Methods and apparatus for measurement of electronic properties of geological formations through borehole casing
- (Bothell, WA)
Methods and apparatus are provided for measuring electronic properties of geological formations and cement layers adjacent to cased boreholes including resistivities, polarization phenomena and dielectric constants. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. At least three voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of the differential current conducted into formation in the vicinity of those electrodes. These measurements facilitate calculation of the resistivities of the adjacent geological formations as well as an indication of whether cement is present. Measurements of the differential voltage response to transient currents provide a measurement of the polarization phenomena in formation as well as the capacitance of the casing in contact with the formation which is useful for determining whether oil and gas present. Lithological characteristics of the formation such as the pressence or absence of clay can also be determined. A calibration procedure is provided for minimizing errors induced by variations in the casing. The device also may be placed within the pipe attached to a drill bit while drilling open holes.
- Research Organization:
- ParaMagnetic Logging, Inc. (Bothell, WA)
- DOE Contract Number:
- FG06-84ER13294
- Assignee:
- ParaMagnetic Logging Inc. (Woodinville, WA)
- Patent Number(s):
- US 5043668
- OSTI ID:
- 867955
- Country of Publication:
- United States
- Language:
- English
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Methods and apparatus for measurement of electronic properties of geological formations through borehole casing
Methods and apparatus for measurement of electronic properties of geological formations through borehole casing
Related Subjects
apparatus
measurement
electronic
properties
geological
formations
borehole
casing
provided
measuring
cement
layers
adjacent
cased
boreholes
including
resistivities
polarization
phenomena
dielectric
constants
current
passed
electrode
electrical
contact
interior
surface
earth
voltage
electrodes
measure
various
thereon
differences
discrete
pairs
provide
differential
conducted
formation
vicinity
measurements
facilitate
calculation
indication
response
transient
currents
capacitance
useful
determining
oil
gas
lithological
characteristics
pressence
absence
clay
determined
calibration
procedure
minimizing
errors
induced
variations
device
placed
pipe
attached
drill
bit
drilling
holes
measuring electrodes
dielectric constants
geological formations
dielectric constant
electrical contact
drill bit
voltage measuring
cased boreholes
electronic properties
borehole casing
adjacent geological
geological formation
voltage difference
transient current
calibration procedure
pipe attached
cased borehole
casing measure
cement layers
differential current
voltage differences
electrodes provide
current conducted
polarization phenomena
measuring electronic
measuring electrode
errors induced
layers adjacent
discrete pairs
cased bore
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