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Title:
DRILLING SYSTEM FOR THE EXCAVATION OF A WELL AND/OR FOR THE REALISATION IN THE UNDERGROUND OF ONE OR MORE SLOTS TO BE USED AS RADIANT SURFACES FOR THE EXPLOITATION OF THE GEOTHERMAL ENERGY
Document Type and Number:
WIPO Patent Application WO/2013/168189
Kind Code:
A1
Abstract:
The present invention concerns a Drilling system for the excavation of a well and/or for the realisation in the underground of one or more slots to be used as radiant surfaces for the exploitation of the geothermal energy. Said drilling system comprises: at least one drilling arm (1, 1'; 100) to drill the ground along the axial direction of said drilling arm, said drilling arm having a first end and a second end, opposite to said first end, at least one excavating head (10, 10'; 110) having a first end coupled to said first end of said at least one drilling arm (1, 1'; 100), and a second end, opposite to said first end, driving means (25; 140) for driving said excavating head; movable cutting means (2; C1, C2) to cut rock layers in such a way that creating a slot (F) in the underground, and driving means (12; 130, 131, 132, 133, 134, 135, 136) for driving said movable cutting means (2; C1, C2).

Inventors:
CONGIU IGNAZIO (IT)
ISOPO CRISTIAN (IT)
Application Number:
PCT/IT2013/000138
Publication Date:
November 14, 2013
Filing Date:
May 13, 2013
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
CONGIU IGNAZIO (IT)
ISOPO CRISTIAN (IT)
International Classes:
E21B43/26; E21B11/06
Domestic Patent References:
WO2012052496A12012-04-26
Foreign References:
US6688702B12004-02-10
US20110247816A12011-10-13
US20070158072A12007-07-12
Other References:
None
Attorney, Agent or Firm:
FERRIERO, Paolo et al. (Via Piemonte 26, Roma, IT)
Download PDF:
Claims:
CLAIMS

1. Drilling system for the excavation of a well and/or for creating in the underground one or more slots (F) to be used as radiating surfaces for the exploitation of geothermal energy, said drilling system comprising:

- at least one drilling arm (1 , 1'; 100) to drill the ground along the axial direction of said drilling arm, said drilling arm having a first end and a second end, opposite to said first end,

- at least one excavating head (10, 10'; 110) having a first end coupled to said first end of said at least one drilling arm (1 , 1'; 100), and a second end, opposite to said first end,

- driving means (25; 140) for driving said excavating head;

- movable cutting means (2; C1 , C2) to cut rock layers in such a way that creating a slot (F) in the underground, and

- driving means (12; 130, 131 , 132, 133, 134, 135, 136) for driving said movable cutting means (2; C1 , C2).

2. Drilling system according to the previous claim, characterized in that it comprises a first drilling arm (1) and a second drilling arm (1'), a first excavating head (10) and a second excavating head (10'), each of which is coupled to the first end of a respective drilling arm (1 , 1'), in that said driving means (25) are connected to the second end of each drilling arm (1 , 1'), said driving means (25) are also directing means for directing each excavating head (10, 10'), in that said movable cutting means (2) comprise a diamond cable (20) slidably coupled with said first excavating head (10) and with said second excavating head (10'); said diamond cable (20) extending along said drilling arms (1 , 1') and between said drilling arms, and in that said drilling system comprises a pulley (32) disposed on the surface, around which said diamond cable (20) slides; said pulley (32) being movable with respect to the entrance of the well between an initial position, in which the pulley is outside the well, at a first distance from the entrance of the well, said first distance being predetermined, to a final position, in which it is either outside the well at a second distance from the entrance of the well, where said second distance is smaller than said first distance, or inside the well itself;

wherein said drilling arms (1 , 1') and said cutting means (2) cooperate with each other to crush rock layers in such a way that creating said slot (F) in the underground.

3. Drilling system according to the preceding claim, characterized in that each excavating head (10, 10') is provided with a respective pulley (120, 120') for said diamond cable (20), and in that said driving means (12) for said cutting means (2) comprise at least one of said pulleys (120, 120'), where said at least one pulley (120, 120') is a driving pulley; said drilling system preferably comprising two relay pulleys (13, 13'), each of which is arranged on a respective drilling arm (1 , 1').

4. Drilling system according to claim 2 or 3, characterized in that the respective drilling means (11 , 11') are coupled on the second end of each excavating head (10,10'), in that said drilling means (11 , 11') are provided with one or more respective holes or openings (11A, 11Ά) to allow a quantity of water to come out from them and drag the crushed rock debris towards the surface; each drilling arm (1 , 1') having the second end connected to a water pump (30), said water pump (30) pumping water into said drilling arms (1 , 1'), in that each excavating head (10, 10') comprises a hydraulic motor for driving said drilling means (11 , 11').

5. Drilling system according to claim 4, characterized in that said drilling means (11 , 11') are provided with one or more reliefs (11 B); at least one relief (11 B) preferably comprising a piezoelectric transducer or a sonodroto (433).

6. Drilling system according to claim 4 or 5, characterized in that said drilling means (11 , 11') are coupled in a removable manner to the second end of the respective excavating head (10, 10').

7. Drilling system according to any one of claims 2-6, characterized in that each excavating head (10, 10') comprises a respective first part (10A, 10Ά) and a respective second part (10B, 10B'), as well as a respective joint (15,15 ') connecting said two parts.

8. Drilling system according to any one of claims 2-7, characterized in that each excavating head (10, 10') comprises a respective guiding element (16, 16') to keep the excavating head itself in a correct position when the drilling system is in use; each excavating head (10, 10') preferably comprising respective detecting means (14, 14') for determining the position of the excavating head itself.

9. Drilling system according to any one of claims 2-8, characterized in that said diamond cable (20) comprises one or more inserts (20A) disposed on said diamond cable so as to be spaced from each other; at least one insert (20A) preferably comprising a piezoelectric transducer or a sonodroto (43).

10. Drilling system according to claim 1 , characterized in that said movable cutting means (2, C1 , C2) to cut rock layers comprise a first diamond cable (C1) and a second diamond cable (C2), in that said driving means (12, 130, 131 , 132, 133, 134, 135, 136) for driving said movable cutting means (C1 , C2) comprise an articulated quadrilateral (130, 131 , 132, 133, 134, 135, 136), said articulated quadrilateral comprising:

- a first pulleys system (130, 131) for said diamond cables (C1 , C2), each of which can be wound/unwound on a first hook block (139), said first pulley system (130, 131) comprising a first pulley (130) and a second pulley (131), arranged along a first axis (X), each of which rotates about a second axis orthogonal to said first axis (X),

- a guiding element (136) centrally disposed between said first pulley (130) and said second pulley (131),

- a first pair of arms (132, 133) for said first pulley (130) and a second pair of arms (134, 135) for said second pulley (131), where the arms of each pair have a first end pivoted on a respective pulley and the second end slidably pivoted on said guiding element (136) so that said two pulleys (130, 131) move from an initial position, in which the arms of each pair are aligned along a first direction and each arm of the first pair is substantially in contact with a respective arm of the second pair, to a final position, in which each arm of the first pair is aligned with a respective arm of the second pair along a second direction, orthogonal to said first direction, and the arms of each pair are substantially in contact with each other; said drilling system preferably comprising a respective relay pulley (137, 138) for each diamond cable (C1 , C2).

11. Drilling system according to the preceding claim, characterized in that said excavating head (110) comprises:

- a second pulleys system (121 , 122) and a third pulleys system (123,124,125) to allow respectively the sliding of a third diamond cable (C3) and a fourth diamond cable (C4),

wherein said second pulleys system (121 , 122) comprises a first pulley (121) and a second pulley (122), each of which respectively rotates about a first rotation axis (A1) and a second rotation axis (A2), said two axes of rotation being parallel, and said third pulleys system (123, 124, 125) comprises a first pulley (123), a second pulley (124) and a third pulley (125); the first pulley (123) and the third pulley (125) of said third pulleys system (123, 124, 125) rotating about said first rotation axis (A1) in the opposite direction to the rotation direction of the first pulley (121) of the second pulleys system (121 , 122); said first pulley (123) and said third pulley (125) of the third pulleys system (123, 124, 125) being positioned laterally to said first pulley (121) of the second pulleys system (121 , 122), the second pulley (124) of the third pulleys system (123, 124, 125) rotating about a third rotation axis (A3), said third rotation axis being parallel to said first rotation axis (A1) and to said second rotation axis (A2);

- a first pair of hook blocks(RC3, RC3') on which said third diamond cable (C3) can be at least partially wound/unwound, said first pair of hook blocks comprising a first hook block (RC3) and a second hook block (RC3');

- a second pair of hook blocks (RC4, RC4 ') on which said fourth diamond cable (C4) can be at least partially wound/unwound, said second pair of hook blocks comprising a first hook block (RC4) and a second hook block (RC4'),

wherein the first hook block (RC3, RC4) of each pair (RC3, RC3'; RC4, RC4') is movable between an initial position, in which is within the well at a first distance from the entrance of the well, to a final position, in which it is either within the well at a second distance from the entrance of the well, where said second distance is smaller than said first distance, or on the surface at a third distance from the entrance of the well, and said second hook block (RC3 ', RC4') of each pair (RC3, RC3 '; RC4, RC4') is on the surface, at a predetermined distance from the entrance of the well; and

in that

said driving means (25, 140) comprise a hydraulic motor (140) for driving said third diamond cable (C3) and said fourth diamond cable C4);

said first pulley (121) of the second pulleys system (121 , 122) being preferably provided with a circumferential central projection (121 A) which divides it into a first part and a second part, in such a way that the third diamond cable (C3) to wind in an orderly manner on said first pulley (121).

12. Drilling system according to the previous claim, characterized in that said excavating head (110) comprises a first gear wheel (R1), a second gear wheel (R2) on which the second pulley (124) of the third pulleys system (123, 124, 125) is coupled, said second wheel gear (R2) being meshed with said first gear wheel (R1), and a third gear wheel (R3) on which the second pulley (122) of the second pulley system (121,122) is coupled, said third gear wheel (R3) being meshed with said second gear wheel (R2), and in that said hydraulic motor (140) transmits the motion to said first gear wheel (R1) in such a way that the second gear wheel (R2) rotates in the direction opposite to that of said first gear wheel (R1), and that the third gear wheel (R3) rotates in the direction opposite to that of said second gear wheel (R2).

13. Drilling system according to any one of the preceding claims, characterized in that said at least one excavating head (10, 10'; 110) further comprises at least one controlled hydrodynamic cavitation device (29A, 29A', 29B, 29B'; 141) to generate cavitation bubbles, in particular pico- bubbles, nano-bubbles and micro-bubbles.

14. Drilling system according to any one of claims 3-9, characterized in that each excavating head (10, 10') comprises a respective first controlled hydrodynamic cavitation device (29A, 29A') and a respective second controlled hydrodynamic cavitation device (29B, 29B'), in that each first controlled hydrodynamic cavitation device (29A, 29A') is positioned between the first end of the respective excavating head (10, 10') and a point of said excavating head (10, 10') in correspondence of which a respective pulley (120, 120') for the diamond cable (20) is coupled, and each second controlled hydrodynamic cavitation device (29B, 29B') is positioned between said point and the second end of the respective excavating head (10, 10'), and in that a pipe (28) provided with nozzles (28A) connects the first controlled hydrodynamic cavitation device (29A) of the first excavating head (10) to the first controlled hydrodynamic cavitation device (29Α') of the second excavating head (10') in such a way that, when said first controlled hydrodynamic cavitation devices (29A, 29A') are in use, said nozzles (28A) spray cavitation bubbles on the diamond cable (20) and on the rock layers; said pipe (28) comprising at least two rigid tubes connected together by a first connecting element (27) and being connected to each first controlled hydrodynamic cavitation device (29A, 29A') of the excavating heads (10, 10') by means of a respective second connecting element (277, 277'); each second connecting element (277, 277') having one end connected to a respective output of a first controlled hydrodynamic cavitation device (29A, 29A') and the other end connected to said pipe (28), said first connecting element

(27) and said second connecting elements (277, 277') allowing the pipe

(28) to move from a first position, wherein said two rigid tubes are substantially vertical and in contact with each other, to a second position, wherein said two rigid tubes are substantially horizontally aligned.

15. Drilling system according to the preceding claim, characterized in that it comprises one or more hook blocks (40) arranged on the surface, and in that said pipe (28) is connected to said one or more hook blocks (40) by means of one or more cables (41), each of them can be at least partially wound/unwound on said hook blocks (40).

16. Drilling system according to claim 14 or 15, characterized in that each first controlled hydrodynamic cavitation device (29A, 29A') and each second controlled hydrodynamic cavitation device (29B, 29B') comprises a hydrodynamic motor (35), said hydrodynamic motor rotating about its rotation axis (35A), a rotor (36), a stator (37), inside which said rotor is positioned.

17. Drilling system according to claim 16 (when depending from claim 5), characterized in that said second controlled hydrodynamic cavitation device (29B, 29B') further comprises a rotating head (38), integral with the rotor (36), wherein said rotating head (38) is provided with a plurality of injectors (39) to spray cavitation bubbles out through the holes or openings (11 A, 11 A') of the drilling means (11 , 11').

18. Drilling system according to any one of claims 16-17, characterized in that the hydrodynamic motor (35) is within a casing (34), and in that one or more vibrations absorbing magnetic bearings (38) are positioned on said casing (34) for damping the vibrations to which said hydrodynamic motor (35) is subject when the drilling system is in use.

Description:
DRILLING SYSTEM FOR THE EXCAVATION OF A WELL AND/OR FOR THE REALISATION IN THE UNDERGROUND OF ONE OR MORE SLOTS TO BE USED AS RADIANT SURFACES FOR THE EXPLOITATION OF THE GEOTHERMAL ENERGY

The present invention concerns the field of renewable energies, such as geothernnal energy, and makes reference to a drilling system for the excavation of a well and/or for the realisation in the underground of one or more slots to be used as radiant surfaces for the exploitation of the geothermal energy.

In particular, the invention concerns a drilling system allowing to realise a slot in the underground below the bottom of a well. Such a well can be a pre-existing well already excavated in the ground or it can be excavated in the ground by the same drilling system. The depth of the well is chosen as a function of the temperature and/or the mechanical resistance of the rock layer in the underground.

Today, the exploitation of the geothermal energy can be subdivided into two categories:

1. The exploitation of the medium temperature (from 14° to around 18°) of layers located few meters below the surface, which temperature keeps nearly constant during the year; and

2. The exploitation of the high temperature (larger than 100°) of layers located in depth.

In the first case, relevant to the exploitation of medium temperatures, the layers under the earth surface are utilised as heat exchanger for the heat pumps present in conditioning plants.

Conditioning plants of the known type heat up or cool down an ambient, for example a house, upon request of the user depending on the current season.

Such conditioning plants can take as reference temperature the temperature of the external air or that of the ground whereon the house is located.

In the latter case, the conditioning plant must work on a thermal gap that is smaller than that between house and external air. This determines a smaller energy consumption by said conditioning plant.

In order to attain an energy quantity that is sufficient for a medium residence (around 60 m 2 ), an investment is needed, which can be modest if the installation of a heat exchanger in the ground is made during the building construction phase, for example on the bottom of the excavation made to build up the ground work, or it can be significant if the residence has already been constructed and a heat exchanger must be installed, which is of suitable dimensions.

More and more firms offer on the market solutions that are based on the technology of the heat pumps.

In the second case, relevant to the exploitation of high temperatures, it is possible to exploit the heat to produce vapour and drive turbines that can produce electrical energy.

Currently, for the exploitation of the geothermal energy, sites are almost exclusively utilised, which present permeable layers in the underground.

Since the costs to excavate a well can be relevant, mainly due to the fact that some months are necessary to arrive at certain depths, it is necessary to perform pre-emptive researches. Such pre-emptive researches can be performed on surface by suitable machineries, to individuates at certain depths the presence of sufficiently wide layers, which are constituted not by compact rock, rather they are constituted by cobblestones or in any case rock formations that are easily permeable to water.

This because a well excavated exclusively in the compact rock brings the disadvantage that the thermal conductivity of said rock is not very high (for example, the granite has a conductivity equal to 3.5 Kcal/m h °C) and the surface of the well walls, as far as the well is deep (for example, 5 km) is overall of around 2000 m 2 . From this, one derives, by simple calculations of the known type, that the energy that can be extracted from this well is sufficient only for around 15 residences. On the contrary, if one or more permeable layers are present on the bottom of the well, the radiant surface can be considered as remarkably larger in correspondence of said layers.

If the permeable layer is sufficiently wide, a plurality of wells can be realised in such a way that the water can be inputted in one or more of said wells and then the vapour can be extracted from wells different from those wherein the water is inputted.

Indeed, in correspondence of wells on whose bottom a permeable layer finds itself, power stations have been constructed for the exploitation of the thermal energy and/or vapour.

However, the geographical sites where one can excavate to find a permeable layer are very limited.

Currently, excavation techniques are under development, even in the compact rock, which are more rapid and less expensive and could render economic the exploitation of sites with different rock formations.

Today, a technique to increase the radiant surface consists in the realisation of a well, by excavating in the ground till a desired depth, filling said well with water, and exert pressure on to said water by means of known type in such a way that on the bottom of the well one or more fractures are created.

However, the fractures with such technique can be mutually non- communicating. In such a case, it is necessary to excavate further wells, in an intermediate position with respect to those created or planned, and to create further fractures that are communicating with the previous fractures.

Another technique is that of utilising explosives that are made firing on the bottom of a well to increase the radiant surface.

This brings the disadvantage of excavating necessarily further wells with corresponding high costs.

It is object of the present invention to overcome said disadvantages, providing a drilling system for the excavation of a well and/or for the realisation in the underground of one or more slots to be used as radiant surfaces for the exploitation of the geothermal energy. It is subject-matter of the present invention a drilling system for the excavation of a well and/or for creating in the underground one or more slots to be used as radiating surfaces for the exploitation of geothermal energy, said drilling system comprising:

- at least one drilling arm to drill the ground along the axial direction of said drilling arm, said drilling arm having a first end and a second end, opposite to said first end,

- at least one excavating head having a first end coupled to said first end of said at least one drilling arm, and a second end, opposite to said first end,

- driving means for driving said excavating head;

- movable cutting means to cut rock layers in such a way that creating a slot in the underground, and

- driving means for driving said movable cutting means.

In a first configuration, said drilling system may comprise a first drilling arm and a second drilling arm, a first excavating head and a second excavating head, each of which is coupled to the first end of a respective drilling arm. In particular, said driving means may be connected to the second end of each drilling arm, and may be also directing means for directing each excavating head. The movable cutting means may comprise a diamond cable slidably coupled with said first excavating head and with said second excavating head, and said diamond cable may extend along said drilling arms and between said drilling arms. Moreover, said drilling system may comprise a pulley disposed on the surface, around which said diamond cable slides, and said pulley may be movable with respect to the entrance of the well between an initial position, in which the pulley is outside the well, at a first distance from the entrance of the well, said first distance being predetermined, to a final position, in which it is either outside the well at a second distance from the entrance of the well, where said second distance is smaller than said first distance, or inside the well itself. In such a first embodiment, the drilling arms and the cutting means cooperate with each other to crush rock layers in such a way to creating said slot in the underground.

According to the invention, each excavating head may be provided with a respective pulley for said diamond cable, and said driving means for said cutting means may comprise at least one of said pulleys, where said at least one pulley is a driving pulley. It is preferable that said drilling system comprises two relay pulleys, each of which is arranged on a respective drilling arm.

Still according to the invention, respective drilling means may be coupled on the second end of each excavating head, and said drilling means are provided with one or more respective holes or openings to allow a quantity of water to come out from them and drag the crushed rock debris towards the surface. Each drilling arm may have the second end connected to a water pump, wherein said water pump pumps water into said drilling arms, and each excavating head may comprise a hydraulic motor for driving said drilling means.

It is preferable that said drilling means are provided with one or more reliefs; and it is still more preferable that at least one relief comprises a piezoelectric transducer or a sonodroto.

Advantageously, said drilling means may be coupled in a removable manner to the second end of the respective excavating head.

Still advantageously, each excavating head may comprise a respective first part and a respective second part, as well as a respective joint connecting said two parts.

Moreover, each excavating head may comprise a respective guiding element to keep the excavating head itself in a correct position when the drilling system is in use, and preferably respective detecting means for determining the position of the excavating head itself.

In particular, said diamond cable may comprise one or more inserts disposed on said diamond cable so as to be spaced from each other, and at least one insert may preferably comprise a piezoelectric transducer or a sonodroto.

In a further configuration, said movable cutting means to cut rock layers may comprise a first diamond cable and a second diamond cable, and said driving means for driving said movable cutting means may comprise an articulated quadrilateral comprising:

- a first pulleys system for said diamond cables, each of which can be wound/unwound on a first hook block, said first pulley system comprising a first pulley and a second pulley, arranged along a first axis, each of which rotates about a second axis orthogonal to said first axis,

- a guiding element centrally disposed between said first pulley and said second pulley,

- a first pair of arms for said first pulley and a second pair of arms for said second pulley, where the arms of each pair have a first end pivoted on a respective pulley and the second end slidably pivoted on said guiding element so that said two pulleys move from an initial position, in which the arms of each pair are aligned along a first direction and each arm of the first pair is substantially in contact with a respective arm of the second pair, to a final position, in which each arm of the first pair is aligned with a respective arm of the second pair along a second direction, orthogonal to said first direction, and the arms of each pair are substantially in contact with each other.

It is moreover preferable that said drilling system comprises a respective relay pulley for each diamond cable.

According to the invention, in such a further configuration, said excavating head may comprise:

- a second pulleys system and a third pulleys system to allow respectively the sliding of a third diamond cable and a fourth diamond cable,

wherein said second pulleys system comprises a first pulley and a second pulley, each of which respectively rotates about a first rotation axis and a second rotation axis, said two axes of rotation being parallel, and said third pulleys system comprises a first pulley, a second pulley and a third pulley; the first pulley and the third pulley of said third pulleys system rotating about said first rotation axis in the opposite direction to the rotation direction of the first pulley of the second pulleys system; said first pulley and said third pulley of the third pulleys system being positioned laterally to said first pulley of the second pulleys system, the second pulley of the third pulleys system rotating about a third rotation axis, said third rotation axis being parallel to said first rotation axis and to said second rotation axis;

- a first pair of hook blocks on which said third diamond cable can be at least partially wound/unwound, comprising a first hook block and a second hook block;

- a second pair of hook blocks on which said fourth diamond cable can be at least partially wound/unwound, comprising a first hook block and a second hook block,

wherein the first hook block of each pair is movable between an initial position, in which is within the well at a first distance from the entrance of the well, to a final position, in which it is either within the well at a second distance from the entrance of the well, where said second distance is smaller than said first distance, or on the surface at a third distance from the entrance of the well, and said second hook block of each pair is on the surface, at a predetermined distance from the entrance of the well.

Moreover, said driving means may comprise a hydraulic motor for driving said third diamond cable and said fourth diamond cable, and said first pulley of the second pulleys system is preferably provided with a circumferential central projection which divides it into a first part and a second part, in such a way that the third diamond cable to wind in an orderly manner on said first pulley.

In particular, the excavating head may comprise a first gear wheel, a second gear wheel on which the second pulley of the third pulleys system is coupled, said second wheel gear being meshed with said first gear wheel, and a third gear wheel on which the second pulley of the second pulley system is coupled, said third gear wheel being meshed with said second gear wheel, and said hydraulic motor may transmit the motion to said first gear wheel in such a way that the second gear wheel rotates in the direction opposite to that of said first gear wheel, and that the third gear wheel rotates in the direction opposite to that of said second gear wheel.

According to the invention, both in the first configuration and in the further configuration above mentioned, said at least one excavating head may further comprise at least one controlled hydrodynamic cavitation device to generate cavitation bubbles, in particular pico- bubbles, nano- bubbles and micro-bubbles.

With reference to the first configuration, each excavating head may comprise a respective first controlled hydrodynamic cavitation device and a respective second controlled hydrodynamic cavitation device, and each first controlled hydrodynamic cavitation device is positioned between the first end of the respective excavating head and a point of said excavating head in correspondence of which a respective pulley for the diamond cable is coupled, and each second controlled hydrodynamic cavitation device is positioned between said point and the second end of the respective excavating head. Moreover, a pipe provided with nozzles may connect the first controlled hydrodynamic cavitation device of the first excavating head to the first controlled hydrodynamic cavitation device of the second excavating head in such a way that, when said first controlled hydrodynamic cavitation devices are in use, said nozzles spray cavitation bubbles on the diamond cable and on the rock layers. In particular, said pipe may comprise at least two rigid tubes connected together by a first connecting element and be connected to each first controlled hydrodynamic cavitation device of the excavating heads by means of a respective second connecting element. Each second connecting element has one end connected to a respective output of a first controlled hydrodynamic cavitation device and the other end connected to said pipe. Said first connecting element and said second connecting elements allow the pipe to move from a first position, wherein said two rigid tubes are substantially vertical and in contact with each other, to a second position, wherein said two rigid tubes are substantially horizontally aligned.

Advantageously, the drilling system may comprise one or more hook blocks arranged on the surface, and said pipe may be connected to said one or more hook blocks by means of one or more cables, each of them being at least partially wound/unwound on said hook blocks.

According to the invention, each first controlled hydrodynamic cavitation device and each second controlled hydrodynamic cavitation device may comprise a hydrodynamic motor, rotating about its rotation axis, a rotor, a stator, inside which said rotor is positioned.

In particular, said second controlled hydrodynamic cavitation device may further comprises a rotating head, integral with the rotor, wherein said rotating head is provided with a plurality of injectors to spray cavitation bubbles out through the holes or openings of the drilling means.

Further, according to the invention, the hydrodynamic motor may be within a casing, and one or more vibrations absorbing magnetic bearings may be positioned on said casing for damping the vibrations to which said hydrodynamic motor is subject when the drilling system is in use.

The present invention will be no described by way of illustration but not by way of limitation according to its embodiments, with particular reference to the figures of the enclosed drawings, wherein:

figure 1 shows diagrammatically the drilling system for the realisation of radiant surfaces in the underground, which is subject matter of the invention, inserted in a well already excavated in the underground; figure 2 shows a particular relevant to a excavation head of a drilling arm of the drilling system according to figure 1 ;

figure 3 shows diagrammatically a slot of substantially triangular form, excavated in the underground by means of the drilling system of figure 1;

figure 4 shows diagrammatically the slot of figure 3, wherein tubes have been inserted for the transportation and injection of water in such a slot to the end of generating vapour, and a further conduit to collect and transport on the surface such a vapour, inserted at least partially in the well;

figures 5-6 shows diagrammatically the excavation heads of the drilling arms respectively in a first position, wherein they are diverging, and in the second position, wherein they are converging;

figure 7 shows diagrammatically a slot of substantially rhombic form excavated in the underground by means of the excavation system of figure 1 ;

figure 8 shows diagrammatically the slot of figure 7, in which tubes have been inserted to transport and inject water in such a slot for the generation of vapour, and a further conduit to collect such a vapour inserted at least partially in the well;

figure 9 shows partially a second embodiment of the drilling system, wherein each excavation head is provided with the first and second device of controlled hydrodynamic cavitation for generating cavitation bubbles; figure 10 is a perspective view of a portion of diamond cable of the drilling system of figure 9, which diamond cable is provided with inserts; figure 11 shows the cavitation bubbles between the inserts of the diamond cable and the rock layer;

figure 12 shows the evolution of a cavitation bubble from its generation to its implosion;

Figures 13-14 show respectively small rock debris that are attracted by cavitation bubbles, and larger rock debris that attract cavitation bubbles;

figure 15 shows a variation of the diamond cable of figure 10, wherein the inserts of the diamond cable are provided with piezoelectric transducer or sonodroto;

figure 16 shows diagrammatically the first device of controlled hydrodynamic cavitation that is present in the excavation head;

figure 17 shows diagrammatically the second device of controlled hydrodynamic cavitation that is present in the excavation head; figure 18 is a view from below of the excavation means provided on the excavation head;

figure 19 shows a third embodiment of the drilling system is comprising a drilling arm;

figures 20-22 show a pulleys system for the two diamond cables of the drilling system of figure 19, by which a slot is created in the underground, in a position that is respectively initial, intermediate, and final;

figure 23 shows diagrammatically how the two diamond cables run with respect to the pulleys system of figure 22;

figure 24 shows a detail of the third embodiment of figure 19, relevant to the excavation head, comprising two pulleys systems for a respective diamond cable, by means of which the ground is drilled;

figure 25 shows the same detail of figure 24 wherein the rotating pulleys on a same rotation axis are spaced apart, for a better understanding of the functioning of the two pulleys systems;

figure 26 shows further the detail of the excavation head, comprising the two pulleys systems;

figure 27 shows diagrammatically how the hydraulic motor transmits the motion to the third diamond cable and to the fourth diamond cable of the excavation system of figure 19;

figure 28 shows diagrammatically, in correspondence to an excavation plant, a slot of substantially triangular form excavated in the underground;

figures 29-30 shows diagrammatically in correspondence of an excavation plant a slot of substantially rhombic form excavated in the underground, and a plurality of slots of substantially rhombic form excavated in the underground.

With particular reference to figure 1 , a drilling system is provided for the realisation of a radiant surface in the underground, below the bottom of a well.

In the first embodiment here described, the drilling system is inserted in a pre-existing well. However, said well can be excavated by the drilling system itself.

Such a drilling system comprises:

- a first drilling arm 1 and a second drilling arm V to drill the ground along the axial direction of each arm, each of them presenting a first end provided with a respective excavation had 10, 10', and a second end, opposite to said first end,

- cutting means 2 to cut the rock layer between said two drilling arms.

In particular, said the cutting means 2 comprise a diamond cable 20 extending along said drilling arms 1 , 1', and between said drilling arms, from an excavation head to the other, so that said drilling arms 1 , 1' are connected with each other by said diamond cable.

The drilling system comprises moreover driving and directioning means 25 of the excavation heads to drive the excavation heads 10, 10' and direct them in the underground, connected to the second ends of said drilling arms 1 , 1' , and driving means 12 to try said cutting means 2. In the example here illustrated, said driving an directioning means 25 of the excavation heads 10, 10' are means of the electric type, and comprise an electric motor that is connected to each excavation head 10, 10' by means of a respective electric cable (not shown). However, said driving and directioning means 25 can be of the hydraulic type, and comprise a hydraulic motor, without for this reason falling outside the scope of the invention.

The drilling arms 1 , 1' and cutting means 2 cooperate to drill the ground in such a way to excavate a slot F in the underground.

In particular, each excavation head 10, 10' has a first end connected to a drilling arm and a second end on which respective drilling means in 11 , 11' are provided. Said drilling means 11 , 11' can be coupled/decoupled to the excavation heads. This allows to easily remove said drilling means for their substitution. Moreover, the fact that said drilling means 11 , 11' can be removed from the respective excavation heads 10, 10' allows said excavation heads not to necessarily include the presence of said drilling means, for example when the cavities have been already excavated by a drilling arm.

Each excavation head 10, 10' comprises a respective first part 10A, 10Ά and a respective second part 10B, 10B', as well as the respective joints 15, 15' connecting said two parts.

At the end of each first part 10A of the excavation heads 10, 10' drilling means 11 , 11' are provided. The latter are provided with one or more respective holes or openings 11A, 11Ά to allow to a water quantity to be discharged from them and drag towards the surface the rock debris of the rock layers that have been crashed with the passage of the drilling arms 1 , 1' (figure 2). The water is pumped within the drilling arms 1 , 1' by a pump 30 external to the drilling system, and connected to them.

As one can see from figure 2, each excavation head 10, 10' comprises a respective guiding element 16, 16' to maintain the excavation head in the correct position when the slot F is excavated. Said guiding element is a wing protruding from the respective excavation head in such a way that, when the slot F is excavated, the free end of said wing is within such a slot. Each excavation head 10, 10' comprises further respective detection means 14, 14' to determine the position of the same excavation head. Such detection means can be sensors of the sonar or radio waves type.

Each excavation head 10, 10' comprises a hydraulic motor (not shown) for the driving of said drilling means 11, 11', which can be of the turbine or lobes type. Said hydraulic motor is driven by the same water that is pumped within the drilling arms 1 , 1' by means of the pump 30.

The movement of a drilling arm is independent from the movement of the other arm. In the example here described, the drilling arms are brought down in the well close to one another, and in the bottom of the well they are made diverging in such a way that an angle is created between them to create a slot. However, the drilling arms can be inserted in the well even if they are already diverging, when the dimensions of the well allows it.

Each excavation head 10, 10' comprises an electronic central unit that, in connection with a data elaboration unit (not shown) on the surface, allows an operator to monitor and control the excavation parameters, such as for example position, temperature, pressure, humidity, excavation speed, acceleration. In such a way, the operator can monitor the movements of the excavation heads 10, 10' with respect to a longitudinal axis passing for the centre of the well, so as to control in a constant way their position and that of the diamond cable 20. A constant tension of the diamond cable maximises the effect of the cutting of the rock material.

As an alternative, it is possible to control the movements of the excavation heads 10, 10' by analysing the excavation speed of the excavation heads and running speed of the diamond cable 20 by means of geometrical calculations.

The driving means of the diamond cable 20 comprise two driving pulleys 120, 120', each provided on the second part 10B, 10'B of the respective excavation head 10, 10'. However, in order to drive the cutting means 2, it is sufficient that one of said pulleys be a driving pulley, without for this reason falling outside the scope of the invention.

Said driving pulleys 120, 120' are driven by the same hydraulic motor that drives the drilling means 11 of the same excavation head 10 and is provided of diamond cable 20 tension control means for the control of the tension of the diamond cable 20 (not shown in the figure) at any time, which extend or shorten progressively the portion of diamond cable 20 between the two pulleys. For example, said tension control means may comprise a lever having an end integral with an excavation head and an end in contact with the diamond cable 20.

The drilling system comprises further pulleys: a further pulley 32 on the surface to allow the diamond cable 20 to keep taut, and two further pulleys 13, 13', each disposed in the underground in correspondence to the bottom of the well. Said further pulley 32 is movable with respect to the entrance of the well between an initial position, wherein it is external to the well, at the first predetermined distance from the entrance of the well, to a final position, wherein it is either external to the well, at the second distance from the entrance of the well, which second distance is smaller than said first predetermined distance, or within the well itself. In other words, said further pulley approaches or goes off from the entrance of the well, as a function of the depth reached by the excavation heads 10, 10', i.e. depending on whether the diamond cable 20 is respectively made going down in the underground or going up. In its initial position, said further pulley 32 is kept by support means (not shown), as for example a winch.

In figure 1 , the drilling arms 1 , 1' have been pulled apart in such a way to form a determined angle between them so that in the underground a slot is formed with substantially triangular section, wherein the inclined sides of said triangular section correspond to the cavities excavated by the drilling arms 1 , 1' , and the base of said section corresponds to the cavity excavated by the cutting means 2.

In figure 3, the slot with substantially triangular section is diagrammatically shown, which has been excavated in the underground by means of the drilling system.

In particular, once created the slot in the underground, the drilling system is removed and tubes 23 are inserted, which have a length equal to the length of the cavity excavated by the drilling arms 1 , 1' wherein they are inserted, to transport and inject water in such a slot so that, from the contact of the water with the rock layers of the slot, vapour is generated, which is collected on the surface. To this end, an insulated vapour collection conduit 18 is inserted at least partially in the well (figure 4) to allow the vapour to be canalised towards the surface. In particular, the tubes 23 for the transportation and injection of water have a first end or upper end connected to a water pump and a second end or lower end at which a plurality of tubes 233 are fixed by means of a corresponding connecting element 234, each of which is provided with nozzles 233A to inject water in the slot F. In the example here described, also the tubes 23 are provided with nozzles 23A to inject water in the slot F.

With reference to figures 5 and 6, the excavation heads 10, 10' are shown for each drilling arms 1, 1" that respectively begin to converge and that converge towards a common point.

When the two drilling arms 1 , 1" converge towards a common point, the diamond cable 20 is passed from the first triangular configuration, wherein the lateral portions of the cable extend along the drilling arms, to a second triangular configuration, wherein the latter portions extend in the zone comprised between the two drilling arms.

When the drilling arms are made converging, the slot F passes from a substantially triangular form to a substantially rhombic form (figure 7).

Once such a slot is created in the underground, the drilling system is removed and tubes 23 are inserted to transport water and inject it in such a slot by means of the nozzles 23A (figure 8), so that the vapour, generated by the contact of the injected water with the rock layer of the slot, is collective on the surface by means of a collection conduit.

In a second embodiment of the drilling system shown on figure 9, each excavation head 10, 10' comprises inside itself a respective first controlled hydrodynamic cavitation device 29A, 29A' and a respective second controlled hydrodynamic cavitation device 29B, 29B' to generate cavitation bubbles, in particular, micro-, nano-, an pico-bubbles. By this embodiment, the rock material is crashed by the combined action of the diamond cable 20 and the cavitation bubbles.

With reference to the excavation heads 10, 10', the first hydrodynamic cavitation device 29A, 29A' is positioned between the first end of the respective excavation head 10, 10' and a point of the same excavation head in correspondence of which the driving pulley 120, 120' for the diamond cable 20 is fixed, and the second hydrodynamic cavitation device 29B, 29B' is positioned between said point and the second end of the respective excavation head.

The first hydrodynamic cavitation device 29A of the excavation head 10 of the first drilling arm 1 is connected to the first hydrodynamic cavitation device 29A' of the excavation head 10' of the second drilling arm 1', by means of a pipe 28 provided with nozzles 28A to inject said cavitation bubbles in the slot. Such pipe 28 comprises at least two rigid tubes connected with each other by means of a first connecting element 27, and is connected to each first controlled hydrodynamic cavitation device 29A, 29A' of the excavation heads 10, 10' by means of a respective second connecting element 277, 277' having an end connected to the exit of each first controlled hydrodynamic cavitation device 29A, 29A' and the other end connected to said pipe 28. Said first connecting element 27 and said second connecting elements 277, 277' allow said pipe 28 to pass from a first position, wherein said two rigid tubes are substantially vertical and in contact with each other, to a second position, wherein said two rigid tubes are substantially horizontally aligned.

Moreover, said pipe 28 is connected to one or more hook blocks 40 on the surface by means of one or more cable 41 , that can be wound/unwound on said hook blocks, so as to avoid a possible contact between said pipe 28 and said diamond cable 20.

The cutting means 2 comprise, besides the diamond cable 20, a plurality of inserts 20A disposed on the diamond cable itself and spaced apart with respect to one another (figure 10). Said inserts 20A exert a pressure on the cavitation bubbles to such an extent that the bubbles implodes (figure 11).

Figure 12 shows diagrammatically the evolution of a cavitation bubble from its formation to its implosion. The implosion makes it possible that a localised energy is released under the form of Shockwaves. The collapse of such cavitation bubbles produces an intense local heating up, high-pressures, as well as other supersonic cavitating jets. The latter exploit the possibility to create cavitation phenomena generating in the liquid vapour bubbles that, imploding, generate very high pressure impulses. The rock debris that are formed as a consequence of the action of the drilling arms 1 , 1' and the diamond cable 20 can have different dimensions. Independently from their dimensions, such rock debris are dragged to the surface by the cavitation bubbles that dispose around the rock debris and drag it upwards.

In particular, in figure 13 small dimensions rock debris are shown, of the order of magnitude of the nanometre and picometre, that are attracted by the cavitation bubbles and dragged towards the surface, and in figure 14 rock debris are shown with greater dimensions, of the order of magnitude of the micrometre and nanometre, which attract the cavitation bubbles, and are dragged towards the surface.

In a variation shown in figure 15, each insert 20A of the diamond cable 20 comprises a piezoelectric transducer or sonodroto 43 for the generation of ultrasounds vibrations that are transmitted to said diamond cable 20 through the excavation head. This allows the diamond cable 22 function both as mechanical means to wear away the rock material and as lithotripter means of the rock material, i.e. as source of high-intensity mechanical waves.

Each control hydrodynamic cavitation device comprises a hydrodynamic motor 35 driven by the water pumped by the pump 30 within the respective excavation head, rotating around its rotation axis 35A, a rotor 36, a stator 37 inside which said rotor is positioned.

In particular, each first controlled hydrodynamic cavitation device

29A, 29A' generates cavitation bubbles that are sent within the pipe 28 and injected by means of the nozzles 28A on the portion of diamond cable 20 comprised between the two drilling arms 1, 1' (figure 16).

Each second controlled hydrodynamic cavitation device 29B, 29B' comprises further a rotating head 38, integral with the rotor 36, provided with a plurality of injectors 39 to inject cavitation bubbles outside through the openings in 11A provided on the drilling means 11 (figure 17).

In particular, the hydrodynamic motor 35 is within a casing 34 and, on said casing, vibrations absorbing magnetic bearings 38 are provided to absorb the vibrations undergone by the motor 35 and due to the crashing of the rock material during the excavation.

In the second embodiment here described, the drilling means 11 , 11' present a plurality of reliefs 11 B that are shaped in such a way to form four petals (figure 18).

Said reliefs 11 B are realised with materials suitable to the abrasive and hard conditions, as for example the tungsten carbide and/or with a sintered matrix coated by polycrystalline synthetic diamond or diamond, and this allows the speeding up of the progression and the longer duration also in the crashing of the most difficult and abrasive layers.

In particular, each relief 11 B comprises a plurality of piezoelectric or sonodroto transducers 433, so that the rock layers undergo the action of the excavation means provided with reliefs incorporating said piezoelectric transducers and the action of the cutting means, optimised by the generation of the cavitation bubbles.

The second embodiment has the advantage that the drilling system subject matter of the invention can be utilised to excavate petrol wells, or to transform existing petrol wells with residual crude oil or nonconventional crude oil, gasifying it by the micro-bubbles, nano-bubbles, and pico- bubbles generated by the hydrodynamic cavitation device that are present in the excavation heads.

Advantageously, the nozzles provided for the injection of such cavitation bubbles are able to increase the flow speed so that a greater production of cavitation bubbles is obtained and the excavation phase is speeded up.

In the case where the drilling system is utilised for the excavation of petrol wells, even a possible phase of hydrocarbon conversion till exhaustion can be speeded up.

With reference to figures 19-26, in the third embodiment here described, one provides the drilling system, comprising a drilling arm 100 to drill the ground.

With particular reference to figures 19-22, for the creation of the last in the underground, the excavation system comprises an articulated quadrilateral to allow the sliding of a first diamond cable C1 and a second diamond cable C2, each of which can be wound/unwound on a first hook block 139.

Said articulated quadrilateral comprises a first pulleys system, which comprises a first pulley 130 and a second pulley another 31, disposed along a first axis X, each of which rotates on a second axis orthogonal to said first axis.

Said articulated quadrilateral further comprises:

a guiding element 136 disposed centrally between said first pulley 130 and said second pulley 131,

a first arms pair 132, 133, for said first pulley 30 and a second arms pair 134, 135 for said second pulley 131 , wherein the arms of each pair have a first end pivoted on a respective pulley and the second end slidably pivoted on said guiding element 136, in such a way that said two pulleys 130, 131 pass from an initial position, wherein the arms of each pair are aligned along a first direction and each arm of the first pair is substantially in contact with a respective arm of the second pair (figure 20), to a final position, wherein each arm of the first pair is aligned to a respective arm of the second pair along a second direction, orthogonal to said first direction, and the arms of each pair are substantially in contact with each other (figure 22).

In an intermediate position between the initial and the final position, the arms of each pair are inclined with respect to said guiding element 136, forming an angle with it (figure 21).

For each diamond cable C1 , C2, a respective relay pulley 137, 138 is provided as shown in figure 23, showing how each diamond cable C1 and C2 slides with respect to said pulleys system.

The first diamond cable C1, that goes down from the first hook block 139, runs along first the relay pulley 137 and then the first pulley 130 winds partially on a second hook block 139' and finally goes up again towards the first hook block 139.

Analogously, the second diamond cable C2, which goes down from the hook block 139, first runs along the relay pulley 138, and then along the second pulley 131 , it winds partially on the second hook block 139' and finally goes up again towards the first hook block 139.

According said third embodiment, with reference to figures 24-26, the drilling system comprises a second pulleys system and a third pulleys system, comprised in the excavation head 110, to allow the sliding respectively of a third diamond cable C3 and a fourth diamond cable C4, each of which can be wound/unwound respectively on the first pair of hook blocks RC3, RC3', and on a second pair of hook blocks RC4, RC4', and is driven by a hydraulic motor 140.

Each pair of hook blocks comprises a first hook block RC3, RC4 and a second hook block RC3', RC4', wherein the first hook block of each pair RC3, RC4 is movable, as a function of the depth reached by the excavation head 110, between an initial position, wherein it is within the well, at a first distance from the entrance of the well, to a final position, wherein it is either within the well, at the second distance from the entrance of the well, smaller than said first distance, or on the surface, at a third distance from the entrance of the well. On the other hand, the second hook block RC3', RC4' of each pair is on the surface, at the predetermined distance from the entrance of the well.

The second pulleys system comprises a first pulley 121 , and a second pulley 122, each of which rotates respectively around a first rotation axis A1 and a second rotation axis A2, wherein said two rotation axes are parallel (figure 24).

When put into rotation by the hydraulic motor 140, the third diamond cable C3, that goes down from the first pair of hook blocks RC3 and RC3', winds partially on said first pulley 121 , goes up towards the second pulley 122, winds partially on said second pulley, goes down further on said first pulley 121 , winds partially on said first pulley, and finally goes up towards said first pair of hook blocks RC3, RC3' (figure 25).

In particular, the first pulley 121 is subdivided into a first part and the second part by a circumferential central protrusion 121 A in such a way that, when the third diamond cable C3 winds up partially on said first pulley 121 for the first time and for the second time, it is in contact respectively with the first part and the second part.

The third pulleys system comprises a first pulley 123, a second pulley 124 and the third pulley 125 (figures 24-26).

The first pulley 123, and the third pulley 125 of the third pulleys system rotates on the first rotation axis A1 , in a direction opposite to the rotation direction of the first pulley 121 , of the second pulleys system, and are positioned at the sides of the latter.

The second pulley 124 rotates around a third rotation axis A3, which is parallel to the first rotation axis A1 and to the second rotation axis A2.

When put into rotation by the hydraulic motor 140, the fourth diamond cable C4, which goes down from the second pair of hook blocks RC4 and RC4', winds partially on said first pulley 123, goes up towards the second pulley 124, it winds partially on said second pulley, goes down on said third pulley 125, winds partially on said third pulley, and finally goes up again towards the second pair of hook blocks RC4, RC4' (figure 25).

The first pulley 121 and the second pulley 122 of the second pulleys system and the second pulley 124 of the third pulleys system are positioned between two plates P1 and P2 parallel and fixed on the bottom of the casing of the hydraulic motor 140 (figure 26).

With reference to the transmission of the motion from the hydraulic motor 142 to the second pulleys system and the third pulleys system, said hydraulic motor 140 can transmit the motion to a first gear wheel R1 that meshes with a second gear wheel R2, whereon the second pulley 124 of the third pulleys system is provided, and in turn the second gear wheel R2 meshes with a third gear wheel R3 whereon the second pulley 122 of the second pulleys system is provided (figure 27). The module transmits the motion to the first gear wheel R1 in such a way that the second gear wheel R2 rotates in the direction opposite to that of the first gear wheel R1 and that the third gear wheel R3 rotates in the direction opposite to that of the second gear wheel R2, i.e. in the same direction of the first gear wheel R1.

Moreover, the excavation head 110 comprises a controlled hydrodynamic cavitation device 141 for the generation of cavitation bubbles in such a way to facilitate the excavation.

An advantage is given by the fact that in case of planned substitution or possible breaking of the diamond cable, its substitution allows time saving, since not excavation array must be extracted.

Advantageously, by means of such drilling system, it is possible tomorrow to the state of each diamond cable.

Finality, in the figures 28, 29, 31 or more slots are shown, which have been excavated in the underground in correspondence of a drilling plant.

Figures 28 and 29 show a slot excavated in the underground and having a form which is respectively substantially triangular and substantially rhombic, whilst figure 30 shows a plurality of slots excavated in the underground and having substantially rhombic form.

Advantageously, as already mentioned, independently from the embodiment, by the system of the present invention it is possible to obtain a radiant surface in the underground at the end of a well for the exploitation of the geothermal energy by the creation of one or more slots in the underground.

Finally, advantageously, possible chalky formations within the slot excavated in the underground may be easily removed, first by extracting the water discharge pipes and vapour return pipes, introduced after having excavated the slot and remove the drilling system, and then by using again the drilling system to restore the transmittance of the slot walls.

The present invention has been described by way of illustration but not by way of limitation, according to its preferred embodiments, but it is to be understood that variation and/or changes may be effected by those skilled in the art without so departing from the relevant scope of protection, as defined by the annexed claims.