Method and apparatus for measuring resistivity of an earth formation
An apparatus is described for correcting anomaly induced errors in resistivity measurements of an earth formation traversed by a borehole. The resistivity measurement is accomplished utilizing voltage measurements between a sonde suspended in the borehole from a conductive cable and a first reference electrode disposed above the sonde. The apparatus comprises: means for emitting a first focusing current from the sonde at a selected frequency; a second reference electrode disposed between the first reference electrode and the sonde; means for measuring a first voltage induced by the first focusing current between the anode and the second reference electrode; means for emitting a second focusing current from the sonde at a frequency substantially below the selected frequency; means for measuring a second voltage induced by the second focusing current between the second reference electrode and the first reference electrode; means for combining the first voltage and the second voltage wherein the resultant voltage is a corrected measurement of the voltage measurement between the sonde and the first reference electrode; and means for combining the resultant voltage with the resistivity measurement to correct the resistivity measurement.
- Assignee:
- Gearhart Industries, Inc., Fort Worth, TX
- Patent Number(s):
- US 4646026
- OSTI ID:
- 6741387
- Resource Relation:
- Patent File Date: Filed date 10 Oct 1985
- Country of Publication:
- United States
- Language:
- English
Similar Records
Logging method and apparatus for measuring earth formation resistivity as well as arm mechanism for the same
Apparatus for focused electrode induced polarization logging
Related Subjects
03 NATURAL GAS
NATURAL GAS DEPOSITS
RESISTIVITY LOGGING
PETROLEUM DEPOSITS
WELL LOGGING EQUIPMENT
BOREHOLES
ELECTRIC CABLES
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
ELECTRODES
ERRORS
CABLES
CAVITIES
CONDUCTOR DEVICES
CURRENTS
ELECTRIC LOGGING
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
EQUIPMENT
GEOLOGIC DEPOSITS
MINERAL RESOURCES
PHYSICAL PROPERTIES
RESOURCES
WELL LOGGING
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration