<

AMOCO M.G. EISCHEID #1 DEEP PETROLEUM TEST CARROLL COUNTY, IOWA: PRELIMINARY INVESTIGATIONS R.R. Anderson (editor) Iowa Department of Natural Resources, Geological Survey Bureau, Special Report Series No. 2, 1990, 185 p. Preface The Amoco M.G. Eischeid #1 deep petroleum test well, with a total depth of 17,851 feet, is one of the most important drill holes ever to penetrate the rocks of the Midcontinent Rift System (MRS). Drilled in 1987, it penetrated the thickest section of MRS clastic rocks encountered by drilling anywhere along the structure, and it provides an excellent opportunity to compare MRS rocks from the deep Iowa subsurface with related units exposed hundreds of miles to the north in the Lake Superior area. It also affords an excellent opportunity to evaluate the petroleum potential of these ancient rocks in Iowa. Eischeid Report In 1990, the Geological Survey Bureau published Special Report No. 2, The Amoco M.G. Eischeid #1 Deep Petroleum Test, Carroll County, Iowa; Preliminary Investigations, edited by R.R. Anderson. This volume presents the results of initial investigations of rock samples and other data released by Amoco to the Iowa Department of Natural Resources Geological Survey Bureau (GSB). These studies were primarily directed toward investigating the stratigraphy and petrology of the rock units encountered during the drilling, and various factors relating to the petroleum potential of the Proterozoic section. The authors who volunteered to investigate these rocks were required to complete their studies in a very short time in order to make this volume available as soon as possible following the release of the data from confidential status. Although these studies are complete and provide a wealth of information, they are considered preliminary by most researchers, since follow-up studies will probably refine the data and interpretations presented. Core and cutting samples from the M.G. Eischeid #1 well are reposited at the GSB research facility near Iowa City and are available for additional research projects. The first two papers in the volume, by Anderson, describe the Precambrian geological setting of the MRS in Iowa and the structure of the rift as interpreted from geophysical data. A paper by Witzke describes the stratigraphy of the strata encountered during the drilling. McKay discusses the problems of identifying the contact of the basal Cambrian Mt. Simon Sandstone with the underlying MRS clastic rocks. His article was a late addition to the volume, and some reports were completed prior to his identification of basal Mt. Simon contact. Initial stratigraphic picks had indicated that the base of the Mt. Simon Sandstone was much deeper than McKay placed it. Consequently, some papers report a deeper-lying top or a thinner total thickness for the "Red Clastic" strata. Van Schmus and others describe the gabbro encountered at the crystalline surface in the Eischeid well and its age and affinity. Ludvigson and others and Barnes present the results of their petrographic studies of the Eischeid cutting and core samples. The petroleum source-rock potential of the "Red Clastic" rocks is investigated by Palacas and others, their porosity is discussed by Schmoker and Palacas, and Pollastro and Finn report on the clay mineralogy and bulk rock composition of selected intervals of the strata. Ludvigson and Spry discuss the tectonic and paleohydrologic significance of carbonate veinlets in the "Red Clastics" and Barker reports on his study of their fluid inclusions. Finally, Anderson reviews and summarizes the reports that comprise the volume. For more information contact: Ray Anderson phone: (319) 335-1575 e-mail: Raymond.Anderson@dnr.iowa.gov