Dynamic range control of electrode pad current in well logging tools
In apparatus for investigating earth formations traversed by a borehole, improved methods and apparatus are provided for achieving dynamic range control of formation measurements. In one embodiment adapted to formation resistivity measurements, a well logging tool moving through a borehole emits a current into the adjacent earth formation, and a corresponding measurement voltage correlative to the resistivity is sampled at discrete elevations as the tool traverses the borehole. An average of these voltage measurements is formed. When the magnitude of this average exceeds or drops below a predetermined range, the magnitude of the survey voltage is decreased or increased respectively by a discrete amount.
- Assignee:
- Dresser Industries Inc.
- Patent Number(s):
- US 4514809
- OSTI ID:
- 5269818
- Resource Relation:
- Patent File Date: Filed date 30 Apr 1982; Other Information: PAT-APPL-373776
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RESISTIVITY LOGGING
WELL LOGGING EQUIPMENT
DESIGN
CONTROL
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
ELECTRODES
VOLTMETERS
CURRENTS
ELECTRIC LOGGING
ELECTRIC MEASURING INSTRUMENTS
ELECTRICAL EQUIPMENT
EQUIPMENT
MEASURING INSTRUMENTS
WELL LOGGING
440400* - Well Logging Instrumentation