Biological Markers in Paleozoic Sedimentary Rocks and Crude Oils from the Michigan Basin: Reassessment of Sources and Thermal History of Organic Matter

Abstract

Paleozoic sedimentary rocks fill the Michigan Basin and provide the sources of the oils produced from this basin. The present geothermal gradient is not high in this shallow sequence, raising questions as to whether Devonian and younger strata are sufficiently thermally mature to have sourced petroleum. The thermal maturities of rock samples from Late Cambrian to Pennsylvanian strata have been determined using the kinetics of apparent transformations of biomarker molecules as an index, augmented by vitrinite reflectance measurements and Rock-Eval pyrolysis data. From the extents of sterane isomerization and the degrees of steroid aromatization in biomarkers extracted from these samples, the geothermal history of the Michigan Basin has been reconstructed. Organic matter in Devonian strata from the center of the basin is thermally mature; it is overmature in Ordovician rocks. The geological history of this basin has evidently been more complex than generally thought, suggesting higher temperatures or lower conduction rates in the past.

Fracture‐fill calcite as a record of microbial methanogenesis and fluid migration: a case study from the Devonian Antrim Shale, Michigan Basin

“…The first is related to the glacial history of the Great Lakes area. The second factor is the relatively immature condition of the abundant organic matter available within the reservoir itself (Rullkötter et al . 1992).…”

“…The first is related to the glacial history of the Great Lakes area. The second factor is the relatively immature condition of the abundant organic matter available within the reservoir itself (Rullkötter et al 1992). On the margins of the Michigan Basin, the Devonian section was never deeply buried, precluding thermal maturation of the organic rich black shales of the Antrim Shale.…”

“…The Lachine has a maximum thickness of 30 m in the NPT, and thins westward to 12 m along the shore of Grand Traverse Bay. Like the Norwood Member, the Lachine Member has high silica and organic matter with low thermal maturity (Table 2; R o = 0.4–0.6; Matthews 1993; Rullkötter et al . 1992).…”

Assessing compositional variability and migration of natural gas in the Antrim Shale in the Michigan Basin using noble gas geochemistry

“…In our study, a greater formation temperature for 594 thermogenic gas (> 250 °C) is suggested, Even with this very high assumed temperature, their 595 mixing model still suggests > 25% thermogenic gases in the Antrim Shale. Thermal maturity of 596 the Antrim Shale in the study area is relatively low and does not support in-situ production of 597 thermogenic methane(Rullkötter et al, 1992), although the TOC content of the Antrim Shale is 598 up to 24%(Martini et al, 1998). Therefore, thermogenic methane, as the major component of the 599 total produced methane in the Antrim within the study area (NPT), must have an external origin.…”

“…These members 144 include the Norwood, Paxton, Lachine, and Upper Antrim (Gutschick and Sandberg, 1991), of 145 which the Norwood and Lachine members have the highest organic content (0.5-24 wt% TOC) 146 and are the main targets of gas exploitation (Martini et al, 1998;Walter et al, 1996). The thermal 147 maturity of the Antrim Shale in the NPT of the Michigan Basin was determined by vitrinite 148 reflectance (R o ) and ranges from 0.4 to 0.6% (Rullkötter et al, 1992), indicating a low level of 149 thermal maturation (preoil generation) (Waples, 1985). 150…”