Apparatus for focused electrode induced polarization logging
An induced polarization logging tool is described for measuring parameters of a formation surrounding a borehole. The logging tool consists of: a non-conductive logging sonde; a plurality of electrodes disposed on the sonde, the electrodes including at least a survey current electrode and guard electrodes disposed on opposite sides of the survey current electrode, a non-polarizing voltage measuring electrode, a non-polarizing voltage reference electrode and a current return electrode, both the voltage reference and current return electrodes being located a greater distance from the survey current electrode than the guard electrodes; means connected to the survey current electrode and the guard electrodes for generating a signal representative of the potential difference in the formation between the survey current electrode and the guard electrodes; first control means directly coupled to the survey current electrode, the first control means controlling the current flow to the survey current electrode in response to the potential difference signal; a second control means directly coupled to the guard electrodes to control the current flow to the guard electrodes in response to the potential difference signal; a source of alternating current located at the surface, one end of the source being coupled to the two control means and the other to the current return electrode, the source supplying alternating current at various discrete frequencies between substantially 0.01 and 100 Hz; measurement means directly coupled to the voltage measurement and survey current electrodes to measure the amplitude and phase of the voltage induced in the formation and the amplitude and phase of the current flow to the survey electrode; and transmission means for transmitting the measurements to the surface.
- Assignee:
- Shell Oil Co., Houston, TX
- Patent Number(s):
- US 4583046
- OSTI ID:
- 5669520
- Resource Relation:
- Patent File Date: Filed date 20 Jun 1983
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
47 OTHER INSTRUMENTATION
PETROLEUM DEPOSITS
INDUCED POLARIZATION LOGGING
ALTERNATING CURRENT
AMPLITUDES
BOREHOLES
DATA TRANSMISSION
ELECTRIC POTENTIAL
ELECTRODES
HZ RANGE
SIGNALS
VOLTMETERS
CAVITIES
COMMUNICATIONS
CURRENTS
ELECTRIC CURRENTS
ELECTRIC LOGGING
ELECTRIC MEASURING INSTRUMENTS
ELECTRICAL EQUIPMENT
EQUIPMENT
FREQUENCY RANGE
GEOLOGIC DEPOSITS
MEASURING INSTRUMENTS
MINERAL RESOURCES
RESOURCES
WELL LOGGING
020200* - Petroleum- Reserves
Geology
& Exploration
440400 - Well Logging Instrumentation