Apparatus for the in-situ retorting of carbonaceous deposits includes a plurality of retorts connected to a common exhaust tunnel effectively free of broken shale into which products of the retorting are discharged. To allow simultaneous mining, rubblization and retorting of the in-situ retorts, the exhaust tunnel is provided with doorways between the retorts. Doors movable in the exhaust tunnel are adapted to seal against the doorways to prevent flow from retorts in which retorting is in progress to retorts under construction. A trench in the exhaust tunnel is provided for flow of liquid products produced in the retorting. A liquid seal under the doorways communicates with the trench to provide a passage for liquid flow past the doorways and to prevent upstream flow of gaseous products through the passage for the liquid flow.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the in-situ retorting of carbonaceous deposits, 
and more particularly to apparatus for control of the flow of products 
produced during the in-situ retorting of such deposits. 
2. Description of the Prior Art 
Very large potential sources of fluid fuels exist in subsurface deposits of 
carbonaceous materials that are either solid materials or so highly 
viscous that they cannot be made to flow through the subsurface formation 
to a production well. Among such deposits are oil shale, tar sands and 
coal. One method of producing fluid fuels from such deposits is to ignite 
the deposits and continue after ignition to inject an oxygen-containing 
gas, usually air, into the deposits to burn some of the carbonaceous 
material. If an in-situ combustion process is utilized for production of 
shale oil from oil shale, the shale is heated to a temperature at which 
kerogen in the oil shale is converted to shale oil which is then made to 
flow to facilities for lifting the shale oil to the surface. In-situ 
combustion of tar sands raises the temperature of the sands to a 
temperature at which the oil has a viscosity sufficiently low to allow it 
to flow to production facilities. Cracking of the oil further reduces its 
viscosity, and the pressure of the injected air drives the oil toward the 
production well. The maintenance of combustion in coal deposits is 
designed principally to convert carbon in the coal to gaseous materials, 
principally carbon monoxide, which can be used as a fuel. 
Shale deposits, coal deposits, and some of the tar sands have a 
permeability that is so low that even if the carbonaceous material is 
converted to fluids, flow to a production facility at a rate high enough 
to continue the combustion cannot be maintained. One method that has been 
proposed to overcome the low permeability of the carbonaceous deposit is 
to form rubblized in-situ retorts of the carbonaceous deposit. Several 
suitable processes for the formation of rubblized in-situ retorts and the 
production of fluid fuels therefrom are described in U.S. Pat. No. 
1,919,636 of S. N. Karrick, U.S. Pat. No. 3,001,776 of H. K. Van Poollen 
and U.S. Pat. No. 2,481,051 of L. C. Uren. Rubblized retorts can be used 
for in-situ combustion processes and also for other retorting schemes such 
as injection of hot flue gases or steam into the retort. 
In the systematic exploitation of a subsurface deposit of a material such 
as oil shale, retorts are constructed in rows and retorting of rubblized 
shale is conducted in one or more of the retorts in the row while 
construction of other rubblized retorts in the row is proceeding. The 
gaseous products produced in the in-situ combustion operations are highly 
toxic. It is important to isolate retorts under construction from retorts 
in which combustion is in progress. In a preferred method of preventing 
flow of combustion products from a retort in which combustion is in 
progress through fissures or fractures in the carbonaceous deposit to a 
retort in which men are working, a rubblized retort between the combustion 
and mining retorts is maintained under air pressure higher than the 
pressure in both the retorts in which combustion is in progress and the 
retorts in which men are working. 
SUMMARY OF THE INVENTION 
This invention resides in an exhaust tunnel and a movable door structure 
serving a plurality of in-situ retorts. The exhaust tunnel is for delivery 
of products produced during in-situ retorting to collection and lifting 
apparatus for delivering the products to the ground surface. The structure 
of this invention allows closing of the tunnel between retorts to allow 
isolation of retorts in which men are working from products produced in a 
retort in which retorting is in progress. Doorways in the exhaust tunnel 
are engaged by a door that can be moved from one doorway to the next to 
seal against the doorway to close the tunnel. In a preferred embodiment, 
two movable doors are provided in the exhaust tunnel to allow 
pressurization of a rubblized retort between a retort in which retorting 
is in progress and a retort in which mining is in progress. Preferably, 
the exhaust tunnel is provided with a trench for draining liquid products 
produced in the retorting. A liquid seal under the doorways provides a 
continuation of the trench past the doorways without allowing flow of gas 
past the doorway.

DESCRIPTION OF PREFERRED EMBODIMENT 
For convenience in description, this invention will be described for use in 
the in-situ retorting of oil shale. Referring to FIG. 1 of the drawings, a 
row of in-situ retorts 10, 12, 14, 16, 18, 20, 22 and 24 in a subsurface 
oil shale deposit are separated by end pillars 26, 28, 30, 32, 34 and 36. 
During the construction of the retorts and preferably before initiating 
the in-situ combustion in any of the retorts, an exhaust tunnel 38 is 
driven below one side of the retorts for the length of the row at or 
slightly below the level of the bottom of the retorts. A withdrawal drift 
40 is driven parallel to the exhaust tunnel at the opposite side of the 
retorts. The exhaust tunnel and withdrawal drift are used in the mining 
and hauling of shale and for ventilation during construction of the 
retorts, and it is for that reason the exhaust tunnel and withdrawal drift 
are preferably driven for the length of the tunnel before beginning 
combustion in any of the retorts. 
Exhaust tunnel 38 extends beyond retort 10 to a collection tunnel 42 
through which products of the retorting are delivered, preferably to a 
separator, not shown, before delivery to the surface. Flow in the tunnel 
38 is toward collection tunnel 42. In the description, the direction 
toward tunnel 42 is referred to as downstream and the direction away from 
tunnel 42 is referred to as upstream. A plurality of collars 44 are driven 
from the collection tunnel 42 at intervals along its length for connection 
to exhaust tunnels from rows of retorts to be constructed later. A 
stationary door 46 that can be opened or closed by remote control and a 
movable door 48 of the type to be described hereinafter is installed in 
each collar before the beginning of in-situ combustion in any retort that 
delivers products into collection tunnel 42. Each of the collars 44 is 
sealed with fill behind the doors 48. After rubblization of a retort is 
completed, the withdrawal drift 40 is sealed as indicated by seals 50 
between that retort and the adjacent retort in which mining or 
rubblization activities are continuing. 
The retorts shown in FIG. 1 are in various stages of operation. Combustion 
has been completed in retort 10, burning is progressing in retort 12, 
retort 14 has been rubblized and is pressurized with air, retort 16 is in 
the process of being rubblized, and retort 18 is in a stoping phase 
preparatory to rubblization. Retorts 20, 22 and 24 have yet to be 
constructed. Eight retorts have been shown in the row served by tunnel 38, 
but that number is only for illustration of the invention. Either more or 
fewer retorts can be in the row. 
The retort shown in FIG. 2 is of a preferred configuration in which the 
exhaust tunnel is laterally displaced from the retort outlet. The retort 
is of a rectangular horizontal section and typically may have a width of 
150 feet and a length of 300 feet. The height of the retort will, of 
course, depend on the thickness of the oil shale deposit. In the Piceance 
Creek region of Colorado, the thickness of the shale deposits is such that 
the retorts may be 700 feet or more in height. The roof 52 of the retorts 
slopes upwardly from the sides to an apex tunnel 54. Air for the 
combustion operation is delivered into the apex tunnel 54 through an air 
supply tunnel 56. The bottom 58 of the retort slopes downwardly from the 
lower end of one side to an outlet 60 at the bottom of the opposite side 
that communicates with a plurality of product drifts 62 that extend 
laterally from the outlet to the exhaust tunnel 38. Exhaust tunnel 38 must 
be unobstructed to allow movement of the doors as the retorting progresses 
in series to upstream retorts. If the exhaust tunnel is directly below the 
outlet of the retorts, means must be provided to prevent shale falling 
into the exhaust tunnel where it would prevent the movement of the doors 
as required for retorting in the upstream retorts. Retort 12 is shown in 
FIG. 2 in the burning stage with a combustion front 64 indicated 
schematically by a plurality of vertical lines. 
The exhaust tunnel 38 slopes downwardly at a slight angle such as 3 to 8 
degrees from retort 24 to the collection tunnel 42 to facilitate drainage 
to the collection tunnel of any liquid products that collect in the 
exhaust tunnel. As is best shown in FIG. 4 of the drawings, the bottom of 
the exhaust tunnel 38 also slopes downwardly at a slight angle from its 
sides to a trench 66 in which liquids collect and drain to the collection 
tunnel 42. Trench 66 minimizes contact between liquids and gases in 
exhaust tunnel 38, thereby minimizing entrainment of liquids in the gases, 
and connects with a similar trench, not shown, in tunnel 42. Extending 
longitudinally of the exhaust tunnel 38 are parallel runways 67 that 
provide a smooth surface slightly above the floor of the tunnel 38 over 
which the doors can be skidded, as hereinafter described. Transverse 
drains through, or short gaps in, the runways are provided to allow oil to 
drain to trench 66. Located at intervals in the exhaust tunnel 38 at 
positions to allow isolation of each retort from an adjacent retort are 
doorways 68. The doorways 68 are preferably located where the exhaust 
tunnel penetrates the pillars 26, 28, 30, etc. between adjacent retorts 
because of the increased stability at the pillars as compared to under the 
retorts. The doorways could be located at any place in the exhaust tunnel 
38 between the upstream product drift 62 of one retort and the downstream 
product drift 62 of the adjacent upstream retort. 
The doorways 68 are essentially concrete collars that extend inwardly from 
the wall around the periphery of the exhaust tunnel to provide a smooth 
surface that permits a tight seal to prevent flow of gaseous combustion 
products from a retort in the process of burning to the adjacent rubblized 
retort, as hereinafter described. The collars preferably extend inwardly 
for approximately one foot from the walls of the exhaust tunnel to provide 
adequate clearance between the tunnel walls and the doors 48 to allow 
movement of the doors through tunnel 38. For example, if an exhaust tunnel 
is 22 feet wide by 20 feet high, the opening of the doorway can be 20 feet 
in width and 18 feet high. The sill 69 of the doorway is slightly, for 
example 1/2 inch to 1 inch, above the upper surface of the runways 67. To 
provide a continuation of the trench 66, an oil drain seal 70 extends from 
the trench 66 on one side of the doorway under the doorway to the trench 
66 on the other side of the doorway, as is best shown in FIG. 6 of the 
drawings. Seal 70 has a suitable depth, for example 12 feet, to provide a 
seal that will not be blown out at the pressure differentials across the 
doorway that are likely to be encountered. The diameter of the seal 70 
should be larger than the width of the oil drain to eliminate the 
possibility of blockage by debris carried into the oil from the oil drain. 
As is best shown in FIG. 6, the doors 68 consist essentially of a barricade 
71 mounted on a sled 72 that is adapted to be pulled through tunnel 38 by 
a tugger hoist. The sled 72 has a a pair of spaced-apart front runners 74 
and rear runners 75 positioned to skid on the runways 67 as the door is 
moved from one doorway to the next. Extending around the barricade 71 
portion of the door are a plurality of inflatable sealing rings 76 of 
rubber or other flexible material which, for example, may be expanded by 
gas or hydraulic pressure from a relaxed height of three inches to an 
expanded height of six inches to engage the surface of the doorway to 
provide the necessary seal. Doors 48 are provided with bumpers 80 at their 
upstream end for engagement with guide plates 77 in the doorways to center 
the doors in the doorways. While a door at the doorway immediately 
upstream of the retort in which retorting is in progress would suffice to 
close the exhaust tunnel to upstream flow of combustion products, it is 
also desirable to use the doors to isolate a retort adjacent a retort in 
which burning is in progress to permit pressurization of that retort. Two 
doors 48 in the exhaust tunnel 38, one at each end of the pressurized 
retort, allow the desired pressurization. The two doors are essentially 
identical except that the downstream door designated as 48a will be 
exposed to hot combustion products and must be cooled. A coolant is 
circulated through that door from the upstream door designated as 48b. 
Similarly, means for controlling the seals 76 in door 48a and for moving 
door 48a are operated from upstream of door 48b and pass through that 
door. 
Referring to FIGS. 1 and 3, doorways adjacent pillars 26, 28, 30, and 32 
are indicated by reference numerals 68a, 68b, 68c and 68d for convenience 
in the description of the operation of this invention. The doorways can be 
constructed at any time up to the pressurization of an adjacent retort. 
Door 48a is shown in the exhaust tunnel 38 in doorway 68b at pillar 28 and 
the door 48b is shown in tunnel 38 at doorway 68c adjacent pillar 30. The 
portion of tunnel 38 upstream of door 48b will be exposed to a 
substantially atmospheric environment in which men can work. That portion 
of the tunnel between the two doors 48a and 48b will contain air under 
pressure and that portion of the tunnel opposite retorts 10 and 12 will 
contain combustion products. To cool the door 48a that is exposed to the 
combustion products, a cooling medium circulating means indicated by line 
82 extends from door 48b to door 48a, as is shown in FIG. 3. Similarly, 
pneumatic or hydraulic fluid supply means indicated by line 84 extend from 
door 48b to door 48a to supply air for expanding seal 76 in door 48a. The 
single lines 82 and 84 are diagrammatic representations and can designate 
conduits for delivery of fluids to door 48a and returning the fluids to 
door 48b. Cooling medium circulating means 82 is connected with a suitable 
supply of cooling medium indicated by 86 to the right of door 69b in FIG. 
3. Similarly, means for supplying fluid to inflate the sealing means 76 
are indicated by 88 located in the exhaust tunnel 38 upstream of door 69b 
in FIG. 3. Valves, pumps and switches needed to control flow in lines 82 
and 84 are provided and considered to be included in 86 and 88. Means, not 
shown in the drawing, are provided in door 48b sealing around lines 
extending from door 48b to door 48a to prevent leakage through the door. A 
tugger hoist 90 movably located in tunnel 38 upstream of door 48b in FIG. 
3 is connected to that door by a cable 92. An extension 94 of cable 92 is 
connected to door 48a for movement of that door, as hereinafter described. 
In the operation of this invention, tunnel 38 is driven to connect with the 
collection tunnel 42. If the row of retorts shown in FIG. 1 is not the 
first row of retorts to produce products delivered into collection tunnel 
42, exhaust tunnel 38 will be driven to connect with a previously 
constructed collar similar to collars 44. Remote-controlled door 46 is 
opened. For the first retorting in the row of retorts, door 48a is moved 
to close the doorway 68a immediately upstream of retort 10 and door 48b is 
moved into doorway 68b before ignition of retort 10. The oil drain seal in 
each of the doorways is filled with liquid before the door is in place. 
The retorting of the oil shale in the retorts is conducted by conventional 
techniques. If in-situ combustion is used to supply the heat necessary to 
retort the oil shale, a fuel and air are injected into the top of the 
retort and the fuel is ignited. Injection of the fuel and air are 
continued until the oil shale is ignited and thereafter the injection of 
the fuel is discontinued but the flow of air is continued. A combustion 
front such as 64 is developed. Hot gases from the combustion front flow 
downwardly through oil shale below the combustion front to heat the shale 
to a temperature such as 800.degree. F. to 1000.degree. F. at which 
kerogen in the oil shale is converted to shale oil. A carbonaceous residue 
is left on the oil shale immediately below the combustion zone. That 
residue serves as the fuel burned in the combustion zone. Shale oil and 
gaseous combustion products flow downwardly through the retort to its 
outlet and then through the product drifts 62 to the exhaust tunnel 38 for 
delivery to the collection tunnel 42. 
Assuming, for purposes of description, that, as shown in FIGS. 1 and 3, 
retort 10 is spent and retort 12 is burning, door 48a will be in doorway 
68b adjacent pillar 28 and door 48b will be in doorway 68c adjacent pillar 
30. The doors 48a and 48b are positioned in the doorway with the front and 
rear runners straddling the sill of the doorway to allow the seals to 
engage the sill. Contraction of the seals on deflation provides adequate 
clearance for moving the doors through the doorway. After completion of 
the burning in retort 12, the seals on door 48b are deflated and that door 
is pulled by tugger hoist 90 and cable 92 to a position in doorway 68d. 
During the movement of door 48b, door 48a remains closed in doorway 68b. 
To allow movement of door 48b independently of door 48a, it is necessary 
that the lines 82 and 84 and cable 94 have slack between their connection 
to door 48b and their connection to door 48a as the distance between the 
doors will be doubled during the movement of the doors. When door 48b is 
in position in doorway 68d, the seals in doors 48b are expanded and 
thereafter the seals on door 48a are released and door 48a moved to 
position in doorway 68c. The seals in door 48a are then expanded, after 
which retort 16 is pressurized and burning is commenced in retort 14. The 
procedure is repeated after burning is completed in each retort to move 
the doors to retorts successively farther from the collection tunnel until 
all of the retorts in the row have been retorted. After retorting has been 
completed in retort 22, door 48b will be removed from the tunnel 38, door 
48a will be moved to a doorway in tunnel 38 at the upstream end of retort 
24, and a seal similar to seal 50 constructed on the upstream side of door 
48b. Retort 24 will then be retorted in the manner described above. 
It has been proposed that the retorting of oil shale be conducted under a 
pressure ranging from a slight vacuum to a pressure exceeding atmospheric 
pressure. In either type of operation, the large area of the doors 48 may 
generate a large force tending to move the doors in the exhaust tunnel 
even though the pressure differential across the door is low. If the force 
exerted by the seals 76 against the doorway and the weight of the door is 
believed not to be adequate to hold the doors in place, locking means can 
be provided to prevent movement of the doors. 
Referring to FIG. 8 of the drawings, an embodiment of this invention is 
shown in which a notch 96 is provided in the doorway. Mounted on the door 
48 is a cylinder 98 in which a piston 100 is slidable. A hydraulic or 
pneumatic fluid supply line 102 extends from the barricade 70 of the door 
to move the piston 100 as desired. For example, piston 100 may be urged by 
a spring toward an extended position engaging notch 96 and moved into a 
retracted position by a fluid supplied by line 102. When the door is moved 
into position for sealing against the doorway, the spring will move piston 
100 into notch 96. When it is desired to move the door to the next 
doorway, a fluid under pressure is supplied to cylinder 98 to retract 
piston 100, the seals 76 deflated, and the door moved to the next doorway. 
When the door is adjacent the next doorway, the pressure within cylinder 
98 will be released and the piston 100 moves outwardly into the notch 96 
to lock the door in position. A single notch 96 and piston 100 have been 
shown in FIG. 3. Preferably a plurality of such pistons will extend into a 
notch 96 that extends around the doorway or into individual notches 
located at intervals around the door. 
This invention allows the use of a single tunnel to deliver products of 
in-situ retorting in a bank of retorts. It also permits retorting, mining 
and rubblization to proceed simultaneously in retorts connected to a 
single exhaust tunnel. The preferred embodiment further allows maintenance 
of a rubblized retort between retorts in which combustion is in progress 
and retorts in which men are working at a higher pressure than in either 
of such retorts to provide a positive gas pressure barrier to prevent 
leakage of combustion products through fissures or fractures in the oil 
shale deposit to retorts in which men are working as well as through the 
exhaust tunnel. 
This invention has been described for the in-situ retorting of oil shale by 
combustion in an in-situ retort of a portion of the organic material in 
the oil shale, but is not limited to such use. The invention has utility 
wherever in-situ retorting of a carbonaceous deposit, which may be a heavy 
crude oil in a formation of low permeability or coal as well as oil shale, 
is conducted in a plurality of retorts connected to a common exhaust 
tunnel into which products of the retorting are discharged.