Modular drilling rigs have been used in the oil and gas industry, both in offshore drilling industry and on land for a considerable time. An early example of such a modular drilling rig is described in US 3,228,151. In this document a drilling apparatus is disclosed comprising a base substructure having a base, an elevatable drilling floor and means between them for raising the floor, preferable hingable legs. A mast is provided, having rear legs extending upward from the substructure and front legs extending downward in front of the substructure, pivotal means supporting the front legs. The mast is swingable on said pivotal means.

Improvements to modular drilling rigs have been described by the same applicant in

WO2013133699, WO2013133698, WO2014178712. It is an aim of the invention to provide a more efficient modular drilling rig system.

From US2004/021 1598 a method and apparatus for transporting and assembling a drilling rig is disclosed. The lower section is transported via a trailer to the drill site with a top drive already installed within the lower section. At the drill site, the trailer is brought into alignment with a bottom section.

From US2012/167485 a high-capacity drilling rig system is known comprising a transport trailer having a first support member and a drive member which align the lower mast portion with inclined rig floor ramps and translate the lower mast legs up the ramps and into alignment for connection.

A first aspect of the invention relates to a modular transfigurable drilling rig system composed of multiple components, which system is transfigurable between a transport mode in which the components of the system are transportable by vehicles and an operational mode in which the components are assembled to a drilling rig which is adapted to perform drilling and/or wellbore related activities, e.g. drill into a well centre in the ground, the drilling rig system comprising:

- a base structure adapted to be positioned in the operational mode on the ground; - a drilling rig mast having a top end and a foot end, composed of multiple transportable mast sections, said mast sections at least including a lower mast section comprising the foot end of the mast, the lower section being connectable to the base structure, and a top mast section comprising the top end of the mast, and preferably one or more intermediate mast sections, wherein preferably mast sections have a U-shaped horizontal cross section with a left-hand mast wall, a rear mast wall, and a right-hand mast wall, and with an open front, wherein preferably mast sections are provided with one or more vertical rails adapted to guide a top drive unit, which drilling rig mast is movable between a substantially horizontal mast assembly position, wherein the mast is assembled by interconnection of said multiple mast sections in generally horizontal orientation and, in the operational mode, a vertical operational position, e.g. vertically above a well center;

- a top drive unit adapted to be positioned in the drilling rig mast so as to perform drilling activities and advantageously be guided by said one or more vertical rails allowing for vertical motion of the top drive unit relative to the mast.

The top drive unit is an expensive and complex piece of machinery that requires careful handling. Also the actual top drive unit suitable for a particular drilling activity may vary from one suitable for another drilling activity.

It is therefore desirable to provide a modular transfigurable drilling rig system that allows for easy and careful handling and/or exchange of the top drive unit.

The invention proposes a transfigurable drilling rig system wherein the drilling rig system further comprises a temporary removable vehicle transportable top drive unit installation device that comprises a frame that is adapted to receive the top drive unit so as to transport the installation device with the top drive unit therein by a vehicle,

wherein the frame of the installation device is positionable in line with an end of a mast section of the mast in said substantially horizontal mast assembly position, e.g. of an intermediate mast section of the mast prior to assembly of the top mast section, wherein, for example, the frame is provided with one or more alignment and/or connection members, e.g. hooks, to align and/or connect the frame with the respective mast section, so as to be able to transfer the top drive unit from the frame of vehicle transportable top drive unit installation device (130) into the drilling rig mast in the substantially horizontal mast assembly position thereof, prior to removal of the vehicle transportable top drive unit installation device. Hereafter, the drilling rig mast with the top drive is allowed to move towards its vertical operational position. In embodiments, the temporary removable installation device comprises a top drive unit translation assembly with a translation drive to transfer, e.g. slide, the top drive unit from the frame of the installation device into the drilling rig mast in the substantially horizontal mast assembly position thereof. Alternatively, a separate translation drive is provided. Advantageously, the translation drive comprises a winch and a winch driven cable connectable to the top drive unit and adapted to transfer, e.g. slide, the top drive unit into the mast in its substantially horizontal assembly position. Alternative drive include a cylinder, chain drive etc. etc. In embodiments, the frame comprises one or more rails that are aligned with said one or more rails of the mast when the frame of the installation device is positioned in line with an end of a mast section of the mast in said substantially horizontal mast assembly position, and wherein the top drive unit comprises one or more rail followers that are engaged with the one or more rails of the frame prior to said transfer into the mast and then are engaged with said one or more rails of the mast upon transfer into the mast. This ensures a proper alignment and safe transfer of the delicate equipment.

In embodiments, the mast is adapted to be - in its substantially horizontal assembly position - with its open front facing down, e.g. said open front at a height of less than 1 metre above the ground.

In embodiments, the mast sections comprise left-hand and right-hand vertical front posts and rear corner posts, with each front post being connected by bracings to a respective rear corner post to form the respective side wall of the mast and said rear corner posts being connected to each other by bracings to form the respective rear wall of the mast, and wherein, preferably, a vertical rails is fixed to each of the front posts and the top drive unit is guided along said vertical rails. Such a construction is extremely solid and safe.

In embodiments, the top mast section comprises a crown block assembly with cable sheaves mounted to the top mast section and a travelling block assembly with cable sheaves, wherein, preferably, one or more cables are pre-reeved over said crown block and travelling block assembly. Such pre-reeving increases the on-site efficiency. In embodiments, the drilling rig system further comprises at least one drive assembly to move the drilling rig mast with the top drive between the substantially horizontal mast assembly position and the vertical operational position. Alternatively, a separate drive is provided to erect the drilling rig mast.

In embodiments, an intermediate mast section of the mast comprises a drag chain with one or more electrical and/or hydraulic lines connectable to the top drive unit.

The invention also provides a method for bringing the modular transfigurable drilling rig system into operational mode comprising:

placing the base structure on the ground,

positioning the lower mast section in a generally horizontal position thereof such that the foot end of the lower mast section is brought adjacent the base structure;

connecting the foot end of the lower mast section to the base structure;

- positioning one or more further drilling rig mast sections in substantially horizontal position thereof in line with the lower mast section and interconnecting said mast sections;

wherein the method further comprises:

positioning the vehicle transportable top drive unit installation device in line with the end of a mast section of the mast in said substantially horizontal mast assembly position, e.g. of an intermediate mast section of the mast prior to assembly of the top mast section,

- transferring, e.g. sliding, the top drive unit from the frame of the installation device into the drilling rig mast in the substantially horizontal mast assembly position thereof;

removing the frame of the temporary removable vehicle transportable top drive unit installation device, prior to moving the drilling rig mast with the top drive unit towards its vertical operational position.

In embodiments, the installation device comprises a top drive unit translation assembly with a translation drive to transfer, e.g. slide, the top drive unit from the frame of the installation device into the drilling rig mast in the substantially horizontal mast assembly position thereof. In such embodiments, a possible method of the invention further comprises the step of operating the translation drive of the top drive unit translation assembly to transfer, e.g. slide, the top drive unit from the frame of the installation device into the drilling rig mast in the substantially horizontal mast assembly position thereof. In embodiments, the translation drive comprises a winch and a winch driven cable connectable to the top drive unit. In a possible method of the invention the winch is operated to transfer, e.g. slide, the top drive unit into the mast in its substantially horizontal assembly position. In embodiments, the frame comprises one or more rails that are aligned with said one or more rails of the mast when the frame of the installation device is positioned in line with an end of a mast section of the mast in said substantially horizontal mast assembly position, and wherein the top drive unit comprises one or more rail followers that are engaged with the one or more rails of the frame prior to said transfer into the mast and then are engaged with said one or more rails of the mast upon transfer into the mast.

In embodiments, the mast is assembled - in its substantially horizontal assembly position - with its open front facing down, e.g. said open front at a height of less than 1 metre above the ground.

In embodiments, the top drive unit installation device is offloaded from a road vehicle and positioned in line with and connected to the respective mast section, and wherein the top drive unit is subsequently transferred into the mast.

In embodiments, the temporary removable vehicle transportable top drive unit installation device is positioned in line with the end of an intermediate mast section of the mast in said substantially horizontal mast assembly position, and wherein the top drive unit is then transferred into said intermediate mast section, and wherein the frame of the installation device is then removed, and wherein subsequently the top mast section is positioned in line with the already assembled part of the mast and connected thereto.

In embodiments, the top mast section comprises a crown block assembly with cable sheaves mounted to the top mast section and a travelling block assembly with cable sheaves, wherein, preferably, one or more cables are pre-reeved over said crown block and travelling block assembly. Advantageously, the method comprises the step of connecting the travelling block assembly to the top drive unit that has been transferred into an adjoining intermediate mast section, e.g. wherein the travelling block assembly comprises a hook that is engageable with the top drive unit.

It will be appreciated that the first aspect of the invention can be readily combined with one or more of the other aspects of the disclosure as described herein and/or with one or more optional and/or preferred features as described herein primarily with reference to said one or more other aspects of the disclosure.

According to a second aspect of the invention this is achieved in that the modular transfigurable drilling rig system composed of multiple components, which system is transfigurable between a field transport mode in which components of the system are transportable on the field by vehicles between multiple well centers, and an operational mode in which the components are assembled into a drilling rig which is adapted to drill into a well centre in the ground of the field, the system comprising:

a drilling rig mast having a top end and a foot end, which is movable between a substantially horizontal mast assembly position and an operational position substantially vertically above the well centre, the drilling rig mast including:

o a lower section, comprising the foot end of the mast, the lower section being

connectable to a base structure, and

o a top section, comprising the top end of the mast and a top drive,

at least one drive assembly to move the drilling rig mast with the top drive between the substantially horizontal mast assembly position and the vertical operational position, a base structure adapted to be positioned in the operational mode in a H-shape on the surface adjacent a well centre to support the drilling rig mast thereon, which base structure is adapted to be transported by a vehicle, the H-shaped base structure comprising an assembly of interconnected parts, including:

o a first set of support beams adapted to be positioned on the surface with the well center there between, the first set of beams extending in a first direction, which support beams are adapted to accommodate transport wheels, at least in the field transport mode; and

o a second set of support beams adapted to be placed on the surface and extending in a second direction opposite to the first direction,

- transport wheels, adapted to be accommodated by the first set of support beams,

a transport connection assembly which is adapted to in the field transport mode be provided between the vehicle and the second set of support beams in order to transport the base structure as a whole.

The provision of transport wheels and a transport connection assembly facilitates within field movements of the modular transfigurable drilling rig system. Within field moves are e.g.

advantageous when the system is applied for fracking. For example with fracking, on a field, also known as well pad or pad, multiple wells, for example ten wells or more, are drilled relative close to each other. The invention facilitates transport of the transfigurable drilling rig system on the field, for example from one well center to another well center, with the transfigurable drilling rig system in its field transport mode.

It is noted that transport of drilling rig systems between fields, or well pads, often requires transport over public roads, which brings with it stringent dimensional constraints regarding the configuration of the drilling rig. Typically, a modular drilling rig is configured such that it can be transfigured into a transport mode, which transport mode enables on field transport and also allows for transport between fields or pads. The on field transport mode according to the invention provides a third configuration, which allows for transportation of the drill rig between wells but does not require full disassembly into the transport mode, it therefore reduces down time in case of on field transport between well centres compared to on field transport between well centres using the transport mode.

In embodiments, the H-shaped base structure is obtained by a cross part which is an integral part of one or both of the first set of support beams, and/ or one or both of the second set of support beams. For example, the cross part is formed as an integral part of a support beam, such that the support beam is "L-shaped" when seen from above. Together with the other support beams, the base structure is formed in a H-shape. It is also conceivable that two support beams comprise a protruding part extending perpendicular to the first or second direction, such that the cross part is formed by both protruding parts.

In particular embodiments, the transportable base structure further comprises a cross beam adapted to be positioned on the ground near the well centre, to which at least one of the first and/or second set of support beams is connected in the operational mode.

In embodiments, the cross beam being of a foldable design, allowing the cross beam to be folded out in the operational mode and folded in in the field transport mode such that the mutual distance between the support beams is reduced. Hence, the 'legs' of the H-shaped base structure are movable towards each other to decrease the width of the Ή'. This is advantageous if the H-shaped base structure is too wide to be transported as a whole.

In embodiments, the lower section of the drilling rig mast further comprises drilling drawworks. Alternatively, the drawworks are positioned on the surface adjacent the drilling rig mast, and are separately transported. As the drilling drawworks is a voluminous and heavy-weight component, it is common to transport the drilling drawworks seperately from the lower section.

In embodiments, the lower section of the drilling rig mast further comprises a pedestal, adapted to support the drilling rig mast above the well centre in the operational mode. Such a pedestal imposes a distance between the well centre and the drilling rig mast, which is e.g. suitable to receive a BOP.

In embodiments, the transportable base structure is furthermore provided with a skid system to fine tune the position of the base structure adjacent a well centre. Such a skid system, as is known per se in the art, may e.g. be provided at the outer ends of the support beams of the H- shaped base structure. In embodiments, the transport connection assembly comprises a transport beam, which is connectable to the outer ends of the second set of support beams and which preferably comprises a king pin to be connected to a fifth wheel of the vehicle. The connection to the king pin enables steering movement of the base structure.

The second aspect of the invention further relates to a method for bringing a modular transfigurable drilling rig system according to one or more of the preceding claims from a field transport mode into an operational mode. In embodiments, the method comprises the steps of:

positioning the transportable base structure on the ground adjacent the well centre, disconnecting the second set of support beams from the transport connection assembly, removing the transport vehicle,

positioning the lower section in a substantially horizontal position so that the foot end of the mast is brought adjacent the base structure;

connecting the lower section to the base structure;

positioning the top section in a substantially horizontal position adjacent the lower section;

aligning and connecting the upper end of the lower section with a lower end of the top section;

operating the at least one drive assembly such that the drilling rig mast with the top drive moves towards its vertical operational position.

It is noted that the top section of the drilling rig mast is the section that, when the drilling rig is operational, is located on top of and vertically above the lower section of the drilling rig mast.

During road transport the top section and the lower section of the drilling rig mast are typically in a horizontal position, i.e. do not extend in a vertical direction but in a substantially horizontal direction. In operational mode, the location of the transfigurable drilling rig system as a whole is fixed, even though the system may allow for fine tuning of parts of the system relative to the well center. When in the field transport mode, the location of the transfigurable drilling rig can be changed using the transport wheels and the transport connection system in combination with a vehicle.

As discussed above, in embodiments the transportable base structure further comprises a cross beam adapted to be positioned on the ground near the well centre, to which at least one set of support beams is connected in the operational mode. Advantageously, the cross beam is of a foldable design, allowing the cross beam to be folded out in the operational mode and folded in in the field transport mode such that the mutual distance between the support beams is reduced. In such embodiments, the method further comprises the step of folding out the cross beam, thereby increasing the mutual distance between the support beams.

Optionally, the method further comprises the step of removing the transport wheels from the first set of support beams. Alternatively, it is also conceivable that the transport wheels remain accommodated by the first set of support beams. Optionally, the method further comprises the step of removing the transport connection assembly from the transport vehicle. It is also conceivable that the transport connection assembly remains attached to the transport vehicle, to be ready for a further transport of the modular drilling rig system. A third aspect of the invention relates to a modular transfigurable drilling rig composed of multiple components, which system is transfigurable between a transport mode in which the components of the system are transportable by vehicles and an operational mode in which the components are assembled to a drilling rig which is adapted to perform drilling and/or wellbore related activities, e.g. drill into a well centre in the ground, the drilling rig system comprising: - a base structure adapted to be positioned in the operational mode on the ground;

a drilling rig mast having a top end and a foot end, composed of multiple transportable mast sections, said mast sections at least including a lower section comprising the foot end of the mast, the lower section being connectable to the base structure, and a top (crown) section comprising the top end of the mas;

- which drilling rig mast is movable between a substantially horizontal mast assembly position, wherein the mast is assembled by interconnection of said multiple mast sections in generally horizontal orientation and, in the operational mode, a vertical operational position; and drilling drawworks adapted to be mounted to the lower section of the drilling rig mast in order to, in the operational mode, perform hoisting activities.

The drilling drawworks is an expensive and heavy piece of machinery, that is usually positioned on the ground adjacent the drilling rig system.

It is therefor desirable to provide a modular transfigurable drilling rig system that allows for the installation of drilling drawworks remote from the ground.

The invention proposes a transfigurable drilling rig system comprising a vehicle transportable drilling drawworks ramp adapted to install the drawworks, the drilling drawworks ramp comprising a sliding surface allowing the drilling drawworks to slide over to the lower section of the drilling rig mast in the horizontal position,

wherein the sliding surface of the drilling drawworks ramp is positionable adjacent a lower section of the mast in said substantially horizontal mast assembly position.

In embodiments is the drilling drawworks ramp provided with one or more alignment and/or connection members, e.g. hooks, to align and/or connect the drilling drawworks ramp with the lower mast section. The thus achieved clearance of the ground in the drilling area is very advantageous during drilling operations and enables a more efficient drilling process.

In embodiments, the drilling drawworks ramp further comprises a drilling drawworks positioning assembly with a drive to slide the drilling drawworks over the sliding surface and position the drilling drawworks onto the lower section of the drilling rig mast. Alternatively, such a drive is separately provided.

In embodiments, the drilling drawworks positioning assembly comprises a winch driven cable connectable to the drilling drawworks and adapted to slide the drilling drawworks over the drilling drawworks ramp to install the drawworks. Alternative drive include cylinders, chain drives, etc. etc.

In embodiments, the drilling rig system further comprises a drawworks subframe, which is adapted to be mounted onto the lower mast section, and onto which the drilling drawworks are adapted to be mounted in the substantially horizontal mast assembly position. Such a subframe may facilitate on-site mounting. For example, upon displacement of the drilling rig system on the field between multiple well centres, it is conceivable that the drawworks subframe remains mounted to the lower mast section such that the drilling drawworks can conveniently be mounted to the drilling drawworks subframe after the displacement.

In embodiments, the drilling rig system further comprises at least one drive assembly to move the drilling rig mast with the drilling drawworks between the substantially horizontal mast assembly position and the vertical operational position. In embodiments, the drilling rig mast comprises a lower section, a top section and one or more intermediate mast sections. Preferably mast sections have a U-shaped horizontal cross section with a left-hand mast wall, a rear mast wall, and a right-hand mast wall, and with an open front. The invention also relates to a method for bringing a modular transfigurable drilling rig system composed of multiple components from a transport mode in which the components of the system are transportable by vehicles into an operational mode in which the components are assembled to a drilling rig which is adapted to perform drilling and/or wellbore related activities, e.g. drill into a well centre in the ground, the drilling rig system comprising:

a base structure adapted to be positioned in the operational mode on the ground;

a drilling rig mast having a top end and a foot end, composed of multiple transportable mast sections, said mast sections at least including a lower section comprising the foot end of the mast, the lower section being connectable to the base structure, and a top (crown) section comprising the top end of the mast;

- which drilling rig mast is movable between a substantially horizontal mast assembly position, wherein the mast is assembled by interconnection of said multiple mast sections in generally horizontal orientation and, in the operational mode, a vertical operational position, e.g.

vertically above a well center; and

- drilling drawworks adapted to be mounted to the lower section of the drilling rig mast in order to, in the operational mode, perform hoisting activities;

wherein the method comprises the steps of:

positioning the base structure on the ground adjacent the well centre,

positioning the lower mast section so that the foot end of the lower mast section is brought adjacent the base structure;

connecting the foot end of the lower mast section to the base structure;

supplying the drilling drawworks;

positioning and mounting the drilling drawworks onto the lower section of the drilling mast prior to moving the drilling rig mast with the drilling drawworks moves towards its vertical operational position.

The invention further relates to a method for bringing a modular transfigurable drilling rig system from a transport mode into an operational mode, wherein the method comprises the steps of: positioning the base structure on the ground adjacent the well centre,

- positioning the lower mast section so that the foot end of the lower mast section is brought adjacent the base structure;

connecting the foot end of the lower mast section to the base structure;

supplying the drilling drawworks ramp, preferably by a vehicle, and positioning the drilling drawworks ramp adjacent the lower section,

- supplying, preferably by means of a vehicle, the drilling drawworks to the drilling drawworks ramp;

sliding the drilling drawworks over the sliding surface to the lower section of the drilling mast; mounting the drilling drawworks to the lower section; removing the drilling drawworks ramp.

In embodiments, the method further comprises the step of installing a drawworks subframe onto the substantially horizontal lower mast section, prior to the positioning and mounting of the drilling drawworks.

It will be appreciated that all aspects of the invention can be readily combined with one or more of the other aspects of the invention as described herein and/or with one or more optional and/or preferred features as described herein primarily with reference to said one or more other aspects of the invention.

For example, in an embodiment according to the invention, the vehicle transportable top drive unit installation device of the first aspect of the invention is configured as a drilling drawworks ramp according to the third aspect of the invention, such that the top drive unit installation device can also be used for installing the drawworks onto the lower section of the drilling rig mast and vice versa.

The invention is further described in the claims and explained here below in relation to the drawings, in which:

Figs. 1A,1 B, 1C show in top view the base structure of a modular transfigurable drilling rig system transported by a vehicle according to a second aspect of the present invention in the field transport mode, and the vehicle without the base structure;

Figs 2A, 2B show in side view the base structure and lower section a modular

transfigurable drilling rig according to the second aspect of the invention in the field transport mode;

Figs 3A, 3B, 3C show in side view the base structure and lower section a modular

transfigurable drilling rig according to the second aspect of the invention in the field transport mode;

Figs 4a - d illustrate the transfer of a top drive unit into the partly assembled mast of an exemplary modular transfigurable drilling rig system of the invention,

Figs 5a, 5b illustrate the completion of the mast of figures 4a-d with a top mast section, Figs 5c, d illustrate the hooking of the travelling block onto the top drive unit,

Figs 6A, 6B show in side view a drilling drawworks ramp according to a third aspect of the present invention,

Figs 7A, 7B, 7C show in side view the installation of drilling drawworks via a drilling

drawworks ramp according to a third aspect of the present invention, Figs. 8A, 8B show in different side views a lower mast section prior to be moved to the vertical operational position, onto which drilling drawworks are positioned.

In figs. 1-3 an embodiment of the invention is shown in the field transport mode in which components of the system are transportable on the field by vehicles between multiple well centers.

In particular, in figs. 1A-1 B the transport of the base structure by a vehicle is shown, in figs. 2A- 2B the transport of the lower section of the drilling rig mast and in figs. 3A-3C the transport of the top section of the drilling rig mast.

In fig. 1A, a base structure 20 is shown in top view, which is in fig. 1A positioned on the ground adjacent a well centre W, to support a drilling rig mast thereon. In fig. 1A, the base structure is transported by a vehicle 10. In fig. 1C the vehicle 10 is shown without the base structure.

The base structure 20 comprises a first set of support beams 23a, 23b, which are positioned on the ground with the well center W there between. The first set of beams 23a, 23b extend in a first direction D1. In the shown field transport mode, the support beams 23a, 23b accommodate transport wheels 25a, 25 respectively. The transport wheels 25a, 25b are possibly removed in the operational mode. However, it is also conceivable that the wheels remain connected to the support beams for further within field movements.

The base structure further comprises a second set of support beams 22a, 22b, placed on the ground and extending in a second direction D2 opposite to the first direction D1 , such that the base structure 20 is formed in a H shape in the transport mode shown in fig. 1A and in the operational mode.

In the shown field transport mode of figs. 1A and 1 B, a transport connection assembly 15 is provided between the vehicle 10 and the second set of support beams 22a, 22b in order to transport the base structure 20 as a whole.

In the shown embodiment, the transport connection assembly 15 comprises a transport beam, which is in figs. 1A and 1 B connected to the outer ends of the second set of support beams 22a, 22b and to a king pin 11 of the vehicle 10. In fig. 1C, it is visible that the transport beam 15 is connected to the vehicle 10. Optionally, the transport beam is removed, but it is also

conceivable that the transport beam remains connected to the vehicle for further within field moves. ln the shown embodiment, the transportable base structure 20 in the operational mode further comprises a cross beam 21 adapted to be positioned on the ground near the well centre W. In the shown embodiment, the second set of support beams 22a, 22b is connected to the cross beam. The first set of support beams 23a, 23b is connected to the second set of support beams. It is also conceivable that only the first set of support beams is connected to the cross beam 21 , and the second set of support beams is connected to the first set. Yet alternatively, it is conceivable that both the first and the second set of support beams are connected to opposed sides of the cross beam. It is conceivable that the base structure 20 is transportable as a whole with the cross beam and connected support beams in the H-shape as shown in fig. 1 B. However, possibly a decreased width is required. To this end, advantageously the cross beam 21 is of a foldable design, allowing the cross beam to be folded out in the operational mode (as visible in fig. 1 B) and folded in in the field transport mode (as visible in fig. 1 A) such that the mutual distance between the support beams (22a and 22b, and 23a and 23b respectively) is reduced.

In the shown embodiment, the transportable base structure 20, in particular the first set of support beams 23a, 23b, is furthermore provided with a skid system 24a, 24b to fine tune the position of the base structure 20 adjacent a well centre W.

In fig. 2A, the base structure 20 is shown in a side view, with the transport vehicle removed. The base structure is provided with a drilling rig mast receptacle 26 to allow the connection of the drilling rig mast to the base structure. In the shown embodiment, the drilling rig mast receptacle is provided on the cross beam 21.

At the right-hand side of fig. 2A, a vehicle 30 with a lower section 40 of the drilling rig mast is shown. The lower section 40 comprises a foot end 41 of the drilling rig mast. In the shown embodiment, the lower section 40 further comprises drilling drawworks 42. In the shown embodiment, the lower section 40 further comprises a pedestal 43, adapted to support the drilling rig mast above the well centre in the operational mode.

In fig. 2B, the lower section has been positioned in a substantially horizontal position adjacent the base structure, allowing the connection of the lower section 40, in particular a connection hole 43a provided at the outer end of the pedestal 43, to the drilling rig mast receptacle 26 to the base structure 20.

In fig. 3A, a drive assembly 45 is connected to the lower section 40 of the drilling rig mast. In the shown embodiment, the drive assembly 45 comprises two hydraulic cylinders, mounted between the second set of support beams 22a, 22b of the base structure 20 and the pedestal 43 at the foot end 41 of the mast. In fig. 3A, the drive assembly 45 has moved the lower section upwards. In fig. 3B, a transport vehicle 30 with a top section 50 of the drilling rig mast is shown, which is positioned in a substantially horizontal position adjacent the lower section 40. The top section 50 comprises the top end of the mast 51 and a top drive 52. In fig. 3C, the alignment and connection of the upper end of the lower section 40 with a lower end of the top section 50 is visible.

From the position of fig. 3C, the drive assembly 45 may be operated to move the drilling rig mast with the top drive 52 between the substantially horizontal mast assembly position, as visible in fig. 3C, and a vertical operational position. In figures 4a - d the transfer of a top drive unit into the partly assembled mast of an exemplary modular transfigurable drilling rig system of the invention is illustrated.

Generally the drilling rig system according to the invention is composed of multiple components, and the system is transfigurable between a transport mode in which the components of the system are transportable by vehicles and an operational mode in which the components are assembled to a drilling rig which is adapted to perform drilling and/or wellbore related activities, e.g. drill into a well centre in the ground.

The drilling rig system comprises a base structure 100 that is adapted to be positioned in the operational mode on the ground, for example the base structure is embodied as described with reference to figures 1 - 3;

The drilling rig system comprises a drilling rig mast 110 having a top end and a foot end. The mast 110 is composed of multiple transportable mast sections, including a lower mast section 111 comprising the foot end of the mast, the lower section being connectable to the base structure, and a top mast section 113 comprising the top end of the mast. Here the mast also comprises an intermediate mast section 112. The mast sections 111 , 1 12, 1 13 have a U-shaped horizontal cross section with a left-hand mast wall, a rear mast wall, and a right-hand mast wall, and with an open front that is facing downwards in the illustrations of figures 4a-d. The open front end allows for the introduction of drilling tubulars, e.g. drill pipes, into the mast in the firing line below the top drive unit. The mast sections 11 1 , 112, 113, are provided with one or more vertical rails 114 adapted to guide a top drive unit 120. In more detail the mast sections 111 , 112, 113 comprise left-hand and right-hand vertical front posts and rear corner posts, with each front post being connected by bracings to a respective rear corner post to form the respective side wall of the mast and said rear corner posts being connected to each other by bracings to form the respective rear wall of the mast. A vertical rails 114 is fixed to each of the front posts and the top drive unit 120 is guided along said vertical rails 1 14. Other arrangements of one or more vertical rails in the mast sections are also envisaged.

The drilling rig mast, once assembled, is movable between the substantially horizontal mast assembly position, wherein the mast is assembled by interconnection of said multiple mast sections in generally horizontal orientation and, in the operational mode, a vertical operational position, e.g. vertically above a well center.

The top drive unit 120 is adapted to be positioned in the drilling rig mast 110 so as to be guided by said one or more vertical rails 114 allowing for vertical motion of the top drive unit relative to the mast to perform drilling activities.

The drilling rig system further comprises a vehicle transportable top drive unit installation device 130 that comprises a frame 135 that is adapted to receive the top drive unit 120 so as to transport the installation device with the top drive unit therein by a vehicle 150.

The frame 135 of the installation device 130 is positionable in line with an end of a mast section of the mast in said substantially horizontal mast assembly position, here the intermediate mast section 112 of the mast prior to assembly of the top mast section 113.

In this example the frame 135 is provided with one or more alignment and/or connection members, here hooks 136, to align and/or connect the frame with the respective mast section 111. The installation device 130 further, as preferred feature, comprises a top drive unit translation assembly with a translation drive to transfer, e.g. slide, the top drive unit 120 from the frame of the installation device into the drilling rig mast in the substantially horizontal mast assembly position thereof, e.g. with one or more rail followers 122 of the top drive unit 120 being engaged with said one or more rails 114 of the mast.

In this example the frame 135 comprises one or more rails (not shown) that are aligned with said one or more rails 114 of the mast when the frame 135 of the installation device is positioned in line with an end of a mast section 111 of the mast in said substantially horizontal mast assembly position.

The rail followers that are engaged with the one or more rails of the frame prior to said transfer into the mast are then engaged with said one or more rails 114 of the mast upon transfer into the mast.

In this example, the translation drive comprises a winch 137 and a winch driven cable 138 connectable to the top drive unit 120 and adapted to transfer, e.g. slide, the top drive unit into the mast in its substantially horizontal assembly position.

As can be seen the mast is facing - in its substantially horizontal assembly position - with its open front facing down, e.g. said open front at a height of less than 1 metre above the ground, so generally below the bed of the vehicle 150.

The top mast section 113 comprises a crown block assembly 115 with cable sheaves mounted to the top mast section and a travelling block assembly 116 with cable sheaves. As preferred, one or more cables 117 are pre-reeved over said crown block and travelling block assemblies. The intermediate mast section 1 12 of the mast comprises a drag chain 112a with one or more electrical and/or hydraulic lines connectable to the top drive unit 120.

As the skilled person will already appreciate from the illustrations in figures 4a -d, 5a, 5b, the method for bringing the modular transfigurable drilling rig system into operational mode involves inter alia the steps of:

- placing the base structure 100 on the ground,

- positioning the lower mast section 111 in generally horizontal position thereof such that the foot end of the lower mast section is brought adjacent the base structure;

- connecting the foot end of the lower mast section to the base structure;

- positioning the intermediate mast section 112 in substantially horizontal position thereof in line with the lower mast section 111 and interconnecting said mast sections.

The method further comprises the steps of: - positioning the vehicle transportable top drive unit installation device 130 in line with the end of the intermediate mast section 112 in said substantially horizontal mast assembly position,

- operating the translation drive, here winch 137, of the top drive unit translation assembly and transferring, here sliding, the top drive unit 120 from the frame 135 of the installation device into the drilling rig mast in the substantially horizontal mast assembly position thereof. Here with the one or more rail followers 122 of the top drive unit 120 engaging with said one or more rails 114 of the mast once they disengage from the one or more rails 136 of the frame 135. As illustrated it is preferred that the mast is assembled - in its substantially horizontal assembly position - with its open front facing down, here said open front at a height of less than 1 metre above the ground. It is also preferred to place the device 130 on the ground to effect the discussed transfer, which involves offloading the device 130 from the road vehicle 150, for example in the manner depicted in figures 4a, b. Other offloading approaches are also possible, however in the depicted approach the device (whilst resting on the vehicle bed) is connected to the mast end (e.g. the mast end being raised slightly) and then pulled from the vehicle bed.

So, it is illustrated here that the top drive unit installation device is offloaded from a road vehicle and positioned in line with and connected to the respective mast section, and the top drive unit is subsequently transferred into the mast.

It is illustrated that the vehicle transportable top drive unit installation device 130 is positioned in line with the end of an intermediate mast section 112 of the mast in said substantially horizontal mast assembly position, and that the top drive unit 120 is then transferred into said intermediate mast section 1 11. Then the frame 135 of the installation device is removed, and subsequently the top mast section 113 is positioned in line with the already assembled part of the mast and connected thereto as illustrated in figures 5a, b.

It is illustrated in figures 5c, d how the connection between the travelling block assembly 116 and the top drive unit 120 that has already been transferred into an adjoining intermediate mast section can be made. In this example the travelling block assembly comprises a hook 116a that is engageable with the top drive unit, e.g. by allowing the hooked end to tilt downward over a corresponding bail of the top drive unit. Once the mast is completely assembled the mast is raised or erected into its vertical operation position, e.g. by means of one or more hydraulic actuators 160 between the base structure and the mast or by some other means. ln figs. 6-8 the installation of drilling drawworks onto an at least partly assembled mast of an exemplary modular transfigurable drilling rig system of a third aspect of the invention is illustrated. Similar to the embodiment of figs. 4-5, the drilling rig system of the invention is composed of multiple components, and the system is transfigurable between a transport mode in which the components of the system are transportable by vehicles and an operational mode in which the components are assembled to a drilling rig which is adapted to perform drilling and/or wellbore related activities, e.g. drill into a well centre in the ground.

The drilling rig system comprises a base structure 210 adapted to be positioned in the operational mode on the ground, for example the base structure is embodied as described with reference to figs. 1-3 or 4-5. The drilling rig system further comprises a drilling rig mast having a top end (not shown) and a foot end. The mast is composed of multiple transportable mast sections, including a lower section 240 comprising the foot end of the mast, the lower section being connectable to the base structure. Possibly the mast is embodied as described with reference to figs. 4 and 5, further comprising a top (crown) section comprising the top end of the mast, and an

intermediate mast section.

The shown mast section 240 has a U-shaped horizontal cross section with a left-hand mast wall, a rear mast wall, and a right-hand mast wall, and with an open front. The drilling rig mast, once assembled, is movable between a substantially horizontal mast assembly position, wherein the mast is assembled by interconnection of said multiple mast sections in generally horizontal orientation and, in the operational mode, a vertical operational position, e.g. vertically above a well center. Drilling drawworks 242 are adapted to be mounted to the lower section 240 of the drilling rig mast in order to, in the operational mode, perform hoisting activities.

The drilling rig system further comprises a vehicle transportable drilling drawworks ramp 200 adapted to install the drawworks 242, the drilling drawworks ramp comprising a sliding surface 201 allowing the drilling drawworks to slide over to the lower section of the drilling rig mast in the horizontal position. The drilling drawworks ramp 200 of the shown embodiment is the same as the vehicle transportable top drive unit installation device 130 of figs. 4 and 5. The sliding surface of the drilling drawworks ramp is positionable adjacent a lower section of the mast in said substantially horizontal mast assembly position.

In this example, the drilling drawworks ramp 200 is provided with one or more alignment and/or connection members 208, e.g. hooks, to align and/or connect the drilling drawworks ramp with corresponding connection members 209 provided at the lower mast section 240.

The drilling drawworks ramp 200 further, as a preferred feature, comprises a drilling drawworks positioning assembly 202, 203 with a drive 205 to slide the drilling drawworks 242 over the sliding surface and position the drilling drawworks onto the lower section of the drilling rig mast.

In this example, the drilling drawworks positioning assembly comprises a winch 205 and a winch driven cable 202 connectable to the drilling drawworks and adapted to slide the drilling drawworks over the drilling drawworks ramp to install the drawworks. It is noted that where the same drilling drawworks ramp 200 is used as a top drive unit translation assembly, the same winch and winch driven cable may be applied.

In the shown embodiment, a drawworks subframe 245 is mounted onto the lower mast section 240. As visible in figs. 7a-7c, the drilling drawworks are adapted to be mounted onto the drawworks subframe 245 in the substantially horizontal mast assembly position.

In embodiments, not shown, further a drive assembly is provided to move the drilling rig mast with the drilling drawworks between the substantially horizontal mast assembly position and the vertical operational position.

As the skilled person will already appreciate from the illustrations in figs. 6-8, the method for bringing a modular transfigurable drilling rig system into an operational mode involves inter alia the steps of:

positioning the base structure 210 on the ground,

- positioning the lower mast section 240 so that the foot end of the lower mast section is brought adjacent the base structure;

connecting the foot end of the lower mast section to the base structure;

supplying the drilling drawworks 242;

positioning and mounting the drilling drawworks onto the lower section of the drilling mast; - moving the drilling rig mast with the drilling drawworks towards its vertical operational position. Advantageoulsy, the method includes the use of the drilling drawworks ramp 200, and the method includes the steps of:

positioning the base structure on the ground,

positioning the lower mast section so that the foot end of the lower mast section is brought adjacent the base structure;

connecting the foot end of the lower mast section to the base structure;

supplying the drilling drawworks ramp 200, preferably by a vehicle, and positioning the drilling drawworks ramp adjacent the lower section,

supplying, preferably by means of a vehicle, the drilling drawworks 242 to the drilling drawworks ramp;

sliding the drilling drawworks over the sliding surface to the lower section of the drilling mast; mounting the drilling drawworks to the lower section;

removing the drilling drawworks ramp. Possibly the method further comprises the step of installing a drawworks subframe 245 onto the substantially horizontal lower mast section, as has already been installed in fig. 6a.

So, it is illustrated here that the drilling drawworks is mounted to the lower mast section, possibly via a drawworks subframe, prior to the erection of the transfigurable drilling rig system.

It is illustrated that advantageously a drilling drawworks ramp 200 is used, which is positioned, here by a vehicle 230, in line with and connected to the lower mast section 240 (fig. 6A), via connection means 208, 209 (fig. 6B). Drilling drawworks are provided to the ramp 200, here by a vehicle 233 (Fig. 7A), possibly the same vehicle as provided the drilling drawworks ramp 200. The drilling drawworks are allowed to slide over the sliding surface 201 of the drilling drawworks ramp 200 onto the lower mast section 240, in particular onto the drawworks subframe 245 mounted onto the lower mast section 240 (Fig. 7B). Here, sliding occurs by operating the winch 205 actuating the winch driven cable 202. Then the drilling drawworks ramp is removed, as illustrated in fig. 7C. Subsequently the other mast sections may be connected to the lower mast section, similar to what is shown in figs. 3A-3C or 5a, 5b.