MXPA06010355A - Method and system for starting up a pipeline - Google Patents

Abstract

The invention relates to a system for starting up an on-bottom pipeline (16) for transporting hydrocarbons, wherein said on-bottom pipeline (16) is extended on a seabed (12) from a wellhead (10) to a joint end (17) connected to a riser subsea (18) pipe which is suspended by a catenary, wherein said on-bottom pipeline (16) is embodied in such a way that it is extendable and the system comprises locking means for blocking said end joint on the seabed (12), thereby holding the on-bottom pipeline (16) in the extended position thereof.

Description

METHOD AND SYSTEM TO START A PIPING LINE FIELD OF THE INVENTION The present invention relates to a method and system for starting an appropriate flow line to transport hydrocarbons to be produced offshore. BACKGROUND OF THE INVENTION In accordance with known methods of the prior art, the flow lines, for example a line of rigid-type pipe, first extends over the seabed and is connected to a head of the oil production well. or with a multiplicity of well heads and its connecting end then "connected to the free end of an extended underwater riser" on a catenary, which by itself can be rigid. This underwater riser is designed to connect with a surface installation, such as a platform, for example. To make this connection, a known method involves horizontally connecting the submarine riser column with the connecting end of the flow line, essentially parallel with the surface of the seabed. After making the connections, the start-up of the flow line includes the transport of hydrocarbon, which reaches the extraction plant, through the flow line and the submarine upward column until the Ref .: 175545 surface installation. The submarine rising column is therefore placed completely on the seabed before making the connection with the use of remotely controlled robots (Remotely Operated Vehicle or ROV), which position themselves on either the flow line for pulling the riser with a cable, or on the free end of the underwater riser to pull it up to the connecting end of the flow line. The other end of the subsea ascending column is then lifted upwards to the surface installation. The method is remarkably illustrated in US Pat. No. 5,975,803. However, other known methods allow obtaining the same result. Therefore the submarine riser has a free end, which is connected to the mentioned connector end of the flow line, a first section, which extends over the seabed from this free end and an outlet section, which it extends asymptotically, just below the surface installation. A region called contact zone, which corresponds to a dynamic area of the ascending column, between the first section and the ascending column section has the capacity to characterize a point of contact which, in turn, is attracted against the bed marine, especially by the movements of surface installation. The flow line, on the other hand, has the ability to deform longitudinally. In a rigid pipe line, the hydrocarbon that passes through the extraction plant is also hot, which causes expansion and elongation of the flow line. In the flexible flow lines, the injection of the fluid under internal pressure also causes its elongation. The result of this is that there is a displacement of the connecting end of the flow line and of the first section of the submarine ascending column, by a distance of the order of 1 meter, for example 5 meters. However, the hydrocarbon pressure is not necessarily constant throughout the flow line and, additionally, the supply of the flow line may cease due to an incident or to allow a maintenance operation to be carried out in the extraction plant. Therefore there is a problem due to the dimensional variations of the flow line associated with the heating or cooling of the flow line or with a pressure variation, which can then cause not only the friction of the first section of the rising column underwater on the seabed, which can be abrasive, but also the variation in the radius of curvature of the marine rising column between this section and the elevation section or even the displacement of the position of the contact point on the pipe. These problems in particular contribute to its damage. SUMMARY OF THE INVENTION In accordance with the prior state of the art illustrated in Figure IA, the aforementioned problems are overcome by connecting the column-ascendant with the flow line using a flexible tube. Figure 1A shows an ascending column 1, which extends between a free end anchored in the seabed and a surface installation 2, and a flow line 3, whose connecting end 4, also anchored, is connected to the rising column 1 by a flexible tube 5. A first section 6 of the ascending column 1 is anchored to the blocks 7 outside the axis of the flow line 3 so that the dimensional variations in the flow line 3 are compensated by the deformation of the flexible tube 5. The latter, additionally, may comprise a rigid pipe member in U-shape with the ability to deform. The implementation of such a system is not profitable, since different anchor points must be created. A proposed problem, which the present invention seeks to solve, is to propose a method and a system for starting a flow line, which allows the useful life of submarine riser columns to be prolonged to avoid their friction on the seabed. and its deformation, at a convenient cost. For this purpose and in accordance with a first objective, the present invention proposes a method for starting a line "of appropriate flow to transport hydrocarbons, the flow line that extends on the seabed from a head of the well and that ends at one connector end, the connector end is suitable for connection with a rising column - submarine extended on a catenary, the method comprises a first stage, in which the elongation is induced flow; the method further comprises a second stage, in which the connector end is fixed with respect to the seabed to maintain the flow line in its tensioned position. It is therefore a feature of the invention to fix the connecting end of the flow line after it has been expanded and stretched, for example when the hot fluid is circulated through the flow line, this hot fluid it is, for example, hot water injected under pressure to evaluate the flow line. In this way, when the flow line cools because the hot water is no longer injected or the initially hot hydrocarbon stagnates in the flow line, the latter tends to contract, which induces internal stresses because it is maintained in its connector end, but its longitudinal dimensions do not vary. As a result, the deformations of the flow line no longer cause displacements of the submarine rising column, which is connected to it by the connecting end, so that this end is no longer damaged. ~ - In a particularly convenient manner, the displacement of the connector end in the direction of the elongation of the flow line is permitted and the displacement of the connector end in the opposite direction is not allowed. During the first stage, as the flow line deforms under the effect of temperature and tension, therefore it moves in translation and as soon as it cools and tends to contract, it is maintained under stress by the connector end, the which by: itself is kept fixed during the translation in the direction of the contraction of the flow line. In this way, the flow line can be set at its maximum deformation stage. Preferably, the connecting end is guided during the translation during the elongation of the flow line so that the shape of the fixing means, which will be described later, can be simplified. Moreover, in a favorable preliminary stage, the flow line is placed on the seabed and the subsea upward column is installed, then the subsea upward column is connected to the connecting end during the preliminary stage. In accordance with another object, the present invention proposes a system for starting an appropriate flow line to transport hydrocarbons, the flow line extends over the seabed from a wellhead and ends at a connector end, the connecting end is - suitable for connection with an underwater riser extended in a catenary, the flow line can be tensioned; the system comprises a fixing means for fixing the connector end with respect to the seabed to maintain the flow line in its tensioned position. The fastening means, which are described in the rest of the description, are fixed in solid form to the seabed and are anchored perfectly therein, they allow to keep the connector end in a fixed position with respect to the seabed. According to a particular embodiment, the fixing means includes a unidirectional retaining means suitable to allow the displacement of the connector end in the direction of elongation of the flow line and not to allow the displacement of the connector end in the opposite direction. In this way, the connector end can move in the direction opposite to the elongation of the flow line, which exerts a tensile force without this, and on the other hand, is immobilized in the opposite direction with respect to the seabed. Preferably, the system comprises a guiding means including a mobile trolley, for which the connecting end is suitable to be connected, the mobile trolley has the ability to slide on the means forming the rails. In this way, the connector end is perfectly guided during translation on the seabed in one direction, although the flow line does not necessarily deform uniformly and in one direction. The system comprises a base anchored in the seabed, the rails are fixed to the base in solid form, to perfectly anchor the truck and the connector end connected to it. Clearly, the base is appropriate to resist the traction exerted by the flow line while remaining motionless with respect to the seabed. According to a particularly favorable implemented characteristic of the invention, the unidirectional means comprises means forming a frame, mounted in the direction of the means forming the rails, and means forming a ratchet mounted on the truck, the means forming A ratchet are suitable for engaging in the means forming a frame. The means forming a ratchet are therefore suitable for the inclined coupling between two tines of the frame to disable the truck during the translation in one direction and also the rolling with respect to the tines, when the truck is attracted in the opposite direction due to to the elongation of the flow line. In accordance with a particularly favorable embodiment of the invention, the truck comprises a first receiver means suitable for receiving the connecting end of the flow line. In this way, as will be explained in more detail in the rest of the description, the flow line which is terminated by its' connector end is suitable to be installed in the receiving means, which itself is pre-installed, when unwinding the Flow line of the surface of a tube. Additionally, in accordance with a particular embodiment of the invention, the truck further comprises a second receiving means suitable for receiving a free end of the underwater riser to interconnect with the connecting end and the free end after the installation of the flow line. BRIEF DESCRIPTION OF THE FIGURES Other particular features and advantages of the invention will become apparent upon reading the description given below that refers to particular embodiments of the invention, provided solely as information without being a limitation, and in reference to the annexed figures in which: - Figure 1A is a schematic vertical sectional-transverse view of a system in accordance with the prior state of the art; Figure IB is a vertical cross-sectional view of a system according to the invention; Figure 2 is a schematic elevated view illustrating the elements of the system shown in Figure IB during a first phase of a preliminary stage of the installation method; Figure 3 is a schematic elevated view illustrating the elements of the system depicted in Figure IB during a second phase of the preliminary stage; Figure 4 is a schematic elevated view illustrating the elements of the system shown in Figures 2 and 3 at the end of the second phase; Figure 5 is a schematic view of a vertical section V-V through an element illustrated in Figure 4; Figure 6 is a schematic plan view of the elements illustrated in Figure 4; Figure 7 illustrates the system during an intermediate connection phase between the preliminary stage and a first stage, in which hot fluid is circulated through the flow line; Figures 8A-8B are schematic views of details showing two possible states of an element shown in Figure 7; Figure 9 is a schematic elevated view of the system illustrated in Figure 7 in a second step; Figure 10 is a schematic elevated view of the system illustrated in Figure 9 in an adjustment phase '; and Figure 11 shows elements of a system in accordance with an alternative modality during a preliminary phase of the implemented method. DETAILED DESCRIPTION OF THE INVENTION The structural elements of the system according to the invention: and, in parallel, its installation method will be described with reference to Figures 1 to 10. Figure IB illustrates a system according to the invention between a head of the well 10 located on the seabed 12 and a surface installation 14 suitable for recovering hydrocarbons and which is floating on the surface of the water 15. The system comprises a flow line 16 terminating at the connector end 17, resting on the seabed 12, and an underwater lifting column 18, which extends, which is connected to the surface installation 14. Prior to connection, this ascending column 18 has a free end 20, a first section 22, which rests on the seabed, and an asymptotic section 24, which is connected to the surface installation 14.

An essential feature of the invention, which is. detailed below, resides in the connection means 26 between the flow line 16 and the rising column 18, which allows to avoid the relative displacements of the connector end 17 and therefore the rising column 18 resulting from the deformation of the line of flow under the effect of temperature and pressure variations. Reference is now made to Figures 2 and 3 which illustrate in detail the method for installing the flow line 16 and the rising column 18. "Figure 2 shows the seabed 12 and the connecting end 17 of the flow line -16 during the installation Before the installation, a block or base 28 is anchored on the seabed 12 at a certain distance from the extraction plant 10. This base 28 has the 30 or sliding rails and a mobile trolley 32 which moves on these rails 30 in a direction oriented towards the extraction plant 10 and which will be described in greater detail in the remainder of the description Truck 32 here is in an initial off-center position of the plant. In addition, the truck 32 that the receiving means 34 must carry, comprising two receiving parts 35 that form a funnel, suitable for receiving a first connection unit 36, is mounted as a guide. n the connector end 17.

Therefore, the flow line 16 is placed from one. pipe surface not shown located on the base and then extending more or less vertically between the surface of the water 15 and the seabed 12. The connector end 17 is then guided, while the flow line is placed, so that the connecting unit 36 is adjusted vertically within the receiving part 35, located -to the extraction plant. It is understood that all -the well-known methods of rigid pipe laying are appropriate to be implemented, especially the methods -positioning known as "J" or "S" methods. Subsequently, the full flow line 16 is placed outside towards the extraction plant 10, and rotates at its connector end which is then maintained in a fixed position in a substantially horizontal plane, parallel to the seabed., by virtue of the connection unit 36 which itself holds itself in the receiving part 35, fixed itself in solid form to the truck 32 and the base 28. Figure 3 shows the flow line 16 installed in this way . After rotation the flow line 16, the connector end 17 is released and oriented in the direction of the other connection part 35. The riser 18, which has a second connection unit 38 mounted so as to rotate on the end 20 will be similarly installed and connected with the other receiving part 35. After unrolling the riser 18 such that its first section 22 is placed in contact with the seabed 12 in line with the flow line 16 but in the opposite direction, its free end, which has been rotated, is then positioned directed towards the connector end 17 of the flow line 16. Figures 4 and 5 show the connector end 17 directed towards and a distance of one meter, for example , from the free end 20, the truck 32, always remains in its initial inactive position. Moreover, the connector end 17 and / or the free end 20 are mounted sliding on a sleeve respectively, the it is mounted so that it rotates on the connection units 36 and 38 respectively. In this manner, with the use of a Remotely Operated Vehicle (ROV), the two contact ends 17 and 20 will be brought together with one another and interconnected imperviously to ensure the passage of hydrocarbon from the flow line 16 to the rising column. 18 without leakage Figure 7 also shows the two lines of pipe 16 and 18 connected by their ends 17 and 20. The above installation phases constitute a preliminary stage of the implementation method and, of the position in which the lines are connected of pipe, according to what is illustrated in Figure 7, a second step involves starting the pipe lines by injecting hot water, for example, into the flow line 16 from the extraction plant 10 to verify and test all The hot water lines are therefore recovered at a superficial end of the rising column 18. Like the hot hydrocarbon, which circulates through the over this, this hot fluid does not cause elongation of the flow line 16 so that the extreme connector 17 and the free end 20 which is now connected to it, are caused to move in a direction opposite to the plant. extraction 10, in the direction of the arrow F. The truck 32, which is fixed solidly during translation with the ends of the pipeline will therefore be handled in a similar manner during the translation along the rails 30 or slides from its initial position, as also shown in Figure 7 and in the direction of the arrow F. However, displacement in a translation of the truck 32 in the direction of the arrow F away from the plant is allowed. of extraction, while displacement to the extraction plant is not allowed due to the unidirectional retention means 39, which will be described in more detail with reference to Figures 5 and 8. The dimensional variations in the flow line occur here after the installation and connection of the flow line and the rising column, which are then lent in motion. However, in accordance with an alternative mode, the pressure and installation test of the flow line is considered before its connection. In this case, the connecting end of the flow line is restricted in translation, in the same way as before, after the elongation of the flow line by pressurization. The rising column then has the ability to be installed and connected to the flow line. Figure 5 illustrates a vertical cross section of the truck 32 and the base 28 on which the truck rests through the rails 30. Additionally, a frame 40 is solidly mounted on the base 28 on each side of the truck 32 near of the rails 30 and extends parallel to the rails 30 with the teeth oriented in the direction of the arrow F. Figure 8 shows part of the frame 40 and part of the chassis of the truck 32, which is suitable for sliding parallel to the frame 40. Moreover, Figure 8 illustrates a moving part 42 that forms a pawl in two possible states. A first state is shown in Figure 8A, in which the moving part has been rotated with respect to a frame tooth 40 and a second state shown in Figure 8B, in which the moving part 42 is engaged between two teeth of the frame. frame 40. The truck 32 therefore has the ability to be driven in translation in the direction of the arrow F, the moving part 42 then is suitable for turning with respect to the teeth and is restricted in the direction opposite to the arrow F , the moving part 42 is then coupled between the teeth. Additionally, the truck 32 is heavy enough and is maintained to slide on the rails 30 in a manner that is vertically restrained for the purpose, on the other hand, to prevent the truck 32 from leaving the rails 30 and, on the other hand, prevent the moving parts 42 from escaping from the frames 40. In this way the truck 32 is caused to move in the direction of the arrow F moving away from the extraction plant 10, as the flow line deforms longitudinally. On the other hand, as soon as the temperature of the fluid passing through the flow line 16 is reduced, it is restricted by the truck 32 which is itself restricted during the translation. Therefore, in a situation of maximum deformation as illustrated in Figure 9, the truck 32 is secured in a maximum active position and can not return to its initial position unless the moving parts 42 are released. As a result, once the system has been started under normal operating conditions, the temperature or pressure variations in the flow line no longer cause elongation of the flow line, which is then fixed in its elongation position maximum. However, the displacement means illustrated in Figure 10 are conditioned and are designed to readjust the position of the truck on the base 28 to decenter from the position of the contact point on the riser to prolong its useful life. The point of contact of the ascending column on the seabed is therefore displaced by varying the relative position of the free end of the ascending column 18 and of the installation _ superficial. These displacement means comprise, for example, a hydraulic pressure cylinder with one end firmly fixed to the rails 30 and the other end solidly fixed to the truck 32. Further in accordance with another embodiment of the invention, illustrated in the Figure 11, showing the base 28, the flow line 16 and the rising column 28 during installation, the connector ends 20 and 17 are pre-connected over the splice tube and the connection, which is assembled with a connection unit individual 48 to be adjusted in an individual receiving part 50, is guided to the base 28 with the use of a brace 52. Hereinafter and in the same way as in the previous variation the receiving part 50 which is solidly fixed to A wheelbarrow will be driven during translation in the direction of arrow F under the effect of elongation of flow line 16 and will be restricted during translation in the opposite direction. makes * state that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property. 1. A method to start an appropriate flow line to transport hydrocarbons, the flow line is extended on the seabed from a well head and ends at a connector end, the connector end is appropriate to connect with a column Underwater ascendant extended in a catenary, the method comprises a first stage, in which the elongation of the flow line is induced; _. . . The method is characterized in that it further comprises a second stage, in which the connecting end is fixed with respect to the seabed to maintain the flow line in its tensioned position. The method according to claim 1, characterized in that displacement of the connector end in the direction of elongation of the flow line is allowed and displacement of the connector end in the opposite direction is not allowed. The method according to claim 1 or 2, characterized in that the connecting end is guided during the translation during the elongation of the flow line. . The method according to any of claims 1 to 3, characterized in that it also comprises a preliminary stage, in which the flow line is placed on the seabed and the submarine riser column is installed. 5. The method according to claim 4, characterized in that the underwater riser is connected to the connecting end during the preliminary stage. 6. A system to start an appropriate flow line to transport hydrocarbons, the flow line is extended on the seabed from a well head and ends at a connector end, the connector end is "suitable for connecting with an underwater column in a catenary, the flow line has the ability to tighten, the system is characterized in that it comprises a fixing means to fix the connector end with respect to the seabed to maintain the flow line in its tensioned position 7. The system according to claim 6, characterized in that the fixing means includes a unidirectional retention means appropriate to allow the displacement of the connector end in the direction of elongation of the flow line and to restrict the displacement of the connector end in the opposite direction. 8. The system according to claim 7, characterized in that it comprises a guiding means that includes a mobile trolley, to which the connecting end is suitable to be connected, the mobile trolley has the capacity of 5 slide over remedies that form the rails. 9. The system according to claim 8, characterized in that it comprises a base anchored on the seabed, the rails are fixed solidly to the base. The system according to claim 8 or -10 9, characterized in that the unidirectional means comprises means forming a frame, mounted in the direction of the means forming the rails, and means forming a ratchet mounted on the truck, the means forming a ratchet is suitable for engaging in the means forming a frame. 11. The system according to any of claims 8 to 10, characterized in that the truck comprises a first receiver means suitable for receiving the connector end. 12. The system according to claim 9, 20 characterized in that the truck further comprises a second receiving means suitable for receiving a free end of the underwater riser to interconnect the connecting end and the free end.