AND A SUBSEA TEMPLATE SYSTEM

Technical Field

The present disclosure relates to a method for providing a subsea template system with a tail pipe and a subsea template system. More particularly, the present disclosure relates to a subsea template system and how to put a tail pipe into a sea bed subsea and leave the tail pipe in the sea bed, in the oil and gas industry.

Background

A subsea template system is an underwater construction installed on the seabed as a foundation, support and protection for subsea oil and gas processing equipment, such as wells, Xmas trees, connection systems, piping, and valves. A subsea template system is rested on and is fixed to the seabed. Based on the soil conditions, the foundation method can be by suction anchors, piles, mudmats, or gravity based.

A subsea template system may support a guide pipe to guide a drill string, as is known from US2012/0298419. Here a guide pipe is drilled down into the seabed to receive and guide a drilling tool, and after drilling the guide pipe is removed. Drilling conductor casings into the seabed is known from, for example, US2917281 and US3732143. None of these uses a tail pipe. N020170948 discloses a tail pipe. US2002/0044839 discloses an apparatus used in helping penetrate the seabed. NO346267 discloses a subsea wellhead support system. US2013/0256030 discloses method of establishing a borehole in the seabed, comprising setting of a conductor. These documents may be useful for understanding the background.

A problem with a subsea template system during drilling is wash out, unwanted enlargement of the well, and that soil may fall into the drill hole. A problem is also to avoid flushing pipes. Flushing pipes may result in wash out. A further problem is well growth that may affect the subsea template system. It is desirable to solve these problems. It is desirable to have a subsea template system with good integrity, that is strong, and resistant to fatigue. It is also desirable that no cement and no drill cuttings are lost to the environment when a conductor is cemented in place.

A further problem is that operating the subsea template system takes place subsea, possibly at several thousand meters dept. This results in further problems such a high pressures, water current, darkness, presence of water, etc. The method and system must also comply with regulations and standards in the oil and gas industry.

A further technical problem is that any part of the subsea template system must function without a possibility to fail, fulfil technical and legal requirements, and be easy to use. It is desirable that any solution is simple, not expensive to produce, and is reliable. It is further a technical problem to avoid cumbersome arrangements that are expensive to manufacture or assemble.

Summary of the Invention

It is an object of the present invention to provide a method for providing a subsea template system with a tail pipe, and to provide a subsea template system. This object can be achieved by the features as defined by the independent claims. Further enhancements are characterized by the dependent claims. The invention is defined by the claims.

According to one embodiment, a method for providing a subsea template system with a tail pipe is disclosed. The subsea template system comprises a structure 100 and a tail pipe 200. The structure 100 comprises a guide 110 with an opening 120 for a well, and the structure 100 comprises a plurality of supports 102 for engaging a sea bed. The tail pipe 200 is cylindrical and comprises a serrated end structure 210 at a first end 202 of the tail pipe 200. The tail pipe 200 is arranged in the opening 120, and the tail pipe 200 comprises an interface 400 for rotating and axially move the tail pipe 200 relative to the structure 100. The method comprises placing 10 the structure 100 and the tail pipe 200 on the sea bed; rotating 20 and moving axially the tail pipe 200 relative to the guide 110 and into the sea bed to remain in the sea bed; drilling 30 with a tool 500, for example a drill string 500, an opening in the sea bed, inside the tail pipe 200, for an outer conductor casing 600; and installing 40 the outer conductor casing 600 and applying cement between the outer conductor casing 600 and the tail pipe 200. Further enhancements are characterized by the dependent claims.

According to one embodiment, a subsea template system is disclosed. The subsea template system comprises a structure 100 and a tail pipe 200. The structure 100 comprises a guide 110 with an opening 120 for a well, and the structure 100 comprising a plurality of supports 102 for engaging a sea bed. The tail pipe 200 is cylindrical and comprises a serrated end structure 210 at a first end 202 of the tail pipe 200, the tail pipe 200 being arranged in the opening 120. The tail pipe 200 comprises an interface 400 for rotating and axially move the tail pipe 200 relative to the structure 100. The guide 110 comprises a first guide 130 for the tail pipe 200, a second guide 140 for an outer conductor casing 600, and means for determining an end position for the tail pipe 200. Further enhancements are characterized by the dependent claims.

At least one of the embodiments disclosed herein provides one or more solutions to the problems and disadvantages with the background art. Other technical advantages of the present disclosure will be readily apparent to one skilled in the art from the following description and claims. Various embodiments of the present application obtain only a subset of the advantages set forth. No one advantage is critical to the embodiments. Any claimed embodiment may be technically combined with any other claimed embodiment or embodiments.

Brief Description of the Drawings

The accompanying drawings illustrate presently exemplary embodiments of the disclosure and serve to explain, by way of example, the principles of the disclosure.

Fig 1 is a diagrammatic illustration of a method for providing a subsea template system with a tail pipe according to an exemplary embodiment of the disclosure;

Fig 2 is a diagrammatic illustration of a subsea template system according to an exemplary embodiment of the disclosure;

Fig 3 is a diagrammatic illustration of a part of the subsea template system according to an exemplary embodiment of the disclosure;

Fig 4 is a diagrammatic illustration of a part of the subsea template system according to an exemplary embodiment of the disclosure;

Fig 5 is a diagrammatic illustration of a part of the subsea template system according to an exemplary embodiment of the disclosure; and

Fig 6 is a diagrammatic illustration of the subsea template system according to an exemplary embodiment of the disclosure;

Detailed Description

Figure 1 illustrates a method for providing a subsea template system with a tail pipe 200 according to an exemplary embodiment of the disclosure. Figures 2 to 6 illustrates a subsea template system according to an exemplary embodiment of the disclosure. Figure 6 illustrates also how an outer conductor casing 600 is installed inside the tail pipe 200. The outer conductor casing 600 may be a conductor 600 or a conductor housing 600. The method described herein may use any of the embodiments of the subsea template system described herein.

Turning to figure 1 , a method for providing a subsea template system with a tail pipe is illustrated. The method may install a tail pipe and an outer conductor casing. With reference to figures 1 and 2, the subsea template system used in the method comprises a structure 100 and a tail pipe 200. The structure 100 comprises a guide 110 with an opening 120 for a well, and the structure 100 comprises a plurality of supports 102 for engaging a sea bed 104. The tail pipe 200 is cylindrical and comprises a serrated end structure 210 at a first end 202 of the tail pipe 200. The first end 202 is the lower end 202 of the tail pipe 200, the end initially engaging the seabed 104. The tail pipe 200 is arranged in the opening 120, and the tail pipe 200 comprises an interface 400 for rotating and axially move the tail pipe 200 relative to the structure 100. More details of the subsea template system is described below.

With reference to figure 1 , the method for providing a subsea template system with a tail pipe comprises the following steps, preferably taken in order. Placing 10 the structure 100 and the tail pipe 200 on the sea bed 104; rotating 20 and moving axially the tail pipe 200 relative to the guide 110 and into the sea bed 104 to remain in the sea bed 104; drilling 30 with a drill string 500 an opening in the sea bed 104, inside the tail pipe 200, for an outer conductor casing 600; and installing 40 the outer conductor casing 600 and applying cement between the outer conductor casing 600 and the tail pipe 200. The outer conductor casing 600 may be a conductor 600 or a conductor housing 600.

According to one embodiment, and as illustrated in figures 2 to 6, the tail pipe 200 is a tube, a metal cylinder, with a serrated end structure 210. The serrated end structure 210 may be teeth, cutting formations, that assist the tail pipe 200 to cut its way into the seabed 104. The tail pipe 200 may be used initially before starting to drill the well. The tail pipe 200 herein described is not a tail pipe under a production packer. The tail pipe 200 is rotated and moved axially into the seabed 104 to remain permanently, for the life time of the well, several meters. In some situations only a portion of the tail pipe 200 may be drilled into the seabed 104, but it may be preferred to drill the tail pipe 200 completely, all the way, until its stop 220, into the seabed 104. To determine that the tail pipe 200 has been entered completely into the seabed, the guide 110 may comprise means for determining an end position for the tail pipe 200.

As illustrated by figure 1 , an embodiment of the method for providing a subsea template system with a tail pipe 200 may further comprise that the step of placing the structure 100 and the tail pipe 200 on the sea bed comprises installing 11 the structure 100 on the seabed 104; and subsequently installing 12 the tail pipe 200 into the guide 110 of the structure 100. The structure 100 may thus first be placed onto the seabed 104 and then the tail pipe 200 may be subsequently lowered into the guide 110 of the structure 100.

As illustrated by figures 1 and 2, for an embodiment of the method for providing a subsea template system with a tail pipe 200, the subsea template system may further comprise a temporary lock 300 for locking the tail pipe 200 relative to the guide 110. The step of placing the structure 100 and the tail pipe 200 on the seabed 104 may then comprise locking 13 the tail pipe 200 to the guide 110 with the temporary lock 300; installing 14 the structure 110 on a sea bottom; and releasing 15 the temporary lock 300. The tail pipe 200 may thus be locked, held firmly in place, inside the guide 110 as the structure 100 and the tail pipe 200 are placed on the seabed 104. Preferably the tail pipe 200 is locked in an upper position relative to the guide 110. Once the structure 100 and the tail pipe 200 are on the seabed 104 then the tail pipe 200 may be unlocked so that the tail pipe 200 can be moved into the seabed 104.

As illustrated by figures 1 and 4, for an embodiment of the method for providing a subsea template system with a tail pipe 200, the tail pipe 200 may further comprise an interface 400 for rotating 20 and axially move the tail pipe 200 relative to the structure 100. The step of rotating 20 and moving axially the tail pipe 200 relative to the guide 110 and into the seabed 104 to remain in the sea bed may comprise lowering 21 and connecting a tool 500, for example a drill string 500, to the interface 400; and rotating 22 the tool 500, such as for example a drill string 500, and thereby rotating the tail pipe 200, while applying weight on the tail pipe 200 to move the tail pipe 200 axially relative to the structure 100. The interface 400 may be adapted to receive a drill tool on the drill string 500. Once the tail pipe 200 has been installed in the seabed 104, then the same tool may be used to drill the opening inside the tail pipe 200. In this way one saves having to retrieve and deploy the drilling string 500. As illustrated by figures 1 and 4, for an embodiment of the method for providing a subsea template system with a tail pipe 200, the tail pipe 200 may further comprise an interface 400 for rotating 20 and axially move the tail pipe 200 relative to the structure 100. The step of rotating 20 and moving axially the tail pipe 200 relative to the guide 110 and into the seabed 104 to remain in the seabed 104 may comprise installing 23 a dedicated tool 510 on a drill string 500 for connecting the drill string 500 to the interface 400. A drill string 500 may be used for driving the tail pipe 200 into the seabed 104.

As illustrated by figures 1 and 4, for an embodiment of the method for providing a subsea template system with a tail pipe 200, the subsea template system may further comprise a stop 220 restricting axial downward movement of the tail pipe 200 relative to the structure 100. The step of rotating 20 and moving axially the tail pipe 200 relative to the guide 110 and into the seabed 104 to remain in the seabed 104 may comprise rotating 24 and moving axially the tail pipe 200 until the stop 220 restricts the axial move of the tail pipe 200 relative to the structure 100. The tail pipe 200 may freely move upwards, but the stop 220 prevents the tail pipe 200 to separate from the guide 110. The stop 220 may be used for determining an end position for the tail pipe 200 and may be a shoulder 150, a snap ring system, a visual indication, or other means.

For example, the axial move of the tail pipe 200 relative to the structure 100 may be stopped by the use of a flange 230 on the tail pipe 200 engaging a landing shoulder 150 arranged in the relative lower end of the guide 110, as best illustrated in figure 5. When the flange 230 engages the shoulder 150, then it can be determined that the end position has been reached. In another example, the tail pipe 200 may have a snap ring that is flexible so that it can snap into a groove on the guide 110, or the other way around. When the snap ring snaps into the groove, then it can be determined that the end position of the tail pipe 200 has been reached. In another example, the means for determining an end position may be a visual indicator such as a scale, or a meter, showing how much of the tail pipe 200 has been lowered relative to the guide 110. Such a scale or a meter can indicate and determine that the end position of the tail pipe 200 has been reached.

As illustrated by figures 1 and 6, for an embodiment of the method for providing a subsea template system with a tail pipe 200, the guide 110 may comprise a first guide 130 for the tail pipe 200, and a second guide 140 for the conductor casing 600. The outer conductor casing 600 may be a conductor 600 or a conductor housing 600. The method may further comprise rotating and moving axially the tail pipe 200 relative to the guide 110 while guiding the tail pipe 200 with the first guide 130, and installing the outer conductor casing 600 while guiding the conductor casing 600 with the second guide 140. In one embodiment, the guiding of the tail pipe 200 is done with only the first guide 130 and the guiding of the conductor casing 600 is done with only the second guide 140. By providing and guiding the tail pipe 200 using the first guide 130, and providing and guiding the outer conductor casing 600 using the second guide 140, it is possible to accurately and efficiently install the tail pipe 200 and the conductor 600, the outer conductor casing 600, into the seabed 104.

With reference to figures 2 to 6, a subsea template system is disclosed. The subsea template system comprises a structure 100 and a tail pipe 200. The structure 100 comprises a guide 110, the guide 110 comprising an opening 120 for a well. The structure 100 comprises a plurality of supports 102 for engaging a sea bed 104. The tail pipe 200 is substantially cylindrical and comprises a serrated end structure 210 at a first end 202, a first lower end 202, of the tail pipe 200. The tail pipe 200 is arranged in the opening 120 of the guide 110. The tail pipe 200 comprises an interface 400 for rotating and axially move the tail pipe 200 relative to the structure 100. The guide 110 comprises a first guide 130 for the tail pipe 200; a second guide 140 for an outer conductor casing 600; and means for determining an end position for the tail pipe 200.

According to one embodiment, the structure 100 may comprise one, two, three or four supports 102 for engaging the seabed 104. The structure 100 may comprise the guide 110 in a central position where the well is going to be, and the structure 100 may comprise radial arms and each arm stretches from the guide 110 substantially parallel to the seabed 104, in a horizontal direction, to one support 102. The guide 110 may be a hollow cylinder into which the tail pipe 200 and other pipping, such as the outer conductor casing 600 may be guided. The guide 110 may be arranged, preferably in a solid manner, in the central position of the structure 100, perpendicular to the radial arms, opening up towards the well. The structure 100 may comprise a plurality of guide rod receptacles. The receptacles may be used for installing guide rods onto the structure 100. The guide rods may be used for installing a blow out preventer, BOP, onto the wellhead. The guide rods may be attached to the structure 100 by being inserted and locked into the receptacles. According to one embodiment, the tail pipe 200 is a hollow cylinder, a metal cylinder, with a serrated end structure 210. The serrated end structure 210 may be teeth, cutting formations, that assist the tail pipe 200 to cut its way into the seabed. This allows the tail pipe to cut through even a hard seabed. The tail pipe 200 may be used initially before starting to drill the well. The tail pipe 200 herein described is not a tail pipe under a production packer. The tail pipe 200 is inserted into the ground to remain in the ground during the life time of the well, and thereafter if desired. The tail pipe 200 may be several meters long, for example over 6 meters long. Once the tail pipe 200 is installed, an opening may be drilled into the seabed inside the tail pipe and subsequently a conductor 600, an outer conductor casing 600, may be installed inside the tail pipe 200. The conductor 600 may be cemented in place by injecting cement between the inside of the tail pipe 200 and the outside of the outer conductor casing 600. This reduces the amount of cement or drill cuttings that may escape into the environment.

As may be taken best from figures 2 to 6, the first guide 130 may be separate from the second guide 140. The guides may be hollow cylinders. The first guide 130, for the tail pipe 200, may comprise two guides 130, one guide 130 arranged in the upper part of the guide 110 and one guide 130 arranged in the lower part of the guide 110. The landing shoulder 150 may operate and function as the guide 130 in the lower part of the guide 110. The one guide 130 arranged in the upper part of the guide 110 may be removably arranged on the guide 110. This to allow the upper guide to be used for guiding the tail pipe 200, then be removed so that an outer conductor casing may use a second guide 140 with a larger diameter. The second guide 140, for the outer conductor casing 600, may comprise two guides 140, one guide 140 arranged in the upper part of the guide 110 and one guide 140 arranged in the lower part of the guide 110. This arrangement is advantageous as it allows the guide 110 to guide the tail pipe 200 and the outer conductor casing 600 in one and the same guide 110. The guide 110 may be a well slot.

With reference to figures 2, 4 and 5, and according to an embodiment, the tail pipe 200 may further comprises a stop 220 restricting axial movement of the tail pipe 200 relative to the structure 100. The stop 220 may comprises a flange 230 on the tail pipe 200 for engaging a landing shoulder 150 arranged in the relative lower end of the guide 110. The flange 230 may be at the top end 204 of the tail pipe 200. The landing shoulder 150 may be at the lower end of the guide 110. The flange 230 may be an integral part of the tail pipe 200. The landing shoulder 150 may be an integral part of the guide 110. The stop 220 may give the end position for the tail pipe 200, and this end position may be below the outer conductor casing 600 interaction surfaces with the guide 110, that is below the lower guide 140 on the guide 110.

With reference to figures 2, 4 and 5, and according to an embodiment, the tail pipe 200 may further comprises a stop 220 restricting axial movement of the tail pipe 200 relative to the structure 100. The stop 220 may comprise a snap ring interacting with a groove. This alternative is not illustrated in the drawings. The snap ring may be arranged on the tail pipe 200 and the groove may be arranged in the lower part of the guide 110, or opposite. The groove may be give the end position for the tail pipe 200, and this end position may be below the outer conductor casing 600 interaction surfaces with the guide 110, that is below the lower guide 140 on the guide 110.

With reference to figure 4, and according to an embodiment, the interface 400 may be connectable to a drill string 500. The interface 400 may be part of the tail pipe 200 and allows the drill string 500 to connect to the tail pipe 200. The drill string 500 may then rotate and axially push the tail pipe 200 into the seabed 104. The interface 400 may be an adapter mounted onto the tail pipe 400. The interface 400 may be means for connecting, interfacing, with the drill string 500. The interface 400 may connect to the drill string 500 via a dedicated tool for this purpose on the drill string 500, or via a standard tool, such as a drill tool, that may be connected to the drill string 500.

With reference to figures 3 and 4, and according to an embodiment, the interface 400 may be connectable to a drive system 170 on the structure 100. The drive system 170 may be configured for rotating and moving axially the tail pipe 200 into the sea bed 104.

With reference to figure 2, and according to an embodiment, the subsea template system may further comprising a temporary lock 300 for locking the tail pipe 200 relative to the guide 110. This temporary lock 300 may be used when placing 10 the structure 100 and the tail pipe 200 onto the seabed 104. During the placing 10 the temporary lock 300 may be locked so that the tail pipe 200 is held firmly by the guide 110. Once placed, the temporary lock 300 may be unlocked so that the tail pipe 200 can be further moved into the seabed. The preferred locked position is illustrated in figure 2 where the first lower end 202 is closer to the guide 110 than the second higher end 204 of the tail pipe 200.

According to one embodiment, a further separate lock may be used to lock the tail pipe 200 relative to the guide 110 once the tail pipe 200 has been installed. The lock would prevent the tail pipe 200 from rotating during drilling and also prevent axial movement of the tail pipe 200.

With reference to figures 2 to 6, and according to an embodiment, the means for determining an end position for the tail pipe 200 may be a shoulder 150, a snap ring system, a visual indication, or other means. For example, the guide 110 may have a shoulder 150 and the tail pipe 200 a flange 230 for engaging the shoulder 150, as best illustrated in figure 5. When the flange 230 engages the shoulder 150, then it can be determined that the end position has been reached. In another example, the tail pipe 200 may have a snap ring that is flexible so that it can snap into a groove on the guide 110, or the other way around. When the snap ring snaps into the groove, then it can be determined that the end position of the tail pipe 200 has been reached. In another example, the means for determining an end position may be a visual indicator such as a scale, or a meter, showing how much of the tail pipe 200 has been lowered relative to the guide 110. Such a scale or a meter can indicate and determine that the end position of the tail pipe 200 has been reached.

With reference to figures 2 to 6, and according to an embodiment, the first guide 130 for the tail pipe 200 may be removable; and/or the first guide 130 for the tail pipe 200 may have a smaller inner diameter than the second guide 140 for the outer conductor casing 600. Preferably the upper first guide 130 may be removed from the guide 110 one the tail pipe 200 has been installed. In combination with this, or as an alternative, the first guide 130 for the tail pipe 200 may have a first inner diameter that may contact and guide the tail pipe 200. The second guide 140 for the outer conductor casing 600 may have a second inner diameter that may contact and guide the outer conductor casing 600. The first inner diameter may be larger than the second inner diameter. This is preferred since the installation of the outer conductor casing 600 is inside the tail pipe 200.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using the subsea template system and performing the methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.