Calibration of density logs at the Nevada Test Site

PDF Version Also Available for Download.

Description

During the evaluation of a proposed site for an underground nuclear test at the Department of Energy`s Nevada Test Site (NTS) it was important to measure the bulk density of the geological formation in which the test was to be executed. The most satisfactory method for this measurement is the density log. This is a measurement system in which a gamma-ray source and detector are mounted in an instrument (a sonde) which is lowered into a borehole by a multi-conductor cable, and the number of gamma rays detected is used to infer the bulk density. At NTS many of the ... continued below

Physical Description

21 p.

Creation Information

Hearst, J.R. April 1, 1995.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Author

Sponsor

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

During the evaluation of a proposed site for an underground nuclear test at the Department of Energy`s Nevada Test Site (NTS) it was important to measure the bulk density of the geological formation in which the test was to be executed. The most satisfactory method for this measurement is the density log. This is a measurement system in which a gamma-ray source and detector are mounted in an instrument (a sonde) which is lowered into a borehole by a multi-conductor cable, and the number of gamma rays detected is used to infer the bulk density. At NTS many of the boreholes of interest are air-filled, with diameters as large as 3.65 m, drilled in partially-saturated media. Consequently the commercial equipment and calibration procedures are not suitable for NTS conditions. The count rate from a density sonde is strongly affected by any gap between the sonde and the borehole wall, especially if the gap is filled with air rather than water. Modern commercial density logs employ two detectors, and use one of the detectors to compensate for borehole conditions such as mudcake and gap. The commercial compensation algorithms assume that the sonde is parallel to the borehole wall; a reasonable assumption for oilfield conditions but not for NTS conditions. Moreover, in an air-filled borehole, borehole diameter affects both the calibration and the compensation. Therefore we could not use commercial algorithms to deal with NTS conditions. For many years, no appropriate two-detector algorithm was available for the NTS situation. Consequently we developed special algorithms for a single-detector sonde, which was equipped to measure the gap directly. Recently a two-detector algorithm was developed, which appears to be satisfactory if the sonde is calibrated in the appropriate-diameter borehole. In this report we describe the calibration procedures and the algorithms for both methods.

Physical Description

21 p.

Notes

OSTI as DE95012481

Source

  • Other Information: PBD: Apr 1995

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Other: DE95012481
  • Report No.: UCRL-ID--120664
  • Grant Number: W-7405-ENG-48
  • DOI: 10.2172/79042 | External Link
  • Office of Scientific & Technical Information Report Number: 79042
  • Archival Resource Key: ark:/67531/metadc723805

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • April 1, 1995

Added to The UNT Digital Library

  • Sept. 29, 2015, 5:31 a.m.

Description Last Updated

  • Feb. 16, 2016, 2:36 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 2

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Hearst, J.R. Calibration of density logs at the Nevada Test Site, report, April 1, 1995; California. (digital.library.unt.edu/ark:/67531/metadc723805/: accessed November 24, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.