PCCT measurements of the consolidation characteristics, constrained modulus and compressional wave velocity for fine-grained sediment collected from Area C, Krishna-Godavari Basin during India's National Gas Hydrate Program, NGHP-02

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Title:
PCCT measurements of the consolidation characteristics, constrained modulus and compressional wave velocity for fine-grained sediment collected from Area C, Krishna-Godavari Basin during India's National Gas Hydrate Program, NGHP-02
Abstract:
Understanding how effectively methane can be extracted from a gas hydrate reservoir requires knowing how compressible, permeable, and strong the overlying seal sediment is. This data release provides results for flow-through permeability, consolidation, and direct shear measurements made on fine-grained seal sediment from Site NGHP-02-08 offshore eastern India. The sediment was collected in a pressure core from the Krishna-Godavari Basin during the 2015 Indian National Gas Hydrate Program Expedition 2 (NGHP-02). Gas hydrate is a crystalline solid that forms naturally in the sediment of certain marine and permafrost environments where pressure is relatively high (equivalent to the pressure measured at ~300 meters water depth or more) and temperature is relatively low (but generally above freezing). The concentration of methane can be high enough to make certain gas hydrate occurrences potentially relevant as energy resources. To extract methane from gas hydrate, the in situ formation (generally a coarse-grained, gas-hydrate-bearing sediment interval) can be depressurized by drawing pore water out through a production well. As the pore pressure falls below the gas hydrate stability limit, the solid gas hydrate breaks down, releasing gas and water that migrate toward the production well for collection.
How effectively the production well can depressurize the gas-hydrate-bearing interval depends on how permeable the overlying seal sediment is. If the seal is permeable, depressurizing the reservoir to extract methane causes water to flow out of the seal and into the reservoir. This can limit the ability of the production well to maintain the low reservoir pressure required to break down gas.
Supplemental_Information:
In addition to funding from the U.S. Geological Survey Gas Hydrate Project, this work is sponsored in part by the Department of Energy through an interagency agreement (DE-FE0023495). More information about the project can be found at: https://www.netl.doe.gov/research/oil-and-gas/project-summaries/methane-hydrate/fe0023495-usgs. This work is also part of the NGHP-02 expedition. Links to related data and publications within the NGHP-02 project are collected in the USGS Field Activity Report 2015-023-FA, found at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2015-023-FA.
  1. How might this data set be cited?
    Jang, Junbong, 2018, PCCT measurements of the consolidation characteristics, constrained modulus and compressional wave velocity for fine-grained sediment collected from Area C, Krishna-Godavari Basin during India's National Gas Hydrate Program, NGHP-02: data release DOI:10.5066/P91XJ7DP, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Jang, Junbong, Dai, Sheng, Yoneda, Jun, Waite, William F., Collett, Timothy S., and Kumar, Pushpendra, 2018, Pressure Core Characterization Tool measurements of compressibility, permeability, and shear strength of fine-grained sediment collected from Area C, Krishna-Godavari Basin, during India's National Gas Hydrate Program Expedition NGHP-02: data release DOI:10.5066/P91XJ7DP, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Jang, J., Dai, S., Yoneda, J., Waite, W.F., Collett T.S., and Kumar, P., 2018, Pressure core characterization tool measurements of compressibility, permeability, and shear strength of fine-grained sediment collected from Area C, Krishna-Godavari Basin, during India's National Gas Hydrate Program Expedition NGHP-02: U.S. Geological Survey data release, https://doi.org/10.5066/P91XJ7DP.
    This dataset supports the following publication:
    Jang, J., Dai, S., Yoneda, J., Waite, W.F., Stern, L.A., Boze, L.-G., Collett, T.S., and Kumar, P., 2018. Pressure core analysis of geomechanical and fluid flow properties of seals associated with gas hydrate-bearing reservoirs in the Krishna-Godavari Basin, offshore India: Marine and Petroleum Geology, https://doi.org/10.1016/j.marpetgeo.2018.08.015.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 82.924221
    East_Bounding_Coordinate: 82.924222
    North_Bounding_Coordinate: 16.581168
    South_Bounding_Coordinate: 16.581167
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5b69af1fe4b006a11f774f0b?name=NGHP02_AreaC_Stress_Strain_Modulus_BrowseGraphic.png (PNG)
    PCCT test sequence (arrows) showing permeability and shear strength test conditions during consolidation testing.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 03-Jul-2015
    Currentness_Reference:
    ground condition of the field activity when the original pressure core that was subsampled for this study was collected
  5. What is the general form of this data set?
  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. It contains the following vector data types (SDTS terminology):
      • Point (35)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Meters below sea floor
      Depth_Resolution: 1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    NGHP02_AreaC_Stress_Strain_Modulus_Data
    Stress, void ratio, constrained moduli and compressional wave velocity data for fine-grained NGHP-02 (Krishna-Godavari Basin, offshore India) seal sediment from Site NGHP-02-08 (Source: U.S. Geological Survey)
    Site
    Site: NGHP-02 site name designation. Format is: Expedition Name (NGHP-02)-Site Number and Hole Designation Letter. Hole A was used only for logging-while-drilling (no core recovery). Holes B and C were used for coring. (Source: U.S. Geological Survey) Character set (text).
    J-CORES section ID
    SectionID: Unique, sequential identifier given at the time of collection to any shipboard core section. Cores were collected on the D/V Chikyu, so each ID begins with CKY. (Source: Shipboard science party, D/V Chikyu) Character set (text).
    Latitude (degrees, minutes, seconds)
    Latitude_DMS: Latitude coordinate, in degrees (°) minutes (’) decimal seconds (”), of the sample’s location. North latitude recorded as positive values. Data release describes measurements from a single core, so the location information is single-valued. (Source: Shipboard science party, D/V Chikyu)
    Range of values
    Minimum:16°34'52.206"
    Maximum:16°34'52.206"
    Units:degrees (°) minutes (’) decimal seconds (”)
    Longitude (degrees, minutes, seconds)
    Longitude_DMS: Longitude coordinate, in degrees (°) minutes (’) decimal seconds (”), of the sample’s location. East longitude is recorded as positive values. Data release describes measurements from a single core, so the location information is single-valued. (Source: Shipboard science party, D/V Chikyu)
    Range of values
    Minimum:82°55'27.198"
    Maximum:82°55'27.198"
    Units:degrees (°) minutes (’) decimal seconds (”)
    Latitude (decimal degrees)
    Lat_DD: Latitude coordinate, in decimal-degrees, of sample’s location. North latitude recorded as positive values. (Source: U.S. Geological Survey)
    Range of values
    Minimum:16.58116833
    Maximum:16.58116833
    Units:decimal degrees
    Longitude (decimal degrees)
    Long_DD: Longitude coordinate, in decimal degrees, of the sample’s location. East longitude is recorded as positive values. (Source: U.S. Geological Survey)
    Range of values
    Minimum:82.92422167
    Maximum:82.92422167
    Units:decimal degrees
    Core Subsection
    Subsection: Core NGHP-02-08-30P was cut into several subsections for this test. Each subsection was tested in either the Direct Shear Chamber (DSC) or Effective Stress Chamber (ESC). The section number begins with 1 as the deepest subsection for the core, and increases for subsections taken higher up in the core. (Source: U.S. Geological Survey) Character set (text).
    Top Depth in CSF-B (mbsf)
    CSFB_TopDepth_mbsf: Depth of the top of the subsection in meters below the sea floor (mbsf), using the CSF-B convention in which gas expansion gaps, if present at the time of core recovery, have been removed. (Source: Shipboard science party, D/V Chikyu)
    Range of values
    Minimum:247.12
    Maximum:247.63
    Units:meters
    Bottom Depth in CSF-B (mbsf)
    CSFB_BottomDepth_mbsf: Depth of the bottom of the subsection in meters below the sea floor (mbsf), using the CSF-B convention in which gas expansion gaps, if present at the time of core recovery, have been removed. (Source: Shipboard science party, D/V Chikyu)
    Range of values
    Minimum:247.28
    Maximum:247.80
    Units:meters
    Additional Testing
    Added_Tests: The data presented here contain all of the vertical effective stress steps and corresponding void ratios. At certain steps, additional test procedures were done. Results from these additional tests are reported in the other elements of this data release. The additional tests include shear strength (Direct Shear Test, utilizing the DSC), and permeability (Permeability Test, utilizing the ESC). The vertical effective stress step at which each subsection was depressurized to dissociate any gas hydrate present is also indicated (Dissociation). A blank indicates no additional tests were performed at that effective stress step. (Source: U.S. Geological Survey) Character set (text).
    Vertical Effective Stress (Megapascal)
    Vert_Eff_Stress_MPa: This is the 1-dimensional (vertical) stress applied to the specimen during the consolidation test. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.129
    Maximum:9.241
    Units:megapascals
    Void Ratio (unitless)
    Void_Ratio: Void ratio is the volume of void space (filled with deionized water in tests with data in this column) divided by the volume of solid sediment in the specimen. This parameter has no units. As the applied vertical stress increases, the specimen tends to become shorter and the volume of void space decreases. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.533
    Maximum:1.484
    Units:None
    Compressional Wave Velocity (Vp in meters per second)
    Vp_mps: Compressional wave velocity, measured along the axial direction of the core (vertical direction in situ). A blank indicates no measurement was made at that stress state. Note that only the DSC has the wave-velocity measurement capacity. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1634
    Maximum:2113
    Units:meters per second
    Constrained Modulus from Vp (Megapascal)
    M_Vp_Mpa: Constrained modulus for small strains, calculated from the wave velocity measurements. A blank indicates no measurement was made at that stress state. Note that only the DSC has the wave-velocity measurement capacity required for calculating M_Vp. (Source: U.S. Geological Survey)
    Range of values
    Minimum:2949
    Maximum:9257
    Units:megapascal
    Constrained Modulus from Consolidation (Megapascal)
    M_Consol_Mpa: Constrained modulus for large strains, calculated from the consolidation measurements. A blank indicates no measurement was made at that stress state. (Source: U.S. Geological Survey)
    Range of values
    Minimum:11.4
    Maximum:95.6
    Units:megapascal
    Entity_and_Attribute_Overview:
    These data are available in a Microsoft Excel XLSX as well as a CSV format. The first two rows in the XLSX file are header rows, where the second row is an abbreviated column label intended for software packages that are unable to cope with longer labels available in the first row of the XLSX file. The first part of the attribute definition (before the colon) indicates the abbreviated column label. The first row of the CSV file is a header line and is the same as the abbreviated column label on the second row of the XLSX file.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Junbong Jang
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov

Why was the data set created?

The purpose of this dataset is to report several different measures of the stiffness of the fine-grained seal sediment collected in pressure core NGHP-02-08-30P. Stiffness information is given in terms of the stress-strain curves measured during consolidation, with the compressional wave velocity (Vp) and with the constrained modulus. In this work, the constrained modulus (M) is calculated from the consolidation data, and from the wave velocity (Mvp).

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: 03-Jul-2015 (process 1 of 8)
    Deployment sample collection: This study used sediment from pressure core NGHP-02-08-30P, collected from Site NGHP-02-08 in Area C of the Bay of Bengal offshore Eastern India. Pressure core collection requires the rotary corer to retract the core through a ball valve and into an autoclave at the in situ coring depth. Once retracted into the autoclave, the ball valve at the base of the autoclave can be closed, sealing the core within the autoclave. A connected high-pressure nitrogen canister provides pressure stabilization as the autoclave is brought through different thermal regimes on the trip to the rig floor. Once the autoclave is recovered, it is chilled in an ice bath to stabilize the core contents, then transferred to a temperature-controlled unit for core manipulation. During NGHP-02, depth below sea floor was based on the continuous downhole log of the drill pipe length. The sea floor depth reference (mudline) was determined from a combination of noting when the drill string contacted the sea floor and increased the measured weight-on-bit, and visual verification of the drill bit position using an ROV. Here, depth is reported using the IODP standard depth terminology CSF-B (total depth from sea floor to target sediment, after all gas expansion gaps have been removed). Person who carried out this activity:
    U.S. Geological Survey
    Attn: William F. Waite
    Research Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2346 (voice)
    wwaite@usgs.gov
    Date: 2015 (process 2 of 8)
    Core preparation and transport: Note that throughout the core preparation, transport and testing stages, the hydrostatic pressure is maintained at or above in situ values to maintain the stability of the core contents and avoid the formation of gas bubbles. Once the core-filled autoclave was brought to the rig floor and its temperature was stabilized, the autoclave was transferred to a shipboard analysis laboratory. In the laboratory, a pressurized system extracted the core from the autoclave, cut the core to a prescribed length (1.2 meters for the NGHP-02-08-30P core described here), and inserted the 1.2 m-long section into a pressurized storage chamber. The storage chamber can then be isolated via a ball valve closure and, ultimately, shipped in a Department of Transportation-approved, refrigerated overpack system to the U.S. Geological Survey’s Woods Hole Coastal and Marine Science Center for analysis (WHCMSC). Person who carried out this activity:
    U.S. Geological Survey
    Attn: William F. Waite
    Research Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2346 (voice)
    wwaite@usgs.gov
    Date: 2017 (process 3 of 8)
    Pressure Core Characterization Tool (PCCT) Core Manipulation: Once the core storage chamber arrived at WHCMSC, it was moved into a refrigerated core storage facility to maintain the core’s temperature stability. The core was subsequently tested in the WHCMSC High Pressure Core Analysis Laboratory (HyPrCAL) using the PCCTs (see the browse graphic for this data releases primary landing page). Similar to the shipboard setup, the core was first retrieved, at pressure, from the storage chamber, then individual specimens were cut and inserted into either the Direct Shear Chamber (DSC) or Effective Stress Chamber (ESC). The core manipulation and transfer into the testing chambers was accomplished at a hydrostatic pressure between 10-11 MPa (Megapascal). Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2017 (process 4 of 8)
    Testing Chamber Overview: Once a test specimen is isolated in one of the testing chambers, the sediment is extruded from the plastic core liner using a plunger that will eventually serve as the specimen’s top endcap once the specimen is pushed all the way out of the liner and into the primary testing space. The plunger is then used to apply a vertical effective stress, returning the specimen to its in situ state of effective stress (approximately 2 MPa). Additional vertical effective stress can be applied to test the specimen response to the increasing effective stress that will occur in situ when the formation is depressurized to extract methane from gas hydrate. In this study, vertical effective stress is increased in steps, with each step held long enough for the specimen to consolidate. The consolidation (specimen shortening) is monitored via a linear voltage displacement transducer (LVDT) and reported here in terms of the void ratio. The void ratio is calculated according to the derivation in ASTM D2435 [ASTM, 2011]. Void ratio is unitless, and is reported here with an accuracy of 0.0005. Vertical stress is measured via a load cell, and reported here with an accuracy of 5 kPa (kilopascal). Once the specimen is consolidated to the peak effective vertical stress and all high-stress testing is complete, the vertical effective stress is released (again, in steps). Once the specimen is back at its in situ effective stress state, the specimen is depressurized by reducing both the pore pressure and vertical effective stress together to retain the in situ vertical effective stress. If there is any gas hydrate in the specimen, this step breaks that gas hydrate down, releasing the methane and water. Additional consolidation testing is done after depressurization.
    ASTM D2435 / D2435M-11, Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading, ASTM International, West Conshohocken, PA, 2011, www.astm.org , DOI: 10.1520/D2435_D2435M-11. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2017 (process 5 of 8)
    Direct Shear Chamber (DSC): The DSC and its operations are described in Santamarina and others (2012, 2015). Briefly, the DSC applies a vertical stress to a core specimen held in a three-layer specimen chamber bounded at either end by endcaps containing compressional wave velocity transducers. The middle layer can be horizontally moved, shearing the specimen along the top and bottom of the middle layer. In this data release, the following parameters are reported as functions of the applied effective vertical stress: void ratio, compressional wave velocity, and constrained modulus. The derivations of compressional wave velocity and constrained modulus are given as follows:
    Compressional Wave Velocity, Vp: Throughout the consolidation process, compressional waveforms are collected in the axial direction, with results reported here in terms of wave velocity (waveform travel time divided by specimen length). The uncertainty in Vp is 1.5 percent.
    Constrain Modulus, M: The constrained modulus is calculated two different ways, representing the specimen stiffness for deformation at two different length scales. The first method recovers the small-strain constrained modulus, Mvp (stiffness for microscopic strains induced by the compressional wave transducers). The formula is Mvp = (specimen density)x((Vp)^2).
    The second method recovers the constrained modulus for consolidation, Mconsol (macroscopic deformation) via the formula Mconsol = -(1+ei)x(change in vertical effective stress)/(change in e), where e is the void ratio, and ei is the void ratio at the beginning of the effective vertical stress step increase. The specimen is much stiffer for microscopic deformations than macroscopic deformations, so Mvp is larger than Mconsol. The uncertainty in both constrained moduli is 3 percent.
    Santamarina, J.C., Dai, S., Jang, J., and Terzariol, M., 2012, Pressure core characterization tools for hydrate-bearing sediments: Scientific Drilling, v. 14, p. 44-48.
    Santamarina, J.C., Dai, S., Terzariol, M., Jang, J., Waite, W.F., Winters, W.J., Nagao, J., Yoneda, J., Konno, Y., Fujii, T., and Suzuki, K., 2015, Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough: Marine and Petroleum Geology, v. 66, p. 434-450. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2017 (process 6 of 8)
    Effective Stress Chamber (ESC): In the primary testing chamber of the ESC, a thin latex sleeve can be pressed against the cylindrical sides of the specimen, and the upper and lower specimen endcaps have porous stones connected to fluid flow lines that enable flow-through vertical permeability measurements to be made in the ESC. The ESC and its operations are described in Santamarina and others (2012, 2015). A sample permeability measurement is provided in the permeability section of this data release, accessible from the primary landing page. In this portion of the data release, only the consolidation data and associate constrained modulus, Mconsol, are reported, again with an uncertainty of 3 percent. The consolidation procedure follows that of the DSC given above.
    Santamarina, J.C., Dai, S., Jang, J., and Terzariol, M., 2012, Pressure core characterization tools for hydrate-bearing sediments: Scientific Drilling, v. 14, p. 44-48.
    Santamarina, J.C., Dai, S., Terzariol, M., Jang, J., Waite, W.F., Winters, W.J., Nagao, J., Yoneda, J., Konno, Y., Fujii, T., and Suzuki, K., 2015, Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough: Marine and Petroleum Geology, v. 66, p. 434-450. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2017 (process 7 of 8)
    Data archiving: Microsoft Excel version 15.33 was used to consolidate all data in a spreadsheet. Measured interface heights and elapsed times were arranged by sediment and pore fluid type. Results were then exported to a comma-separated values (csv) file format. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 06-Aug-2020 (process 8 of 8)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?

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

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Horizontal position was determined by GPS satellite data, which provided guidance information for the dynamic positioning system (DPS) utilized by the D/V Chikyu. The DPS also utilizes inputs from tidal, wind and wave data to control six azimuthal thrusters beneath the ship’s hull. The thrusters are capable of 360 degree adjustment. Given the DPS capabilities, borehole locations for the D/V Chikyu are considered to be accurate to a radius of 15 meters. Details are provided in: Chikyu Hakken – Earth Discovery, Volume 1, Spring 2005, published by JAMSTEC’s Center for Deep Earth Exploration: https://www.jamstec.go.jp/chikyu/e/magazine/backnum/pdf/hk_01_e.pdf
  3. How accurate are the heights or depths?
    Coring depth measurements used on the D/V Chikyu during NGHP-02 followed standard International Ocean Drilling Program (IODP) protocols. Assessment of these protocols by IODP had determined the vertical position accuracy is on the order of centimeters to meters. Additional information about the depth conventions and accuracy are on pages 8 and 9 of the IODP report “IODP Depth Scales Terminology”: http://www.iodp.org/policies-and-guidelines/142-iodp-depth-scales-terminology-april-2011/file. Depth resolution ranges from 0.01 to 1 meter.
  4. Where are the gaps in the data? What is missing?
    Both chambers yield the void ratio dependence on vertical effective stress, but not all measurements are possible in the two chambers used in this study. The Direct Shear Chamber (DSC) can be used for compressional wave velocity measurements (Vp) and thus for calculating the constrained moduli from Vp as well as from the void ratio dependence on vertical effective stress. The DSC is also used to obtain direct shear strength measurements (See the NGHP02_AreaC_Direct_Shear_Data dataset in this data release). The Effective Stress Chamber (ESC) only provides the constrained modulus via the consolidation data, but the ESC can also measure permeability (See the NGHP02_AreaC_Permeability_Data dataset in this data release). Blank entries within a column of measured data occur because that measurement is not possible for the given vertical effective stress or in the given measurement chamber.
  5. How consistent are the relationships among the observations, including topology?
    Specimen collection via pressure core, and maintenance of high pore pressures throughout the specimen collection and testing process, is required because these are gassy sediment that potentially contain gas hydrate. Allowing these specimens to depressurize prior to testing would allow gas bubbles to form, expand, and disrupt the sediment fabric that determines the in situ moduli, permeability and strength reported in this data release.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None.
Use_Constraints:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? This dataset contains four files: NGHP02_AreaC_Stress_Strain_Modulus_Data.xlsx (data in an Excel spreadsheet), NGHP02_AreaC_Stress_Strain_Modulus_Data.csv (same data in a comma-separated text file), NGHP02_AreaC_Stress_Strain_Modulus_BrowseGraphic.png (browse graphic), and FGDC CSDGM metadata in XML format.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data are available in XLSX and CSV formats, and a browse graphic in PNG format. The user must have software capable of reading the data formats.

Who wrote the metadata?

Dates:
Last modified: 06-Aug-2020
Metadata author:
U.S. Geological Survey
Attn: William F. Waite
Geophysicist
384 Woods Hole Rd.
Woods Hole, MA

508-548-8700 x2346 (voice)
508-457-2310 (FAX)
wwaite@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P91XJ7DP/NGHP02_AreaC_Stress_Strain_Modulus_Metadata.faq.html>
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