REVIEW OF CURRENT STUDIES OF PROTEROZOIC ROCKS IN THE AMOCO M.G. EISCHEID #1 PETROLEUM TEST WELL, CARROLL COUNTY, IOWA

by
R.R. Anderson

Iowa Department of Natural Resources, Geological Survey Bureau
Special Paper Series No. 2, 1990, p. 175-184
The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa
R.R. Anderson, ed.

ABSTRACT


The M.G. Eischeid #1 petroleum exploration test was drilled in 1987 by the Amoco Production Company to test the hydrocarbon potential of the clastic rocks of the Midcontinent Rift System (MRS) in Carroll County in west-central Iowa. The well reached a total depth of 17,851 feet, far surpassing the 5,305-foot depth of the previous deepest well in the state, and making it one of the deepest in the midcontinent.

The Eischeid well penetrated 2,802 feet of Phanerozoic strata overlying 14,898 feet of Keweenawan Supergroup clastic rocks before encountering a gabbroic crystalline basement at a depth of 17,700 feet. Preliminary investigation of samples of the Keweenawan clastic rocks from the well led to the differentiation by Witzke (1990) of two informal groups and seven informal formations. The lower group is compositionally similar to and probably correlative with the Oronto Group of Wisconsin; the upper group is similar to the Bayfield Group of Wisconsin and was probably deposited in a similar setting.

Amoco Production Company granted permission for Iowa Department of Natural Resources Geological Survey Bureau (GSB) geologists and selected additional researchers to examine cores, cuttings, and logs from the Eischeid well prior to their release from confidential status for the production of this volume. The stratigraphy of all rock units (Phanerozoic and Proterozoic) encountered during the drilling of the Eischeid well were investigated, and the units identified by Witzke (1990). The difficulties in identifying the contact between the lithologically similar Cambrian Mt. Simon Sandstone and the Upper "Red Clastic" Sequence were reviewed, and the rationale for picking the contact in the Eischeid well was discussed by McKay (1990). The petroleum source rock potential of the thick sequences of dark gray to black shales and siltstone encountered in the Lower "Red Clastic" Sequence was investigated (Palacas et al., 1990) as was the porosity of sandstone dominated units above and below the dark, fine-grained rocks (Schmoker and Palacas, 1990). Preliminary petrographic studies (Ludvigson et al., 1990; Barnes, 1990), clay mineralogy investigations (Pollastro et al., 1990), and fluid inclusion studies (Barker, 1990; Ludvigson and Spry, 1990) have provided a basic understanding of the post-depositional history of the Keweenawan clastic units. Finally, the gabbro at the bottom of the Eischeid well was investigated and its age determined by Van Schmus and others (1990).


REFERENCES:

Barker, C.E., 1990, Reconnaissance fluid inclusion study, Amoco Eischeid #1 well, Defiance Basin, Mid-Continent Rift System, Iowa, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 169-173.

Barnes, D.A., 1990, Sandstone petrology from conventional core in the M.G. Eischeid #1 well, Carroll County, Iowa, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 113-118.

Ludvigson, G.A., McKay, R.M., and Anderson, R.R., 1990, Petrology of Keweenawan sedimentary rocks in the M.G. Eischeid #1 drillhole, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 77-111.

Ludvigson, G.A., and Spry, P.G., 1990, Tectonic and paleohydrologic significance of carbonate veinlets in the Keweenawan sedimentary rocks of the Amoco M.G. Eischeid #1 drillhole, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 153-167.

McKay, R.M., 1990, Regional aspects of the Mt. Simon Formation and the placement of the Mt. Simon - pre-Mt. Simon sedimentary contact in the Amoco M.G. Eischeid #1 drillhole, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 59-66.

Palacas, J.G., Schmoker, J.W., Dawes, T.A., Pawlewicz, M.J., and Anderson, R.R., 1990, Petroleum source-rock assessment of Middle Proterozoic (Keweenawan) sedimentary rocks, Eischeid #1 well, Carroll County, Iowa, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 119-134.

Pollastro, R.M., and Finn, T.M., 1990, Clay mineralogy and bulk rock composition of selected core and cutting samples from the Amoco Eischeid #1 well, Carroll County, Iowa -- A reconnaissance study from X-ray powder diffraction analysis, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 143-152.

Schmoker, J.W. and Palacas, J.G., 1990, Porosity of Precambrian sandstones in lower portion of the Eischeid #1 well, Carroll County, Iowa, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 135-142.

Van Schmus, W.R., Wallin, T.E., and Shearer, C.K., 1990, Age relationships for gabbro from the Amoco M.G. Eischeid #1 well, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 67-76.

Witzke, B.J., 1990, General stratigraphy of the Phanerozoic an d Keweenawan sequence, M.G. Eischeid #1 drillhole, Carroll Co., Iowa, in Anderson, R.R., ed., The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa, Preliminary Investigations: Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, p. 39-57.