Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02833178 2013-10-15
Description
Method for extracting hydrocarbon compounds, especially crude oil, from
underground oil sands deposits
[0001]The invention relates to a method for extracting hydrocarbon compounds,
especially crude oil, from underground oil sand deposits.
[0002]Processes known as ISC (in situ-combustion) processes are known for the
subterranean separation of low-fluidity bitumen from oil sand. In this
process, the
bitumen present in the oil sand is partly combusted and, for this purpose, air
is
injected into the porous oil sand, via a bore introduced into the oil sand
deposit, in
order to enable such combustion. The high-viscosity bitumen made fluid by the
combustion is then pumped off via drainage pipes. In such processes, a
firefront is
produced within the oil sand deposit, and moves through the deposit.
Controlling the
firefront presents problems.
[0003]Alternative processes are based on the introduction of hot steam into
the oil
deposit, in order to make the high-viscosity bitumen fluid and allow it to be
pumped
off.
[0004]The aim of the invention is to improve a method for extracting
hydrocarbon
compounds, especially crude oil, from underground oil sand deposits.
[0005]According to the invention, a method is provided, for this purpose, for
extracting hydrocarbon compounds, especially crude oil, from underground oil
sand
deposits, with the steps of introducing at least two bore sections parallel to
one
another into the oil sand deposit, of at least sectionally filling the bore
sections with
an explosive material, of detonating the explosive material to enlarge the
bore
sections, of igniting combustible material in at least one of the bore
sections, to
convert the hydrocarbon compounds present in the oil sand deposit into a
liquid
and/or gaseous state, and of collecting the hydrocarbon compounds present in a
liquid and/or gaseous state.
[0006]The method of the invention permits improved in situ bitumen extraction
and
also improved upgrading of the hydrocarbon compounds with a higher and more
rapid yield than in the case of the prior art described. By creating an
underground
cave system or cavern system through the introduction and enlargement of bore
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sections, the hydrocarbon compounds can be collected more easily and
completely.
Moreover, it is possible, for example, to blow in air, steam, or the like with
substantially greater control and simplicity, since enlarged bore sections are
available. In accordance with the invention, bores are sunk in the oil sand by
means
of a suitable drilling apparatus. After the bores have been introduced into
the oil
sand, bore sections lying within the oil sand are filled, at least
sectionally, with an
explosive material, and this explosive material is detonated. As a result, a
stable,
approximately cylindrical cavern is formed in the oil sand. At least two such
caverns
are produced parallel to one another. Then, in at least one of the caverns,
combustible material or ignitable mixture is provided, for example, by the
pumped
introduction of additional air, and this material or mixture is then ignited
by means, for
example, of pyrotechnic detonating charges. The combustion is then maintained.
Hot
combustion gases then penetrate the porous oil sand and liquefy the bitumen in
the
sand. The combustion then progresses also preferably in the radial direction
into the
surrounding oil sand. In the cavern itself, liquid and/or gaseous bitumen
and/or other
hydrocarbon compounds then collect, and can then simply be pumped off. Through
targeted, blown introduction of air and water/steam or other substances,
temperature
conversions and physical conversions within the caverns can be influenced.
When
the bitumen source is exhausted, i.e., the combustion zones and/or the
liquefaction
zones, which advance in the radial direction from the two caverns, come
together, the
supply of air is shut off. Optionally, CO2 may be pumped in to halt the
combustion
reliably. The bore sections can be enlarged underground without problems, by
detonation of the explosive material, and this enlargement represents the
precondition for a decisive improvement in the method of the invention, as has
already been the case in particular with regard to the more rapid, more
complete, and
more secure collecting of liquid or gaseous hydrocarbon compounds, and also in
respect of the more controlled propagation of a flame front in the oil sand.
[0007] In development of the invention, there is compacting of the oil sand
material
surrounding the outer surface of the bore sections, by means of the enlarging
of the
bore sections after detonating of the explosive material.
[0008]Compacting the oil sand material produces stable caverns which can be
utilized for the passage of gaseous and liquid hydrocarbon compounds and also
of
additives, and also for the combustion of combustible material. Especially in
the case
of porous and plastically deformable oil sand, such compaction may take place
very
easily by detonation of explosive material in a bore section.
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[0009] In development of the invention, air is supplied to the bore sections
to promote
the combustion of the combustible material, and off-gases formed during
combustion
are drawn off under suction.
[0010] In this way it is possible to maintain controlled combustion with
predetermined
parameters in the enlarged bore sections. Since the enlarged bore sections
form
caverns, such control or regulation of combustion can take place reliably,
since
physical exchange is possible comparatively rapidly in the volume of the
caverns, in
any case significantly more rapidly than would be the case for the blown
introduction
of air or gases in porous oil sand.
[0011]In development of the invention, water, steam, oxygen, carbon monoxide
and/or carbon dioxide is supplied to or targetedly withdrawn from the bore
sections in
order to influence temperature and physical conversions in the region of the
bore
sections; in this case, carbon monoxide and/or carbon dioxide may also come
from
the combustion itself.
[0012] In this way it is possible to design an underground refinery with
controllable
combustion parameters, physical conversion (upgrading) parameters, mass
transport
parameters, and heat transport parameters in the caverns formed by enlargement
of
the bore sections. For example, with the aid of gravity and of the flow regime
of
gases, more particularly air, combustion gases, pyrolysis vapors or smolder
vapors,
hydrocarbon vapors, etc., and liquids (hot bitumen and crude oil) can be
specifically
influenced. Temperature zones can be influenced in just the same advantageous
way. In addition, as in the case of above-ground upgrading processes, specific
physical conversions can be achieved and therefore partially cracked bitumen
also
upgraded by hydrogen hydrotreating (synthetic crude oil) can be synthesized
underground. This is accomplished, for example, by occasional (intermittent)
or
continuous injection of water or steam into a cavern filled with combustion
gases and
bitumen vapors. In a manner similar to steamcracking or thermal cracking, long-
chain
hydrocarbon molecules are split, and subsequently, using synthesis gas (CO and
H2
from steam and pyrolysis coke), unsaturated, short-chain hydrocarbon molecules
are
saturated with resultant hydrogen, also called hydrotreating. In order to
control
combustion or to extinguish the combustion zone, after the end of exploitation
of the
deposit, using CO2 introduced by pumping, carbon dioxide, for example, can be
pumped in. In this way it is also possible to a certain extent to store CO2.
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[0013]In development of the invention, the hydrocarbon compounds present in
the oil
sand deposit are split by means of the combustion into hydrocarbon chains of
different lengths and different aggregate states, with short-chain, lighter
and/or
gaseous chain components rising upward, and long-chain, heavier and/or liquid
chain
components falling downward. In specific secondary reactions, hydrogen is
formed
from water, in order to upgrade the hydrocarbons by hydrotreating.
[0014] In this way, by means of the geometry of the enlarged bore sections and
the
skillful arrangement of a plurality of enlarged bore sections, physical
partition within
the caverns can be influenced.
[0015] In development of the invention, the combustion of the combustible
material is
extinguished by the pumped introduction of an extinguishant, more particularly
by
means of an extinguishing gas, CO2 for example.
[0016]Combustion within the oil sand deposit or else only within the enlarged
bore
sections can be fully or partly extinguished in this way, in order to be able
to control
combustion rate and temperature, for example.
[0017]In development of the invention, provision is made for introducing a
first,
substantially vertical bore section down into the oil sand deposit, for
introducing a
second, substantially horizontal bore section into the oil sand deposit,
starting from
the first, vertical bore section, for introducing at least one third,
substantially
horizontal bore section into the oil sand deposit, starting from the first,
vertical bore
section or starting from a fourth, vertical bore section, the third,
horizontal bore
section being arranged with a vertical and/or horizontal offset from the
second,
horizontal bore section and running substantially parallel thereto, for at
least sectional
filling of the second, horizontal bore section and of the third, horizontal
bore section
with an explosive material, and for detonation of this explosive material, to
enlarge
the second, horizontal and third, horizontal bore sections, for ignition of
combustible
material in the second and/or third, horizontal bore section(s), to convert
the
hydrocarbon compounds present in the oil sand deposit into a liquid and/or
gaseous
state, and for collection of the liquid and/or gaseous hydrocarbon compounds.
[0018] In this way a particularly advantageous arrangement of the individual
enlarged
bore sections with respect to one another is achieved.
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[0019] In development of the invention, two or more second, horizontal bore
sections
and two or more third, horizontal bore sections are arranged in planes which
each
run parallel to one another.
[0020] In this way, a matrix of enlarged bore sections can be formed within
the oil
sand deposit, this being extremely advantageous for controlled propagation of
a
flame front in the oil sand deposit and also for the creation of defined sinks
or
collecting basins for liquid and/or gaseous hydrocarbon compounds. The oil
sand
deposits can be exploited more completely and also more environmentally as a
result, since, for example, combustion processes can be extinguished
completely by
blown introduction of CO2.
[0021] In development of the invention, two or more second, horizontal bore
sections
and two or more third, horizontal bore sections are arranged in a plane at a
predetermined distance from one another.
[0022] In development of the invention, provision is made for introducing at
least one
first, substantially vertical bore section down into the oil sand deposit, for
introducing
at least one fourth, substantially vertical bore section down into the oil
sand deposit,
substantially parallel to the first, vertical bore section, for at least
sectional filling of
the first and/or fourth vertical bore section(s) with an explosive material,
and for
detonating this explosive material, to enlarge the first and/or fourth
vertical bore
section(s), for igniting combustible material in the first and/or fourth
vertical bore
section(s), to convert the hydrocarbon compounds present in the oil sand
deposit into
a liquid and/or gaseous state, and for collecting the liquid and/or gaseous
hydro-
carbon compounds.
[0023] In this way, enlarged bore sections or caverns arranged vertically can
be
provided. Then, as in the case of rectifying columns, gases, vapors, and
liquids can
be fed in and tapped off at different heights. In this way as well it is
possible to design
an underground refinery.
[0024] In development of the invention, the first and fourth vertical bore
sections are
connected by means of horizontal bore sections, with at least one horizontal
bore
section connecting the vertical bore sections in an upper region, and at least
one
horizontal bore section connecting the vertical bore sections in a lower
region.
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[0025] In this way it is possible to enable a targeted flow regime in the
underground
caverns.
[0026] In development of the invention, at least one bore section is sealed
off from
the atmosphere. For example, connections between the underground caverns and
the atmosphere are sealed off provisionally, at least partly, by means of an
expandable or inflatable plug. An expandable plug casing is first expanded,
for
example, with air and/or with a fluid, resulting in an impervious seal in the
borehole.
Alternatively or additionally to air, for example, water, bentonite slurry, or
flowable
concrete can also be used for filling. This plug can thereafter be backfilled,
for
example with sand, gravel, bentonite slurry and/or concrete. In this way a
cavern can
be sealed off from the atmosphere or else from other caverns, in order to
create an
underground system of caverns and connections that can be utilized as an
underground refinery.
[0027] Further features and advantages of the invention will become apparent
from
the claims and from the following description of preferred embodiments of the
invention, in connection with the drawings. Individual features of the
different
embodiments shown may be combined arbitrarily with one another, without
exceeding the scope of the invention. In the drawings:
fig. 1 shows a schematic representation of a first step in the method of the
invention,
fig. 2 shows a schematic representation of a further step in the method of the
invention,
fig. 3 shows a schematic representation of a further step in the method of the
invention,
fig. 4 shows a schematic representation of a further step in the method of the
invention,
fig. 5 shows an arrangement of underground bore sections in accordance with
the
method of the invention in a second embodiment,
fig. 6 shows the arrangement of underground bore sections in accordance with
the
method of the invention in a third embodiment,
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fig. 7 shows the arrangement of underground bore sections in accordance with
the
method of the invention in a fourth embodiment,
fig. 8 shows the arrangement of underground bore sections in accordance with
the
method of the invention in a fifth embodiment,
fig. 9 shows a schematic representation of a further step in the method of the
invention,
fig. 10 shows an arrangement of underground bore sections in accordance with
the
method of the invention in a sixth embodiment, and
fig. 11 shows an arrangement of underground bore sections in accordance with
the
method of the invention in a seventh embodiment.
[0028]The representation in fig. 1 shows, schematically, a section through the
uppermost region of the Earth's crust. Arranged beneath a surface 10 of the
Earth is,
first of all, an intermediate layer 12, followed then by an oil sand deposit
14. The oil
sand deposit 14 is situated, for example, at a depth of more than 75 m,
corresponding to the thickness of the layer 12, and so the exploitation of the
oil sand
deposit 14 by open-cast mining is no longer rational. The oil sand deposit 14
must
therefore be exploited using what is called an in situ method. In accordance
with the
invention, for this purpose, a drilling apparatus 16 is first used to drill
vertically
through the layer 12, with a first, substantially vertical bore section 18,
down into the
oil sand deposit 14, and then, subsequent to the substantially vertical
section 18, a
substantially horizontal, second bore section 20 is disposed running within
the oil
sand deposit 14. This second, substantially horizontal bore section 20 is then
filled
sectionally, over a length indicated by means of the double-ended arrow 22,
with a
gellike explosive.
[0029]This gellike explosive is then detonated - see fig. 2. The underground
explosion within the oil sand deposit 14 causes the second, horizontal bore
section
20 to be enlarged in a radial direction, thus producing an underground cavern
24, as
shown in fig. 3. This underground cavern 24 runs substantially horizontally.
The walls
of the underground cavern 24 are composed of compacted oil sand, which as a
consequence of the underground explosion is displaced radially outward from
the
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bore section 20 and, as a result, compacted. The cavern 24 is therefore stable
and
communicates with the drilling apparatus 16 via the bore section 18.
[0030] In accordance with fig. 3, a second drilling apparatus 26 is used to
introduce a
third, substantially vertical bore section 28 through the layer 12 down into
the oil sand
deposit 14, which is then continued, as shown in fig. 1, through a fourth,
substantially
horizontal bore section. As elucidated using figs. 1 to 3, this fourth,
horizontal bore
section is then likewise filled sectionally with gellike explosive and then
enlarged by
the explosion of this gellike explosive. This produces a second underground
cavern
30 running substantially horizontally within the oil sand deposit 14. The two
underground caverns 24 and 30 are arranged substantially at the same height
within
the oil sand deposit 14, and run approximately parallel to one another. The
representation in fig. 4 is schematic, but is intended to show perspective,
and so the
two underground caverns 24 and 30 are arranged parallel to one another and
roughly
at the same height or same depth within the oil sand deposit.
[0031]Arranged beneath the two caverns 24 and 30 is a pumping pipe 32, which
communicates with a pumping station 34 on the Earth's surface 10.
[0032] Into both the underground cavern 24 and the underground cavern 30,
combustible material is next either introduced, or combustible material is
formed
within the caverns 24 and 30 by the introduction of additives, as for example
the
blown introduction of air. The combustible material then present within the
caverns 24
and 30, combustible gas for example, is then ignited by pyrotechnic means, for
example, so that combustion develops and a flame front propagates, starting
from
the two caverns 24 and 30. One such flame front is indicated in the case of
the
cavern with the reference numeral 36. The pressure produced as a result of the
combustion within the caverns 24 and 30 ensures a flow of gas in the direction
of the
arrows 38 and 40, in other words from the cavern 24 toward the cavern 30, and
in the
opposite direction. The oil sand deposit 14 consists of porous material, and
so
combustion and an associated flow of gas can propagate within the oil sand
deposit
14. The progress of the flame front 36 between the two caverns 24 and 30, with
a
flame front surrounding the cavern 24 not being shown, ensures heating of the
oil
sand situated between the two caverns 24 and 30, and, consequently, ensures
liquefaction of the bitumen situated between the two caverns 24 and 30. This
liquefied bitumen can then be pumped off via the bore 32; however, the
liquefied
bitumen will also collect within the caverns 24 and 30 and can then easily be
pumped
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off from these caverns. The same applies to gaseous hydrocarbon compounds,
which will preferably collect within the caverns 24 and 30.
[0033]Following depletion of the oil sand deposit 14 in the region between the
caverns 24 and 30, combustion can be extinguished by pumping CO2 into the
caverns 24 and 30. This CO2 will then spread, starting from the caverns 24 and
30
and likewise in the direction of the arrows 38 and 40, toward the respective
opposite
cavern 30 or 24, and the combustion of the oil sand deposit will be completely
extinguished as a result. This pumped introduction of CO2 may be used not only
to
extinguish the combustion but also, at the same time, for the permanent
storage of
CO2.
[0034]The representation in fig. 5 shows an arrangement of underground caverns
42, 44, and 46 in accordance with the method of the invention, in a further
embodiment. The caverns 42, 44, and 46 are arranged within the oil sand
deposit 14
and, as described with reference to figs. 1 to 3, are formed by arranging
first vertical,
then horizontal bore sections and then by enlarging the horizontal bore
sections by
inserting and detonating gellike explosive. Respective vertical bore sections
are
merely indicated in fig. 5 with the reference numerals 48. The vertical bore
sections
48 may be permanently sealed with concrete, for example. The representation in
fig. 5 is merely the schematic representation of the arrangement of the
underground
caverns 42, 44, and 46, but not of their production by the sinking of suitable
bores.
The vertical bore sections 48 should therefore be understood purely
schematically
and illustratively.
[0035]The underground caverns 42, 44, and 46 arranged horizontally, roughly at
the
same height, and parallel to one another within the oil sand deposit 14 are
connected
to one another by means of horizontal bores 50 and 52. The horizontal bore
sections
50 and 52 are arranged roughly flush and/or offset from one another and are
continued in the form of substantially vertically running bore sections 54 and
56 and
taken to pumping stations 58 and 60 at the Earth's surface. Starting from the
pumping station 58, a substantially vertical bore section 54 leads to the
cavern 42,
and is then continued by means of the bore section 50 to the cavern 44.
Starting from
the cavern 44, a flow connection exists via the bore section 52 to the cavern
46, and
from there the substantially vertical bore section 56 leads to the pumping
station 60.
The arrangement in fig. 5 shows the geometrical arrangement of the caverns 42,
44,
and 46 after the enlargement of corresponding bore sections by means of
explosive.
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[0036]The arrangement shown schematically in fig. 5 represents an underground
refinery. Accordingly, via the pumping station 58 and the bore section 54, air
and
other substances are introduced into the cavern 42. In the cavern 42 there is
a
combustion zone, and here, water is supplied, as well as air, in order, with
pyrolysis
coke, to form hydrogen and carbon monoxide (synthesis gas) for the
hydrotreating
and for the cracking of the hydrocarbon compounds from the oil sand deposit
14.
Upgrading of the bitumen, or cracking, takes place in the cavern 44. In the
cavern 46,
crude oil and light gas are deposited. Off-gas as well is collected in the
cavern 46,
and then off-gas, crude oil, and gaseous hydrocarbon compounds as well can be
pumped off via the pumping station 60. Within the cavern arrangement in fig. 5
there
is therefore a flow direction from the cavern 42 via the cavern 44 into the
cavern 46.
The cavern 42 forms a heating zone, the cavern 44 a conversion zone, and the
cavern 46 a suction-withdrawal or pumping-off zone.
[0037]The representation in fig. 6 shows an arrangement of underground bore
sections in accordance with the method of the invention, in a further
embodiment.
Three underground caverns 62, 64, and 66 are arranged here in parallel to one
another within an oil sand deposit, but also at different depth levels. The
caverns 62,
64, and 66 are connected to one another by bore sections 68 and 70. In the
cavern
62 there is a heating zone, in which combustion takes place. In the middle
cavern 64
there is a conversion zone, and in the uppermost cavern 66 there is a suction-
withdrawal zone. The embodiment of fig. 6 is intended for the exploitation of
gaseous
hydrocarbon compounds, and ensures quick combustion and quick conversion,
since
the light, gaseous hydrocarbon compounds will rise rapidly along the bore
sections
68 and 70 into the uppermost cavern 66, from which they can be pumped off.
This
predominant flow direction is indicated in fig. 6 by the arrow 72.
[0038] Fig. 7 shows an arrangement of underground bore sections in accordance
with
the method of the invention, in a further embodiment. Three underground
caverns 74,
76, and 78 are arranged parallel to one another but at different depths in the
oil sand
deposit, and are connected to one another by means of bore sections 80 and 82.
In
the uppermost cavern 74 there is a combustion zone, in the middle cavern 76
there is
a conversion zone, and in the lowermost cavern 78 there is a pumping-off zone.
A
predominant flow direction between the caverns 74, 76, and 78 is indicated by
means
of the arrow 84. The arrangement according to fig. 7 ensures slow propagation
of the
combustion gases, starting from the heating zone in the cavern 74. Liquid
hydrocarbon compounds will preferably collect in the lowermost cavern 78,
which
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they reach as a result of gravity. On account of the slow process, in which
the hot
combustion gases spend a long time in the respective regions of the oil sand
deposit,
good and thorough separation of light and heavy crude oil can take place.
[0039]The representation in fig. 8 shows an arrangement of underground bore
sections in accordance with the method of the invention, in a further
embodiment.
Three underground caverns 86, 88, and 90 are arranged parallel to one another
and
at different depths within an oil sand deposit. The cavern 86 on the left in
fig. 8 is
arranged the lowest, the cavern in the middle in fig. 8 the highest, and the
cavern on
the right in fig. 8 at a depth which lies roughly between the depths of the
caverns 86
and 88. The caverns 86 and 88 are connected by a bore section 92, which runs
upward at a slope, and the caverns 88 and 90 are connected by a bore section
94,
which runs downward at a slope.
[0040]In the deepest cavern 86, on the left in fig. 8, there is a combustion
zone,
which then propagates, as indicated with the reference numeral 96, within the
oil
sand deposit toward the middle cavern 88. As a result, in accordance with the
arrow
98, combustion gases rise preferably toward the middle cavern 88. The middle
cavern 88 represents a conversion zone and, since the pumping-off zone, in the
form
of the cavern 90 on the right in fig. 8, is situated lower than the middle
cavern 88, a
higher residence time is achieved in the conversion zone, corresponding to the
cavern 88.
[0041]The representation in fig. 9 shows the arrangement of the caverns 86,
88, and
90 from fig. 8, with the sealing of a connection between the cavern 88 and the
atmosphere being shown, by way of example, above the Earth's surface 10. A
connection 101 between the drilling apparatus 100 and the cavern 88 is then to
be
sealed, the connection 101 having served originally for the drilling of
connection 92.
For this purpose, an inflatable, elastic plug 102 is first introduced into the
bore,
adjoining the cavern 88, and is expanded using air, water, bentonite slurry,
or
flowable concrete, for example, until the bore section is fully filled and
thus sealed off.
This expandable plug 102 is then backfilled between the drilling apparatus 100
and
the plug 102, with sand, gravel, bentonite slurry, concrete or the like, for
example. A
connection between the cavern 88 and the atmosphere can be fully closed in
this
way. This can be done in order to produce defined flow conditions between the
caverns 86, 88, and 90 during operation. This may also take place after the
end of
the exploitation of the oil sand deposit. For example, after the end of
exploitation,
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CO2 is passed into the caverns 86, 88, and 90 in order to halt the combustion
and to
a certain extent to deposit CO2. After introduction of the plug 102 and the
backfilling
104, the caverns 86, 88, and 90 are then separated from the atmosphere, and so
the
deposited CO2 is no longer able to escape.
[0042]The representation in fig. 10 shows a further arrangement of underground
bore sections in accordance with the method of the invention, in a further
embodiment. Arranged beneath the Earth's surface 10 and within an oil sand
deposit
14 there is a matrix of bore sections, which exhibits a total of four planes
106, 108,
110, and 112 at in each case eight caverns arranged parallel to one another
and at
the same height. The number of four planes and also the number of in each case
eight caverns arranged parallel to one another and at the same height is
merely
exemplary. The caverns in each plane 106, 108, 110, and 112 are each connected
to
one another by means of a horizontal bore 114, 116, 118, and 120.
[0043]The arrangement of underground bore sections and caverns shown in fig.
10
forms an underground refinery, by means of which it is possible not only to
exploit the
oil sand deposit 14 but also, at the same time, to convert the hydrocarbon
compounds still within the oil sand deposit 14.
[0044]The representation in fig. 11 shows an arrangement of underground bore
sections in accordance with the invention, in a further embodiment.
[0045]According to fig. 11, three vertical bores 122, 124, and 126 have been
introduced in parallel to one another in the Earth's surface 10 down into the
oil sand
deposit 14. Bore sections situated within the oil sand deposit 14 have been
enlarged
by explosion, thus forming three vertically arranged underground caverns 128,
130,
and 132. In the region of their top end, the underground caverns 128, 130, and
132
are connected to one another by means of horizontally running bores 134 and
136,
and in the region of their lower end by means of horizontal bores 138 and 140.
The
caverns 128 and 130 communicate via the bores 134 and 138, and the caverns 130
and 132 communicate with one another via the bores 136 and 140. An arrow 142
symbolizes the introduction of air or other substances into the cavern 128 on
the left
in fig. 11. This is done via one or more bores, which for clarity are not
shown in
fig. 11. The pumping-off of liquid hydrocarbon compounds from the cavern 132
on the
right in fig. 11 is indicated by means of an arrow 144. Liquid hydrocarbon
compounds
collect in the cavern 132, in accordance with gravity, at its bottom end, and
so liquid
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hydrocarbon compounds are also pumped off from there. The pumping-off of
gaseous hydrocarbon compounds from the cavern 132 is indicated by means of an
arrow 146. Gaseous hydrocarbon compounds collect in the cavern 132 preferably
in
the region of its upper end, and so gaseous compounds are also pumped off from
there.
[0046] The arrangement of the underground caverns 128, 130, and 132 that is
shown
in fig. 11 also forms an underground refinery with a heating zone in the
region of the
left-hand cavern 128, a conversion zone in the region of the middle cavern
130, and
a pumping-off zone in the region of the right-hand cavern 132.
