Drilling support device, drilling system and method for operating a drilling system

Abstract

The invention relates to a drilling support device (10) for connection to a bottom hole assembly (12) to be used in a wellbore (14), comprising a support unit (16) including at least one gripping unit (18) configured to anchor the bottom hole assembly (12) in the wellbore (14) and at least one force providing unit (20) configured to supply weight on a drill bit (22) of the bottom hole assembly (12).

Description

[0001] Drilling support device, drilling system and method for operating a drilling system

[0002] State of the art

[0003] The invention relates to a drilling support device according to claim 1 , a drilling system according to claim 14 and a method for operating a drilling system according to claim 15.

[0004] Conventional drilling methods are well known and are used, for example, in oil, gas, water and geothermal drilling. In conventional drilling, a drill string consisting of a drill bit, drill pipe and other elements is driven above ground, e.g. by means of a rotary table or a top drive connected to the drill string and supplying the torque. Weight on bit, i.e. the downward force exerted on the drill bit, conventionally is provided by thick-walled and heavy drill collars, which are arranged directly above the drill bit in conventional bottom hole assemblies. Weight on bit is an essential parameter in the drilling process, as it determines the rock-breaking performance, drill bit wear and the overall wellbore quality. Conventionally weight on bit is controlled by lifting and lowering the drill string using the drawworks of the drilling rig. However, conventional drilling rigs have a very large footprint and are therefore unsuitable for use in areas with limited space, e.g. in urban areas. In the context of the energy transition, however, it is becoming increasingly important to enable deep geothermal drilling in such areas as well. Unconventional and space saving drilling methods must be used here, which, for example, do not use a drill string to transmit the torque from above ground, but a downhole-drive that is part of the bottom hole assembly, which is lowered into the wellbore on a wire rope, for example. However, such unconventional drilling methods are associated with a number of technical challenges that have not yet been successfully solved in the state of the art. One challenge is to put enough weight on the bit without using a drill string comprising drill collars. Another challenge is to anchor the bottom hole assembly in the wellbore if it is not connected to a drive on the surface via a drill string. It is necessary to anchor the bottom hole assembly in the wellbore in a torsion-proof manner in order to be able to transfer enough torque to the drill bit to crush the formation and enable precise drilling. An object of the invention is, in particular, to provide a drilling support device which solves the above-mentioned technical problems and facilitates to improve drilling efficiency, especially when using unconventional drilling methods in areas with limited space.

[0005] According to the invention, the problem is solved by the features of claims 1 and 15, whereby advantageous embodiments of the invention can be derived from the dependent claims.

[0006] Advantages of the invention

[0007] A drilling support device for connection to a bottom hole assembly to be used in a wellbore is proposed, comprising a support unit including at least one gripping unit configured to anchor the bottom hole assembly in the wellbore and at least one force providing unit configured to supply weight on a drill bit of the bottom hole assembly.

[0008] By means of the invention advantageously a drilling efficiency can be improved, in particular when using unconventional drilling methods in areas with limited space, such as in urban areas. By means of the gripping unit advantageously the bottom hole assembly can be anchored in the wellbore in a torsion-proof manner, allowing to transfer torque from a downhole-drive to the drill bit and thus enabling precise drilling and increasing drilling efficiency. In addition, the force providing unit advantageously can be used to apply weight on the drill bit and increase rock breaking performance and thus drilling efficiency. Advantageously, the force providing unit also enables precise control of the weight on the drill bit, which can thus be adapted to the respective conditions of the formation to be drilled. This can also advantageously prevent excessive wear of the drill bit and improve drilling efficiency in this respect, too. Since the gripping unit and the force providing unit are both parts of the support unit and are advantageously combined in one assembly, a particularly compact design can also be achieved, thus providing a spacesaving drilling support device that is particularly suitable for use in areas with limited space.

[0009] In this document a “drilling support device” is to be understood as a device, which is configured for connection to a bottom hole assembly in order to support a drilling process. Drilling processes that can be carried out with the aid of the drilling support device preferably concern the construction of deep wellbores of at least 400 m depth, which are particularly intended for deep geothermal energy applications. However, the drilling support device is not limited to use for the construction of deep wells, but can also be used for the construction of less deep wells, e.g. for near-surface geothermal energy applications. The drilling support device is also not limited to use in geothermal applications, but can also be used in other drilling tasks, e.g. in the construction of oil, gas or water wells or in the construction of underground storage facilities, e.g. for the storage of gas or hydrogen or carbon dioxide capture and storage (CCS).

[0010] The drilling support device is configured for connection to a bottom hole assembly, whereby it is not limited to a specific configuration of the bottom hole assembly. Bottom hole assemblies suitable for use in combination with the drilling support device according to the present invention, comprise at least one drill bit and can also additionally comprise other components. It is conceivable that the drilling support device is used as a part of a drill string in connection with a surface drive and a conventional bottom hole assembly comprising a drill bit, drill collars, heavy-weight drill pipes and other components where applicable, such as stabilizers, jars, crossovers, measurement-while-drilling tools, loggingwhile-drilling tools and the like. Preferably, however, the drilling support device is configured for use in connection with unconventional bottom hole assemblies, which comprise at least one drill bit and a drive unit, which is located downhole, wherein the bottom hole assembly is not intended to be connected to a surface drive via a drill string, but instead can be lowered into a wellbore by means of a wire rope, for example. The drilling support device is preferably configured to be used in combination with drilling fluids present in the wellbore, wherein the drilling fluid, depending on the type of bottom hole assembly and drilling process selected, can either remain static or circulate in the wellbore without affecting the functionality of the drilling support device. Preferably the drilling support device is not limited to applications with a certain type of drilling fluid, but, depending on the drilling conditions and the requirements of the formation to be drilled, is suitable for use with both water-based and oil-based drilling fluids, which may contain a variety of additives such as bentonite, barite and the like. Unconventional and conventional bottom hole assemblies suitable for use in combination with the drilling support device according to the present invention are not limited to a particular type or diameter of the drill bit and may comprise exactly one drill bit or more than one drill bit. For example, a suitable bottom hole assembly may comprise exactly one drill bit, which could be embodied as roller-cone bit or a polycrystalline diamond compact (PDC) bit or any other type of drill bit that appears to be useful to the person skilled in the art for a certain drilling application. A suitable bottom hole assembly may comprise a plurality of two or more drill bits in combination, for example a core bit and an underreamer. It is for example also conceivable that the bottom hole assembly comprises a bicenter bit, i.e. an integral bit and eccentric reamer used to simultaneously drill and underream the wellbore.

[0011] The support unit comprises at least the gripping unit and the force providing unit and may additionally comprises other components of the drilling support device. The gripping unit is configured to anchor the bottomhole assembly in the wellbore and has suitable means for this purpose. Preferably the gripping unit is configured to anchor the bottom hole assembly in the wellbore in a torsion-proof manner and in such a way that torque from a downhole-drive of the bottom hole assembly can efficiently be transferred to the drill bit. Preferably, the gripping unit is configured to detachably anchor the bottom hole assembly in the wellbore. The gripping unit is not limited to a specific type of anchoring. Depending on the configuration, the gripping unit may be configured to anchor the bottomhole assembly in open-hole wellbores, i.e. wellbores that are not yet provided with a casing, or cased-hole wellbores, i.e. wellbores that are provided with casing at least section-wise and are to be drilled further from a cased section. The gripping unit may be configured to anchor the bottom hole assembly in a force-fit and / or form-fit manner. For example, the gripping unit may comprise at least one means, which is configured to generate a contact pressure against an inner wall of the wellbore in order to anchor the bottom hole assembly in the wellbore. Alternatively, or in addition, it would also be conceivable that the gripping unit comprises at least one means, e.g., a metal plate or hook or a blade or the like, which is configured to at least partly penetrate an inner wall of the wellbore in order to anchor the bottom hole assembly in the wellbore. For cased-hole wellbores it is also conceivable that the gripping unit may comprise at least one means, which is configured to interact with a counterpart of the casing in order to anchor the bottom hole assembly in the wellbore. For example, the gripping unit may comprise at least one means, which is configured to be connected to a counterpart of the casing in a form-fit and / or force-fit manner, e.g. screwed or clamped or the like, and / or which is configured to be magnetically connected to the counterpart of the casing.

[0012] The force providing unit is configured to supply weight on the drill bit of the bottom hole assembly and has suitable means for this purpose. Preferably the force providing unit is configured to supply weight on the drill bit with a variable amount, which is adjustable depending on the drilling conditions. More preferably the force providing unit is configured to supply weight on the drill bit with a variable amount, which is automatically adjustable depending on the drilling conditions. The force providing unit comprises at least one means for the supply of weight on the drill bit, which can be connected to the drill bit either directly or indirectly. The force providing unit is not limited to a specific type of means for the supply of weight on the drill bit. Means of the force providing unit for the supply of weight on the drill bit, for example and without being limited thereto, may be embodied as hydraulic or pneumatic piston or an electromechanical actuator or a spring element or the like.

[0013] In the present document, numerical words such as "first" and "second", which precede certain terms, merely serve to differentiate objects and / or to assign objects to one another and do not imply an existing total number and / or ranking of objects. In particular, a "second object" does not necessarily imply the existence of a "first object".

[0014] The term "configured" is to be understood to mean specially designed and / or equipped. By the fact that an object is configured to perform a specific function, it should be understood that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0015] It would be conceivable that the gripping unit and the force providing unit are configured to be operated by different working mediums. For example, the gripping unit might be configured to be pneumatically operated and the force providing unit might be configured to be electrically or hydraulically operated or vice versa. In an advantageous implementation of the invention, however, it is proposed that the gripping unit and the force providing unit are configured to be operated by the same working medium. Thereby advantageously an efficiency can be further improved. In particular a material-efficient and space saving design of the drilling support device can be achieved. Without being limited thereto, suitable working mediums to operate the gripping unit and the force providing could be hydraulic working mediums, such as hydraulic oil or water or the like, and / or pneumatic working mediums, such as compressed air or other compressed gases, e.g. nitrogen.

[0016] It is conceivable that the gripping unit and the force providing unit are each configured to be pneumatically or electrically operated, for example. In a particularly advantageous embodiment of the invention, however, it is proposed that the gripping unit and the force providing unit are configured to be hydraulically operated. This has the advantage of ensuring a particularly reliable and less error-prone operation of the support unit.

[0017] Further, it is proposed that the drilling support device comprises a storage unit for storing a source of energy for the operation of the support unit. Thereby advantageously an operational efficiency can be increased. A “source of energy” in this context means a source that is suitable for supplying energy for and / or transmitting energy to the support unit. The storage unit may comprise at least one means for storing electrical energy, for example a rechargeable battery and / or a fuel cell and / or the like. The storage unit may comprise at least one means for storing chemical energy, for example fuel or natural gas or hydrogen or the like. Preferably the storage unit comprises at least one means for storing physical energy, advantageously in the form of a working medium to operate the gripping unit and the force providing, for example a tank for storing hydraulic working medium and / or or a pressure vessel for storing compressed pneumatic working medium and / or the like.

[0018] Moreover, it is proposed that the drilling support device comprises a pump to operate the gripping unit and the force providing unit. This advantageously enables reliable operation and precise control of the gripping unit and the force providing unit. The pump could, for example, be embodied as a centrifugal pump or as a piston pump or as any other pump that appears to be suitable to the person skilled in the art. In this embodiment the gripping unit and the force providing unit are preferably configured to be hydraulically or pneumatically operated. The drilling support device could comprise a separate drive, e.g. an electric drive, for operating the pump. In an advantageous embodiment of the present invention, however, it is proposed that the pump is configured in such a way that it can be driven by a drive unit of the bottom hole assembly which is also intended to drive the drill bit. This allows for a further increase in efficiency and a space saving design. The bottom hole assembly may comprise a drive shaft, which is connected to the drive unit, which is extending through the components of the drilling support device and which is configured for transmitting torque from the drive unit to the at least one drill bit of the bottom hole assembly, wherein the drive shaft has at least one connection element for connection to the pump so that part of the torque provided by the drive unit can be utilized to operate the pump. In Addition, it is proposed that the storage unit comprises at least one hydraulic tank for storing a hydraulic working medium for the operation of the support unit. Thereby advantageously an efficient operation of the support unit can be achieved. Preferably the storage unit comprises at least one piston cylinder which is arranged in the hydraulic tank. Advantageously the piston cylinder is guided by at least one cylinder shaft arranged in the hydraulic tank.

[0019] In an advantageous embodiment of the present invention, it is further proposed that the hydraulic tank comprises at least one opening for pressure compensation, which is configured to allow drilling fluid to flow from the wellbore into the hydraulic tank and drilling fluid to flow out of the hydraulic tank into the wellbore. Preferably the hydraulic tank is not limited to an application with a certain type of drilling fluid, but, depending on the drilling conditions and the requirements of the formation to be drilled, is suitable for use with both water-based and oil-based drilling fluids, which may contain a variety of additives such as bentonite, barite and the like. It is also conceivable to make the tank from a particularly chemically resistant material, e.g. titanium, if required, for example if drilling fluids that contain acids are used. Preferably in an operational position of the drilling support device, the at least one opening of the hydraulic tank is located at its upper end. However, other locations for the at least one opening are also conceivable as an alternative. Preferably, the hydraulic tank is configured such that the hydraulic working medium is located above the piston cylinder in an initial state, wherein the piston cylinder is configured such that it moves upwards in order to push the hydraulic working medium out of the hydraulic tank, wherein drilling fluid can flow through the opening into a space which becomes free below the piston cylinder. Thereby advantageously only the bottom of the piston cylinder is exposed to the drilling fluid, which prevents debris, such as particles of the drilling mud, from being deposited on the piston cylinder and hindering its movement and / or wearing it down. For this purpose, the hydraulic tank may comprise at least one drilling fluid tube, which is in fluid connection with the at least one opening. The at least one drilling fluid tube can be arranged inside the hydraulic tank and extend through the piston cylinder, such that the piston cylinder is movably supported surrounding the at least one drilling fluid tube. For example, in the initial state hydraulic working medium can be stored inside the hydraulic tank above the piston cylinder and the at least one drilling fluid tube, which is in fluid connection with the at least one opening, allows drilling fluid to flow to a space that becomes free below the piston cylinder, when it moves up, while hydraulic working medium and drilling fluid are fluidically separated from each other by the piston cylinder. The hydraulic tank may further comprise at least one hydraulic working medium tube, which is fluidically connected a space above the piston cylinder, where the hydraulic working medium is stored, allowing the hydraulic working medium to flow out of the hydraulic tank and back in respectively. The at least one hydraulic working medium tube can also be arranged inside the hydraulic tank and extend through the piston cylinder, such that the piston cylinder is movably supported surrounding the at least one hydraulic working medium tube. In such a configuration the hydraulic working medium advantageously must cover a greater distance when flowing back into the hydraulic tank through the at least one hydraulic working medium tube, which enables it to cool down more efficiently. However, in the alternative, it is also conceivable that the hydraulic tank is is configured such that the hydraulic working medium is located below the piston cylinder in the initial state, wherein the piston cylinder is configured such that it moves downwards in order to push the hydraulic working medium out of the hydraulic tank, wherein drilling fluid can flow through the opening into a space which becomes free above the piston cylinder.

[0020] Moreover, it is proposed that the drilling support device comprises a filtering unit arranged at the at least one opening and configured to prevent at least larger particles, e.g. drill cuttings generated by the drilling process, from entering the hydraulic tank. This has the advantage of reducing wear of the hydraulic tank and the components located therein. Moreover, advantageously the pump and other components of the drilling support device, such as valves and the like, can be protected, if the drilling support device comprises a filtering unit arranged at the at least one opening. Thereby further advantageously a correct functioning of the drilling support device can be ensured and high efficiency can be maintained. The filter unit comprises at least one filter element, which, without being limited thereto, can be embodied, for example, as a mesh or the like. The at least one filter element of the filter unit has a passage diameter that defines the average size of the particles that can pass through the filter element, whereby larger particles are retained. The at least one filter element has a passage diameter, which is in particular less than or equal to 1.000 mm, advantageously less than or equal to 0.500 mm, particularly advantageously less than or equal to 0.250, preferably less than or equal to 0.150 mm and particularly preferably less than or equal to 0.105 mm and most preferably less than the average particle size of bentonite, in particular less than 36.000 pm. The filter unit may comprise a plurality of filter elements. Preferably the filter unit comprises at least one filter element for each opening of the hydraulic tank. It is also conceivable that the filter unit comprises more than one filter element for each opening of the thank, whereby the filter elements can be arranged one behind the other and can have a decreasing passage diameter towards the inside of the tank.

[0021] Further, it is proposed that the drilling support device comprises a control unit configured to control the gripping unit and the force providing unit independently of one another. This advantageously allows for ease of operation. In particular during the drilling process the weight on the drill bit supplied by the force providing unit advantageously can be controlled without influencing the anchoring of the bottom hole assembly by means of the gripping unit. Preferably, the control unit comprises a hydraulic valve assembly with a plurality of hydraulic valves which can be controlled electronically and independently of one another. Without being limited thereto, the hydraulic valves can be embodied as solenoid valves, for example, or as any other type of valves that appear to be suitable for the person skilled in the art.

[0022] In an advantageous embodiment of the invention, it is further proposed that the gripping unit comprises at least one extendable member which is configured to anchor the bottom hole assembly in the wellbore. Thereby advantageously ease of operation of the gripping unit can be achieved. The extendable member is configured to be movable between an extended position and a retracted position. In the extended position an outside diameter of the support unit is determined by the extendable member and corresponds at least to a diameter of the wellbore. The extendable member advantageously is configured to generate a contact pressure against an inner wall of the wellbore in the extended position in order to anchor the bottom hole assembly in the wellbore. It is also conceivable that the outside diameter of the support unit in the extended position of the extendable member exceeds the diameter of the wellbore. This is for example the case when the extendable member is configured to at least partly penetrate an inner wall of the wellbore in order to anchor the bottom hole assembly in the wellbore. The extendable member could be configured to be mechanically actuated, for example by means of at least one spring or other elastic element, which pushes the extendable member outwards in the extended state. The extendable member could be configured to be electromechanically actuated, for example by means of an actuator which pushes the extendable member outwards in the extended state. Preferably the extendable member is configured to be pneumatically or hydraulically actuated. For example, the extendable member may be configured to be actuated by a pneumatic or hydraulic piston, which pushes the extendable member outwards in the extended state. Without being limited thereto, the extendable member could be embodied as a plate, in particular a metal plate, or as hook or a blade or any other type of element suitable to at least partly penetrate an inner wall of the wellbore in order to anchor the bottom hole assembly in the wellbore. The extendable member could also, for example, be embodied as force looking and or frictional connection element, e.g. a clamping element or as an elastic rubber element, which can be expanded by pressurization, or the like. In a particular advantageous embodiment of the invention, however, it is proposed that extendable member is embodied as an inflatable element. Thereby advantageously a particularly compact and space-saving design of the gripping unit can be achieved. Moreover, a less error-prone and reliable operation can be achieved, as the number of mechanical parts can be minimized, when the extendable member is embodied as an inflatable element. Preferably the inflatable element has at least one cavity, in particular a membrane, which is configured to be filled with an inflation medium to bring the inflatable element into the extended state and which can be sealed pressure-tight. Advantageously the inflatable element is configured to be used with pneumatic and / or hydraulic working medium as an inflatable medium. Without being limited thereto, the inflatable element can, for example, be made from rubber or fabric and can be in particular reinforced, e.g. wire reinforced. It is also conceivable that the inflatable element is made from a thin metal sheath.

[0023] Further, it is proposed that the force providing means comprises at least one double acting piston. Such an embodiment advantageously enables precise control of the weight to be applied to the drill bit. Thus, the drilling efficiency can be further increased. Preferably, the double acting piston is configured to transfer forces to and receive forces from the bottom hole assembly. Preferably, the force providing unit comprises at least one hydraulic chamber, in which the piston is arranged and is preferably supported by at least one cylinder shaft. Preferably, the double acting piston is connected to at least one force transmission element, e.g. a cylinder rod, which is configured to transmit force from the double acting piston to the drill bit and vice versa. Preferably, the force providing unit is configured to be operated in at least two different operating modes, in particular by means of the control unit. For a normal operating mode of the force providing unit, the double acting piston is configured to be pressed in a direction towards the drill bit of the bottom hole assembly, in particular downwards, by means of hydraulic fluid which is pumped into the hydraulic chamber from a first side, whereby weight on the drill bit is applied. For a reverse operating mode of the force providing unit, the double-acting piston is configured to be pressed in a direction away from the drill bit of the bottom hole assembly, in particular upwards, by means of hydraulic fluid which is pumped into the hydraulic chamber from a second side opposite to the first side, whereby weight is released from the drill bit. It is also conceivable that the force providing unit is configured to be operated in an alternating operating mode, where the normal operating mode and the reverse operating mode alternate, with a specific, variably adjustable frequency. This allows the drilling efficiency to be further increased. In the normal operating mode, it is also conceivable, that weight on bit is reduced by partly or fully release of hydraulic pressure of the hydraulic working medium acting on the double acting piston, due to counterforces which act on the drill bit from the formation to be drilled, e.g. by means of a pressure relief valve of the control unit. In this way, the drill bit can also be protected against overloading and the associated wear, if required. Furthermore, the double acting piston preferably is configured to move a position of the gripping unit. For example, the bottom hole assembly can be anchored in the wellbore at a first position by means of the gripping unit, a predefined section can be drilled, anchoring can be released and the gripping unit can be moved downwards to a second position by means of the double acting piston, the bottom hole assembly can be anchored in the wellbore again at the second position by means of the gripping unit and drilling can be continued. It is also conceivable that the gripping unit can be moved by means of the double acting piston from an initially lower position in the wellbore back up to a higher position, whereby the bottom hole assembly can be anchored in the wellbore again at the higher position by means of the gripping unit, allowing, for example, a pre-drilled section to be refined or enlarged in diameter, or a drilling direction to be changed starting from the higher position in order to produce a further well branch in multi-well drilling applications.

[0024] The invention also relates to a drilling system comprising at least one drilling support device according to one of the embodiments described above and a bottom hole assembly, which comprises at least one drill bit and a drive unit for driving the drill bit. Such a drilling system is distinguished in particular by its advantageous properties in terms of drilling efficiency, which can be achieved by means of the drilling support device. Advantageously the drive unit comprises at least on downhole-drive, which may be embodied as an electrical drive, for example. In the alternative or in addition to an electrical drive, the drive unit may also comprise other types of downhole-drives, e.g. positive displacement pumps or the like. Besides the at least one drilling support device and the bottom hole assembly, the drilling system may comprise other surface or subsurface components. Preferably the drilling system comprises a gear unit, which is configured to generate an impact force on the at least one drill bit. Preferably the gear unit is also configured to increase the torque provided for the at least one drill bit. Preferably the gear unit comprises at least one impact gear and at least one cycloid gear. Preferably, the drilling system, for example, comprises a hoisting unit. The hoisting unit may comprise a drawworks and a wire rope for lowering the bottom hole assembly into the wellbore and hoisting it out of the wellbore. The drawworks may for example be embodied as an electrical winch or any other type of drawworks that appears to be suitable to the person skilled in the art. Preferably, the drilling system comprises a surface control unit for connection to subsurface components of the bottom hole assembly and / or the drilling support device. The surface control unit may be connected at least to the drive unit of the bottom hole assembly and the control unit of the drilling support device. A connection between the surface control unit and the subsurface components could be cable-bound, for example via a cable arranged and protected inside the wire rope of the hoisting unit or via a separate cable. It would also be conceivable to have a wireless connection between the surface control unit and the subsurface components according to any suitable wireless connection standard, such as WIFI or Bluetooth or the like. Preferably, the drilling system comprises an energy supply unit for supplying, in particular electrical, energy to the subsurface components of the drilling system, such as the drive unit. Energy transmission from the energy supply unit to the downhole components may also be cable bound, for example via a cable arranged and protected inside the wire rope of the hoisting unit or via a separate cable. In the alternative or in addition to the energy supply unit, it is also conceivable that the drive unit comprises an energy storage, for example a rechargeable battery, a fuel cell or the like, which is configured for energy supply of the subsurface components of the drilling system. The drilling system is not limited to the components mentioned above and can have other surface components, for example a processing unit for treating drilling fluid, and / or other subsurface components, for example at least one measuring unit for measuring parameters of the drilling system and / or a drilling process, such as torque, rotational speed, weight on bit, drilling depth, pressure and the like. The invention also concerns a method for operating a drilling system, in particular according to the embodiment described above, comprising a drilling support device with a support unit including at least one gripping unit and at least one force providing unit, and a bottom hole assembly including at least one drill bit, the method comprising at least a first step of connecting the drilling support device to the bottom hole assembly, a second step of lowering the bottom hole assembly and the drilling support device into a wellbore, a third step of anchoring the bottom hole assembly in the wellbore by means of the gripping unit and a fourth step of supplying weight on the drill bit by means of the force providing unit enabling drilling of a predefined section. By means of this method for operating the drilling system advantageously an efficient drilling process can be enabled. The fourth step of the method may include drilling of the predefined section by transmitting torque from a drive unit of the bottom hole assembly to the at least one drill bit, wherein drill cuttings generated during drilling of the predefined section may being stored in a drill cuttings storage of the bottom hole assembly. During the fourth step the amount of weight supplied on the drill bit by means of the force providing unit may be varied depending on the drilling conditions. The length of the predefined section to be drilled during the fourth step may vary depending on the capacity of the drill cuttings storage. The length of the predefined section may could be 3 meters, for example, but could also be smaller or longer. The method may comprise additional further steps. The method may comprise an additional further step of releasing the bottom hole assembly from the wellbore, for example by retracting an extendable member of the gripping unit, after drilling of the predefined section. The method may comprise an additional further step of hoisting the bottom hole assembly out of the wellbore and an additional further step of removing drill cuttings from the drill cuttings storage. Subsequently the method may be repeated starting from the second step as often as necessary to reach a desired drilling depth of the wellbore.

[0025] The drilling support device and the drilling system should not be limited to the applications and embodiments described above. In particular, the drilling support device and / or the drilling system may comprise a number of individual elements, components and units other than the number of elements, components and units described herein in order to fulfill a function described herein. In addition to the steps described above, the method for operating the drilling system may include further steps that are carried out preceding, intermediate or subsequent to these steps. Drawings

[0026] Further advantages of the invention become apparent from the following description of the drawings. The drawings show an embodiment of the invention. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will also usefully consider the features individually and combine them to create useful further combinations.

[0027] Brief description of the drawings:

[0028] Fig. 1 a schematic partial view of a drilling system with a drilling support device and a bottom hole assembly, including a drill bit and a drive unit for driving the drill bit,

[0029] Fig. 2 the drilling support device in a schematic perspective view,

[0030] Fig. 3 a schematic front view and a schematic sectional view of a support unit of the drilling support device,

[0031] Fig. 4 a schematic front view and a schematic sectional view of a storage unit and a filtering unit of the drilling support device, and

[0032] Fig. 5 a schematic process flow diagram to illustrate a method for operating the drilling system.

[0033] Fig. 1 shows a schematic partial view of a drilling system 44. The drilling system is configured to perform drilling processes. Without being limited thereto, the drilling system is configured, for example, to perform drilling processes for deep geothermal energy projects. In the present embodiment, the drilling system 44 is configured to perform unconventional discontinuous drilling processes.

[0034] The drilling system comprises a drilling support device 10 and a bottom hole assembly 12. The drilling support device 10 is configured for connection to the bottom hole assembly 12 to be used in a wellbore 14. In Fig. 1 the drilling support device 10 is shown in a connected state with other components of the bottom hole assembly 12 and lowered into the wellbore 14.

[0035] During the drilling process the wellbore 14 is filled with a drilling fluid (not shown). The drilling system 44 is configured for use with any conventional types of drilling fluids, which, depending on the formation to be drilled, can be water-based or oil-based and may comprise a plurality of suitable additives, such as bentonite or barite, for example.

[0036] The bottom hole assembly 12 comprises at least one drill bit 22. In the present embodiment the drill bit 22 is embodied as a core bit. However, it would also be conceivable to use other types of drill bits without departing from the scope of the present invention. In the present embodiment the drilling system 44 comprises a drill cuttings storage 54, which is arranged above the drill bit 22. The drilling system 44 comprises an additional drill bit 56. The additional drill bit 56 is embodied as an underreamer 58. The underreamer 58 is arranged above the drill cuttings storage 54. In comparison to the drill bit 22 the underreamer 58 has a larger outer diameter and is configured to enlarge the initial diameter of the wellbore 14 drilled by the drill bit 22 to the larger outer diameter of the underreamer 58. In the present embodiment the drill bit 22, the drill cuttings storage 54 and the additional drill bit 56 form a drilling unit 60 of the drilling system 44. The drill cuttings storage 54 comprises an opening (not shown) at its top below the underreamer 58. The opening of the drill cuttings storage 54 is provided for receiving drill cuttings generated by the underreamer 58 during the drilling process.

[0037] The drilling system 44 further comprises a drive unit 28 for driving the drill bit 22. In the present embodiment the drive unit 28 is also configured for driving the additional drill bit 56. The drive unit 28 comprises a downhole-drive (not shown). In the present embodiment of the invention the downhole-drive is embodied as an electrical motor. However, it would also be conceivable to use other types of downhole-drives with the drilling system 44, e.g. positive-displacement pumps and the like, without departing from the scope of the present invention. The drive unit 28 comprises a drive shaft 62. The drive shaft 62 is configured to transmit torque generated by the downhole-drive of the drive unit 28 to the drilling unit 60 in order to at least rotate the bit 22 and the additional bit 56. The drilling system 44 further comprises a gear unit 88. The gear unit 88 is configured to generate an impact force, which can be transmitted to the drilling unit 60. A driving torque for driving the gear unit 88 is transmitted from the drive unit 28 to the gear unit 88 via the drive shaft 62. Additionally, the gear unit 88 is also configured to increase torque provided by the drive unit 28. In the present embodiment of the invention, the gear unit 88 is arranged above the drilling unit 60 and the drilling support device 10 in the connected state is arranged in between the gear unit 88 and the drive unit 28. The drive shaft 62 extends from the drive unit 28 through the drilling support device 10 to gear unit 88. However, in the alternative, also other arrangements of the drilling support device 10 would be conceivable, without departing from the scope of the present invention. For example, the drive unit 28 could be arranged directly above the gear unit 88 and the drilling support device 10 could be arranged above the drive unit 28.

[0038] The drilling system 44 comprises a hoisting unit (not shown) for lowering the bottom hole assembly 12 into the wellbore 14 and raising it out of the wellbore 14. The hoisting unit comprises a wire rope 64, which is connected to the bottom hole assembly 12 via an eyelet 66.

[0039] The drilling support device 10 comprises a support unit 16. The support unit 16 includes at least one gripping unit 18. The gripping unit 18 is configured to anchor the bottom hole assembly 12 in the wellbore 14. The support unit 16 further includes at least one force providing unit 20. The force providing unit 20 is configured to supply weight on the drill bit 22 of the bottom hole assembly 12.

[0040] Fig. 2 shows the drilling support device 10 in a schematic perspective view.

[0041] The drilling support device comprises a storage unit 24 for storing a source of energy for the operation of the support unit 16. Without being limited thereto, the gripping unit 18 and / or the force providing unit 20 could be operated electrically, pneumatically or hydraulically, for example. In the present embodiment of the drilling support device 10 the gripping unit 18 and the force providing unit 20 are configured to be operated by the same working medium. In the present embodiment of the invention the gripping unit 18 and the force providing unit 20 are configured to be hydraulically operated.

[0042] The storage unit 24 comprises at least one hydraulic tank 30 for storing a hydraulic working medium (not shown) for the operation of the support unit 16. Without being limited thereto, the hydraulic working medium could be hydraulic oil or water, for example.

[0043] The drilling support device 10 comprises a filtering unit 34, which will be described with more detail in figure 5.

[0044] The Drilling support device 10 comprises a control unit 36 configured to control the gripping unit 18 and the force providing unit 20 independently of one another. The control unit 36 is encased in a tube, which could be manufactured from steel or any other suitable material and which is configured to protect the components of the control unit 36. Figure 2 shows the components of the control unit 36 in highly simplified form with dashed lines.

[0045] The drilling support device 10 comprises a pump 26 to operate the gripping unit 18 and the force providing unit 20. In the present embodiment of the invention, the pump 26 is configured in such a way that it can be driven by the drive unit 28 of the bottom hole assembly 12 which is also intended to drive the drill bit 22 (cf. fig. 1). The pump may for example be embodied as a centrifugal pump. In an operating state of the drilling system 44, a drive torque for driving the pump 26 can be transmitted from the drive unit 28 via the drive shaft 62 (cf. figure 1). In the present embodiment of the invention, the pump is part of the control unit 36. However, it would also be conceivable that the pump 26 is designed as an independent unit separate from the control unit 36.

[0046] The control unit 36 further comprises a hydraulic valve assembly 86. The hydraulic valve assembly 86 comprises a plurality of hydraulic lines and hydraulic valves (not shown). The support unit 16 is connected to the pump 26 via the hydraulic valve assembly. The hydraulic valve assembly 86 is configured such that it allows the gripping unit 18 and the force providing unit 20 the be controlled independently of one another.

[0047] The drilling support device 10 comprises a clutch case 68. The clutch case 68 is arranged above and coupled to the filtering unit 34. The clutch case 68 is configured to receive and support the drive shaft 62 (cf. fig. 5).

[0048] Fig. 3 shows the support unit 16 in schematic front view and in a schematic sectional view.

[0049] The gripping unit 18 comprises at least one extendable member 38 which is configured to anchor the bottom hole assembly 12 in the wellbore 14 (cf. fig. 1). In the present embodiment the extendable member 38 is embodied as an inflatable element 40. The support unit 16 comprises a first hydraulic line 70, which connects the support unit 16 to the control unit 36 (cf. fig. 2). The first hydraulic line 70 is embodied as a feed line of the gripping unit 18 and configured for supplying the gripping unit 18 with hydraulic working medium from the hydraulic tank 30 (cf. fig. 4) by means of the pump 26 (cf. fig. 2). As can be derived from the sectional view of the support unit 16 in fig. 4, the support unit 16 comprises a cylinder pipe 78. The extendable member 38 is arranged around the cylinder pipe 78 in a circumferential direction. In order to anchor the bottom hole assembly 12 in the wellbore 14 (cf. fig. 1), the extendable member 38 can be extended in a radial direction. For this purpose, an intermediate space between the exterior of the cylinder pipe 78 and the extendable member 38 can be filled with hydraulic working medium, which is supplied from the hydraulic tank (cf. fig. 4) via the first hydraulic line 70 by means of the pump 26 (cf. fig. 2). As a result, the extendable member 38, which is embodied as an inflatable element 40, expands and in an expanded position generates a contact pressure against an inner wall of the wellbore 14 (cf. fig. 1), which is strong enough to anchor the bottom hole assembly 12 in a torsion-proof manner, so that torque can be transmitted from the drive unit 28 to the drilling unit 60 (cf. fig. 1) during the drilling process.

[0050] The support unit 16 comprises at least one second hydraulic line 72, which also connects the support unit 16 to the control unit 36 (cf. fig. 2). The second hydraulic line 72 is embodied as a return line of the gripping unit 18 and configured for return of hydraulic working medium from the gripping unit 18 back to the hydraulic tank 30 (cf. fig. 4). In order to release the bottom hole assembly 12 from the wellbore 14 (cf. fig.1 ), hydraulic working medium can be returned from the intermediate space between the exterior of the cylinder pipe 78 and the extendable member 38 via the second hydraulic line 72, which leads to the retraction of the extendable member 38 to its initial position as shown in fig. 3.

[0051] The support unit 16 comprises at least one third hydraulic line 74, which also connects the support unit 16 to the control unit 36. The third hydraulic line 74 is configured to supply the force providing unit 20 with hydraulic working medium from the hydraulic tank 30 (cf. fig. 4) by means of the pump 26 (cf. fig. 2).

[0052] The force providing unit 20 comprises a double acting piston 42. The double acting piston 42 is arranged inside the cylinder pipe 78 and guided by at least one cylinder shaft 80. The force providing unit 20 comprises a cylinder rod 82 which extends through the cylinder pipe 78 and projects above and below it. The double acting piston 42 is connected to the cylinder rod 82. During a normal operating mode of the force providing unit 20, in order to supply weight on the drill bit 22 (cf. fig. 1 ), hydraulic working medium can be pumped from the hydraulic tank 30 (cf. fig. 4) by means of the pump 26 (cf. fig. 2) via the third hydraulic line 74 to a hydraulic chamber 84 inside the cylinder pipe 78. The hydraulic working medium thereby presses the double acting piston 42 and thus the cylinder rod 82 downwards, which thus exerts a force on the drilling unit 60 (cf. fig.1 ). The cylinder rod 82 may be embodied as a hollow tube, allowing the drive shaft 62 (cf. fig. 1) extending therethrough.

[0053] The support unit 16 comprises at least one fourth hydraulic line 76, which also connects the support unit 16 to the control unit 36 (cf. fig. 2). The hydraulic working medium can be returned from the hydraulic chamber 84 back to the hydraulic tank 30 (cf. fig. 4) by means of the fourth hydraulic line 76. It is also possible to operate the force providing unit 20 in a reverse manner. During a reverse operating mode of the force providing unit 20, hydraulic working medium is pumped into the hydraulic chamber 84 via the fourth hydraulic line 76 and can be returned to the hydraulic tank 30 (cf. fig. 4) via the third hydraulic line 74. During the reverse operating mode, the hydraulic working medium presses the double acting piston 42 and thus the cylinder rod 82 upwards, which thus relieves force from the drilling unit 60 (cf. fig.1 ). By means of operating the force providing unit 20 either in normal operating mode or in reverse operating mode, weight on the drill bit 22 (cf. fig. 1 ) can be controlled as needed depending on the drilling conditions. During the normal operating mode, it is also possible that hydraulic pressure of the hydraulic working medium acting on the double acting piston 42 is fully or partially released and a counterforce which acts on the drilling unit 60 from the formation to be drilled is transferred via the cylinder rod 82 on the double acting piston 42, which is pushed upwards as a result, forcing the hydraulic working medium back into the hydraulic tank 60 via the fourth hydraulic line 76.

[0054] Furthermore, the double acting piston 42 is also configured to move a position of the gripping unit 18. For example, the bottom hole assembly 12 (cf. fig. 1 ) can be anchored in the wellbore 14 (cf. fig. 1) at a first position by means of the gripping unit 18, a predefined section can be drilled by means of the drilling unit 60 (cf. fig. 1 ), anchoring can be released by retracting the extendable member 38 of the gripping unit 18. Afterwards the gripping unit 18 can be moved downwards to a second position by means of the double acting piston 42 and the bottom hole assembly 12 can be anchored in the wellbore 14 again at the second position by means of the gripping unit 18 and drilling can be continued. It is also possible for the gripping unit 18 to be moved upwards by means of the double acting piston 42 from an initially lower position in the wellbore 14 back up to a higher position, whereby the bottom hole assembly 12 can be anchored in the wellbore 14 again at the higher position by means of the gripping unit 18. An application case for the gripping unit 18 to be moved up again, could be, for example, to refine a pre-drilled section or increase its diameter, e.g. by means of the underreamer 58 (cf. fig. 1 ).

[0055] Fig. 4 shows a schematic front view and a schematic sectional view of the storage unit 24 and the filtering unit 34 of the drilling support device 10. The storage unit 24 comprises a piston 98. The piston 98 is arranged in the hydraulic tank 30 and guided by at least one cylinder shaft 100. The hydraulic tank 30 comprises at least one opening 32 for pressure compensation. The opening 32 is configured to allow drilling fluid to flow from the wellbore 14 into the hydraulic tank 30 and drilling fluid to flow out of the hydraulic tank 30 into the wellbore 14 (cf. fig. 1 ). When, during the operation of the support unit 16, hydraulic working medium is sucked out of the hydraulic tank 30 by the pump 26 (cf. fig. 2) the piston 98 moves up. Due to the opening 32 drilling fluid can flow from the wellbore 14 into the volume of the hydraulic tank 30 which is generated below the piston 98 during its upward movement. On the other hand, when, during the operation of the support unit 16, hydraulic working medium is pumped back into the hydraulic tank 30 by the pump 26 (cf. fig. 4) the piston 98 moves down and drilling fluid flows back into the wellbore 14 through the at least one opening 32.

[0056] The filtering unit 34 is arranged at the at least one opening 32. The filtering unit 34 is configured to prevent at least larger particles, e.g. drill cuttings generated by the drilling process, from entering the hydraulic tank. In the present embodiment of the invention, the filtering unit 34 comprises a mesh 102 and a further mesh (not shown), which determine the passage diameter of the filtering unit 34 In the present case. Viewed in a flow direction towards the hydraulic tank, the mesh 102 is arranged in front of the further mesh, wherein the mesh 102 has a larger mesh size than the further mesh. In the present embodiment of the invention the mesh 102, for example, has a mesh size of 0.200 mm to retain larger particles and the further mesh has a mesh size of 0.105 mm, for example, to prevent smaller particles from entering the hydraulic tank 30. However, depending on the drilling conditions and the size of the drill cuttings to be expected the mesh 102 and the further mesh may also be replaced by other meshes (not shown) having larger or smaller mesh sizes, without departing from the scope of the invention. In the sectional view of Fig. 4 the clutch case 68 of the drilling support device 10 is shown with the drive shaft 62 supported therein. The clutch case 68 comprises a bearing element 104 by means of which the drive shaft 62 is rotatably supported. In the present case the bearing element 104 is embodied as a rolling bearing, e.g. as a ball bearing. Alternatively, it would also be conceivable, for example, for the bearing element 104 to be embodied as a plain bearing.

[0057] Fig. 5 shows a schematic process flow diagram to illustrate a method for operating the drilling system 44 (cf. fig. 1). The method comprises a plurality of consecutive steps 46, 48, 48, 50, 52. The method comprises at least a first step 46 of connecting the drilling support device 10 to the bottom hole assembly 12, a second step 48 of lowering the bottom hole assembly 12 with the drilling support device 10 into the wellbore 14, e.g. by means of the hoisting unit of the drilling system 44, a third step 50 of anchoring the bottom hole assembly 12 in the wellbore 14 by means of the gripping unit 18 and a fourth step 52 of supplying weight on the drill bit 22 by means of the force providing unit 20 enabling drilling of a predefined section. The fourth step 52 may include drilling of the predefined section, wherein torque is transmitted from the drive unit 28 to the drilling unit 60. During the fourth step 52 weight supplied on the drill bit 22 by the force providing unit 20 may be varied depending on the drilling conditions. Drill cuttings generated during the fourth step 52 are taken up by the drill cuttings storage 54. Depending on the capacity of the drill cuttings storage 54 the length of the predefined section drilled during the fourth step 52 may vary and can for example be 3 meters. In addition, the method may comprise a plurality of additional further steps (not shown in the diagram). The method can comprise an additional further step of releasing the bottom hole assembly 12 from the wellbore, for example by retracting the extendable member 38 of the gripping unit 18. The method can comprise an additional further step of hoisting the bottom hole assembly 12 out of the wellbore and an additional further step of removing the drill cuttings from the drill cuttings storage. Subsequently the method can be repeated again starting at the second step 48. The method may be repeated as often as necessary to reach a desired drilling depth of the wellbore 14. Reference Numerals

[0058] 10 drilling support device

[0059] 12 bottom hole assembly

[0060] 14 wellbore

[0061] 16 support unit

[0062] 18 gripping unit

[0063] 20 force providing unit

[0064] 22 drill bit

[0065] 24 storage unit

[0066] 26 pump

[0067] 28 drive unit

[0068] 30 hydraulic tank

[0069] 32 opening

[0070] 34 filtering unit

[0071] 36 control unit

[0072] 38 extendable member

[0073] 40 inflatable element

[0074] 42 double acting piston

[0075] 44 drilling system

[0076] 46 first step

[0077] 48 second step

[0078] 50 third step

[0079] 52 fourth step

[0080] 54 drill cuttings storage

[0081] 56 additional drill bit

[0082] 58 underreamer

[0083] 60 drilling unit

[0084] 62 drive shaft

[0085] 64 wire rope eyelet clutch case first hydraulic line second hydraulic line third hydraulic line fourth hydraulic line cylinder pipe cylinder shaft cylinder rod hydraulic chamber hydraulic valve assembly gear unit piston cylinder shaft mesh bearing element

Claims

Claims1 . Drilling support device (10) for connection to a bottom hole assembly (12) to be used in a wellbore (14), comprising a support unit (16) including at least one gripping unit (18) configured to anchor the bottom hole assembly (12) in the wellbore (14) and at least one force providing unit (20) configured to supply weight on a drill bit (22) of the bottom hole assembly (12).

2. Drilling support device (10) according to claim 1 , characterized in that the gripping unit (18) and the force providing unit (20) are configured to be operated by the same working medium.

3. Drilling support device (10) according to claim 1 or 2, characterized by a storage unit (24) for storing a source of energy for the operation of the support unit (16).

4. Drilling support device (10) according to any one of the preceding claims, characterized in that the gripping unit (18) and the force providing unit (20) are configured to be hydraulically operated.

5. Drilling support device (10) according to any one of the preceding claims, characterized by a pump (26) to operate the gripping unit (18) and the force providing unit (20).

6. Drilling support device (10) according to claim 5, characterized in that the pump (26) is configured in such a way that it can be driven by a drive unit (28) of the bottom hole assembly (12) which is also intended to drive the drill bit (22).

7. Drilling support device (10) at least according to claims 3 and 4, characterized in that the storage unit (24) comprises at least one hydraulic tank (30) for storing a hydraulic working medium for the operation of the support unit (16).

8. Drilling support device (10) according to claim 7, characterized in that the hydraulic tank (30) comprises at least one opening (32) for pressure compensation, which is configured to allow drilling fluid to flow from the wellbore (14) into the hydraulic tank (30) and drilling fluid to flow out of the hydraulic tank (30) into the wellbore (14).

9. Drilling support device (10) according to claim 8, characterized by a filtering unit (34) arranged at the at least one opening (32) and configured to prevent at least larger particles, e.g. drill cuttings generated by the drilling process, from entering the hydraulic tank (30).

10. Drilling support device (10) according to any one of the preceding claims, characterized by a control unit (36) configured to control the gripping unit (18) and the force providing unit (20) independently of one another.11 . Drilling support device (10) according to any one of the preceding claims, characterized in that the gripping unit (18) comprises at least one extendable member (38) which is configured to anchor the bottom hole assembly (12) in the wellbore.

12. Drilling support device according to claim 11 , characterized in that the extendable member (38) is embodied as an inflatable element (40).

13. Drilling support device (10) according to any of the preceding claims, characterized in that the force providing unit (20) comprises at least one double acting piston (42).

14. Drilling system (44) comprising at least one drilling support device (10) according to any one of the preceding claims and a bottom hole assembly (12), which comprises at least one drill bit (22) and a drive unit (28) for driving the drill bit15. Method for operating a drilling system (44), in particular according to claim 14, comprising a drilling support device (10) with a support unit (16) including at least one gripping unit (18) and at least one force providing unit (20), and a bottom hole assembly (12) including at least one drill bit (22), the method comprising at least a first step (46) of connecting the drilling support device (10) to the bottom hole assembly (12), a second step (48) of lowering the bottom hole assembly (12) with the drilling support device (10) into a wellbore (14), a third step (50) of anchoring the bottom hole assembly (12) in the wellbore (14) by means of the gripping unit (18) and a fourth step (52) of supplying weight on the drill bit (22) by means of the force providing unit (20) enabling drilling of a predefined section.

Images