The present invention relates to a drilling rig and a method for use thereof.

A drilling rig is a machine that creates holes in the earth sub-surface. Drilling rigs are normally very massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells. The term "rig" generally refers to the complex of equipment that is used to penetrate the surface of the Earth's crust and is used also in this context for the present invention.

Larger rigs are capable of drilling through thousands of meters of the Earth's crust, using large mud pumps to circulate drilling mud (slurry) through the drill bit and the mud travels back up to the surface around the outside of the drill pipe, called the annulus. The drilling mud is used for cooling and removing cuttings while a well is drilled. Hoists in the rig may have to lift hundreds of tons of pipe, and is therefore very heavy equipment.

Such large drilling rigs are complex and require a lot of maintenance.

Consequently, these conventional drilling rigs are also labor intensive. They also comprise many parts and subsystems which require technical or legal certification.

US-A-4,645,084 discloses a self contained, portable, relatively light weight robot arm or boom assembly adapted to be mounted on a conventional truck body or on the ground at the work site to accurately and fixedly suspend a power tool, such as a drill or jack hammer. A drill as disclosed is capable of drilling shallow holes up to a few meters of depth.

An object of the present invention is to provide a drilling rig and method for use thereof, that is improved relative to the prior art and wherein at least one of the above stated problems is in whole or partly obviated.

Such objectives as indicated above, and/or other benefits or inventive effects, are attained according to the present disclosure by the assembly of features in the appended independent device claim and in the appended independent method claim.

The invention is directed to a drilling rig configured to drill deep wells, comprising an articulated arm with at least two arm sections, and wherein a drilling motor assembly is pivotally arranged on one of the arm sections. A drilling motor assembly according to the invention comprises a drilling motor and associated elements such as a pipe handler. Such a drilling motor assembly is also known as a top drive. The-drilling motor assembly is configured for connecting and handling of a pipe segment and holding this pipe segment when the drilling motor engages said pipe segment in a screwing manner. The drilling motor is configured for drillable driving the pipe segment. The drilling motor assembly is preferably pivotably arranged at or near an end of an arm section. The pivotable arrangement allows the drilling motor assembly to connect and handle a pipe segment under various angles. Compared to a conventional drilling rig, a drilling rig with an articulated arm is more compact and comprises considerably less parts. Besides increasing the reliability, a lower number of parts is also advantageous from a certification and legislation aspect. A drilling rig comprising an articulated arm may be constructed lighter, which provides possibilities to transport the rig (in pieces) to a new drilling location.

According to a further preferred embodiment, the articulated arm is supported by an arm support that is rotatably arranged on a sub structure, and wherein the arm support is rotatable with respect to an arm support rotation axis. By rotating the arm support with respect to the arm support axis, the arm may be placed in different positions, allowing rotational positioning of a string of (drill)pipes e.g.in preparation for deviated drilling . By changing the position of the articulated arm, the direction wherein a drill bit is positioned may be adapted. The rotatable arm support makes it possible to accurately adjust the orientation of the drill bit, even when the (drill)pipe is connected to an idle drilling motor. Also, a rotatable arm support allows the articulated arm to pick up and put back tools and pipe segments arranged around the arm support. Such tools may be a riser running tool and/or a casing running tool, but are not limited thereto.

According to an even further preferred embodiment, the sub structure further comprises a rotary support table comprising a rotary support table through hole and a pipe clamping device, wherein the rotary support table is rotatable with respect to a rotary support table rotation axis. The pipe clamping device may comprise slips. The rotary support table is provided for holding a string of connected pipe segments while a new pipe segment is pickup up by the articulated arm. By connecting successive pipe segments a string may be formed in order to drill deep wells through, if desired, thousands of meters of the Earth's crust.

According to an even further preferred embodiment, the arm support is rotatably drivable by an arm support drive.

According to an even further preferred embodiment, the sub structure comprises a through hole that at least coincides with the arm support rotation axis. In this way, the drill bit and pipe segments may be lowered substantially at or near the arm rotation axis. This configuration furthermore allows for a relatively compact drilling rig. Furthermore, the force moment arm of the articulated arm is limited with respect to an articulated arm that would drill off-center from its own rotation axis. Therefore, the drilling rig may be constructed lighter, which provides the possibility to transport the rig (in pieces) to a new drilling location.

According to an even further preferred embodiment, the through hole in the sub structure is coaxially arranged with respect to the arm support rotation axis.

Although the articulated arm may be operated by a human operator, the articulated arm is according to a preferred embodiment an at least partially automated robot arm. According to an even further preferred embodiment, the rotary support table is rotatably drivable with a rotary support table drive. By rotating the pipe segments that are held by the rotary support table, it is prevented that these pipe segments get stuck to the bore well.

According to an even further preferred embodiment, the arm support and the rotary support table are coaxially arranged with respect to each other, thereby allowing the articulated arm to lower a pipe segment through both the arm support and the rotary support table.

According to an even further preferred embodiment, the arm support and the rotary support table are independently from each other rotatable. This provides great advantages, as the arm support may be rotated while drilling. As soon as the drilling operation stops, the arm support is already brought in the desired orientation for the next operation in the drilling process. For example, it may be positioned for picking up a new pipe segment or a tool. This will increase the speed of the process.

According to an even further preferred embodiment, at least one of the arm sections comprises a linkage system with two arm sub sections extending in longitudinal direction of said arm section.

According to an even further preferred embodiment, two arm sections comprise a linkage system with two arm sub sections extending in longitudinal direction of said arm section. If both arm sections are provided with a linkage system in the form of a parallelogram construction, the drilling motor assembly may be reliably lowered perpendicular to the sub structure on which the arm support is arranged. This is advantageous during drilling and the perpendicular lowering will not be influenced even when a drilling vessel would pitch due to the movement of the sea and consequently the drilling rig assembly. Also, due to the nature of the assembly, the center of gravity may be adapted, i.e. in rough seas one could decide not to work with stands made out of two or three pipe segments as usual, but limit oneselves to running one segment at the time. This keeps the articulated arm and drilling motor assembly at a lower level, and hence the center of gravity will be lower.

According to an even further preferred embodiment, the arm section that comprises the linkage system is pivotably arranged on the arm support.

According to an even further preferred embodiment, at least one of the arm sub sections comprises a length adjuster. Use of a length adjuster has several advantages. Even if only one of the arm sections comprises a linkage system with two arm sub sections extending in longitudinal direction of said arm section as described above, the use of a length adjuster would allow the drilling motor assembly to be reliably lowered perpendicular to the sub structure on which the arm support is arranged. If a single linkage system would function as a parallelogram construction, this would result in a transverse displacement of the drilling motor assembly with respect to the through hole in the sub structure. The length adjuster on the one hand allows for a compensation of such a transverse displacement, therefore being able to maintain the drilling motor assembly as the desired position.

On the other hand, by adjusting the length of one arm sub section, the linkage system allows the arm sections of the articulated arm to function as a crane. The drilling motor assembly may be pivoted with respect to the arm support, wherein this assembly is pivoted away from the arm support rotation axis.

According to an even further preferred embodiment, the length adjuster of the arm sub section comprises a hydraulic cylinder.

According to an even further preferred embodiment, at least one of the at least two arm sections of the articulated arm comprises a hydraulic actuator configured for lifting and lowering said arm section, wherein said hydraulic actuator is connected to an accumulator configured for storing energy when said arm section is lowered and configured for re -using said stored energy when said arm section is moved upwards again.

The invention is further directed to a method of using a drilling rig according to the invention, comprising the step of pivoting the drilling motor assembly with respect to the arm section of the articulated arm and connecting a pipe segment with said drilling motor assembly. This has the advantage that no other pipe grabbing equipment like prior art elevators are needed, in both tripping out and tripping in direction.

According to a preferred embodiment said method further comprises the step of connecting successive pipe segments to form a string of pipe segments. Using a string of pipe segments, it is possible to drill deep wells through, if desired, thousands of meters of the Earth's crust.

According to a preferred embodiment said method further comprises the steps of pivoting the drilling motor assembly in a first pivot direction with respect to the arm section of the articulated arm and connecting a pipe segment with said drilling motor assembly, pivoting the drilling motor assembly in a second pivot direction that is opposite the first pivot direction, and drillable driving said pipe segment with said drilling motor assembly in downward direction.

According to a further preferred embodiment, said method comprises the step of rotating the arm support independently from the rotary support table. This allows the articulated arm to be positioned for a next operation in the drilling process.

According to an even further preferred embodiment, said method comprises the step of the length adjuster adjusting the length of the arm sub section.

In the following description preferred embodiments of the present invention are further elucidated with reference to the drawing, in which shows:

Figure 1 : a schematic presentation of a prior art drilling rig; Figures 2-4: schematic presentation of a drilling rig according to a first embodiment of the invention in three successive states;

Figure 5: a schematic top view of the drilling rig of figures 2-4;

Figures 6 and 7: a schematic presentation of a drilling rig according to a second embodiment of the invention in two successive states;

Figure 8: a detailed view of an arm support and rotary support table according to the embodiment of figures 6 and 7; and

Figure 9: : a schematic presentation of a drilling rig according to a third embodiment of the invention.

The prior art drilling rig 1 shown in figure 1 comprises a sub structure 2 with a derrick 3. Drill line 4 is arranged on the derrick 3 and is connected to a travelling block 5 which in turn is connected to a drilling motor assembly comprising a drilling motor 6 and a pipe handler 7. Pipe segment 11 is picked up/lowered down from and onto the catwalk 104 by use of an elevator 112 and links 114. The drilling motor assembly comprises a drilling motor 6 and a pipe handler 7, wherein the pipe handler 7 is configured to hold a pipe segment 11 when a main shaft of the drilling motor 6 connects with the pipe segment 11 in a screwing manner. The drilling motor assembly is provided with power via a power supply 8. The sub structure 2 comprises a rotary table 9 and a roughneck 10 (or any other equipment like tongs) for connecting/disconnecting pipe segments 11. The top of the well 116 is provided with a blow out preventer 12.

In contrast to the complex prior art drilling rig 1 of figure 1 , the drilling rig 20 according to the invention shown in figure 2 comprises an articulated (robot) arm 22 with two arm sections: first arm section 24 and second arm section 42. A drilling motor assembly 86 comprising a drilling motor 90 and a pipe handler 88 is pivotally arranged on the outer end of the second arm section 42 at a second pivot 46 thereof. The articulated arm 22 is supported by an arm support 60 that is rotatable arranged on the sub structure 68. The arm support 60 is rotatable with respect to an arm support rotation axis 62 and is rotatable drivable by an arm support drive 64.

The first arm section 24 of the articulated (robot) arm 22 is pivotally connected with the arm supper 60 at a first pivot 30. The first arm section 24 on the other end thereof comprises a second pivot 32. This second pivot 32 of the first arm 24 pivotally connects with the first pivot point 45 of the second arm section 42. The second arm section 42 on the other end thereof comprises a second pivot 46. The drilling motor assembly 86 is pivotably with respect to the second pivot 46 and is therefore capable of grabbing and connecting to pipe segments 92 and tools 94 in different orientations.

Figure 2 further shows a pipe make up/break out station 100 and pipe or tool offering station 102, as well as a catwalk 104 which offers a pipe segment 92 to the drilling motor assembly 86. A roughneck 106 (or any other suitable tools like tongs) is provided for connecting/disconnecting pipe segments 92 and a blow out preventer 108 is arranged on top of the well 116 in the ground 110.

The articulated (robot) arm 22 may be pivoted around the pivot points 30, 32, 45 and 46 using first hydraulic actuator 52 and second hydraulic actuator 54 and third hydraulic actuator 56 respectively.

In figure 2 a pipe segment 92 is picked up from the catwalk 104. This is after the drilling motor 90 has connected to and picked up the segment at the tool- or pipe offering station 102. In figure 3 the articulated (robot) arm 22 has moved and the drilling motor assembly 86 has pivoted around the second pivot point 46 of the second arm section 42 so that the pipe segment 92 is substantially vertically oriented. In the state shown in figure 2, the pipe segment 92 is already connected to a previous pipe segment 92 using the roughneck 106. Figure 4 shows the situation wherein the drilling motor assembly 86 has lowered the pipe segment 92 into the ground 110.

A second and even more preferred embodiment of a drilling rig 20 according to the present invention is shown in figures 6 and 7. For parts that are also subject of the previous embodiment, same reference numbers have been applied and a repetition of a detailed description is omitted. The second embodiment shown in figures 6 and 7 however differs from the first embodiment of the previous figures in that the articulated (robot) arm 22 now comprises a first arm section 24 with a linkage system 26. This linkage system 26 comprises a first longitudinal arm sub section 28 with a first pivot point 30 and a second pivot point 32. The linkage system 26 furthermore comprises a second longitudinal arm sub section 34 that comprises a first pivot 36 and a second pivot 38. When the first longitudinal arm sub section 28 and second longitudinal arm sub section 34 have the same length, the linkage system 26 will function as a parallelogram construction. However, the linkage system 26 of the first arm section 24 is provided with a length adjuster 40 in the second longitudinal arm section 34, allowing for a pure vertical displacement of the drilling motor assembly 86. Furthermore, the length adjuster 40 may pivot the second arm section 42 around second pivot 32 of the first longitudinal arm sub section 28, resulting in a cranelike movement of the articulated (robot) arm 22 as shown in figure 6.

In the shown embodiment the articulated (robot) arm 22 again comprises a first hydraulic actuator 52, a second hydraulic actuator 54 and a third hydraulic actuator 56. The second hydraulic actuator 54 is arranged between the arm support 60 and the second longitudinal arm sub section 34, but may also be arranged between the second pivot point 38 and the second longitudinal arm sub section 34. The second hydraulic actuator 54 functions as the length adjuster 40 and may also pivot the first arm section 24 and the second arm section 42 relative to each other.

In the shown embodiment, hydraulic actuator 52 is connected with an accumulator 58 that is configured for storing energy. When the first arm section 24 is lowered, hydraulic fluid leaving the hydraulic actuator 52 is stored in the accumulator 58, and re -used when the hydraulic actuator 52 has to lift the first arm section 24 again.

Figure 8 shows a detailed overview of the arm support 16 that comprises a through hole 70 and an arm support rotation axis 62. The arm support 60 is drivable with respect to the (not shown) sub structure 68 by the arm support drive 64. The arm support 60 is supported by arm support bearings 66 arranged in the (not shown) sub structure 68.

Furthermore, a rotary support table 74 is provided that comprises a rotary support table through hole 76 wherein slips 78 may be arranged for holding a pipe segment 92.

The rotary support table 74 is supported by rotary support table bearing 84 and is drivable by a rotary support table drive 82 around a rotary support table rotation axis 80.

The rotary support table through hole 76 and the through hole 70 of the arm support 60 are coaxially arranged, and therefore the arm support rotation axis 62 and the rotary support table rotation axis 80 going inside.

This specific configuration shown in figure 8 is advantageous, because it allows a pipe segment to be lowered along the rotation axes 62, 80 through the through holes 76, 70. Even while drilling or otherwise rotation of the pipe segments the arm support 60 may be rotated with respect to the (not shown) sub structure 68, thereby allowing the articulated arm 22 to be already positioned/oriented for a next processing step in the drilling process. This may the picking up of a tool as shown in figure 5 for the first embodiment.

Furthermore, via rotating the arm support 60 a very accurate rotational positioning

(drill)pipe in the well is possible, allowing for e.g. accurate deviated drilling or otherwise required rotational positioning of the pipe.

Figure 9 shows a third embodiment of a drilling rig 1 according to the invention, wherein the first arm section 24 and the second arm section 42 both comprise a linkage system 26, 43. The linkage system 26 of the first arm section 24 is identical to the linkage system 26 of the second embodiment, as shown in figures 6 and 7. In this third embodiment, the second arm section 42 comprises a similar linkage system 43 as the linkage system 26 of the first arm section 24. The linkage system 43 of the second arm section 42 also comprises two arm sub sections 44, 47 extending in longitudinal direction of said second arm section 42. The first arm sub section 44 extends between a first pivot 45 and a second pivot 46 thereof. The second arm sub section 47 extends between a first pivot 48 and a second pivot 49 thereof. The second arm sub section 47 further comprises a length adjuster 50, which according to this third embodiment is formed by the third hydraulic actuator 56. If the length adjuster 40 maintains the length of the second longitudinal arm sub section 34 of the first arm section 24 at the same length as the first longitudinal arm sub section 28 of the first arm section 24, the linkage system 26 of the first arm section 24 functions as a parallelogram construction. Likewise, if the length adjuster 50 maintains the length of the second longitudinal arm sub section 47 of the second arm section 42 at the same length as the first longitudinal arm sub section 44 of the second arm section 42, the linkage system 43 of the second arm section 42 also functions as a parallelogram construction. If both the linkage system 26 of the first arm section 24 and the linkage system 43 of the second arm section 42 function as a parallelogram construction, the drilling motor assembly 86 may be reliably lowered perpendicular to the sub structure 68 on which the arm support 60 is arranged.

Although they show preferred embodiments of the invention, the above described embodiments are intended only to illustrate the invention and not to limit in any way the scope of the invention. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims. Furthermore, it is particularly noted that a skilled person can combine technical measures of the different embodiments. The scope of the invention is therefore defined solely by the following claims.