Cambrian Mount Simon Sandstone Research Articles

Interpreting pre-vegetation landscape dynamics: The Cambrian Lower Mount Simon Sandstone, Illinois, U.S.A.

ABSTRACTThe Cambrian Mount Simon Sandstone has been the subject of extensive study and multiple industrial-scale carbon storage demonstrations at Decatur, Illinois, USA. The development of a reliable paleoenvironmental model is critical to successful large-scale carbon dioxide (CO2) storage, but is complicated by the need to interpret pre-vegetation sedimentation processes. The present study presents a paleoenvironmental model of the Lower Mount Simon Sandstone, based on analysis of primary sedimentary structures in two cores and four complete high-resolution resistivity logs (FMI).The Lower Mount Simon Sandstone represents a vertical “drying-up” sequence composed of three associated depositional units: a north–south oriented coastal system at the base, an eastward-directed fluvial unit in the middle, and a westward-directed eolian system at the top that recycled medium- and fine-grained sand in the basin. Quantitative analysis of fluvial cross-strata indicates that the perennial river system was shallow (c. 1 m deep) with relatively narrow channel belts (c. 1 km). Adjacent sandy eolian-floodplain deposits contain abundant thin, crinkly planar laminae that are enriched in fines and are interpreted as cementation surfaces, likely of biological origin. Deflation lags and wind-ripple strata are commonly interbedded with the crinkly strata, suggesting that the recurrence of erosion and deposition that controlled sedimentary preservation on the floodplain were dominated by eolian transport, re-wetting, and (bio-) cementation. Such a prominent role of exposure to the wind, basin-scale sediment recycling, and eolian removal of fine-grained sediment would have ceased to exist for most climates after the development of vegetation on land, yet, may well be key to understanding the environmental context for early life on Earth.

Grenville Foreland Deformation and Sedimentation in Southwest Ohio Indicated by Reprocessed Seismic Reflection Profiles near Middletown, Ohio, USA

The late Mesoproterozoic to early Neoproterozoic Middle Run Formation contains vital information about the crustal evolution of the North American Craton. Four reprocessed seismic reflection lines in the vicinity of the AK Steel facility in Middletown, Ohio, provide new insights into the structural and depositional setting of the Middle Run Formation in this region. A residual statics solution improved the resolution and coherency of reflections in these profiles that underlie the Cambrian Mount Simon Sandstone. Reprocessing revealed gently inclined, west-southwest-dipping reflectors and the occurrence of an angular unconformity between the Middle Run Formation and the overlying Paleozoic strata. The weak and discontinuous seismic reflection character of the Middle Run Formation in these seismic lines overlies a sequence of stronger parallel reflections that are like those observed on the eastward ODNR-1-88 seismic line located near core hole DGS 2627, the stratotype of the Middle Run Formation. This inferred thickness indicates that the basin in which the Middle Run Formation was deposited ranges from at least 670 to 1,128 m (2,200 to 3,700 ft) deep at the AK Steel area and dips gently west-southwest, which is in contrast with the moderate easterly dip observed on the ODNR-1-88 seismic line to the northeast. Correlation of these features across the 10 km (approximately 6 mi) cross-strike gap between the AK Steel lines and the ODNR-1-88 seismic line suggests the presence of a reverse fault with approximately 792 m (2,600 ft) of estimated vertical displacement. A regional cross section—including the WSU 1990 seismic line eastward of the ODNR-1-88 line—exhibits a faulted west-verging asymmetric syncline in near proximity to the Grenville Front. This cross section also shows that deformation of the Middle Run Formation and the underlying layered sequence exhibits a consistent tectonic style of reverse faulting and folding that developed in response to Grenville Front tectonism.

Anatomy of a Sub-Cambrian Paleosol in Wisconsin: Mass Fluxes of Chemical Weathering and Climatic Conditions in North America during Formation of the Cambrian Great Unconformity

AbstractA paleosol beneath the Upper Cambrian Mount Simon Sandstone in Wisconsin provides an opportunity to evaluate the characteristics of Cambrian weathering in a subtropical climate, having been...

Geomechanical behavior of Cambrian Mount Simon Sandstone reservoir lithofacies, Iowa Shelf, USA

The Mount Simon Sandstone (Mt. Simon), a basal Cambrian sandstone underlying much of Midwestern US, is a target for underground CO2 storage and waste injection which requires an assessment of geomechanical behavior. The range of depositional environments yields a heterogeneous formation with varying porosity, permeability, and mechanical properties. Experimental deformational behavior of three distinct Mt. Simon lithofacies was examined via axisymmetric compressional testing of core samples. Initial yielding was confirmed with acoustic emissions in many tests and failure envelopes were determined for each lithofacies. Evolution of elastic moduli with stress and plastic strain was determined by use of unload–reload cycles, which permit separation of total measured strains into elastic and plastic strains. The Upper Mt. Simon lithofacies yields at higher shear stresses compared to two “Lower” lithofacies, with little modulus degradation with plastic strain. Lower Mt. Simon lithofacies are weaker and deform plastically with modulus degradation. This range in constitutive response is quantified with an elasto-plasticity model. Based on these results, Mount Simon Sandstone would likely deform elastically during CO2 injection and storage, with large pore pressure increases (∼8–9MPa above hydrostatic) predicted to initiate plastic yielding. Nonetheless, near-wellbore damage could result in weaker lithofacies during injection and/or brine extraction.

Modeling CO2–brine–rock interactions in the Knox Group: Implications of a deep carbon storage field test in western Kentucky

The Cambrian–Ordovician Knox Group, a thick sequence of dolostone and minor dolomitic sandstone, is a prospective CO2 sequestration target in the southern Illinois Basin, USA. Thorough evaluation of the Knox Group is critical because the main sequestration target elsewhere in the Illinois Basin, the Cambrian Mount Simon Sandstone, is thin or absent throughout most of Kentucky. A 2477-m-deep carbon storage test well in Hancock County, Kentucky, was drilled, and 626metric tons of CO2 was injected into the Knox saline reservoirs. To understand the long-term fate of CO2 injected into the Knox reservoirs, geochemical reactions between CO2, brine and rock-forming minerals were modeled using TOUGHREACT. The modeling benefited from a robust data set collected from the test well, including core porosity and permeability, petrographic and X-ray powder diffraction mineralogy, brine chemistry, temperature and pressure measurements. Kinetic batch models and 2-D radial reactive transport models were used to evaluate the migration of the injected CO2, changes in brine chemistry, and mineral dissolution and precipitation. Results from the kinetic models suggest that sections of the Knox dominated by dolomite have very limited mineral-trapping capacity for CO2, whereas thin sections of dolomitic sandstone with aluminosilicate minerals such as K-feldspar facilitate mineral trapping. The 2-D model for the CO2 injection test suggests that, because of the presence of thick permeable intervals in the Knox and the small volume of injected CO2 in the test, the radius of influence is less than 11m from the well. The hypothetical long-term injection model indicates, on the other hand, that commercial-scale injection would influence a much larger area and part of the injected CO2 remains in the supercritical/gas phase for a long time. Because of the buoyancy effect, most supercritical/gas-phase CO2 migrates upward and stays in the top of the reservoirs dominated by dolomite with small mineral-trapping capacity.

Fluctuations in Sedimentary Provenance of the Upper Cambrian Mount Simon Sandstone, Illinois Basin, United States

Abstract Understanding sedimentary provenance is essential when investigating clastic strata. The lack of compositional variability in mature sediments associated with Cambrian cratonic sequences in the United States makes traditional petrographic discrimination of sedimentary origin difficult. The upper Cambrian Mount Simon Sandstone of the Illinois Basin is a quartz arenite (Q93F5L2 and Qm85F5Lt10) with unconstrained sediment provenance and is also the reservoir for ongoing injection of a million tons of CO2. This study investigates whether fluctuations in sedimentary provenance caused changes in the composition and texture of the Mount Simon Sandstone reservoir through its deposition. Core descriptions, petrographic analyses of 35 thin sections, and LA-ICPMS analyses of five detrital zircon samples, collected from 878 feet of the Mount Simon Sandstone depositional interval in Stephenson County, Illinois, the only known core that includes the entire formation, yield new compositional data and U-Pb ages....

Lithologic, mineralogical, and petrophysical characteristics of the Eau Claire Formation: Complexities of a carbon storage system seal

Concerns about potential climate change related to greenhouse gas emissions have spurred researchers across the world to assess the viability of geologic storage of CO2. In the Illinois Basin in the United States, the Cambrian Mount Simon Sandstone has been targeted as a reservoir for carbon capture and storage (CCS). In this CCS system, the Eau Claire Formation is expected to serve as the primary seal to prevent upward migration of the CO2 plume; however, little work has been done to specifically determine how well it will function as a seal. Although the lateral extent and thickness of the Eau Claire Formation, along with its generally low permeability, certainly make it a prime candidate to serve in this capacity, the primary depositional fabric and mineralogy, which are the fundamental controls on the petrophysical charter of this unit, remain poorly constrained. Therefore, the purpose of this study is to investigate the lithologic, mineralogical, and petrophysical properties of the Eau Claire Formation in an effort to characterize its potential as a functional seal in a CCS system. Sixty-six core-derived Eau Claire Formation samples from seven wells within the Illinois Basin are described using a combination of petrography, reflectance spectroscopy, x-ray diffraction, geochemical, and petrophysical analyses. These analyses show that the Eau Claire Formation contains five different lithofacies (sandstone, clean siltstone, muddy siltstone, silty mudstone, and shale) with fine-scale heterogeneities in fabric and mineralogy that greatly influence the petrophysical properties. Porosity, permeability, and entry-pressure data suggest that some, but not all, lithofacies within the Eau Claire Formation have the capability to serve as a suitable CCS seal. Abundant authigenic minerals and dissolution textures indicate that multiple generations of past fluid-rock interactions have occurred within the Eau Claire Formation, demonstrating that much of the formation has behaved as a fluid conduit instead of as a seal. Minerals that would be potentially reactive in a CCS system (including carbonate, glauconite, and chlorite) are common in the Eau Claire Formation. Dissolution of these and other phases in the presence of carbonic acid could potentially jeopardize the sealing integrity of the unit. Although complexities in the sealing properties exist, the dynamics of the CCS system and the potential for precipitation of new minerals should allow the Eau Claire Formation to serve as an adequate seal.

Characterizing Fractures and Deformation Bands: Implications for Long-Term CO2 Storage within the Cambrian Mount Simon Sandstone

Multiple approaches are under development to mitigate the release of potentially harmful human-generated CO2 into the atmosphere. Geologic carbon sequestration is one such process by which CO2 that would otherwise be vented to the atmosphere is liquefied, injected, and stored in the pore space of a subsurface reservoir. The Cambrian Mount Simon Sandstone (MSs) is a targeted reservoir for CO2 sequestration in the Illinois Basin. The goals of this research are to analyze a set of subsurface samples related to ongoing CO2 sequestration demonstrations in the Illinois Basin. These samples contain evidence of small-scale fractures and deformation bands in the MSs. We provide a detailed analysis of their geometry, association with sedimentary facies, potential origin, and any apparent fluid-related diagenesis. Core samples displaying fractures were analyzed visually to characterize the sandstone and fracture geometry, and at higher resolution using thin section transmitted light petrography. Scanning electron microscopy with energy dispersive X-ray analysis (SEMEDX) was used to analyze even smaller-scale structures along with select geochemical properties. Observed fracture types in the MSs include: 1) deformation bands and 2) open fractures filled with authigenic cements. Observed deformation band types include a) compaction bands, b) shear bands, and c) cemented dilatation bands. Low porosity/permeability deformation bands have the potential to block fluid migration, while open fractures create secondary porosity/permeability. These small-scale deformational structures can impact the routes that migrating fluids will travel along, therefore directly impacting CO2 sequestration operations.

Evolution of quartz cementation during burial of the Cambrian Mount Simon Sandstone, Illinois Basin: In situ microanalysis of δ18O

The thermal, mechanical, and chemical evolution of a sedimentary basin exerts important controls on porosity and permeability of reservoir rocks. Oxygen isotope ratios of individual diagenetic cements record evidence of this history, but cannot be analyzed accurately by conventional techniques. Recent improvements for in situ analysis by ion microprobe provide high precision and accuracy at a scale of 5–10 μm. In combination with cathodoluminescence imaging, in situ analysis of δ 18 O (quartz) from the Cambrian Mount Simon Sandstone in the Illinois Basin (USA) reveals gradients within single overgrowths of as much as 7.7‰/50 μm. While the inner portions of overgrowths remain approximately constant in δ 18 O across the basin, the δ 18 O of the rim becomes lower with depth. These data suggest that overgrowths formed during burial and heating, possibly with minimal changes in δ 18 O of pore fluids. If δ 18 O(H 2 O) = −3‰, the highest temperature calculated for the rim of an overgrowth is 107 °C at a paleodepth of 3.5 km. The variability both in average δ 18 O of overgrowths and patterns from individual overgrowths corresponds with a geotherm of 30 °C/km, and there is no evidence of quartz precipitation from higher temperature hydrothermal fluids.

Depositional and diagenetic variability within the Cambrian Mount Simon Sandstone: Implications for carbon dioxide sequestration

The Cambrian Mount Simon Sandstone is the major target reservoir for ongoing geologic carbon dioxide (CO2) sequestration demonstrations throughout the midwest United States. The potential CO2 reservoir capacity, reactivity, and ultimate fate of injected CO2 depend on textural and compositional properties determined by depositional and diagenetic histories that vary vertically and laterally across the formation. Effective and efficient prediction and use of the available pore space requires detailed knowledge of the depositional and diagenetic textures and mineralogy, how these variables control the petrophysical character of the reservoir, and how they vary spatially. Here, we summarize the reservoir characteristics of the Mount Simon Sandstone based on examination of geophysical logs, cores, cuttings, and analysis of more than 150 thin sections. These samples represent different parts of the formation and depth ranges of more than 9000 ft (2743 m) across the Illinois Basin and surrounding areas. This work demonstrates that overall reservoir quality and, specifically, porosity do not exhibit a simple relationship with depth, but vary both laterally and with depth because of changes in the primary depositional facies, framework composition (i.e., feldspar concentration), and diverse diagenetic modifications. Diagenetic processes that have been significant in modifying the reservoir include formation of iron oxide grain coatings, chemical compaction, feldspar precipitation and dissolution, multiple generations of quartz overgrowth cementation, clay mineral precipitation, and iron oxide cementation. These variables provide important inputs for calculating CO2 capacity potential, modeling reactivity, and are also an important baseline for comparisons after CO2 injection.

Effects of reduction in porosity and permeability with depth on storage capacity and injectivity in deep saline aquifers: A case study from the Mount Simon Sandstone aquifer

The Upper Cambrian Mount Simon Sandstone is recognized as a deep saline reservoir that has significant potential for geological sequestration in the Midwestern region of the United States. Porosity and permeability values collected from core analyses in rocks from this formation and its lateral equivalents in Indiana, Kentucky, Michigan, and Ohio indicate a predictable relationship with depth owing to a reduction in the pore structure due to the effects of compaction and/or cementation, primarily as quartz overgrowths. The regional trend of decreasing porosity with depth is described by the equation: ϕ( d) = 16.36 × e −0.00039* d , where ϕ is the porosity and d is the depth in m. The decrease of porosity with depth generally holds true on a basinwide scale. Bearing in mind local variations in lithologic and petrophysical character within the Mount Simon Sandstone, the source data that were used to predict porosity were utilized to estimate the pore volume available within the reservoir that could potentially serve as storage space for injected CO 2. The potential storage capacity estimated for the Mount Simon Sandstone in the study area, using efficiency factors of 1%, 5%, 10%, and 15%, is 23,680, 118,418, 236,832, and 355,242 million metric tons of CO 2, respectively.

Geological sequestration of carbon dioxide in the Cambrian Mount Simon Sandstone: Regional storage capacity, site characterization, and large-scale injection feasibility, Michigan Basin

The Mount Simon Sandstone (Cambrian) is recognized as an important deep saline reservoir with potential to serve as a target for geological sequestration in the Midwest, United States. The Mount Simon Sandstone in Michigan consists primarily of sandy clastics and grades upward into the more argillaceous Eau Claire Formation, which serves as a regional confining zone. The Mount Simon Sandstone lies at depths from about 914 m (3000 ft) to more than 4572 m (15,000 ft) in the Michigan Basin and ranges in thickness from more than 396 m (1300 ft) to near zero adjacent to basement highs. The Mount Simon Sandstone has variable reservoir quality characteristics dependent on sedimentary facies variations and depth-related diagenesis. On the basis of well-log-derived net porosity from wells in the Michigan Basin, estimates of total geological sequestration capacity were determined to be in excess of 29 billion metric tons (Gt). Most of this capacity is located in the southwestern part of the state. Numerical simulations of carbon dioxide (CO2) injection were conducted using the subsurface transport over multiple phases-water-CO2-salt (STOMP-WCS) simulator code to assess the potential for geologic sequestration into the Mount Simon saline reservoir in the area of Holland, Ottawa County, Michigan. At this locality, the reservoir is more than 260 m (850 ft) thick and has a minimum of 30 m (100 ft) of net porosity. The simulation used a CO2 injection period of 20 yr at a rate of 600,000 metric tons (t)/yr, followed by an equilibration period of 280 yr, for a total of 300 yr. After 20 yr, the total amount of CO2 injected is 12 million metric tons (Mt); after 300 yr, 9.8 Mt is modeled to remain as a free-phase (nonentrapped) supercritical CO2, 0.7 Mt is capillary-entrapped (residual) supercritical CO2, and 1.5 Mt dissolved into the brine. The injected CO2 spread to an area with a radius of 1.8 km (1.12 mi) after 20 yr of injection at a single well and to an area with a radius of 3.8 km (2.36 mi) after 300 yr. The low-permeability Eau Claire retards the upward migration of CO2. Pressures during injection at the bottom of the cap rock (1540.5-m [5054-ft] depth) are well below the fracture pressure limit of 27.9 MPa (4046.6 psi), assuming a fracture pressure gradient of 0.018 MPa/m (0.8 psi/ft) caused by the high permeability of the Mount Simon Sandstone.

Sensitive high resolution ion microprobe (SHRIMP) detrital zircon geochronology provides new evidence for a hidden Neoproterozoic foreland basin to the Grenville Orogen in the eastern Midwest, U.S.A.

A sensitive high resolution ion microprobe (SHRIMP) was used in combination with backscattered electron (BSE) and cathodoluminescence (CL) images to determine the age of detrital zircons from sandstones in the Neoproterozoic Middle Run Formation of the eastern Midwest, United States. Eleven samples from seven drill cores of the upper part of the Middle Run Formation contain detrital zircons ranging in age from 1030 to 1982 Ma (84 analyses), with six distinctive modes at 1.96, 1.63, 1.47, 1.34, 1.15, and 1.08 Ga. This indicates that most, but not all, of the zircon at the top of the Middle Run Formation was derived from the Grenville Orogen. The youngest concordant detrital zircon yields a maximum age of 1048 ± 22 Ma for the Middle Run Formation, indicating that the formation is younger than ca. 1026 Ma minus the added extra time needed for later uplift, denudation, thrusting, erosion, and transport to southwestern Ohio. Thus, as judged by proximity, composition, thickness, and geochronology, it is a North American equivalent to other Neoproterozoic Grenvillian-derived basins, such as the Torridon Group of Scotland and the Palmeiral Formation of South America. An alternate possibility, although much less likely in our opinion, is that it could be much younger, any time between 1048 ± 22 Ma and the deposition of the Middle Cambrian Mount Simon Sandstone at about 510 Ma, and still virtually almost all derived from rocks of the Grenville Orogen.

Regional fluid migration in the Illinois basin: Evidence from in situ oxygen isotope analysis of authigenic K-feldspar and quartz from the Mount Simon Sandstone

Oxygen isotope compositions of widespread, authigenic K-feldspar and quartz overgrowths and cements in the Upper Cambrian Mount Simon Sandstone were measured by ion microprobe in 11 samples distributed across the Illinois basin and its periphery. Average K-feldspar δ 18 O values increase systematically from +14‰ ± 1‰ in the southernmost and deepest samples in Illinois to +24‰ ± 2‰ in the northernmost outcrop sample in Wisconsin. A similar trend was observed for quartz overgrowths (22‰ ± 2‰ to 28‰ ± 2‰). Constant homogenization temperatures (100–130 °C) of fluid inclusions associated with quartz overgrowths throughout the basin suggest that the geographic trend in oxygen isotope compositions is a result of diagenetic modification of a south to north migrating basinal fluid.

Enhanced Gas Storage Reservoir Characterization through Core-Derived Flow Units, Facies and Log Integration of Cambrian Mount Simon Sandstone, Illinois: ABSTRACTS

Enhanced Gas Storage Reservoir Characterization through Core-Derived Flow Units, Facies and Log Integration of Cambrian Mount Simon Sandstone, Illinois: ABSTRACTS

Subsurface Stratigraphy and Structure of Sauk Sequence of Northern Ohio: ABSTRACT

The lower Paleozoic Sauk sequence of northern Ohio represents a carbonate and clastic sedimentary sequence deposited during the late Late End_Page 1440------------------------------ Cambrian Saint Croixan and early Early Ordovician Canadian. It is bounded below by the unconformity on the Precambrian basement and above by the Knox unconformity. The Sauk sequence was deposited throughout the study area of northern Ohio, which includes the western portion of the Appalachian basin, the Ohio-Indiana platform to the west, and the southernmost portion of the Michigan basin northwest of the Ohio-Indiana platform. The major lithostratigraphic units, all in the subsurface, are the Cambrian Mount Simon Sandstone, Shady Dolomite, Eau Clair Formation, Rome Formation, and Kerbel Formation, and the Cambrian-Ordovician Knox Group. Stratigraphic interpretations generally show that the Sauk sequence begins with clastic deposition occurring in the north-central and western portions of Ohio and predominantly carbonate and open-marine clastic deposition occurring in eastern and south-central Ohio. The location of the present Cincinnati arch marks a transition zone between the two sedimentary regimes. The final stage of Sauk sequence deposition was marked by a major marine transgression that resulted in deposition of the Knox Dolomite over the entire study area. Producing reservoirs occur in four stratigraphic-structural settings. The Copper Ridge Dolomite (Knox Group) on the eastern edge of the Ohio-Indiana platform has oil production from glauconitic sandstone reservoirs. Basinward, the Cambrian dolomitic Rose Run Sandstone Member occurs at the top of the Copper Ridge Dolomite. Mainly gas has been discovered in the Rose Run in secondary reservoirs formed during erosion of the Knox unconformity. Middle Ordovician shales and impermeable limestones are the seals. The majority of hydrocarbon production from the Knox Dolomite is located in central Ohio's Morrow County where erosional remnants of vuggy dolomite on the Knox unconformity form paleotopographic highs with Middle Ordovician shale as the seal. Other small pools consist of vuggy dolomite reservoirs with small structural closures. Although no significant amounts of hydrocarbons have been discovered below the Copper Ridge Dolomite, high porosities and permeabilities in the Mount Simon Sandstone and Eau Claire Formation lend potential to these rocks for liquid waste disposal. End_of_Article - Last_Page 1441------------

Rock Elm structure, Pierce County, Wisconsin: A possible cryptoexplosion structure

The Rock Elm structure is a nearly circular feature in western Wisconsin flat 44°43′N, long 92°14′W) in an area of otherwise little-deformed Cambrian and Ordovician shallow-marine sediments. The structure has a ring boundary fault with at least 50 m of vertical displacement, a sediment-filled ring basin, and central denial uplift. The ring basin fill consists of a shale-sandstone sequence of probable Ordovician age not found outside of the structure. Blocks of deformed Lower Ordovicisin carbonates are generally in angular unconformity beneath the basin fill but locally are in fault contact against basin-fill rocks. The central dome consists of conglomeratic sandstones, tentatively identified as the Upper Cambrian Mount Simon Sandstone, that have been uplifted more than 250 m. Although the deformation of the rocks is unusual for the region, there have been no shock-metamorphic features yet found associated with the structure. The Rock Elm structure has the essential features of a cryptoexplosion structure as described by Dietz and by McCall. Conclusive evidence is lacking as to whether the Rock Elm structure formed as a result of a bolide impact, explosive volcanic event, or other localized violent geologic event.