The Gothic Shale of the Pennsylvanian Paradox Formation, Greater Aneth Field (Aneth Unit), Southeastern Utah: Seal for Hydrocarbons and Carbon Dioxide

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The Gothic Shale of the Pennsylvanian Paradox Formation, Greater Aneth Field (Aneth Unit), Southeastern Utah: Seal for Hydrocarbons and Carbon Dioxide
By: Jason E. Heath, Thomas A. Dewers, Thomas C. Chidsey, Jr., Stephanie M. Carney, and S. Robert Bereskin

Greater Aneth oil field, Utah’s largest oil producer, has produced over 483 million barrels of oil. Located in the Paradox Basin of southeastern Utah, Greater Aneth is a stratigraphic trap producing from the Pennsylvanian Paradox Formation. Because Greater Aneth is a mature, major oil field in the western U.S., and has a large carbonate reservoir, it was selected to demonstrate combined enhanced oil recovery and carbon dioxide (CO2) storage. The Gothic shale seals the underlying Desert Creek oil reservoir, both in the Paradox Formation. Within the Aneth Unit in the northwestern part of the field, the Gothic is remarkably uniform, consisting of 7 to 26 feet (2–8 m) of black to gray, laminated to thin-bedded, dolomitic marine shale.

This 31-page Miscellaneous Publication is a detailed evaluation of the Gothic seal in the Aneth Unit and its effectiveness at supporting large CO2 and hydrocarbon columns in the Desert Creek reservoir below. This study includes geochemical, petrological, petrophysical, and geomechanical analyses that determined (1) the geologic controls on sealing effeciency, (2) effects of pressure changes on the seal due to CO2 injection and storage, and (3) possible chemical interaction between CO2 and the seal at its contact with the reservoir through time.

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Find articles on the Tooele 30’x 60′ quadrangle geologic map and practical uses of geologic maps, along with our regular featured columns.

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Holocene Surface-Faulting Earthquakes at the Spring Lake and North Creek Sites on the Wasatch Fault Zone: Evidence for Complex rupture of the Nephi Segment

Holocene Surface-Faulting Earthquakes at the Spring Lake and North Creek Sites on the Wasatch Fault Zone: Evidence for Complex rupture of the Nephi Segment

By: Christopher B. DuRoss, Michael D. Hylland, Adam I. Hiscock, Stephen F. Personius, Richard W. Briggs, Ryan D. Gold, Gregg S. Beukelman, Greg N. McDonald, Ben A. Erickson, Adam P. McKean, Stephen J. Angster, Roselyn King, Anthony J. Crone, and Shannon A. Mahan

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This 44-page report presents new data from the Spring Lake and North Creek trench sites on the Nephi segment of the Wasatch fault zone. We use paleoseismic data from these sites to refine Holocene earthquake chronologies for the northern and southern strands of the segment, calculate earthquake recurrence and fault slip rates, and assess whether the strands rupture independently or synchronously in large earthquakes. At the Spring Lake site, at least five to seven earthquakes occurred since ~13.1 ka, yielding a mean Holocene recurrence of ~1.2–1.5 kyr; at the North Creek site, at least five earthquakes occurred since ~4.7 ka, yielding a mean recurrence ~1.1–1.3 kyr. We integrate these results with previous paleoseismic data for the segment, discuss the timing and recurrence of large Nephi segment earthquakes, and evaluate possible models of surface-fault rupture involving the two fault strands.

Water Salinity Study for the Southern San Pitch Drainage System in Sanpete County, Utah

Water Salinity Study for the Southern San Pitch Drainage System in Sanpete County, Utah
By: Janae Wallace, J. Lucy Jordan, Christian Hardwick, and Hugh Hurlow

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This project determines the sources and extent of salinity in the lower San Pitch River drainage and adjoining Gunnison Irrigation Company canal system in southern Sanpete Valley using data we acquired over two field seasons documenting water quality and quantity along different reaches within the San Pitch River and Twelvemile Creek as well as nearby canals and springs. We use geologic mapping and geophysical techniques (TEM) to isolate and identify regions in the subsurface that likely have an influence on river salinity. The data collected for this study provide information necessary to make targeted management decisions to reduce salinity and provide for a sustainable supply of acceptable/suitable quality irrigation water for the GIC and its water users. Overall, our maps emphasize areas of higher and lower salinity sources and show calculated salt load to the San Pitch River.

Spring Inventory and Preliminary Groundwater Dependent Ecosystems Assesment of Manti-La Sal National Forest, Wasatch Plateau, Utah

Spring Inventory and Preliminary Groundwater Dependent Ecosystems Assesment of Manti-La Sal National Forest, Wasatch Plateau, Utah
By Paul Inkenbrandt, Richard Emerson, Janae Wallace, J. Lucy Jordan, and Stefan Kirby

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In cooperation with the U.S. Forest Service, the Utah Geological Survey mapped springs and groundwater dependent ecosystems on the Wasatch Plateau. Using remote sensing, GIS, and field checking, more than 400 points were compiled and plotted for use by the Forest Service.

Potential Oil-Prone Areas in the Cane Creek Shale Play, Paradox Basin, Utah, Identified by Epifluorescence Microscope Techniques

Potential Oil-Prone Areas in the Cane Creek Shale Play, Paradox Basin, Utah, Identified by Epifluorescence Microscope Techniques

By: Thomas C. Chidsey, Jr., David E. Eby

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The Cane Creek shale of the Pennsylvanian Paradox Formation has produced more than 7.8 million barrels of oil and about 7.9 billion cubic feet of gas from 18 fields in the Paradox Basin of southeastern Utah. The Cane Creek is divided into three intervals—A, B, and C; the B interval is the primary oil producer. Finely crystalline dolomites and sandstones in the B interval have been the main targets of successful horizontal drilling programs. Hydrocarbon shows were recognized using nondestructive epifluorescence (EF) microscope techniques on samples from wells in the northern part of the basin. A new, qualitative visual EF rating system was developed and applied to these samples. A variety of EF ratings from each well were plotted and mapped.

This 44-page Special Study provides (1) a summary of the new EF methods used in the study; (2) detailed petrographic and EF descriptions of Cane Creek samples for 31 wells (in three appendices); (3) 16 maps showing potential oil-prone areas for the entire Cane Creek and the A, B, and C intervals; and (4) a statistical analysis of the EF data. The study will help petroleum companies determine exploration strategies and land acquisition areas. It will also be a reference for government land management agencies, county planners, and local landowners in decision making processes and resource assessments.

Hydrogeology of the Malad–Lower Bear River Basin, North-Central Utah and South-Central Idaho

Hydrogeology of the Malad–Lower Bear River Basin, North-Central Utah and South-Central Idaho
By: Hugh Hurlow

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This report characterizes the lithology of the younger (i.e., Quaternary) basin fill of the Malad–Lower Bear River basin in north-central Utah to provide a geologic framework for evaluation of groundwater flow and the potential effects of additional future groundwater pumping. Analysis of well-drillers’ logs yielded a coherent lithologic stratigraphy below the valley floor, that consists of alternating predominantly fine-grained and predominantly coarse-grained layers above the Tertiary Salt Lake Formation. These units grade abruptly across a facies transition to heterogeneous, predominantly coarse-grained deposits below the mountain fronts. The valley-floor lithologic succession is consistent with findings from previous studies in Cache Valley and basins along the Wasatch front, and with established Quaternary lake cycles. Three fine-grained layers separated by two gravel layers compose a heterogeneous, composite confining unit below the youngest surficial deposits. Heterogeneous, predominantly coarse-grained deposits between the confining unit and the Salt Lake Formation make up the deep sand and gravel aquifer. Groundwater pumping from the shallow sand and gravel aquifer would cause rapid and direct depletion of stream flow in the Bear River and Malad River, which traverse the basin. Depletion of stream flow and spring flow due to pumping from the deep sand and gravel aquifer would be delayed and dispersed, but not negated, by the composite confining unit.

Major Oil Plays in Utah and Vicinity

Major Oil Plays in Utah and Vicinity

By: Thomas C. Chidsey, Jr., Compiler and Editor

One of the benefits of Utah’s diverse geology is a wealth of petroleum resources. Three oil-producing provinces exist in Utah and adjacent parts of Wyoming, Colorado, and Arizona—the thrust belt, Paradox Basin, and Uinta Basin. Utah produces oil from eight major “plays” within these provinces. This 293-page bulletin describes concisely and in new detail each of these major oil plays. It provides “stand alone” play portfolios which include the following descriptions: (1) tectonic setting; (2) reservoir stratigraphy, thickness, and lithology; (3) type of oil traps; (4) rock properties; (5) oil and gas chemical and physical characteristics; (6) seal and source rocks including timing of generation and migration of oil; (7) exploration and production history; (8) case-study oil field evaluations; (9) reservoir outcrop analogs; (10) exploration potential and trends; and (11) maps of play and subplay areas. The bulletin will help petroleum companies determine exploration, land-acquisition, and field-development strategies; pipeline companies plan future facilities and pipeline routes; and assist with decisions and evaluations faced by landowners, bankers and investors, economists, utility companies, county planners, and numerous government resource management agencies.

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The latest issue of Survey Notes is here!

Our latest issue of Survey Notes is here! Find articles on mapping Utah wetlands & UGS’s role in contributing water-quality data to the National Ground-Water Monitoring Network, and more among our regular featured columns.

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The 2017 Calendar of Utah Geology is here!

The Utah Geological Survey 2017 Calendar of Utah Geology has arrived! The calendars are on sale for $4.95 each or $4.25 for orders of 10 or more at the Utah Natural Resources Map & Bookstore, 1594 West North Temple in Salt Lake City.

The photos are taken by staff members who are often on assignment in some of the most intriguing areas of the state.