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25 Cards in this Set
- Front
- Back
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Oil Shale |
fine grained sedimentary rock that yields oil on heating |
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Tar Sands v. Oil shales |
in tar sand the oil is free and occurs within pores. in oil shales, oil seldom occurs free, but is contained within the complex structure of kerogen, from which it may be distilled. |
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Chemical composition of oil shales |
inorganic components : - Detrital----Quartz, Feldspar, Mica, Accessory minerals, Carbonates, Clays, and Pyrite - Authigenic - Carbonates, Clays, and Pyrite Organic Components: - bitumens around 2% -Kerogens around 8% |
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Distribution of oil shale |
occurrence & distribution of oil shale are widespread in place & time |
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Precambrian oil shales |
only a few in existence |
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Early Paleozoic |
siliceous oil shales were deposited on marine shelves throughout the Northern Hemisphere |
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Late Paleozoic |
oil shales were deposited on marine shelves in central European Russia and in the central & eastern US and Canada. |
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Devonian-Carboniferous boundary |
oil-shale-forming environments appear to have changed significantly. |
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Major depositional environments favorable for oil |
- Lakes - Fluvially dominated deltas - Certain marine shelves |
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Permian period |
both paralic & marine shales are formed. |
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Tight Natural Gas |
gas stuck in a very tight formation underground trapped in a rock that is usually impermeable and non-porous. |
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Conventional Natural Gas Deposit |
once drilled gas can be usually extracted quite readily and easily |
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Shale gas |
natural gas produced from shale. Shales ordinarly have insufficient permeability to allow significant fluid flow to a well bore. Most shales are not sources of natural gas. |
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Fracking |
new technique of horizontal hydraulic fracturing. The "frack" is a formation that the shale drillers put into the cracks in order to help split the rock. |
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Shale gas production methods |
- horizontal drilling and hydraulic fracturing - produced from horizontal, rather than vertical wells into hard rock deposits |
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Shale gas characteristics
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high calorific value and commonly wet with less than 10% ethane. |
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Shale gas exploitation |
not profitable. the reserves are too small and payout time too long |
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Distribution of shale gas |
controlled by quantity, quality, and level of maturation of organic matter in shale formations |
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Fracture Systems |
located by remote sensing and seismic surveys. Best developed where strata are stretched over crests of anticline or along regional fault and basin hinge line trends. |
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Air Drilling |
used to find shale gas. |
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Transportation Shale Gas |
Seldom feasible because of the low pressure the gas must be pressurized for it to flow along a pipeline. |
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Shale gas production feasibility |
negligible environmental impact. once the well is drilled there is no derrick. Production is modest but reliable, quiet, and long term. |
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Coal bed gas |
form of natural gas extracted from coal beds. Methane is adsorbed into the solid matrix of the coal. |
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Coal bed methane (CBM) |
coals only produce dry gas, methane. coal bed gas has a lower calorific value than shale gas. Coal beds normally have more fractures and higher permeability. |
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Micro-seismicity monitoring |
monitoring in oil/gas reservoirs is an effective way to assess the effects of fluid injections and reservoir properties. - used to image hydraulic fracture simulations and distributions |
