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Application of borehole geophysical methods to shallow groundwater investigations
Date
1987Type
DissertationDepartment
Geological Sciences and Engineering
Degree Level
Doctorate Degree
Degree Name
Hydrogeology/Hydrology
Abstract
Borehole geophysical methods have been used extensively for petroleum and mineral exploration; but due to differences in environment and survey objective, modifications of both equipment and interpretation are necessary for shallow groundwater applications. These applications require the use of complementary borehole measurements which can be related to the formation properties by comparison to core samples. Different interpretation strategies must be developed for different environments, strategies for use in unsaturated, saturated with clay present, saturated without clay present, and hydraulically anisotropic environments are developed. Parameters that can be determined are porosity, moisture content, hydraulic conductivity, groundwater velocity, cation exchange content, and pore fluid conductivity. All logging instrumentation measures a property over a short interval of the well. It is important when combining logs to insure that all logs used in the comparison are vertical averages of the same portion with respect to both depth and length of the well. It is also possible to reduce the effect of the vertical averaging by the instrumentation through the use of numerical techniques. A field example is used to demonstrate these methods. The techniques presented make it practical to determine a formation hydraulic properties on a scale of a few tens of centimeters. This high resolution distribution of the formation in turn permits the development of a class of contaminate transport models which utilize the high resolution description of the aquifer variability. These models do not require large scale dependent dispersity terms to match field data because the contaminate movement is realistically described by shear flow in the high resolution advective flow field of the model. A one dimensional model is presented as an example of this class of model.
Description
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Permanent link
http://hdl.handle.net/11714/1743Subject
borehole geophysical methodspetroleum exploration
mineral exploration
environment
survey objective
modifications of equipment
modifications of interpretation
shallow groundwater applications
complimentary borehole measurements
formation properties
core
clay
samples
interpretation strategies
unsaturated with clay present
saturated with clay present
saturated without clay present
hydraulically anisotropic environments
porosity
moisture content
hydraulic conductivity
groundwater velocity
cation exchange content
pore fluid conductivity
logging instrumentation measures
wells
logs
vertical averages
depth of wells
length of wells
numerical techniques
formation hydraulic properties
high resolution distribution
contaminate transport models
high resolution description
aquifer variability
dependent diversity
contaminate movement
shear flow
high resolution advective flow field
Mackay Science Project
Additional Information
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