Subsea connection technique

Abstract

A method of changing a subsea connection type, the method comprising: detaching, by a subsea process, a subsea bolted connection to a pipe and / or a termination 101; and adapting, by a subsea process,

Description

Field of the Invention The present invention relates to a method of adapting a subsea connection and to products used in the method. Background Subsea pipes, such as pipelines and risers, are commonly used in the oil and gas industries to transport substances underwater. There is a general need to improve on known techniques with subsea pipes and risers. Summary of the Invention Aspects of the invention are set out in the appended independent claims. Optional aspects are set out in the dependent claims. Description of the Drawings The present invention will now be described, by way of non-limitative example only, with reference to the following figures, in which: Figure 1 schematically shows a known subsea pipe connection as may be used in the offshore oil industry; Figure 2 shows a Vertical Connection Installation Frame, VCIF, tool according to an embodiment; Figures 3A and 3B show the installation of a flange insert around the end of a riser according to an embodiment; Figures 4A and 4B show steps in the connection between the end of a riser and the end of a tie-in pipe according to an embodiment; and Figures 5A to 5E schematically show steps in the connection process between the end of a riser and the end of a tie-in pipe according to an embodiment. Detailed Description Figure 1 schematically shows a known subsea pipe connection as may be used in the offshore oil industry. The pipe connection may be at any sea depth and, for example, may be 300m to 1500m below the sea surface. The subsea pipe connection is comprised by a riser support base 107. The riser support base 107 may sit on a sea floor 104 or be supported from above. The riser support base 107 may house the lower end of a riser 101 that is a vertical pipe to the sea surface. The main structural support of the riser 101 may be from above, and the riser support base 107 may not provide substantial, or any, structural support to the riser 101. There may also be a tie-in pipe 102 that lies on the sea floor 104 and is connected to the riser 101. The end of the tie-in pipe 102 that is connected to the riser 101 may be a spool. The riser support base 107 may support the subsea connection between the riser 101 and the tie-in pipe 102. Although not shown in Figure 1, the riser support base 107 may support a connection between a plurality of risers 101 and a respective plurality of tie-in pipes 102. The sea floor 104 end of the riser 101 may have a flange 106. The tie-in pipe 102 may also have a corresponding flange 105. The flange 106 of the riser 101 may be connected to the flange 105 of the tie-in pipe 102 so as to connect the riser 101 and the tie-in pipe 102. The connection may be nuts and bolts 103, with the bolts extending through the flange 106 and the flange 105. It may be necessary to change the tie-in pipe 102 that is connected to the riser 101. For example, the tie-in pipe 102 may be damaged and need to be replaced. 2 The known technique for changing the tie-in pipe 102 that is connected to the riser 101 requires unscrewing the nuts and bolts 103 so that the tie-in pipe 102 is detached from the riser 101, moving the existing tie-in pipe 102 out of the riser support base 107, bringing a new tie-in pipe 102 into the riser support base 107, and then bolting the new tie-in pipe 102 to the riser 101. A problem with known techniques is that the process of changing the tie-in pipe 102 that is connected to the riser 101 is slow, complicated and expensive. In particular, the process of attaching bolts to a flange at greater depths than human divers can operate is difficult. Embodiments provide a new technique for changing the tie-in pipe that is connected to the riser 101. The techniques of embodiments may be faster, easier more reliable and cheaper than known techniques. According to embodiments, a Vertical Connection Installation Frame, VCIF, tool is used to remove the bolts 103 that connect the tie-in pipe to the riser 101. The bolts 103 may be cut through so that they do not need to be unscrewed. The same VCIF tool is then used to connect the new tie-in pipe to the riser with a connection that does not require the use of nuts and bolts, such as a clamp, press fit, hub, and / or collet based connection. Embodiments are described in more detail below. Figure 2 shows a Vertical Connection Installation Frame, VCIF, tool according to an embodiment. The VCIF tool comprises a top structure 202 and a bottom structure 207. The top structure 202 comprises guide pins 201, a plurality of winches 206, a panel and receptacles 205 for a remotely operated vehicle (ROV), and bottom structure guide pins 203. The bottom structure 207 may be connected the top structure 202 by fibre ropes connected to the ends of the bottom structure guide pins 203. The bottom structure 207 may be lifted 3 into the top structure 202 accurately and with a large force applied by the plurality of winches 206 acting on the fibre ropes. The bottom structure guide pins 203 may be received in guide funnels of the top structure 202. The bottom structure 207 may be used to hold, align and manipulate the tooling that is used to cut through, or apply another technique for removing, nuts and bolts so that an existing tie-in pipe 102 may be removed from a riser 101. The bottom structure 207 may be used to clamp onto and hold the end of the tie-in pipe 102, that may be a spool, as it is being disconnected and moved away from end of the riser 101. The bottom structure 207 may be used to hold any auxiliary tooling that is required, such as a seal groove cleaning tool and a seal insertion tool. The bottom structure 207 may be used to hold, align and secure the new tie-in pipe to the riser 101. A process for changing a tie-in pipe according to embodiments is described below. An ROV may be used to open any protection doors around the subsea pipe connection, and any doghouse covering flange, so that the connection between the riser 101 and the tie-in pipe 102 may be accessed. A VCIF tool may be lowered into position next to the riser support base 107. An ROV may then push the guide pins 201 on the top structure 202 of the VCIF tool into docking probe receptacles on the riser support base 107. The VCIF tool may then be secured to the riser support base 107. Pre-installed in the bottom structure 207 of the VCIF tool may be a tool for cutting nuts and bolts 103 and a tool for gripping the tie-in pipe 102. The bottom structure 207 may be 4 lifted and aligned so that the tool for cutting nuts and bolts 103 is in an appropriate location for cutting the nuts and bolts 103. The tool for gripping the tie-in pipe 102 may then be activated so that the bottom structure 207 is secured to the tie-in pipe 102. The tool for cutting nuts and bolts 103 may then be activated so that a saw, such as a rotational saw, cuts through the nuts and bolts 103. The tool for cutting nuts and bolts 103 may alternatively, or additionally, cut through the riser 101 pipe to remove the flanges 106, 105 or cut through the tie-in pipe 102. Embodiments also include other techniques for disconnecting the riser 101 and tie-in pipe 102, such as a tool for unscrewing the nuts and bolts 103. After the riser 101 and tie-in pipe 102 are detached from each other, the winches 206 may be operated so that the bottom structure guide pins 203 are lowered out of the guide funnels of the top structure 202. The end of the tie-in pipe 102 is thereby securely lowered away from the end of the riser 101. After the bottom structure guide pins 203 are completely out of the guide funnels of the top structure 202, the released end of the tie-in pipe 102 may be connected to the end of a crane that is on a surface vessel. The crane may then lower the end of the tie-in pipe 102 so that it lies on the sea floor 104. The tool for cutting nuts and bolts 103 and the tool for gripping the tie-in pipe may then be released from the bottom structure 207 of the VCIF tool. The bottom structure 207 of the VCIF tool may then be removed from the end of the tie-in pipe 102. The bottom structure 207 of the VCIF tool may then be landed by the crane on the sea floor 104 and attached to the of a new tie-in pipe. The end of the new tie-in pipe may have an end connector that is suitable for a clamp, press fit, hub, and / or collet based connection. The connection may be, for example, a MORGRIP® Connector, as sold by Connector Subsea Solutions (see https: / / connectorsubsea.com / morgrip-connectors / as viewed on 30 April 2022). The crane may then lift the bottom structure 207 of the VCIF tool, that is attached to the new tie-in pipe, so that it is positioned near to, and under, the end of the riser 101. The winches 206 may then be operated so that the bottom structure guide pins 203 are pulled into the guide funnels of the top structure 202. The bottom structure guide pins 203 may be pulled only part of the full distance into the guide funnels of the top structure 202 so that the ends of the riser 101 and the new tie-in pipe are separated from each other. A flange insert 302 may then be installed around the end of the riser 101, and Figures 3A and 3B show steps in this process. The flange insert 302 adapts the end of the riser 101 so that it may connect with the end of the new tie-in pipe 301. The flange insert 302 may comprise a first part 302a and a second part 302b that are separately installed. The first part 302a of the flange insert 302 may be installed first by an ROV, or an installation tool, securing it to the end of the riser 101. For example, an ROV may secure the first part 302a to the end of the riser 101 by operating an ROV handle 303 that is attached to the first part 302a. The ROV may then secure the second part 302b to the end of the riser 101 and / or the first part 302a by operating an ROV handle 303 that is attached to the second part 302b. The ROV handles 303 may then be removed from the first part 302a and the second part 302b. As shown in Figure 3B, a flange insert 302 may thereby be provided around the end of the riser 101. The first part 302a and the second part 302b of the flange insert 302 may be symmetrical across the diameter of the riser 101. A seal grove cleaning tool 304 may then be installed, by an ROV, on top of the end of the new tie in pipe 301. The winches 206 may then be operated to pull the bottom structure guide pins 203 further into the guide funnels of the top structure 202 so that the bottom structure 207 of the VCIF tool is lifted. The seal grove cleaning tool 304 may then be appropriately aligned and operated to clean, and / or otherwise condition, the end of the riser 101. The winches 206 may then be operated to lower the bottom structure 207 of the VCIF tool and the seal grove cleaning tool 304 removed by an ROV. The end of the new tie in pipe 301 may have a pressure cap pre-installed. This may then be removed by an ROV. A seal ring may then be installed in the end of the new tie in pipe 301. As shown in Figures 4A and 4B, the process of attaching the end of the riser 101 and the end of the new tie-in pipe 301 may then be performed. The winches 206 may be operated to pull the bottom structure guide pins 203 further into the guide funnels of the top structure 202 so that the bottom structure 207 of the VCIF tool is lifted. This brings the connecting parts of the end of the riser 101 and the end of the new tie-in pipe 301 together. As shown in Figure 4A, the flange insert 302 may be mated with a connecting part 401 of the connector at the end of the new tie-in pipe 301. The connection mechanism may then be activated, as shown in Figure 4B, so that the connecting parts of the end of the riser 101 and the end of the new tie-in pipe 301 are securely locked together and the connection between the end of the riser 101 and the end of the new tie-in pipe 301 is complete. The integrity of the connection between the riser 101 and the new tie-in pipe 301 may then be tested, such as pressure tested. The VCIF tool may then be released, removed and returned to the surface vessel. Other finishing operations may then be performed, such as securing the new tie-in pipe 301 to the riser support base 107, applying insulation, closing doors of the riser support base 107 etc. Figures 5A to 5E schematically show the connection process between the end of the riser 101 and the end of the new tie-in pipe 301. Figure 5A shows the end of the new tie-in pipe 301 when held by the bottom structure 207 of the VCIF tool but before it has been brought into position for connection to the end of the riser 101. Figure 5B shows the end of the new tie-in pipe when held by the bottom structure 207 of the VCIF tool and in position for connection to the end of the riser 101. The flange insert is not shown in Figure 5B. Figure 5C shows the end of the new tie-in pipe when held by the bottom structure 207 of the VCIF tool and in position for connection to the end of the riser 101. The flange insert is shown in Figure 5C. Figure 5C shows the flange insert 302 after it has been attached to the end of the riser 101 and before the connection mechanism 501 has been activated. Figure 5D shows the end of the riser 101 and the end of the new tie-in pipe 301 securely locked together after the connection mechanism has been activated. Figure 5E shows the final clamp based connection after the VCIF tool has been removed. Accordingly, embodiments provide a new technique for connecting a tie-in pipe 301 to a riser 101. A riser 101 that was originally designed for a bolted connection to a tie-in pipe may be adapted so that a clamp, press fit, hub, and / or collet based connection is used instead. Advantageously, embodiments provide a quicker, simpler, more reliable and less expensive pipe connection process. Embodiments include a number of modifications and variations to the above-described techniques. In particular, the connector at the end of the new tie-in pipe 301, and the connection process, may be different from that described above. For example, the connection process between the end of the riser 101 and the end of the new tie-in pipe 301 may alternatively comprise the winches 206 pulling the end of the new tie-in pipe 301 into the end of the riser 101, with the activation of a separate connection mechanism not being required. 8 The VCIF tool according to embodiments may be substantially the same as, or similar to, the VCIF tool disclosed in EP3359770 Al, the entire contents of which is incorporated herein by reference. The process of removing nuts and bolts so that an existing tie-in pipe 102 may be removed from a riser 101 may comprise cutting through the nuts and / or bolts, as described above. Embodiments also include the nuts and bolts being removed by a tool unscrewing them. The installation and use of the flange insert 302 is optional. In particular, embodiments include providing the connection between the riser 101 and the new tie-in pipe 301 without installing a flange. The connection may comprise a connector that covers the end of the riser 101. Embodiments have been described in the context of the tie-in pipe that is connected to a riser 101 being replaced by a new tie-in pipe. Embodiments also include the techniques being performed so as to change the type of connection between a tie-in pipe and the riser 101. Embodiments are as described above but further include a step of adapting the end of the tie-in pipe after it has been detached from the riser 101. The end of the tie-in pipe may be adapted by, for example, an ROV attaching a new connector to the end of the tie-in pipe. Alternatively, the detached tie-in pipe may be brought up to a vessel on the sea surface where a new connector is attached to the end of the tie-in pipe. Embodiments are not restricted to the specific scenario of changing the connection between a tie-in pipe and a riser 101. Embodiments more generally include changing the connection between any subsea pipes, or any subsea connection between a termination and a pipe. For example, two horizontally aligned subsea pipes may be connected by bolts. Embodiments may be used to replace one of the subsea pipes with a new pipe with the connection to the new pipe being a clamp, press fit, hub, and / or collet based connection instead of a bolted connection. The accompanying drawings are provided for purposes of illustration only, and the dimensions, positions, order, and relative sizes reflected in the drawings attached hereto may vary. The detailed description will be better understood in conjunction with the accompanying drawings, with reference made in detail to embodiments of the present subject matter, examples of which are illustrated in the drawings. Each example is provided by way of explanation of the present subject matter, not limitation of the present subject matter. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope of the present subject matter. Thus, it is intended that the present subject matter covers such modifications and variations as come within the scope of the appended claims and their equivalents. In the foregoing description, it will be appreciated that the phrases “at least one”, “one or more”, and “and / or”, as used herein, are open-ended expressions that are both conjunctive and disjunctive in operation. The term “a” or “an” entity, as used herein, refers to one or more of that entity. As such, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, longitudinal, front, back, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise, counterclockwise, and / or the like) are used for identification purposes to aid the reader’s understanding of the present disclosure, and / or serve to distinguish regions of the associated elements from one another, and do not limit the associated element, particularly as to the position, orientation, or use of this disclosure.

Claims

1. A method of changing a subsea connection type, the method comprising: detaching, by a subsea process, a subsea bolted connection to a pipe and / or a termination; andadapting, by a subsea process, the connection to the pipe and / or the termination so that it is configured for a clamp, press fit, hub, and / or collet based connection.

2. The method according to claim 1, wherein the subsea bolted connection is between a first tie-in pipe and said pipe and / or said termination; andthe method further comprises moving the first tie-in pipe away from the location of the connection to said pipe and / or said termination;moving a second tie-in pipe, that is configured for a clamp, press fit, hub, and / or collet based connection, to the location of the connection to said pipe and / or said termination; andconnecting the second tie-in pipe to said pipe and / or said termination via a clamp, press fit, hub, and / or collet based connection.

3. The method according to claim 2, wherein detaching the bolted connection between the first tie-in pipe and said pipe and / or said termination comprises one or more of cutting through bolts, cutting through nuts, cutting through the first tie-in pipe, and cutting through said pipe and / or said termination.

4. The method according to any preceding claim, wherein adapting the connection to said pipe and / or said termination comprises attaching a flange insert to said pipe and / or said termination.

5. The method according to any preceding claim, wherein said pipe and / or said termination is a riser.

6. The method according to claim 5, wherein the connection location is in a riser support base.

7. The method according to claim 6 when dependent on claim 2, further comprising securing, in a subsea process or subsea processes, one or more parts of a subsea tool on one or more of the riser support base, the first tie-in pipe, the second tie-in pipe, and the riser;wherein the subsea tool is configured to perform and / or assist with one or more of: detaching the subsea bolted connection;moving the first tie-in pipe;moving the second tie-in pipe;adapting the connection to the riser; and connecting the second tie-in pipe to the riser.

8. A subsea tool configured to perform the method according to any preceding claim.

9. A pipe system comprising:a pipe and / or a termination; anda tie-in pipe connected, by a clamp, press fit, hub, and / or collet based connection, to said pipe and / or said termination;wherein said pipe and / or said termination has been adapted for the connection to the tie-in pipe according to the method of any of claims 1 to 7.

10. A riser system comprising:riser support base that houses a subsea connection between a tie in pipe and a riser; a riser; anda tie-in pipe connected, by a clamp, press fit, hub, and / or collet based connection, to the riser;wherein the riser has been adapted for the connection to the tie-in pipe according to the method of any of claims 1 to 7.

11. A flange insert for converting a bolted subsea connection to a clamp, press fit, hub, and / or collet based subsea connection;wherein the flange insert is configured for use in the method according to claim 4.

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