PROGRAMS AND PLANS-Establishment of a National Policy to Archive Borehole-Geophysical Logs
In Replay Refer To: September 27, 2000
Mail Stop 411
OFFICE OF GROUND WATER TECHNICAL MEMORANDUM 00.03
Subject: PROGRAMS AND PLANS-Establishment of a National Policy to Archive
Borehole-Geophysical Logs
Borehole-geophysical logging is an important part of many geologic and
hydrologic investigations. Increasingly, geophysical logs are collected as
digital data rather than paper analog charts. At present, the U.S.
Geological Survey (USGS) has no standardized format for storing digital
geophysical logs. Establishment of a standard format for storing digital
logs is important for the future development and application of USGS
geophysical databases. This memorandum presents such standards and
establishes the policy that all digital geophysical logs collected after
October 30, 2000 be archived in a District database following these
standards. The standard format has been designed to include the necessary
information, to correspond to but not duplicate what is stored in the
National Water Information System (NWIS), and to be flexible so as to not
greatly increase manual data entry.
The borehole-geophysical log archive must be in ASCII format and consist
of the following:
1. Header that includes the NWIS site ID, station name, and other ID;
logging operation and procedures; log-measuring point; magnetic
declination; borehole and hydrologic conditions at the time of logging;
and probe and calibration/standardization information (probe type and
serial number and calibration/standardization date, standard, and
response).
2. Data-identification heading that immediately precedes the data records
and describes the data by column and includes a depth column heading
followed by log parameter column heading(s); the column headings consist
of two lines, parameter names on the top and corresponding units below.
3. Data records that include depth values and corresponding data values for
one or more log parameters.
ASCII headings and data records generated following the Log ASCII
Standard (http://www.cwls.org/las_info.htm) and other common digital
logging formats are acceptable for archiving purposes. An example log
archive entry is shown in Attachment A.
An NWIS site must be established for the logged borehole. Borehole
construction greatly affects geophysical log response. Many boreholes are
logged prior to their final completion so timing and details of
construction in relation to log-data collection is critical for log
analysis. The casing and opening type, depth, and diameter data for the
hole at the time of logging must be part of the construction data sequence
entries in NWIS. Information on logging operation and procedures,
log-measuring point, magnetic declination for magnetically oriented logs,
borehole and hydrologic conditions, and probe calibration/standardization
also is critical for log analysis but presently is not stored in NWIS.
This information, therefore, must be stored as part of the log header.
As shown in the example (Attachment A), any pre-existing log headers
should be included after the standard header and before the headings and
data records. In most cases, digital logs can be easily entered into the
data archive by simply adding the standard header in front of the log-data
file. A log header entry program has been developed to aid in the
generation of the standard header.
Some digital log data such as acoustic- and optical-televiewer and
borehole-radar data are not conducive for conversion to a standard format,
so they will need to be archived in their existing form. Software needed
to display and analyze such log data should be identified in the log
header.
Each District will set up an archive on a locally based computer system.
The archive will consist of a main directory called LOGARCHIVE. Each
geophysical log file name will include the NWIS 15-digit Site ID number,
date of log collection (year month day), two-letter log-type code, and
sequence number extension. The first log of the same type collected on a
particular day would have a sequence number of 01, the second, 02, etc.
The path name for the example entry shown in Attachment A would be:
LOGARCHIVE>424531077564201.20000601.MI01
An executable file of any software needed for analysis of non-standard
log files should be included in the LOGARCHIVE with explanation of security
measures for proprietary programs.
The log header entry program may be downloaded from the Office of Ground
Water (OGW) internal web page (/usgs/ogw). The master
lists of geophysical log-type codes and heading-log parameters and units
also will be maintained on the OGW web page. Requests for additional log
types and parameters should be directed to the OGW Borehole Geophysics
Advisor (jhwillia@usgs.gov). The Regional Ground-Water Specialists are to
act on behalf of the Office of Ground Water to assure that the
borehole-geophysical logs collected by the Districts are properly archived.
Adherence to the policy of archiving borehole-geophysical logs will
ensure that data collected by District offices will remain available for
support of published reports, future scientific investigations, and data
requests from the public.
William M. Alley
Chief, Office of Ground Water
Attachment
Distribution: A (without attachment)
DC, Regional Ground-Water Specialists, NR, SR, CR, WR
Chief, Branch of Geophysical Applications and Support, CT
John Williams, NY
Attachment A Example log archive
U.S. GEOLOGICAL SURVEY
GEOPHYSICAL LOG
(output from log header entry program)
Site ID (C1): 424531077564201
Station name (C12): 515
Other ID (C190): MW-8
Date of log: 06-01-00
Start time of log: 15:35
Office/logging unit: USGS Any District
Logging operator: Jane Smith
Observer: John Doe
Description of log-measuring point: Land Surface
Height of log-measuring point above/below land-surface datum: 0.0 FT
Altitude of log-measuring point (NGVD): 516.0 FT
Log orientation: Magnetic North
Magnetic declination: 10
Logging direction: UP
Logging speed: 20 FT/MIN
Depth error after logging: 0.8 FT
Logging probe manufacturer: Century
Logging probe model: EM Induction, Gamma #9510
Logging probe serial number: 746
Description of calibration/standardization: Century Calibration Ring
Date of calibration/standardization: 06-01-2000
Standard: 0 ms/M
Response: 72775 CPS
Standard: 690 ms/M
Response: 110400 CPS
Borehole fluid type: WATER
Depth of borehole fluid below log-measuring point: 364 FT
Borehole fluid resistivity/conductivity: 8 OHM-M
Borehole fluid temperature: 53.5 F
Hydrologic conditions: Mine-room roof collapse resulted in flooding of the
mine and major drawdown
in the overlying aquifers.
Software for non-ASCII logs: NA
Remarks: Borehole is 200 ft southwest of the edge of the sinkhole formed by
the mine-roof collapse.
Attachment A (cont.)
(pre-existing log header--from logging software)
COMPANY : US GEOLOGICAL SURVEY
WELL : MW-8
LOCATION/FIELD : SALTVILLE
COUNTY : SALT
STATE : ANY
SECTION : TOWNSHIP : RANGE :
DATE : 06/01/00 ELEV. PERM. DATUM :
DEPTH DRILLER : 702 LOG MEASURED FROM: LSD GL
LOG BOTTOM : 701.9 DRL MEASURED FROM:
LOG TOP : 516.7 LOGGING UNIT : ANY TYPE : 9510C
CASING DRILLER : 520 FIELD OFFICE : ANY THRESH:
CASING TYPE : STEEL RECORDED BY : JANE SMITH
CASING THICKNESS : BOREHOLE FLUID : WATER
BIT SIZE : 6
DEPTH GAM(NAT) COND RES(FL) | data
identification heading
FT CPS MMHO/M OHM-M |
516.7 21 5552.334 0.180 |
516.8 40 5543.827 0.180 |
................. |
ASCII data
................. |
701.8 210 27.428 36.459 |
701.9 245 28.732 34.804 |