Methods of operation of apparatus measuring formation resistivity from within a cased well having one measurement and two compensation steps
A method is described of determining the resistivity of geological formations from within a cased well that provides three independent measurements including a current leakage measurement quantity, first order error information, and second order error information to provide an accurate determination of the resistivity of a geological formation adjacent to a cased well, comprising: providing three spaced electrode means that electrically engage a particular section of casing with a first resistance being defined between first and second electrode means and a second resistance being defined between second and third electrode means; providing current conducting means and current generating means causing a first current to flow into the geological formation from the particular section of casing and causing a second current to flow along the particular section of casing; obtaining a current leakage measurement quantity relating to first current flow into the formation and the magnitudes of the first and second resistances; obtaining first order error information related to second current flow along the casing and any differences between the first and second resistances; obtaining second order error information related to any first current flow into formation and any differences between the first and second resistances; and determining a magnitude relating to the resistivity of the geological formation by compensating said current leakage measurement quantity with said first order error information and with said second order error information to provide information useful for the accurate determination of the resistivity of the geological formation adjacent to cased the cased well.
- Assignee:
- Para Magnetic Logging, Inc., Woodinville, WA (United States)
- Patent Number(s):
- US 5223794; A
- Application Number:
- PPN: US 7-754965
- OSTI ID:
- 6440058
- Resource Relation:
- Patent File Date: 4 Sep 1991
- Country of Publication:
- United States
- Language:
- English
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