MXPA99011759A - Hybrid riser or pipe with flexible and rigid sections for fluid transfer - Google Patents

Abstract

A deep water pipe for transferring a fluid between a floating support (1) and a point below and along the surface, has a flexible part (7) connected at one end to the underwater point and a rigid part (6) connected at one end to the flexible part and at the other to the floating support by a holder (9) allowing it to be put under tension by its own weight Preferred Features:The flexible part is defined by establishing the extreme movements of the floating support, supposing that the movements of the top of the flexible part are identical to those of the floating support, and choosing a position (Ph) for the top end of the flexible part in the vertical and dimensioning the flexible part to take at least the predetermined movements taking into account the following parameters:the internal pressure (Pint), the external pressure (Pext), the type of fluid, maximum forces such as maximum traction (Tmax) seen by the flexible part, and the value of the maximum allowable curvature (courbmax). If the flexible part cannot achieve the conditions of use, the position Ph is changed. The rigid part is defined for given means of holding and a diameter (Dr). Its length (Lr) is chosen to be equal to the distance in equilibrium conditions between the top of the flexible riser and the means of holding. Its thickness (er) is defined to fit the constraints of:the weight of the pipe, the hydrodynamic forces, And forces induced by movement of the floating support and internal and external pressures. The rigid part of the riser inside or next to the floating support is checked to ensure it does not come into contact with the floating support. The stages of dimensioning the two parts of the riser are done under static conditions or under dynamic conditions. Means of thermal insulation are includes on at least the rigid and/or flexible parts.

Description

ELEVATOR OR HYBRID COLUMN FOR FLUID TRANSFER Description of the invention The present invention relates to a lifting column or vertical production pipe or upright column that includes a flexible part in its lower part in connection with one or more sources of effluents and a rigid part in its upper part. The invention is particularly adapted for production systems for oil effluents, mainly for the production of oil and gas using a floating support anchored to the seabed, which is in connection with one or several production wells through one or several riser ducts or production ascending column composed of at least one rigid part at the top, and a flexible part at the level of the seabed. The ducts can be independent or connected to each other in the form of turns of ascending columns. The invention also relates more generally to any conduit that permits the transfer or transport of a fluid from a REF .: 32296 site to another site, for example the lines of fluid injection (water, gas ...). Production systems are usually installed for relatively long durations, for example 20 years. During the entire duration of their installation and in the course of production operations, they are subject to external constraints, such as storm surges, current, wind, etc. Usually the floating support is statically anchored to the seabed by a set of vertical or oblique lines or lines. In both cases, it retains a certain freedom of movement in and according to different axes, ranging from a few centimeters to several meters for vertical displacements due to the tide, known in this domain under the term of tamping and that can go up to tens of meters in the horizontal plane, known under the terms of shift, lurch and slow drift. The rotations around the horizontal axes, roll / pitch, and around the vertical axis, embazadura, depend on the dimensions of the floating support, its anchoring means, and the conditions of the tide, current and wind. Classically, in such installations, the upright columns are fixed on the one hand to an underwater structure placed on the bottom and that generally assemble several well heads, on the other hand, these are in direct or indirect connection with a floating structure by appropriate devices . These connection devices make the riser conduits more or less integral with the floating support and therefore its displacements. The use of ascending or flexible columns is particularly adapted to this type of movement. These respond very well to the movements in the head or upper part (at the level of the union with the floating support) and the contact to the ground is well mastered. The numerous applications of flexible ascending columns distributed throughout the world and in the domain of offshore platforms show that the fatigue aspects for this type of ascending column can be considered sufficiently dominated. The adjustment to the appropriate dimensions of the flexible riser columns "must take into account the traction and collapse, among other criteria.In deep seas, and knowing that a flexible is generally heavier than a rigid, the combination of the two criteria The above-mentioned columns can become difficult to control: for the completely rigid and practically vertical ascending columns, and in order to make these displacements tolerable by the column upright, the suspension systems, better known under the term tension systems (tensioning), are generally put into operation. For example, hydraulic tensioning systems or passive tensioning by floats are used, which keep the column upright under a slightly more constant tension and independent of the movements of the support. These systems can become very problematic for the deep upward columns. The systems of rigid ascending columns called catenaries, which can be considered in deep seas, use the flexibility of the metal over a large length of the ascending column in order to give it a shape similar to those, classic, flexible. These ascending columns may optionally be provided with tensioning means but present two important drawbacks: • a large horizontal distance between the head of the ascending column and the -head of the submarine well, • fatigue of the point of detachment is critical. The prior art also describes different arrangements designed primarily to pick up or pick up the movements of the floating supports, joining the rigid part and the flexible part for the ascending column system. For example, hybrid ascending columns such as those used in US Pat. No. 4,661,016 or the Compliant Mobil / IFP ascending column presented for example in 'Applications of Subsea Systems' (Goodfello Associates Ltd, 1990) are composed of a rising column or a series of rigid ascending columns extending to the bottom of the ocean, up to a certain given depth.This depth is preferably below the turbulence level of the tide, where they are stressed by a buoy underneath The upper end is connected to the flexible risers that allow the transport of fluids to a floating support.These last columns are the ones that collect the differential movements between the support of the buoy - There are other versions of this configuration where the rigid ascending columns are catenary ascending columns such as that those described in US Pat. No. 5,639,187. The idea of the present invention is to conceive a conduit for large depths of water, which allow to transfer a fluid, putting the conduit in connection with a floating support and the sea floor, for example or even a point placed at an important depth below the support Floating The duct mainly has as a feature, the inclusion of at least one flexible part in connection with the sea floor and at least one rigid part in connection with the floating support, the two parts being joined, namely the rigid and the flexible part. The length of the rigid part is at least equal to the distance separating a point located on the sea floor and a point on the surface of the water. This distance is designated in the subsequent description by the expression "water depth" or * water bed "D. The rigid part is for example in connection with the floating support by adapted means that allow the conduit to be put under tension mainly by the weight of the system as a whole, namely the assembly of the ascending column and the rigid part that carries a fluid, over a greater part of the water depth D. The conduit can be, for example, a rising column of production. the subsequent description is understood under the expression 'its own weight': * the weight of the conduit or the ascending column composed of the different rigid and flexible parts that constitute it, or even * the weight of the set of these two parts and of the equipment associated with the duct or the rising column, such as the insulation elements, the elements of connection or connection between the different parts, or even any other element that completes the conduit or the ascending column. A rising column of this type is very well suited to seas of depths greater than 500 m and more particularly greater than 1000 m and to ultra-large depths. The invention also relates to a conduit for large depths of water, which allows the transfer of a fluid between a floating support and a point located below, and at a distance away from the surface of the water. This is characterized because it includes: = > at least one flexible part in connection at one of its ends with the point located below the surface, y = > at least one rigid part in connection with the flexible part at one of its ends and at the second end with the floating support. = the length of said rigid part is at least equal to half the depth of water D. According to a variant embodiment of the conduit, = >; the flexible part is defined for example in the following way: a) the extreme movements of the floating support are established, b) it is assumed that the movements of the height of the flexible part are substantially identical to the extreme movements, c) the Ph position of the upper end of this flexible part in the vertical, so that this length of the rigid part represents a greater part of the water depth, and are the appropriate dimensions of the flexible part in order to take at least the preset movements taking into account at least the following parameters: the internal pressure Pint, the external pressure Pext, the nature of the fluid, the maximum stresses such as the maximum tensile Tmax observed by the flexible part, the value of the maximum admissible curvature courbmax, d ) if the flexible part does not respect the conditions of use, at least the position Ph, = > the rigid part is defined for the given maintenance means and a diameter value Dr, e) its length Lr is chosen to be substantially equal to the value of the distance under the equilibrium conditions existing between the upper end of the flexible rising column and the means of maintenance, the value of its thickness is defined and in order to take or collect the constraints generated by at least: the weight of the duct, the weight of the suspended part of the flexible part, the hydrodynamic stresses, the stresses induced by the displacements of the floating support, the internal and external pressures, f) it is verified that the rigid part of the ascending column that is placed inside or on the edges of the floating support does not come into contact with a part of the floating support, and eventually returns to stage b). For example, the sizing steps of the flexible part and the rigid part are carried out under static conditions and the sizing can be verified under static conditions by the sizing steps under dynamic conditions. According to another embodiment variant, the sizing steps of the flexible part and the rigid part are carried out under the dynamic conditions. The conduit may include the thermal insulation means placed on at least the rigid part and / or the flexible part. The rigid part of the column is, for example, maintained in the floating support with the aid of the maintenance means which allow the conduit to be tensioned under its own weight. The invention also relates to an ascending column or production column for the transfer of effluents from a production well to a support that includes for example at least one of the characteristics indicated above of the conduit, for large depths of water that it allows the transfer of a fluid between a floating support and a point located below, and at a distance away from the surface of the water. The conduit according to the invention can also be an injection line where the rigid part is in connection with a source of fluid to be injected, and the flexible part is in connection with a site where the fluid must be injected. The invention also relates to a system for the production of oil effluents of great depths of water, which allows the transfer of a fluid between a floating support and a source of effluents, characterized in that it includes at least one or more ascending columns and / or one or more injection lines having at least one of the aforementioned characteristics for driving for large depths of water that allow the transfer of a fluid between a floating support and a point located below and at a distance away from the surface of the water . The system can include at least one catenary anchoring system applied on the rigid riser at the level of the joint and / or the connector between the flexible part and the rigid part. The system includes, for example, supplementary means for energizing the ascending column (s). With respect to prior art devices, an ascending column according to the invention has mainly the following advantages: 0 the use of systems or tensioning means (such as a sub-surface buoy) in normal operation, ie during production operations, is not needed, and the rigid part is not connected to the support except at its upper end, contrary to the classic hybrids. 0 the weight of the flexible part is generally larger than that of the rigid part, the flexible and rigid parts arrangement according to the invention allows mainly to limit the tension in the upper part and therefore extend the domain of the use of the flexible part in deeper seas, or use well-established properties of the flexible parts to solve the problems of fatigue at the level of the point of detachment and the rigid parts to solve the problem of weight in very deep seas, or as a rule , the rigid part of the ascending column will be longer than the flexible part, and the thermal insulation on the first part will be easier to make, or it is not necessary to oversize the floating support as in the case of vertical rigid riser columns, laid by hydraulic tensioners. The latter require the use of tensioning systems that take into account the safety coefficients that lead to the oversizing of the floating support, or all the upper horizontal distances of the floating wells / support are taken into consideration, in a manner contrary to vertical rigid riser columns. or catenaries.

Other characteristics and advantages of the present invention will emerge better from reading the following description, made in an illustrative and non-limiting manner, with reference to the attached drawings in which: • Figures 1A and IB schematize two variants of the production system that they include a hybrid rising column according to the invention having respectively a flexible part in the form of a) 'folding wave "and of b)" loose wave ". • Figures 2 to 5 outline different maintenance devices, • Figure 2 represents the simplest maintenance device where the riser must be threaded and the flange bolted, • Figure 3 represents a maintenance device where the maintenance clamp can be opened and where the flange is screwed, • Figure 4 represents a maintenance device where the maintenance clamp opens and has a groove, thus allowing an axial rotation, • Figures 5A and 5B represent two variants of embodiment for the maintenance device comprising two clamps that can be opened, enclosing a) one or b) two collars; and • figure 6 schematizes a production system that includes several ascending columns. Figures 1A and IB show two examples of production systems put in an illustrative manner and In no way limiting, to highlight the particularities of the placement of the different elements that constitute it. These two figures differ mainly by the shape that can be taken for the flexible part of the hybrid rising column according to the invention, which can be for Figure 1A of the type "Folding Wave" and for Figure IB of the type "Loose Wave" " Some elements common to the two figures have the same references. The production system includes, for example, a floating support 1 anchored to the seabed 2 with the help of anchoring means 3, such as a set of chains or lines laid, for example, of anchoring lines. The support is placed, for example, in the vicinity of one or more sources 4 of oil effluents, for example one or more production wells. An ascending column 5 which makes it possible to trace the effluents from the source towards the floating support, is composed for example of a rigid upper part 6 and a flexible lower part 7, connected to each other for example with the aid of a connector 8. The part upper or end 6B of the rigid part of the ascending column is fixed to the floating support 1 by a maintenance device 9 that allows the tensioning of the rigid part of this ascending column, mainly under the effect of the weight of the whole of the ascending column. In the course of normal operation, anchoring or maintaining the rigid part at the level of the floating support does not require the tensioning system such as a sub-surface buoy usually used in the prior art between a riser and the floating support, or in the upper part of the rigid part of the ascending column.

The lower part 6A of the rigid part and the upper part 7B of the flexible part are both connected to the connector. This connector is located in such a way that the length Lr of the rigid part is at least equal to half the depth of the water. The flexible lower part is connected at its end 7A for example to the production well by devices commonly used in the field of oil production, and which will not be detailed as they are well known. This can also be in connection with the production wells with the help of flow lines. Without going outside the scope of the invention, it is possible to arrange, for example at the level of the union of the rigid part and the flexible part, of an element that allows the tensioning of the ascending column, when the weight of the latter is not Enough for herself. In order to limit the horizontal movements of the lower part of the rigid part, one or several anchoring lines 10 can be used and connected, for example, to the level of the part of the rigid ascending column, slightly above the connector 8. The sizing of these anchoring lines will be made according to the foreseeable movements of the floating support. The lateral movement of the ascending column can be limited, for example, to the foreseeable extreme maximum excursion of the floating support. A constraint limiter 11 is optionally added below the maintenance device 9, therefore at the level of the floating support. This allows mainly to minimize the effects of curvature and constraints considered by the ascending column under the effect of tidal movements, hydrodynamic forces and other external elements. This is adapted over at least a part of its length to withstand at least the constraints induced by the stresses transmitted by the marine environment, those induced by the maintenance device and the constraints due to the weight of the loads supported by the limiter. This constraint limiter can be, for example, conical in shape or made up of several cylindrical sections of varying thicknesses. This is preferably positioned just above the lower fixing of the riser column to the floating support, therefore on the rigid part.

The constraint limiter may form an integral part of the rigid part of the ascending column or may be an envelope of the latter. The shape of the flexible riser can be one of the classic shapes of the flexible riser columns such as for example "free hanging", * S loose "," loose wave "," S steep "," steep wave ", or" folding wave. "In this way the known properties of the flexible part can be used to dimension this flexible part, in particular for fatigue resistance.The rising column according to the invention is defined for example by at least the following parameters : • a flexible part of length Lf, of thickness ef, of diameter Df, • a rigid part of length Lr, of thickness er, of diameter Dr, and • the length Lr of the rigid part is at least equal to half of the water depth "D" (distance between the floating support 1 and the seabed 2) The diameters considered can be the internal or external diameters of the different parts.

The nature of the materials forming the rigid part and the flexible part of the rising column will, for example, be chosen as a function of the fluid transported towards the inside of the rising column. These will be for example resistant to H2S, or even to any other component or products liable to damage the flexible part on its flexible part or its rigid part. The dimensioning of the ascending column or the ascending column system can be carried out in several stages and taking into account the known parameters, for example in the following manner, considering a dimensioning in a static form, by way of illustration and in no way limiting. For example, extreme quasi-static conditions (where the inertial effects are negligible) are chosen, these conditions being possible by a combination of maximum roll or pitch angle values or even by the values of infrequent currents, such as the centennial currents, associated to the displacement values of the extreme floating support, in accidental case, for example a broken mooring line.

The displacement values can be marked by a displacement angle taken relative to a given axis, or even in relation to a floating support point, for example the displacement angle from, for example, a vertical axis is considered, and the amin and amax values. These can also be chosen as is a percentage of the depth as it is imposed by certain standards. It is thus possible to take into account the vertical movement of the floating support.

Sizing steps in statics for example a) the horizontal and vertical extreme excursions of the floating support that will be established at the beginning (displacement values of the extreme floating support), amin and amax, b) the hypothesis that the height of the flexible part of the ascending column is formulated for example will follow the pre-established excursions as much as possible, c) size the flexible part of the ascending column using the sizing methods known to those skilled in the art to collect these preset movements and taking into account at least the following data = > the vertical position of the upper end of the flexible part is chosen, point Ph, in such a way that the length of the rigid part suspended is at least equal to half the depth of water D, but that it can be equal to 9 / 10 of the water depth or more according to the depths considered = > a form is given for the flexible part, mainly depending on the system in which it is used (number of ascending columns, placement of some in relation to the others, number and position of wells), = > of the internal pressure Pint resulting from the circulation of the circulating fluid in the ascending column, and of the imposed pressures, = >; of the external pressure Pext exerted by the environment on the ascending column and which is mainly a function of the water depth considered, == of the maximum traction Tmax considered, the flexible part suffering a traction mainly due to its own weight, and of the Extremely vertical extreme excursion, = > the maximum curvatures so as not to exceed, over the length of the flexible part, a limit value courbmax is given which must not be exceeded, depending on the composition of the flexible part, = > optionally of the maximum torque considered, = it is verified that the flexible part respects the conditions of use, and if not, at least one of the two parameters is changed, the position in the vertical of the upper end of the flexible part or the shape of the the flexible part, d) choose a maintenance device that equips the floating support, = > this may be of the ball-and-socket type such as a flexible joint = > or even a fixing and maintenance device such as those described in figures 2 to 5, for example e) dimensioning the rigid part = the diameter Dr of the rigid part is given according to the needs of the users, = > the length Lr is chosen substantially equal to the value of the distance between the upper end of the flexible rising column and the maintenance device that equips the floating support, considering the system in equilibrium, this value represents a greater part of the water depth as defined in step c), = > the thickness er of this part is defined to be able to take at least all the constraints generated by: the weight of the ascending column, the effort exerted by the flexible part at the level of the connector that forms the union between the two parts or at the level of the same union, the hydrodynamic efforts exerted by the environment (waves, current, ...) the forces induced by the displacements of the floating support, the internal and external pressures defined above and that are exerted on the two parts of the ascending column, the Susceptible twisting, etc. and the type of maintenance device used at the level of the floating support. The calculations that allow determining the thickness resort to classical methods and known to the person skilled in the art, f) it is verified that the rigid part of the ascending column that is placed inside the floating support does not come into contact with a part from the last batch. Otherwise, either the type of maintenance device or the position of the anchor point of the rigid part of the ascending column to the floating support are changed, and the steps are repeated, for example, from step b). It will be ensured that the flexible riser is adapted, for example, its resistance to bending, for the given storage conditions or the laying conditions. When the riser is provided with a constraint limiter 11 placed at the level of the rigid part and the floating support for example according to an arrangement described in figure IB. This limiter is dimensioned so, for example, in order to preserve a constant curvature at this joint, the value of the curvature must be less than the maximum curvature acceptable for the rigid part of the ascending column. Flexion constraints and / or Von Mises constraints must respect the rules in force in the domain where the ascending column is used. Steps a) to f) are for example carried out in static calculation, taking the cases of the most unfavorable configurations previously indicated, such as for example: the roll angle or maximum pitch in the upper part or head, associated with a current centenal in the countercurrent direction to the trend of this angle.

Stages of verification in dynamics of dimensioning of the ascending column made in static conditions After having dimensioned the ascending column, the static conditions and putting the previous stages into operation, a dynamic analysis of the verification of the sizing of the ascending column is carried out according to the regulations in force. It will be verified mainly that under the dynamic effects of the tamping, not necessarily taken into account in the stages of dimensioning in statics, the maximum traction is acceptable. If the excursions of the point of union of the flexible and rigid parts are lower than those mentioned above but the dynamic effects are important and the rules are not respected mainly in constraints and fatigue, then the ascending column is dimensioned again taking the stage c) and in dynamics. The analysis in dynamics can be carried out in relation to the behavior of the point of union of the two parts, namely flexible and rigid, of the fixation in the upper part of the rigid part or even of the two. For example, if the dynamic analysis shows that the lower part of the rigid part of the ascending column corresponding to the junction of the two parts has an excursion superior to that of the floating support, at least three cases can be considered: Case 1 The excursion of the junction point of the two parts corresponding to the lower part of the rigid part, is acceptable from the point of view of the sizing criteria of the rigid part and the flexible part, and the sizing is not modified.

Case 2 The excursion is not acceptable, a first variant consists of adding the anchor lines limiting the movements that are placed between the level of the connector or the union of the flexible part and the rigid part, and the floor. The lengths of the anchoring lines are, for example, calculated so that, when extended, the excursion of the connector is limited relative to that of the floating support, and is only slightly greater. The stress induced in these lines is calculated immediately in order to correctly dimension the anchor lines. It will be ensured immediately that there is never interference between the ascending column and the anchoring lines.

Case 3 When the anchoring lines can not be used, and when certain criteria of the conditions of use of the flexible part are no longer respected (for example, a very important curvature), the sizing of the flexible part in stage b) is taken up taking into account for the excursion parameters the values more important than those of the floating support (excursion values given initially). In general, for example, the length L r of the rigid part of the rising column is chosen so that its lower end 6 A is well below the lowest level of the floating support. D being the depth of the water taken at the level of the floating support, where H is the height of the floating support, where Hf is the height relative to the sea floor of the upper end 7B of the flexible part, the value Lr is greater than H, and the ratio Lr / Hf is preferably greater than 3 for depths greater than 1500 m and the Lr / D ratio is, for example, greater than 0.5 and can go up to 0.95 or more according to the depth and environmental conditions and movements in the top Figure 2 represents a first anchoring mode of the upper part of the ascending column 6 at the level of the floating support 1. For this, the floating support is equipped with a maintenance means that includes a plate 20 integral, for example, with the floating support provided of a part 21 substantially perpendicular to the plate 20. The part 21 is provided with a passage hole 22 for the ascending column or the constraint limiter and for different fixing means, here the holes 23a that allow to fix the screws or any other fixing means. The upper part of the ascending column or of the constraining limiter is equipped with a flange 24 or ring that is provided with holes intended to receive the means 23b for fixing the flange on the integral part of the floating support. Advantageously, the plate 21 may include a constraint limiter attached, for example, to its lower face. The height of the part 21 can be more or less important, according to the efforts that it will be necessary to collect. Figure 3 shows another variant embodiment for the ascending column maintenance device. The part 21 of figure 2 is replaced by a plate including a semicircle 25 adapted to the shape and dimensions of the ascending column or the constraint limiter, a hinge 26, and another part 27 in a semicircle provided with a part 28 that it comes to be closed in a slot 29. The fixing means at the level of the slot, for example a bolt or bolt composed of a screw 30 and a nut 31 allow the maintenance of the upper part of the ascending column. A clamp is thus formed that can be opened easily, from which arises a facility of positioning of the ascending column. The height of this clamp may vary, according to the efforts that it will be necessary to collect. Figure 4 shows a variant embodiment of the maintenance device of figure 3 where each of the parts of the semicircle are provided on its internal wall with a groove 33, where the dimensions are adapted to the collar 34 placed on top of the ascending column. Figures 5A and 5B show two variants of embodiment of the maintenance device of figure 4. The throat in a single clamp is replaced by two clamps that enclose a stop (FIG. 5A) or two stops 36 (FIG. 5B) if the clamps are relatively distant from one another.

Figure 6 schematizes an application example of the invention for oil production where several hybrid ascending columns with references are used. Each riser includes a rigid part 41i and a flexible part 40i determined according to the method given above. A flexible part may be connected to a rigid part by a connector, the rising columns are autonomous from each other, the connector being located closer to the sea floor than to the surface. Without going outside the scope of the invention, it is also possible to regroup the different flexible parts at the level of a connector, the latter being able to form the connection or connection with a cluster that groups together the rigid parts of the ascending columns or even with a series or rigid ascending columns. According to another variant embodiment, several flexible parts can be grouped together by a connector, so as to be in connection with a single rigid part maintained at the level of the floating support.

Without going outside the scope of the invention, the rigid part includes, for example, thermal insulation means. It is also possible for the flexible part of the riser to employ a flexible riser provided with insulation or heating means. The use of the heating or insulation means on at least one of the two parts advantageously allows avoiding or minimizing the formation of deposits, for example of hydrates or paraffins in the context of the production of an oil effluent in deep seas, by example. The materials forming the rigid part and the flexible part of the rising column are chosen according to the fluid transported inside, in order to avoid any risk of deterioration such as corrosion or other damages resulting from the action of the fluid on the ascending column.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A conduit for large depths of water that allows the transfer of a fluid between a floating support and a point located below, and at a distance away from the surface of the water, characterized in that it includes: at least a flexible part in conjunction with one of its ends with the point located below the surface, and at least one rigid part in connection with the flexible part at one of its ends, and at the second end with the floating support, the rigid part having a length of at least equal at half the depth of the water D.

2. The conduit according to claim 1, characterized in that: the flexible part is defined as follows: a) the extreme movements of the floating support are established, b) it is assumed that the movements of the upper part of the flexible part are substantially identical to the extreme movements, c) the vertical position Ph of the upper end of this flexible part is chosen closer to the bottom of the water bed than of the surface, and the flexible part is dimensioned so as to collect at least the preset movements taking into account at least the following parameters: internal pressure Pint, external pressure Pext, the nature of the fluid, the maximum forces such as the maximum tensile Tmax considered by the flexible part, the value of the maximum admissible curvature courbmax if the flexible part does not respect the conditions of use, at least the position Ph, the rigid part defined by the given maintenance means and a diameter value Dr, e) its length Lr is chosen to be substantially equal to the value of the distance under the equilibrium conditions existing at the upper end of the flexible riser and the means of maintenance, in such a way that Lr is at least equal to half the depth D of the layer or bed of water, the value of its thickness is defined and in order to collect the constraints generated by at least: the weight of the conduit , the suspended weight of the flexible part, the hydrodynamic stresses, the forces induced by the displacements of the floating support, the internal and external pressures, f) it is seen rifica that the rigid part of the rising column that is placed inside or on the edges of the floating support does not come into contact with a floating support part, and eventually returns to stage b).

3. The duct according to claim 2, characterized in that the sizing steps of the flexible part and the rigid part are carried out in static conditions.

4. The duct according to claim 3, characterized in that the sizing is verified in static conditions by the sizing steps in dynamic conditions.

5. The duct according to claim 2, characterized in that the sizing steps of the flexible part and the rigid part are carried out under dynamic conditions.

6. The conduit according to any of claims 1 to 5, characterized in that it includes the thermal insulation means placed on at least the rigid part and / or the flexible part.

7. The conduit according to any of claims 1 to 6, characterized in that the rigid part is maintained in the floating support with the aid of maintenance means that allow the tensioning of said conduit under the effect of its own weight.

8. The riser column or production riser column according to any of claims 1 to 7, for the transfer of the effluents from a production well to a floating support.

9. The injection line or line according to any of claims 1 to 7, characterized in that the rigid part is in connection with a source of fluid to be injected, and the flexible part in conjunction with a site where the fluid must be injected.

10. The system for the production of oil effluents in large depths of water, which allows the transfer of a fluid between a floating support and a source of effluents, characterized in that it includes at least one or more ascending columns and / or one or more injection lines according to any of claims 1 to 8.

11. The system according to claim 10, characterized in that it includes a catenary anchoring system applied on the rigid ascending column, at the level of the connection and / or of the connector between the flexible part and the rigid part.

12. The production system according to any of claims 10 and 11, characterized in that it includes the supplementary means for putting the ascending columns or columns into tension.