EXTERNAL REINFORCEMENT STRUCTURAL APPARATUS FOR SUPPORTING bend STIFFENER AND METHOD OF INSTALLING THE STRUCTURAL APPARATUS IN AN OPERATIONAL ENVIRONMENT

Description

FIELD OF THE INVENTION

The present invention is part of the technical field of oil and gas, specifically related to pipeline and riser technologies, and refers to an external reinforcement structural apparatus for supporting the bend stiffener in bell mouths and the method of installing the structural apparatus in an operational environment in floating production units.

BACKGROUND OF THE INVENTION

Flexible risers are connected to platforms by means of end fitting connectors that support the loads related to the self-weight of the pipeline catenary and the hydrocarbon extraction process. To help reduce horizontal oscillations resulting from the displacement of the floating unit and the demands acting on the riser, devices are developed that mitigate the effect of lateral forces.

The vertical portion of the load derived from the flexible riser is supported in an area close to the structure deck (hang off) and the lateral forces are transferred to a connection device positioned close to the keel level of the floating unit, with a sliding coupling between such device and the riser.

A typical example of this device, which is normally applied in offshore environments, is the bell mouth (patent document PI 9605669-0). This disconnection between tensile support and absorption of lateral forces of flexible risers provides considerable operational benefits for this pipeline technology, such as, for example, increasing its useful life, but it is not limited to this.

In its turn, the absorption of lateral forces of flexible risers is commonly performed by a component called a flexural stiffener, responsible for providing a smooth transition of rigidity between the riser and the support system of the floating unit.

The bell mouth is an element designed over two decades ago to support the bend stiffener of flexible risers, ensuring that it is positioned at a suitable point.

This positioning of the bend stiffener support of flexible risers, assembled internally in the bell mouth, provides a concentration of loads and mechanical contact in specific regions of the assembly, normally referred to as the reaction torque in the bell mouth.

The mechanical contact between the bend stiffener support, and the internal geometry of the bell mouth, associated with an intrinsic clearance between these components to allow the coupling process, causes movements resulting from the oscillation of the production unit and the demands acting on the riser, causing friction movements that promote accelerated degradation in the metal surface of the bell mouth.

Although the degradation mechanism is still being studied, a significant loss of material thickness has been observed, thus compromising the resistance over the useful life of the assembly, promoting risks of loss of efficiency in the fixing of the bend stiffener support of flexible risers, maintenance of the bell mouth assembly and, in the event of extreme loads, a high risk of component failure.

In addition, it is important to highlight that it has currently been observed that the aggressive conditions of the marine environment, combined with factors such as the loads involved, the geometry of the bell mouths and failures in the corrosion protection system can initiate degradation processes in the component, compromising the structural capacity of the bell mouths.

Thus, the current scenario creates challenges: ensuring the functionality of riser stiffener supports with severe degradation and installing the solution while minimizing impacts on the production of the oil platform.

Due to the variables involved in operation, the loads of the flexible riser and the movements resulting from the operation, there is a decrease in the desired structural capacity for bell mouths, caused by localized degradation mechanisms of the material. This reduction directly impacts on the operation, increasing environmental risks and possible structural failure of the bell mouth, directly impacting production and leading to the need to implement a structural reinforcement mechanism.

Another important factor is the need to install the structural reinforcement with minimal impact on the production of the platform. In addition to seeking to reduce exposure of the divers to risk as much as possible, thus ensuring that the operation is economically viable and ensuring the integrity of the team involved in the operation.

When evaluating inspections and studies applied to equipment installed on operating platforms, a concentration of loads and problems with loss of thickness are observed in the central region of the bell mouth device, corresponding approximately to the height of the top region of the flexible riser stiffener cap. This weakened region is responsible for the increased risk of failures and the impossibility of using the equipment for a period longer than that specified during its design.

The trivial solution to solve this problem would be to replace the bell mouth with compromised structural capacity, requiring a prior disconnection of the flexible riser (pull-out), and then replace the bell mouth itself with an intact piece of equipment, finally reconnecting the flexible riser (pull-in).

However, it has been observed, through technical studies, that an increase in resistance in this region, a guarantee of limitation of movement of the helmet of the bend stiffener and a transfer of concentrated loads to an area of greater calculated resistance can guarantee a significant increase in the residual structural capacity of the bell mouth, in addition to promoting the reduction of operational risks to the production system of oil platforms in operation.

In view of the above, in order to solve the limitations and technical problems described above, the present invention describes an external reinforcement structural apparatus for supporting the bend stiffener and the method of installing the structural apparatus in an operational environment. The assembly of the structural reinforcement apparatus is developed for field application (submerged offshore environment at shallow depths), through the use of diving operations or even by ROV, without removing the bell mouth device from its application environment and using existing elements in its assembly for connection and transfer of loads, finally obtaining the technical advantages of guaranteeing the functionality of riser supports with severe degradation that are still in operation and installation of the solution, minimizing impacts on the production of the oil platform.

State of the Art

The document BR 102020025523-1 is part of the general state of the art and is based on the development of a solution for adaptation between types of bell mouths and is included in the field of activities of flexible pipeline risers and umbilicals with interface for bell mouths with BSN900E type connection in UEPs that have BSDL model bell mouths. The technical problem is related to the need to allow interchangeability between the two support systems, since the difference in the bell mouth interfaces prevents the interchangeability of the lines between the two types of support. The adapter developed in the document also comprises a split ring to be installed next to the bend stiffener helmet to allow interchangeability between the support systems.

The document resembles the present invention in some aspects, such as the fact that it also proposes a device to be used on the outside of a bell mouth and that also comprises a split ring. However, it should be noted that the technical problem and the purpose are different, the present invention is more related to proposing a solution to structurally reinforce the bell mouths, since aggressive conditions of the marine environment, combined with factors such as loads involved, geometry of the bell mouths and failures in the corrosion protection system can initiate degradation processes in the component.

In its turn, the document BR 102018011452-2 is related to pipeline and riser technologies, more particularly, related to systems and methods for connecting bend stiffeners in bell mouths. The technical problem is related to the fact that the state of the art lacks a fitting system between a bend stiffener and a bell mouth that has a reduced bend stiffener connection resistance effort, increasing the reliability of this operation and eliminating the need for shallow diving in parallel with the PLSV.

The system comprises a plurality of locking mechanisms in which each locking mechanism is externally fixed to the bell mouth and comprises a movable tab positioned in a downward inclined manner, the tab accessing the interior of the bell mouth and being actuated by an elastic element adapted to exert pressure on the tab towards the interior of the bell mouth.

Likewise, it is noted that this document is similar to the present invention in that it also proposes an external assembly installed on the bend stiffener/bell mouth. However, the external assembly of this document has the functionality of preventing the movement of the tabs during the operation of the bell mouth, not showing the structural reinforcement function proposed in the present invention.

Finally, the document BR 1020200254561 is also part of the general state of the art and is based on the development of a solution for the adaptation between different types of bell mouths and falls within the field of activities of flexible duct risers and umbilicals with interface for diverless bell mouth (BSDL) in UEPs that have bell mouths model BSN900E. The technical problem is associated with the need for adaptation technologies between different couplings with a technology capable of performing effectively and that is in accordance with the standardization recommendations.

According to the inventors, the adapter tool is capable of maintaining interchangeability and flexibility between projects or project phases, even if different bell mouth models are used. The tool is characterized by comprising an adapter split ring that, in the upper part, has geometry compatible with the swallowtail profile of the helmet model BSN900E and, in the lower part, has geometry compatible with the seating profile of the BSDL helmet.

Thus, the invention of the aforementioned document resembles the present invention because it also proposes a solution applied to bell mouths and bend stiffeners, with the presence of a split ring, holes, screws, etc. However, as in BR 102020025523-1, it is noted that the technical problem and the purpose are different, the present invention is more related to proposing a solution to structurally reinforce the bell mouths, since aggressive conditions of the marine environment, combined with factors such as loads involved, geometry of the bell mouths and failures in the corrosion protection system can initiate degradation processes in the component.

In view of these documents, it is clear that the present invention differs from the others in a fundamental technical aspect: only the structural apparatus of the present invention is capable of receiving the loads transferred by the mechanical contact of the stiffener support cap with the inside of the bell mouth, thus being effective in restoring the structural resistance of the bell mouth. And with that, increasing the resistance of the assembly, supporting the cyclic loads and the wear due to friction and corrosion.

In the aforementioned documents, there is no such solution. Considering the above, it is still possible to perceive relevant differences in the solutions shown in the state of the art in relation to the present invention and it is still possible to verify the presence of a differential technical effect in the present invention, considering the intrinsic advantages of the external reinforcement structural apparatus and its installation method.

It is important to highlight that the present invention offers advantages considering the economic and productivity impact, which is associated with the cost reduction with intervention in bell mouths with risks associated with weakening due to accentuated degradation, and the cost reduction in the possible need to replace stiffener supports for operation in wells with extended production time, also avoiding production stoppage, necessary in the case of the technical alternative of replacing the bell mouth.

Advantages in the health and safety aspect, since there is an increase in the resistance of the assembly supporting cyclic loads, wear due to friction and corrosion. And advantages related to reliability, since there is also a reduction in the risk of rupture by restoring the residual resistance of the bell mouth and consequently increasing the admissible top loads.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to an external reinforcement structural apparatus for supporting a bend stiffener to be integrated into the body of bell mouths, with this equipment in operation in floating production units. The present invention also relates to the method of installing the reinforcement structural apparatus in an operational environment in the bell mouth. During the installation activity, the bell mouth does not undergo any intervention in its functionality, initially undergoing cleaning and inspection processes for the execution of the assembly of the structural apparatus. The external reinforcement structural apparatus or mechanical force transfer assembly is manufactured in a partitioned form, to facilitate handling and assembly on the circular surface of the central body considering its installation through diving activities and can be improved for installation with the aid of ROV.

BRIEF DESCRIPTION OF THE FIGURES

In order to obtain a complete and total visualization of the object of this invention, the figures are indicated, to which references are made below.

FIG. 1 schematically represents a 3D view of the structural reinforcement apparatus for a bend stiffener support, being installed in the bell mouth.

FIG. 2 shows a schematic perspective view of a complete assembled bell mouth with locking ring (b) to be removed.

FIG. 3 shows a schematic representation of the structural reinforcement apparatus for extending the service life of bell mouths without being installed.

FIG. 4 shows a schematic perspective view of the external connection columns (1).

FIG. 5 shows a schematic perspective view of the connection jaws of the central ring (2) and the jaws of the lower connection (3).

FIG. 6 shows a schematic perspective view of the assembly of the partitioned lower ring (4).

FIG. 7 shows a schematic perspective view of the assembly of the external connection columns (1) in the bell mouth.

FIG. 8 shows a schematic perspective view of the application of the jaws of the lower connection (3).

FIG. 9 shows a schematic view of the central clamp in perspective.

FIG. 10 shows a schematic view of the central clamp assembly in perspective.

FIG. 11 shows a schematic representation of the complete set of the structural reinforcement apparatus for a bend stiffener support in the bell mouth.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an external structural reinforcement apparatus for supporting a bend stiffener to be integrated into the body of bell mouths, as shown in FIG. 1, in operation in floating production units. The present invention also relates to the method of installing the structural reinforcement apparatus in an operational environment in the bell mouth.

During the installation method, the bell mouth does not undergo any functional intervention, initially undergoing typical cleaning and inspection processes in these structures, as is commonly performed for other intervention operations in bell mouths (step a), for subsequent assembly of the structural apparatus. As shown in FIG. 2, to install the structural reinforcement apparatus it is necessary to remove the component called the locking ring (b).

As shown in FIG. 3, the structural reinforcement apparatus is composed of at least five subassemblies that can be pre-assembled prior to underwater operations to simplify their transportation and simplify the assembly process on the bell mouth body in its operational environment.

More specifically, the structural reinforcement apparatus comprises external connection columns (1), central ring connection jaws (2), lower connection jaw (3), partitioned lower ring (4), and inter-column connection clamp (5).

Each subassembly of the structural apparatus is composed of an external connection column (1) shown in FIG. 4, with the central ring connection jaws (2) and lower connection jaws (3) inserted, as shown in FIG. 5, fitted into the external connection columns (1) and prepositioned with hexagonal nuts.

In addition to these prepositioned items, the partitioned lower ring (4) shown in FIG. 6 will also be pre-assembled, rotated freely, on one of the columns (1) in order to facilitate the positioning rotation during the final assembly process of the subassemblies and their interconnection.

The assembly of the structural reinforcement apparatus or mechanical assembly for transferring forces over the bell mouth comprises a main upper fixation (step b), through the removal of the upper nuts from the upper flange fixing cases (c) for the assembly and fixing of the ears located above the set of columns (2), as shown in FIG. 7.

These nuts from the upper flange fixing cases (c) are removed and preferably the cases are replaced with new ones. Assembled as indicated in position (f) suitable for adjusting the positioning and distribution of loads according to the size of the bell mouth.

After assembling the column and pre-tightening the upper flange fixing cases (c), the clamps are fixed (step c), applied to establish contact with the central region of the central outer ring (d), also known as the “dog ring” and the lower part of the bell mouth “cone” (e), as shown in FIG. 8.

With the column subsets positioned according to the connection design and the clamps positioned, the column sets are joined with the aid of the central clamps (step d), FIG. 9. These central clamps are fixed by means of cases and nuts, thus ensuring the union of the subsets, in order to make it an integral element of circular structure, as shown in FIG. 10.

Once the central clamps have been joined, the lower partitioned rings (4) are positioned (step e), the contact of the force transmission elements is checked and the final tightening of the clamps (2) and (3) (step f), ensuring the complete assembly is fixed as shown in FIG. 11.

The assembly of the external reinforcement structural assembly may undergo variations in components and subassemblies to be assembled, according to the nominal diameter of the bell mouth and the application of different top loads derived from the riser in operation.

The assembly principle must ensure that the upper connection is made directly with the flange connection cases (c). It must also be noted that the lower connections (2) and (3) are connected to the dog support ring (d) and to the lower cone of the bell mouth (e), respectively.

The dimensioning of the apparatus or structural assembly must be carried out such that it is capable of receiving the loads transferred by the mechanical contact of the bend stiffener cap with the inside of the bell mouth, thus being effective in restoring the structural resistance of the bell mouth.

Those skilled in the art will appreciate the knowledge being indicated and will be able to reproduce the invention in the embodiments shown and in other variants, covered by the scope of the attached claims.