Method for Providing a Subsea Template System with a Tail Pipe and a Subsea Template System

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 seabed subsea and leave the tail pipe in the seabed, in the oil and gas industry.

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, Christmas (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. 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, but none use a tail pipe.

A problem with subsea template systems during drilling is washout, i.e, an unwanted enlargement of the well, and that soil may fall into the drill hole. Another problem is to avoid flushing pipes, in which flushing pipes may result in washout. 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 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 depth. This results in further problems such as 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 of failing, fulfill technical and legal requirements, and be easy to use. It is desirable that any solution is simple, not expensive to produce, and reliable. It is further a technical problem to avoid cumbersome arrangements that are expensive to manufacture or assemble.

According to embodiments of the present disclosure, a method for providing a subsea template system with a tail pipe and to provide a subsea template system are disclosed herein. This can be achieved by the features as defined by the independent claims. Further enhancements are characterized by the dependent claims. The embodiments are further 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 and a tail pipe. The structure comprises a guide with an opening for a well, and the structure comprises a plurality of supports for engaging a seabed. The tail pipe is cylindrical and comprises a serrated end structure at a first end of the tail pipe. The tail pipe is arranged in the opening, and the tail pipe comprises an interface for rotating and axially move the tail pipe relative to the structure. The method comprises placing the structure and the tail pipe on the seabed; rotating and moving axially the tail pipe relative to the guide and into the seabed to remain in the seabed; drilling with a tool, for example a drill string, an opening in the seabed, inside the tail pipe, for an outer conductor casing; and installing the outer conductor casing and applying cement between the outer conductor casing and the tail pipe. 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 and a tail pipe. The structure comprises a guide with an opening for a well, and the structure comprising a plurality of supports for engaging a seabed. The tail pipe is cylindrical and comprises a serrated end structure at a first end of the tail pipe, the tail pipe being arranged in the opening. The tail pipe comprises an interface for rotating and axially move the tail pipe relative to the structure. The guide comprises a first guide for the tail pipe, a second guide for an outer conductor casing, and means for determining an end position for the tail pipe. 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.

illustrates a method for providing a subsea template system with a tail pipeaccording to an example embodiment of the disclosure.illustrate a subsea template system according to an example embodiment of the disclosure.illustrates also how an outer conductor casingis installed inside the tail pipe. In embodiments, the outer conductor casingis a conductoror a conductor housing. The method described herein may use any of the embodiments of the subsea template system described herein.

Turning to, a method for providing a subsea template system with a tail pipe is illustrated. In embodiments, the method installs a tail pipe and an outer conductor casing. With reference to, the subsea template system used in the method comprises a structureand a tail pipe. The structurecomprises a guidewith an openingfor a well, and the structurecomprises a plurality of supportsfor engaging a seabed. The tail pipeis cylindrical and comprises a serrated end structureat a first endof the tail pipe. The first endis the lower endof the tail pipe, the end initially engaging the seabed. The tail pipeis arranged in the opening, and the tail pipecomprises an interfacefor rotating and axially move the tail piperelative to the structure. More details of the subsea template system is described below.

With reference to, the method for providing a subsea template system with a tail pipe comprises the following steps. Placingthe structureand the tail pipeon the seabed; rotatingand moving axially the tail piperelative to the guideand into the seabedto remain in the seabed; drillingwith a drill stringan opening in the seabed, inside the tail pipe, for an outer conductor casing; and installingthe outer conductor casingand applying cement between the outer conductor casingand the tail pipe. In embodiments, the outer conductor casingis a conductoror a conductor housing.

According to one embodiment, and as illustrated in, the tail pipeis a tube, a metal cylinder, with a serrated end structure. In embodiments, the serrated end structureare teeth, i.e., cutting formations, that assist the tail pipeto cut its way into the seabed. The tail pipemay be used initially before starting to drill the well. The tail pipeherein described is not a tail pipe under a production packer. The tail pipeis rotated and moved axially into the seabedseveral meters to remain permanent for the lifetime of the well. In some situations, only a portion of the tail pipeis drilled into the seabed, however, in some instances, the tail pipeis drilled completely, all the way, until its stop, into the seabed. To determine that the tail pipehas been entered completely into the seabed, the guidecomprises a means for determining an end position for the tail pipe.

As illustrated by, the method step of placing the structureand the tail pipeon the seabed further comprises installingthe structureon the seabed, and subsequently installingthe tail pipeinto the guideof the structure. Thus, in embodiments, the structureis first placed onto the seabedand then the tail pipeis subsequently lowered into the guideof the structure.

As illustrated by, for an embodiment of the method for providing a subsea template system with a tail pipe, the subsea template system further comprises a temporary lockfor locking the tail piperelative to the guide. The step of placing the structureand the tail pipeon the seabedthen comprises lockingthe tail pipeto the guidewith the temporary lock; installingthe structureon a sea bottom; and releasingthe temporary lock. In embodiments, the tail pipeis locked, held firmly in place, inside the guideas the structureand the tail pipeare placed on the seabed. In a further embodiment, the tail pipeis locked in an upper position relative to the guide. Once the structureand the tail pipeare on the seabed, then the tail pipemay be unlocked so that the tail pipecan be moved into the seabed.

As illustrated by, for an embodiment of the method for providing a subsea template system with a tail pipe, the tail pipefurther comprises an interfacefor rotatingand axially move the tail piperelative to the structure. In embodiments, the step of rotatingand moving axially the tail piperelative to the guideand into the seabedto remain in the seabed comprises loweringand connecting a tool, for example a drill string, to the interface; and rotatingthe tool, such as for example a drill string, and thereby rotating the tail pipe, while applying weight on the tail pipeto move the tail pipeaxially relative to the structure. In embodiments, the interfaceis adapted to receive a drill tool on the drill string. Once the tail pipehas been installed in the seabed, the same tool may be used to drill the opening inside the tail pipe. In this way, one saves having to retrieve and deploy the drilling string.

As illustrated by, for an embodiment of the method for providing a subsea template system with a tail pipe, the tail pipefurther comprises an interfacefor rotatingand axially move the tail piperelative to the structure. In embodiments, the step of rotatingand moving axially the tail piperelative to the guideand into the seabedto remain in the seabedcomprises installinga dedicated toolon a drill stringfor connecting the drill stringto the interface. In embodiments, a drill stringis used for driving the tail pipeinto the seabed.

As illustrated by, for an embodiment of the method for providing a subsea template system with a tail pipe, the subsea template system further comprises a stoprestricting axial downward movement of the tail piperelative to the structure. In embodiments, the step of rotatingand moving axially the tail piperelative to the guideand into the seabedto remain in the seabedcomprises rotatingand moving axially the tail pipeuntil the stoprestricts the axial move of the tail piperelative to the structure. In embodiments, the tail pipeis permited to move upwards freely, but the stopprevents the tail pipefrom separating from the guide. In embodiments, the stopis used for determining an end position for the tail pipeand may be a shoulder, a snap ring system, a visual indication, or other means.

For example, the axial move of the tail piperelative to the structureis stopped by the use of a flangeon the tail pipeengaging a landing shoulderarranged in the relative lower end of the guide, as best illustrated in. When the flangeengages the shoulder, it can be determined that the end position has been reached. In another example, the tail pipeincludes a snap ring that is flexible so that it can snap into a groove on the guide, or the other way around. When the snap ring snaps into the groove, it can be determined that the end position of the tail pipehas been reached. In another example, the means for determining an end position is a visual indicator, such as a scale, or a meter, that shows how much of the tail pipehas been lowered relative to the guide. Such a scale or a meter can indicate and determine that the end position of the tail pipehas been reached.

As illustrated by, for an embodiment of the method for providing a subsea template system with a tail pipe, the guidecomprises a first guidefor the tail pipe, and a second guidefor the conductor casing. In embodiments, the outer conductor casingis a conductoror a conductor housing. In embodiments, the method further comprises rotating and moving axially the tail piperelative to the guidewhile guiding the tail pipewith the first guide, and installing the outer conductor casingwhile guiding the conductor casingwith the second guide. In one embodiment, the guiding of the tail pipeis done with only the first guide, and the guiding of the conductor casingis done with only the second guide. By providing and guiding the tail pipeusing the first guide, and providing and guiding the outer conductor casingusing the second guide, it is possible to accurately and efficiently install the tail pipeand the conductor, the outer conductor casing, into the seabed.

With reference to, a subsea template system is disclosed. The subsea template system comprises a structureand a tail pipe. The structurecomprises a guide, the guidecomprising an openingfor a well. The structurecomprises a plurality of supportsfor engaging a seabed. The tail pipeis substantially cylindrical and comprises a serrated end structureat a first end, a first lower end, of the tail pipe. The tail pipeis arranged in the openingof the guide. The tail pipecomprises an interfacefor rotating and axially move the tail piperelative to the structure. The guidecomprises a first guidefor the tail pipe; a second guidefor an outer conductor casing; and means for determining an end position for the tail pipe.

According to one embodiment, the structurecomprises one, two, three, or four supportsfor engaging the seabed. In embodiments, the structureincludes the guidein a central position where the well is going to be, and the structurecomprises radial arms such that each arm stretches from the guidesubstantially parallel to the seabed, in a horizontal direction, to one support. In embodiments, the guideis a hollow cylinder into which the tail pipeand other piping, such as the outer conductor casing, may be guided. In embodiments, the guideis arranged, in some instances in a solid manner, in the central position of the structure, perpendicular to the radial arms, opening up towards the well. In embodiments, the structurecomprises a plurality of guide rod receptacles. In one embodiment, the receptacles are used for installing guide rods onto the structure. In another embodiment, the guide rods are used for installing a blow out preventer, BOP, onto the wellhead. In embodiments, the guide rods are attached to the structureby being inserted and locked into the receptacles. According to one embodiment, the tail pipeis a hollow cylinder, a metal cylinder, with a serrated end structure. In embodiments, the serrated end structureare teeth, cutting formations, that assist the tail pipeto cut its way into the seabed. This allows the tail pipe to cut through even a hard seabed. In some embodiments, the tail pipeis used initially before starting to drill the well. The tail pipeherein described is not a tail pipe under a production packer. The tail pipeis inserted into the ground to remain in the ground during the lifetime of the well, and thereafter if desired. In embodiments, the tail pipeis several meters long, for example over 6 meters long. In some embodiments, once the tail pipeis installed, an opening is drilled into the seabed inside the tail pipe, and subsequently a conductor, an outer conductor casing, is installed inside the tail pipe. In embodiments, the conductoris cemented in place by injecting cement between the inside of the tail pipeand the outside of the outer conductor casing. This reduces the amount of cement or drill cuttings that may escape into the environment.

As may be taken best from, in some embodiments, the first guideis separate from the second guide. In embodiments, the guides are hollow cylinders. In embodiments, the first guide, for the tail pipe, comprises two guides: one guidearranged in the upper part of the guide, and one guidearranged in the lower part of the guide. In embodiments, the landing shoulderoperates and functions as the guidein the lower part of the guide. In embodiments, the one guidearranged in the upper part of the guideis removably arranged on the guide. This allows the upper guide to be used for guiding the tail pipe, then be removed so that an outer conductor casing may use a second guidewith a larger diameter. In embodiments, the second guide, for the outer conductor casing, comprises two guides: one guidearranged in the upper part of the guideand one guidearranged in the lower part of the guide. This arrangement is advantageous as it allows the guideto guide the tail pipeand the outer conductor casingin one and the same guide. In embodiments, the guideis a well slot.

With reference to, and according to an embodiment, the tail pipefurther comprises a stoprestricting axial movement of the tail piperelative to the structure. In embodiments, the stopcomprises a flangeon the tail pipefor engaging a landing shoulderarranged in the relative lower end of the guide. In embodiments, the flangeis at the top endof the tail pipe. In embodiments, the landing shoulderis at the lower end of the guide. In embodiments, the flangeis an integral part of the tail pipe. In embodiments, the landing shoulderis an integral part of the guide. In embodiments, the stopgives the end position for the tail pipe, and this end position is below the outer conductor casinginteraction surfaces with the guide, that is below the lower guideon the guide.

With reference to, and according to an embodiment, the tail pipefurther comprises a stoprestricting axial movement of the tail piperelative to the structure. In embodiments, the stopcomprises a snap ring interacting with a groove. This alternative is not illustrated in the drawings. In embodiments, the snap ring is arranged on the tail pipeand the groove is arranged in the lower part of the guide, or opposite. In embodiments, the groove gives the end position for the tail pipe, and this end position is below the outer conductor casinginteraction surfaces with the guide, that is below the lower guideon the guide.

With reference to, and according to an embodiment, the interfaceis connectable to a drill string. In embodiments, the interfaceis part of the tail pipeand allows the drill stringto connect to the tail pipe. The drill stringmay then rotate and axially push the tail pipeinto the seabed. In embodiments, the interfaceis an adapter mounted onto the tail pipe. In embodiments, the interfaceis means for connecting, interfacing, with the drill string. In embodiments, the interfaceconnects to the drill stringvia a dedicated tool for this purpose on the drill string, or via a standard tool, such as a drill tool, that is connected to the drill string.

With reference to, and according to an embodiment, the interfaceis connectable to a drive systemon the structure. In embodiments, the drive systemis configured for rotating and moving axially the tail pipeinto the seabed.

With reference to, and according to an embodiment, the subsea template system further comprises a temporary lockfor locking the tail piperelative to the guide. This temporary lockis used when placingthe structureand the tail pipeonto the seabed. During the placing, the temporary lockis locked so that the tail pipeis held firmly by the guide. Once placed, the temporary lockmay be unlocked so that the tail pipecan be further moved into the seabed. The locked position is illustrated in, wherein the first lower endis closer to the guidethan the second higher endof the tail pipe.

According to one embodiment, a further separate lock is used to lock the tail piperelative to the guideonce the tail pipehas been installed. The lock prevents the tail pipefrom rotating during drilling and also prevents axial movement of the tail pipe.

With reference to, and according to an embodiment, the means for determining an end position for the tail pipemay be a shoulder, a snap ring system, a visual indication, or other means. For example, in an embodiment, the guidehas a shoulderand the tail pipea flangefor engaging the shoulder, as best illustrated in. When the flangeengages the shoulder, it can be determined that the end position has been reached. In another example, in an embodiment, the tail pipehas a snap ring that is flexible so that it can snap into a groove on the guide, or the other way around. When the snap ring snaps into the groove, it can be determined that the end position of the tail pipehas been reached. In another example, in an embodiment, the means for determining an end position is a visual indicator, such as a scale, or a meter, showing how much of the tail pipehas been lowered relative to the guide. Such a scale or a meter can indicate and determine that the end position of the tail pipehas been reached.

With reference to, and according to an embodiment, the first guidefor the tail pipeis removable; and/or the first guidefor the tail pipehas a smaller inner diameter than the second guidefor the outer conductor casing. In an embodiment, the upper first guidemay be removed from the guideonce the tail pipehas been installed. In combination with this, or as an alternative, in an embodiment, the first guidefor the tail pipehas a first inner diameter that contacts and guides the tail pipe. In embodiments, the second guidefor the outer conductor casinghas a second inner diameter that contacts and guides the outer conductor casing. In embodiments, the first inner diameter is larger than the second inner diameter.

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.