WO2011154984A2 - Process for creating artifical permeable layers in substrate for exploitation of geothermal energy - Google Patents

Process for creating artifical permeable layers in substrate for exploitation of geothermal energy Download PDF

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Publication number
WO2011154984A2
WO2011154984A2 PCT/IT2011/000194 IT2011000194W WO2011154984A2 WO 2011154984 A2 WO2011154984 A2 WO 2011154984A2 IT 2011000194 W IT2011000194 W IT 2011000194W WO 2011154984 A2 WO2011154984 A2 WO 2011154984A2
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WO
WIPO (PCT)
Prior art keywords
bullet
well
jacket tube
crushed
communicating
Prior art date
Application number
PCT/IT2011/000194
Other languages
French (fr)
Other versions
WO2011154984A3 (en
Inventor
Ignazio Congiu
Cristian Isopo
Original Assignee
Ignazio Congiu
Cristian Isopo
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to ITRM2010A000318 priority Critical
Priority to ITRM2010A000318A priority patent/IT1406544B1/en
Application filed by Ignazio Congiu, Cristian Isopo filed Critical Ignazio Congiu
Publication of WO2011154984A2 publication Critical patent/WO2011154984A2/en
Publication of WO2011154984A3 publication Critical patent/WO2011154984A3/en

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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/17Interconnecting two or more wells by fracturing or otherwise attacking the formation
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/25Methods for stimulating production
    • E21B43/26Methods for stimulating production by forming crevices or fractures
    • E21B43/263Methods for stimulating production by forming crevices or fractures using explosives
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24TGEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
    • F24T10/00Geothermal collectors
    • F24T10/20Geothermal collectors using underground water as working fluid; using working fluid injected directly into the ground, e.g. using injection wells and recovery wells
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24TGEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
    • F24T10/00Geothermal collectors
    • F24T2010/50Component parts, details or accessories
    • F24T2010/53Methods for installation
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/10Geothermal energy

Abstract

Process for creating an artificial permeable layer in subsurface for exploitation of geothermal energy, said process comprises the following steps: A) digging a well (2) by excavation means (1), and at the same time coating said well by a jacket tube (4), said jacket tube (4) comprising a plurality of elements that can be coupled in a removable way; B) removing excavation means (1); C) removing at least one element of said jacket tube (4) of the well (2) leaving a space between the lower end of said jacket tube (4) and the bottom of the well (2); D) inserting in said jacket tube (4) a bullet (P) containing at least one explosive charge (23); E) triggering said at least one explosive charge (23) of said bullet (P); F) firing said at least one explosive charge (23) of said one bullet (P), in the space between the lower end of said jacket tube (4) and the bottom of the well (2), with consequent creation of a crushed area (11) in the subsurface forming said artificial permeable layer. The invention further concerns a bullet for realizing said process.

Description

PROCESS FOR CREATING ARTIFICAL PERMEABLE LAYERS IN SUBSTRATE FOR EXPLOITATION OF GEOTHERMAL
ENERGY
The present invention concerns the field of renewable energy, such as geothermal energy, and refers to a process for realizing crushed zones or artificial permeable layers for exploitation of geothermal energy.
At present, exploitation of geothermal energy can be divided into two categories:
1. exploitation of average temperature (between 14°C and 18°C) from layers few meters under the surface, said temperature remaining almost the same during the year; and
2. exploitation of high temperature (higher than 100°C) from deeper layers.
In first case, relevant to exploitation of average temperatures, layers under earth surface are used as heat exchangers for heat pumps of conditioning systems.
Known conditioning systems heat or cool an environment, such as a house, following a request by the user based on the season of the year.
Said conditioning systems can take outer temperature or temperature of ground on which said home is provided, as reference temperature.
In the latter case, conditioning system must operate on a lower thermal difference than difference between house and outer air temperatures. The above causes a lower consumption of energy by said conditioning system.
In order to obtain energy sufficient for an average house (about 60 m2), it is necessary a not high investment, in case provision of a heat exchanger within the ground is made when realizing the building, e.g. on the bottom of the digging to realize groundwork, or investment can be high in case house has already been realized, and a suitable heat exchanger must be installed.
An- always higher number of companies provide solutions based on heat pump technology.
In second case, relevant to exploitation of high temperatures, it is possible exploiting heat for producing vapor and operating turbines that can produce electric power.
At present, for exploitation of geothermal energy, places having permeable layers in their subsurface are almost exclusively used.
Since costs for digging a well can be high, mainly due to the fact that some months are necessary to reach a set depth, it is necessary making first some searches. Said searches can be on the surface by suitable machines, to individuate at set depth presence of sufficient layers not comprised of compact rock, but of shingles or in any case a structure that is easily permeable to water.
This is due to the fact that a well digged only through compact rock involves disadvantage that rock thermal conductivity is not so high (e.g. granite has a conductivity of 3.5 Kcal/m h °C) and surface of well walls 2000 m2 even if well is depth (e.g. 5 km), from the above, it is understood, by simple known calculations, that energy that can be obtained from such a well is only sufficient to supply fifteen houses.
On the contrary, if one or more permeable layers are present at the bottom of the well, radiant surface can be considered much higher in correspondence of said layers.
If permeable layer has a sufficient extension, a plurality of wells can be realized so that water can be input within one or more of said wells and vapor can be extracted from wells different with respect to those within which water is input.
In fact, plants have been realized for exploitation of thermal energy and/or of vapor in correspondence of wells having a permeable layer on their bottom. However, geographical sites where it is possible digging to find a permeable layer are few.
At present, digging techniques are available, also for digging in compact rock, that are quicker and less expensive and that could make it convenient exploitation of sites having different rocky structure.
At present, sole technique to increase radiant surface is that of realizing a well by digging up to the wished depth, and filling it with water, on which a pressure is exerted by known means so that one or more fractures are created on the well bottom.
However, fractures realized by said technique cannot communicate each other. Thus, it is necessary digging further wells at an intermediate level with respect to the previous ones and creating further fractures communicating with the previous fractures.
Said technique has the disadvantage of requiring digging further wells, thus increasing costs.
A process for extracting geothermal energy is described in US patent 4,912,941.
However, said process has some drawbacks.
One of said drawbacks is that it is necessary providing a high number of steps for extracting thermal energy from subsurface, thus increasing time necessary for realizing the whole extraction process, thus increasing costs.
Particularly, said process for extraction of geothermal energy comprises the following steps:
- mechanically or by injecting acids, pulverizing crushed mass or making said crushed mass in a granular form,
- taking away said crushed mass so as to create a cavity at the bottom of said well,
- coating said cavity by a suitable heat conductive substance (cement based mortar with metallic inert) in order to increase thermal transmittance of cavity wall,
- inserting within cavity a first tube having a closed bottom and such a length to substantially arrive at the bottom of said cavity,
- inserting a suitable heat conductive composition to bring outer face of said first tube in thermal contact with rocky layer and with heat conductive substance,
- inserting a second tube, having an open bottom, within the first one, after that said first tube has been thermally coupled with surrounding rocky layer by said suitable composition, so as to create a closed going and return circuit for a vector fluid input within the annular space between the first tube and the second tube to bring heat up to the surface by said first tube.
Particularly, a drawback relevant to the step of coating cavity realized at the bottom of the well is due to the fact that suitable heat conductive substance closes fractures of crushed zone, thus remarkably reducing total radiant surface.
Furthermore, even if mortar used can have a higher thermal transmittance than the rock, it does not means that value of thermal transmittance of cavity rises up to reaching that of mortar, since rock thermal transmittance is not modified because physical properties of the rock are not modified.
Another drawback is that when reaching high depth, e.g. more than 2 km, it is difficult coating cavity realized by said mortar. This is due to the fact that possible mechanical means having the axis coincident with the well axis must spray mortar on fractures of said cavity, which are far away from said axis, and moreover mortar in correspondence of said fractures, once solidified, is subjected to collapsing caused by high temperature.
A further drawback is that insertion of a suitable vector fluid within the cavity makes the process complicated without substantially increasing amount of heat transported at surface with respect to the energy transported by a well having the same diameter and depth, without a cavity.
Still another drawback is that such a process necessarily provides a further perforation or drilling step of the same well to create further fractures, thus increasing time necessary for realizing such process, and increasing costs.
A projectile to be used for creating fracture within subsurface is described in DE patent n° 745 659.
Said projectile comprises an explosive charge and a timing fuse or an impact fuse, as well as a plurality of wings.
It is object of the present invention that of overcoming said drawbacks, providing a process for realizing an impermeable layer within subsurface by a lower number of steps with respect to known processes and reduced costs with the same geothermal energy extracted, wherein said permeable layer comprises a crushed zone or a plurality of crushed zones, communicating each other, by one or more fractures, so as to increase radiant surface for exploiting geothermal energy, wherein each crushed zone is an artificial permeable layer.
It is therefore specific object of the present invention is a process for creating an artificial permeable layer in subsurface for exploitation of geothermal energy, said process comprises the following steps:
A) digging a well by excavation means, and at the same time coating said well by a jacket tube, said jacket tube comprising a plurality of elements that can be coupled in a removable way;
B) removing excavation means;
C) removing at least one element of said jacket tube of the well leaving a space between the lower end of said jacket tube and the bottom of the well; D) inserting in said jacket tube at least a bullet containing at least one explosive charge;
E) triggering said at least one explosive charge of said bullet;
F) firing said at least one explosive charge of said one bullet, in the space between the lower end of said jacket tube and the bottom of the well, with consequent creation of a crushed area in the subsurface forming said artificial permeable layer.
According to the invention, steps D) to F) can be repeated at least once.
Always according to the invention, the step of inserting in the jacket tube of the bullet can be implemented leaving said bullet in free fall, or thrusting said bullet.
Still according to the invention, said bullet can comprise a plurality of explosive charges, said explosive charges can be fired at the same time or at different times.
According to another aspect of the invention, after step F), it is possible providing the following steps:
G) setting, according to the size of crushed area created in the subsurface at the stage F), the lateral distance at which create a further crushed area so that said further crushed area is communicating with the crushed area previously created;
H) repeating steps A) to F) to create a further crushed area at the distance determined to the step G), said further crushed area being communicating with the crushed area previously created.
According to the invention, said steps G) and H) can be repeated until when a desired number of crushed areas communicating with each other is obtained.
According to another aspect of the invention, after the creation of a further crushed area communicating with a crushed area previously created (step H)), each crushed area being provided near the bottom respectively of a first well and a second well, the following stages are provided:
l)connecting said first and second wells to a pump through a respective duct;
L)inserting in the jacket tube of said first well a bullet with a diameter about equal to that of said jacket tube;
M)sucking by said pump the air underlying the bullet coming from said second well, said air passing from said first well to said second well through one or more fractures that make the two crushed areas communicating, and inserting by said pump the sucked air above said bullet so that said bullet undergoes an increase in acceleration.
Still according to the invention, after the creation of a plurality of crushed areas communicating with each other, each crushed zone being provided near the bottom of a respective well, the following steps are provided:
l)connecting said wells to a pump through a respective duct; L)inserting in the jacket tube of a well a bullet with a diameter about equal to that of said jacket tube;
M)sucking by said pump the air underlying the bullet coming from the other wells, passing from the well in which said bullet is inserted to the other wells through one or more fractures that make the crushed areas communicating, and inserting by said pump the sucked air above said bullet so that said bullet undergoes an increase in acceleration.
Always according to the invention, between the step of removing an element of the jacket tube (step C)) and the step of insertion in said jacket tube of a bullet (step D)), or after the step of creating a crushed area (stage F)), a step for inserting into the jacket tube a target or impact element is provided, to allow bullet to explode at a point between the lower end of the jacket tube and the bottom of the well.
It is further object of the present invention a bullet that, in a first embodiment, can have an elongated shape and can comprises one or more explosive charges, an electronic control unit which controls the timing of the explosions of said explosive charges, and at least one detonator for said explosive charges connected to said electronic control unit.
Said bullet further comprises a rigid protection and an insulating layer, below said rigid protection; said insulating layer being a layer of glass foam or glass wool or rock wool or ceramic or other insulating material for high temperatures.
In said first embodiment, said bullet provides a plurality of radially arranged wings on its outer surface, each wing having a length that come into contact with the inner surface of a jacket tube of a well in which it is inserted.
Always according to the invention, said plurality of wings is arranged in groups, each of which is located at a different height on the outer surface of the bullet.
Still according to the invention, a detonator is provided for each explosive charge, each one connected with said electronic unit.
Furthermore, according to the invention, said bullet can further comprise a pin having a free end protruding from the bullet and the other end being in contact with the detonator of an explosive charge.
Always according to the invention, said bullet can comprise a propeller to lose, such as a compressed air propeller or a solid propellant.
It is further object of the present invention a bullet that, in a second embodiment, can have an elongated shape and comprises one or more explosive charges, an electronic control unit which controls the timing of the explosions of said explosive charges, and at least one detonator for said explosive charges connected to said electronic control unit.
Said bullet further comprising a rigid protection and an insulating layer, underlying said rigid protection; said insulating layer being a layer of glass foam or glass wool or rock wool or ceramic or other insulating material for high temperature.
In said second embodiment, said bullet has a diameter about equal to that of a jacket tube of the well in which it is inserted.
According to the invention, said bullet provides a detonator for each explosive charge.
Still according to the invention, said bullet comprises a pin having a free end protruding from the bullet and the other end being in contact with the detonator of an explosive charge.
Furthermore, according to the invention, said bullet can comprise a propeller to lose, such as a compressed air propeller or a solid propellant.
The present invention will be now described for illustrative, but not illustrative, purposes, according to an embodiment, with particular reference to the enclosed figures, wherein:
figure 1 schematically shows the digging step of a well by digging means providing jacketing the well by a jacket tube comprising a plurality of elements that can be removably coupled each other;
figure 2 schematically shows well digged until a set depth;
figure 3 schematically shows the well lined by jacket tube with digging means removed ;
figure 4 shows well digged of figure 3 with one element of the jacket tube removed so as to leave a space between lower end of said jacket tube and the bottom of the well;
figure 5 schematically shows introduction of a bullet within jacket tube;
figure 6 schematically shows explosion of the bullet on the bottom of the digged well;
figure 7 schematically shows a crushed zone created on the bottom of the well following the explosion of the bullet;
figure 8 shows, besides crushed zone of figure 7, two further crushed zones created by bullets explosion, each one inserted within a relevant well, where said crushed zones communicate each other;
figure 9 schematically shows operation of a system exploiting vapor extracted from a well different with respect to the one within which water has been introduced;
figure 10 shows a longitudinal section of a first embodiment of bullet of figure 5;
figure 11 is a cross section of bullet of figure 10 inserted within well jacket tube;
figures 12a and 12b schematically show a target or impact element, respectively in a rest position and a working position, to be inserted within tube jacket to be positioned within the well and to make the bullet exploding at a height different with respect to the bottom of the same well;
figure 13 shows a longitudinal section of a variation of the first embodiment of the bullet;
figure 14 is a cross section of a well within which a jacket tube is inserted to introduce water, having a diameter lower than the jacket tube diameter to permit exit of vapor from space between outer surface of said water input tube and inner surface of jacket tube;
figure 15 shows a longitudinal section of a second embodiment of the bullet;
figure 16 is a cross section of bullet of figure 15 inserted within the well jacket tube;
figure 17 shows two crushed zones, communicating each other, each of them being realized on the bottom of a relevant well following the explosion of a bullet of figure 10 inserted within each well, wherein said wells are connected each other so that air under the bullet of figure 15 inserted within a first well exits from second well to be pumped within the first well so as to generate an air pressure on said bullet;
figure 18 schematically shows realization of a rocky layer of a secondary branch until arriving close to its bottom.
Making reference to figures 1 - 7, it is provided a process for realizing artificial permeable layers for exploiting thermal energy, said process comprising the following steps:
A) digging a well 2 up to a set depth 6 with respect to the surface 3, by excavation means, and at the same time coating said well wall by a jacket tube 4, said jacket tube comprising a plurality of elements that can be coupled in a removable way;
B) removing excavation means 1 ;
C) removing at least one element of said jacket tube 4 of the well 2 leaving a space between the lower end of said jacket tube 4 and the bottom of the well 2;
D) inserting in said jacket tube 4 at least one bullet P containing at least one explosive charge 23;
E) triggering said at least one explosive charge 23 of said at least one bullet 23;
F)firing said at least one explosive charge 23 of said at least one bullet P, in the space between the lower end of said jacket tube 4 and the bottom of the well 2, with consequent creation of a crushed area 11 in the subsurface forming said artificial permeable layer.
As to the well digging step (step A), depth 6 of the well 2 with respect to surface 3 is chosen as a function of rocky layer temperature useful to exploitation of thermal energy and/or of the subsurface layer having a set mechanical resistance, e.g. a layer with a lower mechanical resistance, such as that created by limestone or sandstone rocks.
Still with reference to the well digging step (step A)), excavation means 1 comprise a drill. In the example described in the following, well 2 is digged in correspondence of an excavation system 5.
As to the step of insertion of bullet jacket tube 4 (step D), said bullet is let falling freely.
It is well evident that to introduce the bullet within the well 2 tube jacket 4, said bullet P must have a diameter lower than the jacket tube 4. The fact that bullet P diameter is lower than diameter of jacket tube 4 permits to air exiting upward, toward surface 3, thus preventing that the same is compressed.
In its first embodiment, bullet P provides a plurality of radial wings 22 of such a length to be in contact with inner surface of the jacket tube 4, so that bullet P is coaxial with respect to jacket tube 4 within which it is inserted.
Thus, bullet reaches the bottom of the well 2 in few seconds. Bullet P shown in figure 1 has three groups of wings 22, each group being provided at a different height on outer surface of the bullet P.
It is well evident that larger is the well 2 diameter, larger is the diameter of the jacket tube 4, and larger is the diameter of the bullet P. consequently, said bullet P can contain a bigger explosive charge, thus permitting obtaining a wider crushed area 11 , and thus a larger radiant surface to be used for exploiting geothermal energy.
As far as triggering step of said at least one explosive charge 23 of the bullet P is concerned (step E), said triggering is controlled by an electronic unit 33 provided within the bullet.
Electronic unit 33 controls explosions of explosive charges 23 according to a set timing.
To this end, a detonator, connected to the electronic unit 33, is provided for each explosive charge 23.
In the described example, bullet P has a lengthened shape and comprises two explosive charges, a first explosive charge 23 and a second explosive charge 23, each one actuated by a relevant detonator, a first impact detonator 29 for the first explosive charge 23 and a second detonator 29 for the second explosive charge 23 (figure 10).
Therefore, electronic unit 33 can control explosion of second charge 23 at a moment different from the time of explosion of first charge 23.
Particularly, bullet P can be divided into three parts: a head 30, a body 31 and a tail 32.
Bullet P head 30 provides a pin 28 having a free end exiting from said head 30 and a head contacting the first detonator 29, so that when free end of said pin 28 impacts against the well bottom 2, other end activate first detonator.
As already mentioned, even not shown in the figures, number of explosive charges within bullet P can be any one, even higher than two. For example, it is possible providing that bullet P has three charges: a first charge, a second charge and a third charge, between said first and second charge. In this case, if first charge and second charge explode at the same time, slightly before the third charge, thus generating a larger crushed zone at a set height. This can be useful when it is wished intervening on a rocky layer at a set depth different with respect to the depth 6 of the well 2.
Furthermore, bullet is provided with a stiff protection 24 realizing a jacket of the same bullet, and an insulating layer 21 , under said rigid protection (fig. 11).
Rigid protection 24, along with wings 22, ensures a rectilinear movement of bullet P while falling within the jacket tube 4, thus improving aerodynamic features and preventing explosion of explosive charge 23 due to sudden displacements and/or shocks against jacket tube 4.
Insulating layer 21 can be a layer of glass foam or glass wool or rock wool or ceramic or other insulating material for high temperatures, preventing that explosive charges 23 accidentally explode due to high temperatures that can be met at high depth.
In an embodiment shown in figure 13, projectile is provided with a loose propulsor 31 , e.g. a compressed air propulsor or a solid fuel propulsor. In this embodiment, a reservoir 35 is provided, connected with said propulsor 31.
Therefore, as far as step of insertion within jacket tube 4 of bullet (step D)), said bullet is pushed by said loss propulsor 31 , besides gravity effect.
According to the invention, after step F), it is possible providing the following steps:
G) setting, according to the size of crushed area 11 created in the subsurface at the stage F), the lateral distance at which create a further crushed area 11 so that said further crushed area 11 is communicating with the crushed area 11 previously created;
H) repeating steps A) to F) to create a further crushed area 11 at the distance determined to the step G), said further crushed area 11 being communicating with the crushed area 11 previously created.
Said steps G) and H) can be repeated until when a desired number of crushed areas 11 communicating with each other is obtained.
In the example described, three crushed zones 11 are realized, communicating each other.
One realized said crushed zones 11 , it is possible inputting water, or another fluid, into one or more of said wells 2, so that said water or other fluid exit vaporized and under pressure from wells different from those in which said water or other fluid has been introduced.
Thus, advantageously, it is possible using water or vaporized and under pressure fluid to obtain mechanical and/or electric and/or thermal energy.
A system is shown in figure 9 using vapor exiting from two wells provided aside the well within which water is input.
Said system comprises a condensation tower 15 and an apparatus 17 to transform thermal energy into electric energy provided to the users by an electric distribution line 18.
Even with a single well 2 it is possible using water or vaporized and under pressure fluid to obtain mechanical and/or electric and/or thermal energy.
To this end, it is sufficient introducing a tube 26 within said well 2 for introducing water so that water or vaporized and under pressure water or fluid to obtain mechanical and/or electric and/or thermal energy exiting from space between said tube 26 for introducing water and well 2 jacket tube 4 (figure 14).
In this specific case, both water input tube 26 and jacket tube 4 are coated by an insulating layer, respectively one layer 27 and one layer 47.
According to the invention, it is also possible providing that step A comprises a sub step between digging the well and jacketing the walls of the same relevant to creation of one or more secondary branches 2' of the well within the rocky layer. Each secondary branch 2' is realized by a plurality of branches in series, each one realized introducing a wedge within previous branch to deviate tip of a drilling machine, but the first branch created introducing a wedge within the digged well.
It is preferred that first wedge, i.e. wedge within the well, is provided within the same well in correspondence or slightly above the height provided for realizing the crushed zone (fig. 18).
Said secondary branches 2' can be used to transport water or other fluid at the bottom of the well by ducts to be introduced inside. Said ducts can be used to make air under a bullet P exiting. Advantageously, this permit introducing a bullet P within the well having the same diameter of the digged well. In the described example, it is shown only a secondary branch comprising three branches (fig. 18).
Furthermore, according to the invention between the step of removing an element of said jacket tube 4 (step C)) and step of insertion of the jacket tube 4 of a bullet (step D)), it is possible providing a step for inserting a target or impact element 12 to permit to the bullet P to explode in a point between the lower end of the jacket tube 4 and the well 2 bottom (figures 12a, 12b).
Particularly, said impact element 12 can be inserted within jacket tube 4 after explosion of the first bullet P so that second bullet P can explode in a different point with respect to the explosion of the first bullet P, since the crushed zone 11 , created after the explosion of the first bullet P, can have an impact surface not suitable for explosion of the second bullet P. in fact, space between lower end of the jacket tube 4 and the well 2 bottom can be obstructed by rocks crushed by explosion of the first bullet P. in this case, one or more elements of the jacket tube 4 are removed, thus leaving a space between the lower end of said jacket tube 4 and said crushed rocks, before second bullet P is inserted within the jacket tube 4.
In a second embodiment, it is provided a bullet P' without wings
22, and a diameter about equal to the jacket tube 4 within which is inserted (figures 15, 16).
Therefore, said bullet P', having a diameter almost equal to the diameter of the jacket tube 4, can contain an amount of explosive higher than that contained in the first embodiment of bullet and its embodiment, described in the above, and consequently permits realizing larger crushed zones 11.
The use of said bullet P' is limited to the case where crushed zones 11 , communicating each other, have already been created close to the bottom of the relevant wells 2 by explosion of a bullet P of the type described in the first embodiment or in the first embodiment.
In example shown in figure 17 two crushed zones 11 communicating each other, by one or more fractures, each one created on the bottom of a relevant well 2.
Two wells are connected at the surface by a relevant duct with a pump 36 so as to make air under the bullet P\ within a first well 2, passes to the second well 2 through one or more fractures, going to duct connecting said second well with said pump 36.
Pump 36 sucks said air, inputting the same within the first well 2, thus creating a pressure on the same bullet P'.
Thus, acceleration of bullet P', freely falling along first well 2, is increased without the needing of providing a propulsor within said bullet.
In other words, after creating a second crushed zone 11 , communicating with a first crushed zone (step H)), each crushed zone being provided close to the bottom of a first and a second well, the following steps are provided:
I) connecting said wells 2 to a pump 36 through a respective duct;
L) inserting in the jacket tube 4 of said first well 2 a bullet P' with a diameter about equal to that of said jacket tube 4;
M) sucking by said pump 36 the air underlying the bullet P' coming from the other wells 2, passing from the well in which said bullet is inserted to the other wells 2 through one or more fractures that make the crushed areas 11 communicating, and inserting by said pump 36 the sucked air above said bullet P' so that said bullet P' undergoes an increase in acceleration.
Advantageously, as already mentioned by the process according to the present invention, it is possible obtaining a radiant surface for exploiting geothermal energy by creation of a crushed zone or of a plurality of crushed zones communicating each other. A second advantage is due to the possibility of realizing by said process crushed zones and not fractures as in known solutions, thus increasing radiant surface for exploiting geothermal energy.
Present invention has been described for illustrative, but not limitative purposes according to its preferred embodiments, but it is understood that variations and/or modifications can be introduced by those skilled in the art without departing from the relevant scope as defined in the enclosed claims.

Claims

1. Process for creating an artificial permeable layer in subsurface for exploitation of geothermal energy, said process comprises the following steps:
A) digging a well (2) by excavation means (1), and at the same time coating said well by a jacket tube (4), said jacket tube (4) comprising a plurality of elements that can be coupled in a removable way;
B) removing excavation means (1);
C) removing at least one element of said jacket tube (4) of the well (2) leaving a space between the lower end of said jacket tube (4) and the bottom of the well (2);
D) inserting in said jacket tube (4) a bullet (P) containing at least one explosive charge (23);
E)triggering said at least one explosive charge (23) of said bullet (P);
F) firing said at least one explosive charge (23) of said one bullet (P), in the space between the lower end of said jacket tube (4) and the bottom of the well (2), with consequent creation of a crushed area (11) in the subsurface forming said artificial permeable layer.
2. Process according to claim 1 , characterized in that the previous steps D) to F) are repeated at least once.
3. Process according to any one of preceding claims, characterized in that the step of inserting in the jacket tube (4) of the bullet (P) (step D)) is implemented leaving said bullet (P) in free fall, or thrusting said bullet (P).
4. Process according to one of preceding claims, characterized in that said bullet (P) comprises a plurality of explosive charges (23), said explosive charges (23) can be fired at the same time or at different times.
5. Process according to any one of preceding claims, characterized in that after the step F), the following steps are provided:
G) setting, according to the size of crushed area (11) created in the subsurface at the stage F), the lateral distance at which create a further crushed area (11) so that said further crushed area (11) is communicating with the crushed area (11) previously created;
H) repeating steps A) to F) to create a further crushed area (11) at the distance determined to the step G), said further crushed area (11) being communicating with the crushed area (11) previously created;
said steps G) and H) can be repeated until when a desired number of crushed areas (11 ) communicating with each other is obtained.
6. Process according to claim 5, characterized in that after the creation of a further crushed area (11) communicating with a crushed area previously created (step H)), each crushed area (11) being provided near the bottom respectively of a first well (2) and a second well (2), the following stages are provided:
I) connecting said first and second wells (2) to a pump (36) through a respective duct;
L) inserting in the jacket tube (4) of said first well (2) a bullet (Ρ') with a diameter about equal to that of said jacket tube (4);
M) sucking by said pump (36) the air underlying the bullet (Ρ') coming from said second well (2), said air passing from said first well to said second well through one or more fractures that make the two crushed areas (11) communicating, and inserting by said pump (36) the sucked air above said bullet (Ρ') so that said bullet (Ρ') undergoes an increase in acceleration.
7. Process according to claim 6, characterized in that after the creation of a plurality of crushed areas (11) communicating with each other, each crushed zone (11) being provided near the bottom of a respective well (2), the following steps are provided:
l)connecting said wells (2) to a pump (36) through a respective duct;
L) inserting in the jacket tube (4) of a well (2) a bullet (Ρ') with a diameter about equal to that of said jacket tube (4);
M) sucking by said pump (36) the air underlying the bullet (Ρ') coming from the other wells (2), passing from the well in which said bullet is inserted to the other wells (2) through one or more fractures that make the crushed areas (11) communicating, and inserting by said pump (36) the sucked air above said bullet (Ρ') so that said bullet (Ρ') undergoes an increase in acceleration.
8. Process according to any one of preceding claims, characterized in that between the step of removing an element of the jacket tube (4) (step C)) and the step of insertion in said jacket tube (4) of a bullet (P) (step D)), or after the step of creating a crushed area (11) (stage F)), a step for inserting into the jacket tube (4) a target or impact element (12) is provided, to allow bullet (P) to explode at a point between the lower end of the jacket tube (4) and the bottom of the well (2).
9. Bullet (P) for carrying out the process according to any one of claims 1-8, characterized in that has an elongated shape and comprises one or more explosive charges (23), an electronic control unit (33) which controls the timing of the explosions of said explosive charges (23), and at least one detonator (29) for said explosive charges (23) connected to said electronic control unit (33); on the outer surface of said bullet (P) being provided a plurality of radially arranged wings (22), each wing having a length that come into contact with the inner surface of a jacket tube (4) of a well (2) in which it is inserted; said bullet (P) further comprising a rigid protection (24) and an insulating layer (21), below said rigid protection (24); said insulating layer (21) being a layer of glass foam or glass wool or rock wool or ceramic or other insulating material for high temperatures.
10. Bullet (P) according to claim 9, characterized in that said plurality of wings (22) is arranged in groups, each of which is located at a different height on the outer surface of the bullet (P).
11.· Bullet (P) according to any one of claims 9 or 10, characterized in that a detonator (29) is provided for each explosive charges (23).
12. Bullet (P) according to any one of claims 9-11 , characterized in that comprises a pin (28) having a free end protruding from the bullet (P) and the other end being in contact with the detonator (29) of an explosive charge (23).
13. Bullet (P) according to any one of claims 9-12, characterized in that comprises an propeller (31) to lose, such as an compressed air propeller or a solid propellant.
14. Bullet (Ρ') for carrying out the process according to any one of claims 6-8 (when depending from claims 6 or 7), characterized in that has an elongated shape and comprises one or more explosive charges (23), an electronic control unit (33) which controls the timing of the explosions of said explosive charges (23), and at least one detonator (29) for said explosive charges (23) connected to said electronic control unit (33); said bullet (Ρ') having a diameter about equal to that of a jacket tube (4) of a well (2) in which it is inserted; said bullet (Ρ') further comprising a rigid protection (24) and an insulating layer (21), underlying said rigid protection (24); said insulating layer (21) being a layer of glass foam or glass wool or rock wool or ceramic or other insulating material for high temperature.
15. Bullet (Ρ') according to claim 14, characterized in that a detonator (29) is provided for each explosive charges (23).
16. Bullet (Ρ') according to any one of claims 14-15, characterized in that comprises a pin (28) having a free end protruding from the bullet (Ρ') and the other end being in contact with the detonator (29) of an explosive charge (23).
17. Bullet (Ρ') according to any one of claims 14-16, characterized in that comprises a propeller (31) to lose, such as a compressed air propeller or a solid propellant.
PCT/IT2011/000194 2010-06-11 2011-06-10 Process for creating artifical permeable layers in substrate for exploitation of geothermal energy WO2011154984A2 (en)

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ITRM2010A000318A IT1406544B1 (en) 2010-06-11 2010-06-11 PROCEDURE FOR IMPLEMENTATION IN THE SUBSUBLE OF LAYERABLE ARTIFICIAL PERMEABLES FOR THE EXPLOITATION OF GEOTHERMAL ENERGY.

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NL2011040C2 (en) * 2013-06-26 2015-01-05 Source Geothermal B V Geothermal method.
WO2015116662A1 (en) * 2014-01-28 2015-08-06 Schlumberger Canada Limited Collapse initiated explosive pellet

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Publication number Priority date Publication date Assignee Title
CN103334734A (en) * 2013-06-09 2013-10-02 中国石油天然气股份有限公司 Transformation method of interlayer in SAGD (Steam Assisted Gravity Drainage) well
NL2011040C2 (en) * 2013-06-26 2015-01-05 Source Geothermal B V Geothermal method.
WO2015116662A1 (en) * 2014-01-28 2015-08-06 Schlumberger Canada Limited Collapse initiated explosive pellet
US10196894B2 (en) 2014-01-28 2019-02-05 Schlumberger Technology Corporation Collapse initiated explosive pellet

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IT1406544B1 (en) 2014-02-28
ITRM20100318A1 (en) 2011-12-12

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