Accuracy of borehole gravity data

Journal Article · Sat Apr 01 04:00:00 EST 1978 · Geophysics; (United States)

DOI:https://doi.org/10.1190/1.1440834· OSTI ID:5337513

Schmoker, J W

Repeated subsurface gravity measurements, obtained with the U.S. Geological Survey-LaCoste and Romberg borehole gravity meter, were studied to determine the accuracy of the borehole gravity data, the dependence of accuracy upon elapsed time and vertical separation, and the precision of bulk densities calculated from borehole gravity measurements. The likelihood of poor interval gravity measurements increases sharply for vertical intervals greater than 150 ft, and increases approximately linearly with increasing time between readings. After a brief warmup period, data quality does not improve with the passage of time from the beginning of the survey. If the stations of a borehole gravity survey are separated by less than 70 ft, and the time between readings is less than 18 minutes, the gravity difference between two points in a borehole can be measured to +-10 sigma gals. For intervals greater than 20 ft, this is equivalent to a density error of +-.02 g/cm/sup 3/ or less.

• Research Organization: Geological Survey, Denver, CO
• OSTI ID: 5337513
• Journal Information: Geophysics; (United States), Journal Name: Geophysics; (United States) Vol. 43:3; ISSN GPYSA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580203* -- Geophysics-- Geophysical Survey Methods-- (1980-1989)
ACCURACY
BOREHOLES
BULK DENSITY
CAVITIES
DENSITY
GRAVITY LOGGING
PHYSICAL PROPERTIES
TIME DEPENDENCE
WELL LOGGING