.   8) Device according to claims 1 and 5   characterized in that the rigid chairs (C) are sheathed on their cubic part with a thick mantle of syntactic foam (W) calculated to decrease in the best proportions the mass value of said chairs (C) once immersed and increase by the same amount their buoyancy and therefore reduce the load carried over. 15 9) Device according to claim 1 characterized in that different solutions are adaptable as regards the suspension system of the assembly: - Suspension and tension of the cables from a surface vessel, - suspension and tension of the cables from a stable underwater installation, - suspension and tension of cables from a floating structure with floating barrier.