U.S. patent application number 15/310042 was filed with the patent office on 2017-05-18 for method for introducing a borehole.
This patent application is currently assigned to THYSSENKRUPP AG. The applicant listed for this patent is THYSSENKRUPP AG. Invention is credited to Sergey Gorchakov, Johannes Kocher, Markus Oles, Arno Romanowski, Joachim Stumpfe, Dirk Uhrlandt.
Application Number | 20170138129 15/310042 |
Document ID | / |
Family ID | 53189017 |
Filed Date | 2017-05-18 |
United States Patent
Application |
20170138129 |
Kind Code |
A1 |
Oles; Markus ; et
al. |
May 18, 2017 |
METHOD FOR INTRODUCING A BOREHOLE
Abstract
Methods for constructing a borehole, in some examples, in the
Earth's crust, may involve holding a drill head in the borehole by
a linkage. The drill head may include a thermal device that causes
material on a base of the borehole to be released from the solid
phase via phase change. The released material may be removed in a
direction of the Earth's surface. Further, the thermal device may
be operated so that it generates a thermal output power high enough
to predominantly sublimate material when transitioning out of the
solid phase.
Inventors: |
Oles; Markus; (Hattingen,
DE) ; Stumpfe; Joachim; (Dusseldorf, DE) ;
Kocher; Johannes; (Kunzell, DE) ; Romanowski;
Arno; (Antrifttal, DE) ; Uhrlandt; Dirk;
(Wackerow, DE) ; Gorchakov; Sergey; (Greifswald,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THYSSENKRUPP AG |
Essen |
|
DE |
|
|
Assignee: |
THYSSENKRUPP AG
Essen
KR
|
Family ID: |
53189017 |
Appl. No.: |
15/310042 |
Filed: |
May 4, 2015 |
PCT Filed: |
May 4, 2015 |
PCT NO: |
PCT/EP2015/059707 |
371 Date: |
November 9, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 47/07 20200501;
E21B 7/15 20130101; E21B 7/14 20130101 |
International
Class: |
E21B 7/15 20060101
E21B007/15; E21B 47/06 20060101 E21B047/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2014 |
DE |
10 2014 106 843.2 |
Claims
1-11. (canceled)
12. A method for introducing a borehole into Earth's crust, the
method comprising: holding a drill head in the borehole by a
linkage; operating a thermal device of the drill head so that the
thermal device generates a thermal output power high enough to
cause material on a base of the borehole to be released from a
solid phase via phase change predominantly by way of sublimation;
and removing the released material in a direction of an opening of
the borehole.
13. The method of claim 12 wherein at least 40% by weight of the
material released from the solid phase via sublimation transitions
into a gaseous phase.
14. The method of claim 12 wherein at least 90% by weight of the
material released from the solid phase via sublimation transitions
into a gaseous phase.
15. The method of claim 12 wherein at least 95% by weight of the
material released from the solid phase via sublimation transitions
into a gaseous phase.
16. The method of claim 12 further comprising monitoring a phase
state of the released material at the base of the borehole with a
sensor attached to the drill head.
17. The method of claim 12 further comprising regulating a quantity
of liquefied material on the base of the borehole to a specified
nominal value by controlling the thermal output power, wherein the
thermal output power is increased for a reduction in the quantity
of liquefied material.
18. The method of claim 12 comprising operating the thermal device
at a heating power of at least 80 kW.
19. The method of claim 12 comprising operating the thermal device
at a heating power of at least 1,000 kW.
20. The method of claim 12 comprising operating the thermal device
so as to generate a temperature of at least 2,000 K.
21. The method of claim 12 comprising operating the thermal device
so as to generate a temperature of at least 5,000 K.
22. The method of claim 12 further comprising cooling at least the
released material that has been sublimed by a cooling gas stream
separate from a plasma jet.
23. The method of claim 22 wherein the cooling gas stream forms a
gas cushion between the released material that has been sublimed
and the drill head.
24. The method of claim 23 further comprising blowing the cooling
gas stream into a gap between the drill head and the borehole.
25. A device for introducing a borehole into Earth's crust, the
device comprising: a drill head; a linkage for holding the drill
head in the borehole; a thermal device disposed on the drill head
that causes material on a base of the borehole to be released from
a solid phase via phase change; and a sensor for monitoring a phase
state of the released material at the base of the borehole.
26. The device of claim 25 wherein the sensor is attached to the
drill head.
27. The device of claim 25 wherein the sensor is a photo-optical
sensor.
28. The device of claim 25 wherein the sensor is a pyrometer.
29. The device of claim 25 wherein the thermal device causes the
material on the base of the borehole to be released from the solid
phase via phase change predominantly by way of sublimation.
Description
[0001] The invention relates to a method for introducing a
borehole, particularly into the Earth's crust.
[0002] Mechanical drilling methods are conventionally used today in
order to exploit oil and natural gas sources. Said mechanical
drilling methods apply a rotating bit in order to remove the rock
from the borehole. In addition to the rotating method, there are
also percussive or rotary-percussive drill bits. The drill bit is
driven mechanically or hydrodynamically. Linkages, which are
commonly screwed together or inserted in sections, transmit
mechanical energy to the bit to remove rock material. Cooling is
required for this process. Cooling is performed by a drilling fluid
that consists, to a great extent, of water. In addition to cooling,
the fluid is also used to transport the removed drill cuttings from
the base of the borehole upward. However, said cooling and removal
methods are limited by the high temperatures which prevail at
depths, particularly at greater than 2,000 m. The temperatures here
are high enough that the drilling fluid can no longer perform
effective cooling. This is one of the reasons why drilling at
depths of greater than 2,000 m is difficult to perform. Above a
certain temperature, the cooling fluid begins to boil and thus can
no longer discharge sufficient heat or rock. The depths that can be
reached are also limited by the respective geological conditions of
the rock in the respective borehole. The boiling point of the
drilling fluid can be increased by various additives, which enables
its functionality even at high temperatures; however, there are
technical limits to these adjustment possibilities.
[0003] WO 2013/135391 A2 discloses a method for introducing
cavities into rock, wherein the rock on the front of the cavity is
thermally melted. The liquefied rock is removed from the cavity
using a gaseous medium. The heat required in order to melt the rock
is provided by a plasma generator arranged on a tunneling head. The
high temperatures in the borehole create no significant
disadvantages for this method.
[0004] Handling of the liquefied rock is problematic with plasma
drilling, however, as it must be conveyed past the drill head to
the opening of the borehole. The liquefied rock can precipitate
(condense) on the drill head. This can lead to destruction of the
drill head, which creates high costs and downtime. Until now, this
problem has been approached by keeping the fluid level at the base
of the borehole as low as possible. The power of the plasma
generator is reduced for this purpose. This naturally slows the
drilling progress, since the feed rate is extensively linear in
relation to the thermal output power. In this respect, plasma
drilling is currently rarely applied cost-effectively.
[0005] The invention aims to solve the problem of providing an
improved method for constructing boreholes, which is particularly
characterized by fast advancing and by high endurance.
[0006] Said problem is solved by a method for constructing
boreholes, particularly into the Earth's crust, by means of a drill
head which is held in the borehole on linkages, wherein the drill
head comprises a thermal device which causes material, particularly
rock, on the base of the borehole to be released from the solid
phase via phase change, wherein the released material is taken away
in the direction of the opening of the borehole, particularly to
the Earth's surface. According to the invention, the thermal device
is operated so that it generates a high thermal output power, by
means of which the material predominantly sublimates when
transitioning out of the solid phase.
[0007] The core of the invention lies particularly in the fact
that, due to sublimation in a thermal drilling method, the material
does not transition into the liquid phase at all. In fact, said
phase is skipped over by sublimation. The risk of precipitation of
liquid material on the drill head is immensely reduced as a result.
The risk of liquid rock splashing onto the drill head and
precipitating there is also reduced. In contrast to the plasma
drilling according to the prior art described above, the power
input is consequently not reduced according to the invention, but
rather instead increased in order to prevent the formation of
liquid material. Increasing the thermal power on the material
reduces the melting depth to less than 1 cm, which leads to a
significant reduction in the proportion of liquid material on the
base of the borehole; this is due to the short-term cooling effect
of the sublimation on the subjacent material layers. By increasing
the thermal output power, the possible feed rate simultaneously
increases.
[0008] Furthermore, sublimation of the material enables fast
removal of the material. Immediately after the torch or, in
individual cases, controlled by cooling nozzles, the material
resublimates into small particles which can be easily flushed out.
Unlike methods that transition through a liquid phase, the
particles created during resublimation are significantly smaller
than the particles created by condensation.
[0009] So-called plasma torches are particularly used as the
thermal device, whereby the expression "torch" is sometimes used
incorrectly in this context. The present method depends on the high
temperatures that the device generates; however, this does not
necessarily have to be accompanied by burning, or oxidation.
Optical devices, such as lasers, are also generally conceivable, if
they can provide the required thermal power.
[0010] At least 50 wgt.-%, preferably at least 80 wgt.-%, at least
90 wgt.-% or at least 95 wgt.-% of the material released from the
solid phase via sublimation transitions into the gaseous phase. The
rest of the released material first melts and only then transitions
to the gaseous phase, if at all. The high proportion of sublimated
material also causes an abrupt volume enlargement which removes any
liquid components from the solid surface on the base of the
borehole. In this respect, it is not necessarily required that the
material be released from the solid phase only by sublimation.
[0011] In conventional surface treatment of rock pieces by means of
a plasma jet, rock is also sporadically sublimated, as described in
DE 19 43 058 C3, for example; a thermal drilling tool being
intentionally brought to a power level that sublimates instead of
melting the majority of the rock in order to solve the stated
problem has not previously been described, however.
[0012] Feed rates of 2-10 mm/s can be achieved according to the
invention. Under optimal operating conditions, plasma drilling also
has potential for longer service life compared to mechanical
drilling methods.
[0013] The phase state of the material to be released, particularly
at the base of the borehole, is preferably monitored by at least
one sensor attached on the drill head. The proportion of liquid
material in the total output can thus be determined and measured
initiated as required. To this end, the phase state of the drilling
material on the base of the borehole is optically monitored by
means of the sensor attached on the drill head. The proportion of
the liquid phase in the total output can thus be continually
determined. The sensor is particularly based on pyrometric
temperature measurement and serves to determine the temperature
difference between the released material on the base of the
borehole and the side wall of the borehole. The method according to
the invention utilizes temperature differences between the solid
and liquid phase. The proportion of the liquid phase can be
determined from the specification of the meniscus, using a
mathematical method in connection with the flash pressure of the
liquid phase.
[0014] A quantity of liquefied material on the base of the borehole
is preferably regulated to a specified nominal value by regulating
the thermal output power, wherein the thermal output power is
increased for a reduction in the quantity of liquefied material.
Such a regulation can ensure that the liquid proportion of released
material does not become too great. By reducing the liquid
proportion, the risk of clogging the borehole is kept low, without
also reducing the feed rate.
[0015] There are special conditions in deep boreholes of more than
1000 m in depth. The rock there particularly has one or more of the
following parameters:
[0016] Density: 1300-4000 kg/m3; [0017] Thermal conductivity: 2-5
W/m K; [0018] Specific thermal capacity: 600-2000J/kg K; [0019]
Melting point: 600-2000.degree. C.; [0020] Boiling temperature:
2800-4000 K [0021] Evaporation enthalpy: 2 MJ/kg;
[0022] The borehole particularly exhibits the following
parameters:
[0023] Distance from surface of the Earth to the base of the
borehole (depth of borehole): at least 1,000 m, particularly at
least 2,000 m or at least 4,000 m.
[0024] Diameter of the borehole 2-30 cm, particularly less than 20
cm.
[0025] The method described here is particularly suitable for
producing boreholes with a high aspect ratio (ratio of the depth to
the diameter of the borehole) of at least 1,000:1 particularly of
at least 3,000:1 or at least 10,000:1, or, in the case of very deep
boreholes, at least 20,000:1 or at least 100,000:1.
[0026] The power of the thermal device--that is, the thermal output
power occurring in the method--is at least 80 kW, preferably at
least 1,000 kW.
[0027] If a plasma generator device is chosen as the thermal
device, the temperature of the emitted plasma beam on the drill
head should equal 2,000 K, preferably at least 5,000 K, in order to
cause sublimation to the required extent. The following gases can
be used: nitrogen, acetone, oxygen, hydrogen, helium, argon and
carbon dioxide. The power density equals preferably at least
10.sup.7 W/m.sup.2, preferably 5.times.10.sup.7 W/m.sup.2. Power
density is considered to be the thermal power per unit of area
which is applied by the thermal device to the surface of the
rock.
[0028] A gas stream is preferably used for this in order to convey
the removed material toward the surface, particularly the surface
of the Earth. This can be the same gas that is also used for a
plasma jet. The material is then guided past the side of the drill
head, particularly through a gap between the drill head and the
borehole.
[0029] The sublimated material is preferably cooled by a cooling
gas stream separate from the plasma jet. This preferably forms a
gas cushion between the sublimated rock and the drill head. In
particular, said cooling gas stream or gas cushion first of all
ensures that the sublimated material does not come into contact
with the drill head. Second of all, a cooling of the sublimated
material can be effected so that resublimation and, as a result, a
sort of dust collection or formation of the smallest of particles
occurs. Said dust material is then conveyed upward through the gap.
The resublimation can also occur directly on the wall of the
borehole, so that the material deposits there and effects a
vitrification of the borehole.
[0030] The cooling gas stream is preferably blown laterally into
the gap between the drill head and the borehole. The gaseous
material is thus prevented from coming into contact with the drill
head and condensing and solidifying or resublimating thereupon.
[0031] The invention furthermore relates to a device for
constructing a borehole, particularly into the Earth's crust. The
device comprises a drill head, a linkage for holding the drill head
in the borehole, and a thermal device arranged on the drill head,
which causes the material on the base of the borehole to be
released from the solid phase via phase change. According to the
invention, the device furthermore comprises a sensor, particularly
attached to the drill head, by means of which the phase state of
the loosened material can be monitored, particularly on the base of
the borehole. A photooptical sensor, particularly a pyrometer, can
be used as a sensor. The regulating of the thermal output power
described above can be implemented by means of such a device.
[0032] The invention is described below in greater detail based on
the figures. Here,
[0033] FIG. 1 shows a borehole having a drill head introduced
therein, in cross-section;
[0034] FIG. 2 shows a schematic of the borehole according to FIG.
1, having different characteristics of the liquid level on the base
of the borehole.
[0035] FIG. 1 shows a borehole 1 which is introduced into the
Earth's crust 3 from the surface of the Earth 7. The depth T of the
borehole (=distance from the Earth's surface 7 to the base 2 of the
borehole 1) equals approximately 4,000 m. The borehole is to be
enlarged so that further depths can be penetrated. A drill head 4
is provided for said purpose which is held by a linkage 5, which
extends coaxially to the borehole 7 from the Earth's surface 7 into
the borehole 7. A plasma generator device 6, which generates a
plasma jet 8, is arranged inside the drill head 4. By means of the
plasma jet 8, which has a temperature of 2,000 K or more, rock 3 on
the base 2 of the borehole 1 is released from the solid phase and
thus cleared away.
[0036] The basic structure of the plasma generator device
corresponds to already known devices of this type and comprises a
central, internal anode 10 and an annular cathode 9, arranged
coaxially to the anode 10. A gas suitable for forming plasma, such
as nitrogen, oxygen, hydrogen, argon, helium or carbon dioxide, is
blown at high pressure via a supply line 1 into the region between
the cathode 9 and the anode 10. With correspondingly applied high
voltage, the arrangement of the anode 10 and cathode 9 generates an
electrical arc, by means of which the plasma or the plasma jet 8 is
produced. As a result, the gas undergoes a temperature increase to
more than 2,500 K, which is necessary for removal of the rock.
[0037] Therefore, the plasma jet 8 is brought to a power level that
predominantly sublimates the rock and does not melt it first.
Liquid rock is thus extensively prevented from collecting on the
base 2 of the borehole 1. Liquid rock is to be avoided, since it
easily sets on the drill head and can damage the drill head as a
result. Furthermore, it can collect in the annular gap between the
drill head and borehole, causing an obstruction there.
[0038] It must be ensured that the released gaseous rock returns to
the solid phase as quickly as possible, and sublimates and
solidifies as finely grained as possible. A shell channel 12 is
formed for this purpose within the drill head 4, which is arranged
in an annular manner around the plasma generator device 6. A
cooling gas stream 15 flows through said shell channel 12, likewise
originating from the supply line 11, at high speed. Said gas exits
from the shell channel 12 near a face 17--that is, the downward
pointing region of the drill head--and ensures that a sort of gas
cushion 16 is formed between the plasma gas 13, together with the
sublimated rock, and the drill head 4. Said gas cushion 16 is
required where the rock is present in gaseous form, which is marked
by the line drawn and identified with reference sign 13. Moreover,
due to said gas cushion 16, prompt cooling of the gaseous rock
occurs, causing it to resublimate and to thus take a solid,
dust-like form. This is shown in the figure by the dotted line
identified by reference sign 14. Mixing with the cooling gas stream
15 and common discharge of cooling gas stream 15 and plasma gas
stream 14 together with resublimated rock then occurs in the
direction of the Earth's surface 7.
[0039] The determination of the liquid level on the base of the
borehole 2 is explained based on FIG. 2. A pyrometer 17 measures
the temperature distribution on the borehole 1 in the region of the
drill head 4. Solid components, such as the edge of the borehole 1,
have a lower temperature than liquid components, namely the
liquefied rock 18; liquid components have a lower temperature than
gaseous components. The shape of the meniscus, or the curvature of
the liquid surface on the base 2 of the borehole 1, can be
determined on this basis.
[0040] The shape of the meniscus is linked to the liquid level on
the base of the borehole. FIG. 2a shows a meniscus having a steep
outer region, which indicates a low liquid level. FIG. 2b shows a
meniscus having a flat outer region, which indicates a higher
liquid level. A correlation between the shape of the meniscus and
the liquid level is created via mathematical models.
REFERENCE SIGN LIST
[0041] 1 Borehole [0042] 2 Base of the borehole [0043] 3
Rock/Earth's crust [0044] 4 Drill head [0045] 5 Linkage [0046] 6
Plasma generator device [0047] 7 Earth's surface [0048] 8 Plasma
jet [0049] 9 Cathode [0050] 10 Anode [0051] 11 Supply line [0052]
12 Shell channel [0053] 13 Plasma gas stream with sublimated rock
[0054] 14 Plasma gas stream with resublimated rock [0055] 15
Cooling gas stream [0056] 16 Gas cushion [0057] 17 Pyrometer [0058]
18 Liquid layer T Bore hole depth
* * * * *