Oil shale is a hydrocarbon bearing rock from which technology can extract petroleum-like oil. Worldwide oil shale deposits are estimated to contain 2.8-3.3 trillion barrels of oil equivalent, of which the majority (2 trillion barrels) is located in the United States. The richest, most concentrated US oil shale deposits are located in Colorado, Utah and Wyoming. These deposits contain approximately 1.2 trillion barrels.
Current oil shale conversion technologies
Basically, there are two types of oil shale conversion methods, i.e., surface retorting and in-situ process.
Surface retorting consists of three steps: 1) oil shale mining and preparation; 2) pyrolysis of oil shale; 3) oil refinery.
There are two different surface retorting facilities, vertical and horizontal. Vertical retorts heat the oil shale in a vertical vessel. Examples of vertical retorts include Paraho, Petrosix, Fushun, Kiviter. Horizontal retorts heat the oil shale through a horizontal kiln. Examples of horizontal retorts include TOSCO II, ATP, Galoter.
In-situ process involves no mining. It is feasible for deeper, thicker deposits, not as amenable to surface or deep mining methods.
The most well-known in-situ process is Shell ICP. In this process, a freeze wall is first to be constructed to isolate the processing area from surrounding groundwater. The process releases oil and gas from the oil shale by in-situ heating. The oil and gas then is pumped to the surface using traditional methods.
AuraSource, Inc. uses a proprietary low-temperature catalytic process (AuraFuelTM Process) for oil recovery from oil shale. AuraFuelTM process is an above-ground retorting technology, which has simple and robust design, energy self-sufficiency, minimal water usage, and high oil yields. By weight of raw oil shale, the oil yield of this technology is as high as 21-28% and it can produce 8-15% of petroleum dry gas to substitute natural gas.