Methods and apparatus for measurement of electronic properties of geological formations through borehole casing

Patent · Tue Aug 27 04:00:00 EDT 1991

OSTI ID:7178970

Vail, III, W B

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 the 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 are present. Lithological characteristics of the formation such as the presence 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. 48 figures.

• DOE Contract Number: FG06-84ER13294
• Assignee: ParaMagnetic Logging Inc., Woodinville, WA (United States)
• Patent Number(s): A; US 5043668
• Application Number: PPN: US 7-435273
• OSTI ID: 7178970
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
440400 -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
DESIGN
DIELECTRIC PROPERTIES
ELECTRIC CONDUCTIVITY
ELECTRIC LOGGING
ELECTRICAL PROPERTIES
EQUIPMENT
GEOLOGY
LITHOLOGY
MWD SYSTEMS
NATURAL GAS WELLS
OIL WELLS
OPERATION
PETROLOGY
PHYSICAL PROPERTIES
POLARIZATION
RESERVOIR ROCK
RESISTIVITY LOGGING
WELL CASINGS
WELL LOGGING
WELL LOGGING EQUIPMENT
WELLS