Petrology and reservoir potential of Tertiary and Mesozoic sandstones, Cook Inlet, Alaska: A preliminary analysis of outcrop samples collected during 2007-2010 field seasons

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Frequently anticipated questions:

What does this data set describe?

Title:
Petrology and reservoir potential of Tertiary and Mesozoic sandstones, Cook Inlet, Alaska: A preliminary analysis of outcrop samples collected during 2007-2010 field seasons
Abstract:
The State of Alaska Division of Geological & Geophysical Surveys (DGGS) and Division of Oil & Gas (DOG) are currently engaged in a multi-year study of the hydrocarbon potential of the Tertiary and Mesozoic strata in Cook Inlet basin. Modal analyses and routine core analyses were performed on Tertiary and Mesozoic siltstones and sandstones collected during the 2007-2010 field seasons from six geographic areas in upper and lower Cook Inlet. The reservoir quality of Cook Inlet sandstones varies widely depending on their mineralogy, geologic age, burial depth, and depositional environment. Tuxedni and Naknek sandstones have poor reservoir quality and are likely to be of equally poor quality down dip. West Foreland sandstones examined have poor reservoir quality and are negatively influenced by their immature volcanic mineralogy. The Hemlock and Tyonek sandstones have good to excellent reservoir quality, largely resulting from their quartzose-feldspathic mineralogy that is physically and chemically stable and burial depths generally less than 3,000 m. It should be emphasized that our observations are based on a limited number of outcrop samples collected from widely dispersed localities.
Supplemental_Information:
The DGGS metadata standard extends the FGDC standard to include elements that are required to facilitate our internal data management. These elements, referred to as "layers," group and describe files that have intrinsic logical or topological relationships. Attribute information for the layers (entity) is included in this metadata file under the "Entity_and_Attribute_Information" section. The layers are titled: >sample-location-details: A CSV file with sample location details, map and sample reference numbers, geographic location, latitude, longitude, and formation assignment. >raw-and-summary-data: An XLSX workbook providing raw and summary data. The spreadsheet is organized into the following tabbed worksheets: Table 2. Raw petrographic data in original format provided by Michael D. Wilson, Table 3. Raw petrographic data converted to format of Decker-Helmold, Table 4. Summary of petrographic data, Table 5. Grain size data in phi units, Table 6. Routine core analysis conducted by Weatherford Labs, Inc.
  1. How should this data set be cited?

    Helmold, K.P., LePain, D.L., Wilson, M.D., and Peterson, C.S., 2013, Petrology and reservoir potential of Tertiary and Mesozoic sandstones, Cook Inlet, Alaska: A preliminary analysis of outcrop samples collected during 2007-2010 field seasons: Preliminary Interpretive Report PIR 2013-5, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 34 p.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -153.41707
    East_Bounding_Coordinate: -150.90787
    North_Bounding_Coordinate: 61.3868
    South_Bounding_Coordinate: 59.61781

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 2007
    Ending_Date: 2010
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: document, digital data download

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a point data set.

    2. What coordinate system is used to represent geographic features?

      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is North American Datum of 1927.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.9786982.

  7. How does the data set describe geographic features?

    pir2013-5-sample-location-details.csv
    A CSV file with sample location details, map and sample reference numbers, geographic location, latitude, longitude, and formation assignment. (Source: Alaska Division of Geological & Geophysical Surveys)

    DGGS_SAMPLE
    Label assigned in the field to identify the sample. (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Follows DGGS convention 20YYAAA9999X: YY=last two digits of year, AAA=geologist initials (one to three characters), 9999=unique station number, X=unique alpha character designating a sample was taken at the field station. Geologists' initials represent the following: DL = Dave LePain, JRM = Jacob Mongrain, BG = Bob Gillis, MAW = Marwan Wartes.

    REFERENCE_NUMBER
    Numeric label assigned to identify the sample throughout this publication. (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Range of values
    Minimum:1
    Maximum:217
    Units:Not applicable

    GENERAL_LOCATION
    General location from which the sample was collected. (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Samples were collected from outcrops and measured sections in the Kenai Peninsula from Homer northward to Clam Gulch, the west side of Cook Inlet from Lewis River westward to Straight Creek, and in lower Cook Inlet along the shores of Tuxedni Bay and the Iniskin Peninsula. See manuscript for sample location maps.

    SPECIFIC_LOCATION
    Specific location from which the sample was collected. These values include nicknames which reflect the actual usage of the geologists who worked on the outcrops and collected the samples. (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Samples were collected from outcrops and measured sections in the Kenai Peninsula from Homer northward to Clam Gulch, the west side of Cook Inlet from Lewis River westward to Straight Creek, and in lower Cook Inlet along the shores of Tuxedni Bay and the Iniskin Peninsula. See manuscript for sample location maps.

    LATITUDE
    Latitude, NAD27 (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Range of values
    Minimum:59.61781
    Maximum:61.3868
    Units:decimal degrees

    LONGITUDE
    Longitude, NAD27 (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Range of values
    Minimum:-153.41707
    Maximum:-150.90787
    Units:decimal degrees

    UNIT
    Geologic unit assignment for each sample. (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Formal codeset
    Codeset Name:Proposed stratigraphic nomenclature for Kenai Group, Cook Inlet
    Codeset Source:Geologic unit assignments were based on previously published maps and ongoing DGGS/DOG fieldwork in the area, primarily Curry and others (1990), Swenson (2003), Little and Naeser (1989), Plafker and others (1989), and Nokleberg and others (1994). See manuscript for a complete reference list and discussion of geologic unit assignments.

    AGE
    Age of the geologic unit. (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    Formal codeset
    Codeset Name:This report
    Codeset Source:The age values of the geologic units were derived from previously published sources. See manuscript for a complete reference list.

    COMMENTS
    Additional descriptive details about the stratigraphic location of the sample. (Source: Alaska Division of Geological & Geophysical Surveys and the Alaska Division of Oil & Gas)

    ValueDefinition
    null or blankNull or blank values indicate that additional descriptive details were not provided by the geologist who collected the sample.

    Interpretations are based on previously published maps and ongoing DGGS/DOG fieldwork in the area. See manuscript for a complete reference list.

    pir2013-5-raw-and-summary-data.csv
    An XLSX workbook providing raw and summary data. The spreadsheet is organized into the following tabbed worksheets: Table 2. Raw petrographic data in original format provided by Michael D. Wilson, Table 3. Raw petrographic data converted to format of Decker-Helmold, Table 4. Summary of petrographic data, Table 5. Grain size data in phi units, Table 6. Routine core analysis conducted by Weatherford Labs, Inc. (Source: Alaska Division of Geological & Geophysical Surveys)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    The samples analyzed in this report were collected over four field seasons by many geologists from several agencies, often working in remote settings. Their assistance is gratefully acknowledged. They include Rick Stanley (U.S. Geological Survey); Marwan Wartes, Bob Gillis, Trystan Herriott, Dave Mauel (Alaska Division of Geological & Geophysical Surveys); Paul Decker, Laura Gregersen, Diane Shellenbaum, Meg Kremer (Alaska Division of Oil and Gas); Paul McCarthy, Jake Mongrain, Keane Richards (University of Alaska Fairbanks). We thank William R. Dickinson for discussions on interpreting tectonic settings from sandstone detrital modes. The manuscript benefited greatly from the review of Bob Gillis, although the authors take sole responsibility for its content. Special thanks go to Merlin 'Spanky' Handley of Pathfinder Aviation for his professionalism, affable demeanor, and skill in shepherding us in the field.

  3. To whom should users address questions about the data?

    Alaska Division of Geological & Geophysical Surveys
    Attn: James Weakland
    GIS Analyst
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907)451-5029 (voice)
    dggsgis@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays

Why was the data set created?

The State of Alaska Division of Geological & Geophysical Surveys (DGGS) and Division of Oil & Gas (DOG) are currently engaged in a multi-year study of the hydrocarbon potential of the Tertiary and Mesozoic strata in Cook Inlet basin. This report presents petrographic and routine core-analysis data and provides preliminary interpretations of rock samples. The samples were collected from Tertiary sections on the Kenai Peninsula from Homer northward to Clam Gulch, Tertiary sections on the west side of Cook Inlet from Lewis River westward to Straight Creek, and sections of Mesozoic strata in lower Cook Inlet along the shores of Tuxedni Bay and the Iniskin Peninsula.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 2007 (process 1 of 4)
    Sample collection and geologic formation assignment - Tertiary and Mesozoic siltstones and sandstones from six geographic areas in the upper and lower Cook Inlet were collected during the 2007-2010 field seasons. Initial formation assignment for each sample was based on previously published maps and ongoing DGGS/DOG fieldwork in the area. In some cases assignments were modified after the modal data were analyzed to ensure petrographically similar samples were included in the same unit. After much experimentation a procedure was developed to acquire usable samples that could be plugged for analysis. This entailed excavating large "bread-loaf" sized samples that were immediately wrapped in several layers of plastic wrap and secured in canvas bags with duct tape. These samples were later placed in plastic bags and covered with a thin coating of epoxy resin prior to shipping.

    Date: 2011 (process 2 of 4)
    Modal analysis - Samples were submitted to Michael D. Wilson, a geological consultant in Lakewood, CO, for modal analysis. He counted a minimum of 300 grains via the traditional point-counting method (Decker and Helmold, 1985) to determine the composition of the framework (detrital grains) and intergranular components (matrix, cement, porosity). A second count of 200 grains (including matrix) was conducted for grain size.

    Date: 2011 (process 3 of 4)
    Routine core analysis - Samples were submitted to Weatherford Labs, Inc. for routine core analysis to determine porosity and permeability.

    Date: 2011 (process 4 of 4)
    Data interpretation - Modal analysis and porosity and permeability datasets were plotted and examined to provide a preliminary interpretation of the petrology and reservoir potential of the rock units. See manuscript for more information about the interpretive process and results. The manuscript also provides a detailed list of pertinent references.

  3. What similar or related data should the user be aware of?

    Blodgett, R.B., 2009, Report on day trip (5/16/07) to visit Mesozoic rocks exposed in Port Graham and near Seldovia, southern Kenai Peninsula: Preliminary Interpretive Report PIR 2009-8C, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: p. 109-116
    Finzel, E.S., Gillis, R.J., Ridgway, K.D., and LePain, D.L., 2009, Preliminary evaluation of basin margin exhumation and provenance of Cenozoic strata, Chuitna and Beluga rivers area, Cook Inlet forearc basin, Alaska: Preliminary Interpretive Report PIR 2009-4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 16 p
    Finzel, E.S., Ridgway, K.D., and LePain, D.L., 2009, Sedimentology of an Oligocene-Miocene incised paleovalley, Tyonek Formation, Cook Inlet Basin, Alaska: Preliminary Interpretive Report PIR 2009-8B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: p. 99-107
    Gillis, R.J., LePain, D.L., Ridgway, K.D., and Finzel, E.S., 2009, A reconnaissance view of an unnamed fault near Capps Glacier, northwestern Cook Inlet basin, and its potential as a regional-scale, basin-controlling structure: Preliminary Interpretive Report PIR 2009-3, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 9 p
    Hickey, J.J., Wilson, M.D., and Reifenstuhl, R.R., 2007, Petrographic study of 50 samples from the Tertiary sandstone of Cook Inlet, Alaska: potential tight gas reservoirs: Report of Investigation RI 2007-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 64 p
    LePain, D.L., Wartes, M.A., McCarthy, P.J., Stanley, R.G., Silliphant, L.J., Peterson, Shaun, Shellenbaum, D.P., Helmold, K.P., Decker, P.L., Mongrain, Jacob, and Gillis, R.J., 2009, Facies associations, sand body geometry, and depositional systems in Late Oligocene-Pliocene Strata, southern Kenai Peninsula, Cook Inlet, Alaska: Report on progress during the 2006-07 field season: Preliminary Interpretive Report PIR 2009-8A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: p. 1-97
    LePain, D.L., 2009, Preliminary results of recent geologic investigations in the Homer-Kachemak Bay area, Cook Inlet Basin: Progress during the 2006-2007 field season: Preliminary Interpretive Report PIR 2009-8, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 187 p
    Loveland, A.M., 2010, Results of mercury-injection capillary pressure tests on outrcrop samples in the Tyonek area of Cook Inlet: Raw Data File RDF 2010-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 102 p
    Loveland, Andrea, 2009, Mercury injection capillary pressure results from outcrop samples in the Homer area of Cook Inlet: Preliminary Interpretive Report PIR 2009-8D, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: p. 117-187
    Reger, R.D., 2009, Reinterpretation of the Kaloa deposits near Granite Point, northwestern Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2009-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 8 p
    Shellenbaum, D.P., Gregersen, L.S., and Delaney, P.R., 2010, Top Mesozoic unconformity depth map of the Cook Inlet Basin, Alaska: Report of Investigation RI 2010-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:500,000
    Zippi, P.A., and Loveland, A.M., 2012, Palynological analysis of 228 outcrop samples from the Kenai, Seldovia, and Tyonek quadrangles, Cook Inlet region, Alaska: Raw Data File RDF 2012-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 10 p

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    This report has received one technical review by a scientist familiar with the subject matter. We incorporated the reviewer's suggestions into the final draft.

  2. How accurate are the geographic locations?

    Location coordinates were obtained using handheld GPS units with a typical error of 7 m or less.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    The data presented in this report should be viewed as preliminary. It should be emphasized that our observations are based on a limited number of outcrop samples collected from widely dispersed localities. Future data may provide additional insight into the petrology and reservoir potential of Tertiary and Mesozoic sandstones of Cook Inlet, Alaska.

  5. How consistent are the relationships among the observations, including topology?

    Not applicable

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.

  1. Who distributes the data set? (Distributor 1 of 1)

    Alaska Division of Geological & Geophysical Surveys
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (<http://www.dggs.alaska.gov>) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set?

    PIR 2013-5

  3. What legal disclaimers am I supposed to read?

    The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 25-Apr-2013
Metadata author:
Metadata manager
3354 College Road
Fairbanks, AK 99709-3707
USA

(907)451-5020 (voice)

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.21 on Thu Apr 25 10:02:24 2013