Mining or in situ disintegration of hard material – With separation of materials – Separation below surface of earth or water
Reexamination Certificate
2001-03-05
2003-04-29
Bagnell, David (Department: 3673)
Mining or in situ disintegration of hard material
With separation of materials
Separation below surface of earth or water
C299S019000, C299S018000, C299S056000, C299S001300, C405S146000
Reexamination Certificate
active
06554368
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to the mining and/or processing of soft-ore deposits generally and to the mining and/or processing of bitumen-containing materials, such as oil sands, specifically.
BACKGROUND OF THE INVENTION
Oil is a nonrenewable natural resource having great importance to the industrialized world. Over the last century, the consumption of oil has increased dramatically and has become a strategic commodity, leading to the development of alternative sources of crude oil such as oil sands and oil shales. As used herein, oil sands are a granular or particulate material, such as an interlocked skeleton of sand, with pore spaces occupied by bitumen (an amorphous solid hydrocarbon material totally soluble in carbon disulfide), and oil shale is a rock containing kerogen (a carbonaceous material that which gives rise to crude oil on distillation). The vast majority of the world's oil sands deposits are found in Canada and Venezuela. Collectively, oil sands deposits contain an estimated 10 trillion barrels of in-place oil. Oil shales are found worldwide with large deposits in the U.S. Collectively, oil shale deposits contain an estimated 30 trillion barrels or more of in-place oil. It is to be understood that a reference to oil sands is intended to include oil shales and vice versa.
Bitumen is typically an asphalt-like substance having an API gravity commonly ranging from about 5° to about 10° and is contained within the pore space of the oil sands. Bitumen cannot be recovered by traditional oil well technology because it will not flow at ambient reservoir temperatures. To overcome this limitation, near surface oil sand deposits are excavated by surface mining methods, while bitumen in deeper deposits is recovered by in situ techniques, which rely on steam or diluents to mobilize the bitumen so that it can be pumped out by conventional oil recovery methods. The bitumen is recovered from the surface excavated oil sands by known separation methods, and the bitumen, whether derived from surface mining or in situ processes, sent to upgrading facilities where it is converted into crude oil and other petroleum products. Underground mining techniques have been largely unsuccessful in mining deeper oil sands due to high mining costs and unstable overburden conditions.
Existing methods for recovering oil from oil sands have numerous drawbacks. Surface mining techniques are typically only economical for shallow oil sands deposits. It is common for oil sands deposits to dip and a significant part of the ore body may be located at depths that are too deep to recover by surface mining methods. As a result, most of the oil sands deposits are unprofitable to mine. Surface mining requires large areas to be stripped of overburden which then must be moved to other areas for storage. The tailings from the bitumen separation process typically require large tailings ponds complexes in which the tailings are treated before the mined land can be reclaimed. The costs of stripping overburden, building and maintaining tailings ponds and eventual land reclamation costs can be high, particularly for deeper oil sands deposits. Because of the large scale of these operations, the short and long term environmental impact and associated costs of surface mining can be substantial. In situ techniques are disadvantaged in that a relatively large amount of energy is consumed per unit energy recovered in the bitumen.
A significant portion of oil sands deposits lie too deep for economical recovery by surface mining and are too shallow for effective in-situ recovery. Other oil sands deposits, though located at shallow depths, are located under surface features that preclude the use of surface mining. For example, oil sands deposits can be located under lakes, swamps, protected animal habitats and surface mine facilities such as tailings ponds. Estimates for economical grade bitumen in these in-between and inaccessible areas range from 30 to 100 billion barrels.
SUMMARY OF THE INVENTION
These and other needs are addressed by one or more of the various inventions discussed herein. Certain of the inventions relate to excavating materials, particularly soft-ore or sedimentary materials, by underground mining techniques. The material excavated by these methods can be any valuable material, particularly in-situ or in-place hydrocarbon-containing materials, such as found in oil sands, oil shales, conventional oil reservoirs, coal deposits and the like, as well as other valuable minerals such as bauxite, potash, trona and the like.
In a first embodiment, the present invention provides an underground mining method in which the material is excavated, continuously, semi-continuously, or episodically, by an underground mining method such as a continuous mining machine, drill-and-blast, longwall mining, hydraulic mining, mechanical excavation whether by backhoes, hydraulic hammers and the like, or by tunnel boring machines (“TBMs”) or any other appropriate underground mining practice. A movable shield may be used to provide ground support over the mining apparatus and personnel during excavating. In one configuration, a substantially smaller tunnel liner is formed within the excavation shield and left in place behind the moveable excavation shield as it advances. A backfill material is placed in the excavated volume behind the excavation machine and around the access tunnel liner. Preferably, the backfill at least substantially fills the unsupported volume and itself is supported by the tunnel liner and, in part, by the excavation shield and/or a bulkhead. Typically, the backfill (i.e., the solid particulates and associated interstitial or interparticle spaces) fills at least about 65%, more typically at least about 75% and even more typically from about 85 to about 100% by volume of the space defined by the access tunnel liner, the mining machine bulkhead, the bulkhead (or backfill retaining member) at the excavation entry, and the surrounding excavation. The excavation shield, bulkhead, backfill material and/or tunnel liner all act to support the unexcavated ground behind the excavation face. This combination provides ground support for the mining operation and a small trailing tunnel or passage for ingress and egress from the working face. The backfill material can be tailings from material processing operations, previously mined material, currently mined material, or any other material having acceptable density and strength characteristics.
The backfill operation can be accomplished by numerous techniques. For example, a prefabricated liner having a smaller outer boundary than the surface of the excavation can be set in place anywhere behind a rear section of the movable shield, and, before, during, or after advancement of the shield, the backfill material is injected or otherwise placed in the gap or space between the liner, the machine bulkhead, previously backfilled material, and the surrounding excavated opening. The trailing tunnel is defined by and extends through the liner.
In another configuration, the liner is formed beneath the shield such as using a suitable form, and the lining material placed in or on the form and allowed to set or become self-supporting while the overlying shield is in position. The liner can be formed from any suitable, preferably consolidated, material, such as concrete, grout, asphalt, or a combination thereof. The lining material could include previously excavated material, whether or not processed for bitumen recovery. When the liner is formed, the backfill material can be placed in the gap by suitable techniques. Before injection into the open space above the liner, the excavated backfill material could be combined with a suitable binder, such as flyash, gypsum, sulphur, slag, and the like, which will consolidate or strengthen the backfill material after injection into the open space.
In another configuration, the access tunnel is formed without a liner by combining the backfill material with a binder, such as those described above, placing the backfi
Drake Ronald D.
Kobler Michael Helmut
Watson John David
Bagnell David
Kreck John
Oil Sands Underground Mining, Inc.
Sheridan & Ross P.C.
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