Search results
Results from the WOW.Com Content Network
Oil shale formation takes place in a number of depositional settings and has considerable compositional variation. Oil shales can be classified by their composition (carbonate minerals such as calcite or detrital minerals such as quartz and clays) or by their depositional environment (large lakes, shallow marine, and lagoon/small lake settings).
The fine particles that compose shale can remain suspended in water long after the larger particles of sand have been deposited. As a result, shales are typically deposited in very slow moving water and are often found in lakes and lagoonal deposits, in river deltas, on floodplains and offshore below the wave base. [13]
The largest deposits are found in the remains of large lakes such as the deposits of the Green River Formation of Wyoming and Utah, USA. Large lake oil shale basins are typically found in areas of block faulting or crustal warping due to mountain building. Deposits such as the Green River may be as much as 2,000 feet (610 m) and yield up to 40 ...
A 1984 study estimated the EROI of the various known oil-shale deposits as varying between 0.7–13.3, [75] although known oil-shale extraction development projects assert an EROI between 3 and 10. According to the World Energy Outlook 2010, the EROI of ex-situ processing is typically 4 to 5 while of in-situ processing it may be even as low as 2.
The Messel lake bed was probably a center point for drainage from nearby rivers and creeks. A fossil of the primitive mammal Kopidodon, showing outline of fur. The pit deposits were formed during the Eocene Epoch of the Paleogene Period about 47 million years ago, based on dating of basalt fragments underlying fossilbearing strata. [6]
The unusual chemistry of the lakes in which it was deposited makes the Green River Formation a major source of sodium carbonate. In southwest Wyoming the formation contains the world's largest deposits of trona, and in Colorado, the world's largest deposits of nahcolite. [19]
Source rocks are classified from the types of kerogen that they contain, which in turn governs the type of hydrocarbons that will be generated: [1]. Type I source rocks are formed from algal remains deposited under anoxic conditions in deep lakes: they tend to generate waxy crude oils when submitted to thermal stress during deep burial.
Approximately 30% of the world's oil is found in these shale deposits. Although the origin of these deposits is still under study, it has been established that the shale routinely overlies glacial and glacio-marine sediment deposited ~445 million years before the present by the Hirnantian glaciation. The shale has been linked to glacial ...