File:Oil investigations in 1917 and 1918 (1919) (14586999150).jpg

Identifier: oilinvestigation40illi (find matches)
Title: Oil investigations in 1917 and 1918
Year: 1919 (1910s)
Authors: Illinois State Geological Survey Barrett, Nellie Okla, 1895- Nebel, Merle Louis, 1892-1918 Coryell, Horace Noble, 1888- Tough, Fred H Williston, Samuel H Savage, Thomas Edmund, 1866-
Subjects: Petroleum
Publisher: Urbana
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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mined at numerous points, it will be found higherat some places than at others. If enough elevations are determined,areas can be located in which the rocks have been arched up into lowanticlines or domes. Careful studies have shown that all of the rocksunder this region lie approximately parallel to each other, so that if asingle bed is found to be arched up, it is safe to assume that the under-lying rocks are arched up in the same manner and at the same place.Moreover, it has been shown that the larger part of the folding in thisregion took place after the deposition of the Coal Measures orPennsylvanian rocks, so that No. 2 coal, for example, is probably foldedabout as much as the Niagaran limestone or other rocks several hundredfeet below. It is true that the region oscillated above and below sea levelseveral times during the deposition of these rocks, and erosion took placeduring periods of emergence so that the planes of contact between differ- 42 OIL INVESTIGATIONS Ist.drill hole
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Pig. 14. Diagrams showing conditions governing oil accumulation: A. In oil sands saturated with salt water; B. In oil sands partly saturated; C. In sands containing no water and only partly filled with oil. BROWN COUNTY 43 ent formation are in many cases quite irregular. The oscillations oc-curred without much deformation, however, so that each new series ofbeds was laid down nearly parallel to the beds below. This makes itsafe to assume that anticlines existing in rocks at the surface also existin any oil sands which may occur at some depth. Relation of Structure to Accumulation of OilWhere oil occurs in the rocks there are three principal factorswhich govern its accumulation into pools. These factors are: the exist-ence of a porous reservoir, the presence of impervious rocks above andbelow the porous reservoir, and the favorable rock structure. There areother factors which may apply in certain cases, but in the area underconsideration the three enumerated are believed to be the most

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